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Electromagnetic Field, Health and

Environment

Proceedings of EHE’07

Edited by

Andrzej Krawczyk

Central Institute for Labour Protection, Department of Bioelectromagnetics,

Warsaw, Poland

Roman Kubacki

Military University of Technology, Warsaw, Poland

Sławomir Wiak

Technical University of Lodz, Institute of Mechatronics and

Information Systems, Lodz, Poland

and

Carlos Lemos Antunes

University of Coimbra, Electrical Engineering Department,

Coimbra, Portugal

Amsterdam • Berlin • Oxford • Tokyo • Washington, DC

© 2008 The authors and IOS Press.

All rights reserved. No part of this book may be reproduced, stored in a retrieval system,

or transmitted, in any form or by any means, without prior written permission from the publisher.

ISBN 978-1-58603-860-1

Library of Congress Control Number: 2008926255

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PRINTED IN THE NETHERLANDS

Electromagnetic Field, Health and Environment v

A. Krawczyk et al. (Eds.)

IOS Press, 2008

© 2008 The authors and IOS Press. All rights reserved.

Introductory Remarks

The book mirrors the image of the EHE’07 conference (2nd International Conference

on Electromagnetic Fields, Health and Environment) which was held in Wroclaw, Po-

land, 10–12 September 2007. The conference, the second in chain of EHE confer-

ences – the first one, EHE’06, was held on April 27–29, 2006 on Madeira Island, Por-

tugal – gathered engineers, biologists and physicists dealing with bioelectromagnetic

problems, i.e. it attracted people investigating the phenomenon of interaction of elec-

tromagnetic field and biological objects. The problem is of great importance as the

number of sources of electromagnetic field has increased dramatically in the last dec-

ades and still keeps growing. Both producers of electromagnetic energy and its con-

sumers want to produce and to consume more and more energy, the first group because

of commercial benefits while the second one because of their quality of life. And,

somewhere aside there are groups of ecologists, journalists, medical doctors, who sus-

pect, correctly or not, that electromagnetic field can interfere with living creatures. For

many years has the discussion about these interactions lasted, and many scientific con-

ferences have witnessed numerous emotional disputes. Because of the nature of non-

ionizing radiation, i.e. because its effect in human is reversible and hardly measured

inside, all the debates, and relevant discussions are very emotional and do not leave

much place for scientific arguments. The ambiguity around bioelectromagnetism is

especially seen in mass-media, where, almost every day, completely unfounded facts

are revealed only evoking anxiety among people.

It seems to us that such book as you have in your hands, conferences as EHE, and

many other similar scientific events, as well as series of books and scientific journals

try to enlighten the problem with the use of scientifically founded facts. Of course, the

discussion among scientists can be, and very often is, fierce and long-lasting, but all is

carried out and kept within methodological discipline, which does not allow to go no-

where.

The particular targets of the book can be briefly summarized as reviewing, present-

ing and discussing innovations in Computer Modelling, Measurement and Simulation

of Bioelectromagnetic Phenomena, analysing physical and biological aspects of Bio-

electromagnetic Phenomena, and discussing Environmental Safety and Policy issues as

well as relevant International Standards.

To make some order in reading the book, all the contributions are divided into 5

chapters which are named as follows:

1. Electromagnetic Field & Environment,

2. Electromagnetic Field & Health,

3. Electromagnetic Field & Biology,

4. Computer Simulation in Bioelectromagnetics,

5. Electromagnetic Field in Policy and Standards.

Three contributions are behind the above categorization and foreword the volume:

the first contribution shows the brief essay on Heinrich Rudolf Hertz on the occasion of

his 150 birth anniversary, the second summarizes the long-lasting research in magnetic

vi

stimulation and bioimaging and the third one considers some theoretical aspects of

electromagnetic field.

We, the Editors of the volume, as well as all the authors whose contributions are

the essence of the book, are convinced that all those who read it can find the subjects

they are interested in.

Editors:

Andrzej Krawczyk

Roman Kubacki

Sławomir Wiak

Carlos Lemos Antunes

vii

Contents

Introductory Remarks v

Andrzej Krawczyk, Roman Kubacki, Sławomir Wiak and Carlos Lemos Antunes

General Papers

Some Remarks on Life and Achievements of Heinrich Rudolph Hertz on His

150th Birth Anniversary 3

Agnieszka Byliniak and Andrzej Krawczyk

New Horizon in Biomagnetics and Bioimaging 8

Shoogo Ueno

Self-Field Theory: Analytic Spectroscopy of the Photon 18

Anthony H.J. Fleming

Chapter 1. Electromagnetic Field and Environment

Supervision of State System of Protection Against 0 Hz – 300 GHz

Electromagnetic Fields Exposure in Poland 27

Halina Aniołczyk

Electromagnetic Interaction and Ergonomic Aspect Related to Operation of

Computer Monitors 32

Karol Bednarek

Magnetic Field Around Asynchronous Electrical Machines with Variable

Frequency 38

Felipe Díaz, Fabián Déniz and Guillermo Hernández

Measurement of Electromagnetic Fields in the Vicinity of 66kV/20kV

Substation Power (Gran Canaria Island, Spain) 43

Fabián Déniz, Felipe Díaz, Antonio Pulido and Miguel Martínez

Magnetic Field Exposure from Multiple Overhead Transmission Line in Urban

Utilities Corridor 47

Mário L. Pereira Filho and José Roberto Cardoso

Determining Health Risk of 154kV, 50Hz Power Transmission Line 53

Cihan Guneser, Ozge Sahin and Hacer Sekerci Oztura

Improvement of Electromagnetic Compatibility an Electro-Energetic Network

with Converter Power Supply System and Their Influence for Environmental

Protection 58

Zygmunt Szymanski

viii

Chapter 2. Electromagnetic Field and Health

Effects of Radiation in Cellular Cultures 67

M. Filomena Botelho, A. Cristina Santos, M. Carmo Lopes, Marta Pinto,

Isabel Carreira, Inês Aleixo, Inês Rolo, Luís Neves, Ricardo Costa,

Rosemeyre Cordeiro, Cláudia Ferreira, Gilberto Almeida, Hugo Tavares,

Joana Marques, João Castro and M. João Bártolo

Influence of Static Electric Field Generated Nearby High Voltage Direct Current

Transmission Lines on Hormonal Activity of Experimental Animals 72

Grzegorz Cieslar, Paweł Sowa, Beata Kos-Kudla and Aleksander Sieron

Classifying Endogenous Rhythms in Pacemaker ECG Signals 79

Agnieszka Duraj and Andrzej Krawczyk

Neurophysiological Investigations of Retina’s Function and Evoked Activity of

Central Visual Structures Under Microwave Irradiation 86

E.N. Panakhova, T.M. Agayev, A.A. Mekhdiyev and A.A. Sadiyeva

Mathematical Modelling of Vagus Nerve Stimulation 92

Bartosz Sawicki, Robert Szmurło, Przemysław Płonecki, Jacek Starzyński,

Stanisław Wincenciak and Andrzej Rysz

Immunotropic Influence of Low Dose Ionizing Irradiation and Microwaves

Applied Sequentially on Human Blood Mononuclear Cells in vitro 98

W. Stankiewicz, M.P. Dąbrowski, A. Cheda, E. Nowosielska,

J. Wrembel-Wargocka, R. Kubacki, M. Janiak and S. Szmigielski

Chapter 3. Electromagnetic Field and Biology

Oxidative and Immune Response in Experimental Exposure to Electromagnetic

Fields 105

Dana Dabala, Didi Surcel, Csabo Szanto, Simona Miclaus,

Mariana Botoc, S. Toader and O. Rotaru

Acoustic/Magnetic Field Assisted Perfusion Study 110

A.H.J. Fleming, E.B. Bauer, R. Bergeron, M. Dahle and J. Enge

Effect of Pulsed Magnetic Field on Fresh Keeping of Vegetables 116

Taiki Hori, Koji Fujiwara, Yoshiyuki Ishihara, Toshiyuki Todaka and

Masao Nakajima

Mutagenicity and Co-Mutagenicity of Strong Static Magnetic Field in Yeast Cells 122

Masateru Ikehata, Sachiko Yoshie, Sachi Matsumoto, Yuji Suzuki and

Toshio Hayakawa

Model for Investigation of Microwave Energy Absorbed by Young and Mature

Living Animals 126

Roman Kubacki, Jaromir Sobiech and Edward Sędek

A Dosimetric Study for Experimental Exposures of Vegetal Tissues to

Radiofrequency Fields 133

Simona Miclăuş and Mihaela Răcuciu

ix

Non-Thermal, Continuous and Modulated RF Field Effects on Vegetal Tissue

Developed from Exposed Seeds 142

Mihaela Răcuciu, Simona Miclăuş and Dorina E. Creangă

Chapter 4. Computer Simulation in Bioelectromagnetics

Three-Dimensional Modelling of Extremely Low Frequency Thin Conducting

Screens 151

Piergiorgio Alotto, Massimo Guarnieri, Federico Moro and Roberto Turri

The Influence of Shape of the Body on SAR Coefficient in the Biological Object 157

Katarzyna Ciosk and Andrzej Krawczyk

A Transmission Line Scale Model for Characterizing Electric and Magnetic Fields 162

Jaime Estacio, Adolfo Escobar, Guillermo Aponte and Héctor Cadavid

Reducing Computational Time in Obtaining 3D Magnetic Field Distributions

Emanated from Very High Voltage Power Lines 168

Carlos Lemos Antunes, José Cecílio and Hugo Valente

LMAT_SIMAG – The Magnetic Field Numerical Calculator of the Package

LMAT_SIMX for Very High Voltage Power Lines 176

Carlos Lemos Antunes, José Cecílio and Hugo Valente

Montecarlo Evaluation of Long Term Exposure to ELF Magnetic Fields from

Independent Power Lines 188

Giovanni Lucca

Medical Image Segmentation Hybrid Algorithm Based on Otsu Method and

Markov Random Fields 198

R. Ludwiczuk and P. Mikolajczak

The Influence of Electromagnetic Field Polarization on Interfering Voltage at

Cardiac Pacemaker Implanted into Human Body Model 207

Arkadiusz Miaskowski, Andrzej Krawczyk, Andrzej Wac-Wlodarczyk and

Yoshiyuki Ishihara

Effects of Dielectric Properties on Radiofrequency Exposure Compliance Using

an Alternative Human Head Model 213

Maia Sauren, Raymond J. McKenzie and Robert L. McIntosh

Finite Element Dosimetry of Power Frequency Induced Currents into the Human

Body by Using Quasi-Static Zooming 221

Riccardo Scorretti, Le Ha Hoang, Nöel Burais and Alain Nicolas

Chapter 5. Electromagnetic Field in Standards and Policy

Electromagnetic Fields Measurements – Methods and Accuracy Estimation 229

Pawel Bienkowski

Cardio-Vascular Homeostasis and Changes in Geomagnetic Field, Estimated by

Dst-Index 238

S. Dimitrova

x

Progress in the ITU Work Concerning Protection Against Radiation 244

Fryderyk Lewicki

A Verification of Quality and Efficiency of Therapeutical System Using

Electromagnetic Field 249

Mira Lisiecka-Biełanowicz, Andrzej Krawczyk and Adam Lusawa

Implantable Cardioverter Defibrillator and UMTS Telephones Interaction 255

Anna Plawiak-Mowna and Andrzej Krawczyk

Finishing the German Mobile Telecommunication Research Programme (DMF) 260

Blanka Pophof, Monika Asmuss, Cornelia Baldermann, Anne Dehos,

Dirk Geschwentner, Michaela Kreuzer, Christiane Pölzl,

Gunde Ziegelberger and Rüdiger Matthes

The Effect of MRET Polymer Compound on SAR Values of RF Phones 264

Igor V. Smirnov

Assessment of the Results of Tightening the Regulations in the Scope of

Protecting the Environment Against the Effects of Electromagnetic Fields

with a Frequency of 50 Hz 269

Marek Szuba

Author Index 277

General Papers

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Some Remarks on Life and Achievements

of Heinrich Rudolph Hertz on His 150th

Birth Anniversary

Agnieszka BYLINIAK, Andrzej KRAWCZYK

Central Institute for Labour Protection – National Research Institute, Warsaw, Poland

Abstract. In this paper a biographical draft of an eminent German physicist,

Heinrich Rudolf Hertz, has been presented. His tremendous contribution to the

development of the science of electromagnetism has been underlined with special

attention paid to the experimental verification of the crucial and turning point

James Clark Maxwell theory.

Keywords. Heinrich Rudolph Hertz, electromagnetic wave, wireless

communication

Introduction

It seems to be an undisputable fact that Heinrich Hertz (1857-1894), a German scientist

and engineer, was an undoubted hero of the history of electromagnetism, and speaking

precisely, its application to telecommunication. Looking at the photograph of the

scientist (Figure 1) one can see a face of a noble and solemn man! One should be

surprised to hear that he was only 37 at the time of his death. His creative attainments

realised in such a short time, and additionally interfered with numerous and serious

illnesses, might become a fascinating topic for those who are interested in plumbing the

mysteries of human potential.

Figure 1. Heinrich Rudolph Hertz

____________________________________

Corresponding Author: Andrzej Krawczyk, Central Institute for Labour Protection - National Research

Institute, Czrniakowska 16, 00-701 Warszawa, poland, e-mail: [email protected]

Electromagnetic Field, Health and EnvironmentA. Krawczyk et al. (Eds.)IOS Press, 2008© 2008 The authors and IOS Press. All rights reserved.

3

1. Short Biography

As a schoolboy he had already revealed a distinguishing capabilities not only in

sciences but in humanities as well. He read Plato and Greek tragedies in their original

versions. He also willingly quoted Homer and Dante, as one of his biographers states

[1]. He also studied other subjects with great passion; he shone at practical activities

during which demonstrated his avocation for modelling, sketching or for very tangible

occupations like carpentry or turnery. There is an anecdote referring to this: a craftsman

instructing him in turnery once exclaimed having learnt about his professorship

nomination: What a great pity – but that boy could have become a turner worth his salt.

Perhaps his passion for practical occupations contributed to his future decision of

taking up engineering and studies at Dresden Technical University. However, he soon

recognised that his true love was physics, and not technical subjects, so he moved to

Berlin University where – for several years- he studied physics with such great

scientists as Gustav Kirchoff (1824-1887) and Hermann von Helmholtz (1821-1894).

This latter one soon appreciated that young man’s talent and intellectual capabilities.

Young Hertz is appointed a difficult problem to be solved, namely he was supposed to

determine the mass of electrical carriers. The young scientist made the original

instruments necessary for carrying out the experiment by himself. In 1879 he received

an award from the department of philosophy both for the successful experiment and

dissertation. A year later he is happy with another success. It is his theoretical

dissertation on rotating balls in electromagnetic field for which he is admitted his PhD

being only 23 years old (Figure 2).

Figure 2 Title page of Hertz’s doctor’s dissertation

Soon, at the age of 28, he receives the chair of physics at Karlsruhe Technical

University where, for the first time, he experimentally confirms the existence of

electromagnetic waves predicted twenty years earlier by a Scottish scientist John Clerk

Maxwell. The year 1888 is an essential date for Hertz as then he finally verifies

A. Byliniak and A. Krawczyk / Some Remarks on Life and Achievements of Heinrich Rudolph Hertz4

Maxwell’s theoretical considerations on electromagnetic field. In his laboratory Hertz

constructed – all by himself – a transmitting and receiving system. The source of

electrical oscillations was an oscillator, and the receiver – a resonator (Figure 3).

Placing the resonator in different positions he managed to measure the length of

electromagnetic waves. He also determined their speed – it turned out that it was close

to that theoretically computed by Maxwell and equals ca. 300 000km/s. The results of

the experiment became the evidence of the existence of electromagnetic wave that

travels in a vacuum with the light speed.

Figure 3 Hertz’s experiment: up– setup, down - scheme

One should regret very much that Hertz was not able to properly appreciate the results

of his experiment. There is again an anecdote referring to it. Once his students at the

University of Bonn were impressed, and wondered what use might be made of this

marvelous phenomenon. Hertz explained It's of no use whatsoever; this is just an

experiment that proves Maestro Maxwell was right, we just have these mysterious

electromagnetic waves that we cannot see with the naked eye. But they are there. One

of his students insisted: So, what next?. Hertz shrugged and modestly answered:

Nothing, I guess. Fortunately, his contemporaries did not share his skepticism. The

English mathematical physicist, Oliver Heaviside (1850 – 1925), said in 1891: Three

years ago, electromagnetic waves were nowhere. Shortly afterward, they were

everywhere. Guglielmo Marconi (1874 - 1937) in his youth read the Hertz article and

it inspired him immediately to use Hertz's spark oscillator for signaling. And he

realized this idea in introducing radio transmission.

In his sequential works Hertz examined properties of electromagnetic waves. In

his experiments he gave evidence for optical properties of electromagnetic waves, i.e.

A. Byliniak and A. Krawczyk / Some Remarks on Life and Achievements of Heinrich Rudolph Hertz 5

for their ability to travel along straight lines, as well as for their refraction and

polarization.

2. Death and afterwards

That interesting and happy period of Hertz’s life did not last long. Since 1889, when he

took up his important post at the chair of Bonn University, he started having serious

health problems. Initially the symptoms did not interfere much with his scientific work;

however, while becoming more and more serious, they caused that he gave up his

research, resigned from his post, stopped conducting university lectures, and they

finally led to his too early death. Heinrich Hertz died of blood poisoning on 1 January

1894 in Bonn, and has been buried in the Jewish cemetery in Ohlsdorf, Hamburg,

Germany (Fig.4).

When Hertz died in Bonn, Germany, in 1894, Sir Oliver Lodge (1851 -1940),

British physicist and writer, gave Hertz credit for accomplishing what the great English

physicists of the time were unable to do. It was not hard to give Hertz credit. Not only

had he established the validity of Maxwell's theorems, he had done so with a winning

modesty. And it is worth quoting the passage from one eulogist’s funeral speech: ...he

was a noble man who had the singular good fortune to find many admirers, but none to

hate or envy him; those who came into personal contact with him were struck by his

modesty and charmed by his amiability [3].

Figure 4 Hertz’s grave and his signature

Heinrich Hertz’s experiments confirmed the existence of electromagnetic waves

which travel in the air at a very high speed. It is the discovery without which one

cannot imagine contemporary telecommunication. Radio, TV, cellular phones and all

other kinds of telecommunication equipment would lose their raison d’etre without this

knowledge introduced to the scientific culture by the hero of our essay. His

contribution to the scientific heritage was acknowledged by the international society.

His name was given to the frequency unit – Hertz (Hz). IEC took the decision in 1930.

A. Byliniak and A. Krawczyk / Some Remarks on Life and Achievements of Heinrich Rudolph Hertz6

References

[1] Susskind, Charles, "Heinrich Hertz : a short life". San Francisco Press, 1995

[2] http://www.sparkmuseum.com/hertz.htm

[3] http://www.wsone.com/fecha/hertz.htm

A. Byliniak and A. Krawczyk / Some Remarks on Life and Achievements of Heinrich Rudolph Hertz 7

New Horizon in Biomagnetics and

Bioimaging

Shoogo UENO1

Department of Applied Quantum Physics, Graduate School of Engineering,

Kyushu University, Fukuoka 812-8581 Japan

Abstract. New developments in the fields of biomagnetics and bioimaging have

enabled the non-invasive brain-function measurement and localization of several

human brain functions such as cognition, memory and learning. At the same time

new biophysical phenomena such as cell and macromolecular alignment under

strong magnetic fields and cancer therapies via magnetic nanoparticles and

hyperthermia have opened new paths for biomedical engineering, cancer and

immunological treatment. This paper presents a review on the recent work of our

group in the topics of transcranial magnetic stimulation (TMS), magnetic

resonance imaging (MRI), magnetoencephalography (MEG), cancer therapy and

cell orientation.

Keywords. electromagnetic field, biomagnetism, magnetotherapy, magnetic

resonance imaging, transcranial magnetic stimulation.

Introduction

Biomagnetics is a multidisciplinary research field that studies the interactions between

living organisms and magnetism. It combines a wide range of disciplines from

medicine and biology to physics and engineering to investigate the principles of

interaction between biological cells and macromolecules while dealing with the

repercussions and possible applications arising from these principles. As an example of

these applications there are the localized and vectorial transcranial magnetic

stimulation (TMS), the development of bioimaging technologies such as functional

magnetic resonance imaging (MRI) and magnetoencephalography (MEG), the

alignment of diamagnetic cells for tissue regeneration, and innovative cancer therapies.

The TMS has enabled us to obtain non-invasive functional mapping of the human brain

[2,3] and has therapeutic effects for several diseases such as mental illnesses, ischemia,

and cancer [4-10].

On the other hand, MRI and MEG enabled us to identify the locations of human brain

functions [11] but, despite these new technologies, it is still difficult to understand the

dynamics of brain functions, which include millisecond-level changes in functional

regions and dynamic relations between brain neuronal networks (Figure 1). It is for

1

Corresponding Author: Shoogo Ueno, Graduate School of Engineering, Kyushu University, 6-10-1

Hakozaki, Higashi-ku, Fukuoka, 812-8581 Japan, Email: [email protected]

Electromagnetic Field, Health and EnvironmentA. Krawczyk et al. (Eds.)

IOS Press, 2008© 2008 The authors and IOS Press. All rights reserved.

8

these reasons that we are also developing new bioimaging methods to visualize

neuronal electrical activities and electrical conductivities in the brain [12-15].

On the cell manipulation and medical engineering front, we make use of the

technological advances in superconducting magnets to study diamagnetic forces on

biological macromolecules and cells. This diamagnetic force causes magnetic

orientation of macromolecules and cells, which has potential applications in

regenerative medicine [16,17].

In this paper, recent advances in biomagnetics and bioimaging for medical applications

are reviewed and discussed based on the results obtained mainly in our laboratory.

1

3

DC

10

-15

10

-12

10

-9

10

-6

10

-3

1

10

3

10

6

MRI Magnet

Magnetophosphene

Urban Magnetic Fields

Magnetic Storm

Earth

SQUID

Frequency of Magnetic Field

(Hz)

101010

Magnetic Stimulation

of the Heart (τ =1ms)


of the Brain (τ =0.1ms)

Blood Flow Change via


of Sensory Nerves

Magnetic Orientation

Ma

gn

etic

F

lu

x D

en

sity (T

)

Heart (MCG)

Brain (MEG)

Evoked Fields

Brain Stem

Lung (MPG)

6 9

Parting of Water

Mobile Telephone

ELF

Consumer Electronics

Ca Release

2+

Hyperthermia

Sensitivity

Figure 1. Various biomagnetic phenomena observed at different frequencies and magnetic field intensities

1. Transcranial Magnetic Stimulation

In transcranial magnetic stimulation a pulse of a strong magnetic field is used to

generate eddy currents and stimulate the brain or the nervous system. However, when

using a single coil to do it, the area of stimulation is not well defined. We therefore

devised a method of localized brain stimulation using a figure-eight coil [2] (see Figure

2). When a strong electric current is applied to a figure-eight coil over the head for 0.1

ms, a pulsed magnetic field of 1 T is produced. To confirm the better localization of the

stimuli using this method, we calculated the spatial distributions of the eddy currents

using the finite-element method [4] for figure-eight and circular coils of 50, 75, 100

and 125 mm. The brain surface under the intersection of the figure-eight coil exhibited

high current density whereas the circular coils induced more widespread eddy currents,

which makes of the figure eight coil a more precise and accurate tool.

S. Ueno / New Horizon in Biomagnetics and Bioimaging 9

TMS is a useful method both to examine non-invasively brain functions and to operate

biological changes. In particular, it is convenient to examine dynamic brain function

without causing any pain, producing so-called “virtual lesions” for a short period of

time. We have successfully used this method to noninvasively evaluate the cortical

reactivity and functional connections between different brain areas. In our study, we

considered an associative memory task involving pairs of Kanji (Chinese) pictographs

and unfamiliar abstract patterns [3]. Given that the subjects were Japanese adults fluent

in Kanji, only the abstract patterns represented novel material. During memory

encoding, TMS was applied over the left and right dorsolateral prefrontal cortex

(DLPFC). Robust interference by TMS represents substantial evidence that the right

DLPFC is important to encoding non-verbal materials. A significant (P < 0.05)

reduction in subsequent recall of new associations was seen only with TMS over the

right DLPFC. This result suggests that the right DLPFC contributes to encoding of

visual-object associations and is consistent with a material-specific rather than a

process-specific model of mnemonic function in DLPFC.

Figure 2: Basic principles of magnetic stimulation using a figure-eight

coil. (a) A figure-eight coil on the head. (b) A single ring coil and an

induced current pattern. (c) A figure-eight coil and an inducedcurrent

pattern. After reference 2.

S. Ueno / New Horizon in Biomagnetics and Bioimaging10

Recently, repetitive TMS (rTMS) has also become an increasingly important

therapeutic tool for the potential treatment of neurological and psychiatric disorders.

We have employed a pulsed magnetic stimulator used in repetitive transcranial

magnetic stimulation (rTMS) for the treatment of treatment of lesions caused by

dopaminergic neurotoxins associated with Parkinson’s disease. The magnetic field

peaks were set to 0.75 T (< motor threshold) and 1 T (> motor threshold) for a duration

of up to 238 μs. The lesions were induced in the brains of adult male Wister rats and

the effect of rTMS on injured neurons was investigated in the rat brain after

administration of the neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)

[7]. The rats received rTMS (10 trains of 25 pulses/s for 8 s) 48 h after MPTP injection.

Tyrosine hydroxylase (TH) and NeuN expressions were investigated in the substantia

nigra. The functional observational battery-hunched posture score for the MPTP-rTMS

group was significantly lower and the number of rearing events was higher compared

with the MPTP-sham group, results suggesting that rTMS reactivates the dopaminergic

system in the brain. Long-term potentiations (LTPs) were observed in both the TMS

stimulated and sham control groups. The maintenance phases of LTP (from 10 min

after tetanus stimulation to 60 min) of the 0.75 T stimulated group (267+-26%) was

significantly enhanced compared with the sham control group (212+-10%) whereas

there were no significant differences between the maintenance phases of LTP of the

1.00-T stimulated group (223+-13%) and the sham control group (199+-13%). In

contrast, when the rat brain was stimulated by 1.25-T, the LTP was suppressed,

suggesting that the effect of rTMS on LTP depends on the stimulus intensity.

After hippocampus slices were exposed to ischemic conditions (blood-oxygen

deficiency), LTP was induced. The LTP of the stimulated group was enhanced

compared with the LTP of the sham control group in each ischemic condition. The

rTMS acted as a preconditioning treatment, being effective when delivered before

ischemia occurs. The rats received rTMS 48 h after MTPT injection, and tyrosine

hydroxylase (TH) and NeuN expressions were investigated in the substantia nigra to

examine the possibility of TH positive mediation. Neuronal survival in the substantia

nigra pars compacta (SNpc) was evaluated by double labelled (TH, NeuN)

immunofluorescence microscopy. The loss of nigral TH+dopaminergic neurons was

significantly prevented in the MPTP-rTMS group (62.9+-3.0) compared with the

MPTP-sham group (14.8+-2.0). The number of surviving dopamine neurons in the

MPTP-sham rats was significantly smaller than in the SNpc of undamaged rats. In

contrast, the number of surviving neurons in the MTPT-rTMS group was significantly

larger than in the MTPT-sham group. Our results show proof that the rTMS treatment

rescues injured dopaminergic SN neurons from cell death due to MTPT toxicity.

2. Magnetoencephalography

MEG is a technique to measure the very weak magnetic fields generated by neuronal

currents. These biomagnetic fields are measured by a superconducting quantum

interference device (SQUID), which detects changes in a magnetic field as weak as 5

fT, with a millisecond temporal resolution. We compared this method with the

established electroencephalographic technique by using to both techniques to measure

the event-related potential P300 [11]. Multiple equivalent current dipoles were

estimated from the P300 and P300m waveforms obtained from visual and

somatosensory oddball paradigm tasks. Estimated sources from P300m were located on


both sides of the occipito-temporal gyrus for visual stimuli and on the post-central

gyrus for somatosensory stimuli. The sources of P300m were modality specific. The

equivalent current dipoles of P300 were located on the cingulated gyrus and the

thalamus in addition to the locations estimated from P300m. However, the dipoles of

P300m in MEG were not located on the cingulated gyrus and the thalamus. The

discrepancy between EEG and MEG was due to the difficulty to measure radially

oriented dipoles in MEG.

MEG is a good tool for the recognition of patterns on the brain, and in our laboratory

we have used it to successfully identify the activated area for an early negative

component which seems to be associated with pattern recognition processes. This was

done by measuring the magnetic fields by comparing the timing and MEG of the

negative component obtained when the discrimination of visually presented letters

required only the identification of a geometric feature with the brain magnetic fields

obtained when the visually presented letters were selected on the basis of their sounds.

The geometric discriminative response task involved only the processing of the visual

configuration of the letters, whereas the phonetic discriminative response task required

an additional grapheme-to-phoneme conversion. The results of this study reflect the

postulated differences in cortical processing entailed in the GDRT and PDRT tasks.

Furthermore, our laboratory has also been involved in magnetoencephalographic

measurements during two types of mental rotations of three-dimensional objects, where

the results indicate that the parietal association area has an important role for the

visualization of hidden parts of visual stimuli [18].

3. Magnetic Resonance Imaging

Estimation of conductivity distributions in the brain is essential for various analyses in

biomedical engineering, such as obtaining current distributions in electric stimulation

and magnetic stimulation, calculating the absorption of electromagnetic waves from

mobile phones, and current-source estimations in EEG and MEG. We have developed

three different methods to obtain conductivity distributions in the human brain using

MRI, allowing to visualize in vivo the electrical properties of tissues without the need

to attach electrodes to the surface of the body and without requirements for

complicated image processing.

The proposed three different methods for conductivity imaging via MRI are the

following: i) a large flip angle method, ii) a third coil method and iii) based on

diffusion tensor MRI [12,13,19].

i) When conductive tissues are subjected to an RF field in MRI, eddy currents are

induced, which results in a reduction of the net RF fields. By this shielding effect, the

flip angles (i.e., nutation angles of the macroscopic magnetization of excited spins) are

reduced in varied degrees, depending on the electrical characteristics of the tissues.

When a precise 180, 360 or 540 excitation pulse is applied to conductive tissues, the

tissues do not yield a signal due to the absence of the transversal components of

magnetization. Meanwhile, resistive tissues yield signals because they are less

electrically shielded than conducting tissues and simultaneously undergo different flip

angles. Also, the resistive tissues leave transversal components with magnitudes

determined by the sine wave functions of flip angles. The difference in signal, therefore,

reflects the conductivity of tissues.


ii) To obtain a conductivity-enhanced images at an arbitrary frequency, an additional

time-varying field parallel to the main static field B0 can be introduced via a third coil.

By the perturbing field or Bc field, slice positioning of the image is affected, and the

slice selection fluctuates. Spatial information in the read-out and phase-encoded

directions are also affected. Conducting tissues are less affected by Bc field, because of

the shielding effects and conductivity-enhanced images can be obtained at any

frequency but in the direction perpendicular to the Bc field.

iii) The diffusion components of biological tissues are usually divided into a fast and a

slow component. Thanks to the proportionality between conductivity and diffusion

coefficient, we can estimate the tissue conductivity by measuring the fast diffusion

component, which corresponds to diffusion in the extracellular fluid.

Figure 3: Color map of the conductivity in the brain as measured by the

conductivity MRI method iii) described in the text. The intensities of red,

green, and blue are proportional to the conductivities in the anterior-

posterior, right-left, and superior inferior directions, respectively. From

reference 19.

All the described methods lead to qualitative in vivo MRI conductivity imaging of brain

tissues in rats and humans without the need of invasive techniques. Furthermore, using

the third method the spatial distribution of anisotropic conductivity of the human brain

was obtained. We observed that the gray matter did not have a clear dependence of

conductivity on direction, whereas the internal capsule and the corpus callosum had

higher values of mean conductivity and anisotropy (Figure 3). This anisotropy is

attributable to the anatomical structures of these regions, diffusion of water molecules

in the extracellular fluid is disturbed by the cell membranes, and the fact that

diffusibility is higher in the direction of neuronal fibers than in other directions.


4. Magnetic Cancer Therapy

From the combination of nanotechnology and magnetism aroused the original

technique of magnetic hyperthermia as cancer treatment, where magnetic nanoparticles

irradiated with radio frequency magnetic fields are used to increase the temperature of

a tumoral region [20]. Our laboratory has explored two other different approaches to

cancer therapy via the magnetic forces acting on functionalised magnetic beads and the

use of pulsed magnetic stimulation. The first method makes use of magnetic beads

functionalised to attach to specific (tumoral) cells and moving along the field gradients

generated by magnetic pulses to destroy these cells [8]. We combined TCC-S leukemic

cells with magnetizable beads (diameter = 4.5 ± 0.2 μm, magnetic mass susceptibility =

(16.3 ± 3) x 10-5 m3

/kg). After combination the cell / bead / antibody complexes were

placed on a magnet for enough aggregation. The aggregated beads were then stimulated

by a circular-shaped coil which produced a maximum of 2.4 T at the center of the coil.

After stimulation, the viability of the cells was measured, and the cells were observed

under a scanning electron microscope. The viability of the aggregated and stimulated

cell / bead /antibody complexes was significantly decreased, and the cells were

destructed by the penetration of the beads into the cells or rupturing of the cells by the

beads (Figure 4). We hypothesize that the instantaneous pulsed magnetic forces cause

the aggregated beads to forcefully penetrate or rupture the targeted cells. The magnetic

force acting on any particular material is proportional to the magnetic field, magnetic

field gradient, and the magnetic susceptibility of the material. When the nanoscale

particles inside the beads are closely assembled, the magnetic mass susceptibility is

sufficiently high to force the attachment of the beads to the cells by the magnetic force.

The magnetic force acting on the aggregated beads was strong enough to shift the beads

and damage the cells.

Figure 4: Scanning electron micrographs of the cell/bead/antibody

complexes with and without pulsed magnetic stimulation. (a) The non

magnetically stimulated cell/bead/antibody complex was not damaged. (b)

The stimulated cell/bead/antibody complexes were damaged by

penetration of the beads. Scale bars ¼ 4:5 μm. After reference 8.

To consider whether magnetic fields could have a therapeutic effect on their own right

and without using magnetic beads or nanoparticles, we investigated the effects of

repetitive magnetic stimulation on tumors and immune functions [9, 10]. Magnetic

stimulations were applied from a circular coil with the following conditions: peak

magnetic field = 0.25 T (at the center of the coil), frequency = 25 pulses / sec, 1000


pulses / sample/ day and magnetically induced eddy currents in mice = 0.79-1.54 Am-2

.

Our tumor growth study showed a significant tumor weight decrease due to the

application of magnetic stimulation (54 % vs. the sham group).

An immunological assay was also performed to examine the effects of the magnetic

stimulation on immune functions. The in vivo study measured the production of

apoptosis related cytokines (tumor necrosis factor) TNF-α and IL-2 in the spleen after

exposure to the magnetic stimulation for 3 or 7 times. We found that TNF-α production

significantly increased in the stimulated group (146-164 % vs. the sham group). In an

in vitro study, isolated spleen cells (lymphocytes) were exposed to the magnetic

stimulation (25 pulses/sec, 1000 pulses per sample, and eddy currents: 2.36-2.90 A/m2

)

and a proliferation assay was performed. The proliferation activity of the lymphocytes

was upregulated in the exposed samples. These results indicate that the immune

functions might be activated by repetitive magnetic stimulation exposure, resulting in a

tumor weight decrease.

5. Magnetic Control of Cell Orientation

When diamagnetic materials such as fibrin, collagen, osteoblasts, epithelial, Schwann

and smooth muscle cells are exposed to static magnetic fields of T order, these

materials align either parallel or perpendicular to the direction of the magnetic field due

to the magnetic anisotropy of the materials [21] (Figure 5). This phenomenon offers

particular interest for biomedical engineering applications in tissue regeneration, such

as bone formation and nerve re-growth, the two examples we have studied and relate

next.

The introduction of bone formation to an intentional orientation is a potentially viable

clinical treatment for bone disorders [16,22]. We have investigated the effects of static

magnetic fields of 8 T on bone formation in both in vivo and in vitro systems [16].

After 60 h of exposure to the magnetic field, cultured mouse osteoblastic MC3T3-E1

cells were transformed to rod-like shapes and were oriented in the direction parallel to

the magnetic field. Although the magnetic field exposure did not affect cell

proliferation, it upregulated cell differentiation and matrix synthesis as determined by

alkaline phosphatase and Alizarin red stainings, respectively. The magnetic fields also

stimulated ectopic bone formation in and around subcutaneously implanted bone

morphogenetic protein-2 (BMP-2) containing pellets in mice, in which the orientation

of bone formation was parallel to the magnetic field. Strong magnetic fields have the

potency to stimulate bone formation as well as to regulate its orientation in both in vitro

and in vivo models. We propose that the combination of strong magnetic fields and a

potent osteogenic agent such as BMP may possibly lead to an effective treatment of

bone fractures and defects.

On the nervous system, Schwann cells aid in neuronal regeneration in the peripheral

nervous system by guiding the regrowth of axons. We have found that it is possible to

guide the growth of Schwann cells by exposing them to 8 T magnetic fields, or

cultivating them in magnetically oriented collagen gels [17]. We have also successfully

used this magnetic control of Schwann cell alignment as a nerve regeneration technique

in tissue engineering and regenerative medicine. Sciatic nerves in Wister rats were

transected, and immediately afterwards a silicone tube (1.5 mm in diameter, 15 mm

long) filled with type I collagen was used to bridge the space of the nerve defect as an

artificial nerve graft. Two types of silicone tubes were prepared: one was filled with


randomly oriented collagen fibers as a control, and the other was filled with collagen

fibers oriented magnetically by 2 hours of exposure to 8 T fields. 12 weeks afterwards

the number of regenerated axons was observed by morphological measurements and

the function of the newly generated axons was tested by recording the compound action

potentials in vivo. We observed the sciatic nerve regeneration 12 weeks after

neurotomy in both control and magnetically treated groups. The morphological

examination showed that the numbers and diameters of the regenerated myelinated

fibers in the silicone tubes gave a significant difference between control and

magnetically treated groups. The number of fibers was 373.4 +-27.6 (treated) and 274.0

+-11.7 (control). The diameters of the axons were 5.81 +-0.087 um (treated) and 5.53

+-0.064 um (control). We measured the compound action potentials to evaluate the

functional connection across the silicone tube bridge. The potentials propagated in 2

out of 6 samples in the control group, and in all of the 6 samples of the treated group,

strongly suggesting that a magnetically aligned collagen structure can guide the growth

cone and nerve axon, which results in the acceleration of nerve regeneration.

Figure 5: Magnetic orientation of biological macromolecules and cells

in an 8 T magnetic field. From references 17, 21 and 23.


6. Conclusions

Biomagnetics and bioimaging are thus leading medicine and biology into a new

horizon through the novel applications discussed above. With the increasing integration

of medicine and engineering, biomagnetics and bioimaging are further developing into

a new science that encompasses a wide range of fields, including physics and cognitive

science, integrating their diverse cultures to create a new, original discipline.

Acknowledgment

This study was supported by a Grant-in-Aid for Scientific Research (S) (no. 17100006)

from the Japan Society for the Promotion of Science (JSPS).

The author thanks Masaki Sekino, Mari Ogiue-Ikeda, Hirofumi Funamizu and Yawara

Eguchi, all Ph.D. students at the Deparment of Biomedical Engineering, Graduate

School of Medicine, the University of Tokyo, for their contribution to this research

project.

References

[1] S. Ueno, IEEE Eng. Med. Biol. 18 (1999), pp. 108-120.

[2] S. Ueno, T. Tashiro, and K. Harada, J. Appl. Phys., 64 (1988) pp. 5862-5864.

[3] C.M. Epstein, M. Sekino, K. Yamaguchi, S. Kamiya and S. Ueno, Neurosci. Lett. 320 (2002), pp. 5-8.

[4] M. Sekino and S. Ueno, IEEE Trans. Magn. 40 (2004), pp. 2167-2169.

[5] M. Ogiue-Ikeda, S. Kawato and S. Ueno, Brain Res. 993 (2003), pp. 222-226.

[6] M. Ogiue-Ikeda, S. Kawato and S. Ueno, Brain Res. 1037 (2005), pp. 7-11.

[7] H. Funamizu, M. Ogiue-Ikeda, H. Mukai, S. Kawato and S. Ueno, Neurosci. Lett. 383 (2005), pp. 77-81.

[8] M. Ogiue-Ikeda, Y. Sato and S. Ueno, IEEE Trans. Nanobiosci. 2 (2003), pp. 262-265.

[9] S. Yamaguchi, M. Ogiue-Ikeda, M. Sekino, S. Ueno, IEEE Trans. Magn., 41 (2005), pp. 4182-4814.

[10] S. Yamaguchi, M. Ogiue-Ikeda, M. Sekino, S. Ueno, Bioelectromag. 27 (2006), pp. 64-72.

[11] T. Maeno, A. Kaneko, K. Iramina, F. Eto and S. Ueno, IEEE Trans. Magn. 39 (2003), pp. 3396-3398.

[12] M. Sekino, K. Yamaguchi, N. Iriguchi and S. Ueno, J. Appl. Phys. 93 (2003), pp. 6730-6732.

[13] M. Sekino, Y. Inoue and S. Ueno, Neurol. Clin. Neurophysiol. 55 (2004), pp. 1-5.

[14] M. Sekino, H. Mihara, N. Iriguchi and S. Ueno, J. Appl. Phys. 97 (2005), article #10R303.

[15] T. Hatada, M. Sekino and S. Ueno, J. Appl. Phys. 97 (2005), article #10E109.

[16] H. Kotani, H. Kawaguchi, T. Shimoaka, M. Iwasaka, S. Ueno, H. Ozawa, K. Nakamura and K. Hoshi, J.

Bone Miner. Res. 17 (2002), pp. 1814-1821.

[17] Y. Eguchi, M. Ogiue-Ikeda and S. Ueno, Neurosci. Lett. 351 (2003), pp. 130-132.

[18] H. Kawamichi, Y. Kikuchi and S. Ueno, IEEE Trans. Magn. 41 (2005), pp. 4200-4202.

[19] M. Sekino, Y. Inoue and S. Ueno, IEEE Trans. Magn. 41 (2005), pp. 4203-4205.

[20] R. Hergt, W. Andrä, C. G. d’Ambly et al., IEEE Trans. Magn. 34 (1998), pp. 3745-3754.

[21] S. Ueno and M. Sekino, J. Magn. Magn. Mat. 304 (2006), pp. 122-127.

[22] H. Kotani, M. Iwasaka, S. Ueno et al., J. App. Phys. 87 (2000), pp. 6191-6193.

[23] M. Iwasaka, J. Miyakoshi and S. Ueno, In Vitro Cel. Devel. Biol. Animal (2003), pp. 120-123.


Self-Field Theory:

Analytic Spectroscopy of the Photon

Anthony H. J. FLEMING

Biophotonics Research Institute, Australia. [email protected]

Abstract. Self-field theory (SFT) provides deterministic eigensolutions to the

Maxwell-Lorentz equations for the hydrogen atom where Planck’s constant

2q

4 v0 e

πε

= is the energy per cycle of the principal eigenstate [1]. Based on a

composite (hydrogenic) photon, an analytic expression for photon mass is

obtained2

4

v

e

m c

c

ω

γ

γ

=

, where ωγ

is a discrete photon transition frequency within

each cycle of the electron. This expression is compatible with the fine-structure

constant

2

4m cv

e

c

γ

α

ω

γ

= =

, where

55

0.396 10m kg

γ

−

= × (19

0.221 10 eV

−

× ). Thus there

is a series of eigenstates within individual photons, like the atom, that vary with

the ambient energy density or temperature. Within atoms and molecules, photon

substructure introduces a previously unknown mechanism by which binding

energies can vary between strong and weak structures in variation with the

ambient energy density, or temperature. A range of physical and biological

examples support photon substructure with its associated photon spectroscopy.

Keywords. Self-field theory, quantum field theory, Planck's constant, fine

structure constant, composite photon, photon mass, photon spectroscopy,

Schumann resonance, atomic structure, molecular structure.

1. Introduction

Like quantum mechanics (QM) and quantum field theories (QFTs) in general, SFT is

both an analytic and a numerical method for solving field-particle equations. Unlike

QFTs however, SFT does not involve probabilistic inner products, but rather uses the

Lorentz equation and the virial relationships in addition to Maxwell’s equations to

solve for the periodic dynamic motions. SFT uses the E- and H-fields directly rather

than any derived potential functions and hence gauge and a necessity for any quadratic

functional form is avoided a priori; the field equations are first order rather than second

order. Importantly the E- and H-fields within SFT are not ubiquitous throughout space

as in classical electromagnetics (EM), but are discrete and particulate, albeit of minute

size compared with particles such as electrons, neutrons and protons. The atomic

binding field is not assumed to permeate all space out to infinity or even within the

atom, but it is stream-like, the photons all following each other performing helical

spirals while transiting to and fro between the electrons and the nucleus. The photon,

rather than being a single point particle with a dual wave/particle nature termed a

matter-wave, is assumed to have an internal structure, i.e. is composite, perhaps fractal



18

in nature. It is also assumed to move in two orthogonal directions. This leads to

important mathematical differences to quantum methods and with classical EM. In SFT

mass-point particles are non-singular as they are assumed to always move as physical

spinor1

never residing at their origins, unlike QFTs where probabilistic renormalization

is necessary. Uncertainty is seen as a numerical factor due to the way the photon is

modeled and not, as described by Heisenberg, as a limitation to our knowledge. SFT

can be used in situations where dynamic balances hold between interacting particles as

in the hydrogen atom [1-2].

In the physical world SFT may be able to provide solutions to questions such as

how snow flakes form in such myriad different forms and the reason for the layering

seen within the atmosphere. In biophysics, the shape of the DNA protein varies with

the ambient energy inside a cell. SFT was recently used to examine possible internal

structures of the photon [4-5]. One possible structure of the ordinary photon is

hydrogenic as shown in Fig. 1; two sub-photonic particles termed the ephectron and the

phroton have equal mass and opposite charge. This provides Einstein's photoelectric

energy E hν= and gives the proper continuous energy-frequency response unlike

the discrete physics of the atom where the electron and proton have differing masses.

The sub-photonic E- and H- fields for the two interacting particles are calculated using

a SFT formulation similar to that applied to the hydrogen atom. Except for the equal

masses forming the composite photon, SFT applies to the photon in a similar way it

applies to the hydrogen atom. Hence there is a strong similarity between the photon's

eigenstates and those of the hydrogen atom. The main parameter in the analytic

spectroscopy of the ordinary photon is its mass, similar to the principal mode of the

hydrogen atom where the electron mass specifies the spectroscopy. If the photon mass

is known, the spectroscopy of photons can be examined in detail. The transition

frequencies are expressed in terms of a continuous series,

2 2

1 1

R

m n

γ γ

ν

⎛ ⎞= −

⎜ ⎟

⎝ ⎠

(1)

where, m 1,2,3...= n 2,3,4...= The photon Rydberg number

4 2 3 2

0 o

2 3 2

0 o

q m m (8 ) v

R

8 h c r q

γ γ γ

γ

γ

π ε

ε

= = (2)

is a photon-specific function of mass and charge. These frequencies may be related to

the well-known Schumman frequencies whereby the ionosphere is layered during

sunlight. Other physical applications of photon substructure may include snowflake

design and the buildup of avalanches. These and other phenomenon may enable

mathematical investigation, hopefully empirical support for photon substructure.

1

Dirac spinors can be described as mathematical unitarian spinors whereas SFT spinors are actual motions.

SFT spinors are based on the analytic form of Heinrich Hertz's original potential functions [3].

A.H.J. Fleming / Self-Field Theory: Analytic Spectroscopy of the Photon 19

Figure 1. Photon sub-structure consists of two particles, the ephectron, and the phroton, of equal mass

1

2

m m mγ γ γ

+ −

= = and opposite charge

1

2

q q qγ γ γ

+ −

= = − . Each has two spinorial motions

like the electron and proton in the hydrogen atom.

2. Mass of the Photon

The issue of photon mass has remained unanswered during the past century [6].

Moreover since the early days of QM, molecular structure has been studied using QM

primarily as a numerical tool [7]. At the same time important theoretical problems such

as the theory of the covalent bond of H2 remain. In the SFT analysis of the hydrogen

atom, the atom was modelled mathematically via two point-mass particles, the electron,

and the proton, an extension to the early Bohr model [1]. The eigenstructure of the

hydrogen atom forms into two balanced halves, one is a balance between the electron

and the E- and H-fields as shown below in Eq (3); another half, not shown, but

identical in form, balances the proton with the fields. The overall structure thus

involves the electron and the proton on the left hand side, with the photon on the right

hand side. It is seen that the sides consist of moving particles and hence the concept of

elastic collisions emerges between the electron with a stream of photons, and the

proton with the same stream of photons.

e

e

V1 0

T0 1

ω

ω

⎡ ⎤⎡ ⎤ ⎡ ⎤

=⎢ ⎥⎢ ⎥ ⎢ ⎥

⎣ ⎦ ⎣ ⎦⎣ ⎦

(3)

Planck’s constant

2

0 e

q

4 vπε

= , the energy per cycle of the principal eigenstate,

depends on the motions of the electron, proton, and photon; all are involved in the

ro

ro

q

+

γ

rc

m+

γ

rc

q

-

γ

m-

γ

A.H.J. Fleming / Self-Field Theory: Analytic Spectroscopy of the Photon20

atom's dynamic balance. The photon performs many relativistic transitions back and

forth between the proton and electron within each cycle of the electron and proton that

rotate coherently about their centre of mass. Since the photon must perform a discrete

number of transits per cycle for the atom's energy to be preserved this suggests

collisional based polygonal rotations for both the electron and proton rather than the

assumed circular rotations given by spinor theory and used by both SFT and QFTs. The

phase length of the photon each time it transits

2

πwill maintain the overall periodicity

of the atom providing a method for analytically comparing the energy of the photon

with that of the electron2

4

e

v

m c

c

γ

γ

ω

=

, where

γ

ω is the collision frequency of the

photon. Assuming a polygonal motion circumscribes a circle representing the Bohr

mageton, the photon collision frequency is estimated as 54 from the known value of the

Landé g-factor. Thus mγ

evaluates to 55

0.396 10 kg

−

× (19

0.221 10 eV

−

× ). The

analytic expression for the photon mass is compatible with the expression for the fine-

structure constant

2

4e

m cv

c

γ

γ

α

ω

= =

. The numerical value for m

γ

is compatible with

the experimental estimates for the lower limit mass listed by the Particle Data Group

[8].

3. Discussion: The Role of the Photon in Microbiology

Cells are fundamental building blocks of tissues and operate in concert with a range of

other tissue-specific components. The extra cellular matrix (ECM) can comprise

structural and connection fibres between and within cells. Cells are a community of

individual entities sharing their energies via cell dynamics and cell-to-cell

communication of photons and in addition to the ECM, other short-range mechanisms.

Cells thus adapt their individual energy states as the cell cycle proceeds; some cells die

while others replicate. The state of a cell at any time depends in part on the health of

the surrounding tissue. The photon mechanism investigated within this report reveals

that the energy of the EM binding field within DNA may well control the strength and

elasticity of the protein that is observed to vary across the cell cycle. As the energy of

the intracellular medium changes, the bond becomes more rigid, less able to coil.

Metaphase is one point in the cell cycle where the bonds across the bases are ready to

become disassociated in forming the two daughter chromatids. Part of DNA’s structure

involves hydration between bases across its internal core. The continuous nature of the

photon's energy creates a precipitous reaction as the energy finally reaches a point

where the photon's internal dynamics changes abruptly from one spin state to another

resulting in the bond being wrenched apart. These hydration states of DNA may be

fundamental to the cell cycle. The photon transition energies may act as 'triggers'

within the cell cycle. At the same time as this binding energy reaction process occurs

in chromosomes, surrounding cells polarize causing proteins to diffuse within the cell

membranes allowing electrostatic fields to form within the cell and an electric gradient

between the spindle poles, similar to a capacitor. Energy is pumped into the cell via this

polarization mechanism. Under the electric gradient, the chromosome begins to stretch


out to its full molecular reach. This may be due to the photon states gradually causing

the hydration bonds to assume a form akin to a liquid crystal. This represents a major

difference between in vivo and in vitro cell reactions. At the same time, this photon

mechanism may be responsible for the observed efflux of photons from DNA

strands [9].

Motions of proteins within the cell membrane in part control the energy state of the

DNA. The dielectric response of cells is a polarization process of diffusing proteins

within the membrane, and also a rotation of these same proteins. The dielectric

response of tissues is predominantly dipolar at ELF frequencies when most of the cells

align in a similar direction without many rotations occurring. As the external

frequency of a perturbing field is raised to RF for instance, rotational motions within a

cell’s membrane increase and the average polarization across a tissue decreases due to

these rotational diffusions. These frequencies can be related to the complex dielectric

constants. External EM fields thus perturb the endogenous cell dynamics.

No single photon energy or frequency drives all cells in a tissue. A set of

frequencies maps out how a tissue can remain viable, or conversely fall into disrepair,

depending on the overall management of the cells over the entire tissue. As each cell

develops, it has a specific set of frequencies that are associated with the bases of the

DNA code within the cell cycle. As the energy in the cell drops, each specific

frequency is engaged. In apoptosis the cell frequency becomes chaotic. So each cell is

in a particular state at any time. The overall tissue frequency is a weighted average over

the complete tissue. This is a macroscopic quantity whereas the DNA in each cell has a

specific photon frequency state, or binding energy state.

In time a degenerative action (aging) may occur via hydration states. In keeping

with the cellular mechanisms discussed above, both the intracellular and extracellular

components of tissues operate within certain energies or frequency bands causing

hydration binding to become important aging factors if the energy associated with the

tissue diminishes over time. Stiffening of joints and limbs may be related to a lowering

of the photonic energy states within the hydration bonds associated with proteins and

the ECM.

4. Conclusion

This report gives insight of the role of the photon as the binding energy of atoms and

molecules. Discussed is a previously unknown discrete process by which the photon

transits between electron and nucleus. This photon transit mechanism appears related

to a number of energy or temperature dependent processes where bonds range between

strong and weak structures. Physical processes such as the ionospheric layering and

biological processes such as the cell cycle may well involve photons of specific energy

states.

References

[1] A. H. J. Fleming, Electromagnetic self-field theory and its application to the hydrogen atom, Physics

Essays, vol. 18, 3, 2005.

[2] W. Heisenberg, The physical principles of the quantum theory, Dover, New York, NY, 1949.

[3] A. Von Hippel, Dielectrics and waves, John Wiley & Sons, New York, NY, 1962.

A.H.J. Fleming / Self-Field Theory: Analytic Spectroscopy of the Photon22

[4] A. H. J. Fleming, E. B. Colorio (nee Bauer), A Predicted Photon Chemistry, BEMS-26, Washington

DC, June 2004.

[5] A. H. J. Fleming, E. B. Colorio (nee Bauer), The Spectroscopy of the EM Field-a Predicted Photon

Chemistry, 3rd International Wkshp on Biological effects of EM Fields, Kos, Greece, October 2004.

[6] L.B. Okun, Photon 2005, Warsaw, 2005.

[7] L. Pauling, The Nature of the Chemical Bond. New York, Cornell Univ Press, 1960.

[8] C. Caso et al. Particle Data Group, European Physical Journal C3, 1, 1998.

[9] R. Van Wilk,. Bio-photons and bio-communication, Journal of Scientific Exploration, vol 15, 2,.2001.


Chapter 1

Electromagnetic Field and Environment

Supervision of State System of Protection against 0 Hz – 300 GHz Electromagnetic

Fields Exposure in Poland

Halina ANIOŁCZYK1 Nofer Institute of Occupational Medicine, Lodz, Poland

Abstract. For 35 years already, a system for monitoring EMF exposure has been in operation in Poland. The system has been focussed primarily on the assessment of occupational exposure of the workers in plants and institutions using EMF-producing equipments, systems or installations, referred to as EMF sources. The system for monitoring of occupational EMF exposure is associated with human environmental protection. This paper presents the principles for the state system of protection against EMF and the project of the preparatory steps to be undertaken in association with Poland’s accession to the European Union.

Keywords. electromagnetic field, system of monitoring exposure

1. Introduction

In Poland, in 1970’s, State System of Monitoring Electromagnetic Field Sources was established, later on it has been renamed to State System of Monitoring Exposures to Electromagnetic Fields (EMF). Within the System, the State Sanitary Inspection (SSI) is responsible for the protection of the workers, while the problems of the protection of the general population from the environmental EMF are run by the Environmental Protection Inspection. Central Register of EMF Sources used for sanitary purposes, which continues to be updated each year, constitutes an element of the System. After Poland has accessed the European Union, it is necessary that the principles and regulations of the existing system be adjusted to the EU relevant regulations. The main legal regulations issued by the Euro Parliament and the EU Council include Directives, which are obligatory, and Recommendations, which are not obligatory. A Project has been prepared in Poland, intended to reinforcement the control over the State System of Monitoring Exposures to Electromagnetic Fields by implementing the EU methodology and practices. The Project has been accepted by the EU Commission and is being implemented since 2007 in collaboration with the Italian partner. The beneficiaries of the Transition Facility 2005 Twinning Contract PL2005/IB/SO/01 “Strengthening of State supervision and monitoring system of exposure to electromagnetic fields” include: Polish Ministry of Health, Chief Sanitary Inspector and the Nofer Institute of Occupational Medicine (NIOM), Lodz, Poland. The collaborating partners include the Italian Ministry of Health, Regional Agency for Environmental Protection of Toscany

1 Nofer Institute of Occupational Medicine, 91-348 Lodz, Teresy Street 8, Poland, E-mail:

[email protected]


27

(ARPAT) and the Agency of the Italian Public Administration Department of the Prime Minister’s Office (FORMEZ).

2. Legal Background

The underlying legal regulations for the State System of Protection against EMF are of various ranks, of which the highest is the Constitution; the regulations include acts of parliament, e.g. labour code, and some minor regulations on labour health protection.

Currently in Poland the questions of the protection of health of workers operating EMF-producing devices are regulated by the Labour Code and the associated executory provisions, such as:

−−−− Regulation of the Minister of Labour and Social Policy of 29 Nov. 2002 on the highest admissible concentrations and intensities of harmful agents at workplace [1];

−−−− Regulation of the Minister of Health of 20 April 2005 on testing and measuring of harmful agents at workplace [2].

The matters of the protection of the general population from EMF are regulated by the Law on Environmental Protection [3] and the executory provisions thereto, such as e.g. the Regulation of 30 Oct. 2003 by the Minister of the Environment on the admissible environmental EMF levels and methods to ensure that the levels are not exceeded [4].

In EU, the legal background for safety and health of workers includes directives based on Item 118A of the EU Treaty. The directives represent minimum standards, i.e. they do not infringe on the more stringent national regulations. The directives on labour health and safety referring to risks from physical agents, such as e.g. EMF, include:

−−−− Council Directive 89/391/EEC of 12th June 1989 on the introduction of measure to encourage improvements in the safety and health of workers at work [5].

−−−− Directive 2004/40/EC of the European Parliament and of the Council of 29th April 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields) (18th individual directive within the meaning of Article 16(1) of Directive 89/391/EEC) [6].

To protect the general population from EMF, the EU Commission suggests the use of:

−−−− Council recommendation 1999/519/EC of 12th July 1999 on the limitation of exposure of the general public to 0 Hz ¸ 300 GHz electromagnetic fields [7].

3. Aims

The major aims of the State System of Monitoring Exposures to Electromagnetic Fields currently operated in Poland include:

• sure correctly structured monitoring of environmental and occupational EMF exposures.

• Collect, on the nation-wide level, the information on EMF-emitting devices, installations and systems, and EMF exposure levels (computer-aided Data Base).

H. Aniołczyk / Supervision of State System of Protection Against 0 Hz – 300 GHz EMF Exposure28

• Eliminate and reduce unnecessary and excessive exposures to EMF in a competent, comprehensive, and correct manner.

• Ensure expert advice and information exchange to the personnel of research institutions and control laboratories by organising, on a regular basis, workshops, training courses and scientific conferences on modern measurement techniques with a view to limit EMF exposures and to extend personnel’s knowledge on the health effects of EMF exposures to humans and EMF environmental effects.

4. Organisations and Institutions Responsible for the Development and

Management

Solutions adopted in Poland are based on offices, institutions, and other state organisations, the statute of which includes the above mentioned tasks, such as the State Sanitary Inspection, the State Labour Inspection, and the Environmental Protection Inspection.

• Activities associated with health protection are supervised by the State Sanitary Inspection (SSI) through the network of its 16 regional Sanitary Epidemiological Stations (SES) and their agencies located in industry-intense regions. SSI is managed by the Chief Sanitary Inspector (CSI). Institutions operating EMF-emitting devices are supervised by SES personnel that, in addition to commercial accredited control and measurement laboratories, performs measurements of EMF exposures at workplaces. Those SSI activities constitute the basis for running the Data Base on EMF Sources. The collected data is used to prepare the Annual Report on Protection against 0 Hz-300 GHz EMF in the Occupational Environment.

• Authorised by the Chief Sanitary Inspector, the Nofer Institute of Occupational Medicine (NIOM), Lodz, Poland, runs a register of EMF sources, known as the Central Register of Electromagnetic Field Emitting Sources for Sanitary Purposes, which is updated each year. The Central Register quoted above is compiled from the Regional Registers that contain: a list of plants using EMF-emitting devices; the number of EMF sources classified according to the category of plant’s economic activity; number of people exposed to EMF arranged according to EMF exposure indices. The Central and Regional Data Bases on EMF Sources constitute a major component in the structure of EMF Sources Control System in Poland.

• The supervision and monitoring of working conditions, and in particular of compliance to the labour health and safety rules, is exercised by the State Labour Inspection through its network of 16 Regional State Labour Inspectorates (SLI).

• Chief Inspector of Environmental Protection is obliged to supervise the compliance with the regulations on the environmental protection and monitor the condition of the environment, and in particular: −−−− organise and coordinate state’s environmental monitoring, −−−− develop and implement methods to monitor and measure the environmental

characteristics.

H. Aniołczyk / Supervision of State System of Protection Against 0 Hz – 300 GHz EMF Exposure 29

Governmental and self-governmental organs running registers and lists, performing determinations and observations, and preparing analyses on the conditions of the environment are obliged to make the environmental data available, free of charge, for the purpose of environmental monitoring. To that end, 16 regional environmental protection inspectorates have been established.

5. Twinning Project on the Collaboration for the Transition Facility

and Adjusting the State Rules to the European Union Directives

According to the 2002 data collected by the NIOM Lodz, over 60 thousand EMF-emitting devices have been recorded in Poland, of which 63% were those used in radio communication, 21% in the industry, 15% in heath services and ca. 1% in the science. Over 45 thousand workers are users of those devices.

January/February 2007 saw the beginning of the implementation of the Contracting Authority Transition Facility 2005, Twinning Contract PL2005/IB/SO/01 on Strengthening of State Supervision and Monitoring System of Exposure to Electromagnetic Fields. The project is intended to:

−−−− Ensure implementation in Poland of the EU methods and practices for assessment of the risk of worker and general population exposure to EMF through adjusting Polish legal regulations to the EU law in the sphere of the protection of labour and general population exposed to 0 Hz - 300 GHz EMF.

−−−− Enhance the supervision over the existing State System of Monitoring Exposures to Electromagnetic Fields through increasing the competence of the personnel responsible for that controlling by personnel’s participation in training courses and workshops.

As part of an investment contract, modern equipment for EMF measurements shall be acquired for SES and NIOM. A service contract provides for modernisation, and adjusting to EU directives, of the annually updated Central Register of EMF Sources Used for Sanitary Purposes that serves as a tool for the assessment and management of occupational risk, including occupational exposure to EMF. As a result of modernisation of the existing software used to run the Data Base on EMF Sources, the latter shall be renamed to State Information System for Recording and Monitoring EMF Sources and EMF-Exposed Workers, and for Classification of that Exposure.

The Resident Twinning Advisers (RTA) and other expert aid is necessary to ensure that the Project objectives are duly achieved. The RTA reside in Poland throughout the duration of the Project as he is responsible for supervision and co – ordination of the Project’s implementation. Short- and long-time experts from various fields, such as organisation and management, measurement techniques, epidemiology, computer sciences, as well as experts in effects of EMF exposure, help in the implementation of the Project.

The implementation of the Project shall result in preparing the background for the incorporation of Directive 2004/40/EC into the national regulations and into the system of EMF control through:

• preparation of Procedure Book for the operation of the State Supervision System according to the requirements of the respective EU directives,

• training of expert personnel to run the State System of Monitoring Exposures to Electromagnetic Fields,

H. Aniołczyk / Supervision of State System of Protection Against 0 Hz – 300 GHz EMF Exposure30

• preparation of a Report on the ways of adjusting EU Directive requirements to the System, decisions by: −−−− Minister of Health, −−−− Minister of Labour, −−−− Minister of Environmental Protection.

References

[1] Regulation of the Minister of Labour and Social Policy of 29th Nov. 2002 on the maximum admissible concentrations and intensities of agents harmful to human health at workplaces. Annex 2. Part E. Journal of Laws. 217.1833 (2002, in Polish).

[2] Regulation of the Minister of Health of 20th April 2005 on the determinations and measurements of agents harmful to human health at workplaces. Journal of Laws. 73.645 (2005, in Polish).

[3] Act of 27th July – Environmental Protection Law. Journal of Laws. 62.627 as amended later on (2001,

in Polish). [4] Regulation of the Minister of Environment of 30th October 2003 on the maximum admissible

environmental EMF intensities and methods to verify that the intensities are not exceeded, Journal of Laws. 73.645 (2003, in Polish).

[5] 89/391/EEC, Council Directive 89/391/EEC of 12th June 1989 on the introduction of measure to encourage improvements in the safety and health of workers at work. OJ L 183, (29.6.1989), 1.

[6] 2004/40/EC, Directive of the European Parliament and of the Council of 29th April 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields) (18th individual directive within the meaning of Article 16(1) of Directive 89/391/EEC). OJ L 159, (30.4.2004), 1.

[7] Council recommendation 1999/519/EC of 12th July 1999 on the limitation of exposure of the general public to electromagnetic fields (0 Hz to 300 GHz), OJ L 199, (30.7.1999), 39.

[8] Notification of the Twinning Project Partners, Twinning contract PL 2005/IB/SO/01 Strengthening of State supervision and monitoring system of exposure to electromagnetic fields, Office of the Committee for European Integration. Undersecretary of State Tadeusz Kozek. Sekr.Min.TK/7410/159.1/0130/2007/DPR-WG. Warsaw, (11.01.2007).

H. Aniołczyk / Supervision of State System of Protection Against 0 Hz – 300 GHz EMF Exposure 31

Electromagnetic Interaction and Ergonomic Aspect Related to Operation of Computer

Monitors

Karol BEDNAREK Institute of Electrical Engineering and Electronics, Poznan University of Technology,

Poland

Abstract. The paper deals with environmental interaction of electromagnetic fields emitted by computer monitors. Moreover, an ergonomic problem is considered that is related to the work of computer users and interaction of the network frequency magnetic field with screen monitors. The paper also provides opinions on the results of calculation and measurements of electromagnetic fields caused by computer monitors.

Keywords. Electromagnetic interaction, computer monitors, electromagnetic fields, normative condition, calculation and measurements

Introduction

Computer is a device that is used nearly everywhere in social and economic life (the existential and work environment). Large numbers of people spend several or even dozens hours a day in front of computer monitors. Therefore, the care for securing proper working conditions of the computer users becomes very important. The interest in the problem is justifiable, taking into account the concern for human health and comfort, and considering the definite legal consequences resulting from employing the people working in “harmful labour conditions”.

Electromagnetic field (EMF) emitted by computer central units give no rise to human health hazard. The main attention should be paid to identification of EMF emitted by screen monitors and to ergonomics of operation of this equipment.

The paper makes reference to the state of standardization with regard to electromagnetic field emitted by the CRT computer monitors. Measurement results of electric and magnetic fields generated in the proximity of the monitors are presented. Moreover, the ergonomic aspect of interaction of the 50 Hz frequency magnetic field on the monitors is considered. The results are shown that have been obtained from calculation and laboratory measurements carried out in the premises of production plants subject to interaction of magnetic fields generated by power busways and its effect on operation of monitors. ____________________________________

Karol Bednarek: Institute of Electrical Engineering and Electronics, Poznan University of Technology, Piotrowo 3a, 60-965 Poznan, Poland; E-mail: [email protected]



32

1. Influence of Electromagnetic Field Emitted by Computer Monitors on Humans

1.1. Emission Sources and the Normative Condition

Main EMF sources of screen monitors are [1,2,3,4]: • the image tube (giving rise to the field of the highest frequency – ionizing and

optical radiation and electrostatic field), • brightness modulation system of the spot luminance (the fields of large

frequencies 105÷108 Hz),

• horizontal and vertical deflection systems – mainly deflector coils (the fields of low and extremely low frequencies),

• high voltage feeder (the electrostatic field). Large numbers of research studies and measurements carried out in various

research centres in the world show that in the range of high frequencies (inclusive of the ionizing radiation) the monitor-generated EMF-s are very weak or intensively damped. In consequence, their effect on human body is decidedly below allowable level [2,3,4].

The highest EMF-interaction of monitors occurs in case of very low frequencies (VLF) – in the range 2÷400 kHz, extremely low frequencies (ELF) – i.e. below 2 kHz, and electrostatic field. Therefore, further analysis is performed for such a radiation. Taking into account the wavelengths of the considered fields (the proximate zone) the magnetic and electric fields are analyzed separately.

Requirements of the Council of the European Union related to EMF exposition in the range 0÷300 GHz (according to the ICNIRP guidelines) have been published in July 30, 1999, in the Official Journal of the European Communities No L199/59. They provide the limits for a general population and a working environment subject to EMF in result of their professional occupation. On May 24, 2005, the Directive 2004/40/EC of the European Parliament and of the Council of 29 April 2004 has been published, related to the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields) (18th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC). According to the resolutions of the Directive three ways of assessment of exposition conditions of the workers are allowed: the estimation, measurement, and calculation of the values of electromagnetic field affecting the workers [5,6,7,8].

The legal acts binding in Poland with regard to protection against electromagnetic non-ionizing radiation are the regulations of ministers published in the Journal of Laws: with regard to the working environment – the Journal of Laws: Dz.U. No 217, pos.1833, 18.12.2002, and for a general population (the residential environment) – the Journal of Laws: Dz.U. No 192, pos.1883, 14.11.2003 [3,5,6,9,10].

Standardization with regard to EMF interaction in the proximity of computer monitors was carried out by the Swedish National Board for Measurement and Testing (SWEDAC), by publication of a set of the MPR Standards. The most severe limitations related to the matter are formulated in the requirements of the Swedish Confederation of Professional Employees TCO (several editions of the recommendations). Monitor manufacturers predominating on the market make efforts to meet the MPR and TCO requirements [2,4].

K. Bednarek / Electromagnetic Interaction and Ergonomic Aspect 33

1.2. Measurement of Slowly-Varying EMF in the Proximity of Screen Monitors

Magnetic and electric fields have been measured around the screen monitors in the ELF and VLF bands. The measurement has been performed with the use of the 3D H/E Fieldmeter ESM-100. Magnetic flux density B and electric field intensity E have been measured in definite distances from computer monitor (from the front). The measurements have been performed for the VOBIS Highscreen MS17S monitor. The results are shown in Figures 1 and 2.

0

200

400

600

800

1000

1200

1400

30 50 100 150 200 250 300 350 400 450 500

l [ mm ]

B [

nT

]

ELF

VLF

Figure 1. Dependence of magnetic flux density B [nT] expressed as a function of the distance l [mm] from the VOBIS MS17S monitor, for the ELF and VLF frequency bands

0

10

20

30

40

50

60

30 50 100 150 200 250 300 350 400 450 500

l [ mm ]

E [

V/m

]

ELF

VLF

Figure 2. Dependence of electric field intensity E [V/m] expressed as a function of the distance l [mm] from the VOBIS MS17S monitor, for the ELF and VLF frequency bands

Similar measurements have been made for the NEC – MultiSync V520, NEC – MultiSync FE770, and Philips 104B monitors. Results of the tests are presented in [3,4,5]. The measurement results obtained for the magnetic and electric fields are of similar range to the case of the Vobis monitor. In case of older monitor versions the levels of interacting fields are slightly higher than in more modern ones (this particularly concerns the ELF frequency of electric field), nevertheless, they meet the normative requirements (in accordance with the year of their manufacture).

K. Bednarek / Electromagnetic Interaction and Ergonomic Aspect34

2. Ergonomic Aspect of the Effect of the Disturbances Caused by Magnetic Field

of 50 Hz Frequency on Computer Monitors

Any requirements related to electromagnetic compatibility of computer monitors with regard to their emissivity and immunity are fulfilled at the stage of their manufacture (this is confirmed by the CE mark assigned to the devices). A specific negative effect is exerted on operation of the CRT monitors (not provided by the standards) by magnetic field of power network frequency. This is an oscillation approximating the image repetition frequency (50÷120 Hz). In the case of relatively small interaction of the magnetic field (of the induction level reaching several μT) the monitor image vibrates with the differential frequency that is burdensome for the user (the disturbances of the work ergonomics) [3,4,5].

Such condition may arise in the cases of computers located in the proximity of heavy current power supply (heavy-current busways, power cables, etc.). In order to present the scale of the problem an identification of the magnetic field in the neighbourhood of a heavy-current line (i.e. power busway) has been carried out. Results of calculation of magnetic flux density around a busway operating in plane system are shown in Figure 3. In bottom part of Figure 3 a scale is shown that presents the values of magnetic flux density B [T], depicted by particular colours (in greyscale). The laboratory measurements have been performed in a similar system, the results of which are presented in Figure 4 and Figure 5.

Figure 3. Distribution of magnetic flux density B [T] in the proximity of phase conductors of a heavy-current line operating in plane system

As a final practical verification of the considered interactions the values of magnetic flux density have been measured at the area of a plant, where computer stands were arranged above a transformer station supplying power to the production bay by means of a cable suspended under the ceiling (being a floor of the office rooms above). The magnetic flux density at the computer stand desktop located directly above the busway amounted to 8 μT. The computer monitor image was subject to important oscillation, precluding normal operation of the stand.


0

0,2

0,4

0,6

0,8

1

1,2

1,4

50 100 150 250 300 400 600 700

d [mm]

B [mT]

Bp [mT]

Bw [mT]

B [mT]

Figure 4. RMS value of magnetic flux density B [mT], cross component of the magnetic flux density Bp [mT], and longitudinal component of the magnetic flux density Bw [mT] as functions of the distance d [mm] from the busway

0

0,04

0,08

0,12

0,16

0,2

300 400 500 600 700 800 1000 1200 1500 2000

d [mm]

B [mT]

Figure 5. Dependence of magnetic flux density B [mT] expressed as a function of the distance d [mm] from the busway (for greater distances)

Similar effects have been recorded in case of computers located at a laboratory station of technical inspection of electric power meters and in a control-room of a thermal-electric power station (where computer equipment was located on the desks placed several meters from power busways). Magnetic fields of the range from several to dozen μT arising in such locations resulted in disturbance of operation of CRT monitors manifesting themselves in onerous monitor image oscillation. The intensive oscillation led to increasing fatigue of the computer users and, in some cases, entirely precluded the work [3,4,5].

K. Bednarek / Electromagnetic Interaction and Ergonomic Aspect36

3. Final Notes and Conclusions

The magnetic and electric fields generated by screen monitors in the ELF and VLF frequency bands are relatively large as compared to the radiation of the fields of higher frequencies. Anyway, their values are below the allowable levels provided by appropriate legal provisions. Sometimes, the values approximate limit levels referred to by the Swedish MPR and TCO standards and recommendations, considered to be world-wide patterns.

The screen monitors are susceptible to influence of an external magnetic field of power network frequency. The field of magnetic flux density reaching 1 μT may cause image oscillations that are burdensome for the user (the disturbances of the work ergonomics). Such conditions may arise in case of location of the computer stands in the proximity of heavy-current equipment, i.e. power busways or cables (high power supply), resistance and induction furnaces, production bays or laboratory stands supplied with heavy currents, etc. Disadvantageous electromagnetic interaction with computer monitors may be eliminated or at least reduced by means of proper screens. In some cases even minor changes in computer stand location may be sufficient (as the magnetic field distribution strongly depends on the distance from its source).

References

[1] Z. Garbarczyk, C. Kozłowski, M. Nowicki, K. Pachocki, Electromagnetic hazards, from the series entitled: Human Safety and Protection in the Working Environment, Part 11, Central Institute for Labour Protection, 1998. (In Polish).

[2] A collective elaboration edited by J. Bugajska: Computer workplace. Health and ergonomics aspects, Central Institute for Labour Protection, Warsaw 1999. (In Polish).

[3] A collective elaboration edited by A. Krawczyk: Bioelectromagnetism, The Research-Scientific Institute ZTUREK, Warsaw, June 2002. (In Polish).

[4] K. Bednarek, The problems of slowly-varying magnetic and electric fields in computer monitors – the question of emissivity and immunity, Academic Journals, Electrical engineering, No 50, Poznan Uniwersity of Technology, Poznań 2006, s. 129-137. (In Polish).

[5] K. Bednarek, Electromagnetic influence of heavy-current busways, Electrotechnical Review No 12, 2003, s. 897-899. (In Polish).

[6] J. Karpowicz, M Hietanen, K. Gryz, EU Directive, ICNIRP guidelines and Polish legislation on electromagnetic fields, International Journal of Occupational Safety and Ergonomics (JOSE), Vol. 12, No. 2, pp. 125-136, 2006.

[7] Directive 2004/40/EC of the European Parliament and of the Council of 29 April 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields) (18th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC). Official Journal of the European Union (L 159, 30.04.2004) L 184, 24.05.2004.

[8] Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300 GHz), Health Physics, vol. 74, no 4, pp. 494-522, April 1998.

[9] Regulation of the Minister of Labour and Social Policy of 29 November 2002 on the maximum admissible concentrations and intensities for agents harmful to health in the working environment, Dz.U. No 217, item 1833, 18.12.2002. (In Polish).

[10] Regulation of the Minister of Environment of 30 October 2003 on maximum admissible levels of electromagnetic fields in the environment and methods of checking adherence to these levels, Dz.U. No 192, item 1883, 14.11.2003. (In Polish).


Magnetic Field around Asynchronous Electrical Machines with Variable

Frequency Felipe DÍAZ1, Fabián DÉNIZ, Guillermo HERNÁNDEZ

Electrical Engineering Department. University of Las Palmas de Gran Canaria

Abstract. The aim of this paper is the essay and measurement of the magnetic induction at low frequencies produced by an asynchronous electrical machine. Measurements have been taken near to the machine, starting from its axis. We have worked at different frequencies, all of them below 50 Hz. This way we have studied the relationship between a non-punctual source of magnetic field, the frequency of the voltage and the values of the M.F. around it.

Keywords. Magnetic Field, Electrical Machines, Human Environment

1. Instrumentation and Equipment

Due to its relevance, magnetic fields in the air gap of electrical machines have been broadly studied. The design, calculus and construction of rotating machines depend upon the values of the magnetic induction between stator and rotor.

However magnetic fields are too, the centre of a controversy because of its possible influence over human and animal health. From this point of view, it is necessary to analyse the production and presence of magnetic fields in the usual human environment.

As part of a more ambitious project to characterize the magnetic field around big asynchronous machines, we have started essaying a machine with different frequencies, all of them below 50 Hz. The aim of the work is to describe how the magnetic field varies with some other electrical and mechanical variables. The first parameters under study were the distance to the machine and the frequency of the supply voltage, what definitely implies the frequency of the magnetic field in the air gap. We have measured the magnetic field around the machine taking as reference the machine long axis.

A 75 kW asynchronous machine with Ward Leonard has been essayed. It has a speed control system using a frequency converter. The frequency converter is an Omron Sysdive 400 V. In Figure 1 you can see the essayed electrical machine. The asynchronous machines controlled by frequency converters are quite common in nowadays industry, so this is a typical example of an industrial worker environment.

The magnetic fields measurements are expensive. Any equipment with minimum quality requirements is a high cost one. Due to the social interest in this matter, the group of the Electric Department could purchase an equipment to measure electric and

1 Electrical Engineering Department. University of Las Palmas de Gran Canaria, Edif. de Ingenierías.

Campus de Tafira. Las Palmas 35017. SPAIN; E-mail: [email protected]



38

magnetic fields around lines, transformers and substations. The equipment we used is a portable magnetic field measurer, PMM 8053A. The probes are absolutely independent from the measurement equipment, so we can apply all the distance requirements to measure fulfilling all the restrictions that are necessary to have taken into account.

Figure 1. Asynchronous machine essayed with measurement probe

2. Methodology and Results

The machine has been started at a low frequency of 5 Hz and, with the machine spinning in stationary state, the magnetic induction has been measured placing the probe under the machine and by its axis. After that, measurements have been taken in different places moving the probe further away from the machine axis. For each and every essay, the operator was far enough to not taking into account the increase of uncertainty due to this cause.

This procedure has been repeated changing the frequency of the three phase supply in order to watch the behaviour of the magnetic field around the machine, with different frequencies.

Figure 2 shows the two-dimensional geometrical distribution of the magnetic field around the electric machine for different frequencies, starting with 5 Hz up to 30 Hz using 5 Hz wide intervals. These low frequencies show higher values what means a worse behavior from the workers health perspective. Anyway, all the measurements taken have values under 30 μT under the machine, reaching values around 12 μT for a frequency of 30 Hz.

F. Díaz et al. / Magnetic Field Around Asynchronous Electrical Machines 39

0,00

5,00

10,00

15,00

20,00

25,00

30,00

Indu

ctio

n ( μμ μμ

T)

Distance (cm)

Magnetic Field Distribution

5 Hz

10 Hz

15 Hz

20 Hz

25 Hz

30 Hz

Figure 2. Magnetic field versus distance to machine axis and frequency

Also, it is interesting to analyze the variation of the magnetic field in one

geometric point, with the frequency. Figure 3 shows the variation of the induction in the axis versus frequency.

B = -0.6854f + B0

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

0,00 5,00 10,00 15,00 20,00 25,00 30,00 35,00

Indu

ctio

n (m

T)

Frequency (Hz)

B=F(f)

Experimental

Trend

Figure 3. Magnetic field in the machine axis versus frequency

A simplified expression can be deduced for this case. It is shown in Eq. (1).

B = -0,685 f +B0 (1)

If we study different distances, we can generalize and write Eq. (2).

F. Díaz et al. / Magnetic Field Around Asynchronous Electrical Machines40

Bd(d) = m f +B0d(d) (2)

Where m is a parameter which depends exponentially on the distance to the source. It is shown in Figure 4.

m = -0,685 e –0,035d (3)

The induction, therefore, would be as shown in Eq. (4).

Bd(d) = -0,685 f e –0,035d + B0d(d) (4)

Where the first addend is the value of the decrease of the magnetic field from the reference value B0d. Watch the fact that in this addend, the value affected by the exponential decrease, increases with the frequency as it is represented in the figures. Please take note that B0d is not a constant, but a function that depends on the distance to the machine axis.

-0,8-0,7-0,6-0,5-0,4-0,3-0,2-0,1

0

0 20 40 60 80 100 120 140 160 180 200Axis distance (cm) Parameter m

Experimental Trendm = -0.6854e-0.0352d

Figure 4. Parameter m evolution

3. Conclusions

The magnetic field induction has been measured around a three phase asynchronous electrical machine controlled through a frequency converter. This is the first step to make a more complex and complete characterization of the magnetic field in an industrial environment.

The essay has taken into account different points around the machine, and different frequencies for the electrical supply. The dependence of the magnetic field with the distance is a well known relationship.

To study the influence of the voltage and current frequency, a simplified expression of the induction depending on frequency has been obtained. A parameter (m) which links distance to source and frequency has been defined. Its evolution is exponential.

F. Díaz et al. / Magnetic Field Around Asynchronous Electrical Machines 41

References

[1] J. D. Bowman, M. A. Kelsh, W. T. Kaune, Manual for Measuring Occupational Electric and Magnetic Fields Exposure, NIOSH, 1998, Cincinnati.

[2] ANSI/IEEE Std 644-1987, IEEE Standard Procedures for Measurement of Power Frequency Electric and Magnetic Fields from AC Power Lines, Institute of Electrical and Electronics Engineers, 1987, New York, USA.

[3] M. Borsero, G. Crotti, L. Anglesio and G. d’Amore, Calibration and Evaluation of Uncertainty in the Measurement of Environmental Electromagnetic Fields, Radiation Protection Dosimetry, Vol. 97, No 4, pp. 363–368, 2001, Nuclear Technology Publishing.

F. Díaz et al. / Magnetic Field Around Asynchronous Electrical Machines42

Measurement of Electromagnetic Fields in

the Vicinity of 66kV/20kV Substation

Power (Gran Canaria Island, Spain)

Fabián DÉNIZ 1

, Felipe DÍAZ, Antonio PULIDO and Miguel MARTÍNEZ

Electrical Engineering Department. University of Las Palmas de Gran Canaria

Abstract. In this paper, the extremely low frequency (ELF) electromagnetic field

environment around 66kV/20kV substation power is studied. This substation is

located in Gran Canaria island, more precisely in a municipality with the largest

tourist area on the island, covering one fifth of its surface. The relevance of these

measurements is great because there are multi-family dwellings around the

substation. These measurements were made using Digital Signal Processing (DSP)

techniques. Also, several existing overhead transmission lines are in an area that

has seen significant residential growth

Keywords. magnetic field, human environment

Introduction

The last years has witnessed growing public concern over possible adverse health effect

of electromagnetic fields produced by transmission and utilization of electric power.

The population growth needs land for building development what causes an

expansion of the urban centre. This expansion can move nearer electrical

infrastructures that were isolated initially from any area of dwellings. The present work

is born due to a group of residents whose homes are near a transformer substation of

66kV/20kV

The potential hazard due to exposure to extremely low frequency (ELF)

electromagnetic fields emitted by electric power systems and installations has become a

major public and environmental concern.

1. Substation Characteristics

First of all, the power electric network of the Gran Canaria Island is shown in Figure 1.

There are twenty substation power and electric and magnetic fields in one of them were

measured.

1

Electrical Engineering Department. University of Las Palmas de Gran Canaria, Edif. de Ingenierías.

Campus de Tafira. Las Palmas 35017. SPAIN; E-mail: [email protected]


43

Figure 1. Power electric network of Gran Canaria Island

In order to investigate the magnetic field environment accurately, we carried out

measurements magnetic field distribution in the 66kV/20kV substation.

The main characteristics are: overhead transmission lines of 66 kV, underground

cables of 20 kV and three power transformers. The substation has three power

transformers, two of them of 30 MVA and one of 40 MVA. Also there is double-circuit

configuration. The substation is connected with the power transmission lines passing

near the substation. The Figure 2 shows the single-line diagram of 66 kV.

Figure 2. Single-line diagram of 66 kV

F. Déniz et al. / Measurement of EMF in the Vicinity of 66kV/20kV Substation Power44

The secondary cables with 20kV located at about 1 meter under ground and the

single-line diagram of 20 kV is shown in Figure 3.

Figure 3. Single-line diagram of 20 kV

Results

Before showing the results it is advisable to remember which are the reference levels

for general public exposure to time-varying electric and magnetic fields (to the

frequency of 50 Hz):

− 5.000 V/m electric field

− 100 µT magnetic field

The magnetic field values around substation were represented in Figure 4. The

maximum value obtained of magnetic field was 2,2 µT.

Magnetic Field (µT)

0,00

0,50

1,00

1,50

2,00

2 4 6 8 10 12 14 16 18 20 22

# item

Ma

gn

etic

F

ie

ld

(µ

T)

Figure 4. Magnetic field

F. Déniz et al. / Measurement of EMF in the Vicinity of 66kV/20kV Substation Power 45

Likewise, electric field values were represented in Figure 5, being maximum value

of electric field was 41,10 V/m

Electric Field (V/m)

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

40,00

45,00

23 24 25 26 27 28 29 30 31 32

# item

Ele

ctric

F

ie

ld

(V

/m

)

Figure 5. Electric field

2. Conclusions

In this studied area, overhead transmission lines don’t cause levels exposure to time-

varying electric and magnetic fields upper legally allowed levels.

Maximum level of magnetic field was obtained over underground cable of 20 kV,

near urban population. Measured magnetic field strength is agreed applicable legal

rules in Spain.

These measurement data may be a useful technique predicting ELF magnetic field

environment around the power transmission / substation systems.

References

[1] International Commission On Non-Ionizing Radiation Protection (ICNIRP), Exposure to Static and

Low Frequency Electromagnetic Fields, Biological Effects and Health Consequences

(0- 100 kHz), ICNIRP 13/2003.

[2] Cigre Technical Brochure 221, Improving the impact of existing substations on the environment, Paris

[3] Earle C. Bascom et al, Magnetic Field Management Considerations for Underground Cable Duct

Bank.2005 IEEE Transmission & Distribution Conference –9-14 October 2005. Paper . 05TD0399.

New Orleans, Louisiana.

[4] K. Kato, Y. Uga, N. Goto, M. Shimizu, H. Okubo, Magnetic field characterization based on line current

conditions in 77kV/6.6kV substation, High Voltage Engineering Symposium, 22-27 August 1999

Conference Publication No. 467.0 IEE. 1999.

[5] I. A. Metwally, W. J. Zischank, F. H. Heidler, Measurement of Magnetic Fields Inside Single- and

Double-Layer Reinforced Concrete Buildings During Simulated Lightning Currents, IEEE transactions

on electromagnetic compatibility, vol. 46, no. 2, May 2004.

[6] IEEE Magnetic Fields Task Force, A protocol for spot measurements of residential power frequency

magnetic fields, IEEE Trans. PWRD, Vol.8, No.3, pp. 1386-1394, July 1993.

[7] IEEE Power Engineering Society, IEEE Standard 644-1994 Procedures for measurement of power

frequency electric and magnetic fields from AC power lines, New York, March 1995.

[8] A V. Mamisheve, B. D. Russell, Measurement of Magnetic Field. in the Direct Proximity Power Line

Conductors, IEEE Trans. on Power Delivery, Vol. 10, No.3, July 1995, pp.1211-1216.

F. Déniz et al. / Measurement of EMF in the Vicinity of 66kV/20kV Substation Power46

Magnetic Field Exposure from Multiple

Overhead Transmission Line in Urban

Utilities Corridor

Mário L. PEREIRA FILHO1

, José Roberto CARDOSO (2)

(1)

Instituto de Pesquisas Tecnológicas de SP, Cidade Universitária

05508-901 São Paulo – SP – Brasil, [email protected]

(2)

Escola Politécnica da USP, Av. Prof. Luciano Gualberto, trav. 3, n. 158

Cidade Universitária, 05508-900 São Paulo - SP – Brasil, [email protected]

Abstract. Supplying electric power to central metropolitan areas is challenged by

free area to build overhead high voltage transmission lines (OHTL). A solution is

to share existing right-of-way (ROW). As a result, there are two or three voltage

levels OHTL and oil and gas underground pipes. This paper presents a method to

calculate magnetic field human exposure in the proximity of an utilities corridor

with 345 kV, 230 kV and 88 kV OHTL in Sao Paulo metropolitan region,

considering power flow direction and phase shift between concerned OHTL.

Keywords. ELF magnetic field; utilities corridor; human exposure; overhead high

voltage transmission lines.

Introduction

A previous paper presented a software tool CampoLT [1] to calculate ELF

electromagnetic field from TL on the environment. A pilot study was conducted around

an 88 kV double vertical circuit TL in Sao Paulo city to validate this software tool in an

urban scenario. Fig 1 shows measured versus calculated values, with a good agreement

results [2].

Figure. 1 shows results for only one TL configuration. Sao Paulo metropolitan region

has some utilities corridors sharing TL of 345 kV, 230 kV and 88 kV voltage levels. To

calculate magnetic field from this corridor is necessary to know, additionally to

geometry and electric current magnitude, direction of power flow and current phase

shift between TLs, associated with step-down delta-wye power transforms. Reichelt et

all [3] analyzed a double vertical circuit case. This present paper extends such analyze

to multiple TL.

Corresponding Author: Mário L. Pereira Filho Corresponding author: Instituto de Pesquisas Tecnológicas de

SP Cidade Universitária 05508-901 São Paulo – SP – Brasil, [email protected]


47

Figure 1. Calculated versus measured magnetic field

1. Results

Case 1 – Corridor with one 345 kV and one 88 kV TL

Calculation was done for a corridor with TL according Table 1. Figure 2 shows a

picture of the row-of-way. Phase sequence is low reactance type.

Table 1. TL technical data

Nominal

voltage

(kV)

Nominal

current

(A)

Lower

phase

height

(m)

Distance between

phase(m)

Distance between

circuits (m)

Typical load

factor (%)

345 2000 30 7.5 6 80

88 950 14 2.4 5 72

345 kV TL is part of the high voltage ring supply for Sao Paulo metropolitan area.

Direction of power flow depends on energy balance concerning Southeast , North and

Northeast Brazilian regions. Current phase shift is 30 degree lead for 345 kV TL. Both

TL are double vertical circuit configuration.

Fig. 3 shows magnetic field values in a direction perpendicular to the ROW, at 1.0m

height. Load conditions for 345 kV TL are 66% load factor, 60% nominal load for

circuit 1 and 40% nominal load for circuit 2. Load conditions for 88 kV TL according

legend of Fig. 2, 72 % load factor, 1 = equal direction of 345 kV power flow, -1 =

inverse direction, last number pairs are load combination in percent of nominal load.

M.L. Pereira Filho and J.R. Cardoso / Magnetic Field Exposure from Multiple Overhead TL48

Figure 2. Row-of-way with towers silhouette

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 5 10 15 20 25 30

Distance from ROW border (m)

Ma

gn

etic

fie

ld

(u

T, R

MS

)

72_ 1_100_ 0

72_ 1_ 0_100

72_ 1_ 50_ 50

72_ 1_ 40_ 60

72_ 1_ 60_ 40

72_ -1_100_ 0

72_ -1_ 0_100

72_ -1_ 50_ 50

72_ -1_ 40_ 60

72_ -1_ 60_ 40

345 kV88 kV

Figure 3. Magnetic field values for both equal and inverse power flow direction

M.L. Pereira Filho and J.R. Cardoso / Magnetic Field Exposure from Multiple Overhead TL 49

ROW width is 30 meters, with borders at 0 m and 30 m. Arrows show position of 345

kV and 88 kV TL axe. There is an important field value reduction when power flow is

reversed in 88 kV TL side. Such a reduction can be explored to mitigate magnetic

fields in the proximity of ROW.

Spot measurements executed around noon in a business day, on TL axes found 4.0 μT

and 4.7 μT for 345 kV and 88 kV, respectively. Actual load factor in the moment of

measurements are unknown. There is a fair agreement with the last figure, but the

former one suggests 345 kV TL operation condition are different from simulated data.

Case 2 – Corridor with two 230 kV and two 88 kV TL

Calculation was done for a corridor with TL according Table 2. Fig. 4 shows a picture

of the row-of-way. Phase sequence is low reactance type.

Table 2. TL technical data

Nominal

voltage (kV)

Nominal

current

(A)

Lower

phase

height (m)

Distance between

phase(m)

Distance between

circuits (m)

Typical load

factor (%)

230 (1) 814 13 6.5 12 80

230 (2) 814 13 6.5 12 80

88 (1) 780 9 2.4 2.6 72

88 (2) 2020 9 3.6 4.2 72

Figure 4. Row-of-way with towers silhouette


Figure 5 shows magnetic field values in a direction perpendicular to the ROW, at 1.0m

height. Load conditions for 230 kV TL are 100% load factor, 50% nominal load for

both circuit 1 and 2. Load conditions for 88 kV TL according legend of Figure 5, 66%

load factor for TL (1) and 72% load factor for TL (2), 1 = equal direction of 230 kV

power flow, -1 = inverse direction, last number pairs are load combination in percent of

nominal load.

0

2

4

6

8

10

12

14

16

18

0 10 20 30 40 50 60

Distance from left ROW border (m)

Ma

gn

etic

fie

ld

(u

T R

MS

)

72_ 1_100_ 0

72_ 1_ 0_100

72_ 1_ 50_ 50

72_ 1_ 40_ 60

72_ 1_ 60_ 40

72_ -1_100_ 0

72_ -1_ 0_100

72_ -1_ 50_ 50

72_ -1_ 40_ 60

72_ -1_ 60_ 40

230 kV(1)88 kV(2)88 kV(1)

230 kV(2)

Figure 5. Magnetic field values for both equal and inverse power flow direction

ROW width is 60 meters, with borders at 0 m and 60 m. Arrows show position of 230

kV and 88 kV TL axe. There is a noticeable field value reduction when power flow is

reversed in 88 kV(2) TL side.

3. Conclusion

The most relevant conclusion concerning human exposure on border of ROW is that

major contributions are from 88 kV TL. This is because there are higher currents and

lower clearance from ROW border on lowest voltage TL.

Inverse power flow mitigates magnetic field near the TL with inverse power flow.

However, for power companies, power flow is a consequence of generation / demand

scenario, it is not possible to choose an arbitrary power flow for mitigate magnetic

field.

References

[1] M. L. Pereira Filho, J. R. Cardoso., A Coupled 3D CSM – BEM software tool to evaluate ELF fields

near power lines. International Conference on Electromagnetic Fields, Health and Environment

– EHE2006. 27th – 29th April, 2006. Madera Island, Portugal.

M.L. Pereira Filho and J.R. Cardoso / Magnetic Field Exposure from Multiple Overhead TL 51

[2] M. L. Pereira Filho, J. R. Cardoso., Urban fields pilot project with TL LTA Sul Ban 1-2. EMF-SP II

Workshop, 14th – 15th August 2006, Sao Paulo - Brazil.

[3] Reichelt D., Scherer R., Braunlich R., Aschwanden T., Magnetic field reduction measures for

transmission lines considering power flow conditions. Transmission and Distribution Conference, 1996.

Proceedings 1996, p 486-492, IEEE.


Determining Health Risk of 154kV, 50Hz Power Transmission Line

Cihan GUNESER, Ozge SAHIN, Hacer SEKERCI OZTURA

Dokuz Eylul University, Department of Electrical and Electronic Engineering Buca, Izmir-TURKEY

Abstract. This study covers a case study on magnetic field measurements in a university campus area in Izmir, Turkey. A power transmission line of 154 kV, 50 Hz has previously been located inside of this area. In this study, it is aimed to determine the health risk of this transmission line in its vicinity. Measurements are realized using a calibrated Gauss-meter in multiple locations in different times. These measurements give people an idea about the safety of settling around power transmission lines. Safe distance limits are determined according to the international standards.

Keywords. Power transmission line, magnetic field, health, international standards

Introduction

In recent years, electromagnetic field and its effects on human health has become an important subject of researches. It is already known that ionising magnetic radiation is harmful for human. But non-ionising radiation is still not proved to be harmful with medical proof but statistical researches show that people who live near high voltage transmission lines have higher health risks. In this paper, an extremely low frequency measurement is made and the results are compared to limits that are determined by international standards.

Electromagnetic fields consist of electric (E) and magnetic (H) waves traveling together [1], as shown in Figure 1.

Figure 1. Electric and magnetic field


53

Frequency is an important parameter for electromagnetic fields. Table 1 shows the classification of frequency ranges where “S” means super, “U” means ultra, “V” means very, “L” means low, “M” means medium. ELF (Extremely Low Frequency) includes magnetic field of which frequency is between 3 Hz and 60 Hz. In this paper the frequency of interest is 50 Hz. This frequency is also used in transmission lines in most of the countries over the world.

Table 1. Frequency classes

ELF SLF ULF VLF LF MF HF VHF UHF SHF EHF

3 Hz 60 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz

60 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz 300 GHz

1. Transmission Line Properties and International Standards

Electric power transmission and distribution, a process in the delivery of electricity to consumers, is the transfer of electrical power and schematic of the system is shown in Figure 2.

Typically, power transmission is between the power plant and a substation near a populated area. Due to the large amount of power involved, transmission normally takes place at high voltage (110 kV or above). Electricity is usually transmitted over long distance through overhead power transmission lines which consist of non-isolated wires. Today, transmission-level voltages are usually considered to be 110 kV and above. Lower voltages such as 66 kV and 33 kV are usually considered sub-transmission voltages but are occasionally used on long lines with light loads. Voltages less than 33 kV are usually used for distribution [2, 3].

Figure 2. Schematic of electric power transmission and distribution system

C. Guneser et al. / Determining Health Risk of 154kV, 50Hz Power Transmission Line54

020406080

100120

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

Horizontal Distance

Mag

netic

Fie

ld (m

G)

Magnetic Field (mG) May 23rd Wed 15:00

Magnetic Field (mG) May 26th Sat 16:00

In this paper, transmission lines in Dokuz Eylul University Campus, Izmir are examined. Overhead electric power transmission line systems in Turkey are operated mainly at 154kV and 380kV. Majority of the transmission lines are double circuit and vertically arranged. Unfortunately, there is a high voltage transmission line in the campus area. Measurements are taken by using a calibrated digital EMF tester. Measurements were repeated increasing 5 meter-distances perpendicular to transmission lines. Two different groups of values are measured on different dates. One group is taken in midday, on Wednesday. The other group is taken at the weekend, on Saturday. The aim is to see the difference in magnetic field values between the working hours and vacation. It is also important to which area the transmission lines are transmitting electricity. The values may change depending on these factors. The material that is used for transmission is also important. The earth conductivity, actual current frequency is also important for calculation. Measured magnetic field values are shown in Figure 3 for 154 kV transmission lines.

Figure 3. Measurement results

2. Limit Values for EMF

EMF values must be in a limit, which is determined by WHO (World Health Organization) and the other international standards. After biological studies and according to recent reports, magnetic field should be less than 0,002 Gauss in the environment of man for a long time. Tables 2 and 3 show the required distance for different voltage values and different kinds of areas [3-6]. Table 2. Parameters of 110 kV high voltage transmission line

line passing area minimum distance from conductor

to ground d [m]

location of max. value of B at y=1,8 m

x [m]

maximum value of B at y=1,8 m

[Gauss]

area of B<0,002 Gauss

residential area 7,0 0,0 0,1139 x>49,0 m non-residential area 6,0 0,0 0,1548 x>49,5 m difficult traffic area 5,0 0,0 0,2179 x>49,5 m

C. Guneser et al. / Determining Health Risk of 154kV, 50Hz Power Transmission Line 55

Table 3. Parameters of 220 kV high voltage transmission line

line passing area minimum distance from conductor

to ground d [m]

location of max. value of B at y=1,8 m

x [m]

maximum value of B at y=1,8 m

[Gauss]

area of B<0,002 Gauss

residential area 7,5

0,0

0,0

0,1484

0,1211

x>77,5 m (horizontal erect)

x>64 m (triangle erect)

non-residential area 6,5

0,0

0,0

0,1805

0,1503



difficult traffic area 5,5

0,0

-3,0

0,2276

0,1972



3. ELF and Human Health

When standing below a high-voltage power line with a positive polarity, body would develop a negative charge. Electric field lines originate at the source and land on the body. As charge reverse so would body charges reverse. The person distorts field lines in from nearby space so they land perpendicular to the head. The electric field around the head becomes highly concentrated and intense. [7,8]

Most evident biological effects are cell membrane, tumor growth, circadian rhythms, stimulation of nerves and muscles and tissue heating. When a person is in electromagnetic field, calcium ions are moved from inside of a cell through the cell membrane to the outside.

Some investigators have reported that ELF field exposure may suppress secretion of melatonin, a hormone connected with our day-night rhythms. It has been suggested that melatonin might be protective against breast cancer so that such suppression might contribute to an increased incidence of breast cancer already initiated by other agents. While there is some evidence for melatonin effects in laboratory animals, volunteer studies have not confirmed such changes in human bodies [7].

There is no convincing evidence that exposure to ELF field causes direct damage to biological molecules, including DNA. It is thus unlikely that they could initiate the process of carcinogenesis. However, studies are still underway to determine if ELF exposure can influence cancer promotion or co-promotion. Recent animal studies have not found evidence that ELF field exposure affects cancer incidence.

Many studies published during the last decade on occupational exposure to ELF fields have exhibited a number of inconsistencies. They suggest there may be a small elevation in the risk of leukemia among electrical workers. However, confounding factors, such as possible exposures to chemicals in the work environment, have not been adequately taken into account in many of them. Assessment of ELF field exposure has not correlated well with the cancer risk among exposed subjects. Therefore, a cause-and-effect link between ELF field exposure and cancer has not been confirmed.

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has published guidelines on exposure limits for all EMF. The guidelines provide adequate protection against known health effects and those that can occur when

C. Guneser et al. / Determining Health Risk of 154kV, 50Hz Power Transmission Line56

touching charged objects in an external electric field. Limits of EMF exposure recommended in many countries are broadly similar to those of ICNIRP, which is a non-governmental organization (NGO), formally recognized by WHO and a full partner in the International EMF Project. It will reassess its guidelines once the EMF Project has completed new health risk assessments.

4. Conclusion

Electric and magnetic fields exist, because electricity is generated, transmitted, distributed and also used. So, questions related to the possible health effects from power frequency have increased recently. There are still many questions that need to be answered to determine hazards to human.

In this paper, EMF measurements are taken near 154 kV transmission lines. Measurement results are compared to other results of some other transmission lines. It is seen that, these results are similar to others. And the graphics of EMF values are parabolic. When calculation is made on the paper, same kind of a graphic will be determined.

It is tried out to find the EMF values near the transmission lines in our campus which are close to classrooms. For 154kV, nearest classroom or residential building has to be at least 70 meters far from lines. This distance has 2 mG EMF value which is determined by international standards. The aim was to see if residential buildings are in reasonable distance from lines. It is seen that these buildings are usually in border of reasonable distance. Generally, necessary attention is not paid for EMF and its effects on human health.

References

[1] http://www.who.int/peh-emf/en/ [2] GAO Yougang, Analysis of Magnetic Field Environment Near High Voltage Transmission Lines, 1998. [3] S. A. Mahmoud, M. A. Abdallah, H. I. Anis, Magnetic Fields around 2200-66kV Transmission Line,

IEE High Voltage Engineering Sym., 22-27 August 1999. [4] Perarnbur., Neelakanta, Vichate, Ungvichian; Electromagnetic Fields Due To Overhead and Buried

High-Voltage Power-Lines: A Quantitative Comparison, 1989. [5] J. F. Heneage, P. E. Ashley, J. R. Ashley; An EMF Mitigation Technology for Power Transmission

Lines, Ph.D. dissertation, 2004. [6] L.Li, G. Yougang, Analysis of Magnetic Field Enviroment Near High Voltage Transmission Lines,

IEEE Inter. Con. on Communication Technology, 22-24 October 1998, China. [7] G. Rauch, S. Sussman N. G. Hingorani, Electric and Magnetic Fields: Background on Health Effects

and an Update on Eprl Research, 2004. [8] G. Robert G. Olsen, Electromagnetic Fields from Power Lines, School of Electrical Engineering and

Computer Science, Washington State University, 2004.

C. Guneser et al. / Determining Health Risk of 154kV, 50Hz Power Transmission Line 57

Improvement of Electromagnetic

Compatibility an Electro-Energetic

Network with Converter Power Supply

System and Their Influence

for Environmental Protection

Zygmunt SZYMANSKI

Silesian University of Technology Gliwice, Poland

Abstract. The paper presents a consequences of application a converter supply

system in electro energetic grid of middle and high voltages, supplied a great

power drive system (over 1000 kW), and their influences on quality of electric en-

ergy in industrial plants. Problems of influence electromagnetic and electrostatic

fields generated from electro energetic grid, on surround environmental is ana-

lyzed in the paper The paper presents a mathematical analysis of phenomenon to

occur in industrial plants of electro energetic grid of middle and high voltages,

with great power load systems. A computer model of electro energetic supply sys-

tem considerate a magnetic and electric field distribution are also presented in pa-

per. For reduction of parasitic harmonics level in current supply and voltage sup-

ply are mostly applied a static capacitor filter. For reduction a negative influences

of magnetic and electric field distribution on surround environments to work up a

special criteria reduced an harmfully interaction. The paper present a solution with

static and active power filters in reduction of high harmonics levels. Some results

of computer simulation performed for selected electro energetic grid configuration,

with and without active filter are presented in the paper. Results of industrial

measurement are also presented in the paper

Key words. electromagnetic compatibility, environmental protection

Introduction

Electromagnetic stability of electro energetic systems, it’s ability of the system for re-

alization of rated work, independently of the level a stochastic and periodic distur-

bances. Those disturbances can be caused by: breakdown work condition of the system

(short circuit state, asymmetrical loading), parallel and series resonances, nonlinear

load and inverter power supply. Power industrial plants are mostly supplied with mid-

dle voltage grid MVn, with short circuits power non-great of 300MVA. Total rated

power of drive systems, supplied with inverter power supply are a dozen of MW. Mu-

tually interaction of the individual supplied drive system, can caused the disturbance

their normally work state. The phenomenon is especially visibly among other things:

during heavy starting of the great power machines, their interaction for ventilator or

pumps supply systems, start of the conveyers (chain or belt), during ride of few electri-

cal wire line locomotives, riding after contact line segment, supplied with rectifier sup-



58

ply station. The interaction can be limited: to increase of the rated power of transformer

supply station, applied of modern control system in converter supply system. The paper

presents a consequences of application of converter supply system in electro energetic

grid of middle voltage, supplied of drive system a great power load systems (over

1000kW), and their influences on quality of electric energy. In the paper presents a

mathematical analysis of phenomenon to occur in industrial plants of electro energetic

grid of middle voltage, with great power load systems. Dynamical state systems ap-

pearance during heavy starting of drive system caused a great voltages drops in electro

energetic supply sets (0,35 U1n

), generated parasitic harmonics in current supply and

voltages supply systems. The paper presents a computer model of electro energetic

supply system of industrial plant with converter supply systems. Together with para-

sitic harmonics compensation, problem of LC resonances between the output filter of

inverter and power active filter and the line inductances are analyzed. For reduction of

parasitic harmonics level in the current supply and in voltage supply, are mostly ap-

plied a static capacitor filter. The paper presents a solution with active power filters in

reduction of parasitic harmonics levels. For reduction a negative influences of magnetic

and electric field distribution on surround environments to work up a special criteria

reduced an harmfully interaction. Some results of computer simulation performed for

selected electro energetic grid configuration, with and without active filter are pre-

sented in the paper. Some results of industrial measurement are also presented in the

paper.

1. Resonance Phenomenon in Electrical Plant Grid

Mains grid of the industrial plant are composed with: overhead air grid conducted in

the steel tower or by cable line, systems of energetic transformer conditioning grid vol-

tage for the level of rated voltages supplied loadings: induction motor, DC motor and

capacitor battery. For analysis of dynamic states of MV grid assumed cascade connec-

tion four terminal network type G: in longitudinal branch finding series connected

elements: Rs and L

s, in transverses branch are included a capacitance of the network

section Cs.

Dynamic state in electro energetic grid of middle voltage can described a

system of differential equations (1):

( )

( )

b

idU

RiU

X

di

b

idU

RiU

X

di

k

kk

kkkk

k

k

k

kk

kkkk

k

k

dtdt

dtdt

11

11

1

11

1

,

1

,

1

−−

−−

−

−−

−

=−−=

=−−=

α

α (1)

where:

αk-1

, αk, b

k-1, b

k – coefficient of matrix four terminal network,

Rk-1

, Rk,

Xk-1

, Xk – longitudinal resistance and reactance of k four terminal network,

Uk-1

, Uk,

ik-1

, ik – voltage and current in input and output of k four terminal network,

The values of coefficients: αk, b

kdepended of industrial grid loading parameters, and

capacity of condenser battery including in grid for static compensation of reactive po-

wer, and for reduction of parasitic harmonics in supply voltages and in currents, re-

ceived with supply sources. Static converters are frequently used in industrial plants in

order to improvement the quality of energy, and in reduction of parasitic harmonics.

Z. Szymanski / Improvement of Electromagnetic Compatibility 59

One of the chosen structures used in plant grid MV is application of the parallel voltage

inverter associated with an LC filter (hybrid active filter). Sometimes, in particularly

coincidences, maybe arise a series or parallel resonance between a reactive elements of

the output filter of voltage inverter, and capacitor banks for reactive power compensa-

tion, and also a static passive filters used in elimination of current harmonics in hybrid

structure of AFP [4]. Simplified scheme of the three-phase network with parallel active

power filter are presented in figure.1. Scheme of electro energetic supply system of the

industrial plant are presented in figure 2.

Figure 1. Simplified scheme of the three-phase network with parallel active power filter

Figure 2. Scheme of electro energetic network 6 kV

Z. Szymanski / Improvement of Electromagnetic Compatibility60

System of differential equations (2) described a transient state of middle voltage

grid:(2)

[ ]] ] ⎥⎦

⎤

⎢⎣

⎡+⎥⎦

⎤

⎢⎣

⎡+

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎣

⎡

=⎥⎦

⎤

⎢⎣

⎡−⎥⎦

⎤

⎢⎣

⎡−⎥⎦

⎤

⎢⎣

⎡=⎥⎦

⎤

⎢⎣

⎡VU

dt

di

LUiiiiCafNi,faC

i,inv

i,afi,invi,inv

i,Li,CFi,n

(2)

[ ] [ ] [ ] [ ] [ ]VUir

dt

di

LV

dt

ud

Ci CafNi,CFi,ni,n

i,n

i,afi,n

i,afC

i,afi,CF

+++

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎣

⎡

=

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎣

⎡

=

After realization of: ab and dq transformations, system equations (2), we can presented

in the form of the system of matrix equations (3):

[ [ ] ]

[ [ [ [ [ [

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎣

⎡

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

+

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎣

⎡

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

+

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎣

⎡

=

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

+

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

+

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

⎥

⎥

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎢

⎢

⎣

⎡

•

•

=

⎥

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎢

⎣

⎡

∗

∗

−

+

w

w

D

D

U

U

D

D

X

X

C

C

s

s

w

w

B

B

U

U

B

B

X

X

IjA

IjA

X

X

qi

cd

w

w

qi,inv

ad,inv

u

u

qi

cd

qi

cd

qi

cd

w

w

qi,inv

ad,inv

u

u

qi

cd

n

n

qi

cd

0

0

0

0

0

0

0

0

0

0

0

0

Θ

Θ

(3)

where:

[ ] [ ] [ ]

[ ] [ ] [ ]

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

=

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

=

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

=

⎥

⎥

⎥

⎥

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎢

⎢

⎢

⎢

⎣

⎡

=

⎥

⎥

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎢

⎢

⎣

⎡

=

⎥

⎥

⎥

⎥

⎥

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎢

⎢

⎢

⎢

⎢

⎣

⎡

−

−−

=

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

=

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

=

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎣

⎡

=−

⎥

⎦

⎤

⎢

⎣

⎡

=⎥

⎦

⎤

⎢

⎣

⎡

00

00

0

0

010

001

0

0

1

1

0

0

0

1

0

0

11

1

00

1

0

,

,

,,1

,

,

,

,

,

,

,

DDC

L

C

B

L

B

CC

L

LL

v

A

V

i

w

i

i

s

v

i

i

X

X

X

T

X

X

wu

n

af

w

af

u

afaf

af

nn

n

Cn

CL

C

Cinv

Cn

C

CCaf

Cinv

Cn

C

q

d

qi

cd

This state presented a linear description of the network system, which allows to use a

high level synthesis tools for the control law of elimination of resonance phenomenon

(norms: H2or H

oo) [3]. On resonance pulse w

0impedance Z

0gives a high impedance. If

one of the sources: Vnet ,

Uinv

, or iload

, contains a current harmonic close to the reso-

nance pulse, the voltage range VP

increases very significantly.[5].Control of resonance

phenomenon with using of control Uinv

voltage will reject perturbations of Vnet

and iload

,

in a frequency range close to resonance pulse w0

. We can applied next possibilities:

direct measurement of voltage VP, and controller generate a voltage V

inv -= - K(jw)V

P,

measurement of current network , and controller generate a voltage Vinv

= K(jw)Inet

,

measurement of current network and inverter, controller generate a voltage Vinv

=

K1(jw)I

net+ K

2(jw)I

inv . With the help of multivariable synthesis tool, a control law is

formulated. This law allows to minimize the transfer of VP

around the resounding

pulse.[5].


2. Power Active Filter in Industrial Plant Network

Growth of drive system supplied with converters supply system, caused considerable

deterioration of the parameter of electrical energy, in plants supply grid system. Con-

siderable level deterioration of current and voltage supply network, required applica-

tion of modern method compensation of deformations. Actual applied static resonance

compensator, besides advantages having a number of faults: rush control reactive pow-

er, limited speed control of the transient power to send for supply grid, great influence

of the supply network parameters for filtering efficiency of passive LC filters, possibil-

ity of appearance of resonances: series and parallels before filter systems and supply

sources. That faults can be reduced by application of the active power filter AFP in

inverter supply system. [1, 2, 4, 5]. AFP can work as: series filter, parallel filter, and

series - parallel filter. Intermediate solution is application of hybrid active filter coop-

erative with passive LC. AFP filter assured effective compensation of parasitic har-

monics in voltage and current, reduced results voltage and currents supply asymmetry;

stabilization of voltage in load terminal, to compensate of voltage drops in the supply

grid reactance and make to possible reactive power compensation. A theoretical model

of the network and real model of the industrial grid supplied a great power plants were

performed with Matlab - Simulink procedures and PSpice simulation programs.

Scheme of computer model of the supply grid presented in figure 3. Results of com-

puter calculation are presented in figure 4.

Figure 3. Simulation model of electro energetic supply system

Ub

+ -v

vab

30/pi

rpm

Powergui

-Continuous

-K-

peak2rms

kaskada_ir

kaskada_Te

kasakada_is

kasakada_Mobc

kabel_207_uab

kabel_207_ia

+i-

iAs1

+i -

iA1

+i

-

iA

do_kasakady_uab

do_kasakady_i

Mobc [N]

Zadawanie

obciazenia

+

-v

Vd2

+

-v

Vd1

+

-v

Vd

+

-v

Vca

+

-v

Vbc

Vb

+

-v

Vab

Uf

Uc

Ua

Terminator1

Terminator

A B C

a b c

TG

6kV/370V

2500kVA

alpha_deg

AB

BC

CA

Block

pulses

Synchronizowany

6-Pulsowy Generator

V [m/s]

Id [A]

alfa

Regulacja pradu

i predkosci obrotowej

A B C

A B C

RPW-5

2x39.8uF/1f 1

0

RMS Vab voltage

A

B

C

A

B

C

RG-3/10

95uF/1f 1

A

B

C

A

B

C

R/X zrodla

A

B

C

pulses

+

-

Przeksztatnik

PGG

N (rpm)

nMobc

Mobc

Wentylator

F+

A+

TL

F-

A-

m

Maszyna Wycigowa

MW

MW_uabnn

MW_iann

MW_V

MW_Ud

MW_Id

In1

In2

In3

MD_RW

A B C

A B C

L2d

A B C

A B C

Kabel: 207

30/pi

Gain

signal

magnitude

angle

Fourier

Ifa

Ifb

Ifc

FP1

m

ir_abc

is_abc

wm

Te

Demux1

em

D [1mH]

0

A

B

C

Tm

a

b

c

m

8 HP - 6000 V

50 Hz - 375 rpm

A

B

C

A

B

C

(R) Kabla: 223

A

B

C

A

B

C

(L) Kabla: 223

1/60*2*pi*3

V [m/s]

ir_a (A)

is_a (A)


Figure 4. Active filter node voltage transient and harmonic analysis

3. Influence of Electromagnetic Field Distribution on Surround Environment

Electromagnetic field is very divers environment factor: static fields ( electrostatic and

magnetic static), low and high frequency fields, to microwave radiation (frequency

below 300GHz) [3, 5]. In environment appears sinusoidal fields, distorted parasitic

harmonics fields, and modulated in different manner electromagnetic fields. Basic data

characterized degree of influence on environment are parameters: basic frequency, in-

tensity of electric field, intensity of magnetic field or flux density, density of radiation

power, exposure time of the worker. [4]. Manner and results electromagnetic fields

influences directly on human body and or physical elements of the work environment

depend on frequency of radiation, density of flux and distance from radiation sources.

Electromagnetic field energy absorb directly in human body induced in body electric

currents and heat up of tissue. It can be of the reason: sleep disturbance, head ache or

giddiness, dullness, partial loss of memory, eyesight disturbance, change of blood im-

age and pressure, immunologic disturbance and finally brain cancer. [3, 5]. Electro-

magnetic field distribution can be described by system of equation (4):

→→⋅→→→→→

⎟

⎠

⎞

⎜

⎝

⎛⋅

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛−

−⎟

⎠

⎞

⎜

⎝

⎛×+= vvEBvEE

v

2

1γ

γ (4)

→→⋅→

→→

→→

⎟

⎠

⎞

⎜

⎝

⎛⋅

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛−

−

⎟⎟

⎟

⎠

⎞

⎜⎜

⎜

⎝

⎛×

−= vvB

Ev

BB

vc

22

1γ

γ

where:

γ – Lorentz factor,

c – light speed,

Analysis of electromagnetic field distribution were realised for different types of grid

plants supply systems with different coefficients of distortion (THD). ANSYS and

JMAG computer program were applied in computer calculation of electromagnetic


fields distribution. Each simulation cycle was carried out in the following steps: speci-

fication of geometry supply system, specification of human location properties, specifi-

cation of boundary condition and excitation sources, generating the solution and

graphical postprocessing and analysis environment emergency degree. Analysis was

performed for two work conditions: static and high frequency fields interaction. Results

of computer calculation are applied to calculation of basic parameters of factor danger-

ous for human body. Boundary data for electric field is – 10 kV/m, and for magnetic

component – 2,5 kA/m. [3]. For high frequency electromagnetic fields particularly

component are equal: 20V/m, and 3A/m, for frequency f (1kHz – 3MHz). [4, 5].

4. Conclusion

Application of the inverter supply system in supply network of the great power drive

system, is a reason of the great voltage drop, increase of reactive power consumption,

and distortion of the transient supply voltages and supply currents. Capacitors static

filter to become that requirement in limited range. Application of the active filter in-

creases effectiveness of reduction level of parasitic harmonics. Application of hybrid

active filter assure simultaneously improvement of reactive power compensation. On

analysis of industrial plant network very important matter is definition of resonance

pulse of the network, and their influences on voltage drop and oscillation of high har-

monics of current and voltage in network. Analysis of electromagnetic fields distribu-

tion and their radiation in high frequency fields enable realization of special protection

system, which reduced negative effect of their fields, and limited their influence on

human body.

References

[1] M. Aredes, K. Heumann, A unified power flow controller with active filtering capabilities, Proceedings

of PEMC’96, vol.III, Budapest, Hungary, 1996 r.

[2] P. G. Barbosa, E. H. Watanabe, Advanced series reactive power compensator based on voltage source

invernters, Conference Proceedings COBEC’95, Sao Paulo, 1995 r.

[3] J. Karpowicz, K. Gryz, Control and shaping of work conditions in electromagnetic fields and radiations,

Work safety nr 10, 2001 r.

[4] Z. Szymański, Modern method of improvement electromagnetic compatibility of electro energetic sets,

with converter power supply system of great work, Proceedings of CPE’05, Gdansk, June, 2005 r.

[5] Z. Szymanski, Analysis of the stability an electro energetic grid with great load converter power supply

system, Proceedings of CPE’07, Gdansk, June, 2007r.


Chapter 2

Electromagnetic Field and Health

Effects of Radiation in Cellular Cultures M Filomena BOTELHO1, A Cristina SANTOS1, M Carmo LOPES2, Marta PINTO3, Isabel CARREIRA3, Inês ALEIXO4, Inês ROLO4, Luís NEVES4, Ricardo COSTA4,

Rosemeyre CORDEIRO4, Cláudia FERREIRA4, Gilberto ALMEIDA4, Hugo TAVARES4, Joana MARQUES4, João CASTRO4, M João BÁRTOLO4

1Instituto de Biofísica/Biomatemática, IBILI, Faculdade de Medicina de Coimbra 2Serviço de Física Médica, IPO-CROC, Coimbra

3Instituto de Biologia Médica, Faculdade de Medicina de Coimbra 4Licenciatura de Engenharia Biomédica, Faculdade de Ciências e Tecnologia da

Universidade de Coimbra, E-mail: [email protected]

Abstract. We aimed to compare eventual biological effects in cellular cultures after X-ray irradiation. Human amnyocytes and rat peritoneal macrophages, irradiated with 3 Gy (G II) and 6 Gy (G III) were compared with a non-irradiated control (G I) over time. Both cell lines were isolated and cultured under aseptic conditions (37ºC, 5% CO2). Cell proliferation and radiation cytotoxic effects were studied with the MTT test Cytogenetic evaluation of amnyocytes was done at 4, 24, 120 and 144 h post-irradiation, showing a correlation between the decrease of the survival rate and the increase of the irradiation intensity, although with some recovery capacity. For rat peritoneal macrophages the 6 Gy were also more harmful, killing the majority of the cells. The 3 Gy dose, although aggressive, enables a higher survival rate.

Introduction

Since the second half of the XXth century, after the discovery of X-rays, the effects of this kind of radiation on living cells has been a subject of intense research. Although there is a lot of information on macroscopic and cytologic induced alterations, little knowledge exists on the mechanism of these changes or the connection between the effects of short wave radiation and environmental conditions. It is extremely important to know the interactions that might occur between radiation sources and living cells, in order to try to evaluate, qualitative and quantitatively, possible lesion risks. Studies of Hayden et al. and Smith in cereals gave a great contribution to determine cause-effect relationships between presence or absence of lesions, genetic effects and chromosomic aberrations due to irradiation with X-rays of barley seeds [1, 2, 3, 4, 5]. When exposed to radiation, cells suffer physical, chemical and biological changes. As cells are a part of the all, these changes will influence tissues, organs and systems, and ultimately the organism [6,7].

Radiation can be non-ionizing or ionizing, depending on its ability to withdraw electrons from the atoms and to form ion pairs. Ionizing radiation is potentially dangerous due to its capacity of producing ions, being responsible for biological damage in living organisms [7]. Chemical (atom binding rupture and free radical formation) and biological phenomena (specific cell function alteration) follow physical


67

properties of radiation which are responsible for the decrease or alteration of activity of the living organism. These are the first reactions to radiation usually happening for relatively low doses. Besides these functional reactions, biological effects are also characterized by morphological variations. Changes of essential functions might induce immediate cell death, if its structure it is considerably damaged [6,7]. Some human cells are highly specialized, for example neurons, while others are constantly renewed. The higher the specialization degree, the slowest is the cell division, being less radiosensitive. For instance, epithelial, intestinal lining or hæmatopoietic cells are more sensible to radiation than other kinds of cells. Exception made to the lymphocytes, although they only divide in very particular conditions [7].

In studies with vegetables it has been seen that X-rays induce two kinds of cytologic alterations, depending if nuclei are in interphase or in division upon irradiation. Primary effects are irregular fragmentation and agglutination of chromosomes when irradiation coincides with the prophase, due to matrix rigidity. As a consequence of agglutination, chromosome movements are irregular and might origine an atypical disposition of the accromatic fuse, pseudo-amythosis, etc.. The secondary effect, due to irradiation during the interphase, will be fragmentation which induces aberrations, with or without subsequent reconstruction of the ends of the fractured chromosome, originating transloccation, inversion, deletion, bridges, fragments, etc. [1].

A complex organism exposed to radiation suffers somatic effects and genetically transmissible effects [8]. Cells have a great capacity of reparing damages throughout a series of mechanisms designated cell rescue. In some cases the damaged cell is still able to divide and the mutated daughter cells either die or replicate the mutation, possibly leading to a malignant tumor. Each organ reacts presenting different levels of tolerance to radiation [7]. According to some studies, there are situations in which one can observe a phenomenon designated low dose hypersensitivity [9]. The clinical condition of an all-body irradiated patient depends on the absorbed radiation dose, expressed by the unit Gray (Gy) – quantity of energy by mass unit of tissue, corresponding to 1 J/Kg of irradiated mass. Very high doses (hundreds of Gy) imply death in a very few minutes; doses such as 100 Gy cause death of the central nervous system and death in a few hours to 1 or 2 days. An all-body dose of tens of Gy induces a gastrointestinal syndrome, dehydration, weight loss, serious infections leading to death in some days. Doses of a few Gy lead to an hæmatopoietic syndrome [6,7]. Litterature on the influence of atmosphere on X-ray effects is scarce, but apparently (both for plants and animals) lesions are smaller in the absence of air. Besides the rate of cell division, the organ sensitivity is also influenced by the organ ranking role in the organism well-being, as well as its oxygen and blood supply [1,8].

Material & Methods

Two different kinds of cells from two different species were chosen - human amnyocytes and rat peritoneal macrophages - for our experimental study, due to previous work developed in our lab. The human amnyocytes were isolated from amnyocentesis fluid and cultured in flasks with the indicated media, in asseptical conditions at 37ºC, in an enriched 5% CO2 atmosphere [10]. The peritoneal macrophages were collected from Wistar rats two months old [11]. After collection, the macrophages were cultivated in flat bottom multiwell plates with complete RPMI-1640

M.F. Botelho et al. / Effects of Radiation in Cellular Cultures68

medium with L-glutamine and recommended antibiotics, also at 37ºC in a 5% CO2 atmosphere.

After propagation, the amnyocytes were divided into three culture flasks: flask I was the non-irradiated control; flask II was irradiated with 4 MeV X-rays in a Varian – Clinac 600C accelerator for 67.2 sec corresponding to a 3 Gy dose; flask III was irradiated for 134.4 sec receiving a 6 Gy dose. One hour after irradiation, 100 μl of colcemide were added to the aliquots in order to inhibit the accromatic fuse formation. Samples were kept for 3 h at 37ºC (Heraus Instruments Incubator function line EG 110I, Line A JOUAN, SHELLAB). Manipulation and cell fixation for cytogenetic evaluation were done at 4 h (T0), 24 h (T1), 120 h (T2) and 144 h (T3) post-irradiation. The slides with the fixed cells were observed using a contrast phase optical microscope (NIKON Japan 60). To evaluate cell proliferation and radiation cytotoxic effects, the colorimetric MTT test [3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide] (Sigma-Aldrich, St. Louis, Missouri, USA) was used at this point, enabling the counting of living cells 6:30h, 42:30h, 120h and 146h after irradiation. Images were obtained with a contrast phase optical microscope (NIKON Eclipse TS 100) and colour intensity was measured by microELISA (at 570 nm, with a ref. filter of 620 nm).

The rat macrophages were splitted into three groups: group I –control; group II – cells irradiated with 3 Gy; and group III – cells irradiated with 6 Gy. After irradiation, the multiwell plate was incubated in the previously referred conditions for 2:30h. This wasconsidered our time 0 (T0); time-1 (T1) = 8 h post-irradiation; time-2 (T2) = 48 h after irradiation; time-3 = 58 h post-irradiation. Cell viability was evaluated also using the MTT test [12]. Visual control was achieved with a contrast phase optical microscope and colour intensity was measured by microELISA (at 570 nm, with a ref. filter of 620 nm).

Results

In human amnyocyte cytogenetic studies, for times T1 and T3, the cells irradiated with a 6 Gy dose showed more lesions and/or isolated chromosome fragments when compared to the ones irradiated with 3 Gy (Table 1). The surviving cells showed, along time, in both samples (3 Gy and 6 Gy), ability to recover, nevertheless a more significant recovery was verified for the 3 Gy dose (Fig. 1). Using the cytotoxicity test we observed a decrease of the viable cells rate, from 88.89% to 66.66% in the 3 Gy sample and from 70.37% to 45,94% in the 6 Gy irradiation.

In what concerns the rat macrophages, cell survival rate of the control culture has been considered the standard for all samples. For T0 (2:30h) cell survival has been 100% for all samples (control, 3 Gy and 6 Gy); for T1 (8h) cell survival was 90% for the 3 Gy dose and 80% for the 6 Gy irradiation; for T2 (48h) values were, respectively, 71.43% and 28.60% (Fig. 2); for T3 (58h) the survival rate was 70% for 3 Gy and 25% for 6 Gy.

M.F. Botelho et al. / Effects of Radiation in Cellular Cultures 69

Table 1. Chromosomic study of 30 metaphases.

Fig. 1. Results of human amnyocytes’ cytogenetic study performed in 30 metaphases.

Control (T1) 3 Gy (T1)

6 Gy (T1) 6 Gy (T3)

2 (in plates also with pieces) 11 (1 broken chromosome) 17 6 Gy

0 0 30 3 Gy

1 0 29 Control

(144h) T3

10 (9 of which in plates with pieces) 25 4 6 Gy

4 (1 rupture in a plate with 1 piece) 9 (1 plate with pieces) 18 3 Gy

0 1 29 Control

(24h) T1

Ruptures Pieces ormal N Study

M.F. Botelho et al. / Effects of Radiation in Cellular Cultures70

Fig. 2. Some images of viability/cytotoxicity MTT tests of rat peritoneal macrophag

Discussion & Conclusions

The human amnyocyte cell line showed, after irradiation in oconditions, a significant decrease of the survival rate. They showed somthe proliferation rate was correlated with the irradiation intensity.

The rat peritoneal macrophages showed that a 6 Gy irradiation ikilling the majority of the cells. The 3 Gy dose, although aggressive, survival rate. Time is also an important factor and cell death is proponumber of living cells decreases with time and dose intensity.

References

[1] B. Hayden, L. Smith, The relation of atmosphere to biological effects of X-rays,1949.

[2] L. Smith, Hereditary susceptibility to X-ray injury in. Triticum monococcum, Ame1942.

[3] L. Smith, Relation of polyploidy to heat and x-ray effects in the cereals, J. Hered. 3[4] L. Smith, A comparison of the effects of heat and X-rays on dormant seeds of

reference to polyploidy , J. Agric. Res. 73: 137-158, 1946. [5] L. Smith, The aceto-carmine smear. Technic, Stain Tech 22: 17-31, 1947. [6] F. A. Mettler, A. C. Upton, Medical effects of ionizing radiation, Grune & Str

Florida, 1995. [7] National Council on Radiation Protection (NCRP), Report 93, USA, 1987. [8] B. Buddemeir, Understanding radiation and its effects, in LLNL Counter ter

response program. LLN Laboratory ed, California, 2006. [9] M. C. Joiner, B. Marples, P. Lambin, S. C. Short, I. Turesson I, Low-Dose Fr

Potentiates the Effects of Paclitaxel in Wild-type and Mutant p53 Head and Neck TJ Radiat Oncol Biol Phys 49: 379-389, 2001.

[10] H. E. Wyandt, V.S. Tonk, X.L. Huan, A.T. Evans, J.M. Milunsk, A. MilunAbnormal Rapid FISH and Chromosome Results from Amniocytes for Prenatal DiTher 21: 235-240, 2006.

[11] D. M. Weir, Handbook of experimental immunology, vol 2, Blackwell Scientific P1973.

[12] T. Mossman, Rapid Colorimetric Assay for Cellular Growth and Survival: Applicand Cytotoxicity Assays, J Immunol Meth 65: 55-63, 1983.

control 3 Gy 6 Gy

control 3 Gy 6 Gy

M.F. Botelho et al. / Effects of Radiation in Cellular Cultures 71

T1 (8h)

es for T1 & T2.

ur experimental e recovery, and

s more harmful, enables a higher rtional to it. The

Genetics 34: 26-43,

r J Bot 29: 189-191,

4: 130-134, 1943. cereals with special

atton, Inc., Orlando,

rorism and incident

actionated Radiation umor Cell Lines, Int

sky, Correlation of agnosis, Fetal Diagn

ubl, 2nd ed, Oxford,

ation to Proliferation

T2 (48h)

Influence of Static Electric Field Generated Nearby High Voltage Direct Current

Transmission Lines on Hormonal Activity of Experimental Animals

Grzegorz CIESLAR a,1, Paweł SOWA b, Beata KOS-KUDLA c, Aleksander SIERON a aDepartment and Clinic of Internal Diseases, Angiology and Physical Medicine,

Medical University of Silesia, Bytom, Poland bInstitute of Power System and Control,

Silesian University of Technology, Gliwice, Poland cDepartment of Pathophysiology and Endocrinology,

Medical University of Silesia, Zabrze, Poland

Abstract. The aim of the study was to estimate the effect of static electric fields with physical parameters generated nearby HVDC transmission lines on hormonal system of experimental animals. 96 male Wistar rats were exposed for 56 consecutive days (8 hours daily) to static electric field with intensity of 16, 25 and 35 kV/m respectively, while 32 control rats were shame-exposed. Exposure to static electric fields evoked transient stimulation of insulin and thyroid hormones secretion as well as decrease in serum corticosterone level. As observed effects appeared mostly for intensity above 16 kV/m in prepared recommendations potential harmful effect of electric fields with such intensities should be regarded.

Keywords. Static electric field, High Voltage Direct Current transmission lines, hormonal activity, rats

Introduction

The results of experimental studies suggest that different forms of electric field affect significantly hormonal activity of hypophysis, adrenal cortex, thyroid gland and testes of experimental animals, probably as a result of stimulation by this physical factor - acting as a non-specific stressor – the activity of hypothalamus-hypophysis-peripheral glands system or direct effect on synthesis and secretion of particular hormones.

The divergence of obtained results is related mainly to different physical parameters of electric field and experimental models used by particular authors. Nowadays transport of electric power using air High Voltage Direct Current (HVDC) transmission lines becomes very popular.

Regarding the lack of reports dealing with the influence of strong static electric fields on activity of endocrine glands in available literature, the aim of the study was to

1 Corresponding Author: Grzegorz Cieślar, Department and Clinic of Internal Diseases, Angiology and Physical Medicine, Medical University of Silesia, Batorego St. 15, PL-41902 Bytom, Poland, E:mail: [email protected]



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estimate the effect of static electric fields with physical parameters generated nearby HVDC transmission lines on hormonal system of experimental animals.

1. Material and Methods

Experimental material consisted of 128 male Wistar albino rats aged 6 weeks, weighting about 150 g. During the whole experiment all animals were placed in identical environmental conditions (constant temperature 22 ± 1oC and humidity of air) under a 12 h light-dark cycle) and fed with standard laboratory pellet food Labofed B (15g per day) and free access to tap water.

All animals were randomly divided into 4 equal groups (32 animals each) with no significant differences in body weight. Two weeks before the beginning of exposure cycle rats from all groups were adapted to new environmental conditions in room, in which subsequently whole experiment was performed. This adaptation process and optimal environmental conditions in a specially designed room enabled to exclude the influence of other factors than electric field action on hormonal activity of experimental animals.

1.1. Procedure of Exposure to Static Electric Field

The animals from 3 experimental groups were exposed for 56 consecutive days (8 hours daily, alternately between 700÷1500, 1500÷2300 and 2300÷700, similarly as in case of electric current transmission lines staff working in shifts) to static electric field with different electric field intensity values in a specially designed experimental system consisting of autotransformer, high voltage transformer 220V/60000V, cascade rectifier, water rheostat, 2 electrodes with round shape and specially profiled edges placed in a distance of 50 cm from each other, typical plastic cage placed between both electrodes containing 8 animals at a same time and magnetostatic kilo-voltmeter C196 type.

Rats from first experimental group were exposed to static electric field with intensity of 16 kV/m, rats from second experimental group were exposed to static electric field with intensity of 25 kV/m and rats from third experimental group were exposed to static electric field with intensity of 35 kV/m. The control animals were subjected to sham-exposure in the same experimental system, during which no electric field was generated between electrodes.

Taking into account the lack of regulations limiting the parameters of exposure to static electric field generated nearby High Voltage Direct Current transmission lines, in selection of analyzed electric field intensity values actual obligatory norms for occupational exposure to variable electric fields with frequency above 1 Hz as well as results of measurements of electric field intensity in the corridor of actually existing HVDC transmission lines were included.

The lowest value of chosen electric field intensity – 16 kV/m is contained within the range of permissible norm for variable electric fields in conditions of occupational exposure, intermediary value of 25 kV/m corresponds with typical values of static electric field intensity observed in „corridor” of actually existing HVDC transmission lines and highest value of 35 kV/m conforms to top level of electric field intensity, which occur sometimes in close proximity of electric field transmission lines in especially unfavorable weather conditions.

G. Cieslar et al. / Influence of Static Electric Field 73

1.2. Biochemical Analysis

At 14th, 28th and 56th day of exposure cycle and then at 28th day after the end of exposure cycle a part of animals from all groups (8 rats at a same time) was exsanguinated in Morbital narcosis (50 mg/kg of body weight i.p.) between 800 and 1000 a.m. regarding daily profile of concentration of some hormones with highest excretion level in the morning. Then the collected blood (6-8 ml) was decanted and centrifuged and in obtained serum the concentrations of some hormones as insulin, glucagon, adrenocorticotropin, corticosterone, triiodothyronine, thyroxine and testosterone were estimated. Concentration of particular hormones were determined by means of radioimmunologic method using respectively: Rat Insulin RIA Kit RI-13K (LINCO Research St. Charles, MI, USA), Glucagon Radioimmunoassay (RIA) Kit RK-028-02 (Phoenix Peptide, Belmont, CA, USA), DSL-2300 ACTH Radioimmunoassay (RIA) Kit, DSL-80100 Rat Corticosterone Radioimmunoassay (RIA) Kit, DSL-3100 ACTIVE Triiodothyronine (T3) Coated-Tube Radioimmunoassay (RIA) Kit, DSL-3200 ACTIVE Thyroxine Coated-Tube Radioimmunoassay (RIA) Kit and DSL-4000 ACTIVE Testosterone Coated-Tube Radioimmunoassay (RIA) Kit (all Diagnostic Systems Laboratories, Inc., Oxon, Great Britain).

1.3. Statistical Analysis

The results of measurements presented as mean values ± SEM for particular groups were subjected to statistical analysis by means of analysis of variance (Kruskal-Wallis ANOVA test) with subsequent detailed analysis of differences between particular groups by means of post-hoc U-Mann-Whitney’s test.

2. Results

Mean values of serum concentrations of particular hormones in succeeding days of experiment in all experimental groups of rats are presented in Table 1.

Mean serum concentration of insulin at 14th day of exposure cycle in group 16 kV/m was significantly higher comparing to control group (by 110,3% (p=0,012)). In other groups of animals exposed to electric field mean serum concentration of this hormone did not differ significantly in comparison with control group. At 28th day of exposure cycle mean serum concentration of insulin in group 16 kV/m did not differ significantly comparing to control group, while in groups 25 kV/m and 35 kV/m it was significantly higher in comparison with control group (by 38,8% (p=0,046) and 67,0% (p=0,046), respectively). At 56th day of exposure cycle mean serum concentration of insulin in groups 16 kV/m and 25 kV/m was significantly higher in comparison with control group (by 59,1% (p=0,012) and 90,2% (p=0,006), respectively), while in group 35 kV/m it did not differ significantly comparing to control group. At 28th day after the end of exposure cycle mean serum concentration of insulin in groups of rats exposed to electric field did not differ significantly in comparison to control group.

G. Cieslar et al. / Influence of Static Electric Field74

Table 1. Serum concentrations of particular hormones (mean value ± SEM) in succeeding days of experiment in groups of rats exposed to static electric field and in control one.

Day of experiment Hormone Group of rats

14 day of exposure

28 day of exposure

56 day of exposure

28 day after the end of exposure

Control 0.852±0.104 1.318±0.150 0.407±0.044 0.863±0.223 16 kV/m 1.791±0.218 1.906±0.279 0.648±0.055 1.007±0.127 25 kV/m 1.115±0.177 1.831±0.203 0.775±0.106 0.878±0.117

Insulin [ng/ml]

35 kV/m 1.006±0.131 2.202±0.319 0.617±0.084 0.892±0.083 Control 8.12±1.34 12.21±2.07 34.02±5.58 34.20±7.55 16 kV/m 8.30±0.45 7.17±0.96 40.49±5.87 25.02±4.02 25 kV/m 13.86±2.23 6.27±1.10 24.27±5.19 32.44±5.04

Glucagon [pg/tube]


ACTH [pg/ml]


Corticosterone [ng/ml]


Triiodothyronine[ng/dl]

35 kV/m 257.49±8.05 259.50±6.97 327.98±21.08 360.66±10.26 Control 4.016±0,289 6.319±0.381 4.109±0.260 3.560±0.207 16 kV/m 5.272±0.302 8.128±0.351 5.370±0.262 3.835±0.243 25 kV/m 5.357±0.305 7.808±0.788 4.749±0.418 3.437±0.246

Thyroxine [ng/dl]


Testosterone [ng/ml]

35 kV/m 3.178±0.967 5.758±1.533 6.396±1.639 5.066±2.224

Mean serum concentration of glucagon at 14th day of exposure cycle in groups 16 kV/m and 25kV/m did not differ significantly in comparison with control group, while in group 35 kV/m it was significantly higher comparing to control group (by 65% (p=0,016)). At 28th day of exposure cycle mean serum concentration of glucagons in group 16 kV/m did not differ significantly in comparison with control group, while in groups 25 kV/m and 35 kV/m it was significantly higher comparing to control group (by 48,6% (p=0,046) and 44,3% (p=0,046), respectively). At 56th day of exposure cycle mean serum concentration of glucagons in groups 16 kV/m and 25 kV/m did not differ significantly in comparison with control group, while in group 35 kV/m it was significantly lower comparing to control group (by 48,9% (p=0,027)). At 28th day after the end of exposure cycle mean serum concentration of glucagon in groups of rats exposed to electric field did not differ significantly in comparison to control group.

Mean serum concentration of adrenocorticotropin (ACTH) at 14th day of exposure cycle in groups 16 kV/m and 25 kV/m did not differ significantly in comparison with control group while in group 35 kV/m it was significantly lower comparing to control group (by 31,2% (p=0,009). At 28th and 56th day of exposure cycle and at 28th day after the end of this cycle mean serum concentration of adrenocorticotropin in groups of rats exposed to electric field did not differ significantly in comparison with control group.


Mean serum concentration of corticosterone at 14thday of exposure cycle in all groups of animals exposed to electric field (16 kV/m, 25kV/m i 35kV/m) was significantly lower in comparison to control group (by 34,3% (p=0,046), 36,8% (p=0,046) and 50,7% (p=0,006), respectively). At 28th day of exposure cycle mean serum concentration of corticosterone in group 16 kV/m did not differ significantly comparing to control group, while in groups 25 kV/m and 35 kV/m it was significantly lower in comparison with control group (by 41,5% (p=0,036) and 78,1% (p=0,002), respectively). At 56th day of exposure cycle and at 28th day after the end of this cycle mean serum concentration of corticosterone in groups of rats exposed to electric field did not differ significantly in comparison with control group.

Mean serum concentration of triiodothyronine at 14th day of exposure cycle in all experimental groups did not differ significantly comparing to control group. At 28th day of exposure cycle mean serum concentration of triiodothyronine in group 16 kV/m did not differ significantly comparing to control group, while in groups 25 kV/m and 35 kV/m it was significantly higher in comparison with control group (by 16,1% (p=0,021) and 24,9% (p=0,002), respectively). Also at 56th day of exposure cycle mean serum concentration of this hormone in group 16 kV/m did not differ significantly comparing to control group, while in groups 25 kV/m and 35 kV/m it was significantly higher in comparison with control group (by 23,0% (p=0,046) and 28,8% (p=0,036), respectively). At 28th day after the end of exposure cycle serum concentration of triiodothyronine in group 16 kV/m did not differ significantly comparing to control group, while in groups 25 kV/m and 35 kV/m it was significantly higher in comparison with control group (by 25,6% (p=0,006) and 32,2% (p=0,003), respectively).

Mean serum concentration of thyroxine at 14th day of exposure cycle in all groups of animals exposed to electric field (16 kV/m, 25 kV/m and 35 kV/m) was significantly higher in comparison with control group (by 31,3% (p=0,016), 33,4% (p=0,012) and 57,8% (p=0,002), respectively). Similarly at 28th day of exposure cycle mean serum concentration of thyroxine in all groups of animals exposed to electric field (16 kV/m, 25 kV/m and 35 kV/m) was significantly higher in comparison with control group (by 28,6% (p=0,006), 23,6% (p=0,046) and 50,9% (p=0,001), respectively). At 56th day of exposure cycle mean serum concentration of thyroxine in group 16 kV/m was significantly higher comparing to control group (by 30,7% (p=0,009)), while in other experimental groups concentration of this hormone did not differ in comparison with control group. At 28th day after the end of exposure cycle mean serum concentration of thyroxine in groups of rats exposed to electric field did not differ significantly in comparison with control group.

Mean serum concentration of testosterone at 14th day of exposure cycle in all groups of animals exposed to electric field (16 kV/m, 25 kV/m and 35 kV/m) was significantly higher in comparison with control group (by 666,5% (p=0,006), 657,7% (p=0,021) and 692,0% (p=0,005), respectively). At 28th and 56th day of exposure cycle and at 28th day after the end of this cycle mean serum concentration of testosterone in experimental groups did not differ significantly in comparison with control group.

3. Discussion

The observed effect of exposure of experimental animals to static electric field resulting in transient significant increase in insulin, thyroxine, triiodothyronine and testosterone activities during exposure cycle, as well as significant decrease in


corticosterone activity in early phase of exposure cycle with subsequent normalization of this activities after the end of exposure approximate typical two-phase stress reaction to external stimulus as e.g. immobilization [1]. Unfortunately, lack of data dealing with the influence of static electric field on activity of hormonal axis hypothalamus-pituitary gland-peripheral glands in attainable literature does not allow to confirm univocally the hypothesis on stress origin of obtained effects.

It seems that results of experimental studies on hormonal effects of variable electric fields with similar values of electric field intensities could support this hypothesis. Exposure of male mice to electric field (frequency 50 Hz, intensity 10 kV/m) [2] and (frequency 60 Hz, intensity 25, 50 kV/m) [3] led to increase in morning corticosterone level with subsequent normalization during further exposure. On the other hand exposure of rats to electric field (frequency 60 Hz, intensity 15 kV/m) [4] and (frequency 60 Hz, intensity 64 kV/m) [5] evoked significant decrease in corticosterone level and both in corticosterone and testoterone level, respectively. Finally exposure of rats to electric field (frequency 50 Hz intensity 50 Hz) [6] caused a slight decrease in triiodothyronine concentration without any significant changes in corticosterone and thyroxine level, while exposure of young rabbits to electric field with the same parameters resulted only in decrease in corticosterone level [7].

Presented results indicate that electric fields could influence hormonal activity of adrenal gland, thyroid gland and testicles in experimental animals both by activation of physiological hormonal axis or by direct stimulation of synthesis and secretion of hormones in particular glands. The divergence of time dependence and direction of obtained changes in hormone concentrations are due to different physical parameters of electric field and experimental models used.

Taking into account that observed hormonal effects of electric field action were intensity-related and they appeared mostly for intensity values above 16 kV/m, it seems that intensity values of static electric field nearby planned High Voltage Direct Current transmission lines must not exceed level of 16 kV/m.

4. Conclusions

1. Long-term exposure of rats to strong static electric fields with intensity generated nearby High Voltage Direct Current transmission lines evokes transient stimulation of excretion of insulin and thyroid hormones as well as decrease in corticosterone level probably in the course of long-lasting stress reaction caused by electric field action.

2. The observed hormonal effects of electric field action were intensity-related and they appeared mostly for intensity values above 16 kV/m.

3. In prepared recommendations potential harmful effect of electric fields with such physical parameters should be taken into account, and intensity values of static electric field nearby planned High Voltage Direct Current transmission lines must not exceed level of 16 kV/m.

Acknowledgements

Study was supported by grant of ministry of Education and Science (2004-2007) as research project PBZ-KBN-098/T09/2003


References

[1] D. Rai, G. Bhatia, T. Sen, G. Palit, Comparative study of perturbations of peripheral markers in different stressors in rats, Can. J. Physiol. Pharmacol., 81 (2003), 1139-1146.

[2] L. DeBruyn, L. DeJager, Electric field exposure and evidence of stress in mice, Environ. Res. 65, (1994), 149-156.

[3] R. Hackman, H. B. Graves, Corticosterone levels in mice exposed to high intensity electric fields, Behav. Neural. Biol., 32 (1981), 201-213.

[4] A. A. Marino, T. J. Berger, B. P. Austin, R. O. Becker, F. X. Hart, In vivo bioelectrochemical changes associated with exposure to extremely low frequency electric fields, Physiol. Chem. Phys., 9 (1977), 433-441.

[5] M. J. Free, W. T. Kaune, R. D. Phillips, H. C. Cheng, Endocrinological effects of strong 60 Hz electric fields on rats, Bioelectromagnetics, 2 (1981), 105-121.

[6] R. Portet, The thyroid and adrenal glands in rats chronically exposed to an intense electric field, C R Seances Soc. Biol. Fil., 177 (1983), 290-295.

[7] R. Portet, J. Cabanes, Development of young rats and rabbits exposed to a strong electric field, Bioelectromagnetics, 9 (1988), 95-104.


Classifying Endogenous Rhythms in Pacemaker ECG Signals

Agnieszka DURAJ (1), Andrzej KRAWCZYK (2)

(1) Institute of Computer Science, Technical University of Lodz, 93-005 Łódź, ul. Wólczańska 215, [email protected],

(2) Central Institute for Labour Protection (2) 00-701 Warsaw, ul Czerniakowska 16, [email protected]

Abstract. This article presents the problem of classification of endogenous rhythms with electrocardiography signals coming from patients with implanted cardiac pacemaker. Efficiency of detection of QRS complex was examined by algorithms working in time domain. During the investigation attention was paid to proper selection of level decomposition, good choice of detection threshold as well as choice of wavelet transformation. In case of identification of endogenic rhythm attention was paid to architecture of feedforward neural network, selection of teaching file and the accuracy of classification depending on the activation function used.

Keywords. wavelet neural networks, QRS complexes, pacemaker signals

Introduction

In recent years, a fast-paced development of processing methods of biomedical signals could be observed, offering new diagnostic possibilities. In addition to the methods using signals derivatives and neural networks, the time-frequency routines are becoming more and more popular, especially wavelet transforms and solutions combining several methods (e.g. wavelet neural networks). Prior works referred to utilizing the aforementioned methods (neural networks, wavelet transforms or signal’s derivatives) for the purpose of QRS complex detection [1-6]. Electrocardiographic signals from freely accessible Internet MIT-BIH database [7] were taken into consideration.

The Massachusetts Institute of Technology – Beth Israel Hospital Arrhythmia Database (MIT-BIH) contains eight directories with various disorders detected using Holter method. Most commonly examined are the 48 records from MIT-DIB directory, which contain the signal file, the header file (contains the patient's information) and the file of diagnostic data (contains the signal in the binary form). Sampling frequency of those signals is 360 Hz and the resolution is 12 bit.

For the purpose of the conducted research considering the QRS complex detection and concurrent classification of patient’s endogenous rhythm, the database of electrocardiographic signals from patients with implanted pacemaker systems was assembled. Analysis of specialist literature on the subject gives more hope for enhancement of accuracy and reliability of algorithms by combining various digital


79

signal processing technologies. In the paper the results obtained for 150 pacemakers ECG signals made available by the Institute of Cardiology in Warsaw will be presented. Those signals came from patients with implanted cardiac pacemaker produced by Biotronik company and recorded by Holter method with sampling frequency of 128 Hz and resolution of 8 bit. We checked the frequency of pacemaker working. In case of 150 ECG pacemakers signals, which it was discussed, it turned out that all of signals were characteristic the different proportion of the endogenic or pacemaker rhythms (Fig. 1).

In this paper the results of the research works related to the classification of endogenous rhythm are presented. The tests were performed using several neural network structures, considering several training sets. Also, two methods of division were used (split-sample and cross-validation) and the best number of neurons in particular layers was tested. Also, the research works related to the selection of activation functions were conducted on selected neural network structures with 1 to 4 hidden layers.

The Methodology of the Research

In order to realize research on QRS complex detection and its classification on the endogenous rhythm of a patient with implanted cardiac pacemaker device, the intuitive concept of wavelet neural network (WNN) was used. At the first stage the decomposition of electrocardiographic – pacemaker signal was performed, which gave the vector of all the QRS complexes occurring in electrocardiographic – pacemaker signal. At the second stage, for the purpose of classification of endogenous rhythm and patient’s artificial rhythm, several feedforward neural networks were used, i.e. single, double and triple layered networks of tangensoidal and sigmoidal activation function. Thus, the structure of the entire system is qualified by suitable choice of the wavelet and the neural network. Some authors, in order to finish the neural network training, recommend aborting the training after predefined iteration (the so-called epoch number) In case of the analyzed set of the electrocardiographic – pacemaker signals, the hold-out method was applied, which sets the breakpoint of the training process at the moment of the minimal test error. In the literature of the subject both negative [8] and positive [9] opinions concerning this methodology can be found.

Also, the appropriate selection of the input data set is of an essential issue. Analysis of the literature on the subject indicates the existence of several methods related to dividing that data set into the training set and the testing set. The database was divided into training set and testing set using two methods: • split-sample, the most often used method; • cross-validation, where the set is divided into k almost equinumerous sets, out of

which (k-1) take part in the learning process. It is also worth mentioning, that in the case of research on medical diagnostics it is important to take into consideration in the learning process a well selected part of the set, one that includes all characteristic cases. The methods of division of the set, in case of medical data, are described in paper [10], pointing out, that the best method is the cross-validation method. According to the author, too small k leads to understated estimation due to big difference between the number of training sets used in the cross-validation and the size of the full database.

A. Duraj and A. Krawczyk / Classifying Endogenous Rhythms in Pacemaker ECG Signals80

Figure 1. Exemplary pacemaker ECG signals a) stym005; b) stym014; c) stym025 d) stym037

Another important issue is the selection of the adequate neural network architecture,

which comes down to specifying the appropriate number of hidden layers and the quantity of neurons in them. In the case of the issue being discussed, the number of the input and the output layers is determined by the examined task. In many research papers directly related to the classification of the medical data, the problems concerning the selection of optimal neural network architecture are very rarely discussed. In majority of the works the optimization of the medical data (e.g. the patient's) is performed and the specific structure of neural network is given, for which the best result was obtained. In the aforementioned researches the observation of only several neural network structures was performed, from one to four hidden layers. For each structure the number of hidden neurons was modified, according to the following vector: nu=[10,20,30,40,50,60,70]. Additionally, the principle was applied, that for networks of n hidden layers, if the first layer was composed of N neurons, the second one will undergo change consequently according to the sequence 5,10,...,N. For each kind of network the two aforementioned ways of determining initial weights were used. Each kind of network was trained until almost perfect recognition of the training set, in other words until obtaining training error E=10-3. In the training process the error back-propagation algorithm was used.

Endogenous Rhythm Recognition – Research Results

As it was mentioned above, the researches were performed for several training sets. For two disjoint sets, where the first set included only the endogenous QRS complexes, the second one included only the pacemaker QRS complexes and the third set including mixed number of endogenous and pacemaker QRS complexes.

Following the process of detecting QRS complex, further research was on the recognition of endogenous rhythm - own rhythm of a patient with implanted pacemaker. The activity of several feedforward neural networks was examined. The result of training a particular neural network structure by particular training sets were

A. Duraj and A. Krawczyk / Classifying Endogenous Rhythms in Pacemaker ECG Signals 81

very similar and were within the margin of error E=0.001. It was noted, however, that the more numerous the training set, the more exact the classification.

Simulation research began with a set of 5000 QRS complexes. Each of the three sets was being scaled up by 1000 QRS complexes and the experiments were performed. Scaling up the set was finished at the number of 12000. As result of the observation, along with the number of the training set the accuracy of classification increases, as shown in Fig.2.

5000 6000 7000 8000 9000 10000 11000 1200094.5

95

95.5

96

96.5

97

97.5

98

Figure 2. The relationship between the classification accuracy and the training set number.

Sequent research works were related to the division of the data set into the training

set and the testing set, using two methods as following: split-sample and cross-validation. For the two prepared sets including only the endogenous QRS complexes or only pacemaker QRS complexes, no differences in accuracy of classification between the aforementioned set division methods were noticed. For the third set, which included mixed number of QRS complexes (endogenous as well as pacemaker), better results were obtained using the cross-validation method. Mean difference between the set division methods is 0,37%. Sample results are given in Table 1.

Table 1 Average accuracy for division of the data set.

Metod Average accuracy [%] Split sample 97,45 Cross-validation 97,82

It should be noticed that in case of electrocardiographic signals containing very

large number of pacemaker QRS complexes in comparison to endogenous QRS complexes (or the other way round), each kind of neural network, except for the two-layered structure with 10 neurons in the hidden layer, classified the QRS complexes in 100%. Different results were obtained for signals with diverse number of endogenous and pacemaker QRS complexes. Sample results for four signals with endogenous rhythm content ratio accordingly of 74% (stym032), 58% (stym121), 45% (stym037), 32% (stym095) are shown in Table 2.


Considering the four kinds of neural networks, the best results in most signals were obtained with the structure with two hidden layers. However, after analyzing thoroughly the aforementioned results, it should be noted that the dependency between endogenous rhythm detection and the applied network architecture is not big. So it is not possible to unambiguously state that three-layered network with n hidden neurons detects the endogenous QRS complexes best. The results lack regularity which could prove such statement. The maximum existing difference in accurate classification of endogenous rhythm, depending on the number of layers, is 0,97%.

Table 2. Mean percentage of proper endogenous rhythm classification, for signals with diverse number of endogenous and pacemaker QRS complexes, for neural networks with 1 to 4 hidden layers.

No signal Numer

of engogenic QRS

% of proper endogenous QRS for neural networks with 1 to 4 hidden layers

1 2 3 4 Stym032 60121 96,95 98,99 98,98 98,99 Stym037 46620 97,99 98,95 98,68 97,97 Stym095 30982 96,94 98,97 97,37 98,99 Stym121 57356 96,95 98,98 98,56 99,98

It is difficult to determine the most optimal number of neurons in the hidden layers

of neural networks. The results from the conducted analysis are that in case of: • 105 examined signals the best results are obtained for 30 (53 signals) and 40

(52 signals) neurons in the hidden layers; • for 33 signals the best number of hidden neurons is 20 neurons in the hidden

layer; • for 12 examined signals results of the network’s activity for various number

of neurons in hidden layers were identical (the differences were 0.01%). The researches did not confirm, however, the opinion functioning in literature on

the subject about better generalization ability of networks with lesser number of neurons. The number of 40 neurons is a central value of the examined vector nu.

The choice of a suitable neural network architecture is also connected with the selection of the activation function. In the conducted research two activation functions were examined: sigmoidal and tangesoidal. It was noted that the sigmoidal activation function shows bigger percentage of accuracy for neural networks with one or two hidden layers. For NN with three or four hidden layers the obtained results suggest, that the use of tangesoidal activation function is more justified. The differences between the examined accuracy of NN, depending on the applied activation function, are relatively small.

Each kind of network (from two-layered to five-layered) was a subject of analysis for the two aforementioned activation functions. During the examination the value of the β parameter was also a subject to changes, β=1, 5, 15, 25. It was noticed, that for the examined neural networks, with both activation functions applied, the poorest results (at the level of 89% of accurate classification) are obtained for the value of parameter β=1. The change of the parameter to β=5 makes it possible to detect the endogenous rhythm at the level as high as over 96%. Mean results of individual kinds of neural network for sigmoidal and tangesoidal activation functions with value of parameter β=15 are illustrated in Fig. 3.

On the basis of the above Fig. 2, it can be noticed that sigmoidal activation function


shows higher percentage of accuracy for neural networks with one and with two hidden layers. For networks with three and four hidden layers the obtained results suggest that application of the tangensoidal activation function is more justifiable. The differences between the examined networks accuracies, depending on the activation function applied, are relatively small.

97,1

97,2

97,3

97,4

97,5

97,6

97,7

97,8

1 2 3 4

sigmoidalna tangesoidalna

Figure 3 The accuracy of endogenous rhythm classification in dependency with the choice of the activation function for neural networks with 1 to 4 hidden layers.

Conclusions

The conducted researches indicate that the collected database of 150 pacemaker electrocardiographic signals is insufficient to decidedly determine that accuracy of three-layered network of 30 (40) neurons, for which on average the best endogenous QRS classification accuracy was obtained, could be recognized as the optimal one. Differences in the obtained results for the particular neural network structures are very small and they only point out to some regularities. They are of more research than clinical value. The sequent researches will be related to the optimization methods of neural networks. This work was partially supported by the Ministry of Science and Higher Education, Poland, grant No. 3 T10A 066 30

Reference

[1] A. Duraj, A. Krawczyk, E. Koźluk, M. Kumor, Zastosowanie przekształcenia falkowego do detekcji zespołu QRS, Przegląd Elektrotechniczny, nr 1, 2005, str. 72-75.

[2] A. Duraj, A. Krawczyk, Zastosowanie sieci falkowo – neuronowej do detekcji zespołu QRS, Materiały XIV Krajowej Konferencji Naukowej „Biocybernetyka i Inżynieria Biomedyczna”, tom II, 21-23 Września 2005, str. 947-953.

[3] A. Duraj, A. Krawczyk, M. Kumor, Detekcja zespołu QRS przy zastosowaniu sieci falkowo – neuronowej, Przegląd Elektrotechniczny, nr 12, 2005, str. 98-100.

[4] A. Duraj, A. Krawczyk, E. Koźluk, M. Kumor, J. Sadowski, The Application of Wavelet Transforms to Detection and Identification of QRS, Folia Cardiologica, tom 12, Supp. D, 2005, pp. 390 - 392.

[5] A. Duraj, A. Krawczyk, M. Kumor, Detection and identification by means of wavelet technique, The Third Slovenian – Polish Joint Seminar on Computational and Applied Electromagnetics, June 6 – 8, 2005, Maribor, Slovenia, pp. 54 – 55.


[6] A. Duraj, A. Krawczyk, QRS detection by use of wavelet – neural networks, Przegląd Elektrotechniczny, nr 5, 2006, str. 54-56.

[7] MIT-BIH (http://ecg.mit.edu). [8] T. Master, Sieci neuronowe w praktyce. Programowanie w języku C++, Warszawa 1996. [9] S. Osowski, Sieci neuronowe w ujęciu algorytmicznym, Wydawnictwo Naukowo Techniczne

Warszawa 1996. [10] M. Kearns, A bound of terror of cross – validation Rusing the approximation and estimation ratek,

with consequences for the training – test split, Neural Computation, 1997, Vol. 9, pp. 1143 – 1161.


Neurophysiological Investigations of Retina’s Function and Evoked Activity

of Central Visual Structures under Microwave Irradiation

E. N. PANAKHOVA, T. M. AGAYEV, A. A. MEKHDIYEV, A. A. SADIYEVA

Institute of Physiology, Azerbaijan National Academy of Sciences [email protected]

Abstract.. The effects of decimeter microwaves (irradiation 460 MHz with output power 60 MW, duration 20 min) on functions of the visual system structures: retina, visual cortex and colliculus superior - under the conditions of formation of the focus of increased excitability in the amygdala and hypothalamus were studied. Transformation of patterns of responses in the retina, visual cortex and colliculus superior, being expressed in the most prominent way in the retina, evoked by photostimulus presentation, was shown. The clinical observations (duration: 30 days) revealed aggravation of general status. Immediately after irradiation exposure all studied rabbits showed transient signs of the first stage of kindling by the R.Racine scale; very often seizure jerking movements of limbs was observed. Besides, interictal spikes were registered electrographically.

Key words. retina, visual cortex, colliculus superior, decimeter microwaves.

Introduction

Intensification of technogenic factors exerts more and more significant impact on environment and as a result all living organisms are subjected to increased impact of the microwaves of wide range of frequency and power. Unequivocal reactions of the organism to the said impact may be expressed both in positive effect and in harmful toxic impact on the biological objects in the form of damaging factors. Particularly, toxic impact is revealed in their absorption by bio-objects under big power without relation to frequency values.

Presently, significant amount of data concerning effect of electromagnetic irradiation is collected, and the range of studies appears to be rather broad whereas the results are unequivocal. It has been shown that adverse impact of microwaves on different biological objects – from primitive bacteria in which gene mutations and modulations on genome level related to this effect, were noticed [1, 2], changes of biophysical indexes [3- 10, 13, 16, 17], studies on different laboratory animals [2, 5, 6,11,12, 13,14] including fundamental studies related directly to the human’s health beginning from children’s age [15, 16] – indicate to harmful impact of microwaves leading to stress formation [18, 19], neurological and oncological diseases [17, 20]. Particularly significant changes are observed in the central nervous system resulting in



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disturbances in memory formation, influencing negatively on sensory organs. Particularly, on acoustic system [12, 14], vision [5, 6, 10, 14, 15, 18], sleeping and cognitive functions [1, 4, 5, 7, 8, 15, 16, 17, 18, 19, 20, 21].

There are reliable evidences concerning impact of decimetric range of electromagnetic irradiation on nervous system and different portions of eyes including retina whose underlying mechanism correlates with intensification of lipids peroxidation leading to forthcoming destabililizing and thereafter destruction of biological membranes [11].

As well known, irradiation in the range of 280-292 nm is the most dangerous for humans’ eyes. Eyes’ cornea absorbs completely the rays shorter than 390 nm bringing to formation of kerato-conjuctivitis with acute hyperemia, burning sensation, pain and blefarospasm. In experiments exposure to high doses of ultraviolet irradiation led to opacification complicated with cataracta formation.

Presently, all studied spectrum portions with wave length from several millimeters to one thousandth parts of angstrom are biologically active and can not only lead to functional disorders, but as well induce unrecoverable organic damages of eye tissues, including retina [3, 4, 5]. There are evidences concerning impact of decimeter range of electromagnetic irradiation on eye’s components including retina whose mechanism is linked to intensification of lipids peroxidation, which, as a rule, is accompanied with forthcoming destabilization and thereafter destruction of biological membranes [11].

In the light of the above said it appears to be important revealing of character of advent, sequence and dynamics of impact decimeter range of microwaves on perceptive functions of visual system’s structures taking for consideration formation of electroretinogram (ERG) and pulses of central structures – visual cortex and Colliculus Superior (CS) evoked by light flashes. The clinical observations of animals’ physical state during one month from the first to the last day of experiment were used as supplement to electrophysiological studies.

Methods

The experiments were conducted on 50 alert rabbits of Grey Shinshilla species. ERG registration was accomplished by application of lens made from organic glass with implanted steel electrode. The eyes were etherized by installation of 25% solution of lidokain into conjunctiva sack. The tentative registrations of ERG of the left eye of naive rabbits were used as a control. Thereafter the animals were made free from all outcoming electrodes and subjected left eye to irradiation with application of special source of irradiation – therapeutic apparatus “Volna-2” – under frequency of decimeter irradiation of 460 MHz with output power of 60 mW. Daily exposure duration of irradiation was 20 min with total duration of 30 days. Simultaneously after irradiation ERG registration of the irradiated eye and evoked potentials from Visual Cortex and CS were initiated. The electrodes designed for registration of electrical activities and stimulation of visual nerves, were inserted into the corresponding brain structures (Amygdala, Hypothalamusand CS), according to stereotaxic coordinates by Marshall and Fifkova. After finishing neurophysiological studies, biochemical analysis of eye and mentioned brain structures was conducted.

All experimental procedures conform with the European Community guiding principles in the care and use of animals (86/609/CEE, CE Off J no. L 358, 18 December 1986) and were approved by the Institutional Animal Care and Use

E.N. Panakhova et al. / Neurophysiological Investigations of Retina’s Function 87

Committees at the Institute of Physiology and were conducted in accordance with the Azerbaijan Physiological Society’s ‘Guiding Principles in the Care and Use of Animals’. Killing of animals used in this study followed principles of good laboratory animal care and experimentation in compliance with Azerbaijan national laws and regulations. The rabbits were killed humanely by exposure to a rising concentrations of Nembutal.

Results and Discussion

Impact of non-ionizing irradiation on dynamics of development and character of modulations of ERG and EP patterns in response to presentation of photostimuli with intensity of 1.4 J was studied. The results showed that after irradiation significant variations of patterns of retina and brain structures are fixed. That was revealed in prominent (up to 80-100%) enhancement of generation of “b”-wave on ERG reaching values of 180-200 mkV, whereas control values were in the range of 100 mkV. The amplitude indexes of “a”-wave decreased to extremely low values – approximately 10 mkV, which constituted just 15-20% relatively to the original data (70 mkV). The analysis of such type of modulations showed that irradiation impact is revealed in elimination of inhibitory impact on retina from the visual cortex and as a result to sharp enhancement of “b”wave and inhibition of “a”-wave on ERG (Fig.1). To much more significant changes undergoes “c”-wave, whose amplitude reached 50-60 mkV.

Fig.1. Electroretinogram before (a) and after (b, c) irradiation.

Enhancement of generation of this ERG component indicates to modulation of metabolic processes in visual purple towards their increase both in conditions of presence of two loci of increased excitability (in amygdala and middle hypothalamus), and before their formation in the experiment (Fig.2). As it has been known, “c”-wave does not participate in the process of transduction and processing of visual signal realized in the retina. It is an index of dynamic metabolism in the visual pigment [3, 5, 6].

E.N. Panakhova et al. / Neurophysiological Investigations of Retina’s Function88

Fig.2. Impact of Amygdala stimulation on Retinogram generation (under strychnin application to Hipothalamus) under microwave irradiation. Designation: ”c”-wave is shown by the frame I – “a”-wave; II - “b”-wave; III- “c”-wave: mkV, ms

Simultaneously registration of EV in Visual Cortex and CS was conducted. It was revealed that irradiation effect originally is accompanied with significant inhibition of the first-order and secondary positive components (by 40-50% and 100-200%, correspondently) with simultaneous enhancement of formation of the first-order and secondary negativity by 45-50%.

Biochemical studies revealed opacification of the lens as well as revealed that in the retina of irradiated eye activation of both processes of lipids peroxidation (LPO) in the form of LPO products – malone dialdehyde (MDA) by over 1.3 times and hydroperoxides (HP) by over 1.35 times, and antioxidative enzymes – glutathione peroxidase (GP) – by 43% and superoxidismutase (SOD) – by 65%. Particularly, in the retina of right eye slight changes of LPO level (MDA – 1.3 times) is accompanied with decrease of HP (-50%) and slight increase of SOD (+25%). Probably, sharp reaction of the retina of the left eye in comparison is explained by direct impact of microwaves on the left eye (protective function of HP is, apparently, diminishes). In hypothalamus significant increase of LPO intensity (1.3-1.4 times) was shown which is accompanied with decreased activity of antioxidant enzymes (+1.2-1.3 times). In the Amygdala intensification of LPO (MDA – 1.2-1.6 times; HP – 1.3-1.5 times) was noticed. All above said correlate strictly with the results of electrophysiological studies which showed decreasing of amplitude parameters of responses of the central brain structures of the visual system and, particularly retina, in the last stage of experiments (after 30 days since the first irradiation). So, microwaves of decimeter range increasing oxidative processes, exert mostly negative impact on subcortical and central brain structures.

The clinical observations showed that microwave irradiation is accompanied with loosing weight by animal, anxious behavior, refuse from food intake (in single cases – with preterm death) as well as with gnashing with teeth ,advent of chewing movements and contraction of facial muscles which showed to the first stage of kindling over the adopted scale R.Racine [22].

Summarizing the obtained data, it should be emphasized that anxious changes observed in the all visual system structures in the first 7 days of experiment, bear reversible character and can be utilized in clinical practice as preventive measures to avoid ongoing organic disturbances (which were noticed on the last stage of our studies).


In conclusion, we express our deep gratitude to the collaborators of the Department of Biophysics of Cellular Metabolism (Head – Prof. A. Gadzhiyev) for carrying out biochemical analysis.

References

[1] S. Koyama, Y. Takashima, T. Sakurai, Y. Suzuki, M. Taki, Effects of 2.45 GHz electromagnetic fields with a wide range of SARS on bacterial and HPRT gene mutations, Lournal Radiat. Research (Tokyo), Vol. 48(1), pp. 69-75, 2007.

[2] S. S. Qutob, V. Chauhan, P. V. Bellier, C. L. Yauk, G. R. Douglas, L. Berndt, A. Williams, G. B.Gaida, Microarray gene expression proofing of a human glioblastoma cell line exposed in vitro to a 1.9 GHz pulse-modulated radiofrequency field, J. Radiet. Research, Vol. 165(6), pp. 636-644, 2006.

[3] A. V. Musayev, L. F. Ismailova, A. M.Gadzhiev, Effects of decimetric microvawes on thiol defense system in visual structures on animals of different age, Journal Fizioterapiya Balneologiya Reabilitaciya, Vol.6, pp. 13-17, 2005.

[4] A. V. Musaev, L. F. Ismailova, A. B. Shabanova, A. A. Magarramov, E. Yu. Yusifov, A. M. Gadzhiev, Pro- and antioxidant effect of Therapeutic microvawe irradiation (460 MHz) on Brain tissues in experiment, Journal Fizioterapiya Balneologiya REABILITACIYA, Vol.10(2), pp. 19-23, 2004.

[5] E. N. Panakhova, A. A. Sadiyeva, The neurophysiological investigations of Amygdalar and Hypothalamic influences on Retina’s and Central Visual structures perception function (by irradiation), Proceedings of Azerbaijan National Academy of Sciences, Vol. 5-6, pp. 132-144, 2005.

[6] E. N. Panakhova, A. A. Sadiyeva, Amygdalar and Hypothalamic influences on function of Retina and other structures of Visual System (in microwave irradiation conditions), Proceedings of Azerbaijan National Academy of Sciences, Vol. 1-2, pp.66- 75, 2006.

[7] M. H. Gaber, E. I. Abd, N. Halim, W. A. Khali, Effect of microwave radiation on the biophysical properties of liposomes, Bioelectromagnetics, Vol. 26 (3), pp. 194-200, 2005.

[8] H. Virtanen, J. Keshvari, R. Lappalaine, The effect of autothentic metallic implants on the SAR distribution of the head exposed to 900, 1800 and 2450 MHz dipole near field, Phys. Med. Biol., Vol. 52(5), pp.1221-1236, 2007.

[9] S. Koyama, Y. Isozumi, M. Taki, J. Miyakoshi, Effects of 45 GHz electromagnetic fields with a wide range of SARs on micronucleus formation in CHO-K1 cells, Scientific World Journal, Suppl. 2, pp. 29-40, 2004.

[10] C. Granfield, H. G. Wieser, A. L. Madan, J. Dobson, Preliminary evaluation of nanoscale biogenic magnetic-based ferromagnetic transduction mechanisms for mobile phone bioeffects, IEEE Trans. Nanobioscience, Vol.2 (1), pp. 40-43.

[11] A. I. Gadzhiev, E. Yu. Yusifov, M. T. Abbasova, L. F. Ismailova, A. B. Shabanova, J. M. Ibragimova, P. A. Khalilova, N. R. Bagirova, Study of microwave oxidative effect on organism, Proceedings of 3-rd Symposium of Azerbaijan Physiological Society, pp. 278-291, 2005.

[12] H. Virtanen, J. Keshvari, R. Lappalainen, The effect of autothentic metallic implants on the SAR distribution of the head exposed to 900, 1800 and 2450 MHz dipole near field, Phys. Med. Biol., Vol. 52(5), pp.1221-1236, 2007.

[13] J. Orendacova, M. Orendac, E. Racekova, J. Marsala., Neurobiological effects of microwave exposure: a review focused on morphological findings in experimental animals, J. Arch. Ital. Biol., Vol. 145 (1), pp.1-12, 2007.

[14] P. Galloni, G. A. Lovisolo, S. Mancini, M. Parazzini, R. Pinto et al, Effects of 900 MHz electromagnetic fields exposure on cochlear cell’s functionality in rats: evaluation on the biophysical properties of liposomes, Bioelectromagnetics, Vol. 26(3), pp. 194-200, 2005.

[15] E. van Rongen, E. W. Roubos, L. M. van Aernsbergen, G. Havenaar, F. B. Koops, F. E. van Leeuwen et al, Mobile phones and children: is precaution warranted? Bioelectromagnetics, Vol. 25 (2), pp.142-144, 2004

[16] L. Martens, Electromagnetic safety of children using wireless phones: a literature review, Bioelectromagnetics, Suppl. 7, pp. 1333-137.

[17] M. Kundi, K. Mild, L.Hardell, M. O. Mattsson, Mobile telephones cancer- a review of epidemiological evidence, J. Toxicol. Envirron. Health B. Crit Rev, Vol. 7(5), pp. 351-384, 2004.

[18] A. Bergamaschi, A. Margini, G. Ales, L. Copetta, G. Somma, Are Thyroid dysfunctions related to stress exposure (900 MHz)?, International Journal Immunopatholog. Pharmacology, Vol. 17(2), pp. 31-36, 2004.

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[19] H. B. Lim, G. G. Barker, L. A. Coulton, Effect of 900 MHz electromagnetic fields on non-thermal induction of heat-shock proteins in human leucocytes, Radiat. Research, Vol. 163 (1), pp. 45-52, 2005.

[20] H. P. Hutter, H. Noshammer, P. Wallner, M. Kundi, Subjective Symptoms, sleeping problems, and cognitive perforemance in subjects living near mobile phone base stations, J. Occup. Environ Med., Vol.63 (5), pp. 307-313, 2006.

[21] A. Besset, F. Espa, Y. Dauvilliers, M. Billiard, R. de Seze, No effect on cognitive function from daily mobile phone use, Bioelectromagnetics, Vol. 26 (2), pp. 102-108, 2005.

[22] R. J. Rasine, Modification of seizure activity by electrical stimulation, II. Motor seizures. Journal EEG Clinical Neurophysiology, Vol. 32, pp. 281-294, 1972


Mathematical Modelling of Vagus Nerve Stimulation

Bartosz SAWICKI a, Robert SZMURŁO a, Przemysław PŁONECKI a, Jacek STARZYŃSKI a, Stanisław WINCENCIAK a and Andrzej RYSZ b

a Warsaw University of Technology, Poland b Medical University of Warsaw, Poland

Abstract. This article presents a numerical model of a human vagus nerve stimulation therapy. The authors demonstrate methodology allowing to model both the direct electrical stimulator used for years in medical practice as well as the conceptual indirect magnetic stimulation used in computer experiments. The mathematical model of neural tissue excitation combined with a realistic 3D numerical model of the neck with the vagus nerve is described.

Keywords. Bioelectromagnetics, Eddy currents, Nerve stimulation

Introduction

The vagus nerve is one of the major elements of the peripheral nervous system. It starts in the stem of the brain and its branches extend to nearly the whole body. The vagus nerve is classified as one of the cranial nerves, emerging directly from the brain in contrast to spinal nerves which emerge from segments of the spinal cord. The vagus nerve provides a unique possibility to interact brain activity.

(a) (b)

Figure 1. (a) Vagus nerve location in the neck, (b) VNS device.

In Vagus Nerve Stimulation (VNS), an external excitation source is applied to the

vagus nerve. For about 10 years this technique has been used as a therapeutic tool for controlling seizures in epilepsy patients. Because the vagus nerve is associated with



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many different functions and brain regions, research is being done to determine its usefulness in treating other illnesses, including various anxiety disorders, Alzheimer's disease and migraines [9]. Recently VNS applications have been expanded to cover the treatment of another diseases such as drug-resistant cases of clinical depression.

1. Virtual neck

To perform any form of numerical modelling, creation of a virtual neck is required. The most popular source data for such models are obtained by MRI scans of the human body. For our vagus nerve model, a special series of MRI scans had been performed. Fig. 2 (a) presents only a few of the 40 slices used to create the 3D model. Each of them has a resolution 512x512 pixels. The slices were taken every 4 mm along the neck.

Every 2D slice/picture has been segmented to distinguish different human tissues. It had been decided to distinguish four different materials (bones, gullet, vagus nerve and the rest of body). This decision was justified by the values of the electrical conductivity of tissues. The segmented pictures were combined into a 3D model. This is suiteable for finite element calculations which means that it divides the volume with a mesh of 620,000 tetrahedra and 110,000 nodes.

In Fig. 2 (b) an internal structure of a completed numerical, virtual neck is visualised. One can notice a spinal column, a few teeth and the narrow contour of the vagus nerve.

(a) (b)

Figure 2. Virtual neck model; (a) set of MRI slices, (b) transparent view of final version of model.

2. Direct Electric Stimulation

The most commonly used method of a nerve stimulation, known for more than 100 years, is the current injection into the nerve fiber. Usually this is acquired by applying an electric voltage source with direct contact to the nerve. Such an approach is used in VNS. During a surgical operation the generator is implanted under the skin of the left chest and connected to electrodes fixed around the left vagus nerve. In Fig. 3, showing real electrodes, we can distinguish three components: the rightmost electrode with negative polarity, the middle electrode with positive polarity and an anchor which helps to fix the electrodes into place (on the left of the picture). To avoid tissue injury during

B. Sawicki et al. / Mathematical Modelling of Vagus Nerve Stimulation 93

the stimulation in the vicinity of the platinum electrodes they are embedded in the silicone helix. This is the major factor of high impedance seen by the generator. The stimulating device is regularly checked if the electrodes impedance is within the range of 1 to 8 kΩ [8]. If the impedance is outside of the range, this usually means that the device has failed.

To develop an excitation model we treat the nerve fiber as a bundle of axons. The response of each axon on the stimulus is specific, but in such a homogeneous medium like fiber we may assume that the behaviour is very similar. Thus we can average it. In our approach to VNS we combine the model of stimulation for a single axon with the model of the whole neck and nerve fiber.

Figure 3. Vagus nerve electrical stimulation: stimulator electrodes

We shall start with mathematical model for cell membrane of a single axon, and

later to combine it with model of whole fiber. During the activation of an axon, an evoked potential is generated in form of a

depolarization of neural cell membrane. The dynamics of the excitable cell membrane voltage in a specific point may be described by a system of ordinary differential equations. The most widespread is the Hodgkin-Huxley non-linear model which contains four state variables. Because we need to solve this model many times during the simulation (thousands times for each time step) we have chosen the simplified model proposed by FitzHugh.

(1)

where Is is a stimulating current which in our model is always 0, a=0.13, b=0.013, c1=0.26, c2=0.1, d=1.0 are the experimental coefficient propose by FitzHugh.

The most important variable in the membrane model is the membrane voltage Vm. The propagation of the neural impulse along the axon is equivalent to depolarization travelling along it. From the other point the membrane voltage allows us to combine the mathematical description of the interiors and exteriors of neurons. The electric field outside the cells and the field inside of cells can be described by scalar electric potentials. To calculate each of those potentials we need the governing equation and boundary conditions. The governing equation emerges from charge conservation law, which constrains the divergence of current density at each point. Coupling these constrains for extra- and intracellular regions we end with two partial differential equations [1]:

(2)

B. Sawicki et al. / Mathematical Modelling of Vagus Nerve Stimulation94

where eΦ and iΦ are the extracellular and intracellular potentials, Iion is the ionic current passing the membrane evaluated from the FitzHugh model χ parameter maps surface currents of the cell membranes to the volume currents of the macromodel and thus allows to average the discrete ionic currents evaluated in a single point onto the volume quantity. χ represents the membrane area contained in the volume unit. Thus the Iion multiplied by the χ factor represents all cumulative current passing all membranes in the unit volume.

The electrical stimulation is put in the extracellular domain using the Dirichlet boundary conditions for eΦ in the place where electrodes have contact with nerve bundle. To simulate the silicone isolating layer around the electrodes we have decreased the potential of the conditions. The location of the Dirichlet boundary condition was choose with electrodes configuration, as shown on Fig. 3. The energy provided to the system by the boundary condition in eΦ domain propagates to the iΦ domain and causes the current flow through the membrane, thus stimulates the neuron. The activation may be observed in the solution of the FitzHugh ordinary differential system.

We have solved the problem using self developed computer software. The simulation length was 6 ms with 0.01 ms time step. The nerve was stimulated by a single bell shaped impulse with length of 1 ms Propagation of the excitation in nerve was observed. Validation of biomedical models is a challenging task. Any direct measurements inside the real human body is trouble some because of many aspects. The mathematical model presented in this paper was validated be comparison of the speed of propagation of the action potential obtained from simulation (32 m/s) with the experimental measurements (45 m/s) [3]. The comparison showed a pretty good agreement of both simulated and experimental values. Difference can be simply decreased by changing constant parameters used in equations (1) and (2).

3. Indirect Magnetic Excitation

For many years scientists have been attempting to replace the direct electric stimulation by a magnetic one. It is expected that similar effects can be obtained using magnetic stimulation, which could be non-invasive and less onerous for patients. The most known example is the transcranial magnetic stimulation (TMS) which ought to be a replacement for electroconvulsive therapy (ECT).

The biological background of electric and magnetic field stimulation is the same. External time-varying magnetic fields excite eddy currents inside the body. Density of eddy currents is in direct relation to electric field density, so it stimulates neural tissue.

The first step of simulation is to compute the distribution of magnetic fields generated by an exciting coil. Assuming constant magnetic permeability this can be done by simple integration according to the Biot-Savarte law:

(3)

where sJr

is current density inside the source coil. The eddy current phenomena in low conducting media can be described by partially


differential equation [5, 7]:

(4)

We will omit here discussion about variants of implementation of (4). It is enough to know that such equation can be solved efficiently even for very complicated models. Only 10 minutes of calculations were needed to find a solution on our 2 GHz computer.

(a) (b)

Figure 4. Indirect magnetic stimulation, (a) location of the exciting coil, (b) eddy currents density in the cross section of the model (vagus nerve mark with right black line spot).

Results in the form of eddy currents density magnitude is presented on Fig. 4 (b). The vagus nerve marked with a black line on the right is under influence of the coil field. The values of the current density are often used as a criteria for neural tissue excitation, in such a case we finish the process of simulation at this point.

The authors see the possibility to join passive results of magnetic stimulation with a realistic model of neuron excitation presented in the previous section. Eddy current density distribution should be applied as an excitement source. The mathematical model of such complicated interaction is under heavy development, the following works will contain new details.

4. Conclusions

This methodology presented by the authors can be used for the simulation of nerve stimulation excited both by electric and magnetic fields. The model of electric excitation of neurons has been implemented using a bidomain approach. Validation of the method using action potential propagation speed produces a positive result. A magnetic stimulation described as an eddy currents phenomena was modelled. Vagus nerve stimulation is young therapy, so it is not surprising that there is a lack of its modelling methods. Apart from a mathematical descriptions we also need trustworthy methods for validating numerical models with biological reality. The validation is probably the most difficult part of the problem. This research was supported by the Polish Ministry of Science and Higher Education under

Grant No. N510 030 31/1379.

B. Sawicki et al. / Mathematical Modelling of Vagus Nerve Stimulation96

References

[1] R. Szmurło, J. Starzyński, B. Sawicki, S. Wincenciak, A. Cichocki, Bidomain Formulation for Modeling Brain Activity Propagation. IEEE Conference on Electromagnetic Field Computation (CEFC), USA, 2006, pp. 345.

[2] Wulfram Gerstner and Werner Kistler, Spiking Neuron Models: Single Neurons, Populations, Plasticity, Cambridge University Press, 2005.

[3] Hermann M. , Freissmuth M ., Neuromonitoring of the Recurrent Nerve: Validation and Merits. Journal European Surgery, October 2003, vol. 35, no. 5, pp. 228-235.

[4] P. M. Santos: Surgical placement of the vagus nerve stimulator, Operative Techniques in Otolaryngology (2004) 15, 201-209

[5] W. Wang, S. R. Eisenberg, A Three-Dimensional Finite Element Method for Computing Magnetically Induced Currents in Tissues, IEEE Transactions on Magnetics, vol. 30, no. 6, pp. 5015-5023, Nov. 1994.

[6] N. Siauve, R. Scorretti, N. Burais, L. Nicolas, A. Nicolas,: Electromagnetic fields and human body: a new challange for the electromagnetic field computation, COMPEL, Vol. 22 No. 3, 2003.

[7] B. Sawicki, P. Płonecki, J. Starzyński, S. Wincenciak, The Quest for the Best Potential for Biomedical Eddy Currents Problems, Proceedings of COMPUMAG, Aachen, Gernamy, June 2007.

[8] Physician’s Manual, VNS Therapy Pulse Model 102 Generator and VNS Therapy Pulse Duo Model 102R Generator 0.1, Part II – Technical Information—VNS Therapy Pulse Model 102 Generator and Pulse Duo Model 102R Generator.

[9] D. A. Groves, V. J. Brown, Vagal nerve stimulation: a review of its applications and potential mechanisms that mediate its clinical effects.. Neuroscience and Biobehavioral Reviews, 29, pp. 493-500, 2005.


Immunotropic Influence of Low Dose Ionizing Irradiation and Microwaves

Applied Sequentially on Human Blood Mononuclear Cells in vitro

W. STANKIEWICZ, M. P. DĄBROWSKI, A. CHEDA1,E. NOWOSIELSKA1, J. WREMBEL-WARGOCKA1, R. KUBACKI, M. JANIAK1 , S. SZMIGIELSKI

Military Institute of Hygiene and Epidemiology, Dept. of Microwave Safety and 1Dept. of Radiobiology and Radiation Protection,

Warsaw, Poland. E-mail : [email protected]

Abstract. Human blood mononuclear cells (PBMC) were exposed to X-rays 0,1 Gy, to Microwaves 2850 MHz, SAR 0,1 W/kg or to the both exposures sequentially. In the microculture system functional properties of T lymphocytes and monocytes were tested and production of monokines (IL-1β, IL-1ra) was estimated. The irradiation protocols influenced differentially T cell response to mitogens (PHA, Con A), degree of saturation of IL-2 receptors, immunoregulatory T cell suppressive avtivity, monocyte immunogenic activity and monokine production. The administered irradiations have demonstrated immunotropic influence modulating the both T lymphocyte immunocompetent functions and monocyte immunogenic activity.

Keywords. Microwaves, low dose ionizing irradiation, human immune cells, immunoregulation

Introduction

The energy of electromagnetic fields of the both ionizing radiation (IR) and microwaves (MW) nature, may influence many functions of living organisms. Recent development and common use of different low energy and high frequency MW emitters (mobile phones, radar and microwave broadcast stations) and sources of IR, increased the interest on the risk of their possible harmful influence, and, on the other hand, on the potential of their therapeutic application.

The undisturbed defensive, tolerogenic and proregenerative activities of immune system are essential for the proper functioning of homeostatic mechanisms of the organism. Thus, basic immunoregulatory activities which can be observed and precisely quantified in microcultures of immune cells separated from the human blood, represent an unique and objective model for investigation of possible immunotropic effects of defined IR and MW.

The aim of our investigation was to determine the possible immunotropic influence of low dose of IR and MW administered separately or sequentially, on chosen



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parameters characterizing immunoregulatory properties of mononuclear cells (lymphocytes and monocytes) isolated from the human blood and cultured in vitro.

Material and Methods

The samples of mononuclear cells (PBMC) from healthy donors (N = 20) were irradiated with X-rays in a dose of 0.1 Gy, exposed to MW (2850 MHz, pulse modulated, SAR 0,1 W/kg) or exposed sequentially to both irradiations. The control samples were left without irradiation. After determination of cell viability the microcultures of PBMC were set up in triplicate, each containing 105 viable cells in 0.2 ml of RPMI 1640 supplemented with 15% of inactivated autologous serum and incubated for 72 hours at 37oC in an ASSAB CO2 (5%) incubator as described earlier [1, 2, 3]. The following parameters of T cell and monocyte activity were determined after harvesting the cultures: (a) spontaneous 3HTdR incorporation, (b) T cell response to PHA, (c) T cell response to Con A, (d) suppressive activity of T cells (SAT index), (e) saturation of IL-2 lymphocyte receptors (IL-2 index) and (f) monokine (IL-1β/IL-1 ra) influence on lymphocyte proliferative response (LM index). Concomitantly, the PBMC microculture supernatants collected at 24 h from the separate sets of not stimulated with mitogen microcultures, were assessed for the concentration of chosen cytokines (IL-1β, IL-1ra, IL-10) by ELISA method with the use of respective cytokine kits (R&D, Mineapolis, USA).

Results

The PBMC representing low response to mitogens (control response to PHA ≤ 45x103 dpm/cult., to Con A ≤ 30x103 dpm/cult.) were not sensitive for separate or sequential irradiation with IR and MW (Table 1). The low values of IL-2 receptor saturation and T cell suppressive activity (SAT) increased significantly under influence of the all protocols of ionizing (IR) and microwave (MW) irradiation. Concomitantly to that, the IL-10 concentrations also increased in these cultures (result not shown in the table).

The PBMC responding to PHA at the normal level (> 45x103 dpm/cult.) were sensitive to irradiations and the all protocols significantly decreased the response (Table 2). Normal response to Con A and normal level of saturation of IL-2 receptors did not change under effects of irradiations. Only exposure to MW decreased normal SAT value but not if administered after irradiation with IR. Irradiation with IR, with IR+MW but not with MW decreased significantly saturation of IL-2 receptors in PBMC which represented in control proper values of IL-2 receptor saturation. In those with lower than normal values of saturation of IL-2 receptors, IR, MW and IR+MW irradiations increased significantly values of saturation of IL-2 receptors.

W. Stankiewicz et al. / Immunotropic Influence of Low Dose Ionizing Irradiation 99

Table 1. Influence of X-rays irradiation, MW irradiation or sequential irradiations with X-rays and MW on T lymphocyte functional properties in the low responder’s PBMC populations (control response to PHA ≤ 45,0 dpm x 103/cult., to Con A ≤ 30,0, saturation of IL-2 R ≤ 80%, SAT index ≤ 20%)

Test control X-rays 0,1 Gy MW 2850 MHz X-rays + MW Response to PHA dpm x 103/cult

32,1 ± 7,9

28,2 ± 9,8

29,3 ± 6,3

27,5 ± 11,1

Response to Con A dpm x 103/cult

24,5 ± 5,1

23,4 ± 7,1

25,0 ± 6,1

23,2 ± 5,0

Saturation of IL-2 receptors %

77,1 ± 9,3

96,2 ± 7,2 * ↑

94,1 ± 10,1 * ↑

89,2 ± 8,9 * ↑

T-cell suppressive activity (SAT) %

15,2 ± 6,9

28,9 ± 14,0 * ↑

27,0 ± 11,2 * ↑

30,2 ± 9,8 * ↑

* statistical significance p < 0,05 Table 2. Influence of X-rays irradiation, Mw irradiation or sequential irradiations with X-rays and MW on T lymphocyte functional properties in high responder’s PBMC populations (control response to PHA > 45,0 dpm x 103/cult., to Con A > 30,0, saturation of IL-2 R > 80%, SAT index > 20%)

Test control X-rays 0,1 Gy MW 2850 MHz X-rays + MW Response to PHA dpm x 103/cult

62,3 ± 17,1

54,2 ± 14,9 * ↓

53,3 ± 12,6 * ↓

44,9 ± 11,9 * ↓

Response to Con A dpm x 103/cult

40,1 ± 14,8

34,2 ± 14,1

42,3 ± 15,3

35,2 ± 13,2

Saturation of IL-2 receptors %

94,6 ± 5,0

87,1 ± 12,2

92,2 ± 9,1

90,1 ± 9,1

T-cell suppressive activity (SAT) %

33,8 ± 7,8

26,5 ± 8,8

14,8 ± 7,5 * ↓

26,5 ± 6,2

* statistical significance p < 0,05

PBMC representing low immunogrnic activity of monocytes (LM index ≤ 8,0) decreased this activity only under influence of sequential exposures to IR and MW (Table 3). Similarly, this protocol of exposures also decreased IL-1β production in PBMC populations demonstrating low level of the production of this monokine. The concentrations of IL-1ra did not change in these PBMC. The excessive immunogenic activity of PBMC, represented by LM values > 8,0 and IL-1β production > 250 pg/ml (Table 4), decreased significantly under influence of irradiation with X-rays (IR) but not under influence of exposure to MW. The concentration of IL-1ra did not change under influence of the all protocols of exposures.

Table 3. Influence of X-rays irradiation, MW irradiation or sequential irradiations with X-rays and MW on the monocyte functional properties in the PBMC populations representing low immunogenic activity (LM index ≤ 8,0, concentration of IL-1β ≤ 250 pg/ml, concentration of IL-1ra ≤ 1500 pg/ml)

Test control X-rays 0,1 Gy MW 2850 MHz X-rays + MW LM index 4,1 ± 2,5 2,9 ± 1,6 3,6 ± 3,1 2,8 ± 1,5 * ↓ Concentration of IL-1β pg/ml

165 ± 55 156 ± 74 175 ± 76 136 ± 78 * ↓

Concentration of IL-1ra pg/ml

877 ± 453

796 ± 720 854 ± 530 765 ± 743


W. Stankiewicz et al. / Immunotropic Influence of Low Dose Ionizing Irradiation100

Table 4. Influence of X-rays irradiation, MW irradiation or sequential irradiations with X-rays and MW on the monocyte functional properties in the PBMC populations representing high immunogenic activity (LM index > 8,0, concentration of IL-1β > 250 pg/ml, concentration of IL-1ra > 1500 pg/ml)

Test control X-rays 0,1 Gy MW 2850 MHz X-rays + MW LM index 15,5 ± 6,5 8,9 ± 4,5 * ↓ 12,5 ± 7,1 8,3 ± 5,1 * ↓ Concentration of IL-1β pg/ml

315 ± 65 231 ± 54 * ↓ 245 ± 76 * ↓ 236 ± 72 * ↓

Concentration of IL-1ra pg/ml

2035 ± 444

1580 ± 536 1910 ± 498 1763 ± 642


Conclusions

1. Low dose of ionizing irradiation (0,1 Gy) and low energy microwaves (2850 MHz, SAR 0,1W/kg) can modulate immunoregulatory abilities of T lymphocytes and monocytes in PBMC populations in vitro. 2. The IR exposure modulate beneficially the activity of immune cells increasing the low values of SAT (T cell suppressive activity), increasing also saturation of IL-2 receptors and decreasing excessive immunogenic activity of monocytes (LM index and production of IL-1β). 3. The MW exposure improved low values of saturation of IL-2 receptors and increased low values of T cell suppressive activity (SAT index) but decreased initially high values of SAT index. 4. The sequential IR+MF exposures have positively compensated the decreasing effects of MW on SAT values.

References

[1] M. P. Dąbrowski, B. K. Dąbrowska-Bernstein, A. Stasiak, K. Gajkowski, S. Korniluk, Immunological and clinical evaluation of multiple sclerosis patients treated with corticosteroids and/or thymic hormones, Annals N.Y. Acad. Sci. 496 (1987), 697–706.

[2] M. P. Dąbrowski, W. Stankiewicz, T. Płusa, A. Chciałowski, S. Szmigielski, Competition of Il-1 and IL-1ra determines lymphocyte response to delayed stimulation with PHA, Mediators of Inflammation 10 (2001), 101–107.

[3] W. Stankiewicz, M. P. Dąbrowski, R. Kubacki, E. Sobiczewska, S. Szmigielski, Immunotropic influence of 900 MHz microwave GSM signal on human blood immune cells activated in vitro, Electromagnetic Biol. Med. 25 (2006), 45–51.

W. Stankiewicz et al. / Immunotropic Influence of Low Dose Ionizing Irradiation 101

Chapter 3

Electromagnetic Field and Biology

Oxidative and Immune Response

in Experimental Exposure

to Electromagnetic Fields

Dana DABALA1

, Didi SURCEL2

, Csabo SZANTO2

, Simona MICLAUS3

,

Mariana BOTOC2

, S. TOADER2

, O. ROTARU2

Department of Occupational Medicine, Transport Regional Public Health Center,

Cluj- Napoca, Romania

Department of Occupational Medicine, Institute of Public Health, Cluj-Napoca, Romania

Land Forces Academy, Sibiu, Romania

Abstract. Although the physical techniques for measuring of the electromagnetic

fields (EMF) are well developed, adequate characterization of the biological

effects induced by EMF is subject of discussion yet. We don’t know the effects

that would be after a long term of exposure. Many scientific studies have been

devoted to assessing what health risks are associated with EMF exposure. Data

from the recent experiments suggest that EMF are associated with the iron-

mediated free radical generation, that can cause damage in the biologic molecules

such as lipids, proteins and can profoundly affect cellular homeostasis. The aim of

this study was to show the effects of the chronic exposure to EMF on the immune

and oxidative response. In vivo experiment was carried out on 80 Wistar rats that

were divided in 4 groups as following: 1. Control-group, without exposure,

sacrificed at 1 month; 2. Control-group, without exposure sacrificed at 3 months;

3. EMF–exposed group, sacrificed at 1 month; 4. EMF – exposed group, sacrificed

at 3 months. The rats were exposed to RF EMF that covers a range of the

frequencies between 140-160 MHz generated by a Motorola device. The

components of EMF field were measured with an EMF 200 Monitor

Wandel&Goltermann (the measured Power density (S) was 8+/- 1 W/m2

).The

following parameters were assessed : a) 3HTdR incorporation test; b) IL-1 assay;

c) TNF-assay; d) Chemiluminiscence assay; e) Lipid peroxides. The 3HTdR

incorporation was decreased in the EMF- exposed groups, as compared with

control groups, but with statistically significant difference (ssd) (p>0.01 ) only in

third group. Increased values of the cytokines ( IL-1 and TNF ) were found in the

3 and 4 – groups, with ssd for both of the cytokines (p> 0.05 for IL-1 and p> 0.01

for TNF) Chemiluminescence assay and lipid peroxides were parameters with

increased values for 3 and 4 groups, but ssd were found only in the forth -group.

Our results point out an important increased of the oxidative response in the EMF-

exposed groups, in special in the group sacrificed at 3 months. In the forth group,

an important suppression of the immune response and increased activity of the

cytokines was demonstrated. Our results indicate an association between

electromagnetic fields and immune and oxidative response, suggesting increased

modifications in the group with EMF -prolonged exposure.

Keywords. the effects of the chronic exposure to EMF on the immune and

oxidative response.

1

2

3


105

1. Introduction

Although the physical techniques for measuring EMF are well developed, adequate

characterization of the biological effects induced by EMF is subject of discussion yet.

We don’t know the effects that would be after a long term of exposure. Many scientific

studies have been devoted to assessing what health risks are associated with EMF

exposure. Data from the recent experiments suggest that EMF are associated with the

iron-mediated free radical generation, that can cause damage in the biologic molecules

such as lipids, proteins and can profoundly affect cellular homeostasis.

2. Materials and Methods

In vivo experiment was carried out on 80 Wistar rats that were divided in 4 groups as

following: 1. Control-group, without exposure, sacrificed at 1 month, 2. Control-group,

without exposure sacrificed at 3 months, 3. EMF–exposed group, sacrificed at 1 month,

4. EMF – exposed group, sacrificed at 3 months.

The rats were exposed 4 hours/day to RF EMF that covers a range of the frequencies

between 140-160 MHz generated by a Motorola device. The components of EMF field

were measured with an EMF 200 Monitor Wandel&Goltermann (the measured Power

density (S) was 8+/- 1 W/m2

).

The following parameters were assessed: a) 3HTdR incorporation test, b) IL-1 assay,

c) TNF-assay, d) Chemiluminiscence assay, e) Lipid peroxides.

Fig. 0. Materials and methods

EMF :

Freq= 160 MHz;

S ech= 8+/-1Wm2

Motorola

Wistar rats CONTROLS (20)

Wistar rats

EXPOSED GROUP (20), 4hours/day

PARAMETERS

• 3HTd-incorporation test

• IL-1 assay

• TNF-assay

• Chemiluminiscence assay

• Morphopatological exam

SSAACCRRIIFFIICCEEDD AAFFTTEERR 11 aanndd 33 MMOONNTTHHSS

TISSUES

SPLEEN

AM

BBAALL

D. Dabala et al. / Oxidative and Immune Response in Experimental Exposure to EMF106

17800 18300

15120

9780

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

cpm

groups

C1

C2

EMF1

EMF2

17800 18300

15120

9780

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

cpm

groups

C1

C2

EMF1

EMF2

3. Results

The 3HTdR incorporation was decreased in the EMF-exposed groups, as compared

with control groups, but with statistically significant difference (ssd) (p>0.01 ) only in

third group. Increased values of the cytokines ( IL-1 and TNF ) were found in the 3 and

4 – groups, with ssd for both of the cytokines (p> 0.05 for IL-1 and p> 0.01 for TNF).

Chemiluminescence assay and lipid peroxides were parameters with increased values

for 3 and 4 groups, but ssd were found only in the forth -group. Our results point out an

important increased of the oxidative response in the EMF- exposed groups, in special

in the group sacrificed at 3 months. In the forth group, an important suppression of the

immune response and increased activity of the cytokines was demonstrated.

Our results point out the following:

an important increased of the oxidative response in the EMF- exposed groups,

in special in the group sacrificed at 3 months.

an important suppression of the immune response

increased activity of the cytokines in all the groups exposed to EMF

Fig.1.3

HTdR INCORPORATION TEST Effect of the chronic exposure to EMF on the 3HTdR

incorporation by PHA splenic Lys in the presence of the autologous AMs , at 30 and 90 days after

EMF – exposure of the rats

Fig. 2. IL-1 assay Effect of on the chronic exposure to EMF on the IL-1 release by AMs obtained by BAL,

30 and 90 days after EMF – exposure of the rats.

D. Dabala et al. / Oxidative and Immune Response in Experimental Exposure to EMF 107

248

310

815

1760

0

200

400

600

800

1000

1200

1400

1600

1800

cpm

groups

C1

C2

EMF1

EMF2

110

190

380

730

0

100

200

300

400

500

600

700

800

nMol

groups

C1

C2

EMF1

EMF2

Fig. 3. TNF- assay Effect of the chronic exposure to EMF on the TNF release by rats AMs, obtained by

BAL, 30 and 90 days after EMF – exposure of the rats.

Fig. 4. LUMINOL -DEPENDENT CHEMILUMINISCENCE ASSAY. Effect of the chronic exposure to

EMF on ROS release from the rats AMs, obtained by BAL, 30 and 90 days after EMF – exposured rats.

Fig. 5. LIPID PEROXIDES ASSAY Effect of the chronic exposure to EMF on the release of the LP in the

TBA- treated AMs, at 30 and 90 days after EMF – exposured rats.

235320

2100

4500

0

500

1000

1500

2000

2500

3000

3500

4000

4500

cpm

groups

C1

C2

EMF1

EMF2

D. Dabala et al. / Oxidative and Immune Response in Experimental Exposure to EMF108

4. Conclusions

Although important issue are not yet resolved in this study, our results showed that

EMFs caused changes in the immune system, possible mediated by the proliferative

response of the T cells, by their distribution and by the cytokines ‘activity. Our

results clearly show that the exposure to EMF is connected to an increased release of

free radicals. The increased levels of the ROS pointed out alterations in the oxidative

stress parameters in the rat’s macrophages that were exposed to EMF. Our results

indicate an increased risk regarding development of the biological effects in EMF

exposure correlated with intensity and period of the exposure.

References

[1] Becker R. O., Marino A. A., Electromagnetic pollution, The Sciences, January, 1978, pp 14, 15, 23

[2] Bell G.B., Marino A.A., Chesson A.L- Human sensitivity to weak magnetic fields, Lancet 338: 1521-

1522, 1991

[3] Bell G.B., Marino A.A., Chesson A.L.- Frequency –specific responses in the human brain caused by

EMF , J. Neurol.Sci. 123:26-32, 1994

[4] Bajinyan S, Hovhannisyan N., Arakelyan V. – The Effect of Millimeter-range Electromagnetic

Waves of Low Intensity on Cellular Membranes, Effect of Electromagnetic Waves on Cellular

Membranes 1999, 5(1):43- 49

[5] Gianni M., Maggio F., Liberti M, Paffi A- Modeling Biological Noise in Firing and Bursting Neurons

in the Presence of an EMF-Proceedings of the 2-the International IEEE EMBSArington, Virginia,

2005

[6] Kelsh M.A., Bracken T.D., Sahl J.D., Shum M., Ebi Kl.- occupat. Magnetic field exposure of garment

workers- Bioelectromagnetics, 2003; 24(5): 316 -26

[7 Kjell Hansson Mild, Mike Rapacholi, Emilie van Deventer, Paolo Ravazzani - EMF Hypersensitivity,

Proceedings of the International Workshop on EMF Hypersensitivity, Prague, Oct.25-27, 2004

[8] Leif G. Salford, Arne E. Brun, Jacob L. Eberhardt, Lars Malmgren , Bertil R. R. Persson-Nerve Cell

Damage in Mammalian Brain after Exposure to Microwaves from GSM Mobile Phones-Environmental

Health Perspectives,vol.111, number7, June 2003

[9] Henry Lai, Narendra P. Singh-Magnetic-Field-Induced DNA Strand Breaks in Brain Cells of the Rat-

Environmental Health Perspectives,vol 112, number 6, May 2004

[10] Lantow M., Lupke E.M., Frahm E.J., Mattsson E.M.O. - ROS release and Hsp70 expresion

afterexposure to1,800 MHzRMF in primary human monocytes and lympocytes- Radiat.

Environ.Biophys, 2006

[11] Marino A.A, Marcel Dekker, Environ. EMF and public health, New York, 965- 1044, 1988

[12] Marino A.A, Morris D.M., Chronic electromagnetic stressors in the environment : A risk factor in

human cancer, J. Environ. Sci.C3(2) 189- 219,1985

[13] Mailhes J.B., Young D, Marino A.A – Mutagenesis, 12:347- 351,1997

[14] Repacholi M.H. – Low –Level Exposure to Radiofrequency Electromagnetic Fields,

Bioelectromagnetics 19: 1-19, 1988

[15] Santini R., Santini P, Le Ruz P., Danze-Survey study of people living in the vicinity of cellular phone

base stations. Electromagnetic biology and Medicine, 2003;22, 41- 49

[16] Zhang J.,The effect of low force chiropractic adjustments on body surface EMF- J. Can. Chiropr.

Assoc.2004; 48(1).

D. Dabala et al. / Oxidative and Immune Response in Experimental Exposure to EMF 109

Acoustic/Magnetic Field Assisted

Perfusion Study

A.H.J. FLEMING, E. B. BAUER, R. BERGERON, M. DAHLE, J. ENGE

Biophotonics Research Institute, Australia. [email protected]

Abstract. This pilot investigation assessed the effectiveness of a vibrating acoustic

device combined with a system of structurally imbedded permanent magnets to

increase perfusion in areas of application. The device, a Cyma 1000, delivered five

acoustic frequencies 900- 1300 Hz chosen for arterial support. The permanent

magnet was built into the face of the applicator and oscillated at the same

frequencies as the generated acoustic wave. A control group was chosen having

normal perfusive ability, a second group was chosen to test the applicator's ability

to assist perfusion across a range of pathological conditions. Thermography was

used to view perfusion before and after application. Both groups and all cases

studied showed application improved perfusion.

1. Introduction

Blood supply is vital to the viability of healthy cells, tissues, and organs and is essential

for sustaining life. The function of the circulatory system is to deliver oxygen and

nutrients to cells and to remove carbon dioxide and waste products for the purpose of

maintaining tissue pH. Without perfusion, organ systems suffer; the process of

ischemic cascade and cellular degradation ensues, and life ends. When perfusion is

impeded, eschemic cascade ensues within seconds to minutes, necrosis due to ischemia

usually ensues after about 10-12 hours.[1-3]. Over the past decade a number of studies

have been performed to investigate the therapeutic use of magnetic fields to mitigate

against ischemic cascade while it is occuring and to repair tissues damaged following

reperfusion [4-6]. A biological mechanism behind the efficacy of the magentic field in

these cases may lie in recent mathematical developments in understanding the self

fields of atoms [7-8]. Self field theory gives actual dynamics of the sub-atomic

particles in contrast to the probabilistic results of quantum mechanics. When a

magnetic field is applied, an outer shell electron inside the atom does not change its

orbital speed but rather its cyclotron speed, its spin, is increased. Like the gyroscopic

ability well-known in ballistic design to keep projectiles on track and thus increase

their effective range, the magnetic field may increase the ability of ions, and other

blood-borne components to ward off unwanted randomly directed electric fields in the

arterial milieu due to the reactions invovled in ischemic cascade.

As for the acoustic fields, Bauer and Fleming have previously presented results

from another pilot study using the Cyma 1000's acoustic fields without the dynamic

magnetic field to promote repair of a tendon in a thoroughbred racehorse [9]. It is

known that an acoustic field can vibrate DNA and a frequency can be calculated for

these vibratory modes [10]. The 'Code 129 Artery Support' has been designed to

improve peripheral perfusion. This code as well as all of the codes in the Cyma 1000 is



110

a combination of five frequencies called a commutation. The five frequencies range

from 900 to 1300 Hz [11]. The preliminary investigation, using thermography as an

indicator, aimed to examine the value of applying frequencies specific to supporting

increased arterial flow to areas of the body with the acoustic/magnetic applicator.

2. Method

After obtaining and reviewing a detailed medical health history and a medical

examination; a random control group of 10 subjects, aged 25 to 65, without underlying

vascular pathology, was selected. Baseline thermographs were obtained before any

intervention. After evaluating the baseline thermographs, the hand-held acoustic device

(Cyma 1000) was used to deliver specific audible frequencies that ranged from 900 to

1300 Hz. The applicator had 8 x 2000G magnets imbedded on its face which was held

next to the surface of the body. In the normal control group frequencies were

administered for 10 minutes to both forearms in supination, an area from the wrist to

the elbow with palm side up. Following the successful results of the random control

group it was decided that a further experimental group showing vascular compromise

should be studied. The vascular-compromised experimental group studied included

those with pulmonary diseases and peripheral vascular disease. In the experimental

groups, after medical histories, exams and baseline thermographs were obtained, the

frequencies were applied for 10 minutes to the areas of pathology. Informed consent

was obtained from each subject before their participation in this investigation.

3. Results

Control Group: Thermographic Results

Fig. 1a. Before Fig 1b. After


A.H.J. Fleming et al. / Acoustic/Magnetic Field Assisted Perfusion Study 111


Fig. 4a. Before Fig. 4b. After

Fig. 5a. Before Fig. 5b. After

Experimental Group Thermographic Results: Pulmonary Diseases

Fig. 6a. Emphysema: Before Fig. 6b. Emphysema: After

A.H.J. Fleming et al. / Acoustic/Magnetic Field Assisted Perfusion Study112

Fig. 7a: Pulmonary Fibrosis: Before Fig. 7b. Pulmonary Fibrosis: After

Experimental Group Thermographic Results: Inflammatory Peripheral Vascular Disease

Figs. 8a and 8b. Legs before Figs. 8c and 8d. Legs after

Figs. 9a and 9b. Feet before Figs. 9c and 9d. Feet after

The results of the preliminary investigation were very positive, showing consistently

improved perfusion across thermographs after application. Improvements in perfusion

were shown across the control group as can be seen in the follow-up thermographs

compared to baseline thermographs. Clinically for the cases shown in Figs. 6b and 7b

there was a marked increase in SpO2 and marked improvements in breath sounds,

anxiety levels, and respiratory effort as compared to baseline. The subjects reported

that they were able to inhale more easily as well as exhale without the usual feeling of

restriction. For the cases shown in Figs. 8c, 8d, 9c and 9d. a marked decrease in

inflammation occurred and an increase in perfusion compared to baseline images 8a, 8b,

9a and 9b. Before the application of this acoustic device pedal and post-tibial pulses

were not palpable; after the application of this acoustic device pedal pulses were

palpable, bilaterally.


4. Discussion

How the vibrating of the permanent magnetic fields translates into an induced dynamic

magnetic field was not characterized. Hence it is unclear how the physical motion of

the vibrating applicator converts into a wave form. It is clear however that a form of

pulsed magnetic field is being produced. As discussed by Shupak et al. there are two

fundamentally different biophysical mechanisms that can be associated with exogenous

pulsed magnetic fields: either ionic currents can be induced, or a direct interaction can

occur with some endogenous magnetic field including the magnetic moment of ions,

nuclei, atoms, or molecules. In this instance it appears that the cyclotron motions

associated with outer shell electrons of moving entities within the blood flow are being

increased. This creates a more energetic entity that can ward off the random electric

fields caused by biophysical perturbations such as ischemic attack. This enables blood

to travel further without losing its energy and therefore its motion forwards along the

capillary. Due to the small increments between the magnetic, cyclotron states of atoms

and molecules as opposed to the electric, radial states, the actual frequency of the

magnetic field is not critical as opposed to the acoustic frequency. The biophysical

action of the acoustic field is related to the low frequency modes of vibration of DNA

that control the 'unzipping' or 'melting' reaction that precedes replication and other

stages within the cell cycle. These frequencies are chosen from a physical knowledge

of the DNA, its mass, number of base pairs, width, length between base pairs, angle of

spiral, etc and is critical to replication of the chosen DNA [10, 11, 12].

Acknowledgements

We would like to sincerely thank Rebecca Moss for her thermography work as well as

the entire staff of the Covenant Health Clinic for their assistance, patience, hospitality

and kindness. We further thank Marko Markov for his helpful advice in the

preparation of this report.

References

[1] K. R. Lees et al., NXY-059 for Acute Ischemic Stroke. New England Journal of Medicine; vol. 354, 6,

2006.

[2] J. Hinkle and l. Bowman, Neuroprotection for Ischemic Stroke. Journal of Neuroscience Nursing. Vol

35, 2, 2003.

[3] K. Tolstrup, Non-invasive Resting Magnetocardiographic Imaging for the Rapid Detection of

Ischaemia. European Cardiovascular Disease, May 2006.

[4] N. Shupak, A. W. Thomas, F. S. Prato, Therapeutic Uses of Pulsed Magnetic Field Exposure. URSI

Radio Science Bulletin, no. 307, December 2003.

[5] G. Grant, R. Cadossi, G. Steinberg, Protection against Focal Cerebral Ischemia following Exposure to a

Pulsed Electromagnetic Field, Bioelectromagnetics, 15, 3, 1994, 205-216.

[6] H. N. Mayrovitz, Electromagnetic Linkages in Soft Tissue Wound Healing, in Bioelectromagnetic

Medicine P. J. Rosch and M.S. Markov, Marcel Dekker, 2004.

[7] A. H. J. Fleming, Electromagnetic Self-field Theory and its Application to the Hydrogen Atom. Physics

Essays. September 2005;18:3, http://www.unifiedphysics.com.

[8] A. H. J. Fleming, E. B. Bauer, Self-field Theory a Mathematics for Bioelectromagnetics. BEMS 28,

Cancun, June 11-15, 2005. http://www.unifiedphysics.com.

[9] E. B. Bauer, K.Cooper, A. H. J. Fleming,. The Effects of Acoustic Frequencies on Core Lesions of the

Thoroughbred Racehorse, BEMS 27, Dublin, June 19-25, 2005; http://www.unifiedphysics.com.

A.H.J. Fleming et al. / Acoustic/Magnetic Field Assisted Perfusion Study114

[10] K-C. Chou, Low-frequency vibrations of DNA molecules, Biochem. J. vol. 221, 1984.

[11] E. B. Bauer, private communication, September 2007.

[12] J. A. Fornes, H-Bond vibrations of the a-helix, Phys. Chem. Chem. Phys., no. 3, 2001.


Effect of Pulsed Magnetic Field on Fresh Keeping of Vegetables

Taiki HORI a, Koji FUJIWARA a, Yoshiyuki ISHIHARA a, Toshiyuki TODAKA a, Masao NAKAJIMA b

a Department of Electrical Engineering, Doshisha University, Japan b Shimamoto Noken Co.,Ltd, Japan

Abstract. In this paper, effect and magnetic mechanism of pulsed magnetic field for the green leaf vegetable were examined and evaluated by quantifying the color change, respiration, and stomatal aperture of it. As the results, it is shown pulsed magnetic field exposure suppressed the yellowing and respiration of the green leaf vegetable. Furthermore, it is shown that it keeps the freshness of vegetables, since pulsed magnetic field affects the stoma, from the result that respiration rate and stomatal aperture decreased after pulsed magnetic field exposure.

Keywords. Pulsed magnetic field, Fresh keeping, Vegetable, Stomatal mechanism

Introduction

Recently, performance of the permanent magnet and superconducting magnet technology greatly developed, the effective utilization of magnetic field has been established in various fields such as MRI and ESR in the medical field.

Moreover, recent years, the interest in the safety of food rising, the establishment of the novel fresh keeping technology has been required. Then, the authors have examined the usefulness from the viewpoint of pulsed magnetic field (hereafter PMF) processing technology of the instantaneous exposure type[1][2][3].

This paper shows the effect of PMF on fresh keeping of vegetables was evaluated by quantifying color change of them. Moreover, it was indicated possibility that the fresh keeping effect is obtained by PMF affecting the stoma of vegetables[4]. Therefore, it was investigated magnetic mechanism which worked for fresh keeping effect by evaluating and quantifying the respiration change of vegetables and shape change of stomata.

1. Experimental Conditions and Methods

As a specimen, mibuna leaves which is Japanese green leaf vegetable were used, which cultivated by same farmer, harvest day and producer for reduction in individual specificity. The effect of PMF exposure was examined by quantifying color change, respiration and stomatal aperture of mibuna leaves. In order to maximize magnetic flux

1.1 Experimental Condition



116

to cross to the stoma of leaves, PMF was applied in the normal direction to the leaf surface of the specimen, as shown in Figure 1(a), using the square shape coil (W 390 × L 630 × H 500 mm, 390 turns, L= 8.1 [mH]) and magnetizer (SCH2550-SP, Nihon Denji Sokki Co., Ltd.), as shown in Figure 2.

Figure 1. Exposure direction and measurement portions of color.

Figure 2. Pulsed magnetic field exposure system.

Applied magnetic flux density was 0.05, 0.10, 0.15, 0.20, 0.25[T], exposure frequency was 1 shot, daily observation were done for a week. Specimen was exposed PMF at only first day, and it was not done afterwards. They were preserved in the refrigerator set temperature at 12 °C during measurement period.

The color change of the leaves were evaluated by calculated Yellowing Index (hereafter YI) defined Eq.(1), using 3 kinds of parameter Ln, an, bn (n: progress days after exposure) obtained measurement of leaf color by chroma meter (CR- 300, Konica Minolta Holdings, Inc.), defined in the L*a*b* color system. Moreover, the statistical processing was carried out in order to eliminate individual specificity. Specimens were preserved while it packed by the corrugated cardboard box every other group. The population was made to be 5 packages per group, about 24 leaves per package.

(a) Exposure direction (b) Measurement portions

B

Measurement portions

mibuna leaves

of the flux

1.2 Color Measurement

T. Hori et al. / Effect of Pulsed Magnetic Field on Fresh Keeping of Vegetables 117

The measurement portions were 2 places of the optional 2 leaves in each package, as shown in Figure 1(b).

n

nn a

bLYI ⋅= (1)

The respiration was evaluated by quantity of carbon dioxide in which mibuna leaves was discharged analyzed by the gas chromatography (GC-14BPT, Shimadzu Corp.). Specimens were preserved while it packed by the sealed bowl made of plastic, whose capacity is 4 litters. The population was made to be 2 bowls per group, 3 packages per bowl. The Gas in bowl was gathered by 2 milliliter with a syringe per bowl after 2 hours since sealed up every bowl, and analyzed by gas chromatography, it was repeated 3 times. Then, density of carbon dioxide in bowl Ds was measured. The respiration evaluated by calculated average value of carbon dioxide per hour per kg. The respiration was calculated using Eq.(2), where Dr is density of carbon dioxide in refrigerator, C is capacity of bowl, M is fresh weight of mibuna leaves in bowl, and T is sealed time.

( ) ( )[ ]hmg/kgCO2 ⋅

⋅

−⋅−

=

TMMCDD rs (2)

The physical effect of PMF on the stoma was examined by measuring the stomatal aperture using the microscope (VH-7000, Keyence Corp.). The preservation condition was color measurement similar. The 3 specimens of 1 cm × 1 cm were cut off from the optional leaf in each group every day. The specimen was measured while it was put on the paper which was made to moisten in the water of the temperature equal to the refrigerator in order to prevent that the stoma opens by the external factor such as heat of the outside air and lighting of the microscope during measurement. The stomatal aperture evaluated by calculated averaged stoma area from breadth and length of the stoma measured by the microscope.

2. Results and Discussion

As the daily measurement results of the color change by PMF exposure, the statistics population means estimate of YI in the each exposure condition is shown in Figure (3). However, difference occurs for the value in the first day, and it is unsuitable for evaluating the degree of the degradation, as shown in Figure 3(a). Therefore, in Figure 3(b), the value in the first day is normalized 100 % by YI of the vertical axis which shows the degree of the color change. Therefore, it tends to suppress the yellowing of mibuna leaves in the processing group. Especially, fresh keeping effect of the leaves exposed 0.1T becomes a maximum, and also the statistics 5% significance can be confirmed.

1.3 Respiration Measurement

1.4 Stomatal Aperture Measurement

T. Hori et al. / Effect of Pulsed Magnetic Field on Fresh Keeping of Vegetables118

As the daily measurement results of the daily respiration by PMF exposure, the average value of carbon dioxide in the each exposure condition is shown in Figure 4.

Figure 4(a) shows that the respiration in first and second day is not suppressed, though it is held after the third day. The examination on the breathing rate was carried out from the viewpoint of the respiration peak differed every group. Therefore, in Figure 4(b), the value of respiration peak is normalized 100 % by respiration of the vertical axis which shows the degree of the respiration change. The control shows in the final degradation tendency since the third day and the PMF exposure shows the last degradation tendency since the sixth day. Moreover, it reached the second day at the respiration peak only in 0.1T zone, and it reached the first day at the respiration peak in other.

As the daily measurement results of the daily stomatal aperture by PMF exposure, the average stoma area in the each exposure condition is shown in Figure 5. It is proven that the stoma didn’t open in the process group in first day, while control group greatly

Rat

e of

YI [

%]

1 2 3 4 5 6 7 Time [day]

90

105

100

95

110

120

115

Yel

low

ing

inde

x YI

1 2 3 4 5 6 7 Time [day]

68

80

78

76

74

72

70

82

84

Figure 3. Effect of pulsed magnetic field on color change of mibuna leaves.

Control 0.05T 0.1T 0.15T 0.2T 0.25T

(a) Measurement result (b) Normalized result R

ate

of C

O2 [

%]

1 2 3 4 5 6 7 Time [day]

30

90

80

70

60

50

40

100

110

Figure 4. Effect of pulsed magnetic field on respiration of mibuna leaves.

Control 0.05T 0.1T 0.15T 0.2T 0.25T

(a) Measurement result (b) Normalized result

Val

ue o

f CO

2 [m

g/h

kg]

1 2 3 4 5 6 7 Time [day]

10

35

30

25

20

15

40

45


opened the stoma. It is considered it seems to be because it was prevented by the effect of PMF exposure though the stoma is made to be an open bite, since the stress which environmental change of the harvesting brings about is received.

Therefore, since the PMF effectively affects the stoma, fresh keeping effect seems to have been obtained. It is considered because the eddy current flows by PMF exposure in the stoma and the opening/shutting mechanism of the stoma affects it.

Moreover, it seems to be possible to obtain fresh keeping effect at the specific magnetic flux density because it has retarded the respiration peak at 0.1T zone, and it suppressed the yellowing at 0.1T zone most in the results of experiment of color change.

3. Conclusions

Using mibuna leaves, it was clarified that PMF processing of instantaneous exposure type might be effective for fresh keeping of the vegetable by quantifying color change of specimen after PMF exposure. Moreover, from the viewpoint of the shape change of stoma, as a result of examining the effect of the PMF exposure on the respiration and stomatal aperture it was shown that the breathing rate might be slowed and the stoma area was reduced. Therefore, it was shown that freshness of vegetables was kept, since PMF exposure affects stoma,. Furthermore, it was shown that fresh keeping effect might be obtained by with in PMF at specific magnetic flux density.

Therefore, it is necessary to specify the effective magnetic flux density. In the future, by simulated the stoma with a model, the magnetic flux density will be specified from the force which generates in the stoma by eddy current. In addition, magnetic mechanism which works for fresh keeping will be examined, while the improvement in the reliability for a knowledge acquired this time is attempted by increasing examination cases.

Stom

atal

ape

rture

[pm

2]

1 2 3 4 5 6 7 Time [day]

10

50

40

30

20

60

Figure 5. Effect of pulsed magnetic field on stomatal aperture of mibuna leaves.

Control 0.05T 0.1T 0.15T 0.2T 0.25T

T. Hori et al. / Effect of Pulsed Magnetic Field on Fresh Keeping of Vegetables120

References

[1] K. Yamazoe, Y. Ishihara, T. Todaka, M. Nakajima, Influence of the pulse magnetic field to discoloration of vegetables, The Paper of Technical Meeting on Magnetics, IE.E. Japan MAG-02-76 (2002)

[2] T. Kondo, T. Toshiyuki, Y. Ishihara, M. Nakajima, Effects of pulsed magnetic field on green leaf vegetables, The Paper of Technical Meeting on Magnetics, IE.E. Japan MAG-04-129(2004)

[3] T. Hori, T. Toshiyuki, Y. Ishihara, K. Fujiwara, M. Nakajima, Effect of pulsed magnetic field on fresh keeping of mushrooms, 2007 National Convention Record IE.E. Japan vol.2 No.170(2007)

[4] T. Hori, H. Yamamoto, T. Toshiyuki, Y. Ishihara, M. Nakajima, Fresh keeping effects of pulsed magnetic field on fruits and vegetables, IEICE Society Conference B-4-44 (2006)


Mutagenicity and Co-mutagenicity of

Strong Static Magnetic Field in Yeast Cells

Masateru Ikehataa,1

, Sachiko Yoshiea

, Sachi Matsumotoa

,

Yuji, Suzukib

, Toshio Hayakawaa

a

Railway Technical Research Institute, Kokubunji, Tokyo 185-8540, Japan,

b

The Jikei University School of Medicine

Abstract. Mutagenicity and co-mutagenicity of strong static magnetic field up to 5

T was estimated in budding yeast Saccharomyces cerevisiae XD83. We observed

that exposure to a 5 T static magnetic field resulted in a slight but significant

increase in gene recombination frequency while reverse mutation was not altered.

This mutagenic effect showed a dose response relationship as J-shape. In co-

mutagenicity assay, it was found that exposure to a 5 T static magnetic field has

tendency to enhance the mutagenic potential of Zeocin (Phleomycin) that is an

antibiotic agent by free radical production. These results suggest that strong static

magnetic field would have small but detectable mutagenic and possible weak co-

mutagenic potential. However, the extent is estimated extremely small by

comparison with other mutagens such as ultraviolet irradiation.

Keywords. static strong magnetic field, mutagenicity, co-mutagenicity, yeast

Introduction

The chance for exposure to various magnetic and electromagnetic fields in general

public and working environment are increasing. However, we do not have enough data

to guarantee the safety of magnetic field exposure. To evaluate the biological effects

by exposure to magnetic fields, large number of research were conducted in various

frequencies where a social anxiety is caused in recent years. However, there are not

enough studies to evaluate the biological effects of static magnetic field while

opportunities for exposure to high density magnetic field such as MRI are increasing.

It was reported that exposure to strong static magnetic field caused small increase

of somatic recombination in wing spot test of Drosophila melanogaster [1], increase

mutation frequency in forward mutation assay in SOD deficient Escherichia coli [2]

and enhancement of mutagenicity of DNA reactive mutagen in reverse mutation assay

in E. coli [3]. However, the mechanism of the mutagenic effect has not been

determined yet. On the other hand, no mutagenic effect was observed in bacterial

mutation assay (Ames’ test) using Salmonella typhimurium and E. coli [3]. Therefore,

additional research evidences will be necessary to understand the mutagenic effects of

magnetic fields.

In this study, mutagenicity and co-mutagenicity of a strong static magnetic field

was examined using budding yeast Saccharomyces cerevisiae as a eukaryote model.

1

Corresponding Author: Masateru Ikehata, Senior researcher, Biotechnology Laboratory,

Environmental Engineering Division, Railway Technical Research Institute, 2-8-38, Hikari, Kokukbunji,

Tokyo 185-8540, Japan; E-mail: [email protected]



122


Saccharomyces cerevisiae XD83 (MATa/MATα, lys1-1/lys1-1, arg4-4/arg4-17, RAD)

was obtained from American Type Culture Collection and was used as the tester strain

in this study. For magnetic field exposure, we used a superconducting magnet (JS-500,

Toshiba Co., Japan). This magnet is able to generate up to a 5 T homogeneous static

magnetic field with five percent distribution within 10 cm from the center of the bore

(diameter; 20 cm). S. cerevisiae XD83 was pre-cultured to late log phase

(approximately 108

cells/ml) in YPD medium.

In mutagenicity assay, 0.1 ml of cell suspension was mixed with molten soft agar

(0.6 % Bacto-agar, 0.5 % NaCl) and poured on to low lysine synthetic complete plate

for detecting point mutation frequency on lys 1-1. 0.1 ml of 1/100 diluted cell

suspension was mixed with molten soft agar and poured on to low arginine synthetic

complete plate for detecting gene conversion frequency on ARG4 allele (between arg

4-4 and arg 4-17).

In co-mutagenicity assay, Zeocin (Phleomycin) was used as a chemical mutagen.

Cell suspension including cells and molten soft agar with 0.25, 0.13, 0.06 and 0.03 µg

of Zeocin was poured on to selection plates for point mutation (LYS1) and gene

conversion (ARG4), respectively.

At least 6 plates were made for each test condition and randomly divided into two

groups. One group was exposed to a static magnetic field for 4 days at 30 ± 0.5 o

C as

exposed group. The other group was incubated in a conventional incubator as

unexposed control. Number of colonies on each plate was scored as revertant and the

mutation frequency was calculated.

2. Results and discussion

Exposure to a 5 T static magnetic field resulted in a slight but significant increase in

gene conversion frequency in ARG4 locus while reverse mutation in lys1-1 was not

altered in mutagenicity assay (Table 1). This mutagenic effect disappeared on

exposure to a 2 T static magnetic field and was even lower than the control on exposure

to a 1 T static magnetic field. When cells were exposed to a 0.5 T static magnetic field,

there was no difference in the frequency of reverse mutation in both ARG4 and lys1.

These results suggest that exposure to a strong static magnetic field shows weak

mutagenicity and its threshold would be above 2 T in this tester strain. In addition, the

dose response relationship between magnetic field density and mutagenic effect

showed J-shape. In our previous study, extent of mutagenic effect of strong static

magnetic field was increased linearly up to 2 T and saturated in wing spot test of

Drosophila melanogaster [4] and co-mutagenicity of Ames test [3]. In case of these

assays, tester strains have partial deficiency of DNA repair ability and therefore these

strains are sensitive to various mutagens. On the other hand, S. cerevisiae strain used

in this study is proficient for DNA repair and its J-shape dose response relationship

between magnetic field density and mutagenic effect was different from DNA repair

deficient Drosophila and E. coli. These different responses would be reasonable if the

exposure to strong static magnetic field caused an increase of DNA lesion frequency.

Obviously, although a strong magnetic field even at 5T does not have enough energy to

modify the covalent bond of DNA directly, indirect effects such as increase of

oxidative damage by exposure to a strong static magnetic field reported by Watanabe et

M. Ikehata et al. / Mutagenicity and Co-Mutagenicity of Strong Static Magnetic Field 123

al. [5] would be the cause of increase in the mutation frequency.

In co-mutagenicity assay, slight increase in gene conversion frequency of exposed

group in ARG4 locus was observed in all of four concentrations of Zeocin treatment

groups (0.03, 0.06, 0.13 and 0.25 µg/plate), respectively. Figure 1 shows the gene

conversion frequency in ARG4 locus induced by 0.03 µg/plate of Zeocin, Zeocin with

exposure to a 5 T static magnetic field and UV irradiation. In this figure, gene

conversion frequency in exposed group was slightly higher than control (unexposed)

group. Figure 2 shows the gene conversion frequency in ARG4 locus induced by 0.06

µg/plate of Zeocin, Zeocin with exposure to a 5T static magnetic field and UV

irradiation. Gene conversion frequency in exposed group was also slightly higher than

control (unexposed) group. Figure 3 shows the gene conversion frequency in ARG4

locus induced by 0.13 µg/plate of Zeocin, Zeocin with exposure to a 5 T static

magnetic field and UV irradiation. Gene conversion frequency in exposed group was

also slightly higher than control (unexposed) group. Although we observed tendency to

increase mutagenicity of Zeocin by exposure to a 5 T static magnetic field, all of these

increases were not significant by Student’s t-test, respectively.

Table 1 Mutagenicity of static strong magnetic field in S. cerevisiae XD83

Treatment lys+ mutants/10

7

survivor ARG+ mutants/10

4

survivor

(point mutation) (gene conversion/recombination)

Control 9.7 ± 2.5

a

2.4 ± 0.7

0.5 T N.D.

b

2.1 ± 0.3

1 T 10.1 ± 3.0 1.9 ± 0.7

2 T N.D. 2.2 ± 0.1

5 T 9.8 ± 3.5 3.3 ± 0.8 *

UVC 18 J/m

2

146.1 ± 20.8 * 18.4 ± 3.9 *

*Significantly higher than the control group at 1 % level by Student's t -test.

a) Standard division from at least three independent experiments

b) Not Determined

0

200

400

600

800

1000

Control Exposure

(5 T)

UVC

Treatment

Arg

+ co

lo

ny

/p

late

Fig.1 Synergistic effect (co-mutagenic effect) of 5 T

magnetic field on mutagenicity of phleomycin (0.03

µg /plate) in S.cerevisiae XD83.

0

200

400

600

800

1000

Control Exposure

(5 T)

UVC

Treatment

Arg

+ co

lo

ny

/p

late

Fig.2 Synergistic effect (co-mutagenic effect) of 5 T

magnetic field on mutagenicity of phleomycin (0.06

µg /plate) in S. cerevisiae XD83.

(18J/m2

) (18J/m2

)

M. Ikehata et al. / Mutagenicity and Co-Mutagenicity of Strong Static Magnetic Field124

Zeocin is a member of bleomycin family and its mode of action is to break the

DNA strand by producing free radicals after intercalation into DNA strand. Thus, these

results suggest that mutagenicity of Zeocin that depends on free radicals was possibly

affected by exposure to a 5T static magnetic field. Although we could not observe

tangible effects, the data showed tendency of enhancement of mutagenicity by Zeocin

treatment. Thus, it is inferred that effect on free radical behavior by exposure to strong

static magnetic field would be an factor of increase of gene conversion frequency in

this tester strain. In addition, this result is consistent with the result in mutagenicity

assay and our previous results. Therefore, results in this study support our hypothesis

about the mechanism of mutagenicity by exposure to magnetic field.

Table 1 also shows that weak UV irradiation which estimated to be approximately

1/5 to 1/10 that of average sunlight in Japan, caused significant increase of both ARG4

and lys1 reverse mutations in the tester strain used in this study. In a comparison of the

results of exposure to strong static magnetic field and the UV irradiation in this study,

the extent of mutagenicity of strong static magnetic field was estimated to be extremely

small since weak UV exposure (18 J/m2

) is approximately 20 times more effective than

strong static magnetic field which are at least 10,000 times stronger than those in the

environment and long exposure duration (48 hours). This suggests that effect of static

magnetic field even in a 5 T (100,000 times higher than geo-magnetic field) is

sufficiently small. Therefore, in view of risk estimation, exposure to static magnetic

field would be negligible as a component of risk in public environments.

References

[1] Y. Takashima, J. Miyakoshi, M. Ikehata, M. Iwasaka, S. Ueno and T. Koana, J. Radiat. Res., vol. 45, pp.

393-7, 2004

[2] Q.M. Zhang, M. Tokiwa, T. Doi, T. Nakahara, P.W. Chang, N. Nakamura, M. Hori, J. Miyakoshi and S.

Yonei., Int J Radiat Biol., vol. 79, pp. 281-6, 2003

[3] M. Ikehata, Y. Suzuki, H. Shimizu, T. Koana and M. Nakagawa, Mut. Res., vol. 427, pp. 147-156, 1999

[4] T. Koana, M. O. Okada, M. Ikehata, and M. Nakagawa: Mut. Res., vol. 373, pp. 55-60, 1997

[5] Y. Watanabe, M. Nakagawa and Y. Miyakoshi, Industrial Health, vol. 35, pp. 285-290, 1997

0

200

400

600

800

1000

Control Exposure

(5 T)

UVC

Treatment

Arg

+ co

lo

ny

/p

late

Fig.3 Synergistic effect (co-mutagenic effect) of 5

T magnetic field on mutagenicity of phleomycin

(0.13 µg /plate) in S. cerevisiae XD83.

(18J/m2

)

M. Ikehata et al. / Mutagenicity and Co-Mutagenicity of Strong Static Magnetic Field 125

Model for Investigation of Microwave Energy Absorbed

by Young and Mature Living Animals Roman KUBACKI a, Jaromir SOBIECH a, Edward SĘDEK b

a Military Institute of Hygiene &Epidemiology, Poland b Telecommunication Research Institute, Poland

Abstract. In the paper ellipsoidal phantom model for investigation of energy absorbed by living organisms has been proposed. Calculations using the FDTD method of specific absorption rate (SAR [W/kg]) have been presented in the function of frequency, in the frequency band of 0,8 – 1,8 GHz, for plane wave and waveguide exposure conditions. Phantom model has been filled with liquid of electrical properties equivalent to electrical properties averaged over whole animal body. Values of the averaged electrical properties were established by measuring of the ε’ and ε” of minced animal body. The validation of this phantom method has been done by measuring of SAR of living (anesthetized) mice in rectangular waveguides. The investigation of SAR of mice at different ages (10 day-old, 30 day-old and 4 month-old) demonstrates that young mice absorb the same energy or even lower as old (mature) animals.

Keywords. Electromagnetic energy absorbed by organisms, electrical properties of tissues, phantoms

Introduction

The increasing popularity of mobile phones in our live has aroused interest about potential health risk due to exposure to microwave (MW) energy. The investigation of potential adverse health effects has been magnified by the fact that most part of energy emitted by handset is absorbed by head. Thus, the presented papers in the literature are focused on assess of the MW energy level as well as its distribution inside the head. Recently one particular issue is intensively debated, i.e., whether the exposure level of MW energy from mobile phone is higher for children than for adults. Some researchers [2, 3] have reported significant increase in MW energy absorption from exposure to mobile handset radiation in the heads of children compared to heads of adults. In 1996 has been announced [2] that in some parts of the children head the peak of specific absorption rate was 50 % higher compared to adults under the same exposure conditions. Because of potential higher risk of children exposed to MW radiation in the Steward Report [9] describing known interactions of electromagnetic radiation with living systems has been recommended that children less than 16 years of age should be discouraged from using mobile telephones since they may absorb more electromagnetic energy. According to the Steward Report this effect is due to smaller heads, thinner skulls and higher tissue conductivity. However, there exist papers [7] demonstrating that the value of absorbed energy is similar in the heads of adults and children. The



126

attempt to review the existing state of research regarding the exposure of children heads has been done by Christ et al. [1]. Summing up published data the following disadvantages in assessing of energy absorbed by children should be underlined:

- The simple models of children heads and their phantoms are designed for calculations based on tissues with electric parameters equivalent to muscle tissue of adults. Last years studies have shown increased values of tissue permeabilities (ε) and conductivities (σ) of newborn and young animals comparing to mature organisms [5, 6, 8]. The information about higher values of ε and σ has been used credulously for formulating arguments that children may absorb higher level of microwave energy.

- In computational calculations based on FDTD methods the models of heads have been taken from Visible Human Project provided high-resolution slices of a male cadaver but there is a problem with anatomically correct model of children head. Thus, numerical model of child head is received as a proportionally scaled down model of adult head, even it is underlined that exist significant disagreements of proportions of adult and child heads. The applicability of scaled down adult head for realistic absorption assessment of child head is questionable.

1. Assessing of the SAR

The level of the energy absorbed in the body can be precisely described by the specific absorption rate (SAR [W/kg]). This parameter gives information about peak and mean energy absorbed inside the body. However, for living objects the assessing of SAR is not an easy task in calculations and especially by measuring. Numerical techniques, especially the finite-difference time-domain methods (FDTD), are the most useful techniques to calculate the SAR values. These methods offer different possibilities of calculations beginning from simple shapes of phantoms up to realistic models of adult organisms with particular body parts established by MRI techniques. Using the FDTD methods it is possible to predict whole body as well as localized value of SAR under a wide range of exposure conditions. The important disadvantage with FDTD methods introduced to lossy objects with complex shapes (animals and human) is that these methods should be verified with the measuring data. Attempts to validate the computer models must use phantoms and laboratory animals.

There exist some methods of measuring of the SAR. However, it is not possible to measure values of SAR of human body in a direct way. This is because the most popular techniques base on the temperature or electric field strength (power absorbed) measured inside the body. The calorimetric or waveguide measuring techniques of energy absorbed can be used only for phantoms or small animals. Taking into account the above disadvantages with calculating and measuring of SAR of living organisms especially at different ages the main aim of the study was to develop the phantom method which can be verified by measured values of SAR of small living animals. The ellipsoidal phantom model has been designed to calculate the energy absorbed at different incident field conditions. It can be used for plane wave, typical for emission from base station antennas or for near-field from handset, as well as for different electrical parameters and geometrical sizes. The main advantage of the proposed method is that phantom is filled with liquid having real and imaginary permittivity (or conductivity) equivalent to averaged values over all animal body. Phantom models described in the literature were filled with stuff having electrical

R. Kubacki et al. / Model for Investigation of MW Energy Absorbed by Living Animals 127

parameters of muscle in spite of the fact that in the microwave band of frequency the significant part of energy is absorbed not by muscle but rather skin and by subdermic tissues. In the proposed attempt phantom with average value of ε’, ε” (or σ) is “seen” by incident microwave ray as an animal body and level of energy absorbed is adequate to total energy absorbed by whole animal. Mice were chosen for this investigation. The averaged values of ε’, ε” of whole mouse body were measured using the open-ended coaxial probe technique [5]. Calculations were realized with FDTD method. The validation of this phantom method has been done by measuring of SAR of living (anesthetized) mice in rectangular waveguides.

Animals were of different ages, e.g. of 10 day-old, 30 day-old and 4 month-old (mature).

The measurements have been realized “in vivo” conditions – mice were anesthetized for period of measurements. The value of rms of electric field strength incident to mouse was of 61,4 V/m (power density of 10 W/m2).

2. Measurements of Energy Absorbed by Animals

The values of SAR were measured in rectangular waveguides in which animals were positioned at the maximum field of the TE10 mode. To improve the accuracy of measurements of the energy absorbed by the objects (PA) in rectangular waveguide a modification of the method by Guy et al. [4] has been designed. Proposed method has been developed for rectangular waveguide terminated with waveguide-coaxial junctions. In this method there is a need to measure fractions of power - transmitted and reflected - in the empty waveguide, as well as with waveguide with animal. Another requirement of this method is that all measurements must be realized with the same power incident (PIN). For the empty waveguide the sum of power can be expressed as follows:

000 WRTIN PPPP ++= (1) while for waveguide with animal:

AWRTIN PPPPP +++= 0 (2) where: PIN - power incident to the waveguide-coaxial junction, PT0 - power transmitted to the terminal (next waveguide-coaxial junction), PR0 - power reflected, PW0 - power absorbed by the walls of waveguide, PT, PR - power transmitted and reflected with the animal in waveguide, PA - power absorbed by the animal. Taking into consideration the same value of power incident (PIN), the power absorbed by specimen (PA) can be calculated according an equation:

( ) ( )RRTTA PPPPP −+−= 00 (3)

R. Kubacki et al. / Model for Investigation of MW Energy Absorbed by Living Animals128

The formula (3) allows calculating of the power absorbed by the animal as a function of power differences between empty waveguide and waveguide with animal measured at the same waveguide ports. The final formula of SAR is as follows:

⎥⎦

⎤⎢⎣

⎡=

kgW

mPSAR A (4)

where: m is the weight of animal.

Two rectangular waveguides WR-975 and WR-650 were used for these measurements of power absorbed by animals in the band of 800 MHz up to 1800 MHz. The internal dimensions of waveguides in the waveguide cross-section were big enough comparing to longer axis of measured animal. Thus the only small animal can be measured using the waveguide methods. From this reason mice were used in this investigation. For frequencies upper than 1800 MHz rectangular waveguides are too narrow for such measurements even with small mice.

3. Validation of SAR Calculation Method

Taking into account lack of anatomical model of mouse with particular body parts in this attempt ellipsoidal phantoms having suitable geometrical and electrical parameters equivalent to exposed mouse have been considered for calculations. In case of phantoms of mice the dimensions of ellipsoids (a×b×c) have been established to suit the geometry of animal. However, the most important task in this attempt is the information about permittivity (ε) and conductivity (σ) of phantom stuff. In the literature homogeneous phantoms having electrical parameters equivalent to electrical parameters of adult muscle are presented. Values of ε and σ of animals are rarely presented in the literature (mainly for one frequency) and refer to mature animals. For this study values of permittivity (ε) and conductivity (σ) of adult and young mice have been established by measuring. We decided to consider in evaluation not only the selected tissue (e.g. muscle) but rather the average values of ε and σ over all tissues. In this case the whole animal has been minced and values of ε and σ of such a homogeneous stuff have been measured. This model could be more suitable for assessing of the energy absorbed by whole animal because it includes not only muscle but also external tissues such skin, subdermic fat, bones. In fact, in microwave band of frequency external tissues such skin and subdermic fat play significant role in attenuating of electromagnetic energy. The method of measuring technique of ε’ and ε” using the open-ended coaxial probe (Hewlett Packard network analyzer) and method of preparing of homogeneous staff have been presented in [5]. These techniques have been adapted to measure the average value of ε’ and ε” of mice at different ages.

The SAR values of ellipsoidal phantoms having average electrical parameters over all tissues of mice at different ages have been calculated using the FDTD method (the package CONCERTO, Vector Fields Ltd. [10]). The weights and dimensions of the ellipsoidal phantoms have been chosen to be comparable to mice weights. Calculations were realized for the same waveguide conditions of incident field as during measurements. Values of SAR have been calculated based on the electric field strength distribution inside the body (Ei), according the following formula:


ρ

σ2iE

SAR = (5)

where: Ei – rms value of the electric field strength inside the body, σ - conductivity of body, ρ - density of body. The obtained results have been presented in Figure 1.

Figure 1. Measured values of SAR for anesthetized mice (SAR meas (W/kg)) and calculated values of SAR for ellipsoidal phantoms of averaged electrical properties (SAR cal (W/kg)) in waveguide conditions: Graph A – mice of 10 day-old, Graph B – mice of 30 day-old, Graph C – mice of 4 month-old [11]

In Fig. 1 calculated and measured values of SAR of young mice (of 10 day-old and 30 day-old) and mature mice (of 4 month-old) in rectangular waveguides have been presented in function of frequency [11]. Good agreement between measured and calculated data was obtained. The differences between calculated and measured graphs are much significant for higher frequency because geometrical sizes of animals are not

SAR cal (W/kg)

SAR meas (W/kg)

0,8 1,0 1,2 1,4 1,6 1,8

C

0,0

0,2

0,4

0,6

0,8

f [GHz]

0,8 1,0 1,2 1,4 1,6 1,8

B

0,0

0,2

0,4

0,6

0,8

f [GHz]

A

0,0

0,2

0,4

0,6

0,8

0,8 1,0 1,2 1,4 1,6 1,8

f [GHz]


small enough comparing to the cross-section of waveguide. In this case higher part of microwave energy could be dissipated in waveguide walls.

4. Results of SAR Calculations in the Plane-Wave Condition

This method of investigation has been introduced to assess of the SAR values for ellipsoidal phantoms exposed to plane-wave with vector of electric field parallel to the longer axis of ellipsoid. Obtained results of SAR have been presented in Figure 2 for phantoms of electrical properties equivalent to averaged electrical properties of 10 day-old, 30 day-old and 4 month-old mice.

Figure 2. SAR calculated for ellipsoidal phantoms of averaged electrical properties for plane-wave incident field: Graph A – mice of 10 day-old, Graph B – mice of 30 day-old, Graph C – mice of 4 month-old

5. Conclusions

1. The good agreement between measured SAR values of whole body animals and calculated values for ellipsoidal phantoms in waveguides proves that it is possible to use this model for assessing of the energy absorbed at different electromagnetic field conditions, eg. plane-wave and for different electrical parameters and geometrical sizes.

2. Values of SAR increase in function of frequency in the band of 0,8 – 1,8 GHz at the same electric filed strength incident. This tendency is significant in spite of decreasing values of ε’ and ε” vs. frequency. Lower values of ε’ and ε” lead to

f [GHz]

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0,8 1,0 1,2 1,4 1,6 1,8

A

f [GHz]

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0,8 1,0 1,2 1,4 1,6 1,8

B

f [GHz]

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0,8 1,0 1,2 1,4 1,6 1,8

C


lower level of energy reflected at the boundary “air-object” and higher level of microwave energy enters into the bod

3. Comparing waveguide (Figure 1) and plane-wave (Figure 2) exposure conditions it turned down that animals can absorb higher level of microwave energy in case of plane wave incident field. This is because in waveguide with the TE10 mode the electric field has cosine pattern and only central part of the animal is exposed to maximum of the field, while the remaining part of the body is exposed to lower value of electric field. At higher frequency when narrower waveguide must be used the significant part of the animal body is exposed to lower value of electric field. This causes lower value of SAR in the body in waveguide exposure conditions especially at higher frequency.

4. The main goal of this investigation was to study if young organisms absorb more microwave energy as it was suggested in the literature. The obtained data of SAR for mice at different ages does not confirm this suggestion and demonstrates that young mice absorb the same or even rather lower energy level as old (mature) animals.

References

[1] A. Christ, N. Kuster, Differences in RF energy absorption in the heads of adults and children, Bioelectromagnetics, Suppl. 7 (2005), S31-44.

[2] O. P. Gandhi, G. Lazzi, C. M. Furse, Electromagnetic absorption in the human head and neck for mobile telephones at 835 and 1900 MHz, IEEE Trans. Microwave Theory Tech., vol. 44, no. 10 (1996), 1884-1897.

[3] O. P. Gandhi, Gang Kang, Some present problems and a proposed experimental phantom for SAR compliance testing of cellular telephones at 835 and 1900 MHz, Phys. Med. Biol., vol. 47, no. 9 (2002),, 1501-1518.

[4] A. W. Guy, J. Wallace, J. A. McDougall, Circularly polarized 2,450 MHz waveguide system for chronic exposure of small animals to microwaves, Radio Sci., vol. 14, no. 6S (1979), 63-74.

[5] R. Kubacki, J. Sobiech, K. Wardak, The investigation of dielectric properties of young rabbit tissues in microwave frequencies, Proc. of Conference on Computational and Applied Electromagnetics, Maribor, 2005, 36-38.

[6] A. Peyman, A.A. Rezazadeh, C. Gabriel, Changes in the dielectric properties of rat tissue as a function of age at microwave frequencies, Phys. Med. Biol., vol. 46, no. 6 (2001), 1617-1629.

[7] E. Schonborn, M. Burkhardt, N. Kuster, Differences in energy absorption between heads of adults and children in the near field of sources, Health Phys. vol. 74, no. 2 (1998), 160-168.

[8] M. Thurai, V. D. Goodridge, R. J. Sheppard, E. H. Grant, Variation with age of the dielectric properties of mouse brain cerebrum, Phys. Med. Biol., vol. 29, no. 9 ((1984), 1133-1136.

[9] Independent Expert Group on Mobile Phones, Mobile Phones and Health, The Steward Report, National Radiological Protection Board, Chilton 2000, Available: http://www.iegmp.org.uk.

[10] Concerto User Guide, Vector Fields Limited, Warsaw 2004. [11] R. Kubacki, J. Sobiech, The investigation of Specific Absorption Rate of microwaves in range of

mobile and radar devices by young and mature mice, Proc. Int. Microwave Radars and Wireless Communications Conf., Krakow, (2006), 451-454.


A Dosimetric Study for Experimental

Exposures of Vegetal Tissues

to Radiofrequency Fields

Simona MICLĂUŞ a1

, Mihaela RĂCUCIU b

a

Land Forces Academy, Sibiu, Romania

b

University “Lucian Blaga”, Sibiu, Romania

Abstract. The paper aims to calculate the specific absorption rate (SAR) in a

sample composed by a group of plant seeds exposed either to a very low-level

900MHz radiation or to a high level 2.45MHz radiation. The exposure systems

were a TEM cell and a microwave oven respectively, and the incident

electromagnetic wave was a continuous one. Since interesting biological effects

were observed in both exposure cases after plantlets were developed from

irradiated seeds, a proper dosimetric assessment was needed. In present work four

dosimetric approaches were applied and the results, limitations and uncertainties

are discussed.

Keywords. RF exposure, plant seeds, specific absorption rate, experimental RF

dosimetry.

Introduction

Biological effects of radiofrequency (RF) field exposure at the level of vegetal tissue as

a living object were not much investigated. However, environmental studies

concerning electromagnetic field impact should take this into account. Besides humans

and animals, the plants might be sensitive to low-level exposure as well, mostly on

long-term.

In the case of laboratory study on plants, one of the important aspects in biological

effect analysis is related to a pertinent characterization of the exposure conditions and a

high quality dosimetric assessment. In this respect, present paper aims to determine the

RF absorbed power or specific absorption rate (SAR) into Zea mays seeds, exposed in

two experimental cases: a) non-thermal exposure into a TEM cell at 900MHz; b) short-

duration, high thermal exposure at 2.45 GHz. Three dosimetric approaches are applied

and the limitations and uncertainties are discussed.

The main experimental work focused on identification of the biological effects due

to 900MHz RF exposure of Zea mays seeds, in early development stages of plantlets.

For present work however, only the exposimetric and dosimetric analysis of these

exposure experiments are made.

1

Corresponding author: “Nicolae Balcescu” Land Forces Academy, 3-5 Revolutiei St., 550170, Sibiu,

Romania; E-mail: [email protected]


133


The first exposure and dosimetric system is composed by a TEM cell, a RF signal

generator, two spectrum analyzers, a power sensor connected to one analyzer, and a

second directional power sensor connected to the second analyzer. These power sensors

allow measurement of the forward, reflected and transmitted powers into the sample

inserted in the TEM cell (Figure 1). The sensors are used for determining the absorbed

power into the sample, by the differential power technique [1], as a first dosimetric

method. After absorbed power Pabs

determination, SAR calculation is possible, by

dividing Pabs

to the sample mass. During irradiation, a non-perturbative, non-

interferential thermal fluoroptic probe (model Luxtron One) was present in the sample

body, in order to continuously monitor any temperature variation in the sample. The

probe was connected to the computer with afferent data acquisition and processing

software. The used irradiation signal was a continuous wave (CW) on f = 900MHz,

with an input power Pin

= 20mW that enters the TEM cell. The sample consisted on a

number of 55 Zea mays seeds, each one dimensions of 7mm x 4mm x 4mm, uniformly

spread in a polystyrene Petri dish with a diameter of 90mm, placed in the uniform field

area of the TEM cell (half distance between septum and exterior conductor). The

uniformity of the field in the irradiation area of the unloaded TEM cell was prior

analyzed by using a computational method [2]. It is of big importance that the external

field Eext

in the irradiation area to be as uniform as possible.

A second method for SAR assessment in the sample exposed inside the TEM cell at

900MHz CW was a theoretical one and more approximate, but still interesting for

comparison and this was the semi-empirical relation for SAR calculation in the case of

free space irradiation of a spheroidal biological model [1].

Figure1. Exposure and dosimetric set-up for the 900MHz low-level irradiation of Zea mays seeds

in the TEM cell

S. Miclaus and M. Racuciu / A Dosimetric Study for Experimental Exposures of Vegetal Tissues134

The third theoretical dosimetric method is based on SAR calculation given by the

formula:

ρ

⋅σ

=

2

E

SAR (1)

where E is the rms value of the internal E-field in the seed, σ is its electrical

conductivity and ρ is the mass density.

The second exposure and dosimetric system is composed by a microwave oven

(MO) with an incident power Pin

’=800W at f’=2.45GHz and the fluoroptic non-

perturbative temperature probe, connected to a computer enabled by the data

acquisition software. This system gives a very high exposure and a high temperature

increase of the sample, so only very short exposures were applied. The SAR was

computed for one seed at once, by the method of temperature slope of the heating curve

(the fourth dosimetric method), measured by the temperature probe which was inserted

in a hole inside the seed, in good contact with the seed surface.

A number of measurements were made for different seeds in the sample, and the

average SAR calculated.With this method, the heating capacity of the seed, cs is needed

for SAR estimation, but one has to take into account its variation with temperature,

which is at all negligible in this case.


2.1. TEM Cell Exposure

The incident power density Sin

on the sample was theoretically calculated. Knowing the

theoretical impedance of the cell, Z0

= 50Ω, the electric potential U between the TEM

cell conductors may be calculated and then the theoretical incident E-field intensity.

The distance between the septum and the outer conductor of the TEM cell being D =

0.23 m, finally the Sin

is calculated:

1VZPUin

=⋅= (2)

m

V34.4

D

U

E == (3)

2

0

2

m

mW50

Z

E

S

in

== (4)

During whole irradiation procedure in the TEM cell, no temperature elevation could be

measured by the Luxtron one probe, and since it is a sufficient sensitive probe model,

we could conclude that the irradiation was non-thermal. Further, the average SAR in

the Zea mays seeds sample had to be determined.

S. Miclaus and M. Racuciu / A Dosimetric Study for Experimental Exposures of Vegetal Tissues 135

By using the differential power method [1], we first determined the absorbed

power in the unloaded TEM cell (no sample inside):

routinabsPPPP

1

−−= (5)

where: Pabs1

is the absorbed power in the unloaded TEM cell, Pin

is the forward power,

Pout

is the output power and Pr is the reflected power (back). The three powers are

measured by the power sensors connected to spectrum analyzers. In a similar way, the

absorbed power is determined when the sample is inserted in the TEM cell (Petri dish +

seeds inside), and this is called Pabs2

. The Pabs3

is then determined and it represents the

absorbed power when only the Petri dish is present in the cell (empty Petri dish).

Finally, the absorbed power in the ensemble (sample) of 55 seeds is determined as:

312 absabsabsabs

PPPP −−= (6)

In the experimental case, when a series of 8 determinations were applied on 8

different samples, the absorbed power wasdetermined to be:

mW004.0008.0Pabs

±= (7)

While the sample mass of the 55 seeds was m = 8.35±0.42 g, the average SAR

value experimentally determined was:

kg

mW5.095.0

m

P

SARabs

±== (8)

Due to the fact that the measured powers are very low and near to the precision

level of the measurement systems, one should carefully take this aspect into account.

From this point of view it is advisable that the Pin

to be increased for a more reliable

result. Comparing the obtained value of SAR with the ICNIRP guidelines values to the

population safety for whole body average SAR which is 80mW/kg, the value we

obtained here is much lower, and is of the order of magnitude of general environmental

induced SAR levels in the 900 MHz band. Nevertheless, this SAR level induced some

interesting biological effects in plants developed from the irradiated seeds [3].

Theoretical calculation:

By using the semi-empirical formula for a spheroidal model of one seed, we could

assess in a second way the average SAR in the sample. For an incident power density

of 1 mW/cm² and an E-polarization, when a plane wave impinges the model having the

long semi-axis a and the short semi-axis b (in meters), the SAR in the spheroid (seed)

can be calculated by the formula given in paragraph 5.1.1. of [1]:


( ) ( )

2

2

0

2

22

0

2

3

022

0

2

5401

0

32

0

2

1

1

f

f

A

f

f

10

ffu

f

f

AAffu

f

f

A1

f

f

A

kg

WSAR

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⎟

⎠

⎞⎜

⎝

⎛

−+

−+−+

= (9)

with ( )01

ffu − si ( )02

ffu − functions of the form:

( )

⎩

⎨

⎧

>

<

=−

01

01

01

ffif1

ffif0

ffu (10)

f0 represents the resonance frequency of the model, and is given by:

( ) ( )[ ]2

1

22228

0

baa81075.2Hzf

−

+π+×= (11)

For the calculation of 01

f and 02

f , we used:

32

2

0

01

b

a

020.0

b

a

295.0a090.1

b

a

239.1a421.0

f

f

⎟

⎠

⎞

⎜

⎝

⎛

⎟

⎠

⎞

⎜

⎝

⎛+−++−= (12)

3

2

2

0

02

a120.34

b

a

068.0a810.50

b

a

502.0a800.21

f

f

+−−+= ⎟

⎠

⎞

⎜

⎝

⎛ (13)

And constants 51

AA … are given by:

2

1

1

b

a

660.5a739.0

b

a

172.0a690.10994.0A +++−−=

−

(14)

2

1

2

b

a

141.2a190.1

b

a

170.399a400.41914.0A −−++−=

−

(15)

3

2

2

3

a369.5

b

a

0016.0a733.8

b

a

084.0a822.4A ++−−= ⎟

⎠

⎞

⎜

⎝

⎛ (16)


3

2

2

4

a640.0

b

a

0075.0a804.0

b

a

075.0a335.0A +−−+= ⎟

⎠

⎞

⎜

⎝

⎛ (17)

4

1

20

5

A

−

ε

ε

= (18)

where 20

ε is the complex permittivity at 20GHz.

For the Zea mays seed spheroidal model, we considered: a = 3.5mm and b = 2mm.

The calculated resonance frequency is: f0= 17.2 GHz. Then,

45.1

f

f

0

01

= and 747.0

f

f

0

02

= (19)

91.5162A1

= and 65.1515A2

= (20)

These give the average SAR per 1mW/cm2

:

kg

W104.9SAR

3

norm

−

×= (21)

In our case in the TEM cell 2

m

mW50S

in= , so the average SAR in one seed is:

kg

mW047.0SAR = (22)

This value is however affected by significant uncertainties. First, the semi-

empirical formula is known to give an uncertainty of up to 15% and it was only

validated on animal tissues. Furthermore, the Sin

is calculated here in ideal conditions,

then the hypothesis that the E-field in the TEM cell is E-polarized regarding the seed

position is not true, then only part of the incident power density impinge the seed itself,

part of it being dissipated in the dielectric material of the Petri dish. To conclude, the

uncertainty for this type of calculation is difficult to assess.

An alternative theoretical assessment of SAR in a seed needs the determination of

the internal E-field induced inside. While this was experimentally impossible (lack of

devices), we presumed that ½ of the incident E-field will be present in the seed, which

we estimate to be close to reality. So we took Eint

= 2V/m. In order to have a prediction

of the manner in which the E-field is attenuating through the seed, we calculated the

penetration depth at 900MHz. This gives the depth in a semi-infinite plane biological

material (in our case corn seed material) for which the internal E-field becomes 1/e (i.e.

0.368) of its value at incidence. The penetration depth (in meters) is given by:


( ) 2

1

22

]'

)"

()'

([

f

52.67

rrr

−

ε−ε+ε⋅=δ (23)

where f is expressed in MHz and εr’ = 3.8; ε

r” = 1.1 for Zea mays at f = 900MHz [4],

[5]. In this case, we obtained =δ 19cm, which shows that on the whole volume of the

seed, one can consider that the internal field is almost constant (in the semi-infinite

planar assumption). From [5] the conductivity and mass density where extracted: σ =

0.055 S/m (for f = 900MHz) and ρ = 1320kg. With these, we obtained:

kg

mW16.0SAR = (24)

2.2. Microwave Oven Exposure

In the case of short and intense exposures, SAR can be calculated from the thermal

slope of the heating curve ( )t

Taheat

Δ= and by knowing the specific heat of the

sample cs:

heatssac

t

TcSAR =

Δ= (25)

For Zea mays, cs= 1750-3690 J/kg.K [5], depending on the humidity degree of the

seed and on temperature. Form the heating curves of the seeds giving by Luxtron One

probe readings, we get aheat

= 8.5±1.5 grdC/s. The heating duration was 10s per seed.

While using a mean value of cs= 3000J/kg.K, we get:

K

kg

kJ5.45.25SAR ±=

(26)

This result is also affected by a high uncertainty, since the specific heat variation

with temperature is need to be known (and neglected here), for the experimental seed

sample that is used. In this high exposure cases, due to high temperature variations,

SAR is greatly dependent on temperature, on very short time durations. This implies a

very complicated biochemistry mechanism at the chemical reaction kinetics level. The

SAR value we get here is only order of magnitude informative and shows the

importance of refinement of dosimetric assessment.

3. Conclusion

Low level irradiation by RF electromagnetic fields of vegetal tissue for biological

effects assessment needs a sensitive dosimetric evaluation. Generally, high quality

dosimetry deserves a well-characterized exposure system and suitable methods and

techniques for SAR determination. Moreover, the vegetal samples dielectric properties

need a reliable characterization, since they highly influence both internal field level and

distribution, and temperature dependence of SAR. In present case, the dielectric


properties of the Zea mays material are influenced both by moisture content, by

frequency of used field, temperature, density and bulk density and by plant variety.

First part of the work should focus on analyzing the dielectrical parameters and needs

special devices for measuring these, since literature data is hardly available on this

issue. In our paper we used only approximate values for these parameters, as found in

literature.

In the second step, the uniformity of the incident field along the sample area

should be investigated, if possible both theoretically (simulations) and experimentally

(measurements). This step needs dedicated software for modeling-simulation of the

exposure environment and high precision, miniature E-field probes respectively, to

map the field distribution. In the case when a thermal shift may be measured in the

exposed sample, non-perturbative thermal probes are suitable. When the temperature

variation can not be detected by such an instrument, an alternative method is to be

applied for power deposition quantification. In our study, the differential power

technique was used, but since the powers are very low, comparable to the precision

level of the instruments, uncertainty is pretty high. While TEM cell offers very similar

to far-field exposure conditions (anechoic room), with a good uniformity of the field in

the exposure area, it requires sensitive devices for a reliable absorbed power evaluation

when the irradiation is non-thermal. Most of RF signals generators need amplifiers in

order to produce thermal levels of exposure. When wide band amplification is needed,

the price of the amplifiers becomes prohibitive.

A cheap variant for high power level irradiation is by using a microwave oven,

with the condition that the sample volume to be very small, so as the field non-

uniformity inside the oven to be minimized. In this case, good dosimetric results may

be obtained by using the non-perturbative fluoroptic thermal probe. However, since at

such high power levels the sample is heating extremely fast, and since the specific heat

of the sample is usually highly dependent on temperature, a precise SAR calculation is

also difficult to get, from this point of view. A heating rate of approximately 80

C/s, as

in our experimental case, needs a very rapid response of the thermal probe, in order to

gain precise results.

The precision of SAR calculation when very low or very high RF exposure

conditions are applied, needs further refinement. As for present paper, the three

methods used for SAR evaluation in non-thermal irradiation condition at 900MHz give

a standard deviation of 127%, when average SAR in the Zea mays seeds is 0.38 mW/kg.

On the other hand, in high level exposure conditions, at 2.45 GHz, SAR estimation

uncertainty is of about 72% for an average SAR of 25.5kJ/kg in Zea mays seeds.

References

[1] Radiofrequency Radiation Dosimetry Handbook, eds: C.H. Durney, H. Massoudi, M.F. Iskander, , 4th

Edition, USAFSAM-TR-85-73, Brooks AFB, Texas, USA, 7.4-7.14, 1996.

[2] M. Morega, S. Miclaus, Electromagnetic environment generated in a TEM cell for biological dosimetry

applications, ISEF 2007 – XIII International Symposium on Electromagnetic Fields in Mechatronics,

Electrical and Electronic Engineering, Prague, Czech Republic, September 13-15, 2007.

[3] M. Racuciu, S. Miclaus, UHF radiofrequency electromagnetic field influence on vegetal tissue at

molecular level, 8TH

International Congress of the European Bioelectromagnetics Association (EBEA),

Bordeaux, France, 10-13 April 2007.

[4] Asabe Standard: Dielectric Properties of Grain and Seed, Nelson S.O., et al., American Society for

Agricultural and Biological Engineers, AE D293.2, JUN1989, R - 2005.


[5] Z. Hlavacova, Utilization of electric properties of granular and powdery materials, Int. Agrophysics, 19,

(2005) 209-213.

Acknowledgement. Present work is part of a research project developed at Land Forces Academy in Sibiu,

under the Contract no. CEEX 05-D11-54/2005 granted by Romanian Ministry of Education and Research.


Non-thermal, Continuous and Modulated RF Field Effects on Vegetal Tissue

Developed from Exposed Seeds Mihaela RĂCUCIU a1, Simona MICLĂUŞ b and Dorina E. CREANGĂ c

a University “Lucian Blaga”, Sibiu, Romania b Land Forces Academy, Sibiu, Romania c University “Al. I. Cuza”, Iasi, Romania

Abstract. The present paper aims to search possible differences in effects due to low-level RF exposure to continuous wave in comparison to modulated RF field on the same carrier frequency, in vegetal tissues. This experimental study was focused on determination of some representative parameters for development of an agricultural plant species, Zea mays, whose seeds were previously exposed to non-thermal RF field in the 900MHz band, in controlled conditions. Incident low-level continuous wave, amplitude modulated and frequency modulated signals were applied, while pigments concentration of chlorophyll a, chlorophyll b, carotenoids, nucleic acid concentration and average length of the plants in the 12th day of development post-irradiation, were measured. A “thermal” reference constituted a very short duration exposure of one sample of seeds to 2.45 GHz high thermal field, while control unexposed sample was the absolute reference. The effects were different for continuous and modulated signals, but modulation has generally a lower impact in low-level exposures, and this was predictable

Keywords. RF field, vegetal tissue, photo-assimilatory pigments, nucleic acids.

Introduction

Numerous experiments proved that modulated high-level RF fields have biological effects and that modulation is an important factor [1] - [3]. Tkalec et al. [4] reported that the growth of plants exposed to continuous 900MHz electromagnetic field was significantly decreased in comparison with the control, while a modulated field at 900MHz strongly inhibited the growth in the Lemna minor, suggesting that investigated electromagnetic fields might influence plant growth.

The same researchers [5] observed that the electromagnetic field frequencies of 400 and 900MHz for 2 hours generally increased photosynthesis rate of the Chlorella kessleri algae. Also, the 400MHz frequency of the electromagnetic field decreased respiration rate while 900MHz increased it.

The germination rate and root length did not change significantly after 900MHz electromagnetic field exposure, but modulated field significantly of a longer exposure time (4 hours) increased mitotic index compared to corresponding controls in the

1 Corresponding author: University “Lucian Blaga”, Faculty of Science, Physics Dept., 5-7 Dr.I.Ratiu

St., 550024, Sibiu, Romania,; E-mail: [email protected]



142

Allium cepa seeds case [6]. Sandu et al. [7] studied the 400MHz electromagnetic field influence on the black locust (Robinia pseudoacacia) seedlings. Chlorophyll a as well as chlorophyll b level was found to decrease and chlorophyll ratio was decreasing logarithmically to the increase of daily exposure time on the electromagnetic field.

Some experimenters have reported effects that depend on amplitude modulation at low levels of RF exposure, but however the effects remain isolated to particular in vitro systems. Although a few experiments have been repeated successfully in independent laboratories, others have not, and the question of whether modulation is important for biological effects remains open.

In this respect, present paper aims to search possible differences in effects due to low-level RF exposure to continuous wave in comparison to modulated RF field on the same carrier frequency, in vegetal tissues.


The experimental work focused on determination of some representative parameters for development of an agricultural plant species, Zea mays, whose seeds were previously exposed to non-thermal RF field in the 900MHz band, in controlled conditions. Incident low-level continuous wave (CW), amplitude modulated (AM) and frequency modulated (FM) signals were applied, while pigments concentration of chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoids (Car), nucleic acid concentration (NA) and average length (AL) of the plants in the 12th day of development post-irradiation, were measured. A “thermal” reference constituted a very short duration exposure of one sample of seeds to 2.45 GHz high thermal field, while control unexposed sample was the absolute reference. Quantitative insight in the molecular mechanisms involved in the complex phenomena of plants growth was carried out by means of spectrophotometrical assays. We chose Chl a, Chl b and Car pigments as indicators, since they are photosynthetic pigments found in most plants, and their presence is a requirement for photosynthesis process. While Chl a is the main photosynthesis pigment, directly involved in the solar energy conversion into chemical energy, the Chl b and Car are the accessory pigments involved in the photosynthesis process, with a very consistent role in the sustaining of photosynthesis efficiency, by means of the absorbed energy transfer to Chl a molecules and Car pigments are anti-oxidants and efficient free-radical scavengers. Nucleic acids (NA) are directly responsible for the cell and tissue development either in photosynthetic plants or animal and microorganisms, while AL indicates the general stimulatory or inhibitory action of the electromagnetic radiation. The chlorophylls ratio (Chl a/ Chl b) is known as an indirect indicator of the energetic activity of Light Harvesting Complex II (LHC II) system that is controlling the first stage of solar energy conversion into its chemical form.

Exposure to RF field was applied to seeds only (having a rather uniform genophond), before germination process. The Petri dishes containing 70 seeds each, were exposed for 24 hours inside a TEM cell (model IFI CC-104SEXX), which was supplied from a RF signal generator (model Hameg HM 3184-3) (Figure 1). Sample no.1 received a CW of f=900 MHz, level 7dBm; sample no.2 received an AM signal (fc=900MHz, AM mod=sqrt; level 7dBm; f mod = 20 kHz); sample no.3 received an AM signal (fc=900MHz, AM mod=sqrt; level 7dBm; f mod = 10Hz); sample no.4 received an FM signal (fc=900MHz, FM mod=sqrt; level 7dBm; FM f mod = 10Hz), sample no.5 received an FM signal (fc=900MHz, FM mod=sqrt; level 7dBm; FM f

M. Racuciu et al. / Non-Thermal, Continuous and Modulated RF Field Effects 143

mod = 10Hz; gate signal). Besides low-level exposure, another sample, sample no.6 received a powerful CW signal of f=2.45 GHz inside a microwave oven, at P= 800W, for 5 seconds, with measured heating curve. Incident field in the TEM cell was uniform, at the value (rms) of Einc=2.17 V/m, i.e. a power density Sinc=0.012 W/m2. The absorbed RF power (or SAR) was both calculated and measured. For measurements, a fiber optic Luxtron One probe was used (to show lack of heating in TEM cell exposures or to measure the heating curve slope, in the case of microwave oven). For TEM cell exposures, the differential power method was applied, by using two power sensors (one of them bidirectional - by Rhode & Schwarz) connected to two spectrum analyzers (FSH 3 model, by Rhode& Schwarz).

Figure 1. Schematic figure of exposure set-up

Irradiated seeds germination occurred on porous paper support, in darkness and closed Petri dishes, environmental conditions being kept under peer control, temperature and moisture levels being 24.00C and 90% humidity respectively. After germination the young plantlets development was conducted in the same controlled laboratory conditions (t=22.0±0.50C, illumination -10h: 14h light/dark cycle and 70% humidity) and the culture medium of young plantlets was daily supplied with the same amount of deionized water.

Plant individual length of the 12 days plantlets old was measured and germination percentage was determined as well. The average lengths and the standard deviations were calculated for each batch of seeds. For both RF field exposed samples and controls, the biological material was harvested from the entire green tissue mass obtained by mixing up all plantlets grown within a Petri dish. For spectrophotometric measurements a CINTRA 5 spectrophotometer UV-VIS provided with quartz cells was used. After 12 days of plants growth, the assay of the assimilatory pigments extracts in 80% acetone was performed following the Lichtenthaler & Welburn’s method [8], while the assay of nucleic acids level accordingly to a modified Spirin’s method [9-10] was carried out: spectrophotometric measurements were performed at the wavelengths of: 663nm, 646nm and 470nm (versus acetone 80%) for the assay of chlorophylls

M. Racuciu et al. / Non-Thermal, Continuous and Modulated RF Field Effects144

(Chla, Chlb) and carotenoids pigments (Car) from green tissues and respectively at 260nm and 280nm (versus perchloric acid 6%) in the case of nucleic acids.

For the calculation of photosynthetic pigments the Eqs. (1), (2) and (3) were applied while in the case of nucleic acids calibration curves (based on the spectral readings to the mentioned wavelengths).

( )wd

VE81.2E21.12)g/g(Chla 646663⋅

⋅−⋅=μ (1)

( )

wdVE03.5E13.20)g/g(Chlb 663646⋅

⋅−⋅=μ (2)

wd227V)Chlb104Chla27.3E100()g/g(Car 470

⋅⋅⋅−⋅−⋅=μ (3)

where w is the fresh vegetal sample mass, V is the extract volume (in 80% acetone),

λE is the light extinction to the wavelength λ and d is the quartz cell width. Statistic analysis of the experimental data resulted from the three repetitions of the

spectrophotometrical analysis, was accomplished by means of ANOVA test - applied using MsExcell soft package - to evaluate reliability of modifications induced by RF field into the exposed samples in comparison to the control ones as well as among the samples corresponding to different exposure, considering the significance criterion of 0.05.

2. Results and Discussions

Theoretical and experimental dosimetry indicated that in the case of non-thermal exposures in the TEM cell, SARlow<1mW/kg for all exposures, while in the 2.45GHz oven, SARhigh = 2.6kW/kg.

The average lengths of Zea mays plantlets and afferent standard deviations were calculated for each batch of test seeds (Figure 2). The confidence interval was calculated for every batch of plantlets using the Student test, for the confidence level P=90%. Average length of plants showed statistically significant differences: CW exposure seems to stimulate development, while modulated field exposure seems to suppress it, compared to control. Only sample no. 3 showed no difference compared to control. The 2.45GHz short thermal exposure showed no length-of-plant difference to control.

Since among the biochemical factors that determine the plant growth the nucleic acids and the chlorophylls are the most involved in the early ontogenetic stages further discussion was focused on the corresponding experimental data extracted during the experiment. Though strongly determined by the cell genetic information (stored within the nucleic acids), the cell and tissue development depends on the cell divisibility and the photosynthesis efficiency. The data from Figure 3 present the situation of the photosynthetic pigments that play very important role in solar light conversion toward chemical energy stored within organic compounds accumulated in the vegetal organism. Chlorophylls (Chl a, Chl b) and carotenoids (Car) contents showed only slight


variations between all samples and it seems they cannot to be connected either to frequency, or to modulation, or to thermal or non-thermal effects.

Average lengths, 12th day, P=90%

0

20

40

60

80

100

120

140

M S1 S2 S3 S4 S5 S6Experimental sample

L, m

m

Figure 2. The average length of plants provided irradiated seeds of Zea mays

0

10

20

30

40

50

60

70

80

M S1 S2 S3 S4 S5 S6

Experimental sample

Chl

a, C

hl b

, Car

(mg/

g )

Chl a Chl b Car

Figure 3. Assimilatory pigments level in Zea mays plantlets provided irradiated seeds versus UHF-CW exposure time (Chl a –the content of chlorophyll a, Chl b – the content of chlorophyll b, Car – the content of total carotenoid pigments).

The chlorophylls ratio being considered an important physiological parameter regarding the photosynthesis efficiency, being generally accepted that this parameter is an indirect indication on the response of the Light Harvesting Complex II from the chloroplast membranes, where photosynthesis is located, the results displayed in Figure 4 might be taken as a premise upon the slight inhibitory effect of the photosynthesis in


the case of CW exposure and the short thermal exposure (with statistic significance related to the significance threshold of 0.05).

0

0.5

1

1.5

2

2.5

3

3.5


Chl

a/ C

hl b

Figure 4. Electromagnetic field effects on the chlorophylls ratio in Zea mays plantlets provided by irradiated seeds

Nucleic acids (DNA+RNA) concentrations were most affected by exposure

(Figure 5), but in an unpredictable manner.

0

100

200

300

400

500

600

700


AN

(mic

rog/

g)

Figure 5. The level of DNA and RNA for the plantlets provided by electromagnetic field irradiated seeds

The only sample not influenced, from this point of view, was again sample no.3, as compared to control. The most inhibiting effect was observed in the 2.45GHz thermal exposure, while the most stimulating one was observed in the CW exposure and then in


the AM exposure of sample no. 2 (with statistic significance related to the significance threshold of 0.05). The nucleic acids are directly responsible for the cell and tissue development either in photosynthetic plants or animal and microorganisms.

Though the electromagnetic energy of the absorbed photons is of many orders of magnitude smaller than that needed to break down chemical bonds within the molecules of chlorophyll of nucleic acid however their electromagnetic energy could trigger complex synergetic cellular mechanisms that finally can lead to the plant growth disturbing.

3. Conclusions

Obtained results showed that investigated electromagnetic fields could influence important processes in plants (e.g. photosynthesis) upon plants during their early ontogenetic stages. Non-thermal effects of RF are observable in plant development and at the nucleic acids content level. CW exposure for 24h shows the most important effect. The effects were different for CW and modulated signals, but modulation has generally a lower impact in low-level exposures, and this was predictable. However, one should also consider that artifacts are hard to recognize and eliminate, temperature control is essential and RF field effects could not exclude all possible confounding factors.

References

[1] Workshop: Biological and Biophysical Research at Extremely Low- and Radio Frequencies: (1) Application of Research Results across the Frequencies and Modulation Schemes of Present and Future Wireless Technologies, and (2) Demodulation in Biological Systems”, Bad Münstereifel, Germany, 4-5 December, 2000.

[2] Seminar of MMF — Mobile Manufacturers Forum: “Mechanisms for Interactions of Radiofrequency Energy with Biological Systems: Principal Conclusions” Washington, DC, 23 July, 2001.

[3] I. Belyaev, Non-thermal biological effects of microwaves: current knowledge, further perspective and urgent needs, COST 281 Workshop: ''Do sinusoidal versus non-sinusoidal waveforms make a difference?'' Zurich, February 17th - 18th, 2005.

[4] M. Tkalec, K. Malaric, B. Pevalek-Kozlina, Influence of 400, 900, and 1900 MHz electromagnetic fields on Lemna minor growth and peroxidase activity, Bioelectromagnetics, 26(3) (2005), 185-193.

[5] M. Tkalec, K. Malarić, R. Malarić, I. Leniček, B. Pevalek-Kozlina, Effect of electromagnetic fields on photosynthesis, 3rd International workshop on biological effects of electromagnetic fields, Kos, Greece, 4- 8 October 2004.

[6] M. Tkalec, Z. Vidakovic-Cifrek, B.Pevalek-Kozlina, Evaluation of the Genotoxic Potential of Microwave Electromagnetic Fields in Onion (Allium Cepa), IEEE International Symposium on electromagnetic compatibility (EMC2007), Supplement to EMC Newsletter, Hawaii (2007) 44.

[7] D. D. Sandu, C. Goiceanu, A. Ispas, I. Creanga, S. Miclaus, D.E. Creanga, A preliminary study on ultra high frequency electromagnetic fields effect on black locust chlorophylls, Acta Biologica Hungarica, 56 (1/2) (2005 ), 109-117.

[8] H. K. Lichtenthaler, A. R. Wellburn, Determinations of total carotenoids and chlorophylls a and b of leaf extracts in different solvents, Biochemical Society Transactions, 11 (1983), 591 – 592.

[9] V. A. Struchkov, N. B. Strazhevskaya, R. I. Zhdanov, DNA-bound lipids of normal and tumor cells: retrospective and outlooks for functional genomics, Bioelectrochemistry, 58 (2002), 23–30.

[10] R. I. Zhdanov, N. B. Strazhevskaya, A. R. Jdanov, G. Bischoff, A spectroscopic and surface plasmon resonance study of oleic acid/DNA complexes, J. Biomol. Struct. Dyn., 20 (2002), 231–241.


Chapter 4

Computer Simulation in Bioelectromagnetics

Three-dimensional Modelling of Extremely Low Frequency Thin Conducting Screens

Piergiorgio ALOTTO, Massimo GUARNIERI, Federico MORO1 and Roberto TURRI Dipartimento di Ingegneria Elettrica, Università di Padova

Via Gradenigo 6/a, 35131 Padova, Italy

Abstract. A novel three-dimensional integral method is used in order to assess the effectiveness of thin conducting screens for reducing stray magnetic fields. Integral formulations are particularly suited for shielding problems, as computing costs are reduced compared to commercial codes, relying mainly on the Finite Element Method. A conducting screen for a MV/LV substation is designed by means of the developed code. Measured and computed values of the rms magnetic flux density in proximity of the substation are compared in order to test the accuracy and the reliability of the numerical analysis.

Keywords. Magnetic field, Electromagnetic Compatibility, Extremely Low Frequency, MV/LV substations, shielding, eddy currents, conducting materials.

Introduction

Due to increasing concerns about human exposure to electromagnetic fields, the reduction of stray fields in proximity of MV/LV substations has become of great importance. Metallic shields made up of thin conducting plates often represent a more viable solution than rearranging the layout of electric devices inside the installation [1]. Electromagnetic analysis software is based mainly on the Finite Element Method (FEM), which is typically demanding when analysing thin structures embedded in large air regions [2]. An accurate analysis of the shield performance implies numerical techniques capable of modelling properly both ELF sources and thin plates. Several methods have been proposed in the literature to cope with these requirements. Most of them are based on two-dimensional (2D) electromagnetic formulations, which provide preliminary information at the design stage [3]. Three-dimensional (3D) approaches should be used instead in order to assess confidently the shield effectiveness.

The main aim of the present work is to show how the three-dimensional integral method presented in [4] can be used successfully for accurate simulations of the shielding performance, overcoming the several limitations encountered in CAD/CAE commercial software.

1 Corresponding Author: Federico Moro, Dipartimento di Ingegneria Elettrica, Università di Padova, Via Gradenigo, 6/A, 35131 Padova; E-mail: [email protected].


151

Conducting shield design for a 20/0.4 kV substation

In low frequency magnetic shielding (3-300 Hz) the critical factor in designing a cost-effective shield is to minimize the amount of material in order to achieve a specific field attenuation level. The shield performance is typically characterised by the so-called shielding factor SF, i.e. the ratio SF=Bi/Bo between the rms values of the shielded magnetic flux density, Bi, and the unshielded one, Bo. Once the basic goal of the shielding problem has been defined, there are a number of basic design considerations that impact the shield cost-effectiveness [3, 5]:

• the shield efficiency depends almost linearly on its thickness for highly conducting metals;

• the intensity of induced currents depends on the shield extension, less on its thickness;

• the shielding performance increases as the distance between shield and sources reduces;

• conducting plates compensate mainly the normal component of the impressed field, thus source orientation turns out to be a major factor in determining the shield effectiveness.

In order to tackle properly shielding problem complexity, an original three-dimensional integral method, such that proposed in [4], was developed and applied here to design a conducting shield for a 20/0.4 kV indoor substation. The aim of the intervention was to reduce the field intensity in the room above the substation. Preliminary measurements showed exposure levels of the order of 3-4 μT at floor level and 1-2 μT at 1 m height, much more beyond the exposure limit fixed by Italian standards [6].

A plane view of the substation is shown in Figure 1. The main magnetic field sources are indicated in the inset. Two transformer units (630 kVA, 6% short circuit voltage), placed 1.70 m apart, are connected in parallel; LV feeders, placed 0.1 m aside and 2 m long, drive balanced three-phase currents (200 A rms, 50 Hz frequency).

MV board

LV board

0.30 m

Filter capacitor bank

0.60 m

3.50 m

0.8 m

2.50 m

0.40 m 4.80 m 3.80 m

TR2

TR1

1.07 m

0.50 m

3.50 m

3.00 m 0.80 m

1.05 m

0.70 m

1.90 m

0.80 m

0.30 m

1.80 m LV cables yz

Figure 1. Plane view of the substation (the yz plane for field computing is indicated in dashed line).

P. Alotto et al. / 3D Modelling of Extremely Low Frequency Thin Conducting Screens152

The most intense field sources are the LV conductors (cables and bus-bars) and the MV/LV transformers, since they drive the highest currents in the installation; the effect of other magnetic field sources in the substation can be neglected.

The effect of MV/LV transformers (Figure 2) was examined by 3D analysis, where windings are modelled as one-turn coils with current intensity proportional to the stray linkage. The integral method was used to design a metallic screen to be installed above the transformers, while 2D FEM was used to design a shielding enclosure to be put around the power cables feeding the LV board. The shield performance was evaluated by using the shielding factor defined above.

Figure 2. Model of the shielding apparatus for the indoor substation.

Different shield configurations were analysed by the 3D integral code and by the

2D FEM code in order to identify the best shielding solutions, a trade-off between intervention costs and required attenuation levels. The most economical solution for shielding the transformers was found to be a 2 mm thick copper plate (3 m wide, 3.5 m long), placed 0.12 m above the feeders. Simulations showed that the U-shaped shield provided attenuation levels similar to the flat configuration (with the latter solution having significantly smaller material and installation costs). The shielding factor was mapped on the vertical plane yz, shown in dashed line in Figure 1, in order to evaluate the screen efficiency at different heights. Figure 3 shows that the field intensity level is reduced uniformly up to 50 % in the shielded room for s2>3 m. It is shown that the magnetic field reduction is uniformly distributed, according to design requirements.

As regards the LV cables feeding the board, a considerable field reduction was obtained by using a 2 mm copper shield (2.5 m long, 0.4 m wide) enclosing the cable trunking and by using an optimized layout of phase conductors (the so-called trefoil arrangement).

P. Alotto et al. / 3D Modelling of Extremely Low Frequency Thin Conducting Screens 153

Figure 3. Shielding factor on the plane yz.

The magnetic shield simulated by the integral method was built by welding two 1.75 m x 3 m wide, 2 mm thick copper plates, installed as shown in Figure 4. In order to test the reliability of the developed procedure computed field rms values were compared with those measured on the same positions. These values were measured along lines, located 0.2 m and 0.8 m above the floor of the shielded room, on the vertical plane yz depicted in Figure 1.

Figure 5 and Figure 6 show that computed and measured field intensity values at different heights are in good agreement. In that case uncertainties on computed values depend mainly on the approximation in estimating current loads and locations of electric devices inside the substation. The actual attenuation level provided by the magnetic shield, almost uniformly distributed, is about 60 %.

Figure 4. Magnetic shield installed above the MV/LV transformers.


0 2 4 6 8 10 12 14 160

0.5

1

1.5

2

2.5

3

3.5

4

4.5x 10

-6

s [m]

mod

(B) [

T]

BRMS con schermo

BRMS senza schermo

BRMS misurato

0 2 4 6 8 10 12 14 160

0.5

1

1.5

2

2.5

3

3.5

4

4.5x 10

-6

s [m]

mod

(B) [

T]

BRMS con schermo

BRMS senza schermo

BRMS misuratoUVW

UVW

0 2 4 6 8 10 12 14 160

0.5

1

1.5

2

2.5

3

3.5

4

4.5x 10

-6

s [m]

mod

(B) [

T]

BRMS con schermo

BRMS senza schermo

BRMS misurato

0 2 4 6 8 10 12 14 160

0.5

1

1.5

2

2.5

3

3.5

4

4.5x 10

-6

s [m]

mod

(B) [

T]

BRMS con schermo

BRMS senza schermo

BRMS misuratoUVW

UVW

UVW

UVW

Figure 5. Measured and computed field rms values at 0.20 m height above the floor.

UVW

UVW

UVW

UVW

UVW

UVW

Figure 6. Measured and computed field rms values at 0.80 m height above the floor.

Conclusion

A novel integral procedure has been used successfully to analyse the effectiveness of conducting laminations for industrial shielding applications. By using the developed approach the intrinsic complexity of shielding problems can be accounted for much more easily. Besides, the duration of the design process can be significantly reduced.

P. Alotto et al. / 3D Modelling of Extremely Low Frequency Thin Conducting Screens 155

The integral procedure has been used to design a metallic shield to be installed inside a MV/LV substation. Field reduction targets have been addressed properly, despite the complexity of the modelled system. Comparisons between experimental and computed results have shown that the proposed method is both fast and accurate.

References

[1] O. Bottauscio et al., Some considerations about environmental ELF magnetic field reduction, Proc. of the 8th International IGTE Symposium, Graz (AU), pp. 275-280, 1998.

[2] L. Hasselgreen, E. Moller, Y. Hamnerius, Calculation of magnetic shielding of a substation at power frequency using FEM, IEEE Trans. on Power Delivery, vol. 9, pp. 1398-1405, July 1994.

[3] A. Canova, A. Manzin, M. Tartaglia, Evaluation of different analytical and semi-analytical methods for the design of ELF magnetic field shields, IEEE Trans. on Industrial Applications, vol. 38, pp. 788-796, May/June 2002.

[4] P. Alotto, M. Guarnieri, F. Moro, A boundary integral formulation on unstructured dual grids for eddy current analysis in thin shields, IEEE Trans. on Magnetics, vol.43, pp. 1173-1176, April 2007.

[5] Lin Xu, Yaping Du, Zhengcai Fu., Magnetic shielding by large metallic structure in modern buildings, Proc. of 3rd International Symposium on EMC, 58, 755-758, 2002.

[6] DPCM 8 Luglio 2003, Fissazione dei limiti di esposizione, dei valori di attenzione e degli obiettivi di qualità per la protezione della popolazione dalle esposizioni ai campi elettrici e magnetici alla frequenza di rete (50 Hz) generati dagli elettrodotti, Gazzetta Ufficiale, n. 200, 29-8-2003 (in italian).


The Influence of Shape of the Body on

SAR Coefficient in the Biological Object

Katarzyna CIOSK a, 1

, Andrzej KRAWCZYK b, 2

a

Kielce University of Technology, Poland

b

Central Institute for Labour Protection, Department of Bioelectromagnetics, Poland

Abstract. The paper presents results of SAR (Specific Absorption Rate)

calculations in different spheroid biological objects. The aim of the study was to

trace the influence of body geometry on the value of the whole-body SAR. The

biological model that has been taken into account is a prolate spheroid. The

spheroid is an isotropic lossy dielectric. The mass of the bodies were taken was

constant. The external medium was assumed to be free space and the excitation as

a uniform plane wave. The calculations were carried out for two cases of

polarization. The simulations were done at 900 MHz and 1800 MHz frequency.

The values of the SAR were calculated based on the calculating of the electric

field strength distribution inside the body using semi-analytical method.

Keywords. SAR, electromagnetic field, biological object, spheroid

Introduction

The wireless technology relies upon an extensive network of base stations, relaying

information with radiofrequency (RF) signals. Cellular communication systems require

the use of many base stations located throughout a service area and it is necessary to

install antenas on residential and public buildings. The growth in wireless mobile

communications has created public concern about the health effects of organism

exposed to electromagnetic field from the base station antennas. An important

motivation for researchers is to gain a detailed understanding of the power absorption

inside the body. For assessing exposure from transmitters, the most useful quantity is

SAR (Specific Absorption Rate). SAR calculations or measurements can be used for

accurate human exposure assessment in close proximity to base station antennas.

1

Katarzyna Ciosk, Kielce University of Technology, Al. 1000 lecia P.P. 7, 25-314 Kielce, Poland, E-mail:

[email protected]

2

Andrzej Krawczyk, Central Institute for Labour Protection, Department of

Bioelectromagnetics,Warsaw,Poland, E-mail: [email protected], ul. Czerniakowska 16, 00-701 Warszawa,

Poland, E-mail: [email protected]


157

The SAR describes the energy absorbed by biological object. This parameter is the

quantity which determines the thermal effect in the biological tissue subjected to the

electromagnetic field. And thus, it is possible to determine electromagnetic hazard

coming from various sources, both industrial and environmental. SAR takes into

account the incident field parameters and also geometry and electrical properties of the

body subjected to electromagnetic field. The SAR gives much more important

information about exposure conditions than the electric parameters of electromagnetic

field such electric field strength, magnetic field strength or power density. That is why,

the calculation of the SAR becomes a target for many computational centers [1], [2].

The SAR has been introduced as the basis for ANSI excposure standard [3]. The

whole-body SAR is defined by

M

dVP

SAR

V

V

WB

∫∫∫

= (1)

where: PV

– density of power absorbed in the body [W/m3

], M – mass of the body [kg].

Value of SAR depends on the incident field parameters such the intensity, polarization

[4] and frequency [5]. The absorption of electromagnetic wave depends also on

parameters of object such as size, shape and orientation. SAR is higher when the body

is more perpendicular than parallel to an incident field. It is also higher when the cross

section of the body perpendicular to the incident magnetic field is larger.

This paper aims at finding how SAR distribution depends on the shape of object.

The biological model that has been taken into account is a prolate spheroid. The mass

of object was assumed as constant. The simulations were done at GSM frequencies 900

MHz and 1800 MHz using semi-analytical method. Geometry of the spheroid body is

determined by ratio h :

l

a

h = (2)

where a is major axis and l is minor axis of spheroid as shown in Figure1 .

l

Figure 1. Schematic diagram of spheroid model

K. Ciosk and A. Krawczyk / The Influence of Shape of the Body on SAR Coefficient158

Method of Calculations

To trace the influence of body geometry on the value of the whole-body SAR the

calculation was made. The values of the SAR were calculated based on the calculating

of the electric field strength distribution inside the body. The model as a prolate

spheroid with major axis l , minor axis a is shown in Fig.1. The spheroid is an isotropic

lossy dielectric. The spheroid body mass was assumed as constant. The relative

permittivity ε’-jε” and the conductivity of tissue depend on frequency [6]. European

Standard EN-50361 [7] establishes values of ε, γ for phantom liquid at mobile

frequency band 300 – 3000MHz to be used in SAR calculations. The simulations were

done for GSM frequencies used in mobile telephony: 900 MHz and 1800 MHz. The

external medium is assumed to be free space. Time-harmonic fields with the time-

dependence ejωt

as a uniform plane wave are suppressed. The rms value of the electric

field strength incident was 61,4 V/m. The calculations were carried out for two cases of

polarization. At polarization E the long axis of the body is parallel to the electric field

vector while at polarisation H the long axis of the object is parallel to the magnetic

field vector. The values of the SAR were calculated using semi-analytical method. The

method of calculations at polarisation H was described in [8] and the method of

calculations at polarisation E was described in [9]. The electromagnetic field is

described by Maxwell’s equations and they were solved by semi-analytical method

solution of the problem. The method enables investigating of the internal structure of

the coefficient. The correctness of this method has been verified by an experiment

made on spheroid phantom [9]. The spheroid object was filled up the phantom,

corresponding to biological tissues in accordance with European standard CENELEC

for phantoms subjected to the GSM-frequency electromagnetic radiation. The method

requires a short calculation time and a small PC memory. It is possible to trace the

influence of different parameters of object as well as electromagnetic parameters of

field, such as frequency and polarization on the value of SAR. The relative complex

permittivity data is compiled from [6].

Calculation Results

To demonstrate the influence of the shape of the body on SAR the computations was

made. The mass of the bodies were taken was constant M = 20g.The major axis and

minor axis of the spheroid were corresponding to ratio h (2). The calculations were

carried out for two frequencies 900 MHz and 1800 MHz and two cases of polarization.

Figure 2 shows the distributions of the SAR at polarization H. The value of SAR grows

with ratio h and is grater at polarization E than that of polarization H. In Figure 3 are

shown the results of calculations of the SAR at polarization E. For E polarization SAR

increases as an object becomes longer and thinner, and decreases as it becomes shorter

and fatter. SAR is higher when the body is more perpendicular than parallel to an

incident field. It is also higher when the cross section of the body perpendicular to the

incident magnetic field is larger.

K. Ciosk and A. Krawczyk / The Influence of Shape of the Body on SAR Coefficient 159

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

SA

R

[W/k

g]

h

1800 MHz

900 MHz

Figure 2. Distribution of SAR at polarisation H

0.3 0.4 0.5 0.6 0.7 0.80

0.2

0.4

0.6

0.8

1

h

SA

R [

W/k

g]

900MHz

1800MHz

Figure 3. Distribution of SAR at polarisation E

Conclusions

The SAR distribution in the spheroid biological model is treated by employing semi-

analytical techniques. The calculation result has been presented for frequencies

900MHz and 1800 MHz and two polarizations. According to the result we can find out

that SAR depends on geometry of the body. It is thus crucial to take into account the

body size and parameters of the external field to establish relationships between

K. Ciosk and A. Krawczyk / The Influence of Shape of the Body on SAR Coefficient160

biological effects that occur in lab animals and the corresponding effects that might

occur in humans at a given incident field.

References

[1] C. H. Durney, D. A Christensen: Basic Introduction to Bioelectromagnetics, CRC Press 2000.

[2] C. Furse, S. Hagness, U. Jakobus (eds): ACES Journal, Special Issue on Computational

Bioelectromagnetics, vol. 16, no.1, 2001.

[3] American National Standards Institute 95.1 Safety levels with respect to human exposure to radio

frequency electromagnetic fields, 300 kHz to 100 GHz, Institute of Electrical and Electronics

Engineering, New York 1982.

[4] Ciosk K., Krawczyk A., Kubacki R.: The influence of the electromagnetic wave parameters on SAR

coefficient ISEF’05-International Symposium, September 2005, Baiona, Spain.

[5] Ciosk K., Krawczyk A: The influence of the electromagnetic wave frequency on SAR in biological

object., EHE’06, Madeira, pp.2.97-2.100.

[6] R. Kubacki at al., Comparison of Numerical and Measurement Methods of SAR of Ellipsoidal

Phantoms with Muscle Tissue Electrical Parameters, ISEF’05- International Symposium September

2005, Baiona, Spain

[7] European Standard –EN50361, Basic standard for measurement of Specific Absorption Rate related to

human exposure to electromagnetic fields from mobile phones (300MHz-3GHz) CENELEC July 2001.

[8] Ciosk K. at al., On SAR evaluation in the model of human head subjected to radiofrequency

electromagnetic field, w: Electromagnetic fields in electrical engineering (ed. A. Krawczyk i S. Wiak),

IOS Press, Amsterdam 2002.

[9] Ciosk, A. Krawczyk, R. Kubacki, The comparison of phantom model and simulation results in SAR

analysis, in: Computer Engineering in Applied Electromagnetism (ed. S. Wiak, A. Krawczyk, M.

Trlep), Springer, 2005.

K. Ciosk and A. Krawczyk / The Influence of Shape of the Body on SAR Coefficient 161

A Transmission Line Scale Model

for Characterizing Electric

and Magnetic Fields

Jaime ESTACIO a

, Adolfo ESCOBAR a,1

, Guillermo APONTE a

,

Héctor CADAVID a

a

Grupo de Investigación en Alta Tensión, Universidad del Valle, Colombia

Abstract. A high-voltage transmission-line scale model can be used as a design

tool to determine both the electric and magnetic field distribution around the line.

A scale model allows to evaluate changes in phase arrangement and current

variations, and to assess the different mitigation techniques to reduce the electric

and magnetic field levels. In this paper, the development and construction of a

115-kV transmission-line scale model is presented. The experimental results were

compared with calculated values, showing a good agreement.

Keywords. Transmission line, electric and magnetic fields, scale model.

Introduction

Electric power transmission and distribution lines have been in use for about 100 years.

Since 1970, the concern about that the electric and magnetic fields from power lines

and other sources could affect the health of exposed individuals has been increased.

Prior to 1982, electric fields were the main concern; but with the publication of one

paper by Wertheimer and Leeper [1], and the subsequent appearance of papers from

other sources, serious concerns have developed about magnetic field exposure.

Public concern about fields emitted from transmission lines has resulted in

significant opposition to the construction and upgrading of new power transmission

facilities. Also, ground level electric and magnetic fields from overhead transmission

lines are critical parameters for considering in the right of way specification. Electric

and magnetic fields around power transmission lines have been assessed before [2, 3].

However, precise calculation of these fields distribution under power lines is of great

importance [4, 5] and should be elaborated on.

Both the electric and magnetic fields produced by transmission lines present

special characteristics. These fields are affected by power system conditions (voltage

and current), phase arrangement, line height, and phase spacing. Therefore, it is

difficult to characterize the field distribution when one or several parameters have

changed. To evaluate both the electric and magnetic field distribution, a transmission-

line scale model was designed and built. The scale model allows to modify the

geometric and operating conditions, and to assess mitigation techniques.

1

Corresponding Author: Adolfo Escobar, Grupo de Investigación en Alta Tensión GRALTA, Universidad

del Valle, Calle 13 No. 100-00, Edificio 356, Cali, Colombia; E-mail: [email protected]



162

1. Development of the Transmission Line Scale Model

To investigate the electric and magnetic field distribution, it is useful to use a scale

model of power transmission line because of different advantages. The scale model:

• Permits the data acquisition in a wide area and in locations where it would be

impossible to measure in real power transmission line.

• Could be used to accumulate large amounts of test data in a short time.

• Can be used as a design tool in the development stage.

• Allows easily change the line-operating and geometric conditions.

• Is useful to assess physically any event in the line.

One of the most important factors at the moment of choosing a suitable scale is the

measurement process in the model; if a very-small scale model is used, additional

measurement elements could be necessary and these elements could influence the

results. Other factor is that the transmission tower scale model should allow variations

in phase height and spacing; if the model is small, these variations will be almost

imperceptible at the moment of evaluating the field distribution.

According to the geometric characteristics of a typical 115-kV transmission line in

the Colombian electric system, it was decided to use a scale factor of 1:20. This factor

was determined by the tower height and the measurement area to be evaluated. In

accordance with this, the scale-model tower height was about 1.7 meters (see Figure 1).

In the same way, the voltage and current levels to supply the transmission-line scale

model were reduced to 1/20 in scale.

Figure 1. 115-kV transmission-line scale model

J. Estacio et al. / A Transmission Line Scale Model 163

1.1. Design Characteristics

The structure of the scale-model transmission towers was made of steel. This material

is similar to the used in the real transmission towers. The structure has holes in the

sides, spaced each 2-cm, to allow vary the line height between 0.7 and 1.4 meters

(corresponding to 14 and 28 meters for real power transmission lines).

Also, the structure has T-shape arms to set the insulators that support the

conductors. These arms, same as the structure, has holes but spaced each 1-cm to allow

vary the phase spacing between 0.35 and 0.25 meters. The insulators were made of

wood and 1.5-mm diameter steel wires were used for the conductors (see Figure 2).

1.2. Experimental Setup

Figure 3 illustrates the experimental setup for electric field tests using the transmission-

line scale model. A variable three-phase source was connected to the low voltage side

of a three-phase distribution transformer (13200/240 V). The source voltage was set to

obtain 5.75 kV at the high voltage side of the transformer. This voltage was used to

energize the scale model conductors.

Holes to vary the

phase spacing

Holes to vary

the line height

Insulator T-shape arm

Figure 2. Structure of the scale model

Three-phase

source

Three-phase

distribution

transformer

5 cm

Measurement height

Figure 3. Experimental setup for electric field tests

J. Estacio et al. / A Transmission Line Scale Model164

For the magnetic field tests, it was used a variable three-phase source to supply a load

located at the end of the transmission line (see Figure 4). The source voltage was set to

obtain 5.0-A current flowing through each conductor, which corresponds to 100 A for

real power transmission lines.

1.3. Scale Model Tests

The tower’s design allowed to implement three different conductor configurations:

double-circuit vertical, delta, and flat (see Figure 5). The first one is the most used

configuration in transmission lines in the Colombian electric system. Also, with this

scale model, it can be evaluated line-height and phase-spacing variations each two

centimeters.

Three-phase

source Load

5 cm

Measurement height

Figure 4. Experimental setup for magnetic field tests

a) Double-circuit vertical b) Delta c) Flat

Figure 5. Conductor configurations evaluated


A magnetic field meter with three orthogonal coils was used for the measurement

of ground level magnetic field. To measure the electric field strength, a parallel plate

probe was used. Both, the magnetic field meter and the electric field probe have 3%

accuracy. As the electric and magnetic field under real power lines should be measured

at a height of 1 m above ground level [6], in the scale model the lateral profile of

electric and magnetic field was measured at midspan at a 5-cm height (see Figure 6).

2. Scale Model Validation

To validate the scale model, different tests were carried out for the three configurations.

The results of these tests were compared with calculated values obtained from a

simulation program developed previously [7]. Comparison between measured and

calculated values shows that the agreement is good: the error was below 10% for

electric and magnetic field. In Figure 7 the comparison between the measurement

values obtained from the scale model and the calculated values from computation, for

double-circuit vertical and delta configurations, is showed.

3. Conclusions

A 115-kV transmission line scale model was designed and built to evaluate both the

electric and magnetic field distribution. The scale model allows to evaluate geometric

changes in the line configuration, and phase arrangement. Comparison between electric

and magnetic field measurements carried out in the scale model and calculated values

by a computer program, shows a good agreement.

Also, the scale model allows to assess the electric and magnetic field level,

obtained by applying different mitigation techniques, before to be implemented in the

transmission line. This model can be used for electric utilities before constructing a

transmission line.

Figure 6. Measurement area

J. Estacio et al. / A Transmission Line Scale Model166

0.000

0.400

0.800

1.200

1.600

-1.5 -1 -0.5 0 0.5 1 1.5

Distance (m)

Electric field

(k

V/m

)

Calculated Measured

0.0

7.0

14.0

21.0

-1.5 -1 -0.5 0 0.5 1 1.5

Distance (m)

Magn

etic field

(m

G)

Calculated Measured

a) Double-circuit vertical configuration b) Delta configuration

Figure 7. Comparison of measured (scale-model) and calculated field distribution

Acknowledgements

The authors thank to the Instituto Colombiano para el Desarrollo de la Ciencia y la

Tecnología "Francisco José de Caldas" – COLCIENCIAS for the financial support.

References

[1] N. Wertheimer, and E. Leeper, Electrical Wiring Configurations and Childhood Cancer. American

Journal of Epidemiology, 119:273-284, 1979.

[2] R. G. Olsen, and P. S. Wong, Characteristics of Low Frequency Electric and Magnetic Fields in the

Vicinity of Electric Power Lines, IEEE Trans. on Power Delivery, Vol. 7, No. 4, October 1992.

[3] M. Shimizu, T. Nagae, N. Hayakawa, M. Hikita, H. Okubo, Measurement of Magnetic Field

Distribution around Power Transmission Lines using Reduced scale-Model, ISH’97, Canada, 1997.

[4] G. Filippopoulos, and D. Tsanakas, Analytical Calculation of the Magnetic Field. IEEE Trans. on

Power Delivery, Vol. 20, No. 2, April 2005.

[5] Y. Liu, and L. E. Zaffanella, Calculation of Electric Field and Audible Noise from Transmission Lines

with Non-Parallel Conductors, IEEE Trans. on Power Delivery, Vol. 11, No. 3, pp. 1492 - 1496.

July 1996.

[6] IEEE Std. 644-1994. IEEE Procedures for Measurements of Power Frequency Electric and Magnetic

Field from A.C Power Lines. The Institute of Electrical and Electronic Engineer, Inc. New York, 1995.

[7] J. L. Estacio, Mitigación de Campos Eléctricos y Magnéticos de Baja Frecuencia en Líneas de

Transmisión, Undergraduated project, Universidad del Valle, 2006.


Reducing Computational Time in Obtaining 3D Magnetic Field

Distributions Emanated from Very High Voltage Power Lines

Carlos LEMOS ANTUNES a, b, d, 1, José CECÍLIO b, Hugo VALENTE c aElectrical Engineering Dept,University of Coimbra, Coimbra, Portugal

bAPDEE – Assoc. Port. Prom. Desenv. Eng. Electrotécnica, Coimbra, Portugal cREN – Rede Eléctrica Nacional, Lisboa, Portugal

dCASE – Centro de Accionamentos e Sistemas Eléctricos

Abstract. In this paper it is presented an algorithm to reduce the computational time to obtain the magnetic field distribution in a plane of analysis due to Very High Voltage Power Lines. It is used a two dimensional interpolation based on a spline function using as known nodal values, the field solution at nodes of a coarser plan grid.

Keywords. LMAT_SIMAG, LMAT_SIMX, High Voltage Power Lines (HVPLs), two dimensional interpolation

Introduction

The LMAT_SIMAG [1] is a software program that calculates the 3D magnetic field distribution on specified nodes, emanating from general 3D Line(s) configurations. The conductors are considered filamentary wires of arbitrary path and the catenary is approximated by straight lineal segments. The magnetic field can be calculated along any path or on any plane. The grid discretization of the solution plane is very important to obtain a good or smoother solution for magnetic field distribution which may lead to a considerable computational time. To reduce this computational time, we have used a two dimensional interpolation function to estimate the field solution at intermediate nodes, from the field solution obtained in a coarser plane grid.

1. Formulation

It was used a two dimensional interpolation function [2-3] to estimate the intermediate values from two known values. The interpolation is essential to obtain a smoother or good representation of magnetic field distribution, between two known field values. _________________________

1 Corresponding Author: Lab. CAD/CAE, Electrical Engineering Dept, University of Coimbra, Pólo II, 3030 – 290 Coimbra, Portugal; e-mail: [email protected].



168

Given a rectangular grid xk, yl and the associated set of numbers zkl which correspond to the known field values, with 1 ≤ k ≤ m, 1 ≤ l ≤ n, we have to find a bivariate function z=f(x, y) that interpolates the data (field solution), i.e., z = f(xk, yl) = zkl for all values of k and l . The grid points must be sorted monotonically, i.e. x1 < x2 <...< xm with a similar ordering of the y-ordinates.

To generate a bivariate interpolant on the rectangular grids and calculate the value in the points specified in the arrays ix and iy it is used a spline interpolation. For example along lines in the x direction,

dcxbxax)x(P +++=23 (1)

The corresponding mathematical spline must have a continuous second derivative

and satisfy the same interpolation constraints. The breakpoints of a spline are also referred to as knots.

The first derivative P/(x) of our piecewise cubic function is defined by different formulas on either side of a knot xk. Both formulas yield the same value kd at the knots, so P/(x) is continuous.

2. Case Studies

It is presented as illustration examples two case studies regarding the magnetic field emanated from Very High Voltage Power Lines. Case 1 corresponds to a single Line and Case 2 corresponds to two Lines orthogonally placed to each other. For both cases the electrical conditions are the same, with 220kV and 1140A per phase conductor. Both Lines have 100m length. The solution plane is defined by a span of Line and it was considered as reference, a grid defined by one meter space between nodes in the solution plane. This discretization corresponds to a grid with 10000 nodes and produces a smoother solution of the magnetic field. It is seen in Fig. 1 the magnetic field distribution (smoother solution) in the solution plane for Case 1, and in Fig. 2 for Case 2.

Figure 1. Magnetic Field smoother solution (Case 1)

C. Lemos Antunes et al. / Reducing Computational Time 169

Figure 2. Magnetic Field smoother solution (Case 2)

To obtain the magnetic field for Case 1 and Case 2, with 10000 nodes a

considerable computational time was required namely 1245 sec and 2421.9 sec respectively.

The idea was then to produce a magnetic field solution as accurate as possible but with considerable much less computational time.

3. Results

Three different grids with two meter space, five meter space and ten meter space between nodes were used. The field solutions at these nodes were exactly the same as for the finer grid and the derived field solution for the other nodes of the finer grid were processed by the interpolation function.

It is shown in Fig. 3 the different computational time t versus the number of nodes n for Case 1.

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 100000

200

400

600

800

1000

1200

1400

n=nº of nodes

t=C

ompu

tatio

nal t

ime

[s]

Figure 3. Computational time (Case 1)

C. Lemos Antunes et al. / Reducing Computational Time170

The function ( )t t n= can be approximated by Eq. (2). ( ) 6212420 ,n,nt +⋅= (2)

To access the accuracy of the field solution, a nodal local error parameter εn [%]

was calculated, as:

[ ]ref

refnn B

BB −

=%ε (3)

Where Bn is the magnetic field value obtained at the nodes for the coarser grid and

refB is the corresponding magnetic field value obtained with the reference grid (one meter space between nodes).

In Fig. 4 it is shown in the form of coloured plot the visualization of a 2D projection of the error distribution at the nodes in the plane of analysis for one grid defined by 10 meter space between nodes for Case 1.

0

8.33e-003

1.67e-002

2.50e-002

3.33e-002

4.16e-002

5.00e-002

0 10 20 30 40 50 60 70 80 90 1000

10

20

30

40

50

60

70

80

90

100Error (%) - 10x10 grid

x

y

Figure 4. 2D projection of the error distribution in plane (Case 1)

In the form of graphic it is shown in Fig. 5 the variation of εn [%] for a line

y = 70 m for the three different grid discretization and in Fig. 6 it is shown the variation of εn [%]for a line x = 70 m.


Figure 5. 2D error distribution in plane for x direction (Case 1)

Figure 6. 2D error distribution in plane for y direction (Case 1)

As it is seen the error εn [%] varies in the range of [0; 0,05] %, and the

computational time to get the magnetic field solution is 15sec, thus 83 times lower than the time to obtain the field solution for 10000 nodes.

For Case 2, it is shown in Fig. 7 the computational time t versus the number of nodes n corresponding to these different grids.

X10-2

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

x

Erro

r [%

]

Error in y direction to x=70

2x25x510x10

X10-2

0 20 40 60 80 100 1200

0.5

1

1.5

2

2.5

3

3.5

4

4.5

x

Erro

r [%

]

Error in x direction to y=70

2x25x510x10


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 100000

500

1000

1500

2000

2500

n=nº of nodes

t=C

ompu

tatio

nal t

ime

[s]

Figure 7. Computational time (Case 2)

The function t = t(n) can be approximated by equation 4. ( ) 6,22416,0 +⋅= nnt (4)

In Fig. 8 it is shown the visualization of a 2D projection of the error distribution in

plane of analysis for one grid defined by 10 meter space between nodes for Case 2.

0

2.34e-002

4.67e-002

7.01e-002

9.34e-002

1.17e-001

1.40e-001

0 10 20 30 40 50 60 70 80 90 1000

10

20

30

40

50

60

70

80

90

100Error (%) - 10x10 grid

x

y

Figure 8. 2D projection of the error distribution in plane (Case 2)

In this case the error εn [%]varies in the range of [0; 0,14] %. It is shown in Fig. 9 the variation of εn [%] for a line y = 70 m for the three

different grid discretization and in Fig. 10 it is shown the variation of εn [%]for a line x = 70 m.


Figure 9. 2D error distribution in plane for x direction (Case 2)

Figure 10. 2D error distribution in plane for y direction (Case 2)

The nodal error for Case 2 is bigger than for Case 1, but still very low and quite

acceptable. The computational time to get the magnetic field solution is 30sec, thus 80 times lower than the time to obtain the field solution for 10000 nodes.

4. Conclusions

It was presented an algorithm to reduce the computational time in obtaining the magnetic field distribution in a plane of analysis due to Very High Voltage Power Lines. The nodal error in the field solution is quite negligible when comparing solution obtained with finer grids in plane of analysis.

This algorithm is implemented in the LMAT_SIMAG software, which is part of a more complete package LMAT_SIMX that allows the analysis and simulation of

0 20 40 60 80 100 1200

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

x

Erro

r [%

]

Error in y direction to x=70

2x25x510x10

X10-2

X10-2

0 20 40 60 80 100 1200

2

4

6

8

10

12

x

Erro

r [%

]

Error in x direction to y=70

2x25x510x10


Electrical and Magnetic Fields emanated from very High Voltage Power Lines, developed by the authors.

Acknowledgments

The authors gratefully acknowledge REN-Redes Energéticas Nacionais SGPS, SA for the financial support received under Project COIMBRA_EMF.ELF.

References

[1] Carlos Lemos Antunes, José Cecílio, Hugo Valente, “LMAT_SIMAG – The Magnetic Field numerical calculator of the package LMAT_SIMX for Very High Voltage Power Lines”, Proceedings and CD-Rom of Conference EHE 07 – 2nd International Conference on Electromagnetic Fields, Health and Environment, Wroclaw (Poland), 10-12th Sept, 2007.

[2] www.mathworks.com/access/helpdesk/help/techdoc/ref/index.html. [3] www.mathworks.com.


LMAT_SIMAG – The Magnetic Field

Numerical Calculator of the Package

LMAT_SIMX for Very High Voltage

Power Lines

Carlos LEMOS ANTUNES a, b, d, 1

, José CECÍLIO b

, Hugo VALENTE c

a

Electrical Engineering Dept,University of Coimbra, Coimbra, Portugal

b

APDEE – Assoc. Port. Prom. Desenv. Eng. Electrotécnica, Coimbra, Portugal

c

REN – Rede Eléctrica Nacional, Lisboa, Portugal

d

CASE – Centro de Accionamentos e Sistemas Eléctricos

Abstract. In this paper it is presented the software tool LMAT_SIMAG, the 3D

Magnetic Field numerical calculator of the package LMAT_SIMX that allows the

calculation and simulation of ELF electric and magnetic fields emanated from

Very High Voltage Power Lines (HVPLs). The formulation is based on the Biot-

Savart law, with the catenary of the Line(s) approached by straight lineal segments,

where each segment makes a contribution to the magnetic field at point of analysis.

Each segment is considered as a filamentary wire. The Lines under analysis can

have different configurations and orientations and the field solution can be

expressed in terms of the resultant components in the x, y, z directions due to each

separate Line or all the Lines. This software was developed in MATLAB

environment is very easy to use and has a user friendly interface.

Keywords. LMAT_SIMAG, LMAT_SIMX, High Voltage Power Lines (HVPLS)

Introduction

The LMAT_SIMAG is the software tool developed in MATLAB [1-2] environment,

used for the calculation and simulation of ELF magnetic fields emanated from Very

High Voltage Power Lines. In this software tool, the electric and geometric data about

the Line(s) is loaded from the database generated by the module

LMAT_GEOMODELA[3]. This module also allows the user to choose the points or

the plane where the magnetic field is to be calculated. The formulation of the magnetic

field numerical calculator is based on the Biot-Savart law. The LMAT_SIMAG

calculates the magnetic field resulting from general 3D Line(s) configurations of

current-carrying conductors.

_________________________

1

Corresponding Author: Lab. CAD/CAE, Electrical Engineering Dept, University of Coimbra, Pólo II,

3030 – 290 Coimbra, Portugal; e-mail: [email protected].



176

The conductors are considered filamentary wires of arbitrary path and the catenary is

approximated by straight lineal segments. The magnetic field can be calculated along

any path or on any plane. The modules referred to in this paper are part of the package

LMAT_SIMX that allows the calculation and simulation of ELF electric and magnetic

fields emanated from HVPLs.

This software tool is very easy to use and has a user friendly interface.

1. Formulation

Each Line is subdivided in lineal segments, where each segment is defined by a

function ( ) ( ) ( )( ), ,f x t y t z t , that is approached by a third degree polynomial (1).

( )

( )

( )

2 3

0 1 2 3

2 3

0 1 2 3

2 3

0 1 2 3

x t a a t a t a t

y t b b t b t b t

z t c c t c t c t

= + ⋅ + ⋅ + ⋅

= + ⋅ + ⋅ + ⋅

= + ⋅ + ⋅ + ⋅

(1)

Where t is a parameter that describes the position along the segment length.

Normalizing each segment (i.e., considering each segment with a unitary length),

with 4 interpolating nodes it is possible to obtain the coefficients of the Eq. (1) as

follows:

( )

( )

( )

( )

0 1

0 1 2 3 2

0 1 2 3 3

0 1 2 3 4

0

1 1 11

33 9 27

2 4 82

33 9 27

1

x a x

x a a a a x

x a a a a x

x a a a a x

= =

= + ⋅ + ⋅ + ⋅ =

= + ⋅ + ⋅ + ⋅ =

= + + + =

(2)

or using matrix notation:

0 1

1 2

2 3

3 4

1 0 0 0

1 1 3 1 9 1 27

1 2 3 4 9 8 27

1 1 1 1

a x

a x

a x

a x

⎡ ⎤ ⎡ ⎤⎡ ⎤

⎢ ⎥ ⎢ ⎥⎢ ⎥

⎢ ⎥ ⎢ ⎥⎢ ⎥⋅ =

⎢ ⎥ ⎢ ⎥⎢ ⎥

⎢ ⎥ ⎢ ⎥⎢ ⎥

⎣ ⎦ ⎣ ⎦⎣ ⎦

(3)

The terms ( )y t and ( )z t are obtained in a similar way.

From Eq. (1) it is obtained by differentiation:

C. Lemos Antunes et al. / LMAT_SIMAG – The Magnetic Field Numerical Calculator 177

( )

( )

( )

2

1 2 3

2

1 2 3

2

1 2 3

2 3

2 3

2 3

dx a a t a t dt

dy b b t b t dt

dz c c t c t dt

= + ⋅ ⋅ + ⋅ ⋅ ⋅

= + ⋅ ⋅ + ⋅ ⋅ ⋅

= + ⋅ ⋅ + ⋅ ⋅ ⋅

(4)

Throughout the analysis sinusoidal time varying quantities will be assumed.

The magnetic field produced by each segment carrying an electrical phasor current

ˆ

j

I I e

θ⋅

= ⋅ is given by

4 4

0 0

2 31 1

ˆ

4 4

Idl R dl R

B I

R R

μ μ

π π

⋅× ×

= ⋅ ⋅ = ⋅∫ ∫

(5)

Where

( ) ( ) ( )ˆ ˆ ˆ

x y z

R x x a y y a z z a′ ′ ′= − ⋅ + − ⋅ + − ⋅

(6)

and

ˆ ˆ ˆ

x y z

dl dx a dy a dz a= ⋅ + ⋅ + ⋅

(7)

ˆ

x

a , ˆy

a , ˆz

a are the unit vectors along the direction x, y, z respectively.

For each segment of a Line, say i, the components Bxi, By

i and Bz

i of the magnetic

field at a given point are then calculated, and the procedure repeated for all the

segments of that Line and for all the other Lines.

The value of the resultant components BxR, By

R and Bz

R will be the arithmetic

sum of the contributions due to each segment.

The magnetic field is a vector where the components in the x, y, z directions are

also phasors, thus varying in time in a sinusoidal way. For magnetic field exposure

analysis we are mainly interested in the effective value of the magnetic flux density

ef

B , and not the instantaneous values.

In this case we define ef

B as:

( ) ( ) ( )Re Im Re Im Re Im

2 2 2 2 2 2

*ˆ ˆ

2 2

al ag al ag al ag

x x y y z z

ef

B B B B B BB B

B

+ + + + +

⋅

= =

(8)

Where ˆ

B is the magnetic field value, which is also a complex value, and *

ˆ

B is the

complex conjugate of ˆ

B .

The magnetic field value has three components ˆ

x

B , ˆ

y

B and ˆ

z

B , where each

component is also a complex number, i.e., for example, Real Imag

ˆ

x x x

B B jB= + .

C. Lemos Antunes et al. / LMAT_SIMAG – The Magnetic Field Numerical Calculator178

2. User Interface

When LMAT_SIMAG is initialized the window (Fig. 1) appears on the screen. In this

window it is shown the geometric configuration of the Line(s) (a)

. At first, the user

selects one Line (b)

and introduces the corresponding electric state, i.e., the rms Line

Voltage and Electrical Current in amplitude and phase (c)

. After the introduction of this

information for all the Lines, the user selects the points where the magnetic field is to

be calculated (d)

. It is possible the choice between two different formats, i.e., either the

user introduces the points in a discrete way (one by one), or introduces three points to

define the plane (e)

and decides the grid of points in that plane, by indicating the range

in the x and y direction (f)

and the increment (g)

.

(c ).

(b)

(a)

(d)

(e)

(f)

(g)

(h) (i)

(j)

Figure 1. Interface

If the user opts for first type, the following windows (Fig. 2 and Fig. 3) appear on

the screen, indicating the total number of input Points and coordinates for each point

entered.

Figure 2. Indication of the total number of Points

Figure 3. Inserting coordinates for each Point


When the user completes the information about all Lines and points and clicks on

“pre-view configuration” (h)

it appears in window (a)

the geometric configuration of the

Line(s) and the points where the magnetic field is to be calculated.

When the user completes all the input information it is necessary to click on

“solve” (i)

to start the calculation process. This calculation process may take

considerable computation time depending on the level of refinement of the grid. After

the calculation is completed, a sketch of magnetic field distribution is shown (j)

.

In this interface some other menus also exist that allow the saving of the current

configurations, the load of a configuration from file and the call of the module

LMAT_VISUAL.ELF for manipulation and visualization of the field distribution.

3. Results

It is presented as an illustration example the magnetic field emanated from two High

Voltage Power Lines (232 kV) carrying 235.6 A per phase conductor in one Line and

103.4 A in other Line, which corresponds to 20,7% of full capacity for Line 1 and 9,1%

for Line 2.

The first Line has 262.4m of length and the catenary parameters for each

conductor cable and guard cable are 1602 and 2300 respectively. The second Line has

238.8m of length and the catenary parameters are 1254 for each conductor cable and

2720 for guard cable. To generate the geometric configuration of the Lines it is used

the module LMAT_GEOMODEL [1]. In this example the solution plane is defined by

a span of the Lines and has a slope defined by coordinates of the supports. The solution

plane was 1.8m above the ground level.

To get a deeper analysis of the results it is necessary to use the

LMAT_VISUAL.ELF module [4]. This module is part of the package LMAT_SIMX

and allows the visualization and manipulation of ELF Magnetic/Electric fields.

In Fig. 4 it is shown the 3D distribution of the magnetic field at 1.8m above the

ground level graded by a scale colours pre-defined by the user.

Figure 4. Distribution of magnetic field on the plane with attributed scale colours


In this example the maximum and minimum magnetic field flux density values are

2,96μT and 0,18μT. The maximum magnetic field value is found at circa 43% of length

below of the Line.

To obtain a 2D distribution, i.e., view a 2D section of the 3D solution profile, it is

necessary to specify the plane (x or y), as well the field components to be represented.

In Figure 5 it is presented a cross section 2D distribution and the components of

the resultant flux density for x equal to the location corresponding to the maximum

value.

Figure 5. 2D Field distribution in a plane

In Fig. 6, and 7 it is shown the components of the resultant flux density and the

contribution of each Line.

Figure 6. Components of flux density due to Line 1


Figure 7. Components of flux density due to Line 2

The LMAT_VISUAL.ELF offers three different forms of visualization of the 2D

projection of the field distribution. Type 1 corresponds to a field representation of

coloured shaded plots with contour lines that correspond to isovalues of the field. In

Type 2, the field is represented by coloured points on nodes. The colour is pre-defined

by the user and represents a range of the field. Type 3 corresponds to a representation

with circles where the radius is proportional to the field amplitude. The maximum

radius used in the representation corresponds to half space between nodes in regular

grids. These types of graphics can be applied to a single Line or the full set.

In Fig. 8, 9 and 10 it is shown the visualization of a 2D projection of the field

distribution, represented by these three different forms.

Figure 8. 2D Projection of the field represented by type 1




4. Accuracy Tests

To certify the magnetic field numeric results, the magnetic field was measured on a set

of points regularly distributed on the 5x10m plane at ground level close to the Lines.

A grid of points was created in that plane. The points in this grid are 2,5 m spaced in

the bigger dimension and 1,75 m spaced in the smaller dimension (Fig. 12 and 13).


Figure 11. Set of the points

Figure 12. Location of the points

Figure 13. Numeration of the points

The measurement equipment used was the Programmable Dosimeter EMDEX II –

High Field, from ENERTECH (USA) (Fig. 14).

This device allows the register of field variations versus time for any point, for

latter graphics and statistic analysis of the measured values.

This equipment measures the effective value (rms) of the magnetic field in the

three componentsˆ

x

B , ˆ

y

B and ˆ

z

B . The value of the resultant magnetic field is obtained

by Eq. (9).

2 2 2

(R X Y Z

B B B B= + + (9)


Figure 14. EMDEX II - The measurement equipment

It is presented in Table 1, the comparison between the experimental measured

values and the corresponding numerical values for the magnetic field at the grid points.

The absolute error ε is defined by Eq. (10).

Numerical Measured

B Bε = − (10)

Table 1. Numerical and Measured values

Point

Bef (Numerical)

[µT]

Bef (Measured)

[µT]

ε [µT]

1 1,0052 0,925 0,0802

2 1,1062 0,925 0,1812

3 1,1954 1,025 0,1704

4 1,2643 1,025 0,2393

5 1,3058 1,175 0,1308

6 1,2889 1,225 0,0639

7 1,2493 1,025 0,2243

8 1,1828 1,025 0,1578

9 1,0959 0,825 0,2709

10 0,9973 0,875 0,1223

11 0,9892 0,875 0,1142

12 1,0855 0,925 0,1605

13 1,17 1,025 0,145

14 1,2345 1,025 0,2095

15 1,2721 0,725 0,5471


In Fig. 15 it is presented in graphic form the numerical and measured values of the

Magnetic Field for the grid points in the solution plane.

2 4 6 8 10 12 140

1

2

3

4

5

6

7

8

9

10

B [

uT]

Point n.º

Evolution of the B

Numerical Bef

Measured Bef

Figure 15. Numerical and Measured values for the Magnetic Field

Some conclusions can be extracted:

• The magnetic field does not vary significantly in the points of the solution plane. The

values of magnetic induction B, are globally between 0,825 µT and 1,225 µT. The

maximum field value is 1,225 µT, corresponding to point 6 and the errors vary in the

range of [0,0639; 0,2709] µT.

• These values correspond to the values of the resultant (rms) considering the

fundamental component and harmonics. The fundamental component is practically

coincident with the resultant, i.e., the contribution of the harmonics is negligible.

• The error in the field solution is seen to be quite negligible when comparing the

numerical values with the measured ones.

5. Conclusions

It was presented the major useful facilities implemented in this powerful design tool.

This software is part of a more complete package LMAT_SIMX that allows the

analysis and simulation of Electrical and Magnetic Fields emanated from very High

Voltage Power Lines, developed by the authors.

Acknowledgments

The authors gratefully acknowledge REN-Redes Energéticas Nacionais SGPS, SA for

the financial support received under Project COIMBRA_EMF.ELF and Mr Tony

Almeida for some useful discussions regarding part of this work.


References

[1] www.mathworks.com

[2] Mathworks, “Creating Graphical User Interfaces”, September 2006, Revised for MATLAB 7.3

[3] Carlos Lemos Antunes, José Cecílio, Hugo Valente, “LMAT_GEOMODEL – The geometric

configuration modeller of the package LMAT_SIMX for Very High Voltage Power Lines”, 10th

Portuguese-Spanish Conference in Electrical Engineering – XCLEEE, pp. 4.67-4.70, Funchal

(Portugal), 5-7 July, 2007.

[4] Carlos Lemos Antunes, José Cecílio, Hugo Valente, “LMAT_VISUAL.ELF – Software tool for

visualization and manipulation of ELF Magnetic/Electric fields emanated from Very High Voltage

Power Lines”, 10th Portuguese-Spanish Conference in Electrical Engineering – XCLEEE, pp. 4.21-4.24,

Funchal (Portugal), 5-7 July, 2007.


Montecarlo Evaluation of Long Term

Exposure to ELF Magnetic Fields from

Independent Power Lines

Giovanni LUCCA

SIRTI S.p.A.,Via Stamira d'Ancona 9, 20127 Milano Italy;

E-mail:[email protected]

Abstract – This paper is focused on the evaluation of the environmental magnetic

field produced by independent power lines in order to assess long term exposure

for human beings. The proposed and novel approach, based on the Montecarlo

method, directly takes into account of the intrinsic random nature of the problem.

Keywords. Power lines, magnetic field, random variables.

1. Introduction

In many countries a spread public concern exists about possible (but not demonstrated

till now) long term adverse effects for the human health produced by Extremely Low

Frequency (ELF) magnetic fields (typically 50-60Hz). Just for information, we add that

the limits introduced by some countries (e.g. Italy, Israel, Switzerland or in some states

of USA) in order to protect population against the supposed adverse effect of long

term exposure are very low; they are infact one or two orders of magnitude lower than

the ones established for short term effects (e.g. in the European Union a limit of 100μT

exists for short term effects). For such a reason, in many cases involving power and

industrial installations, there is the need to evaluate the magnetic field produced by

them in order to verify if its value is lower than the one prescribed by the relevant

national standards and regulations in force.

Often, the evaluation consists in calculations that are generally preferred to

measurements because they allow a significant save of time and money and, at the

same time, they permit to give a more complete description of the field in the space

region of interest; moreover, calculation is the only tool at disposal in case of new

plants when they are still at the design or construction stage.

The main problem we want to treat in this paper is the superposition of the effects

produced by two or more independent sources generating a magnetic field in the same

space region. In principle, we have to add the fields produced by each single plant;

nevertheless, even if we know with good precision the input data relevant to each

single installation (i.e. geometrical and physical characteristics and currents circulating

in the conductors), when we vectorially add the single contributions (each one



188

represented by a vector phasor), we also need to know phase shift angles among them

in order to make a correct summation. Such phase shift angles (among the fields) are

the phase shift angles among the current terns relevant to each single plant.

In order to better explain the meaning of the phase shift angle see Fig.1 for a

simple example applied to three symmetrical terns.

Such an aspect seems not to be adequately considered in technical literature; as far

as we know, only some papers (focused on fields generated by two independent power

lines) put it into evidence [1]-[3]: in particular, they show that significant differences

can exist between different calculations done by assuming different values for the

phase shift ϕ.

Thus, in general, with N independent plants and by considering the phase angle of

one of them as reference, we have N-1 phase shifts ϕi (i=1,2,..N-1) that must be known

in order to make calculations.

It is also necessary to remark that, depending on load conditions, both phase shifts

among different plants and currents circulating in each single power line are not

constant but vary with time on a scale that can be daily, weekly and seasonal. Such

variations are affected by random factors that lead to a probabilistic and statistical

approach of the magnetic field evaluation, especially if it is aimed to estimate the long

term exposure.

Thus, on the basis of these considerations, it appears that a Montecarlo approach

can be fruitful and has the advantage of automatically reflecting the intrinsic random

nature of the problem.

Figure 1. Example of phase shift angles among three different terns where one of them has been taken

as reference.

ϕ1

ϕ2

G. Lucca / Montecarlo Evaluation of Long Term Exposure to ELF Magnetic Fields 189

2. Description of the Calculation Method

2.1. Outline of the Basic Formulas

The basic formula for calculating the magnetic flux density field B, in free space, in a

generic point of coordinates (x, y, z) produced by a thin wire, is given by [4]:

( ) ∫Γ

×

π

μ

=2

r0

r

usdI

4rB

(1)

being I a complex phasor representing the current flowing in the wire Γ, μ0 the absolute

magnetic permeability of vacuum while the other quantities are represented in Fig.2

Figure 2. Geometrical elements involved in formula (1).

Thus, provided that the sources of the magnetic field can be modeled by wires, the

application of formula (1) allows to describe any plant even with complex geometrical

configurations (i.e. non parallelisms, crossings, down conductors). Moreover, if the

curve Γ is discretised and approximated by means of a suitable number of straight

segments an analytical formulation for the field B can be deduced from formula (1).

Let us suppose we have to calculate the magnetic flux density field produced by N

independent power lines circuits each one characterized by a balanced current Ii

(i=1,2,..N) and by phase shifts ϕk (k=1,2,..N-1): by applying formula (1), the modulus

of the field B in a generic space point (x, y, z) is expressed, in a formal way, by a

relation of the type:

( )1N21N21

,..,,I,..I,I,z,y,xBB−

ϕϕϕ=

(2)

Γ

ds

r

(x,y,z)

ur

I

G. Lucca / Montecarlo Evaluation of Long Term Exposure to ELF Magnetic Fields190

2.2. Random Quantities

As already remarked, the currents Ii in the power circuits and the phase shifts ϕ

k are

random variables because they depend on the continuous and random variation of the

load conditions relevant to the considered power circuits. The statistical distributions of

such quantities can be derived from the database relevant to recordings, over long time

periods, of real and reactive powers as well as voltages measured at the receiving or

sending ends of the involved lines; this kind of database should be available at the

power line operator.

In the event of this historical database would not be available or existing (e.g. in

case of lines under construction) one could adopt, on the basis of previous knowledge

and experience, a certain ''a priori'' distribution (e.g. the uniform or normal

distribution).

Anyway, in order to be able to perform a Montecarlo simulation, one must know

the N probability density distributions of the currents Ii circulating in the N power

circuits and the N-1 probability density distributions of the phase shifts among the

power circuits.

Thus, by looking at formula (2), the magnetic flux density field can be considered

as a random variable function of 2N-1 independent random variables.

2.3. Output of the Montecarlo Method

The Montecarlo method (also said of statistical trials) [5] consists, in this case, in

assigning, to each of the 2N-1 independent variables, a random value according to their

respective probability distributions and then in calculating the magnetic flux density

field according to formula (2); thus, after a suitable number M of trials, one can obtain

a statistical distribution of the field B for each point (x, y, z) in the space .

Finally, by processing the data relevant to such a distribution, it is possible to

deduce a certain number of statistical quantities that are of main interest for assessing

long term exposure. The most meaningful are the mean and median values.

In particular, for the mean value it is possible to give an estimation of the error.

Infact, if:

• Bm(x, y, z) is the mean value (in modulus) of the field;

• bi(x, y, z) is the field value (in modulus) resulting from the i-th trial;

• σ is the standard deviation of the random variable B(x,y,z).

we have that the error e(x,y,z) is expressed by:

( ) ( ) ( )z,y,xBz,y,xb

M

1

z,y,xem

M

1i

i

−= ∑=

(3)

The summation in formula (3) is the sample mean of M-th order that we indicate by:

( ) ( )∑=

=

M

1i

iM

z,y,xb

M

1

z,y,xB (4)


As a direct consequence of the Central Limit Theorem and of the so called ''three

sigma rule'', it is possible to estimate the following probability P [5]:

( )( )

997.0

M

z,y,x3

z,y,xeP ≈

⎭

⎬

⎫

⎩

⎨

⎧ σ

< (5)

We can notice that the error is inversely proportional to the square root of the

number M of trials.

Actually, we do not know the standard deviation σ, but usual practice is to replace

it, in formula (5), by the sample standard deviation sM

(x,y,z) of M-th order evaluated

through the formula:

( ) ( ) ( )( )∑=

−=

M

1i

2

MiMz,y,xBz,y,xb

M

1

z,y,xs (6)

We would like to remark that the statistical quantities in formulas from (3) to (6)

are all function of the space point (x, y, z); that means we have to run M trials for each

space point to be considered.

3. Examples of Application

3.1. Introduction

This paragraph presents two examples of application relevant to two real cases that are

based on simple geometries (parallel and infinite conductors) and on the minimum

number of independent plants i.e. two; these are not limitations of the method that, in

principle, can be applied to cases with any number N of independent plants and with

more complex geometries and line layouts even if with more computational effort.

3.2. Two Independent Power Lines: Constant Currents

The first example deals with a double circuit 132 kV, 50 Hz power line that is still at

the design stage and is devoted to supply two independent electrified railway lines (the

first one 3 kV d.c. and the other one 25 kV, 50 Hz); the six conductors forming the

double circuit are installed on the same masts for a considerable length.

Even if the lines are not still existing, it is necessary to make a previsional

evaluation of the magnetic field produced by the currents circulating in the two circuits.

In this example the currents are assumed to be known and constant but the phase

shift ϕ is assumed to be a random quantity uniformly distributed in the interval [00

,

3600

]; thus, in this case, the problem is characterized by only one random variable.

The conductors are treated, for simplicity, as infinite straigth wires having constant

mean height with respect to the soil (i.e. the catenary effect is neglected); such a

simplied geometry allows for the use of a bidimensional model described by the well

known Biot-Savart formula [6].

In Table 1 the conductors position and the current circulating on them are reported.


Table 1: Conductors position and current

Abscissa [m] Ordinate [m]

Current: real

part [A]

Current:

imaginary part

[A]

2.8 28 0 0

3.8 24 0 -106

3.1 20 0 106

-2.8 28 -165 -85

-3.8 24 -46 141

-3.1 20 211 -56

The plots of Figure 3a represent the mean and median values (rms) of the magnetic

flux density field versus lateral distance x from the line axis. Each curve is relevant to a

fixed height h from the soil. These results have been obtained by means of 4000 trials.

Figure 3a. Mean (solid lines) and median (dashed lines) values of the magnetic flux density field versus

lateral distance evaluated at different heights h from the soil; M=4000.

80 60 40 20 0 20 40 60 80

0

1

2

3

4

5

6

lateral distance [m]

h=5m

h=15m

h=10m

h=1m

mean

an

d m

ed

ian

v

alu

e of B

[μ

T]


Figure 3b. Upper bound of the error (referred to the mean value) versus lateral distance evaluated at different

heights h from the soil; M=4000.

It is interesting to note that, in all the cases, the curves of mean and median values

are practically overlapping.

On the basis of formula (5), the upper bound of the error e(x,y,z) versus the lateral

distance from the line axis has been plotted in Figure 3b.

3.3. Two Independent Power Lines: non Constant Currents

The second example deals with a double circuit 380 kV, 50 Hz, with balanced currents,

that is in operation; the six conductors forming the double circuit are installed on the

same masts for a considerable length.

In this case we have at disposal some historical data concerning the currents

flowing in the two circuits as well as the the phase shift between them; in particular, the

currents circulating in the first and second circuits have values inside the intervals

[10A, 410A], [320A, 720A] respectively, while the phase shift ranges inside the

interval [00

, 3600

].

Therefore, in this case, we have three random variables that are:

• the current I1 in the first circuit;

• the current I2 in the second circuit;

• the phase shift ϕ between the two circuits.

80 60 40 20 0 20 40 60 80

0

0.01

0.02

0.03

0.04


h=15m

h=10m

h=1m

h=5m

up

per b

oun

d o

f th

e erro

r [μ

T]


We further assume that:

• the current I1 has normal distibution with mean value equal to 210A and standard

deviation equal to 57.14A: that means a probability of 0.046% of having a value

for I1 outside of the interval [10A, 410A];

• the current I2 has normal distibution with mean value equal to 520A and standard

deviation equal to 57.14A: that means a probability of 0.046% of having a value

for I2 outside of the interval [320A, 720A];

• the phase shift ϕ between the two circuits is uniformly distributed inside the

interval [00

, 3600

]1

.

We remark that the assumption of normal distribution for the currents is fairly

reasonable as confirmed also by measurements. See for example [7].

As far as geometry is concerned, also in this case we model the conductors by

means of infinite straight wires having constant height with respect to the soil.

In Table 2, the conductors position and information about the current are reported.

Table 2. Conductors position and current

Abscissa [m] Ordinate [m] Current Phase current

-9.43 47 I2

00

-9.93 38 I2 240

0

-10.63 29 I2 120

0

9.43 47 I1 120

0

9.93 38 I1 240

0

10.63 29 I1 0

0

The plots of Figure 4a represent the mean and median values (rms) of the magnetic

flux density field versus lateral distance from the line axis are. These results have been

obtained by means of 4000 trials. In Figure 4b, the upper bound of the error e(x,y,z)

versus lateral distance from the line axis has been plotted.

1

In other cases, this assumption is not realistic because the range of the phase shift is restricted to a much

narrower interval.


Figure 4a. Mean (solid lines) and median (dashed lines) values of the magnetic flux density field versus

lateral distance evaluated at different heights h from the soil; M=4000.

Figure 4b. Upper bound of the error (referred to the mean value) versus lateral distance evaluated at different

heights h from the soil; M=4000.

100 80 60 40 20 0 20 40 60 80 100

0

0.005

0.01

0.015

0.02

0.025


up

per b

oun

d o

f th

e erro

r [μ

T]

h=15m

h=10m

h=5m

h=1m

100 80 60 40 20 0 20 40 60 80 100

0

0.5

1

1.5

2

2.5

3

3.5

4

mean

an

d m

edian

v

alu

e of B

[μ

T]


h=15m

h=10m

h=5m

h=1m


4. Conclusions

We have presented in this paper a novel method to assess the ELF magnetic flux

density field produced by independent power lines; the calculation procedure, based on

the Montecarlo method, takes into account, in a natural way, of the intrinsic random

nature of the problem allowing to easily get some statistical quantities, like mean and

median values, of the field (in each point of the space) that are of main importance in

estimating the long term human exposure.

References

[1] G. Mazzanti, The Role Played by Current Phase Shift on Magnetic Field Established by AC Double-

Circuit Overhead Transmission Lines-Part I: Static Analysis'', IEEE Trans. On Power Delivery, vol.21,

pp. 938-948, Apr. 2006.

[2] M. Albano, R. Benato, R. Turri, Predictive Analysis of Environmental Magnetic Fields Generated by

Multiple Power Lines, Proc. IEEE Power Tech Conference, June 23-26 2003, Bologna, Italy.

[3] M. Albano, R. Benato, R. Turri, 'Determination of Line Current Phase Angle Displacement from

Magnetic Field Measurements in Multiple-Corridor Power lines', Proc. UPEC Conference, September

1-3 2003, Thessaloniki, Greece.

[4] C. T. A. Johnk, Engineering Electromagnetic Fields and Waves, 1st ed., John Wiley &Sons, 1975.

[5] M. Sobol, The Monte Carlo Method, 2nd ed., MIR Publishers Moscow, 1984.

[6] IEEE Magnetic Fields Task Force, ''Magnetic Fields from Electric Power Lines Theory and

Comparison to Measurements, IEEE Trans. On Power Delivery, vol. 3, pp. 2127-2136, Oct. 1988.

[7] J. Hoeffelman, G. Decat, J-L. Lilien, A. Delaigle, B. Govaerts, Assessment of the electric and magnetic

field levels in the vicinity of the HV overhead power lines in Belgium', paper C3-202, CIGRE Session

2004, Paris.


Medical Image Segmentation Hybrid Algorithm Based on Otsu Method and

Markov Random Fields 1R. LUDWICZUK, 2P. MIKOLAJCZAK

1Agricultural University in Lublin, Akademicka 13, Lublin, Poland [email protected]

2Maria Curie Sklodowska University, Pl. M Curie Sklodowskiej 1, Lublin, Poland [email protected]

Abstract. The aim of this paper is to present a hybrid method of image segmentation based on Otsu algorithm and Markov Random Fields simulations. This method has been employed for biomedical images coming from Magnetic Resonance Imaging (MRI). As a result we have received a segmented image of the human head.

Introduction

One of the problems in current neurosurgery is to minimize the effects of brain damages. During the neurosurgery operation patient can lose some functions of the brain. If we know the map of brain functions around the pathology, we could choose an optimal way of operation. What is more, preparing patient to such operation is too long and painful (patient must be conscious in the first part of operation). Generally speaking it is necessary to create this map.

We can create the map of brain functions by making use of functional magnetic resonance imaging (fMRI) [4]. Connection between the brain activity and intensity of blood flow is the base of fMRI. Furthermore, it is known the Linus Pauling condition invented in 1935. It shows that magnetic features of blood depends on its oxygen contents. It occurs, that oxyhemoglobin has the diamagnetic property and deoxyhemoglobin has the paramagnetic property. So, hemoglobin is a natural contrast substance causing local changes in homogeneous magnetic fields. Increase of field activity isn’t high (for scanners 1,5T equal 2-5%). It is enough for taking images of active parts of the brain.

fMRI in contrast to MRI has a low quality (i.e. low resolution). We can map information from fMRI to classical MRI (MRI with more details). For mapping we must take an active part from fMRI, localize and connect it with accurate regions in MRI. Segmentation is an instrument for this process.

To create this instrument we need mathematical description of image. In the real scene, pixel intensity depends on its neighborhood. The Markov Random Fields are the best for showing this property. In statistical terms (w szczególności MRF), segmentation problem can be defined as:



198

• supervised segmentation – number of regions and the model parameters are known a priori;

• semi-unsupervised segmentation – model parameters may be unknown; • unsupervised segmentation – number of regions and model parameters may be

unknown. The most desirable is a solution of unsupervised segmentation problem, a fully

automatic segmentation.

Theory

This article presents the solution of semi-unsupervised segmentation due to a connection of two statistical segmentation method in to a hybrid algorithm. The first method, as preliminary segmentation, is Otsu algorithm. The parameters obtained at this stage create input parameters vector for the second part of the algorithm, MRF simulation, which is a proper segmentation.

Otsu Method

The process of preliminary segmentation is a statistical method for image thresholding based on Otsu algorithm. As a result of this process we obtain optimal vector of thresholds.

Assuming that: • image is 2D intensity function; • image contains n pixels with intensity levels from 0 to L-1, where L is a

number of intensity levels; • histogram of image can be treated as probability density,

we can denote:

nn

p ii =

(1)

∑−

=

=

1

01

L

iip

(2)

where:

ip - probability for pixel with i intensity level;

in - number of pixels with i intensity level; We also assume the number of thresholds equal to 1−M , which divide image to

M classes: [ ]11 ,0 tC , [ ]212 ,1 ttC + ,…, [ ]iii ttC ,11 +− ,…, [ ]1,11 −+−

LtC MM . For each of above mentioned classes we can specify probability:

R. Ludwiczuk and P. Mikolajczak / Medical Image Segmentation Hybrid Algorithm 199

∑∈

=

mCiim pω

(3)

as well as mean of class intensity:

∑∈

⋅

=

mCi m

im

piω

μ

(4)

Based on these values we can calculate between-class variance [4];

2

1

2 )( Tmm

M

mB μμωσ −∑=

= (5)

where Tμ stands for mean whole image intensity. Since, variance is a measure of grey levels dispersion around medium, therefore its

high value means that deviation from mean is meaningful. According to this, maximum between-class variance means the best isolation of classes in image. That is why, optimal thresholds vector is such for which between-class variance is maximum:

),...,,(,...,, 1212

1...0

*1

*2

*1

11

−

−<<<≤

−

−

= MBLtt

M tttArgMaxtttM

σ

(6)

Unfortunately, quite meaningful disadvantage of multilevel thresholding by classical Otsu metod is its counting complexity and quite long time of algorithm completion. Ping – Sung Liao, Tse – Sheng Chen i Pau – Choo Chung proposed

alternative formula of this method based on 2' )( Bσ modified between-class variance.

2' )( Bσ . This between-class variance can be denoted as:

22

1121

2 ),...,,( Tkk

M

kMB ttt μμϖσ −∑=

=

−

(7)

Because mean intensity of whole image does not depend on number or value of threshold, is constant, we can skip it and express maximization condition (9) by modified variance (8) as follows:

2

1

2' )( kk

M

kB μϖσ

=

∑= (8)

,...,,)(,...,, 1212'

1...0

*1

*2

*1

11

−

−<<<≤

−

−

= MBLtt

M tttArgMaxtttM

σ

(9)

R. Ludwiczuk and P. Mikolajczak / Medical Image Segmentation Hybrid Algorithm200

which fastens algorithm. Additionally to optimize, values of zeroth-order moment and first-order moment of probability where put into matrices for all possible intensities [4].

As a result we obtain image divided into classes (optimally in statistical terms), where each class has specified statistical values such as probability and mean intensity. These values are input parameters vector for the second stage – MRF simulation.

Markov Random Fields

s

and

set

ov

)

istics. For is a

is a conditional probabilities, they are some local characterdetermining this probabilities we introduce cliques notation. There, clique csubset of S in the way, that every pair of nodes are neighbors. C is a set of allpossible cliques. Figure 1 shows a first and second order neighborhood system and itspossible cliques.

P

is a MarkRandom Fields (MRF) with respect to the neighborhood system N if:

( ) 0>=∀Ω∈

ωω

XP

For every Ss∈ and Ω∈ω :

( ) ( srrssrrss NrXXPsrXXP ∈===≠== ,|,| ωωωω

X

is the set of edges. Two points is and js

are neighbors if they are connected by edge Eeij ∈ . Neighborhood of node s

denoted by sN is the set of nodes which are neighbors of s . Let’ SsNN s ∈= | will be a neighborhood system for G if sNs∉

sr NrNs ∈⇔∈ . Furthermore, to each node of the graph G , we assign a label λ from a finite

of labels Λ . Such an assignment is called a configuration ω with some probability( )ωP , Ω is a set of all possible configuration. Random Field

EWe will define MRF on graphs [1]. Let ( )ESG ,= be a graph where

nsssS ,...,, 21= is a set of nodes and


Figure 1 Neighborhood systems. a) First order neighborhood system and possible cliques; b) second order neighborhood system and possible cliques

Let V be a potential such, that for each subconfiguration Tω it has assign a value ( )ωTV . This potential defines an energy on set Ω as follows:

( ) ( )∑−= ωω TVU (10)

According to Hammersley-Clifford theorem [1], X is a Markov Random Field

with respect to the neighborhood system N if and only if ( )ω=XP is a Gibbs distribution:

( ) ( )⎟⎠

⎞⎜⎝

⎛−== ∑

∈CccV

ZXP ωω exp1

, (11)

where Z is the normalizing constant.

MRF Image Model

For mathematical formulation of MRF image model we define two random fields: SssXX

∈= called label field and RrrFF

∈= called observation field (image

data) [1]. Our goal is to estimate label field form observation field. It is possible by optimizing energy function (10) [2].

MRF Segmentation Model

The argument based on an assumption, that input image is a grey-level image. In generality, it is necessary to find configuration, which maximize a posteriori

probability ( )FP |ω . Bayes theorem tells us that [1], [3]:

a) b)


( )( )

( ) ( )ωωω PFPFP

FP |1| =

(12)

The assumption is, that ( )FP does not depends on configuration and:

( ) ( )∏∈

=

SsssfPFP ωω ||

(13)

(3) and (4) is a foundation for a configuration we are looking for. It can be written as:

( ) ( )( )∏∏∈∈

Ω∈

−=

Cccc

Ssss VfP ωωω

ω

exp|maxarg (14)

On the assumption that ( )ssfP ω| in equation 14 is Gaussian density and each class

Λ∈λ is denoted by its λμ mean value and λ

σ variance. On these assumptions we

get energy function 21 UUU += where [1]:

( ) ( ) ( )∑∈

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛ −+=

Ss

s

s

s

s

fFU 2

2

1 22ln,

ω

ω

ω

σ

μσπω

(15)

( ) ( )∑∈

=

CccVU ωω 22

(16)

( ) ( )⎩⎨⎧

≠

=−==

rs

rsrsrsc if

ifVV

ωω

ωω

β

βωωω ,,2

(17)

where β is model parameter controlling homogeneity of regions. Increase of

homogeneity regions responds to increase of β . Based on above energy function and

Hammersley-Clifford theorem we can point out optimal ω configuration.

Results

Figure 2 presents block scheme of our hybrid algorithm of image segmentation. At the stage of preliminary segmentation we input number of classes and obtain parameters vector being set of mean values and variances of each class. This vector is a set of input parameters for second stage – MRF simulation.


Figure 2 Scheme of hybryd algorithm of image segmentation.

In this work, we use four algorithms for the optimization method of MRF

simulation: Metropolis, Gibbs Sampler, Iterated Conditional Modes (ICM), and Modified Metropolis Dynamics (MMD).

Simulation was realized by using a computer with Intel Pentium Mobile 1.7GHz and 512 MB RAM. For this process we used author’s application. It was created in C++ programming language and Qt library and compiled by GNU g++ under Linux Operating System.

The MRI data of the human head used in this work is obtained from Visible Human Project. Resolution of this images is 256x256 pixels and depth is 1024.

Results of the segmentation for 4 classes are presented in tables 1 and 2 anf figures 3, 4 and 5. Table 1 shows the results of the first step: thresholds values (T1 ,T2 ,T3) and CPU time. We have received these results for different image depth. Table 2 shows results of the second step: MRF simulation by the four optimization methods where T is a temperature. We have received this result for original MRI data obtained form Visible Human Project. Figure 3 presents segmentation results for modified Otsu method, figure 4 presents segmentation results for MRF simulation and figure 5 presents comparison of results .

Table 1 Modified Otsu segmentation results for 4 classes.

Image depth

128 256 512 1024

Para

met

ers

T1 77 77 77 77

T2 184 184 184 184

T3 317 317 317 317

CPU Time 125 ms 1 s 15 s 2 min

Output Image

Input Image

Pre- segmetnation

MRF Image Segmentation

ModelEstimation


Figure. 3 Segmentation results from modified Otsu method on the MR images, a) input image; b) output image.

Table 2 Segmentation results on the MR Image for 4 classes.

Method Iteration Global Energy exp(6)

T CPU Time [ms]

Metropolis 183 1.90129 0.0992 5616.2

Gibbs Sampler 184 1.90129 0.0972 12935.7

ICM 6 1.90132 0.081 573.049

MMD 193 1.9 0.081 4816.54

Figure 4 Segmentation results from hybrid method on the MR images, a) input image; b) output image.

a) b)

a) b)


Figure 5 Segmentation results on the MR images for 4 classes. a) input image; b) pre-segmentation results; c) hybrid segmentation results.

Conclusions

In this paper, a new hybrid method has been developed for the simplification and efficiency of MRF segmentation problem. In this method we include global features of image: histogram; and local features: neighborhood system for MRF simulation. Our hybrid method includes automation of segmentation process but incomplete. In the future, we would like to improve our technique by using the methods of Fuzzy Sets theory. In this case it will be possible for the process of segmentation to be automated and its quality will be much better.

In the nearest future we are going to analyze functional magnetic resonance images (fMRI). We will adopt our method to localize the activity of brain regions. Furthermore, we will create a map of brain functions. It will be helpful in neurosurgery.

References

[1] Z. Kato, Multi-scale Markovian Modelisation in Computer Vision with Applications to SPOT Image Segmentation, PhD thesis, INRIA Sophia Antipolis, France, 1994.

[2] O. Allagnat, J. M. Boucher, D. C. He, and W. Pieczynski, Hidden Markov Fields and Unsupervised Segmentation of Images, In Proc ICPR’92,1992.

[3] C. Bouman: A Multiscale Image Model for Bayesian Image Segmentation, Technical Report TR-EE 91-53, Purdue University, 1991.

[4] P. S. Liao, T. S. Chen, P. C. Chung, A Fast Algorithm for Multilevel Thresholding, Journal of Information Science and Engineering, vol 17, 713-727, 2001.

[5] A. D. Brink, Thresholding of digital images using two-dimensional entropies, Pattern Recognition, Vol. 25, No.8, pp. 803-808, 1992.

a) b) c)


The Influence of Electromagnetic Field Polarization on Interfering Voltage at Cardiac Pacemaker Implanted

into Human Body Model

Arkadiusz MIASKOWSKI1, Andrzej KRAWCZYK2, Andrzej WAC-WLODARCZYK3, Yoshiyuki ISHIHARA4

1Agricultural University in Lublin, Akademicka 13, 20-950 Lublin, Poland, [email protected]

2Cenral Institute of Labour Protection, Czerniakowska 16, 00-701 Warsaw, Poland, [email protected]

3Lublin University of Technology, Nadbystrzycka 38, 20-618 Lublin, Poland, [email protected]

4Doshisha University, Kyotanabe, Kyoto 610-0321, Japan, [email protected]

Abstract. The purpose of this paper is to investigate the interference voltage at cardiac pacemaker which is digitally implanted into the human body model. In order to investigate various exposure scenarios, different plane wave polarizations were applied. This research has been done to find out which kind of wave polarization makes the greatest hazard i.e. the highest value of interfering voltage. The numerical investigation of the coupling model, that is field-to-voltage transfer function, was carried out using the FDTD method.

Introduction

Because the recent worldwide popularity of wireless communication is still increasing there is a high possibility that a human with an implanted cardiac pacemaker might approach a base-station antenna electromagnetic (EM) field area. That is why the aim of this study was to provide a preventive assessment of effects from EM interference with cardiac pacemakers, with special focus on the field generated by base station antennas. If the radiation source is far away from the cardiac pacemaker, like in our case, the environmental influences can be neglected, and for simplification, a homogeneous plane wave can be used for the purpose of describing spatial field distribution from base station antennas.

In order to investigate the influence of electromagnetic wave polarization on interfering voltage, the authors used two kinds of numerical models that is a 3D homogenous model (Fig. 1-left) and 3D realistic high resolution (HR) human model (Fig. 1-right). The first one is a so called flat phantom to whom tissue-equivalent liquid parameters were assigned according to [1] and which was prepared to investigate the influence of the local tissue distribution on the maximum interfering voltage. The second one is based on the Visible Human Project [2] and include 42 different types of


207

biological tissues to which the parametric model describing the dielectric properties of tissues proposed by Gabriel [3] was applied. Moreover, in order to consider the worst case scenario in our HR human model the skin tissue was overestimated by a high conductive muscle tissue. The influence of this substitution was significant, because the highest EM field occurs at the surface of the body [4]. Furthermore, in the authors’ opinion the results of such calculations i.e. using just mentioned two kinds of numerical models can be used in a laboratory setup to validate experimental measurements.

Human Body Models with an Implanted Cardiac Pacemaker

The tissue properties for the flat phantom were identical with those of a muscle i.e. εr = 4.0, σ = 0.2, ρ = 1.04 g/cm3 as described in EN 50361 for 900 MHz [1]. Inside the highly simplified homogeneous human model and inside the HR model, the pacemaker was placed 6 mm deep into the models. The pacemaker housing a case had a dimension of 42 × 52 × 6 mm with a unipolar electrode 560 mm long. The projection area of the pacemaker configuration was 196 cm2. In our FDTD simulation we defined the pacemaker housing case, the electrode and the lead wire as perfect conductors. The CAD model of cardiac pacemaker is shown in Fig. 2.

Fig.1 The numerical models of human ( the flat phantom – left, the HR model – right)

Fig.2 The CAD model of cardiac pacemaker

A. Miaskowski et al. / The Influence of Electromagnetic Field Polarization on Interfering Voltage208

The numerical investigation of the above mentioned problem was carried out using a public domain [5] and commercial software from CST GmbH [6].

Numerical Study of the Coupling Model

The coupling model describes the relationship between electromagnetic field emitted by a field source (in our case a base station antenna), and the interfering voltage at the cardiac pacemaker input port based on realistic implant situation. In our investigation the model is based on the fact that the pacemaker acts like a receiving antenna with respect to the EM field from a base station antenna. The EM field from a base station antenna can be evaluated as the far field region, where the electric field E-strength and the magnetic field H-strength exhibit the same distribution. That is why, the EM field from a base station antenna can be considered as the homogeneous plane wave at twelve different polarizations relative to the body model as shown in Fig. 3. (The same polarizations have been applied to the flat phantom).

Fig.3 Twelve different plane wave polarizations relative to the human body model

Figure 4 shows an equivalent circuit for the pacemaker exposed to the EM field

from a base station antenna, in which the internal impedance looked at from the connector and the housing case of the pacemaker and the lead wire of the electrode are considered as a load of a receiving antenna. ZR is the radiation impedance of pacemaker, V0 is the open-voltage induced between the pacemaker housing case and the lead wire due to the EM field from a base station antenna, Z1 is the internal impedance of the pacemaker looked at from the connector, and V1 is the voltage induced through the connector. The open-voltage V0 , as has been proved experimentally, is proportional to EM interference and can be used as the index for the evaluation of EM interference at the pacemaker [7].

A. Miaskowski et al. / The Influence of Electromagnetic Field Polarization on Interfering Voltage 209

Fig.4 The equivalent circuit for the cardiac pacemaker as the receiving antenna

For the evaluation of the open-voltage V0 at the pacemaker we replaced the

connector with lumped resistor in one FDTD cell, and then we could derive the voltage across the lumped resistor as V0. For example, considering the resistor R being x-directed and voltage V1 across the resistor, the current flowing along it at the (n-1/2) time step is:

2

12/112/1

nx

nx

nn EE

Rx

RVI +Δ

==

−−

−

(1)

where Ex is the electric field component at the resistor, Δx is the cell size in the x direction. The corresponding relation to E-field and H-field at the resistor can be given by:

( )xnnx

nx H

zyRxt

tE

zyRxt

zyRxt

E 2/11

21

21

21

−−

×∇

ΔΔ

ΔΔ+

Δ+

ΔΔ

ΔΔ+

ΔΔ

ΔΔ−

=

ε

ε

ε

ε

(2)

Under the assumption that R >> ZR, the voltage V1 equate with the open-voltage V0.

The Results

The results of the authors’ investigation for the exposure of the cardiac pacemaker to EM field generated by a homogeneous plane wave of an amplitude E = 1 V/m for twelve different polarizations according to the human body models at frequency 900 MHz are listed in Table 1 for the flat phantom, and in Table 2 for HR model.


Table 1. The interference voltages for different scenarios for the flat phantom.

No. Polarization U [V]

1 PEHK 0.0048

2 PEKH 0.003

3 PHEK 0.004

4 PHKE 0.0025

5 PKHE 0.0023

6 PKEH 0.0022

7 MEKH 0.002

8 MEKH 0.006

9 MHEK 0.0013

10 MHKE 0.0053

11 MKEH 0.0015

12 MKHE 0.0011

No. Polarization U [V]

1 PEHK 0.0029

2 PEKH 0.0022

3 PHEK 0.0031

4 PHKE 0.0011

5 PKHE 0.0013

6 PKEH 0.0015

7 MEKH 0.0019

8 MEKH 0.0031

9 MHEK 0.00015

10 MHKE 0.0021

11 MKEH 0.0009

12 MKHE 0.0006

As can be found in Table 1 and Table 2 the highest interfering voltage occur in the

case of frontal incident and vertical E polarization. Moreover, the values for the flat phantom are about three times higher than for the HR model. The analogous situation took place in the evaluation of the influence of the electromagnetic wave polarization on SAR (Specific Absorption Rate) in human body model [8].

Table 2. The interference voltages for different scenarios for the HR model.

A. Miaskowski et al. / The Influence of Electromagnetic Field Polarization on Interfering Voltage 211

Conclusions

The aim of this investigation was to predict possible hazards (pacemaker dysfunctions) in the pre-implementing time. The evaluation such as the presented one should be useful in the development of protection standards of human exposure to EM field with respect to humans with implants such as cardiac pacemakers. Moreover, the authors hope that the conducted investigation could be useful in the adaptation of working conditions in Poland to European Union standards. Furthermore, using the flat phantom in the EM interference tests in a laboratory setup, potential investigators should consider numerical simulation results first and then validate their results from measurements.

This paper has been prepared on the basis of the results of a task carried out within the scope the second stage of the National Programme "Adaptation of Working Conditions in Poland to European Union Standards", partly supported - within the scope of research - in 2005–2007 by the Ministry of Science and Higher Education. The Central Institute for Labour Protection – National Research Institute has been the

Programme’s main co-ordinator.

References

[1] EN 50361, Basic standard for the measurement of Specific Absorption Rate related to human exposure to electromagnetic fields from mobile phones (300 MHz – 3 GHz), CENELEC 2001.

[2] http://www.nlm.nih.gov/research/visible/visible_human.html. [3] S. Gabriel, R. W. Lau, C. Gabriel, The dielectric properties of biological tissues: III. Parametric models

for the dielectric spectrum of tissues, Phys. Med. Biol. Vol. 41, pp 2271-2293, 1996. [4] F. Gustrau, A. Bahr, M. Rittwerger, S. Goltz, S. Eggert, Simulation of Induce Currant Densities in the

Human Body at Industrial Induction Heating Frequencies, IEEE Tran. on Elect. Compatibility, vol. 41, no. 4, pp. 480-486, 1999.

[5] A. Farjadpour, D. Roundy, A. Rodriguez, M. Ibanescu, P. Bermel, J. D. Joannopoulos, S.G Johnson, G. Burr, Improving accuracy by subpixel smoothing in FDTD, Optics Letters, 2006.

[6] www.cst.com. [7] J. Wang, O. Fujiwara, T. Nojima, A model for predicting electromagnetic interference of implanted

cardiac pacemaker by mobile phones, IEEE Trans. Microwave Theory Tech., Vol. 48, pp 2121-2125, 2000.

[8] A. Miaskowski, A. Krawczyk, The Influence of the Electromagnetic Field Polarization on SAR in Human Body Model, Electrotechnical Review, pp 61-62, 5/2006.


Effects of Dielectric Properties on

Radiofrequency Exposure Compliance

Using an Alternative Human Head Model

Maia SAUREN a, 1

, Raymond J. McKENZIE a

and Robert L. McINTOSH a

a

Australian Centre for Radiofrequency Bioeffects Research (ACRBR), Australia

Abstract. Uncertainty exists in dosimetry literature regarding the necessary level

of complexity in anatomical and other detail for computational simulation of

humans for radiofrequency (RF) exposure compliance calculations. Since

anatomic parameters are not easily varied within existing models, we have

proposed an alternative simplified human head model where key factors affecting

Specific Energy Absorption Rate (SAR) are parametrically variable. Populating

the new model with data of anatomic variation in key tissues allows investigation

into what approximations can be used in physical and computational modeling of

SAR and what trade-offs may be made between accuracy and modeling

requirements. Here we present results pertaining to the effect of dielectric

properties of tissues in the human head on calculated SAR using this model.

Keywords: Radiofrequency, Specific Energy Absorption Rate (SAR), dielectric

properties, human, mobile telephones

1. Introduction

Physical models used for Specific Absorption Rate (SAR) compliance measurement

are, for practical reasons, necessarily much simplified (containing only one or two

contiguous tissues), whereas computational models can be far more representative,

incorporating many complex tissues. The SAR produced in such models from a given

source is dependent on several key parameters, including shape and size of the exposed

person, the type, location and size of the tissues considered, and their dielectric

properties. Ramifications of such assumptions on SAR compliance are not well

described in the current literature.

We reason a priori that there may be a reduced set of key tissues in the head which

dominate the resultant SAR distribution and on which compliance considerations

would most critically depend. For example, we expect surface tissues such as skin to

be the site of maximum SAR in the head, while the brain and eyes are likely to be the

most critical organs in the head to be affected by RF exposure. The alternative model

described here seeks to find a compromise in complexity somewhere between the

homogeneous single-tissue model and the multi-tissue models and therefore includes a

reduced set of only the most relevant tissues in a semi-homogeneous, simplified

geometry. An additional advantage of this model is that, in combination with an

1

Corresponding Author: Maia Sauren, ACRBR, RMIT University, School of Electrical and Computer

Engineering, GPO Box 2476V, Melbourne VIC 3001, Australia; E-mail: [email protected]


213

appropriate computational modeling platform, it allows for easy parametric adjustment

of tissue size, relative location, dielectric properties and morphology. Such adjustments

are difficult to achieve using complex realistic models such as Visible Human (VH)

(available from Brooks Air Force), which consist of many complex three-dimensional

shapes. Within the proposed model, it is possible to vary the chosen key tissues

according to the range of human anatomical differences, gathered from available

literature, to observe the effect of natural variation in human anatomy and tissue

properties on SAR. Using this model, we have begun to investigate [1-2] what

approximations can be used in physical and computational modeling of humans for

SAR calculations; and what trade-offs can be made between accuracy and modeling

requirements for practical considerations. Key issues being investigated are how SAR

varies between children and adults, between males and females, and across ethnic

populations. We present here some of our results pertaining to the effects on SAR of

the permittivity and conductivity of tissues in the head.

Various authors outline measurements of dielectric properties of human tissues [3],

or mathematical models used to predict such properties at various frequencies [4],

though only a few such as [5] and [6] have tested the effects of these properties on

SAR. Fujiwara et al [7] approximated the electrical properties of skin using Debye

dispersion characteristics at 1.5 GHz, and noted that permittivity of skin is about 10%

lower, and conductivity about 30% lower, than previous estimates. The uncertainty in

estimates of human tissue dielectric properties is a source of uncertainty in the resultant

SAR calculations. Keshvari et al [8] varied dielectric properties of tissues in existing

models by up to 20% and observed variation of up to 5% in computed SAR. We

propose to extend the work of these authors, taking advantage of the utility of our

model to expedite a more wide ranging exploration of the effect of dielectric properties

of tissues, and their uncertainties, on SAR.

2. Method

Figure 1. Geometry Man, a simplified parametric model of the human head. Key tissues include skin, skull,

brain, eye, fat and ear. The rest of the model, termed ‘filler’ in this paper, comprises of an average head tissue

compliant with IEEE P1528 [10].

M. Sauren et al. / Effects of Dielectric Properties on Radiofrequency Exposure Compliance214

A simplified model of the human head termed Geometry Man has been constructed

(Figure 1), initially based on anatomic measurements taken from a large sample of

adult Caucasian males [9]. Six key tissues have been chosen for incorporation into the

model: skin, skull, brain, eye, and ear, as these are a priori considered to be most

significant for the determination of the SAR distribution. A 7 mm layer of fat surrounds

both eyes, as in the human body; electrically isolating the tissue. The remainder of the

model (termed ‘filler’ in this paper) is comprised of an average head tissue, compliant

with IEEE P1528 [10]. The shapes in this model may be varied parametrically, greatly

reducing the effort required to undertake this extensive modeling task.

A comprehensive review of the current literature has been used to obtain an

estimate of variations in a set of anatomical parameters affecting SAR - tissue

dielectric, size, thickness and relative location. For tissue size, thickness and location,

this review allowed the determination of a set of parameters representing the mid-value

(50th

percentile) of the human population, which has been used to refine the Geometry

Man model. Due to the scarcity of data regarding dielectric properties, the mid-values

were taken to be as described by Gabriel [11] and then varied to ±10, ±20 and ±30 per

cent (see Table 1 for complete data), to simulate a population distribution, based on the

assumption of an approximately linear association with SAR in infinite homogenous

lossy layers and the observation that a variation for SAR of 30% is an accepted

uncertainty in SAR measurement standards [12].

Table 1. (a) Conductivity (σ) and (b) permittivity (ε) properties used in this study. Gabriel values [12] were

varied to ±10, ±20 and ±30 per cent.

(a) Tissue 70% 80% 90% 100% 110% 120% 130%

Brain 0.54 0.62 0.69 0.77 0.85 0.92 1.00

Skull 0.17 0.19 0.22 0.24 0.26 0.29 0.31

Skin 0.61 0.70 0.78 0.87 0.96 1.04 1.13

Eye 1.15 1.31 1.48 1.64 1.80 1.97 2.13

Eye fat 0.04 0.04 0.05 0.05 0.06 0.06 0.07

Filler 0.68 0.78 0.87 0.97 1.07 1.16 1.26

(b) Tissue 70% 80% 90% 100% 110% 120% 130%

Brain 32.06 36.64 41.22 45.8 50.38 54.96 59.54

Skull 11.62 13.28 14.94 16.6 18.26 19.92 21.58

Skin 28.98 33.12 37.26 41.4 45.54 49.68 53.82

Eye 48.23 55.12 62.01 68.9 75.79 82.68 89.57

Eye fat 3.78 4.32 4.86 5.4 5.94 6.48 7.02

Filler 29.05 33.2 37.35 41.5 45.65 49.8 53.95

M. Sauren et al. / Effects of Dielectric Properties on Radiofrequency Exposure Compliance 215

Mathematical modeling is performed using FEKO, a commercially available finite

element method/method of moments (FEM/MoM) software package which is able to

take advantage of the parametric nature of this model [13]. Plane wave excitation in the

saggital plane is used as the source at 4.5 W/m2

, the ICNIRP reference level at 900

MHz for public exposure [14]. Studies using physical human phantoms have been

conducted for validation purposes at the Ericsson Research Laboratory in Sweden.


Figure 2 shows resultant averaged SAR for the entire Geometry Man head (whole head

average, WHA) where tissue permittivity and conductivity were varied as per Table 1.

WHA SAR decreases approximately linearly with increased conductivity of skin,

where highest SAR of 0.037 W/kg is found at lowest conductivity value, σ=0.61 (an

increase in SAR of 5%). The inverse is true of permittivity, where highest WHA SAR

of 0.038 W/kg is found at ε=53.82, 130% of Gabriel value, a SAR increase of 2%. For

the more dominant tissue groups (by mass) such as brain and filler tissue, the opposite

correlation is apparent. Highest WBA SAR is seen at highest conductivity (0.037

W/kg, 1% variation) and minimum permittivity (0.038 W/kg, 2% variation) for both

brain and filler tissues respectively, as would normally be expected in an infinite lossy

layer. The smaller tissue masses, such as eye and eye-fat have little effect on WHA

SAR.

Figure 2. Averaged SAR for the entire Geometry Man head (whole head average, WHA), where each

tissue’s (a) conductivity and (b) permittivity varied as per Table 1. Log-linear scale is used throughout this

paper.

(a) (b)


Figure 3. (a), (b) 1-gram and (c), (d) 10-gram spatial peak SAR in the Geometry Man model for all

dielectric property variations. Also shown in (c) and (d) are the 10-gram average SAR calculated in Visible

Human and NORMAN models, and the exposure limit for general public in the head and torso [14] (2 W/kg

over a 10-gram volume averaged cube).

Figure 3 shows the peak spatial 1-gram and 10-gram averaged SAR for variations

in tissue dielectric properties in the Geometry Man model, with 10-gram SAR for VH

and NORMAN, and ICNIRP general public RF exposure limit [14], shown in (c) and

(d). On the whole, little effect is seen in averaged SAR, with notable exceptions for

dielectric variations in the brain tissue. High 1-gram averaged SAR values are seen at

low conductivity (0.331 W/kg at σ=0.54, 0.238 W/kg at σ=0.62, 70% and 80% of

original value respectively) and high permittivity (0.230 W/kg at ε=59.54, 130% of

original value). The 10-gram spatial peak SAR graphs show corresponding peaks at

low conductivities, highest at 0.209 W/kg. SAR values obtained using the Geometry

Man model are comparable with VH and NORMAN values and are well below the

ICNIRP exposure limit (2 W/kg). The Geometry Man model does not include a body

(whereas VH and NORMAN do) and we would expect higher SAR results for a whole

body model. Whilst not detailed in this paper, we have found that SAR results will be

no more than 50% in any case.

(a) (b)

(c) (d)


Figure 4. (a), (b) 1-gram and (c), (d) 10-gram spatial peak SAR in the brain tissue for all dielectric property

variations. (c) and (d) also show the maximum permitted 10-gram spatial peak SAR for public exposure, and

peak 10-gram volume averaged SAR calculated in VH and NORMAN models.

We have also examined the peak 1-gram and 10-gram averaged SAR in the brain

tissue (see Figure 4) as this is an area of interest (ICNIRP exposure limit [14] and 10-

gram averaged SAR values for NORMAN and VH models also shown in (c)and (d)).

Again, only the brain tissue’s dielectric properties are seen to significantly affect

volume averaged SAR, with trends towards increased SAR at low conductivity (highest

SAR of 0.230 W/kg and 0.167 for 1-gram and 10-gram volume averages respectively)

and high permittivity (0.214 W/kg and 0.140 W/kg are highest 1-gram and 10-gram

SAR values respectively). An unexpected rise in SAR is seen at higher brain

conductivity values.

Overall, the contrasting correlations between WHA SAR and spatially averaged

SAR suggest that as absorption in the surface layers increases (high skin conductivity

and high peak spatial SAR), a resultant shielding effect occurs for the rest of the head,

(a) (b)

(c) (d)


producing a lower WHA SAR. We also note that our results are in agreement with

Keshvari et al’s assessment that dielectric properties have little effect on SAR over the

range of human population variation, and in the context of other large uncertainties in

the data which contribute to the overall result. Variations in SAR seen here are well

below those permitted by the SAR measurement standard [14] for compliance

assessment of mobile phone handsets, and therefore are not likely to contribute

significant error to such compliance assessments. Refinements of this model continue.

4. Conclusions

A simplified, parametrically adjustable model of the human head has been used here to

test the effect of changing dielectric properties of various tissues in the head on the

computed whole head averaged and peak spatial averaged SAR in the entire model and

the brain tissue. Our analysis suggests conductivity plays a greater part in affecting

SAR, both in whole head average and 1-gram spatial averaged values but is more

commensurate with that of permittivity for the 10 g spatial averaged results. However,

neither whole head averaged nor peak spatial averaged SAR is overly affected by

changes in dielectric properties (at least in the context of other uncertainties in the data

that contribute to the overall result), being approximately linearly related over the range

±10-30% as tested here. The work has also again demonstrated the utility of the

Geometry Man concept for relatively expedient investigation of human variation in

anatomical and dielectric properties and its effect on computed SAR.

5. Acknowledgements

This study is funded by the National Health and Medical Research Council (NHMRC),

Australia.

6. References

[1] M. Sauren, R. McKenzie, R. McIntosh, 'Effects of Dielectric Properties on Radiofrequency Exposure

Compliance Using an Alternative Human Head Model', Progress In Electromagnetics Research

Symposium (PIERS) 2007, August 27–30, 2007, Prague, Czech Republic

[2] M. Sauren, R.J. McKenzie, R.L. McIntosh (2006), 'Determining the Influence of Adult Skin Thickness

on Compliance with Radiofrequency Exposure Limits', World Congress on Medical Physics and

Biomedical Engineering 2006 (WC2006), Aug 27 - Sep 1, 2006, Seoul, Korea.

[3] R. Pethig, "Dielectric properties of body tissues," Clin Phys Physiol Meas, vol. 8 Suppl A, pp. 5-12,

1987.

[4] S. Khalafalla, L. Turner, and D. Spyker, "An electrical model to simulate skin dielectric dispersion,"

Comput Biomed Res, vol. 4, pp. 359-73, 1971.

[5] Drossos, V. Santomaa, and N. Kuster, "The dependence of electromagnetic energy absorption upon

human head tissue composition in the frequency range of 300-3000 MHz," IEEE Transactions On

Microwave Theory And Techniques, Vol. 48, pp. 1988-1995, 2000.

[6] Christ and N. Kuster, "Eifferences in RF energy absorption in the heads of adults and children,"

Bioelectromagnetics, vol. 7, pp. s31-s44, 2005.

[7] O. Fujiwara and K. Takai, "Electrical properties of skin and SAR calculation in a realistic human model

for microwave exposure," Electrical Engineering In Japan, Vol. 120, pp. 75-80, 1997.


[8] J. Keshvari, R. Keshvari, and S. Lang, "The effect of increase in dielectric values on specific absorption

rate (SAR) in eye and head tissues following 900, 1800 and 2450 MHz radio frequency (RF) exposure,"

Phys Med Biol, vol. 51, pp. 1463-77, 2006.

[9] L. G. Farkas, Anthropometry of the head and face, 2nd ed. New York: raven press, 1994.

[10] IEEE, "IEEE P1528: Recommended practice for determining the peak spatial-average specific

absorption rate (SAR) in the human head from wireless communications devices: Measurement

techniques," Piscataway, NJ 2005.

[11] Gabriel C, "Compilation of the Dielectric properties of body tissues at RF and microwave frequencies",

Brooks Air Force Base, report no. AL/OE-TR-1996-0037, 1996.

[12] ANSI/IEEE, “IEEE Standard for Safety Levels with Respect to Human Exposure to Radiofrequency

Electromagnetic Fields, 3 kHz to 300 GHz”, ANSI/IEEE C95.1-1992 (see http://standards.ieee.org/cgi-

bin/status), 1992

[13] http://www.feko.info, "EM Software & Systems" [as at July 2007]

[14] Australian Radiation Protection and Nuclear Safety Agency, “Radiation Protection Standard for

Maximum Exposure Levels to Radiofrequency Fields - 3 kHz to 300 GHz (2002)”


Finite Element Dosimetry of Power Frequency Induced Currents

into the Human Body by Using Quasi-static Zooming

Riccardo SCORRETTI, Le Ha HOANG, Nöel BURAIS , Alain NICOLAS Université de Lyon, Lyon, F-69622, France ; Université Lyon 1, Lyon, F-69622,

France ; CNRS, UMR5005, Laboratoire AMPERE, Villeurbanne, F-69622, France, [email protected]

CEDEX, France, [email protected]

Abstract. Electrical currents, induced into the human body by power-frequency magnetic fields, are computed by using the Finite Element method. The resolution is increased in a small region of major interest (brain, heart) by using a zooming method. Applications with simple sources of the exciting fields, as well as realistic power systems are presented.

Keywords. Finite Element, computer dosimetry

Introduction

Finite Element (FE) can be effectively used to compute induced currents into the human body by power-frequency magnetic fields. The main drawback of this method, compared to Finite Difference Time Domain method (FDTD), is the low resolution of the anatomical models. So as to improve the resolution, we apply the quasi-static zooming technique, which allows to refine the computation in a target region, which has to be “small enough”, compared to the size of the body and to the wavelength of the field. This technique, which was originally developed to model electrical appliances [1-3], has been more recently applied in the high frequency domain by Van de Kamet et al to the computation of the SAR in the human body by using the FDTD in the context of mobile communications [4] and of hyperthermia treatment [5].

1. Numerical Formulation

The induced currents into the human body by a power frequency magnetic field are computed by FE by using the well known φ-A formulation [6,7]. The main assumption of this formulation is that the perturbations on the source field B (dues to the induced currents into the body) can be neglected. Therefore one can assume that this field is known by a vector potential, namely AB ×∇= . This vector potential A can be

1 CNRS, UMR5005, Laboratoire AMPERE, Ecole Centrale de Lyon, 69134 Ecully

1


221

obtained by any kind of computation (Finite Element, analytical formulas, etc.) performed in absence of the human body. One obtains the following expression of the electric field E and of the current density J :

E B E At t φ∇× = −∂ ⇒ = −∂ −∇ (1)

( )φσσ ∇+∂−== AEJ t (2)

where the electric scalar potential φ is the unknown of the problem, and σ is the conductivity [8]. By imposing the charge conservation, one obtain the main differential equation, which is imposed inside the human body (displacement currents can be neglected at power frequencies) :

( )[ ] 0=∇+∂⋅−∇=⋅∇ φσ AJ t (3)

Hence, the problem of computing eddy currents is converted into a conduction problem. At the boundary of the human body, we impose the following boundary condition :

0=⋅nJ (4)

which in practice means that no current flows out of the body. Equations (3) and (4) are rewritten in the so called “weak form” by using Galerkin’s method. The problem can be then stated as following : “Find the continuous electric potential φ such that:

( ) ( )1A 0 Hw j wσ ω φ

Ω

⎡ ⎤∇ ⋅ +∇ = ∀ ∈ Ω⎣ ⎦∫∫∫

where Ω is the human body, and ( )1H Ω is the space of functions :w Ω a

continuous and derivable. This equation is solved by FE onto an anatomical model of the whole body (76’000 nodes). 17 different organs are represented, each of one with its own conductivity. Only one unknown per node is required by this formulation.

2. The Quasi-Static Zooming

So as to increase the resolution in a particular zone of the body which has a major importance, we apply the quasi-static zooming. The main idea of this technique is that, due to the “smoothing” behaviour of diffusion phenomena (like quasi-static electric conduction), the influence of fine details of the geometry is quickly attenuated, and it is hardly observable at a “reasonable” distance. Hence, it should be possible to refine the result obtained on the whole body by using a more detailed model of the “interesting” part of the body. In practice, we have made a more detailed model of the head (fig. 2D) and of the trunk, due to the major importance of these parts of the body. These models are composed of

R. Scorretti et al. / FE Dosimetry of Power Frequency Induced Currents into the Human Body222

respectively 122’000 and 176’000 nodes, which is more than twice compared to the model of the whole body. In the first step, we solve the problem (5) on the “coarse” model of the whole body. In further steps, we solve the same problem (5) by FE on each restricted domains. So as to impose the continuity between the whole body and the refined domains (i.e. head and trunk), the electric potential φ obtained in the first step is evaluated at the junctions body / head and body / trunk, and it is imposed as Dirichlet boundary condition. Therefore, we obtain a solution which is reasonably better than the one obtained with the coarse model.

3. Validation

Our computational code is being developed by using both MATLAB and C languages. The validation of the code itself can be found in [6], where we have compared the results provided by our code with both analytical solution and numerical computation obtained with the commercial software FLUX3D. Also, we have checked on small size models (for which a coarse and refined mesh of the whole model is available) that the quasi-static zooming improves the accuracy of the results, for values of conductivities comparable to those of living tissues (not shown).

Then, we have compared the results obtained with our code and human body model with the results provided in literature [9]. The table I reports the r.m.s. values of the uniform magnetic flux density which (at 60 Hz) induce an average (maximum) value of 1 mA/m2 into the whole human body (cf. table 2, pag. 2325 of ref. [9]). The comparison between our results and the ones which can be found by the group of Dawson is excellent. In figure 1, we show the average (maximum) current density obtained in different organs, under the same conditions (that is, average whole-body (maximum) current density = 1 mA/m2 at 60 Hz). The filled bars are obtained with the coarse model, whereas the white bars present the refined data by using quasi-static zooming. One observes that in most cases the quasi-static zooming does not modify substantially the average values, which is an encouraging sign of self-consistence of our modelling. The cases of eyes and spinal chord, where some discrepancy between the coarse and refined results is observed, can be explained by the small size of these organs: in this case, the zooming is logically expected to provide the more reliable result. Again, these data agree rather well with the results provided in literature (cf. fig. 2d pag. 2324 of ref.[9]).

Table 1. r.m.s. values of the uniform flux density which at 60 Hz produce a whole-body average (maximum) current density of 1 mA/m2

Orientation Flux density [mT r.m.s.]

( provided in [9] )

Flux density [mT r.m.s.]

( computed by our code )

Bx 0.3596 0.3536

By 0.2946 0.2732

Bz 0.4282 0.4139

R. Scorretti et al. / FE Dosimetry of Power Frequency Induced Currents into the Human Body 223

Fig.1. average (maximum) current density induced in different organs at 60Hz by a uniform magnetic field (see table 1 for the magnitudes of the exciting magnetic field). These values are obtained by using the coarse model of the whole body (filled bars) and the quasi-static zooming (white bars).

4. Example: Hardening of a Metal by Induction Heating

As example of realistic power system, we present here the case of an induction heater for hardening the surface of metal. The system is composed of a metal tube, which is heated by a 30 kHz inductor (current NI = 5·200 A r.m.s). The worker is standing at about 30 cm from the inductor, and he is protected by a metallic shield. The source magnetic potential A is computed in absence of the human body by using FLUX3D. Figure 2 shows the exciting (source) magnetic field, and the induced current into the whole body and the details of the brain obtained by the coarse model, and the refined computation by using the quasi-static zooming. The distribution of induced current is not intuitive : the peak of the current is located far from the peak of the magnetic field (cf. fig. 2A and 2B). One observes that the zooming allows to obtain a much more detailed computation in the brain (cf. fig. 2C and 2D) at a moderate cost, compared to more classical FE or FDTD.


Fig.2. A) Excitation field and B) induced current density in the whole body by an industrial induction heater working at 30 kHz. C) Current density in the brain computed with the coarse model, and D) refined computation. Astonishing, the peak of induced current is not located close to the peak of the excitation field.

B) C)

D)

R. Scorretti et al. / FE Dosimetry of Power Frequency Induced Currents into the Human Body 225

References

[1] T. W. McDaniel, R. R. Root, A technique for resolution amplification in three-dimensional field

calculations for recording media, IEEE Trans. Mag. Vol. 17(6), pp. 3411-3413, November 1981.

[2] O. Fabregue, L. Krähenbühl, L. Nicolas, A numerical zoom for 3D modelization of complex devices,

Proc. of the COMPUMAG 1991, Sorrento, Italy.

[3] H. Kwon, M. H. Wahl, F. E. Talke, Finite Element simulation of a helical scanner with head/tape

contacts, IEEE Trans. Mag. Vol. 32(5), pp. 3735-3737, September 1996.

[4] J. B. Van de Kamer, J. J. W. Lagendijk, Computation of high-resolution SAR distribution in a head due

to radiating dipole antenna representing a hand-held mobile phone, Phys. Med. Biol. Vol. 47, pp. 1827-

1835, 2002.

[5] J. B. Van de Kamer, A. A. C. De Leeuw, H. Kroeze, J. J. W. Lagendijk, Quasistatic zooming for

regional hyperthermia treatment planning, Phys. Med. Biol. Vol. 46, pp. 1017-1030, 2001.

[6] R. Scorretti, N. Burais, O. Fabregue, A. Nicolas, L. Nicolas, Computation of the induced current

density into the human body due to relative LF magnetic field generated by realistic devices, IEEE

Trans. Mag. Vol. 40(2), pp. 643-646, March 2004.

[7] T. W. Dawson, M. A. Stuchly, High-resolution organ dosimetry for human exposure to low-frequency

magnetic fields, IEEE Trans. Mag. Vol. 34(3), pp. 708-718, May 1998.

[8] S. Gabriel, R. W. Lau, C. Gabriel, The dielectric properties of biological tissues: II. Measurements in

the frequency range 10 Hz to 20 GHz, Phys. Med. Biol. Vol. 41, pp. 2251-2269, 1996.

[9] T. W. Dawson, K. Caputa, M. Stuchly, A comparison of 60 Hz uniform magnetic and electric induction

in the human body, Phys. Med. Biol., Vol 42, pp. 2319-2329, 1997.


Chapter 5

Electromagnetic Field in Standards and

Policy

Electromagnetic Fields Measurements – Methods and Accuracy Estimation

Pawel BIENKOWSKI Wroclaw University of Technology, Poland

[email protected]

Abstract. The paper presents theoretical analyses and measurements results of factors affecting the precision of survey EMF measurements. Presented problems are connected mainly with errors of a method and imperfection of the measuring device. In particular: using probes with non-zero geometrical dimensions, difference between conditions of calibration and measurement (eg. modulated and pulse fields), uncertainty of calibration, nonlinear dynamic characteristic and frequency response and “human factor”.

Keywords. Electromagnetic metrology, survey measurements, uncertainty

Introduction

The development of contemporary civilization is associated with the consumption of more and more quantities different forms of energy. One of the forms of energy, which role has been rapidly growing in every branch of everyday life, is energy of RF currents and fields. The intentional or unintentional irradiation of a part of the RF energy, which results in contamination of the whole environment and the interference in wide frequency range is take place in those processes. Because of the fact that the electromagnetic field is not detectable by organoleptic methods, EMF detection and every works and investigations connected with the field require the use of the specific tools to detect it.

EMF measurement in the far-field (Fraunhofer zone) is one of the less accurate as compared to measurements of other physical quantities. The near-field conditions (Fresnel region) cause further degradation of the near-field EMF measurements accuracy as compared to the far-field one. An additional problem is the accuracy of the EMF standards and as a result low accuracy of measurement devices.

1. EMF Measurement Methods

Generally EMF is described by electric field vector - E, magnetic field vector - H and Poynting's vector S, but only in the limited level. In the far field these vectors are strictly connected by the impedance of free space. In the near source fields their relations are more complicated and depend on the type of EMF source and distance from source to sensor. In more general situations and completely unknown fields (especially in the primary and secondary EMF sources proximity) the E and H field strength must be measured separately.


229

In order to optimally select a method of the EMF measurement in the near-field it is initially necessary to find quantities that would characterize the field in the best way and would be possible to use in a practical application. The dominating technique of EMF measurement is the use of an antenna (mainly a symmetrical dipole for E-field and a loop for H-field) loaded by a detector (diode or, more rarely, thermocouple) with lowpass filter and transfer of DC voltage from the probe to an indicator (in the case of the most popular designs of two-piece meters) through a high resistance (transparent) transmission line. There are usually wideband probes. There are some restrictions in using antennas as an EMF probes.

2. Geometrical Size of Antennas

Every EMF measuring probe causes the measured EMF integration by finite sizes of a probe. In the case of the far-field measurements the integration is usually negligible as the probe standardization is done in similar conditions as measuring ones. The near-field probes are standardized in similar conditions (in a TEM cell, on an open site) and then the change of the measuring conditions to those during standardization must be taken into account. The EMF integration may be divided into two phenomena, i.e.: the phase integration and the amplitude integration [1,2].

The phase integration is based upon a current distribution in a measuring probe and the phase integration error δp may be defined in the form (1):

δp = 12

1 2khsin 2kh

−⎛

⎝⎜

⎞

⎠⎟

(1)

where: k - propagation constant, 2h - probes length.

In order to make it possible to compare the measuring band of limiting factors the formula is plotted in Figure 1.

0.1 0.2 0.3 0.4 0.5 0 .6

-40

-20

02h /λ

δ p

[%]

Figure 1. Phase integration error versus 2h/λ

The error presented supports the widely accepted point that the measuring antenna

(for the near-field purposes) should be 'electrically small'. It may be seen from the diagram that this means that the antenna length should not exceed, say, 0.2λ. It is not necessary to call the power line frequency example to show the role of the limit at microwave ones (which are here of concern).

P. Bienkowski / Electromagnetic Fields Measurements – Methods and Accuracy Estimation230

To illustrate probes' size limitations at lower frequencies we should take into account the amplitude integration error δa. The error depends upon the EMF curvature. If present, for instance, the electric (E) field in the near-field in the form (2):

E constR

=α

(2)

where: R - distance between a source and a probe, α - wave type indicator. For spherical wave α = 3, for the plane one (TEM wave) α = 0 and analyzed error

disappears. The error as a function of 2h/R, for three values of α is plotted in Figure. 2.

0 .4 0 .8 1.2 1.6

60

40

20

0

[%]

2h/Rα=1

α=2

α=3

δ p

Figure 2. Amplitude integration error versus 2h/R

It may be summarized that δ

p play the main role in high frequencies and δ

a in

measurements in source proximity, independent of frequency range. For magnetic field measurement one usually uses probes consisting of a circular

loop antenna loaded with a detector of shaped frequency response. Analogically to electric field it is possible here to follow the discussion related to the measuring antenna sizes limitation, which results from the error of a quasi-point value of the magnetic field measurement and the results are almost the same.

3. EMF Probe Frequency Response

The structure of a typical E-field broadband probe and its equivalent circuit is presented in Figure 3.

high resistive line RCCp+fea Um

Ca LpRf

Figure 3. Structure and equivalent circuit of wideband E-field sensor

P. Bienkowski / Electromagnetic Fields Measurements – Methods and Accuracy Estimation 231

Source ea represents the voltage induced in the antenna. The voltage value depends on field intensity E in the measurement site and on the effective height of the antenna hef (3):

ska hEe ⋅= (3)

For the electrically short dipole (2h<0.1 λ) the effective height is a constant in the frequency function and equals the half of the geometrical length of the antenna. Its input impedance is purely of the capacitance nature. The input signal of the detector, simultaneous to the voltage at antenna load equals (4):

)()()()(

0

00 fZfZ

fZefUa

a+

⋅= (4)

where: U0 – voltage in load impedance, Za – input impedance of the antenna, Z0 – load (detector and monitor) impedance

In Figure 3 impedance Za = Ca , Z0 are represented by C, R, Cp+f and Lp. C and R are detector parameters, Cp+f and Rf are the elements of the low-pass filter that allows modification of the probes’ frequency characteristic, especially in high frequencies to reduce an influence of fields from beyond of probe measuring band causing parasitic reactance of probe elements that are connected with parasitic capacities and inductances related to the montage and imperfections of the elements. As a result probe sensitivity rapidly increases near resonance frequency. It will only mention here that the measuring band of the probe must be artificially limited to frequencies below resonance of these reactances and the resonance of the antenna (very important in loop antennas). Results of use high frequency filter is presented in Figure 4.

10 4 10 5 10 8 10 9 10 10 10 110.1

1

10

f[Hz]

|T|

Figure 4. Frequency responses of E-field probe without- (dashed line) and with RC filter. Analysis circuit from Fig. 4 in the frequency function allows distinguishing three

typical sub-ranges: −−−− low frequency range, in which transmittance increase with frequency −−−− medium frequency range, in which transmittance is a constant:


fpa

a

CCCCfU

+++

≅)( (5)

(This range is the most interesting one from the metrological and practical point of view.)

−−−− high frequency range, in which the influence of the antenna filter is visible and where the transmittance decreases while the frequency increases.

By changing the values of particular elements of the probe, we can modify both the

shape of the frequency characteristic and the values of transmittance, having a direct influence on sensitivity of the system [3].

Examples of frequency response of different commercial E-field probes are presented in Figures 5 and 6.

-202468

1012

Cf[dB]

0,1 1 10 100 1000f [Mhz]

Figure 5. Measured frequency response of E-field probe 0,1MHz-1GHz

-5

0

5

10

15

1 10 100 1000 10000

Cf[dB]

f [MHz]

Figure 6. Measured frequency response of E-field probe 1MHz-40GHz, Typically deviation from flat frequency response is from ±0.5dB in kHz and MHz

up to ±5dB in GHz range. Of course it is possible to use frequency correction factor in measurements, but it is difficult or even impossible eg. where fields from different sources working on different frequencies are measured simultaneously.


4. Dynamic Characteristic of EMF Probes

Dynamic response of passive EMF sensors depends on used detector characteristic. For typically used diode detector, the probe’s dynamic characteristics consist of three segments:

−−−− square-law characteristic for low measured field intensity. In this area it is RMS detector;

−−−− transitional characteristic for medium field intensity (characteristic changes from square-law to linear);

−−−− linear characteristic for high intensity, where can be observed the peak detection. Dynamic characteristic changes are negligible when monochromatic harmonic

fields are measured (this complies with calibration conditions), but it is very important in measurements of the complex (eg. multifrequency source) and pulsed fields [4]. It is possible to prove that in square-law area measured effective field intensity can be estimated as (6):

∑=

nnw EE 2 (6)

where: Ew – effective intensity of E or H-field, En – field intensity of n

Typically RMS detection is only for 15-30% of probe’s measuring range. The

results of experiment carried out to check this thesis are presented in Table 1. In laboratory conditions measured signal from two EMF sources 900MHz and 1800MHz were simulated. Measurements were performed in three conditions: works only 900MHz source, works only 1800MHz source and both of them work simultaneously. The error of RMS measure was defined as (7):

[dB] lg202

18002900

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

+=

MhzMhz

wrms

EE

Eδ (7)

Table 1. Results of complex E-field measurement

probe 0.3-3 GHz probe 0,01-3 GHz E900M

[V/m] E1,8G

[V/m] E900+1800

[V/m] Erms

[V/m] δδδδrms [dB]

E900M

[V/m] E1,8G

[V/m] E900+1800

[V/m] Erms

[V/m] δδδδrms [dB]

3,4 3,4 4,8 4,8 0,00 5,2 3,8 6,4 6,4 0,09 5,1 5,1 7,3 7,2 0,04 7,5 5,5 9,5 9,3 0,16 8,3 8,3 11,8 11,7 0,05 12,2 9,0 15,5 15,2 0,16 11,6 11,6 16,6 16,5 0,06 17,9 12,9 22,5 22,1 0,17 16,8 16,8 23,9 23,8 0,04 24,7 18,5 33,3 30,9 0,66 24,2 24,2 34,6 34,2 0,10 36,0 27,4 50,0 45,2 0,87 45,5 45,5 64,7 64,4 0,04 56,7 56,7 92,7 80,2 1,26 69,5 69,5 100,0 98,2 0,15 103,0 66,0 142,5 122,3 1,33


The error δrms as a function of indicated E field intensity for three commercial available probes is plotted in Figure 7.

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

δδδδrms[db]

0 20 40 60 80 100 Erms[V/m]

Figure 7. No-RMS error of three different type EMF probes The next problem connected with no-rms detection is probe’s response for pulse

fields. Theoretically simulation and experiments results show that pulse response depends on detector characteristic and time constant of all measurement system (probe and monitor). Figure 8 presents example results of measured probes response for pulse CW signal with pulse duration from 1% to 100% (pure CW). Experiment carried out for pulse repetition 217 Hz and for 20V/m of CW field strength. The error δpulse was defined as (8):

[dB] lg20 ⎟⎟⎠

⎞⎜⎜⎝

⎛=

RMS

indrms E

Eδ (8)

where: Eind – field strength indicated by the meter Erms – RMS value of pulse field strength

-2,0

-1,5

-1,0

-0,5

0,0

0,5

1,0

1,5

2,0

δ δ δ δpulse[dB]

1 10 100τ τ τ τ [%]

XX-1

XX-2

XX-3XX-4

XX-5

Figure 8. Error δpulse of pulse field measurement for five different type of EMF probes


5. Human Factor

“Human factor” is a factor defined by author as an influence of skills, experiences and perfection of person performing the measurements upon their results [5]. There is practically impossible to calculate this factor theoretically, but it can be estimated on the ground of experimental results. Good opportunity to perform experiments is interlaboratory comparisons programs (ILC/PT). Figure 9. presents results of experiment performed during one of ILC/PT coordinated by author. All participants measured EMF strength in one point established by the organizer in the same conditions and used the same meter.

0,7

0,8

0,9

1

1,1

1,2

1,3

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Number of participant

E/E m

ean

Figure 9. Scatter of measurements results due to “human factor”

Table 3 presents results of additional experiment. In the laboratory conditions

series of special measurements were done. Four men have done two series of measurements using two different EMF meters (all of participants used the same meters). The EMF source was specially prepared. There was 433MHz generator and power amplifier loaded with LPD antenna. Measurements took place in 5 points located 1-3 meters from the transmitting antenna. Three of them were placed in free space, two – ca. 20 cm from a metal surface.

Table 3. Results of the laboratory experiment

Serie I Serie II

Point 1 2 3 4 Emean δδδδ(min-max) [%] 1 2 3 4 Emean δδδδ(min-max)

[%] 1 14,9 16,5 17,6 15,5 16,1 8,3 16,6 15,8 14,2 16,9 15,9 8,7 2 17,6 16,2 18,5 19,0 17,8 8,0 16,5 16,5 19,2 18,5 17,7 7,6 3 9,2 7,3 6,6 8,8 8,0 16,5 5,8 8,8 8,2 6,1 7,2 20,5 4 9,1 8,2 10,2 8,2 8,9 10,9 9,6 10,4 9,9 8,6 9,6 9,5 5 9,9 10,2 11,6 11,0 10,7 7,9 11,0 10,4 14,0 10,4 11,5 14,8

In the both presented experiments the power of EMF source was controlled and all

measurements were done with the same meters, after that it was possible to say, that “human factor” was the main reason of scattered measurement results.


Based on presented results and laboratory practice one can estimate the importance of this factor to be a 1/3 ÷ 1/2 of the total uncertainty of measurements and it leads to the conclusion that “human factor” is one of the most important factors limiting the precision of the measurements, but almost never took into account in uncertainty budged.

6. Summary

In the paper short review of the measurement methods and main factors that limit accuracy of the near-field EMF metrology are presented. Except technical factors we have to take into an uncertainty budget a „human factor”. If we consider all factors degrading the accuracy of measurements, one can say that survey measurements uncertainty better than ± 2-4 dB is a satisfying result. As a proof of this thesis the final results of ILC/PT program in EMF survey measurements are presented in Figure 10.

-80

-60-40

-200

20

4060

80

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Measurement in point number

E/E

mea

n [%

]

Figure 10. Finally results of ILC/PT program

Acknowledgment

The research was partly supported by Polish Ministry of Science and Higher Education (Grant: 3T11D00629)

References

[1] H. Trzaska, Electromagnetic Field Measurements in the Near Field, Noble Publ. Corp. 2001. [2] P. Bienkowski, H. Trzaska, Frequency limitations in photonic EMF probes, Electromagnetic

compatibility 1997. 12th International Zurich Symposium and Technical Exhibition on Electromagnetic Compatibility, Zurich 1997, pp. 603-606.

[3] P. Bienkowski, Parameters of wideband electromagnetic field sensors and possibilities of their modification, Applied Electronics 2005. International conference. Pilsen, 2005 pp. 41-44.

[4] P. Bienkowski, Accuracy limitation factors in near field EMF metrology. COST 281/EMF-NET Seminar on the Role of Dosimetry in High-Quality EMF Risk Assessment; Zagreb, Croatia 2006.

[5] P. Bienkowski, H. Trzaska, Interlaboratory comparisons in EMF survey measurement - methods and results, International Conference and COST 281 Workshop on Emerging EMF Technologies, Potential Sensitive Groups and Health, COST Action 281, Graz, Austria, April, 2006.


Cardio-Vascular Homeostasis and Changes in Geomagnetic Field,

Estimated by Dst-index S. DIMITROVA1

Solar-Terrestrial Influences Laboratory at the Bulgarian Academy of Sciences

Abstract. Physiological parameters of 86 healthy volunteers were examined. 26 of them were taking medicaments mainly because of hypertension. The examinations were performed every working day at one and the same time for each person during the autumn and spring equinox in years of maximal solar activity. MANOVA was employed and the influence of the factors geomagnetic activity, estimated by Dst-index, gender and taking/not taking medicaments was investigated. The results obtained revealed that arterial blood pressure and pulse pressure increased statistically significantly with geomagnetic activity increment. It was found that probably physiological parameters of females and persons on medications were more sensitive to geomagnetic activity increase.

Keywords. Geomagnetic activity, arterial blood pressure, pulse pressure, heart rate

1. Introduction

All living organisms including human beings are continuously exposed to natural electromagnetic fields (EMF). Biological systems have accommodated to these fluctuations in the course of evolution but they have never stopped reacting to any sharp changes in environmental physical conditions.

The possible influence of helio-geophysical factors on biological processes has a great importance for medicine and social-economic life [1, 2, 3, 4, 5]. Different indices are used for assessment of geomagnetic activity (GMA) related to solar variations. During the last years we have studied the influence of changes in GMA by using different indices (Ap, Kp-indices and amplitude of H-component of local geomagnetic field on human physiological and psycho-physiological parameters [6, 7, 8]. Here we present results obtained from investigations of effect of changes in GMA, estimated by hourly Dst-index on arterial blood pressure (ABP), pulse pressure (PP) and heart rate (HR).

Dst (Disturbance Storm Time) is a geomagnetic index, which monitors the worldwide magnetic storm level. It is constructed by averaging the horizontal component of geomagnetic field (GMF) from mid-latitude and equatorial magnetograms from all over the world. Negative Dst values indicate a magnetic storm is in a progress. The more negative Dst is, the more intense the magnetic storm.

1 Svetla Dimitrova: Solar-Terrestrial Influences Laboratory at the Bulgarian Academy of Sciences, Acad. G.

Bonchev Str. Bl. 3 Sofia 1113, Bulgaria; Email: [email protected]



238

Our examinations were performed in Sofia city, which is situated at middle latitudes (Latitude: 42°43' North; Longitude: 23°20' East). Therefore Dst is a very appropriate index for such investigations. Moreover Dst is an hourly index and our measurements were performed at one and the same time for each person during the day which allows to assess the effect of current GMA on the physiological state of the persons examined.


Data were obtained in 86 volunteers (33 males and 53 females) of an average age 47.8 years. 26 persons in the group had cardio-vascular complaints (mainly hypertension) and were taking medicaments, prescribed by physicians. Recording of physiological parameters was performed on every working day from 1 October 2001 to 9 November 2001 and from 8 April 2002 to 28 May 2002. These periods were chosen because of the high probability for geo-effective solar storms during the autumn and spring. Observation periods were in years of maximal solar activity.

Systolic blood pressure (SBP), diastolic blood pressure (DBP) and HR were measured. PP is the algebraic difference between SBP and DBP and it was computed. ABP was registered by sphygmomanometric method to the single millimetre of Hg because of the required accuracy for such investigations. HR was palpatorically measured over arteria radialis as beats/minute and by counting for a full minute. A total of 2799 measurements for each of the physiological parameters examined were gathered.

The impact of the following factors on the physiological parameters under consideration was studied: “GMA, estimated by hourly Dst-index”, “medication - taking/not taking medication”, and “gender – males/females”.

GMA was divided into 5 levels according to Dst-index values (Table 1). Data were got from Internet (World Data Center for Geomagnetism, Kyoto: http://swdcdb.kugi.kyoto-u.ac.jp/). The number of measurements for each of the physiological parameters for the corresponding GMA levels, which were realized during our examinations, is also presented in Table 1.

Table 1. Dst-index levels.

GMA level 1st level (quiet GMA)

2nd level (weak storm)

3rd level (moderate storm)

4th level (major storm)

5th level (severe storm)

Dst, nT Dst > -20 -50 < Dst ≤ -20 -100 < Dst ≤ -50 -150 < Dst ≤ -100 Dst ≤ -150

Number Measurements

1819 544 290 104 42

Above-discussed factors were used to apply 3-Factor Analysis of Variance (MANOVA). The main effect and the interaction effect between the factors under consideration on the physiological parameters examined were investigated.

Post-hoc analysis (Neman-Keuls test) was also used to establish the statistical significance of the differences between the average values of the measured physiological parameters in the separate factor levels. The chosen level for statistical significance was p<0.05.

S. Dimitrova / Cardio-Vascular Homeostasis and Changes in GMF, Estimated by Dst-Index 239

3. Results

Table 2 shows significance levels p of main effect and interaction effect for the factors investigated on the physiological parameters examined. Table 2. MANOVA table for significance levels of main effect and interaction effect for the factors investigated (GMA, estimated by Dst-index; Gender; and Medication) on the physiological parameters examined.

Effect (main and interaction effect for the factors)

p

SBP DBP PP HR

GMA 0.000* 0.000* 0.002* 0.588

Gender 0.000* 0.003* 0.003* 0.010*

Medication 0.000* 0.000* 0.000* 0.000*

Gender * Medication 0.865 0.113 0.107 0.378

GMA * Gender 0.062 0.076 0.467 0.844

GMA * Medication 0.526 0.939 0.155 0.455

GMA * Gender * Medication 0.88 0.684 0.69 0.347

* - statistically significant effect

Main effect for the factor GMA, estimated by Dst-index, revealed that GMA influenced statistically significantly on SBP, DBP and PP (Table 2) of the group examined. The average value of ABP of the group increased with the decrease of Dst-index values (Figure 1). Post hoc analyses showed that ABP reached statistically significant increment during moderate storms. The maximal growth for SBP of the group was 11.2% and for DBP 10.1%. Vertical bars in the figure denote 0.95 confidence intervals (CI).

PP of the group also increased and it was significantly higher at severe geomagnetic storms in comparison with the other GMA levels and the range of changes was 13.4% (Figure 2).

HR of the group was not significantly changed (Table 1). The maximal increase of that physiological parameter for the group was only 1.4% (Figure 2).

Two-way interaction effect for factors GMA and gender revealed a trend SBP and DBP of males and females to react in a different way at GMA increment (p<0.1, Table 2). Figure 3 shows dynamic of ABP for both genders under GMA variations. It was established that SBP and DBP for females increased respectively with 13.7% and 11% from 1st to 5th GMA level while for males the corresponding values were 8.9% and 9.1%.

PP dynamic for males and females under different GMA conditions is shown on Figure 4. The increment of PP for females was 19.4% while for males only 8.5%.

Post-hoc analyses revealed that females were probably more sensitive at GMA increase than males. Females’ ABP reacted statistically significantly still at moderate storms and PP at severe storms. At the same time males’ ABP reacted significantly hardly at severe storms and their PP was not changed significantly when Dst-index values decreased. Significant differences in HR reaction of males and females examined to Dst-index changes were not revealed, Figure 4.

S. Dimitrova / Cardio-Vascular Homeostasis and Changes in GMF, Estimated by Dst-Index240

Two-way interaction effect for factors GMA and medication on physiological parameters examined was not statistically significant (Table 2). Although, it was established by the additional Post hoc analyses that persons on a medication were probably more sensitive to Dst-index changes than persons not taking medicaments since their SBP reaction during severe storms was more sharply expressed, DBP reacted statistically significantly still at major storms (Figure 5) and only they increased significantly PP during severe storms (Figure 6). Significant changes in HR for both subgroups were not established (Figure 6). HR variations were only 4% for persons not taking medicaments and 4.6% for persons taking medicaments. The maximal increase for SBP, DBP and PP for persons taking medicaments was respectively: 13.6%, 9.8% and 21.5% and for persons not taking medicaments: 8.5%, 10.3% and 4.5%.

Post hoc analyses for three-factor interactions confirmed the probable higher sensitivity of the persons taking medicaments and females in comparison with respectively persons not taking medicaments and males.

Syst(L) Diast(R)

1 2 3 4 5GMA levels

110

115

120

125

130

135

140

Syst

olic

BP,

mm

Hg

80

85

90

95

100

105

Dia

stol

ic B

P, m

mH

g

Figure 1. Main effect for GMA on SBP and DBP (±95% CI)

PP(L) HR(R)

1 2 3 4 5GMA levels

38

40

42

44

46

48

50

Puls

e pr

essu

re, m

mH

g

6062646668707274767880

Hea

rt ra

te, b

eats

/min

Figure 2. Main effect for GMA on PP and HR (±95% CI)

SBP Males (L) SBP Females (L) DBP Males (R) DBP Females (R)

1 2 3 4 5GMA levels

100105110115120125130135140145

Syst

olic

BP,

mm

Hg

75

80

85

90

95

100

105

110

Dia

stol

ic B

P, m

mH

g

Figure 3. Two-way interaction effect for factors GMA and Gender on SBP and DBP (±95% CI); (L) denotes Left axis while (R) – Right axis

PP Males (L) PP Females (L) HR Males (R) HR Females (R)

1 2 3 4 5GMA levels

36

39

42

45

48

51

54

Puls

e pr

essu

re, m

mH

g

56

60

64

68

72

76

80

Hea

rt ra

te, b

eats

/min

Figure 4. Two-way interaction effect for factors GMA and Gender on PP and HR (±95% CI); (L) denotes Left axis while (R) – Right axis


SBP No Medic (L) SBP Medic (L)DBP No Medic (R) DBP Medic (R)

1 2 3 4 5

GMA levels

100

110

120

130

140

150

Syst

olic

BP,

mm

Hg

80

90

100

110

120

Dia

stol

ic B

P, m

mH

g

Figure 5. Two-way interaction effect for factors GMA and Medication on SBP and DBP (±95% CI); (L) denotes Left axis while (R) – Right axis

PP No Medic (L) PP Medic (L)HR No Medic (R) HR Medic (R)

1 2 3 4 5

GMA levels

35

40

45

50

55

60

65

Puls

e pr

essu

re, m

mH

g

45

50

55

60

65

70

75

80

Hea

rt ra

te, b

eats

/min

Figure 6. Two-way interaction effect for factors GMA and Medication on PP and HR (±95% CI); (L) denotes Left axis while (R) – Right axis

4. Conclusions and Discussion

Our examinations and analyses revealed changes in some physiological parameters in result of GMF disturbances. ABP of the group examined increased with the decrease of Dst-index values. The fact that the increment of SBP and DBP reached 10-11% deserves attention from a medical point of view. Moreover PP of the group also increased, especially during severe geomagnetic storms when the increment reached 13.4%.

Analyses showed that probably physiological parameters of females and persons taking medicaments were more sensitive than respectively males and persons not taking medicaments to GMA increase.

It was expected that persons with anti-hypertension therapy would have been much more sensitive to GMA but possibly owing to pharmaceutical precautions their reaction was not statistically significantly different from the reaction of healthy persons. However we should pay attention that they had sharper reaction of SBP during severe geomagnetic storms as well as that they increased very strongly PP.

Results obtained enhance the importance of other similar investigations which were retrospective – analyzing of average values of ABP and HR of persons for a period of several years or of different group persons [9, 10]. Variations obtained in these and our investigation are very close – the difference between the most disturbed and quiet days in respect to GMF was about 6-8 mmHg.

Results obtained show that investigations in that field should continue and more data should be gathered, especially if it is possible at different geographical regions and latitudes. If future similar studies confirm the results presented it could be helpful for countermeasures to protect people from adverse solar emissions, especially unstable individuals and persons with different pathology.

S. Dimitrova / Cardio-Vascular Homeostasis and Changes in GMF, Estimated by Dst-Index242

Acknowledgment

This study was partially supported by National Science Fund of Bulgaria under contract NIP L-1530/05. We thankfully acknowledge the contribution of all volunteers who took part in the examinations.

References

[1] G. Cornelissen, F. Halberg, T. Breus, E. Syutkina, R. Baevsky, A. Weydahl, Y. Watanabe, K. Otsuka, J. Siegelova, B. Fiser, E. Bakken, Non-photic solar associations of heart rate variability and myocardial infarction, JASTP 64 (2002), 707-720.

[2] М. Zhadin, Review of Russian literature on biological action of DC and low-frequency AC magnetic fields, Bioelectromagnetics 22 (2001), 27-45.

[3] F. T. Hong, Magnetic field effects on biomolecules, cells, and living organisms, Biosystems 36 (1995), 187-229.

[4] S. J. Palmer, M.J. Rycroft, M. Cermack, Solar and geomagnetic activity, extremely low frequency magnetic and electric fields and human health at the Earth’s surface, Surveys in Geophysics 27 (2006), 557–595.

[5] E. S. Babayev, A.A. Allahverdiyeva, Effects of geomagnetic activity variations on the physiological and psychological state of functionally healthy humans: some results of Azerbaijani studies. Advances in Space Research 40 (2007), 1941-1951.

[6] S. Dimitrova, I. Stoilova, I. Cholakov, Influence of local geomagnetic storms on arterial blood pressure, Bioelectromagnetics 25 (2004), 408-414.

[7] S. Dimitrova, I. Stoilova, T. Yanev, I. Cholakov, Effect of local and global geomagnetic activity on human cardiovascular homeostasis, Int. J. Archives of Environmental Health 59 (2004), 84-90.

[8] S. Dimitrova, Relationship between human physiological parameters and geomagnetic variations of solar origin, Advances in Space Research 37 (2006), 1251-1257.

[9] E. Stoupel, C. Wittenberg, J. Zabludowski, G. Boner, Ambulatory blood pressure monitoring in patients with hypertension on days of high and low geomagnetic activity, J. Hum. Hypertens. 9 (1995), 293-294.

[10] S. Ghione, L. Mezzasalma, C. Del Seppia, F. Papi, Do geomagnetic disturbances of solar origin affect arterial blood pressure?, J. Hum. Hypertens. 12 (1998), 749-754.


Progress in the ITU Work Concerning Protection Against Radiation

Fryderyk LEWICKI1

Telekomunikacja Polska R&D, Poland, Abstract. Human exposure to electromagnetic fields (EMFs) is a matter of considerable public concern and therefore many international standardization bodies are involved in this problem. In this paper the activity of the International Telecommunication Union (ITU) is described. It deals with the exposure assessment around the operating transmitting stations in multiple sources environment and with modeling of the transmitting antennas based on telecommunication operators experience. Recommendations prepared by the ITU are presented. It is pointed out that the work carried out by ITU is complementary to the activity of other entities.

Keywords. Human exposure, cumulative exposure, multiple sources environment

Introduction

Over the last two decades a significant progress can be noticed in the development of radiocommunication services, which leads to the substantial growth in the transmitting equipment in use and to the considerable increase in the number of transmitting and base stations. In this paper the International Telecommunication Union (ITU) activity in the field of the exposure assessment in the areas around operating radiocommunication installations is presented. ITU is the United Nations agency for information and communication technologies. It is divided into 3 sectors: radiocommunication, standardization and development. ITU is based in Geneva, Switzerland, and its membership includes 191 Member States and more than 700 Sector Members and Associates.

1. Protection Against Radiation – ITU Activity

ITU activity in the standardization consists mainly in preparing Recommendations that are used worldwide and refer to telecommunication installations. Electromagnetic fields in the areas around radiocommunication installations are under consideration of the ITU-T Study Group 5 (SG5) and ITU-R SG6. ITU defines, for an internal use, its own field of activity in order to prevent duplication of the work carried out in other international standardization bodies like WHO, ICNIRP, IEEE, IEC TC 106 or CENELEC TC 106X. ITU activity is focused on guiding telecommunication operators how to handle the problem of protection against radiation in the areas around existing

1 Corresponding Autor: Fryderyk Lewicki, Telekomunikacja Polska R&D, ul. Prusa 9, 50-319 Wrocław 48, P.O. Box 2454, , Poland; E-mail: [email protected]



244

transmitting stations in the situation of simultaneous exposure to multiple sources used for different radiocommunication services (operating in different frequency ranges and belonging to numerous operators). The ITU goal is to give guidance to all the interested entities on how to apply standards and limits to the existing telecommunication installations and how to model the operating transmitting antennas.

ITU-T SG5 “Protection against electromagnetic environment effects” includes Question 3/5 “Radio-frequency environmental characterization and health effects related to mobile equipment and radio systems” dealing with this subject. Currently there are three ITU-T Recommendations in force.

ITU-T Recommendation K.52 “Guidance on complying with limits for human exposure to electromagnetic fields” [1] defines classes depending on the category of: transmitting antenna directivity, accessibility to people and general public or occupational exposure. For each class it gives a simple equation allowing for compliance evaluation.

ITU-T Recommendation K.61 “Guidance to measurement and numerical prediction of electromagnetic fields for compliance with human exposure limits for telecommunication installation” [2] provides an overview of the measurements and numerical prediction of ELFs for compliance with human exposure limits.

ITU-T Recommendation K.70 “Mitigation techniques to limit human exposure to EMFs in the vicinity of radiocommunication stations” [3]. This Recommendation gives guidance for mitigation techniques which may be used in order to decrease radiation levels in the areas around typical transmitting or base stations which are accessible to people. It includes the guidance on how to identify the main source of radiation (the source which gives the highest levels of radiation) and moreover the guidance concerning required modifications of the transmitting antennas configuration in order to decrease radiation levels. This Recommendation contains descriptions of typical radiocommunication antennas (broadcasting, mobile and other), including radiation patterns and typical ERP levels used for different services. These parameters may be used if exact data concerning transmitting antennas are not accessible, in order to give an estimation of the level of radiation which may be expected. Such general information may be sufficient if radiation level is substantially under the limits.

ITU-T Rec. K.70 contains, as the Appendix, the software EMF-Estimator, that was designed to support the application of mitigation techniques, but any other software appropriate for numerical modeling may be also used. The EMF-estimator allows for the calculations of the field in the far-field region (exact results) and in the radiating near-field region (results with satisfactory exactness). It is designed especially for the multiple sources environment which is now a typical situation. Fig. 1 presents an example of the screen output on which the results of calculations of the cumulative exposure as a function of distance to the antenna tower are drawn. In this case 5 operating frequencies are under consideration. The EMF-Estimator includes library with typical radiocommunication antennas and gives the possibility to introduce the user defined antennas for the exposure assessment.

F. Lewicki / Progress in the ITU Work Concerning Protection Against Radiation 245

Figure1. Example of the screen of the EMF-estimator – results of calculations of the Cumulative Exposure

ITU-R SG6 “Broadcasting Services” in the Working Party 6E (WP6E) “Terrestrial delivery” has prepared the Recommendation BS.1698 “Evaluating fields from terrestrial broadcasting transmitting systems operating in any frequency band for assessing exposure to non ionizing radiation” [4]. This Recommendation provides guidance concerning an influence of the type of modulation used in telecommunication for the radiation levels and guidance for numerical prediction and measurements in the vicinity of telecommunication installations, mainly for MF and HR broadcasting and for parabolic antennas.

2. Importance of the Transmitting Antenna Modeling

In the exposure assessment, a very important issue is the accuracy of the computer simulations of electromagnetic fields (EMFs). This accuracy depends on the tools used in computational electromagnetics, on the models of the environment (including, for example, human tissues) and of transmitting antennas. As far as the first two points are concerned many satisfactory methods and models are proposed as standards. A different situation occurs in the field of transmitting antenna modeling. The transmitting antennas are usually described in a very simplified way or represented just by a dipole (prEN 50492), while real telecommunication antennas are usually very

F. Lewicki / Progress in the ITU Work Concerning Protection Against Radiation246

complex, for example up to 256 dipoles with screens operating as one transmitting antenna.

A transmitting antenna determines the distribution of energy around transmitting stations and if a numerical model is not accurate enough, then the evaluation is not satisfactory [5, 6]. In general, it is very difficult (in some cases even impossible) to obtain exact data describing transmitting antennas on operating frequency. In manufacturers catalogues only general information, such as antenna gain and radiation patterns for central frequency, can be found. There are amplitude radiation patterns only (without any phase information) and in most cases in polar coordinates, which make them very difficult to read and use (vertical radiation patterns for many transmitting antennas are very narrow and with many sidelobes). A transmitting antenna may be precisely modeled, using full wave numerical modeling for example using the method of moments (MoM), but it requires even more exact data covering detailed antenna geometry and full information concerning antenna feeding arrangement. A transmitting antenna feeding arrangement is very difficult to obtain because it is know-how of the manufacturer. It determines the antenna electric and propagation parameters and such knowledge may be used by competing manufacturers. The exact data for modeling transmitting antennas is especially required if:

• the radiation levels are near or exceed the exposure limits • the transmitting antennas are of high gain type. In all cases the accuracy of the transmitting antenna modeling determines the

accuracy of the exposure assessment. It is a very good practice to approve all evaluations by measurements but it should be noted that the measurement has also limited accuracy and should be done properly.

3. Experiences of the Telecommunication Operators

Since in many countries the radiation limits are very restrictive (much more conservative than ICNIRP limits), the telecommunication operators have considerable experience in decreasing the radiation levels, because radiation can cause serious problems when it exceeds the exposure limits, especially for general public. It has been found that the most effective way is to make proper changes in the feeding arrangement which allows to modify a transmitting antenna vertical radiation pattern [5, 6]. This solution is cost effective (does not require any changes in antenna geometry) and it makes possible to sustain propagation parameters, i.e. with no changes in the coverage area, which is very important for telecommunication operators.

An example of the application of the mitigation techniques is shown in fig. 2. On the left the result of calculations of the cumulative exposure for the transmitting station with 6 FM high power, 2 TV high power and many radiocommunication (including GSM) operating frequencies is shown. It can be seen in the figure that there is a big area where exposure limits are exceeded (cumulative exposure higher than 1). After the modification of the FM transmitting antenna (using the methods described in the ITU-T Recommendation K.70) the cumulative exposure distribution has changed as it is shown in fig. 2 (on the right). It can be seen that the radiation levels around the transmitting station have been reduced substantially and now they are under the limits. The compliance with exposure limits has been achieved by the modification of the FM transmitting antenna configuration (changes in antenna geometry and in tnatenna feeding arrangement).

F. Lewicki / Progress in the ITU Work Concerning Protection Against Radiation 247

Figure 2. Example of the application of mitigation techniques. Cumulative exposure around the transmitting station, before (left) and after (right) changes in the FM antenna configuration

4. Conclusion

In this paper the ITU activity in the field of protection against radiation is described. It has been pointed out that the ITU-T activity is complementary to the activity of other international standardization entities. In order to improve the dialogue between various organizations active within the EMF Health Effects domain, to increase the understanding and alignment, and to reduce the potential duplication of standardization efforts, the ITU-T is organizing the Workshop: “Human exposure to electromagnetic fields (EMFs)”, in Geneva, November 2007. An example of evaluation of the EMFs which show the importance of modeling the transmitting antennas and the effectiveness of mitigation techniques leading to the reduction of radiation levels have also been presented.

References

[1] ITU-T Recommendation K.52, Guidance on complying with limits for human exposure to electromagnetic fields, Geneva 2004.

[2] ITU-T Recommendation K.61, Guidance to measurement and numerical prediction of electromagnetic fields for compliance with human exposure limits for telecommunication installations, Geneva 2003.

[3] ITU-T Recommendation K.70, Mitigation techniques to limit human exposure to EMFs in the vicinity of radiocommunication stations, Geneva 2007.

[4] ITU-R Recommendation BT.1698, Evaluating fields from terrestrial broadcasting transmitting systems operating in any frequency band for assessing exposure to non-ionizing radiation, Geneva, 2004.

[5] F. Lewicki, A. Ługowski, S.A. Lesiak, Simplification of the Exposure Assessment in Multiple Sources Environment, XVIII International Wroclaw Symposium on EMC, Wroclaw, Poland, pp 123-126, 2006.

[6] F. Lewicki, Importance of Antenna VRP in Radiation Protection Consideration, XVII International Wroclaw Symposium on EMC, Wroclaw, Poland, pp 80-84, 2004.

F. Lewicki / Progress in the ITU Work Concerning Protection Against Radiation248

A Verification of Quality and Efficiency of Therapeutical System Using

Electromagnetic Field Mira LISIECKA-BIEŁANOWICZ1, Andrzej KRAWCZYK2, Adam LUSAWA1

1Department of Prevention of Environmental Hazards, Medical Academy of Warsaw, Poland, [email protected]

2Central Institute for Labour Protection – National Research Institute, Warsaw, Poland, [email protected]

Abstract: The paper deals with the evaluation of therapeutic systems which use electromagnetic field of low frequency. The key-point of the research is to evaluate and verify the real effectiveness of such therapies, taking into account the fact that majority of them are scientifically unproved.

Introduction

The paper deals with the evaluation of therapeutic systems which use electromagnetic field of low frequency. The key-point of the research is to evaluate and verify the real effectiveness of such therapies, taking into account the fact that majority of them are scientifically unproved.

The aim of this study is to make a verification of interaction between three components: patient, therapist and environment. All three members take part in the process of medical benefits (service). In this process electromagnetic field is generated. It has some physical (technical) parameters and also some parameters which can be described as “added value” for patients. This “special mix” of therapeutic fields creates a quality of relation and one can nearly feel as “being in tough” as a patient or as a therapist. Qualification of the relation process - how the patient takes it - depends on his wishes and his experiences.

Quality of the Process

During a therapeutic process people are involved in creating a good atmosphere for medical services. It is very important to put a perception of quality service into partnership’s perspective with reference to qualification and resource services, but based on a patient expectation and earlier experiences[1]. The quality service is based on verification facts and can be classified as follows[2]:

1. quality in perception (Qp); this is a quality which is expected and imagined compared with a quality which is experienced and confirmed by client in a whole cycle of servis,.


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2. quality in facts and norms (QF); into this part of quality we put everything what we can define precisely or measure or what we can put into norms and standards.

3. quality in relations (QR); in this part of quality we put attention into long term of relation with a patient during the whole medical process (thought diagnosis, medical treatment and therapy).

During medical process the time of quality in relations (QR) cannot be reduced only into a strict time of medical visit or into a results of examination but should persist and create as a model of interaction.

Referring the above considerations to electromagnetic therapies one can say that these therapies are weak of theoretical fundaments but base on an experience of therapies and quality of the facilities used in the process. It evokes sui generis interaction between patient, therapist and environment. The latter one is just electromagnetic field described by a set of parameters as well as the devices which generate electromagnetic field which, in turn, builds therapeutic effect. The model of interactions, presented in the paper, giving quantitatively three qualities, can be successfully used in planning the therapeutic process and improve its efficiency. To this end one needs to have technical, sociological and psychological parameters.

Method and Material

The procedure for verification (either confirmed or falsified) therapeutic processes using electromagnetic field covers the following steps:

1. the examination of electromagnetic field as to its parameters – frequency, amplitude, shape of impulse and time of its duration, distribution of the quantity which describes electromagnetic field in the area of therapy,

2. filling in the examination sheet by the patient , 3. analysis of the collected sheets and correlating them with technical

parameters gathered in step 1. The first step is of technical nature and, therefore, relatively easy to be done. Also, some technical information comes from a producer of each particular device.

The method of statistical examination used Statistica 7.1 and Pearson correlation with the assumption that correlations are significant at the 0,01 level. The personal data is shown in Tables 1, 2 and 3:

Table 1. Sex

N % Female 74 72,5 Male 28 27,5

Table 2. Age

Avarge Female 56,5 Male 53,3 All 55,9

M. Lisiecka-Biełanowicz et al. / A Verification of Quality and Efficiency of Therapeutical System250

Table 3. Education

N % basic 1 1,0 basic professional 4 3,9 high school 17 16,7 technical high school 18 17,6 university (humanistic) 26 25,5 technical university 12 11,8 economical university 24 23,5

Results

The most significant correlations are presented in Figures 1-8

Figure 1. Correlation between therapist’s treatment and patient’s opinion about their relations (k=0,86).

Figure 2. Correlation between knowledge before and after therapy (k=0,60).

M. Lisiecka-Biełanowicz et al. / A Verification of Quality and Efficiency of Therapeutical System 251

Figure 3. Correlation between opinion about efficiency and knowledge after therapy (k=0,54).

Figure 4. Correlation between daily activity before and after therapy (k=0,49).

Figure 5. Correlation between health and daily activity before therapy (k=0,68).


Figure 6. Correlation between health and daily activity after therapy (k=0,68).

Figure 7. Correlation between health and well-being before therapy (k=0,44).

Figure 8. Correlation between health and well-being after therapy (k=0,70).

M. Lisiecka-Biełanowicz et al. / A Verification of Quality and Efficiency of Therapeutical System 253

Discussion and Conclusions

The results of the study, presented above, create the stage for the discussion about: 1. the connection between patient’s health and patient’s daily activity, 2. the connection between therapist’s treatment and good patient’s contact with

therapist, 3. the connection between health and well-being or well-being and health, but

after therapy influence of therapy increase correlation between health and well-being.

The results are not surprising and show the intuitively expected tendencies. For example, the biggest correlation is for examination of therapist’s treatment vs. opinion about therapy. But such a result confirms the credibility of patients’ answers. Then, we may be sure that other answers are also credible.

There is relatively big correlation factor, which shows the relation between knowledge after therapy vs. knowledge before therapy. It means that the therapy do not change the patients’ knowledge. In consequence, the value of correlation factor showing the relation between efficiency and knowledge after therapy (0,54) indicates that there is no connection between patients’ knowledge neither before nor after therapy and its efficiency. This can be concluded that efficiency of therapy does not depend on how many information about therapy a patient knows.

The relations between health and well-being measured both before and after therapy show that therapeutic process is positive since it links health and well-being to some extent. The summarising conclusion may be formulated as follows:

therapy in electromagnetic field has not a big influence on patients’ health but has influence on their well-being in most cases.

The research is still in its infant stadium and we need more analyses to verify electromagnetic therapies which is the final aim of the study.

References

[1] Rudawska I., Jakość relacji pacjent – profesjonalista w sektorze usług medycznych. W: Problemy Jakości nr 3/2005, Wydawnictwo SIGMA-NOT, Warszawa, 2005 r., str. 12 – 15.

[2] Rogoziński K., Jakość usług w horyzoncie aksjologicznym. w: Problemy Jakości nr 1/2005, Wydawnictwo SIGMA-NOT, Warszawa, 2005 r., str. 24 oraz 29-32.

[3] Stanisz A., Biostatystyka, Wydawnictwo Uniwersytetu Jagiellońskiego, Kraków, 2005.


Implantable Cardioverter Defibrillator and UMTS Telephones Interaction

Anna PLAWIAK-MOWNA1, Andrzej KRAWCZYK2

1University of Zielona Gora, Institute of Computer Engineering and Electronics, Zielona Gora, Poland, 2 Central Institute for Labour Protection – National Research

Institute, Warszawa, Poland

Abstract. The paper presents problems of implantable cardioverter defibrillator exposed to electromagnetic field. The authors have focused on EMF source – UMTS mobile phone antenna and base station antenna. The authors made experiments with exposure cardiac implants to electromagnetic field from GSM mobile phone and base station antenna. In the paper is described the problem of ICD interaction with 3G mobile phones antenna and the results of numerical calculation.

Keywords. Electromagnetic interaction, electromagnetic fields, electro-medical device, calculation

Introduction

The ICD wearers can safely operate most household and office equipment, provided this person takes a few precautions. Several safeguards built into defibrillator protect it from interference encountered in normal daily living. Such safeguards include electronic filters that separate natural heartbeat signals and interference signals. Implantable cardioverter defibrillators are qualified to life-support medical electrical implants. Manufacturers design medical devices to be immune to electromagnetic fields up to 10 V/m for life-support medical electrical equipment, as proposed in international standards. Meeting these standards would reduce the potential hazards of EMI [9]. Specific EMC standards for implantable cardiac pacemakers and defibrillators are currently being drafted by ISO. Electromagnetic field at environment comes mainly from public available sources, like the home appliances, power lines or base station antenna which occur near places where people live or mobile phones and other wireless communication devices. Some of them are easy to avoid their influence, other are difficult to be avoided. The progress of wireless mobile communication technology has generated awareness about electromagnetic interferences of cardiac implants with cellular phones and base station antenna.

The work discusses threats connected with possibility to appear interference of external electromagnetic fields from UMTS mobile phone with the function of an implantable cardioverter defibrillator. _________________________

1Anna Plawiak-Mowna: Institute of Computer Engineering and Electronics, University of Zielona Gora, Podgorna 50, 65-246 Zielona Gora, Poland; E-mail: [email protected]

2 Andrzej Krawczyk: Central Instutute of Labour Protection – National Research Institute, Czerniakowska 16, 00-701 Warszawa, Poland. E-mail: [email protected]


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1. An ICD at Electromagnetic Field

Implantable cardioverter defibrillators (ICDs) are small devices, about the size of a pager, that are placed below the collarbone. Via wires, or leads, these devices monitor the heart’s rhythm and delivers energy used for pacing, cardioversion and/or defibrillation. An ICD senses local electrogram signals; detects sensed signals according to programmable heart rate zones; provides of therapy and paces for bradycardia and/or cardiac resynchronization therapy.

The ICD is designed to sense very low level biological signals, for that reason ICDs are highly sensitive low frequency receivers. The atrial sensitivity for electrical stimulation is 0.25-1.6 mV and ventricular is 0.75-4.0 mV. The sensitivity to external interference varies greatly between devices. A typical pulse generator senses in the range of 0 Hz to several hundred Hz. Minimum sensing threshold is dictated by electronic technology and battery capacity limitations. The sensitivity range for ICD is 0.15 - 2.1 mV. Necessary voltage and frequency for ICD implant sensing (sensing characteristic) is presented in Figure 1

Figure 1. An implantable cardioverter-defibrillator (ICD) sensing characteristic

The potential for interaction between implanted cardioverter-defibrillators and source of electromagnetic field has been recognized for ten years. It has been shown that EMI can produce significant effects on patients with implanted ICDs. Implantable cardiac implants may be sensitive to electromagnetic fields generated by personal items (GSM mobile phone [2,3,10,14,15,18,21,22]), industrial equipment [4,11,12,20], medical device (Magnetic Resonance Imaging scans [19]). The electromagnetic field may generate electrical potentials on ICD sensing electrodes then electromagnetic interference is results in improperly implants function. There are a number of possible ICDs and pacemakers responses to external interference:

1. temporary inhibition of the device (inhibition of pacing) or inappropriate delivery pacing and/or shocks (pacing/shock therapy not provided when needed) [2,4,5,21],

2. asynchronous acing [3,14], 3. inability to communicate with the device [10,15], 4. inappropriate shocks (shock therapy provided when not needed) [6], 5. deactivation of shock therapy [2], 6. trigger ventricular pacing at Maximum Tracking Rate [6].

A. Plawiak-Mowna and A. Krawczyk / Implantable Cardioverter Defibrillator256

2. Exam of Implantable Cardiac Implant Responses to External Interference

Examination of isolated ICD in phantom (in vitro in phantom) is performed with the implantable device submerged in a saline filled tank and with the source of radiated EMI in close proximity. This method of investigations allows study of interactions between various EMI sources and devices. Multiple iterations of the experiment permit examination of the effects of distance, position, field strength, and device programming on the frequency and severity of the interaction. Examination of isolated ICD (in vitro) - is performed similar to in vitro in phantom study. Device testing in vitro study is not submerged in a saline filled tank. Examination of ICD implanted in the human body - study with patient volunteers requires control patient exposure to potential sources of EMI. The fact that many sources of EMI might interfere complicates in vivo studies. The recorded electrocardiogram is the ideal method to evaluate device behavior during exposure to potential sources of EMI. Numerical simulation allows predict the possible hazards might occur in examination of pacemaker implanted in the human body; that method allows to quantify the relationship between an external electromagnetic field and the voltage induced in the leads of an implantable device.

3. An Implantable Cardiac Rhythm Device Examination at Electromagnetic Field from UMTS Mobile Phone

Third generation mobile phones (UMTS) will be introduced in common usage in the near future. The frequency band for this system is between 1800 and 2200 MHz and the power output between 0.01 W and 0.25 W. At present, the possibility to appear interference of external electromagnetic fields from UMTS mobile phone with the function of an implantable cardiac rhythm devices (cardiac pacemaker, implantable cardioverter defibrillator) is a subject of study for EMC specialists, cardiac implants and mobile phone manufacturers. Hekmat and colleagues [8] study comprised 22 single-chamber and 78 dual-chamber pacemaker patients. Two UMTS cellular phones were tested in the standby, dialing and operating mode with. All pacemakers were tested under a „worst-case scenario“, which includes a programming of the pacemaker to unipolar sensing and pacing modes and inducing of a maximum sensitivity setting during continuous pacing of the patient. Regardless of atrial and ventricular sensitivity settings all tested pacemakers did not show any interference with UMTS mobile phones. Gustrau and colleagues [7] presented numerical calculation for wireless telecommunication devices. The frequencies under investigation are 900 MHz, 1750 MHz, 1950 MHz for mobile phone use at head and chest (uplink) and 950 MHz, 1850 MHz and 2150 MHz for plane wave exposure (downlink). Scientists presented numerical calculations of the field-to-voltage transfer unction, i.e. the coupling between GSM and UMTS mobile phones and the base station antenna and the voltage induced the sensing input of cardiac pacemakers. For the numerical investigation they generated a CAD model of single chamber pacemaker with an unipolar electrode. The highest interference is voltage for UMTS mobile phone (67.5 mV) occurs when the mobile phone is positioned in front of the chest at 5 cm distance from implant. In real-live situation (phone in head position) interference voltages are smaller, 0.825 mV for lest ear and 15.9 mV for right ear.

A. Plawiak-Mowna and A. Krawczyk / Implantable Cardioverter Defibrillator 257

Maximum interference voltage for plane wave exposure is 0.52 mV for vertical and horizontal polarization.

3.1. Results of Calculation

It was used a full 3D human model with 3 mm resolution from Brooks Air Force Laboratory, USA. It is based on anatomical slices from a male cadaver (1.8 m tall and 105 kg weight). The tissue parameters obtained from this model were used in the presented results of calculation [1]. For the numerical investigation a CAD model of pacemaker was generated. The size of the implantable pulse generator is 42x52x6 mm with unipolar electrode 560 mm in length. The projection area of the pacemaker configuration is 196 cm2, and “port1” is the housing port of pacemaker and “port2” is the end of electrode.In this paper the numerical model has to represent the UMTS mobile phone (2150 MHz). Using method of scaling [7], the distribution of electromagnetic field has been established for the case of plane wave.For the investigation of field-to-voltage function homogeneous electric and magnetic fields were used. In the case of the frontal magnetic field exposure (H=1 A/m) the interference voltage was calculated using Faraday’s law of induction. In the case of the frontal magnetic field exposure the interference voltage was 0.5 mV. In the case of vertical electric field exposure (E=1 V/m) the interference voltage at frequency 2150 MHz was U = 0.48 mV.

4. Summary

There are many factors that impact medical device EMC (EM source frequency, modulation and field strength). On the other hand medical implants are susceptible due to function (bandpass for sensing signals, lead system), telemetry function, environment and patients education. Results of calculation demonstrated that the interferences voltages are big enough not to be accepted for normal operation of implantable cardioverter defibrillator (Fig. 1). However, the case we considered is the worst as the projection area and the length of wire are extremely big. The method of numerical simulation gives pre-implanting prediction as to possible hazards. Our future plans will be focus on examination devices using in vitro method. The result of numerical calculations will be verified.

References

[1] Active Implantable Medical Devices, Electromagnetic Compatibility Test Protocols for Implantable Cardioverters', ANSJ/AAMI PC69:200, Association for the Advancement of Medical Instrumentation.

[2] V. Barbaro, P. Bartolini, F. Belloci, F. Caruso, A. Donato, D. Gabrielli, C. Militello, A.S. Montenero, P. Zecchi, Electromagnetic interference of digital and analog cellular telephones with implantable cardioverter defibrillators: In vitro and in vivo studies, Pacing and Clinical Electrophysiology, Vol. 22, pp. 626-634, 1999.

[3] V. Barbaro, P. Bartolini, A. Donato, C. Militello, Electromagnetic interference of analog cellular telephones with pacemakers, Pacing and Clinical Electrophysiology, Vol. 19, p. 1410, 1996.

[4] J.G. Fetter, D.G. Beneditt, M.S. Stanton, Electromagnetic interference from welding and motors on implantable cardioverter-defibrillators as tested in the electrically hostile work site, Journal of American College of Cardiology, Vol. 28 (2), pp. 423-427, 1996.

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[5] J. G. Fetter, V. Ivans, D.G. Benditt, J. Collins, Digital cellular telephone interaction with implantable cardioverter-defibrillators, Journal of American College of Cardiology, Vol. 31(3), pp. 623-628, 1998.

[6] Guidant Web Page, http:// www.guidant.com. [7] F. Gustrau, A. Bahr, S. Goltz, et al.: Active medical implants and occupational safety - measurement

and numerical calculation of interference voltage, Biomedizinische Technik. Biomedical engineering, Vol. 47 Suppl 1 Pt 2, pp. 656-659, 2002.

[8] K. Hekmat, R. Emini, R. Friedl, A. Hannekum, The interference of UMTS mobile phones with permanent implanted pacemakers, The Thoracic and Cardiovascular Surgeon, Vol. 55, Issue S 1, 2007.

[9] International Electrotechnical Commission, Medical Electrical Equipment, Part I: General Requirements for Safety, IEC Standard 601-1-2, 2001.

[10] F. Jimenez, A. Hernandez Madrit, J. Pascual, J.M. Gonzales Rebollo, E. Fernandez, A. Sanchez, J. Ortega, F. Lozano, R. Munoz, C. Moro, Electromagnetic interference between automatic defibrillators and digital and analog cellular telephones, Revista Espanola de Cardiologia, Vol. 51(51), pp. 375-382, 1998.

[11] C. Kolb, B. Zrenner, C. Schmitt, Incidence of electromagnetic interference in implantable cardioverter defibrillators, Pacing and Clinical Electrophysiology, Vol. 24, pp. 465-468, 2001.

[12] D. Marco, G. Eisinger, D.L. Hayes, Testing work environments for electromagnetic interference, Pacing and Clinical Electrophysiology, Vol. 15, pp. 2016-2022, 1992.

[13] Medtronic Web Page, www.medtronic.com. [14] B. Naegeli, S. Osswald, M. Deola, F. Burkart, Intermittent pacemaker dysfunction caused by digital

mobile telephones, Journal of American College Cardiology, Vol. 27, pp. 1471-1477, 1996. [15] E. Occhetta, L. Plebani, M. Bortnik, G. Sacchetti, C. Trevi, Implantable cardioverter defibrillators and

cellular phones: Is there any interference?, Pacing and Clinical Electrophysiology, Vol. 22, pp. 983-989, 1999.

[16] A. Pławiak-Mowna, A. Krawczyk, A. Miaskowski, Implantable cardiac rhythm device at workplace electromagnetic environment, Pomiary Automatyka Kontrola, Vol. 5, pp. 93-95, 2007.

[17] A. Pławiak-Mowna, A. Miaskowski, A. Krawczyk, J. Ishihara, Infulence of electromagnetic field on cardiac pacemakers at workplace, Pomiary Automatyka Kontrola, Vol. 6 (wyd. spec.), pp. 68-70, 2006.

[18] A. Pławiak-Mowna, T. Zyss , E. Koźluk, A. Krawczyk, R. Kubacki, Kardiostymulatory w polu elektromagnetycznym emitowanym przez telefony komórkowe, Telefonia komórkowa a ochrona zdrowia i środowiska : najnowsze przepisy i wyniki badań: fakty, Warszawa: Instytut Naukowo-Badawczy, 2003, pp. 27 – 37.

[19] A. Roguin , M.M. Zviman, G.R. Meininger, E.R. Rodrigues, T.M. Dickfeld, D.A. Bluemke, A. Lardo, R.D. Berger, H. Calkins, H.R. Halperin, Modern pacemaker and implantable cardioverter/defibrillator systems can be magnetic resonance imaging safe in vitro and in vivo assessment of safety and function at 1.5T, Circulation, Vol. 10, pp. 475-482, 2004

[20] A. Trigano, O. Blandeau, M. Souques, J.P. Gernez, I. Magne, Clinical study of interference with cardiac pacemakers by a magnetic field at power line frequencies, Journal of the American College of Cardiology, Vol. 45(6), pp. 896-900, 2005.

[21] J. Vlasinova, T. Novotny, Pacemaker dysfunction during use of a mobile telephone, Vnitr Lek, Vol. 46, pp.119-121, 2000.

[22] M. Yesil, S. Bayata, N. Postaci, C. Aydin, Pacemaker inhibition and asystole in a pacemaker dependent patient, Pacing and Clinical Electrophysiology, Vol. 18, p. 1963, 1995.

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Finishing the German Mobile Telecommunication Research Programme

(DMF)

Blanka POPHOF a,1, Monika ASMUSS a, Cornelia BALDERMANN a, Anne DEHOS a, Dirk GESCHWENTNER a, Michaela KREUZER a, Christiane PÖLZL a,

Gunde ZIEGELBERGER a and Rüdiger MATTHES a a Federal Office for Radiation Protection, Ingolstädter Landstrasse 1,

D-85764 Oberschleissheim, Germany

Abstract. The current state of the German Mobile Telecommunication Research Programme is introduced. The Programme was initiated by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety and is performed by the Federal Office for Radiation Protection. Concerning the possible health impact of HF-EMF, a total of 52 research projects are executed from 2002 to 2007 in four scientific fields: biology, dosimetry, epidemiology and risk communication. The total financial volume of the program is 17 Mio. €. Final results of the programme are expected in the middle of 2008.

Key Words. Mobile phone, health impact, research programmme, biology, dosimetry, epidemiology, risk communication

Introduction

High frequency electromagnetic fields such as those found, for example, near transmitters (e.g. radio and TV transmitters and mobile phone base stations) or when using mobile end devices (cell phones) are often suspected by the public of having adverse health effects on humans. There is some indication that such electromagnetic fields can cause biological or physiological effects at levels below international limit values. However, the question of whether or not they pose a health risk to the general public cannot be completely answered at this time.

The German Mobile Telecommunication Research Programme (DMF) was initiated by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) and the Federal Office for Radiation Protection (BfS) to clarify the above question. The total financial volume of the program is 17 Mio. €, equally shared by the BMU and the network operators. Coordination and implementation is carried out by the BfS. The research projects chosen for the program are based on the findings of two expert workshops in 2001 in Munich and in 2003 in Berlin and additional comments expressed by the general public. The first preliminary

1 Corresponding Author: Blanka Pophof, Federal Office for Radiation Protection, Ingolstädter Landstrasse 1, D-85764 Oberschleissheim, Germany, [email protected]



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results were presented in April 2005 at a public expert workshop. In the middle of 2008 final results of almost all projects are expected.

Detailed information on the single projects can be found on the DMF website http://www.emf-forschungsprogramm.de. Project descriptions, current results and workshop results are presented. Regular reports on the state of the research projects can be found on this web-site. The researcher's Final Report together with an evaluative statement by the BfS will be made available to the public at the end of every project. Further more general information on electromagnetic fields and cellular telecommunication can be found on the BfS website at http://www.bfs.de/elektro.

Research Projects

In the period from 2002 to 2007 a total of 52 research projects in mobile telecommunications are executed in four scientific fields: biology, dosimetry, epidemiology and risk communication. The topics cover a broad spectrum, reaching beyond current GSM and UMTS standards. One objective, among others, is to clarify fundamental effects and mechanisms. Another will be to delve into the possible causes of electromagnetic hypersensitivity. The programme will seek results pertinent not only to existing mobile telecommunications but in order to make statements on future developments as well.

Dosimetry

Fifteen projects, covering about 15 % of the total financial volume of the DMF, are concerned with dosimetry and exposure assessment; eleven of them are already finished, one will end in 2007 and three will proceed until the beginning of 2008. The topics cover on the one hand the field distribution around transmitters and far-field exposure of the population by mobile phone base stations, WLAN transmitters, transmitters for analogue and digital TV, etc. On the other hand, near-field scenarios are investigated predominantly by modeling the indoor field distribution in homes, offices, shielded rooms like trains or cars etc. Investigations of the real exposure due to daily use of mobile phones have shown, that GSM-mobile phones regulate quite often to the maximum transmission power, predominantly as a result of frequent handovers and poor signal quality, and cause therefore correspondingly high SAR-values in the head of the user. The different power control algorithms of UMTS-mobiles decrease the users´s exposure compared to GSM. SAR and temperature variations in the heads and trunks of persons using mobile communication devices were determined. The results show, that there is no overexposure of inner organs under realistic conditions. In order to provide dosimetric support to biological in-vivo experiments, the SAR distribution in laboratory animals was investigated as well.

Biology

The 22 projects investigating possible biological effects and health consequences of high frequency electromagnetic fields cover about 56 % of the financial volume of the DMF. Twelve projects are already completed, further five will be finished at the end of 2007, and five projects will continue till 2008. It could be shown, that a life-long exposure with GSM and UMTS signals does not influence the survival and the

B. Pophof et al. / Finishing the German Mobile Telecommunication Research Programme (DMF) 261

incidence of lymphoma in a mice stock especially susceptible to lymphoma (AKR-mice). The “melatonin hypothesis”, claiming that ELF as well as HF electromagnetic fields result in decreased melatonin levels, could not be confirmed during investigations on explanted pineal organs of hamsters. Electrophysiological experiments on single cells of the acoustic and visual system did not show any acute adverse effects of the GSM and UMTS signal. Concerning sleep quality, it could be shown that electromagnetic fields of mobile phones have no influence on various visually scored sleep parameters. Furthermore, shielding measures do not improve sleep quality of electrohypersensitive persons claiming to suffer from sleep disturbances resulting from electromagnetic fields of mobile phone base stations, if applied in a blinded design. Electrohypersensitive persons are a very heterogeneous group and cannot be described by a simple model. In transcranial magnetic stimulation they displayed a diminished ability to differentiate the sham from the magnetic pulse due to their high false alarm rate.

Epidemiology

Eight epidemiological projects are performed covering about 18% of the financial volume of the DMF. Five projects are finished, two more will be completed at the end of 2007, and one will continue until 2008. A pilot study has shown, that an occupational cohort study on persons highly exposed to HF EMFs is not feasible due to several methodological issues. In order to test whether Germany can participate in the planned international cohort study on mobile phone users (COSMOS), a pilot study was conducted. In principal the feasibility of such a study was successfully demonstrated. Yet, a major limitation was the low response rate of about 5% only. The effort necessary to recruit around 50.000 mobile phone users in Germany would be enormous and is not practicable within the DMF. The German part of the INTERPHONE study is finished, the results of the evaluation of the internationally pooled data are expected soon. Preliminary results from the single countries showed no increased risk for brain cancer due to a regular use of mobile phones for up to 10 years. Two epidemiological studies on children are still performed – a case-control study on childhood leukemia in relation to powerful radio and TV transmitters, and a cross-sectional study on acute health effects due to mobile telecommunication. In addition a cross-sectional study on adverse health effects in the vicinity of mobile phone base stations among adults has already been finished. Both cross-sectional studies used personal dosimeters to assess the exposure.

Risk Communication

All seven projects concerned with risk perception and some other social aspects of mobile communication, covering about 8 % of the financial volume of the DMF, are already finished. EMF-Portal - a new information system on scientific results regarding high and low frequency electromagnetic fields - is available online in German and English on the web site www.emf-portal.de. The results of an analysis of target groups show, that different population groups are differentially worried about possible health effects of electromagnetic fields. Five different target groups have been identified based on their concern about possible health effects of mobile phones and their use of mobile phones, as well as their specific information needs. The specific information needs and sociodemografic as well as psychological characteristics of

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electrohypersensitive persons were especially considered in a separate project. Annual surveys carried out since 2003 have shown, that the concern, the impairment, and the need for information remained constant over the years. About 9 % of the persons questioned claimed to have already experienced adverse health effects due to electromagnetic fields of mobile communications. Furthermore, based on the knowledge on public awareness and effects of information and communication activities recommendations were made how the design of information and communication activities could be optimized.

Conclusions

A large portion of the projects of the DMF is already finished or just being completed at the end of 2007. To provide a scientific discussion of all results of the DMF in the international context, single thematic topics were presented internationally in scientific workshops and discussed with national and international experts. The workshop with the topic “dosimetry” was performed in July 2006, the workshop with the topic “risk communication” in October 2006. The biological and epidemiological projects were combined in three workshops with the topics “Acute health effects” in December 2006, “Action mechanisms” in May 2007 and “Long-term effects” in October 2007. A final evaluation of the combined national and international research on the possible health effects of high frequency electromagnetic fields within and outside of DMF is planned in the form of an international scientific conference in June 2008. The results will form the base for risk assessment and communication.

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The Effect of MRET Polymer Compound

on SAR Values of RF Phones

Igor V. SMIRNOV

Global Quantech, Inc, U.S.A., [email protected]

Abstract The results of detailed investigation regarding the ability of defined

MRET polymer compound applied to RF phones to increase the dielectric

permittivity of water based solutions and to reduce the SAR (Specific Absorption

Rate) values inside the “phantom head” filled with the jelly simulating muscle and

brain tissues are presented. MRET polymer generates specific subtle, low

frequency, non-coherent electromagnetic oscillations (optimal random field) that

can affect the hydrogen lattice of the molecular structure of water and

subsequently modify the electrodynamic properties of water and leads to the

reduction of the absorption rate of electromagnetic field by living tissue.

Keywords: SAR values, MRET polymer, dielectric permittivity, electrical

conductivity, piezoelectricity, microwave radiation.

1. Theoretical Concepts

The epoxy polar polymer material is a good example presenting all qualities of

volumetric fractal matrix. A number of studies show that external electromagnetic field

can affect local orientations and phase transitions in polymer crystalline systems of

longitudinal chains. Polar polymers possess comparatively low values of relative

dielectric permittivity (3-15) which means that macromolecules in the molecular

structure of these polymers can be easily displaced by external electromagnetic force.

Subsequently the external electromagnetic field can seriously modify the local

orientation order of the system and affect phase transition parameters and dielectric

properties of the polymer compound. The orientation of the polar groups in

electromagnetic field affects the backbone orientation and determines the resulting

anisotropy of crystalline structure of epoxy polymer introduced to electromagnetic field.

The external electromagnetic field generates an excitation in crystalline structures

of the polymer compound. The existence of orientations and phase transitions in

crystalline systems of epoxy polymer introduced to external electromagnetic field leads

to the origination of subsequent relaxation and strain phases in macromolecular

structures that induces the phenomenon of piezoelectricity. Piezoelectricity is the

electrical response of a material to the change of pressure in molecular structures of

polymer compound. It can only be observed in materials having a non centre-

symmetrical structure and elastic properties. Both properties can be found in polar

polymer compounds.

The introduction of foreign agents (substances) in the parent lattice of epoxy

polymer leads to the effect of superimposed periodicity and, as a result, develops

modulated crystalline structures with specific fractal microstructure, phase transition,



264

network topology and polarity. It is a basic concept of MRET polymer compound

covered by US Patent No: 6369399, April 2002. Due to the fractal structures of MRET

polymer compound and the phenomenon of piezoelectricity this polymer generates

subtle, low frequency, non-coherent electromagnetic field (noise field) that can affect

the hydrogen lattice of the molecular structure of water and subsequently modify the

electrodynamic properties of water. Such resonance interaction, including both a

spatial resonance and a resonance of the oscillating frequency of microscopic orbital

currents of protons in water-molecular hexagons, leads to the process of deviation from

the stochiometric composition of water and to the reorganization of water clathrate

structures with minimum input of energy.

Taking into consideration the scientific fact that living tissue such as muscle and

brain tissues are composed of 70 – 90% of water, it is possible to admit that the

application of MRET polymer compound to RF phones may compensate for the

possible biological effect related to the absorption of electromagnetic radiation by

human body tissues [Moulton, 2006]. It is well known scientific fact that microwave

radiation can penetrate into the living tissues at the depth of 0.3mm – 300 mm

depending on the power and intensity of the radiation. The high frequency microwave

oscillations of RF phones are a perfect carrier for the low frequency signals generated

by MRET polymer material. The interaction of such composed electromagnetic field

with molecular structure of cell water may lead to the modification of dielectric

permittivity and electrical conductivity of cell water, and finally to the reduction of the

absorption rate of electromagnetic field by living tissue.

The mathematical concept and calculations are presented below. Specific

Absorption Rate is defined as the time derivation (rate) of the incremental energy (dW)

absorbed by an incremental mass (dm) contained in a volume element (dv) of a given

density (p):

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

=⎟

⎠

⎞

⎜

⎝

⎛=

pdv

dW

dt

d

dm

dW

dt

d

SAR

(1)

There is a direct correlation between the absorption of non-ionizing electromagnetic

radiation by the exposed tissue and the magnitude of the electric component of the field

applied to the tissue. Specific Absorption Rate can be related to the electric field at a

point by:

p

E

SAR

2

σ

= (2)

where σ – conductivity of the tissue (S/m); p – mass density of

the tissue (kg/m3

); E – electric field strength (V/m).

I.V. Smirnov / The Effect of MRET Polymer Compound on SAR Values of RF Phones 265

The equation for the electric field strength at the point in space which is distant from

the source of electromagnetic radiation is the following:

( )2

4 rqrE πε= (3)

where q – electrical charge (V); ε – dielectric permittivity (F/m);

r – distance from the source of electromagnetic radiation (m).

According to the standard methodology for SAR measurements for the “phantom head”

[IEEE Standard 1528-2003], the electrical conductivity (σ) of simulated brain tissue

(hydroxethylcellullose gelling agent) and mass density of the simulated tissue (p) are

considered to be a constant. Considering this fact it is possible to conclude that any

modifications of the measured SAR values have a direct correlation with the

modifications of the measured electric field strength magnitudes. It is a scientifically

proven fact that low frequency electromagnetic field can dramatically affect the

dielectric permittivity and electrical conductivity of water and water based solutions.

Particularly, the scientists of Novocontrol Technologies GmbH & Co. KG

(http://www.novocontrol.com) provide the following results for measurements of

electrodynamic characteristics of water when the body of water is exposed to the wide

range of electromagnetic oscillations (Fig 1).

2. Electrodynamic Characteristics of Water

Fig 1. The relative dielectric permittivity of water significantly increases from 80 up to 108

and electrical

conductivity of water samples decreases up to 10 times in the frequency range of 0.1 – 1000 Hz.

Measurements were conducted on the samples of deionized and tap water in measurement units with different

size (length and diameter) at 20°C.

I.V. Smirnov / The Effect of MRET Polymer Compound on SAR Values of RF Phones266

In the range of low frequencies of 0.1 – 1000 Hz the relative dielectric permittivity

of water increases from its regular value of 80 up to 108

, and electrical conductivity

decreases up to 10 times. Taking into consideration that MRET polymer compound

generates low frequency oscillations, it is reasonable to admit that these specific signals

can affect the electrodynamic characteristics of the water based jelly in the “phantom

head” slightly increasing the dielectric permittivity (ε) and decreasing the conductivity

(σ) of hydroxethylcellullose jelling agent. Subsequently the increase of dielectric

permittivity (ε) leads to the decrease of the strength of electric field (E) inside the

“phantom head” in compliance with equation (3) and to the decrease of SAR values in

compliance with the equation (2).

In compliance with the equation (2) the decrease of electrical conductivity (σ) of

the simulating tissue jelly should lead to the additional decrease of SAR values, but it is

not reflected in this test results due to the standard methodology of SAR test [IEEE

Standard 1528-2003]. According to the standard methodology only the electric field

magnitudes are measured by the probe and the value of conductivity of the water based

jelly is measured before each test and considered to be a constant during the

computerized calculation of SAR values.

3. Experimental Data

The research data provide evidence that the incorporation of 180 mg of MRET

polymeric material in the RF phones in this experiment does not change location of

“Hot Spot”. The “Hot Spots” remain in the same location as without the MRET

polymer and their amplitudes decrease in 90% of data points (Fig.2) [Smirnov, 2006].

NO MRET polymer material Applied MRET polymer material

Fig 2: “Hot Spot” Area Scan Diagrams; Phone Model: LG VX6000; Frequency: 1900.00 MHz; Max.

Transmitted Power: 0.256 W; Phantom data: APREL-SAM Left Ear; Probe Sensitivity:

1.20 1.20 1.20 μV/ (V/m)2

.

I.V. Smirnov / The Effect of MRET Polymer Compound on SAR Values of RF Phones 267

Conclusions

The application of MRET polymer to RF phones does not significantly affect the air

measurements of RF phone signals and subsequently does not lead to any significant

distortion of transmitted RF signals. In each experiment SAR values were measured in

242 points of “phantom head.” The incorporation of 180 mg of MRET polymer

material in the RF phones showed that “Hot Spots” remained in the same location as

without the MRET polymer and their amplitudes decreased in 90% of data points. In

70% of data points was observed the significant decrease of SAR values in the range of

10% to 60%. The incorporation of MRET polymeric material in the RF phones leads to

the reduction of the majority of SAR values: 19 SAR values out of 20 meaningful SAR

values in this experiment were reduced in the range of 0.3% - 29.0%, and only 1 SAR

value increased by 0.6%. The reduction of SAR values calculated on the basis of E-

field probe measurements inside the “phantom head” confirms that the subtle low

frequency oscillations generated by MRET polymer material actually increase the value

of dielectric permittivity of the simulating brain tissue jelly resulting in the reduction of

SAR values in the “phantom head.”

References

[1] I.V. Smirnov, (2006)“Polymer Material Providing Compatibility between Technologically Originated

EMR and Biological Systems” Explore, Vol.15, No 4, pp 26-32

[2] IEEE Standard 1528-2003, IEEE recommended Practice for determining the Peak-Spatial Average

Specific Absorption Rate (SAR) in the Human Head from Wireless Communication Devices:

Measurement Techniques, October 2003

[3] J.M. Moulton, (2006)“R&D Testing SAR Evaluation, Test Report No: R&D 20060601” RF Exposure

Lab, Escondido, California, pp 1-125

I.V. Smirnov / The Effect of MRET Polymer Compound on SAR Values of RF Phones268

Assessment of the Results of Tightening the Regulations in the Scope of Protecting

the Environment against the Effects of Electromagnetic Fields with a Frequency

of 50 Hz

Marek SZUBA1 Institute of Electrical Power Engineering

Wroclaw University of Technology

Abstract. Scientific research shows a number of biological effects on living organisms exposed to electromagnetic fields with levels similar to those produced by high voltage overhead power lines. As a consequence, a number of countries introduced standards, regulations or recommendations restricting levels of both electric and magnetic fields from overhead power lines. Most of the countries established an acceptable level of the magnetic component of the electromagnetic field at the level close to the 80 A/m but number of countries introduced special restrictions in residential areas in proximity to newly constructed power lines. Lowering the acceptable level of the intensity of the magnetic field will have great economic and financial impact. The effects of more strict regulations regarding protection from the effects of the magnetic 50 Hz field by lowering of the magnetic field levels may be grouped into three categories: technical effects, space and landscape implications and financial impact. The lowering of the maximum acceptable level of the magnetic field will require changes to the structure of new power lines and modifications to the existing power lines, especially those effecting highly dense residential areas. In most cases it will be necessary to replace overhead power lines with underground cables. With existing overhead lines, lowering of the acceptable levels to 0,1-0,2 A/m, will extend the width of the zone along the power line with restrictions to constructing residential housing including hospitals, kindergartens, schools etc. Financial effects of those changes are difficult to evaluate at present. Considering the 50,000 km of overhead power lines currently in use in Poland with voltage 110 kV and higher, it could be expected that those costs will be substantial.

Introduction

Environmental impact of electromagnetic fields generated by overhead lines and other electrical systems is a problem that for many years has been the centre of attention for researchers. The researches conducted so far disclosed numerous biological effects

1 Address: Institute of Electrical Power Engineering, Wroclaw University of Technology,

WybrzeżeWyspiańskiego Street 27, 50-370 Wrocław, Poland, E-mail: [email protected]


269

that can occur in living organisms exposed to the action of electromagnetic fields with the levels similar to those occurring in the vicinity of high-voltage overhead lines. In connection with this fact, many countries introduced the standards, regulations or recommendations limiting the levels of electric and magnetic fields in the environment. Such limits aim at protecting human health against the effects of long exposure to, first of all, the magnetic component of the field. In most countries, permissible values of the magnetic component of the field are close to 80 A/m, i.e. the level recommended by the European Union [1]; however, as it is indicated by recent analyses [2], much lower values are recommended in some countries.

A deeper analysis of this subject indicates slow but systematic tightening of the regulations on health protection against the impact of electromagnetic fields with a frequency of 50 Hz. This gives rise to the questions concerning the prospects of development and modernization of the national transmission and distribution grid, facilities of which are the basic source of the electromagnetic field with a frequency of 50 Hz.

1. Development of the Transmission and Distribution Grid – Needs and

Difficulties in Implementation

The Energy Law Act [3] imposes the obligation of ensuring energy security on the companies dealing with the transmission and distribution of energy carriers, and also obliges them to supply electricity to individual customers countrywide. Development plans prepared by power companies in the scope of supplying energy carriers must take into account the needs of satisfying demand for electricity in all regions of the country, considering the current and future allocation of its sources. In order to satisfy demand of individual regions for electricity, which increases every year by approx. 4-5%, the expansion of the existing power infrastructure is necessary. This concerns, first of all, overhead power lines with a voltage of 110, 220 and 400 kV, however, expansion of the lines and stations with the highest voltage (220 and 400 kV) is the most urgent task.

Figure 1. The length of 220 kV and 400 kV overhead lines per 1000 km2 of the area in various European countries.

M. Szuba / Protecting the Environment Against the Effects of Electromagnetic Fields270

This apparent fact was noticed a long time ago by highly industrialized countries whose power transmission grid is currently much better developed than that in Poland (Fig. 1).

Unfortunately, the currently effective laws are not conducive to implementation of investment projects in the scope of power lines, and thus are a considerable obstacle for development and expansion of technical infrastructure. However, apart from the administrative barrier, a new, equally serious obstacle in construction of highest-voltage power lines may occur. This barrier lies in the anticipated change in regulations on protection against the effects of electromagnetic fields generated by power facilities. Such trends have been observed for several years in various countries, first of all, thanks to reports on possible adverse effects on human health from long action of magnetic fields, generated, among other things, by high-voltage overhead lines. Considering the fact that at present over 12 000 km of overhead lines with a voltage of 220 and 400 kV are in service, the signals coming from different scientific communities about purposefulness of tightening the regulations in the scope of protection against 50 Hz fields must cause very serious anxiety.

The results of one of the largest epidemiological investigations, carried out by G. Draper [4], as well as the report from so called SAGE project (Stakeholder Advisory Group on ELF EMFs. Precautionary approaches to ELF EMFs – [5]) were particularly alarming. These reports, supported to a certain extent by a group of scientists in so called Benevento Resolution [6], makes us to consider potential effects of a considerable decrease in permissible levels of electromagnetic fields, particularly those generated by high-voltage overhead lines.

2. What Are “Safe” Values of the Intensity of the Magnetic Field with a

Frequency of 50 Hz

Although the results of the aforementioned epidemiological experiment [4] have been many times subjected to detailed critical analysis, the most important conclusions resulting from the performed investigations can be compiled in the following items:

• there is a relationship between high incidence of leukaemia in children and a distance of the place of their birth and residence from high-voltage overhead lines,

• if such a relationship is recognised as a cause-and-effect relationship, then approximately 1% of all cases of leukaemia in children living in England and Wales can be attributed to staying within the magnetic field generated by high-voltage overhead lines,

• increased risk of incidence of leukaemia in children occurs in a distance up to approx. 600 m from an overhead line; this effect does not occur in greater distances from a line,

• the magnetic field intensity, at which adverse health effects are no longer observed, can be assumed as a value from the range of 0.15-0.25 A/m,

• the evaluation carried out within the analysed investigations has considerable statistical uncertainty.

The data included in many studies, which present magnetic field distributions in the vicinity of overhead lines in England and Wales, do not correlate with the information concerning the aforementioned distance (about 600 m) and related value of the

M. Szuba / Protecting the Environment Against the Effects of Electromagnetic Fields 271

magnetic field intensity (0.15 – 0.25 A/m) included in the work [4]. The work [5] indicates that in the vicinity of typical 275 kV and 400 kV overhead lines operated by Britons, the magnetic field intensity is lower than 0.32 A/m already at a distance of approx. 60 m from the line axis. Only in exceptional conditions (maximum load or asymmetric load of a power line), the aforementioned values occur in a distance up to approx. 150 m from the line axis. Despite these inaccuracies, it is worth trying to evaluate the level of the magnetic field, which, according to the data included in Draper’s report, is recognized as "safe”. From the technical - and actually - economic point of view, it is important to determine a relationship between the “safe” value of the magnetic field and the distance of the source of the field (overhead line) from residential buildings. This issue seems to be so important, because - according to supporters of tightening the regulations on protection against the effects of the fields - closer vicinity of the line will mean increased hazard from the magnetic field.

From the technical point of view, the problem comes down to determining magnetic field intensity distributions up to the distance of several hundred meters from typical high- voltage overhead lines. It should be demonstrated what magnetic field levels are encountered by people nearly every day, and these values should be compared with the magnetic field occurring in a distance of several hundred meters from high-voltage overhead lines. This issue was discussed in detail in the work [7], and its results indicate that:

• in each analysed power supply system, the magnetic field intensity decreases rapidly along with increasing distance from the source of the field,

• magnetic field intensity in the range from 0.15 A/m to 0.25 A/m is recorded: −−−− at a distance of 100-400 m from a 2-circuit 400 kV overhead line, under

the most unfavourable operating conditions, −−−− at a distance of 300-500 m from a 1-circuit 400 kV overhead line, under

the most unfavourable operating conditions, −−−− at a distance of approx. 200-300 m from a multi-circuit 2x400 kV +

2x220 kV overhead line, under the most unfavourable operating conditions,

−−−− at a distance of approx. 30-50 m from a 1-circuit, medium voltage (15 kV) overhead line, at a typical load for this type of lines,

−−−− at a distance of approx. 5-10 m from a low voltage (0.4/0.23 kV) overhead line supported on brackets located on the façade of a building, at a typical load for this type of lines,

The results of the analyses indicate that a significant percentage of the society making use of electricity is in contact with such type of hazard, if the thesis about harmful health effects of 50 Hz magnetic fields with the levels of 0.15 – 0.25 A/m is true Fortunately, domestic statistics of incidence of diseases monitored in Draper’s investigations [4] as well as the data published in Sweden [8], where this problem is examined exceptionally thoroughly, do not confirm this thesis.

3. Potential Consequences of Tightening the Regulations on Protection against the

Effects of Electromagnetic Fields with a Frequency of 50 Hz

Despite the fact that regulations, standards or recommendations in the scope of protection against the effects of 50 Hz magnetic fields, based on the Council


Recommendation [1], are in force in most European countries, in certain countries, and sometimes only in selected regions of a given country, it is recommended to apply much lower values. This concerns such countries as Slovenia, Sweden, Switzerland or Italy, where the recommendations limiting occurrence of 50 Hz magnetic fields in the environment apply to construction of new power facilities, and first of all - overhead power lines. These problems were characterized more broadly in the work [9], where permissible values of magnetic fields, recommended for use in various countries, were given, as well as the philosophy of introducing the aforementioned field level limits was indicated.

Before presenting the potential consequences of tightening the domestic regulations on protection against the effects of 50 Hz magnetic fields, it is worth paying attention to the scale of potential threat to people, particularly to children, living in the vicinity of high-voltage overhead lines. Assessment of their potential exposure requires, first of all, determining the number of houses (apartments) located in the vicinity of high-voltage overhead lines, and isolating those, in which the children aged 0-14 years live. The assessments indicate that in Poland, percentage of houses (apartments) located in the vicinity of the high-voltage lines, in which magnetic field intensity exceeds the level of approx. 0.25 A/m (the level indicated in the work of G. Draper, above which increased incidence of leukaemia in children is observed), is within the range from 0.3 to 0.5%. Taking for consideration average European standards of annual rate of incidence of leukaemia in children (1 case per 200,000/year) and estimated number of children exposed to the effects of the magnetic field with the values exceeding 0.25 A/m (percentage of apartments – 0.5%), it can be established that in Poland, an increase in incidence of leukaemia in children – if any, would be 1-2 cases a year, at the maximum. If this increase is assumed as inadmissible, then the only preventive measure would be a change in the currently valid regulations on protection against the effects of electromagnetic fields [10]. In these regulations, instead of the currently valid permissible value of 60 A/m – a maximum level of approx. 0.25 A/m should be accepted. However, as it will be demonstrated, the consequences of such changes would be very serious.

Such a substantial decrease in the level of permissible magnetic field intensity in the areas, where residential buildings are located, and in the areas earmarked for construction of residential buildings, is not attainable through applying special technical solutions for construction of power lines. Replacement of the overhead power lines made in traditional technology with the lines on compact supports allows reducing the intensity of the magnetic field by approx. 60%. Increasing the height of supporting structures, recognized as one of the most effective methods of reducing magnetic field intensity, would be a very costly measure and would considerably deteriorate the landscape. Replacement of overhead lines with cable systems, although very effective, would provide excessive financial burden for each power company, not only in Poland. That is because of the fact that the cost of constructing a 400 kV cable line is approx. 10-20 times as high as the cost of the overhead line with the same transmission capacity.

In consequence, the only possible solution is exclusion of the areas neighbouring with an overhead line from the building function (residential buildings). Although such measure is possible from the formal and legal point of view, the cost of such actions would be very high. It can be estimated that at construction of a 100 km section of a 400 kV line, which on the length of 10 km, runs through the areas that can be allocated for residential buildings, the costs of compensations for obtaining easement


appurtenant will be approx. PLN 265 million (assuming the price for 1m2 of the land at the level of PLN 50). The estimation was performed under the assumption that the width of the area excluded from construction of residential buildings will be 2x300 m, while at currently effective regulations - this width is 2x35 m.

Attention should be paid to the fact that, in case of adapting the regulations tightened to such significant extent to the current situation, it will be necessary to exclude large areas from the residential function. Rough estimations indicate that the area of the land around existing and currently operated overhead lines, which would be excluded from construction of residential buildings, will be:

• approx. 5,760 km2 – in the vicinity of a 400 kV line, under assumption that the field with the levels exceeding 0.25 A/m occurs along the line, within a strip with a width of 1200 m (2 x 600 m),



which gives a considerable area of nearly 25,000 km2 (approx. 8% of the area of the country).

Although it is possible to imagine construction of new transmission and distribution systems, which will bypass areas with residential buildings, there is no doubt that the costs of constructing such infrastructure will be several dozen times higher than currently. Whereas, it is difficult to imagine the costs of possible rebuilding of the existing distribution systems in order to adapt them to the requirements suggested in the work [4]. Attention should be paid to the fact that the considerations presented above, including potential effects of accepting the permissible level of magnetic field as approx. 0.25 A/m, concerned solely the issue of the residential

buildings located in the vicinity of high-voltage overhead lines (400, 220 and 110 kV) operated currently in Poland. The need of comprehensive approach to the problem is the reason that other situations of exposure should also be identified. This includes the situations, where people – also children – are exposed to staying within the magnetic fields with the intensity exceeding the level of 0.25 A/m. As it is indicated in the data from the literature [11], the fields with just such levels can occur, inter alia:

• at a distance of approx. 35 m from a 1-circuit medium voltage (15 kV) overhead line, at a typical load for this type of lines,

• at a distance of approx. 8-40 m from a low voltage (0.4/0.23 kV) overhead line supported on brackets located on the façade of a building, at a typical load for this type of lines.

The population staying within these fields has not been determined quantitatively so far, even roughly. If the suggestions contained in the “Draper’s report” [4] are accepted, also this group of people, which seems rather numerous, would be considerably exposed to the increased risk of falling ill with certain, rare types of tumours.

When analysing the problem more broadly, it can be found that 50 Hz magnetic fields with the levels exceeding 0.25 A/m also occur in the vicinity of many electrical appliances commonly used in households. Although the exposure to such fields cannot


be defined as long (continuous) exposure, possible health effects occurring in consequence of use of such appliances should be examined thoroughly.

References

[1] Council Recommendation of July 1999 on the limitation of exposure of the general public to electromagnetic fields: 0 Hz to 300 GHz. 1999/519/EC.

[2] EMF Exposure Standards Applicable in Europe and Elsewhere. Environment & Society Group. Eurelectric, March 2006, Ref: 2006-450-0006.

[3] Act of 10 April 1997 - Energy law. Consolidated text: Journal of Laws: Dz.U. from 2006, No 89, item 625 as amended: Journal of Laws: Dz. U. from 2006, No 104, item 708,No 158, item 1123 and No 170, item 1217, from 2007, Nr 21, poz. 124 and No 52, item 243.

[4] Draper G., Vincent T., Kroll M.E., Swanson J., Childhood cancer in relation to distance from high voltage power lines in England and Wales: a case-control study, BMJ, Jun 2005, Vol. 330, p. 1290.

[5] Stakeholder Advisory Group on ELF EMFs (SAGE). Precautionary approaches to ELF EMFs. First Interim Assessment: Power Lines and Property, Wiring in Homes, and Electrical Equipment in Homes. RK Partnership Ltd. 27.04.2007.

[6] Benevento Resolution. Internet address: http://www.icems.eu/docs/BeneventoResolution.pdf [7] Habrych M., Jaworski M., Szuba M.: Wzajemna odległość pomiędzy budynkami mieszkalnymi a

liniami napowietrznymi wysokiego, średniego i niskiego napięcia różnych typów w aspekcie oddziaływania pola magnetycznego. Elektro-Info, No 3 from 2006, p. 106-108.

[8] Low-frequency electrical and magnetic fields: The precautionary principle for national authorities. Guidance for decision-makers. The Swedish National Board of Occupational Safety and Health.

[9] Szuba M.: Ochrona przed oddziaływaniem pól elektromagnetycznych 50 Hz w świetle postulowanych zmian w przepisach. Materials from ELSAF 2007 Conference (in press).

[10] Regulation of the Minister of Environmental Protection dated 30 October 2003 on permissible levels of electromagnetic fields in the environment and methods of controlling the observance of such levels. Journal of Laws: Dz. U. No 192, item 1883.

[11] Guide: “Linie i stacje elektroenergetyczne w środowisku człowieka”. Collective work edited by M. Szuba. Edition 3, Publication commissioned by PSE S.A. to Biuro Konsultingowo- Inżynierskie "EKO-MARK”, Wrocław 2005.


Electromagnetic Field, Health and Environment 277

A. Krawczyk et al. (Eds.)

IOS Press, 2008

© 2008 The authors and IOS Press. All rights reserved.

Author Index

Agayev, T.M. 86

Aleixo, I. 67

Almeida, G. 67

Alotto, P. 151

Aniołczyk, H. 27

Aponte, G. 162

Asmuss, M. 260

Baldermann, C. 260

Bártolo, M.J. 67

Bauer, E.B. 110

Bednarek, K. 32

Bergeron, R. 110

Bienkowski, P. 229

Botelho, M.F. 67

Botoc, M. 105

Burais, N. 221

Byliniak, A. 3

Cadavid, H. 162

Cardoso, J.R. 47

Carreira, I. 67

Castro, J. 67

Cecílio, J. 168, 176

Cheda, A. 98

Cieslar, G. 72

Ciosk, K. 157

Cordeiro, R. 67

Costa, R. 67

Creangă, D.E. 142

Dabala, D. 105

Dąbrowski, M.P. 98

Dahle, M. 110

Dehos, A. 260

Déniz, F. 38, 43

Díaz, F. 38, 43

Dimitrova, S. 238

Duraj, A. 79

Enge, J. 110

Escobar, A. 162

Estacio, J. 162

Ferreira, C. 67

Fleming, A.H.J. 18, 110

Fujiwara, K. 116

Geschwentner, D. 260

Guarnieri, M. 151

Guneser, C. 53

Hayakawa, T. 122

Hernández, G. 38

Hoang, L.H. 221

Hori, T. 116

Ikehata, M. 122

Ishihara, Y. 116, 207

Janiak, M. 98

Kos-Kudla, B. 72

Krawczyk, A. v, 3, 79, 157, 207,

249, 255

Kreuzer, M. 260

Kubacki, R. v, 98, 126

Lemos Antunes, C. v, 168, 176

Lewicki, F. 244

Lisiecka-Biełanowicz, M. 249

Lopes, M.C. 67

Lucca, G. 188

Ludwiczuk, R. 198

Lusawa, A. 249

Marques, J. 67

Martínez, M. 43

Matsumoto, S. 122

Matthes, R. 260

McIntosh, R.L. 213

McKenzie, R.J. 213

Mekhdiyev, A.A. 86

Miaskowski, A. 207

Miclăuş, S. 105, 133, 142

Mikolajczak, P. 198

Moro, F. 151

Nakajima, M. 116

Neves, L. 67

Nicolas, A. 221

Nowosielska, E. 98

Panakhova, E.N. 86

Pereira Filho, M.L. 47

Pinto, M. 67

Plawiak-Mowna, A. 255

Płonecki, P. 92

Pölzl, C. 260

Pophof, B. 260

278

Pulido, A. 43

Răcuciu, M. 133, 142

Rolo, I. 67

Rotaru, O. 105

Rysz, A. 92

Sadiyeva, A.A. 86

Sahin, O. 53

Santos, A.C. 67

Sauren, M. 213

Sawicki, B. 92

Scorretti, R. 221

Sędek, E. 126

Sekerci Oztura, H. 53

Sieron, A. 72

Smirnov, I.V. 264

Sobiech, J. 126

Sowa, P. 72

Stankiewicz, W. 98

Starzyński, J. 92

Surcel, D. 105

Suzuki, Y. 122

Szanto, C. 105

Szmigielski, S. 98

Szmurło, R. 92

Szuba, M. 269

Szymanski, Z. 58

Tavares, H. 67

Toader, S. 105

Todaka, T. 116

Turri, R. 151

Ueno, S. 8

Valente, H. 168, 176

Wac-Wlodarczyk, A. 207

Wiak, S. v

Wincenciak, S. 92

Wrembel-Wargocka, J. 98

Yoshie, S. 122

Ziegelberger, G. 260

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