occupational exposure of physical therapists

OCCUPATIONAL EXPOSURE OF PHYSICAL THERAPISTS

TO RADIO FREQUENCY RADIATION -

THE SITUATION IN GREECE

KARABETSOS E.1, BASIOUKA M.

2, ZISSIMOPOULOS A.

3

1 GREEK ATOMIC ENERGY COMMISSION, NON-IONIZING RADIATION

OFFICE, P. O. BOX 60092, 15310 AGIA PARASKEVI, GREECE 2

PROGRAM OF POSTGRADUATE STUDIES (M.Sc.) HEALTH AND SAFETY IN

WORKPLACES, DEMOCRITUS UNIVERSITY OF THRACE 3

NUCLEAR MEDICINE DEPARTMENT, MEDICAL SCHOOL DEMOCRITUS

UNIVERSITY OF THRACE, ALEXANDROUPOLIS, GREECE

Abstract

Electromagnetic fields are present everywhere in our environment in the vicinity of all kinds of natural and artificial sources. Artificial sources are encountered in medical environments and are used for different

kinds of treatment. In physiotherapy centers there are many artificial sources (like diathermy) that are used for

the treatment of patients and usually emit high levels of radio frequency radiation.

The purpose of this paper is to investigate the levels of radio frequency radiation to which physical

therapists are exposed during their work in Greece and to relate them with the exposure limit values established

in the International Commission on Non-Ionizing Radiation Protection, ICNIRP: Guidelines for limiting

exposure to time-varying electric, magnetic and electromagnetic fields (0-300 GHz) and incorporated in the

2004/40/EU Directive on the minimum health and safety requirements regarding the exposure of workers to the

risks arising from physical agents (electromagnetic fields).

In this research work, personal E-field monitors were used to record the RF exposure of 30 physical

therapists in their workplaces during their normal working routine, while handling physical therapy equipment

and treating their patients. The devices used are the ESM-30 Radman XT Narda STS radiation monitors that

record the E-field radio frequency exposure of the physiotherapists in the frequency range from 27 MHz to 40

GHz. These monitors were set to record the maximum and average exposure values in every minute.

Physiotherapists kept a log book noting the exact clinical routine and the relevant medical devices used.

The recorded average exposure levels are found in general much lower than the established limits for

occupational exposure. The recorded maximum exposure levels can reach instant values up to 100% of exposure

limits, but these levels become very low when they are averaged over the 6 minute period provisioned in the

guidelines. The results also showed that the higher measured values were associated with the use of certain

medical equipment and clinical practices. In these cases, certain measures for mitigation of personnels exposure are proposed.

Introduction

In physiotherapy departments, occupational exposure to electromagnetic fields (EMFs) is associated

with the electromedical equipment used for the treatment of patients. According to the national legislation, every

physiotherapy center must be equipped with therapeutic devices such as microwave (MW) diathermy (which

operates in the frequency of 2450 MHz), or short-wave (SW) diathermy (operating mainly at the frequency of

27 MHz), laser, ultrasound, infrared heat light, ultraviolet radiation, t.e.n.s. (Transcutaneus Electric Nerve

Stimulation), magneto-therapy, interferential therapy, e.t.c.

Not only the employees but also the general population should be protected against all risks related to

exposure to electromagnetic fields. Therefore, the International Commission on Non-Ionizing Radiation

Protection (ICNIRP) has established basic restrictions and reference levels in its guidelines on limiting exposure

to non-ionizing radiation. ICNIRP s guidelines are incorporated in the 2004/40/EC Directive on the minimum

KARABETSOS E., BASIOUKA M., ZISSIMOPOULOS A.

2

health and safety requirements regarding the exposure of workers to the risks arising from physical agents

(electromagnetic fields). Directive 2004/40/EC was adopted by Parliament and Council in April 2004 and was

due to enter into force in April 2008. Since, it was pointed out that certain matters that are covered by the

Directive need to be reexamined, it is now expected to enter into force in April 2012.

Materials & Methods

As mentioned earlier, 30 physiotherapists participated in this research work. During their working

hours they kept a log book noting the exact clinical routine and the relevant medical devices used. They were

also wearing a special device (the ESM-30 Radman XT Narda STS), a personal radiation monitor that records

the radio frequency exposure of the physiotherapists in the frequency range 27 MHz - 40 GHz. It is a small,

handy, test and warning instrument which provides safe warning of electromagnetic field in the areas of

application. Radman XT measures according to the usual standards. It was worn on the body by attaching it to

clothing using the clip as shown in the photo. The electromagnetic field is measured continuously during operation. The monitors were set to record the maximum and average exposure values every minute.

Radman XT measures isotropically. The electric field is monitored by three independent sensors that are arranged in such a way so that the device always gives the correct result, regardless of its orientation in the

field. When electromagnetic radiation is present, the Radman XT indicates the magnitude of the radiation level

by means of four LEDs (12.5% LED, 25% LED, 50% LED and 100% LED). The x % LED indicates that x %

of the power density permitted by the relevant standard (ICNIRP Occupational reference levels values) has been

reached. Specifically, the 50% LED indicates the first alarm state. This alarm state is indicated by a flashing red

LED. The device also emits an audible beep twice a second as an additional warning signal. This status is

maintained for as long as Radman XT continues to measure this level of electric field strength. The 100% LED

also indicates a second alarm state. This alarm state is also indicated by a flashing red LED. The device again

emits an audible beep, this time 4 times per second. As long as Radman XT continues to measure this level of

electric field strength the beep is heard. By noting the different beep repetition rates, physiotherapists could

easily locate the field maxima without looking at the LEDs. When the device is switched on, if electromagnetic

field is present, it is measured continuously during operation.

Results

For the purposes of this research work, Radman XT was set to record the maximum and average exposure

values in every minute. A new set of data is recorded each time the instrument is switched on. The data sets

were evaluated on a computer with the aid of the appropriate software. All evaluations were summarized and

saved in a report. The saved data set contain the maximum and minimum value from all the electromagnetic

field values that were measured during operation. The form of the measurements as displayed on the computer

is shown on the table below (TABLE 1):

OCCUPATIONAL EXPOSURE OF PHYSICAL THERAPISTS TO RADIO FREQUENCY

RADIATION THE SITUATION IN GREECE

3

TABLE 1

index; date; time; maxE[%];maxH[%] avgE[%];avgH[%]

0;24/02/09;09.15.40 ; 12 5; 0

1;24/02/09;09.16.40 ; 9 5; 0

2;24/02/09;09.17.40 ; 10 5; 0

3;24/02/09;09.18.40 ; 9 5; 0

4;24/02/09;09.19.40 ; 7 5; 0

5;24/02/09;09.20.40 ; 7 5; 0

6;24/02/09;09.21.40 ; 6 5; 0

7;24/02/09;09.22.40 ; 9 5; 0

8;24/02/09;09.23.40 ; 7 5; 0

9;24/02/09;09.24.40 ; 6 5; 0

In the first column the date and time is shown in detail, in the second column the maximum exposure

value and in the third column the average exposure value, all expressed as percentage of the EC Directives action values.

All the measurements results were directly related to the clinical routine as described by the

physiotherapists. Physiotherapists kept a log book noting the physiotherapy devices used in consecutive half

hour time periods of a typical working day. Hence, the following indicative table was created (Table 2):

TABLE 2

TIME EXPOSURE

QUOTIENT

T.E.N.S. INFRARED U/S INTERFERENTIAL

CURRENTS

LASER

09:30-10:00 6%

10:00-10:30 6%

10:30- 11:00 7%

11:00-11:30 6%

11:30-12:00 6%

12:00-12:30 9%

12:30-13:00 6%

13:00-13:30 8%

13:30-14:00 6%

17:00-17:30 7%

17:30-18:00 6%

18:00-18:30 7%

18:30-19:00 6%

19:00-19:30 6%


4

In the graphic chart (Graphic Chart 1) below, the medical devices used in consecutive thirty minutes

time periods are shown.

GRAPHIC CHART 1

Finally, in the Diagram 1, the % percentage of the occupational limit value recorded in consecutive half

hour time periods is shown.

Diagram 1

From the above diagram, it is clear that the exposure quotient is extremely low (does not exceed 10%

of the established limit for occupational exposure). Therefore, the equipment used in this case - infrared heat

light, interferential currents, ultrasound (u/s), laser and t.e.n.s., separately and/or simultaneously during a whole

working day, present almost the same low exposure levels.



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Checking the working program of another physiotherapist the following elements (table, graphic chart

and diagram) were respectively derived :

TABLE 3

TIME EXPOSURE DIATHERMY T.E.N.S. U/S INTERFERENTIAL

CURRENTS

LASER

12:00-12:30 144%

12:30-13:00 144%

13:00- 13:30 144%

13:30-14:00 6%

14:00-14:30 6%

14:30-15:00 6%

15:00-15:30 6%

15:30-16:00 6%

16:00-16:30 6%

16:30-17:00 10%

GRAPHIC CHART 2


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DIAGRAM 2

In diagram 2, it is shown that high exposure levels were recorded during the first one and a half (1 ) working hour of the physiotherapists schedule. These high exposure levels are exclusively related to diathermys function. It needs to be pointed out that this high percentage (144%) was not stable during the whole diathermys operation. It was recorded during the first 2 minutes of every half hour. This can be explained by the fact that during the first minutes of each therapy session, the physiotherapist was standing very

close to diathermy equipment to switch it on and to prepare the patient. Then, the physiotherapist stepped away

and so he was no longer close to this equipment.

As mentioned above, the Radman XT used for the measurements, emitted an audible warning signal

every time that 50% of the power density permitted by ICNIRPs occupational reference levels values was reached. As all physiotherapists stated, every time they switched on the diathermy device the warning signal

was heard. After a while, having stepped away from the diathermy device, the Radman XT recorded low

exposure levels and the warning signal was no longer heard.

Discussion

The main finding of this research work is that the diathermy equipment emits substantially higher

levels of high frequency electromagnetic radiation in comparison to the rest medical equipment used in

physiotherapy centers.

This conclusion can be easily drawn up considering the following: In 14 physiotherapists data files

high levels of electromagnetic radiation were recorded while in the rest 16 much lower values were logged.

After checking every physiotherapists daily working routine, it was noticed that all the first 14 of them have used the diathermy device. For the rest 16, it was noticed that during the specific days that the personal monitor

was given to them, they had not used at all the diathermy device. The medical equipment that they used, such as

laser, t.e.n.s., infrared heating light, ultrasound, interferential currents, magneto therapy, e.t.c. in any

combination does not expose physiotherapists to high levels of high frequency electromagnetic radiation.

12 out of the 14 physiotherapists who used the diathermy device during their working day, stated that

they received the audible signal from Radman XT mostly during the first minutes of the diathermy therapy.

They also stated that they kept hearing the personal monitors alarm signal when they were standing near diathermys electrodes placing them close to the patients body. So, these physiotherapists upon listening to the audible signal were at once aware of the presence of high levels of electromagnetic field and they all noticed

that moving even a few centimeters away from the diathermy device the signal stopped.

These results are in agreement with these reported by Scotte J., [19]. It was observed that the air-gap

electrodes caused the highest levels of electromagnetic radiation. High electric and magnetic fields close to

diathermy equipment have also been measured by Martin CJ et al. [11]. Fields above the recommended whole

body levels extend to 0.5 - 1.0 m from the electrodes and cables for continuous wave (CW) shortwave



7

equipment, and up to 0.5 m for microwave units and pulsed shortwave models. Operators were exposed to local

fields above these values for 2 - 3 min during CW shortwave treatments, but rarely exceeded the recommended

exposure. However, short localised exposures to high fields, which can occur if the operator moves close to the

electrodes or cables, could exceed these limits. Physiotherapists are advised to remain at a distance of at least 1

m during cw treatments, and not to approach within 0.5 m of the electrodes and cables even for a short period.

Li CY and Feng CK [9], in order to assess the physiotherapist's exposure to radio frequency

electromagnetic fields from short wave diathermy equipment, conducted on-site measurements of stray electric

and magnetic fields (27.12 MHz) close to continuous wave (CW) short wave equipment. The results show that

the operator's knees may have the highest exposure level for both electric field (E-field) and magnetic field (H-

field) in the normal operating position, i.e., behind the device console. Physiotherapists were advised to remain

at a distance of at least 20 cm from the electrodes and cables to avoid possible overexposure.

Measurements by Macc et al. [10], conducted in 8 physiotherapy departments, exposure exceeding the limits was found but was substantially minimized when keeping a safe distance. The exposure minimization was

not always achievable when close to the electromagnetic sources where placed metallic items such as chairs,

portable curtins, e.t.c. often found in the electrotherapy room. Di Nallo A.M., et.al. [5] came to the same

conclusions. According to Tzima, Scandurra and Martin [20, 16, 12], when physiotherapists maintain 1 m

distance from electromagnetic sources and metallic objects, then overexposure is not recorded.

Many researchers [3, 7, 11, 12, 16, 18, 20] agree that keeping a safe distance from electromagnetic

sources is very important. According to Casciardi et al, Grandi et al and Shields et al [3, 7, 18] even though high

exposure levels are recorded at a 10 cm distance from these kind of sources, these levels are not high at 1m

distance.

Conclusions

The total number of physiotherapists that participated in this research work was much higher than any

other previous studies in Greece and abroad. According to the reference levels for occupational exposure as

established by ICNIRP [8] and incorporated in 2004/40/EC Directive [6] the results that derived from the

measurements showed high levels of electromagnetic radiation only during diathermys operation. When only the rest of the medical equipment in physiotherapy centers was used, very low exposure values were recorded.

Since there are several occasions in which the limits for occupational exposure are exceeded in a

physiotherapy clinic when the diathermy unit is in use, certain measures should be taken in order to mitigate

workers and general publics exposure. Access in the electrotherapy room should be supervised so that while the diathermy unit is in operation

only the physiotherapist and the patient should be present. When it is absolutely necessary someone else to be

present (i.e. a person accompanying a patient), it is recommended that he maintains a distance of at least 3 m

away from it. The physiotherapist, after placing the patient and switching on the diathermy unit, should step away

from it, if possible at a distance of at least 2 m. In every case the physiotherapist should work in such a way to

keep a safe distance from the diathermy and minimize his exposure near it.

Conclusively, it must be stated that even though the recorded average exposure levels are found in

general much lower than the established occupational exposure limits and the recorded maximum exposure

levels only instantly reach values up to 100% of these limits, it is still very important to keep informing

physiotherapists to follow safe practices in order to minimize exposure risk, keeping also in mind that an

underestimation of the electromagnetic field strength cannot be excluded since the measuring equipment used is

worn on the body [21].

References

1. Bauwens P. and Scott B.O.,The value of measurements in diathermy. Ann. Phys. Med., 1953.

2. Bolte J.F.B., and Pruppers M.J.M., Electromagnetic Fields in the Working Environment, Ministry of Social

Affairs and Employment (SZW) and National Institute for Public Health and the Environment RIVM no.

610015001, 2006.

3. Casciardi, S., Rossi, P. and Campanella, F. Inquinamento elettromagnetico nei reparti di terapia fisica: rilievi

sperimentali e interventi di bonifica dBA 98 Dal rumore ai rischi fisici. Valutazione, prevenzione e bonifica in ambiente di lavoro. Modena 1719 September 1998, 917926, 1998.


8

4. Cooper, T. G., Allen, S. G., Blackwell, R. P., Litchfield, I., Mann, S. M., Pope, J. M. and van Tongeren, M. J.

Assessment of occupational exposure to radiofrequency fields and radiation. Radiat. Prot. Dosim. 111, 191203, 2004.

5. Di Nallo A.M., Strigari L., Giliberti C., Bedini A., Palomba R., Benassi M., Monitoring of people and

workers exposure to the electric, magnetic and electromagnetic fields in an Italian national cancer Institute.

Journal of Experimental & Clinical Cancer Research 27:16, 2008.

6. 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) (2004).

7. Grandi, C., Iavicoli, S., Molinaro, V., Palmi, S. And Rossi, P. Problematiche di particolare interesse

riguardanti la tutela dei lavoratori esposti a rischi di tipo fisico in ambiente sanitario. Prevenzione Oggi 13, 344, 2001.

8. ICNIRP: Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (0-

300 GHz), Health Physics 74:494-552, 1998.

9. Li, C. Y. and Feng, C. K. An evaluation of radiofrequency exposure from therapeutic diathermy equipment.

Ind. Health 37, 465468, 1999.

10. Macca I., Scapellato M.L., Carrieri M., Pasqua di Bisceglie A., Saia B. and Bartolucci G.B. Occupational

exposure to electromagnetic fields in physiotherapy departments Department of Environmental Medicine and

Public Health, University of Padova, Italy, 2007.

11. Martin, C. J., McCallum, H. M. and Heaton, B. An evaluation of radiofrequency exposure from therapeutic

diathermy equipment in the light of current recommendations. Clin. Phys. Physiol. Meas. 11, 5363, 1990.

12. Martin, C. J., McCallum, H. M., Strelley, S. and Heaton, B. Electromagnetic fields from therapeutic

diathermy equipment: a review of hazards and precautions.Physiotherapy 77, 37, 1991.

13. RadMan XT Operating Manual, Narda Safety Test Solutions, Germany, 2008.

14. Ruggera P.S,. Measurements of emission levels during microwave and short-wave diathermy treatments. US

Dept. of Health and Human Services Publication (FDA) 1980.

15. Saunders RD, Sienkiewicz ZJ, Kowalczuk CI, Biological effects of electromagnetic fields and radiation,

UK, 1991.

16. Scandurra, G. Livelli di campo elettromagnetico nelle vicinanze di apparati terapeutici a RF e MW. Med.

Lav. 80, 335340, 1989.

17. Schwan H.P. and Piersol G.M., The absorption of electromagnetic energy in body tissues. Part II,

Physiological and clinical aspects. Phys. Med., 34: 1955.

18. Shields, N., O Hare, N. and Gormely, J. An evaluation of safety guidelines to restrict exposure to stray radiofrequency radiation from short-wave diathermy units. Phys. Med. Biol. 49, 29993015, 2004.

19. Skotte, J. Reduction of radiofrequency exposure to the operator during short-wave diathermy treatments. J.

Med. Eng. Technol. 10, 710, 1986.

20. Tzima, E. and Martin, C. J. An evaluation of safe practices to restrict exposure to electric and magnetic

fields from therapeutic and surgical diathermy equipment.Physiol. Meas. 15, 201216,1994.

21. S. Iskra,, R. McKenzie and I. Cosic, Factors influencing uncertainty in measurement of electric fields close to

the body in personal RF dosimetry, Radiation Protection Dosimetry (2010), Vol. 140, No. 1, pp. 2533.

occupational exposure of physical therapists

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