hypersensitivity of human subjects to environmental electric and magnetic field exposure

7/31/2019 Hypersensitivity of Human Subjects to Environmental Electric and Magnetic Field Exposure

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Hypersensitivity of human subjects toenvironmental electric and magnetic fields(EMFs) has been reported quite recently inthe medical literature. Descriptions of pos-sible allergic reactions from exposure toelectrical environments have been pub-lished principally by European researchers,mainly from Nordic countries. But thereports and probably the cases appear to haveincreased so rapidly that some authors have

labeled this a new environmental epidemic (1).Although the clinical picture was mainlydermatological at the beginning and mostlyassociated with work on video display units(VDUs) (2), it has been extended to severalhealth problems triggered by different kinds ofexposure to EMFs. Health consequences couldbe so serious for some people that they lead tolengthy sick leaves and even sometimes tochanges of jobs and homes (3). Studies ofhypersensitive people are particularly difficult toconduct because symptoms are nonspecific andtheir relationships to EMFs are mainly allegedby the patients but not proved. In fact few etio-logic studies have considered this health issue,and few reviews have been published on it.

This article is an overview of the scientificliterature published on the subject, with a spe-cial focus on the possible causal relationship ofexposure to EMFs of extremely low frequen-cies (ELF; 0.030.3 kHz). For that purpose, aMEDLINE (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) search was carried out fromJanuary 1990 through September 2000, usingthe headings electrical, electric and magneticfields, hypersensitivity, dermatitis, and allergy.Older reports were taken from references of

reports selected at the first stage as well asfrom two recent reports, one from Europe (3)and the other from the United States (4). TheNational Institute for Occupational Safetyand Health database (NIOSHTI) with theCanadian Centre for Occupational Healthand Safety database (OSHLINE) (http://www.ccohs.ca/education/asp/search_hseosh.html)was also consulted, and contacts were estab-lished with European experts to obtain recent

data from Europe. Only reports published inpeer-reviewed journals were considered forthis review.

Definition and Descriptionof the Health ProblemMany terms are used to name hypersensitivityto EMFs. Hypersensitivity to electricityseemsto have been first used by Knave et al. (5) todescribe health problems triggered by expos-ure to VDUs, fluorescent lighting, or electri-cal devices. Electric hypersensitivitywas alsoused to describe similar clinical portraits byBergqvist and Knave (6) and Anderson et al.(7). Other synonyms used are electrosensitivity(8), electromagnetic hypersensitivity(3,4), elec-trical hypersensitivity(4,9), and electrical sensi-tivity (10). A more general term,environmental illness, has also been used byArnetz et al. (11) to describe apparently thesame clinical portrait.

Several definitions have been given forsuch diverse designations. A definition hasbeen proposed recently that seems adequateto us:

electromagnetic hypersensitivity [is] a phenome-non where individuals experience adverse health

effects while using or being in the vicinity ofdevices emanating electric, magnetic or electro-magnetic fields (EMFs). (3)

As imp lied by the ti tle of this rev iew,herein I use the term proposed by theCalifornia Department of Health Services:hypersensitivity to electric and magnetic fields(HSEMF). It seems preferable because in theELF range where electric and magnetic fieldsare considered separately (12). HSEMF isthen defined in this review as a phenomenonwhere individuals experience adverse healtheffects while using or being in the vicinity of

devices emanating electric and/or magneticfields of extremely low frequency.

The clinical portraits are sometimescomplex, but it seems that two general char-acteristics are associated with HSEMF(3,5,13): a) a group of symptoms (syn-drome) usually appears or worsens duringexposure to a specific source of EMFs, usu-ally at work; b) these symptoms are reportedto diminish when patients are away from thesource and especially during absences fromwork (weekends, holidays, etc.).

The dermatological syndromewas the firstto be described in the literature (2,1416).It is mainly related to exposure to VDUs

and mostly has a good prognosis. The symp-toms are primarily subjective (itching, burn-ing, stinging, etc.) and sometimes objectivebut nonspecific (rashes, dry and rosy skin),and are mostly localized to the face. Clinicaldiagnoses of VDU users with skin disorderswere quite commonly facial dermatoses suchas seborrheic eczema, acnea vulgaris, mildrosacea, and atopic dermatitis (1619). Only

Environmental Health Perspectives VOLUME 110 | SUPPLEMENT 4 | AUGUST 2002 613

Hypersensitivity of Human Subjects to Environmental Electric and MagneticField Exposure: A Review of the Literature

Patrick Levallois

Unit de Recherche en Sant Publique, Centre Hospitalier Universitaire de Qubec, and Institut National de Sant Publique du Qubec,Beauport, Qubec, Canada

This article is part of the monograph EnvironmentalFactors in Medically Unexplained Physical Symptomsand Related Syndromes.Address correspondence to P. Levallois, Unit de

Recherche en Sant Publique, Centre HospitalierUniversitaire de Qubec, 2400, rue dEstimauville,

Beauport, Qubec, Canada G1E 7G9. Telephone:(418) 666-7000, ext 210. Fax: (418) 666-2776.E-mail: [email protected]

This article is a revised version of a report preparedfor the California Department of Health Servicesthat was part of the California EMF research pro-gram. This program was mandated by the PublicUtilities Commission with moneys from Californiautilities. This work was done by the author during asabbatical at the California Department of HealthServices, Oakland, CA, USA.

Received 3 December 2001; accepted 4 June2002.

Unexplained Symptoms

Hypersensitivity to exposure to electric and magnetic fields (EMFs) has been reported for nearly20 years; however, the literature on the subject is still very limited. Nearly all the literature pub-

lished concerns a dermatological syndrome that consists of mainly subjective symptoms (itching,burning, dryness) and a few objective symptoms (redness, dryness) appearing after individuals

begin working with video display units and decreasing during absence from work. Casecontrolstudies as well as some good but limited double-blind trials have not found any clear relationship

between this syndrome and exposure to EMFs. A general syndrome with more general symp-toms has been rarely described but seems to have a worse prognosis. The symptoms often associ-

ated with skin disorders are mainly of neurasthenic type and can cover a lot of nonspecificsymptoms present in other atypical syndromes such as multiple chemical sensitivity or chronic

fatigue. Most of these symptoms are allegedly triggered by exposure to different sources of EMFs,

but there have been no valid etiological studies published on this more general syndrome. Itappears that the so-called hypersensitivity to environmental electric and magnetic fields is an

unclear health problem whose nature has yet to be determined. Key words:electromagnetic fields,hypersensitivity. Environ Health Perspect110(suppl 4):613618 (2002).

http://ehpnet1.niehs.nih.gov/docs/2002/suppl-4/613-618levallois/abstract.html


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one case has been reported in NorthAmerica, with dermatological symptoms onhands and forearms that were associatedwith VDU use (20).

The general syndromewas more recentlyreported and seems less defined. Patients aredescribed with various health symptoms asso-

ciated with or without skin problems: func-tional symptoms of the nervous system(dizziness, fatigue, headache, difficulties inconcentration, memory problems, anxiety,depression, etc.), respiratory problems (diffi-cult breathing), gastrointestinal symptoms,eye and vision symptoms, palpitations, and soon (5,13). All are present without any indica-tion of organic lesion. These symptoms aretriggered with exposure to different electricaldevices and appliances (office equipment, flu-orescent lights, household appliances, televi-sions, etc.), and often seem to worsen withtime, with relatively poor prognosis (3).

Descriptive EpidemiologicStudies

Occupational Studies

Four studies have been conducted by self-administered questionnaire to assess the fre-quency of dermatological symptoms and

signs in relation to VDU use in differentcompanies in Europe and Asia. The twomore detailed studies in Sweden were supple-mented with clinical examination of a sampleof the respondents. Those four studies aresummarized in Table 1 with their mainresults. Two were conducted in Sweden

(17,18), one in Singapore (21), and one inthe United Kingdom (22). Participation ratewas excellent, except in the U.K. study. Facialcomplaints were found to be common amongoffice workers and were more frequent forVDU users in the two Swedish studies(17,18). Operators who complained of skinproblems were generally more likely to reportother health problems related to VDU use:eye discomfort or irritation (17,18), muscu-loskeletal symptoms (17,21), and headache(17). Symptoms were associated with dura-tion of work on VDUs but not with the typeof VDU used (18).

Population StudiesNo published epidemiologic study has beenfound on this issue. However, a group fromthe European Commission tried to assess theextent of electromagnetic hypersensitivity inEuropean populations (3). Questionnaireswere sent to 138 center s for occupational

medicine (COMs) and similar organizationsand 15 self-aid groups (SAGs) from 15 dif-ferent European countries. Response rate was49% for the COMs and 67% for the SAGs.Questions were asked about the frequency,type, and severity of cases of electromagnetichypersensitivity. Although it is difficult to

draw statistics from such a semiquantitativesurvey, the report of the EuropeanCommission (3) stated that the prevalenceestimated ranges

from less than a few per million (COM estimatesfrom United Kingdom, Italy, and France) to a fewtenths of a percent (SAGs in Denmark, Ireland,and Sweden) and with severe cases with generallyone order of magnitude of lower occurrences.

Details of the European survey were describedin the appendix of the report. It was foundthat the cases from Northern European coun-tries in particular were associated mostly withwork exposure, whereas cases in Germany and

Ireland were associated only with sources athome. Other countries, such as France,reported mixed exposure. Nervous systemand skin symptoms were more frequentlyreported, and ELF as well as radio frequencysource exposures were reported to be associ-ated with these symptoms.

Unexplained Symptoms Levallois

Table 1. Descriptive studies on skin disorders in VDU users.

Factors associatedAuthors Study population Methods Prevalence with symptoms

Lidn and 400 VDU operators and 150 Survey by self -administered 18.7% of VDU operators reported Subjects report ing skin lesionsWahlberg other office employees not questionnaire (response rate presence of skin lesions on face, neck, had complained more of eye1985 (17) working with VDU from three 97.4%). Questions on past and hands, or arms compared with 15.6% discomfort, muscular skeletalSweden enterprises in the Stockholm present symptoms. Dermatologic for nonoperators (p> 0.05). Higher symptoms, and headache

region. examination on 63% (61) of those frequency of seborrheic dermatitis, (p< 0.05). 18.9% of the

who reported to have current acne, rosacea, and perioral dermati ti s subjects with objective lesionssymptoms on face, cheek, hands, among the exposed (p> 0.05). suspected that these have beenor arms (46 exposed and 15 worsened by their work.reference subjects).

Koh et al. 694 VDU operators in two Self-administered questionnaire 13.4% of PDS users had skin disorders 53% of PDS users reporting skin1990 (21) statutory boards. 40% used survey on past or present skin in the last year, 11.4% for the CRT disorders in the last year felt thatSingapore PDS; 60% used CRTs. symptoms, 96.8% response rate. users (p> 0.05). 7.1% of PDS users their symptoms were improved

reported having skin disorders at present, during weekends and while off duty;7.7% in CRT users (p> 0.05). Skin 30.4% for those working on CRTrashes present at the time of the study (p> 0.05). Operators who complainedlocated mainly on hands, forearms, of skin problems were more likelyhead, and neck. to have musculoskeletal symptoms

of shoulder, low back, and complaints about the work environment.

Berg et al. 3,877 randomly selected Self-administered questionnaire Facial skin problems in the last 2 years: No difference observed among1990 (18) employees from 36 on rashes and symptoms of skin 18.8% in the group without exposure to workers using different VDUsSweden companies in four Swedish disorders with indication of the site VDU, 34.7% in the group of VDU users with larger static and magnetic

cities. of symptoms within the last 2 years, (p< 0.0001). There was a tendency for an fields. Eye irritations more commonresponse rate 96.6%. 809 persons increase of symptoms with increasing use in the group of VDU users with atrandomly selected for clinical of VDUs: RR = 1.96 (1.742.21) for those least 20 hr/week.examination, response rate 92%. with at least 20 hr of VDU use per week.

At the examination, nonspecific skin symp-toms were found more frequently in themost exposed group (RR = 2.98; 1.257.07).

Carmichael and 3,500 public office workers Self-administered questionnaires on 14% of VDU users volunteered a None were studied.Roberts in Swansea; half considered skin problems, response rate 41%. facial complaint at the time of the1992 (22) VDU operators (working survey or within 6 months, 11%United Kingdom >2 hr/day at VDU). among nonusers (p> 0.05).

Abbreviations: CRT, cathode ray tube; PDS, plasma display screen.


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We recent ly reported the resu lt s of apopulation study of HSEMF done by tele-phone survey in California. The details of thisstudy are presented in this issue (23). Out ofa sample of 2,037 Californians, about 3%reported HSEMF, and 0.5% had to changejobs because of it. But no validation of the

answers of the respondents was provided.Compared with power lines and distributionlines, hair dryer use was found to be thesource of EMFs the most strongly associatedwith self-reported HSEMF.

Etiological EpidemiologicStudiesMost of the etiological studies conducted onHSEMF and published in peer-reviewedjournals have focused on skin symptoms andVDU use. Casecontrol and experimentalstudies (provocation studies) have tried toassess the role of exposure to EMFs as well asother environmental factors.

CaseControl Studies

Three casecontrol studies, focusing on skindisorders in relationship to VDUs, have beenpublished. All were conducted in Sweden andare summarized in Table 2.

One (24) was rather limited regarding theassessment of cases, sample size, and environ-mental evaluation. Despite their statistical sig-nificance, the results of hormonal changes aredifficult to interpret. They might be normalvariation or due to factors not controlled inthe experiment. The two other studies (19,25)

have higher quality, with dermatologicalassessment of skin lesion, environmentalassessment with EMF measurements, andorganizational and psychological evaluation byquestionnaire. These two studies found associ-ation of nonspecific skin disorders with VDUuse and also with workload. One found asso-

ciation with exposure to background electricfield intensity but no direct relation with mag-netic fields emitted by the VDUs (25). Thesethree studies observed some type of relation-ship of health status with the VDU use, butno direct link was found with EMF exposurefrom VDUs.

Experimental Studies

Five provocation studies on subjects withskin disorders associated with VDU use andwhose results were published in peer-reviewedjournals were found. Two are from Norway(26,27) and three from Sweden (7,28,29);they are summarized in Table 3. The five

used a double-blind crossover design and onlyone used a control group (29). In three stud-ies (2628), exposure was produced by realVDUs during a working session on eitherVDUs with modification of exposure byscreen filter (26,27) or a different type ofVDU (28). The other two studies (7,29) usedthe VDUs (on or off) only as a source ofEMFs without having the subjects work withthem. All assessed real exposure from EMFs[ELF or very low frequency (VLF; 3100kHz)] at a distance of 3050 cm from theVDUs. All used standardized questionnaires

for symptom evaluation; two used dermatolo-gists for clinical evaluation (26,28), and twoused blood sampling for hormone evaluation(7,29). The quality of the methodology inthese experimental studies is considered good,but sample sizes are limited (1635), andsimple statistical analyses are provided by the

authors. All the studies were negative exceptone, which gave an equivocal result (26) butwere not reproduced in a more robust studyin terms of number of subjects and durationof the experiment (27). Globally, all thesestudies confirm that skin disorders alleged tobe associated with VDU use are not related toEMF emission from VDUs. No study foundthat reaction of subjects was related to fieldintensity. But skin disorders were associatedwith perception tha t the source emission(7,29) was on and with duration of work(26) and low humidity (28).

Very few studies were done on subjectswith a more general syndrome. Rea et al. (30)

presented the results of a study that theylabeled preliminary. One hundred patientstreated for some type of environmental sensi-tivity (the authors briefly mentioned they hadbeen previously evaluated and treated for bio-logical inhalant, food, and chemical sensitivi-ties) and who complained of being EMFsensitive were evaluated in a single-blindscreening. They were challenged for 3 min atdifferent frequencies from 0.5 Hz to 5 MHz.The mean intensity of the fields was pre-sented as approximately 2,900 nT at floorlevel and 350 nT at the level of the chair in

Unexplained Symptoms Review of hypersensitivity to EMFs

Table 2. Casecontrol studies of skin disorders and VDU exposure.

Authors Subjects Methods Results

Berg et al. 19 cases and 28 controls randomly selected among Study carried out on a typical workday and a More associated eye complaints among1992 (24) 809 office workers using VDU at least 20 hr/week. day of leisure. I tching behavior registered by subjects with skin complaints (p< 0.001).Sweden Cases defined as subjects reporting facial skin a nurse, psychological measurements, blood Prolactin and thyroxin elevated and

symptoms. and urinary samples for various hormones. testosterone decreased in those withsymptoms during the workday (p< 0.05).Registered itching and mental strain moreimportant among subjects with symptoms(p< 0.05).

Bergqvist and Cases and controls defined after clinical examination VDU use, individual and organisational variables Nonsignificant increase of OR among VDUWahlberg of 299 subjects volunteered among 323 respondents assessed by questionnaire. Environmental users for seborrheic eczema, erythema, and1994 (19) to a questionnaire of 353 office workers. 76 cases assessment: wall-to-wall carpets, room size, symptoms, without any relationship withSweden with any dermatologic diagnosis (22 cases of relative humidity measured daily 1 week before duration of use. OR increased for erythema

seborrhoeic eczema, 19 cases of acne, 5 cases of the dermatologic exam, static charge, electro- among those who perceived their work pacerosacea, 14 cases of lentigo) and 17 cases with static field and low frequency EMF from the as high and especially in VDU users withsigns of nonspecific erythema. The 223 noncases VDU measured. Potential confounders considered: limited rest break (OR = 7.86; 95% CI: 0.9069).were used as controls. age, gender, perceived lack of influence, limited Low relative humidity (30%) associated

rest break opportunity, stomach-related stress with seborrheic eczema similar in VDU usersreactions. and nonusers. No association with EMF

measurements.

Sternberg et al. Cases and controls selected among 4,943 office Clinical dermatologic examination for cases and Facial erythema and rosacea more prevalent1995 (25) workers. Case: an employee reporting itching, controls. Psychological, organizational, and in cases. Factors significantly associatedSweden stinging, tight or burning sensation in facial skin general environmental evaluation done with with case status in multivariate analysis

and facial erythema or dry facial skin every week questionnaire. Measurements of electrostatic were: workload/support index (OR = 3.7,during the last 3 months. Referents matched for and frequency EMF at the work stations. 95% CI: 1.310.3), VDT work for at leastage, gender and geographic area. 85 cases 4 hr/day (OR = 2.6; 95% CI: 1.06.5), back-chosen randomly among cases and the same ground electric field >30 V/m (OR = 3.2; 95%number of controls. CI: 1.010.2).

Abbreviations: CI, confidence interval; OR, odds ratio.


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which the patient sat while being exposed.The imprecision of the exposure meas-urements and the adequacy of the exposuresettings were settled in a letter to the editorfrom Bergqvist and Franzn (31). Of the 100patients first challenged, 25 reacted positivelyto exposure, with only one reaction to expo-sure to a placebo. These 25 were comparedwith 25 healthy volunteers for a double-blind

challenge. No detail was given on thosevolunteers or on the double-blind setting. Ofthe 25 hypersensitive patients, 16 (64%)reacted positively, the majority (53%) reactingto exposure compared with a few (7.5%) whoreacted to a blank challenge. In fact, most ofthe results presented are incomplete, and itwas stated that no reaction to any challenge,active or placebo, was found in the volunteer

group. The major symptoms reported by thepatients tested were mainly neurological, car-diological, and respiratory. In fact, many ofthe data are imprecise; therefore, it is difficultto give credence to these results. The samegroup tried to reproduce these results with animproved design but without success (3,32).

Results of other types of experimentalstudies have been published recently .



Table 3. Experimental studies on subjects with skin disorders associated with VDU use.

Authors Subjects Methods Results

Swanbeck and 30 patients referred to dermatologists for Double-blind crossover design: Two PCs (A and B) Most of the patients experienced their usual skinBleeker skin problems felt to be caused by VDU use with different emissions were used successively. problems (mostly heat or reddening, itching,(1989) (28) Half of them had one of the following skin Magnetic field (1300 kHz) intensity at 30 cm stinging) when working with VDU but no differenceSweden problems before starting to work on VDU: in front of the VDU: 50 nT (A) and 800 nT (B) between exposure to computer Aor B: 22 reacted

eczema, sebor rhea, dryness, psorias is , elect rostat ic field: 0.2 kV/m (A) and 30 kV/m (B) . to computer A and 23 to computer B. Symptoms

rosacea, or ictyosis Three hours work randomly assigned on A or B on 2 remarkably reduced when relative humidity wasconsecutive days. Patients filled out questionnaires increased from 25 to 60% with no differenceabout symptoms. Dermatologist evaluation 20 min regarding the type of VDU. Of the 13 reacting atand 420 hr after the exposure. high humidity, 11 reacted when exposed to a VDU

switched off and covered with a cloth. Only slightredness was found on some of the patients withcomplaints, but one patient had a Quinckes edema.

Oftedal et al . 20 subjects with skin symptoms associated Double-blind crossover design: Subjects working with Symptoms were less frequent when filters(1995) (26) with work on VDU. 5 subjects had already VDU during 6 weeks at their own workstation: 2 weeks were used and the reduction was stronger forNorway a facial skin disorder (acne, seborrheic without screen filter, 2 weeks with one filter, 2 weeks the first filter used. Tingling, pricking or itching

dermatitis, and atopic dematititis) . 12 with an other filter. Exposure to each filter was randomly were significantly less pronounced when activesubjects had already experienced fewer selected: one supposed to be active and the other filters were used but not other symptoms.symptoms after using a screen filter. inactive. The two filters reduced significantly the electro- Dermatologic evaluation: no difference between

static field but active filters reduced more effectively active and passive filter. Symptoms moreELF and VLF electric fields. No reduction of magnetic pronounced on days with long duration of workfield (ELF or VLF) was provided by the filters. Symptoms with VDU.evaluated by questionnaire each day and signs evaluatedby dermatologist at the end of each exposure period.

Andersson et al . 16 patients referred by occupational Double-blind crossover design: After a rest period of 15 Subjects could not discriminate between the(1996) (7) physicians and dermatologic clinics. min, patient seated for 30 min in front of a personal two exposure conditions (on or off). NoSweden Inclusion criteria: clear subjective reactions computer (PC) at a 50- to 60-cm distance. Each subject relationship between subjective symptoms ratings

in the sk in of the face wi th exposed to tested 4 times (twice wi th PC on and twice of f) . and the actual presence of the field. Symptomsenvironments with electricity for at least 6 Magnetic fields intensity at 50 cm of the VDU: 245 nT were significantly more intense when subjectsmonths and reacting within 30 minutes to (ELF) and 19 nT (VLF). Electric field: 7 V/m (ELF) and felt that the PC was on. No relationship betweentest equipment. All reacted to VDU and 10 V/m (VLF). Questionnaire compared symptoms before levels of hormone and exposure status.sometimes to other electric sources. and after each test. Blood samples for prolactin, testos-14 subjects had made adjustments at work terone, dehydroepiandrosterone, and cortisol takenbecause of their hypersensitivity, and two before and after each test.were on full-time sick leave.

Oftedal et al . 35 subjects se lected by questionnai re Double-b lind crossover des ign: First week VDU work Sever ity of symptoms not di fferent between(1999) (27) distributed to office workers, telephone without filter, then two periods of 3 months of work periods with active or passive filters. StatisticalNorway interview, and electric field measurements in with active or passive filter chosen at random. significant reduction of symptoms compared with

front of the workers VDU. Inclusion criteria: Average reduction between active and passive filter at period without filter for: skin symptoms (heat,at least one facial symptom reported in 60 cm of the VDU: 4.3 V/m for ELF and 0.23 V/m for VLF. burning sensation or stinging; tingling, pricklingconnection with VDU and reduction by a Questionnaire on severity of skin symptoms as well as or itching, sensation of tightness or dryness;filter of ELF or VLF electric field by 40% eye discomfort and nervous system symptoms at the redness or flushing), eye discomfort (stinging oror more. end of each day and a questionnaire on physical and dryness, pain, redness, tiredness, and light

psychological factors at the end of each exposure sensitivity) , nervous system (headaches, tiredness,period. or fatigue). Symptoms were constant during

exposure period regardless of the order of thefilter or the intensity of the reduction of theelectric fields by the filter.

Lonne-Rahm 24 patients recruited by advertisements in Two double-blind experiments with 12 cases and 12 Patients reported increased skin symptoms whenet al. newspapers or referred by dermatologists. controls: Both groups exposed to 30-min periods of they believed that electromagnetic field was(2000) (29) Inclusion criteria: minimum of 6 months of high or low stress, with and without exposure to turned on. No differences were found betweenSweden skin symptoms, reported to appear within 30 electromagnetic fields from a VDU. Matched controls on and off blind exposure. Inflammatory

minutes of exposure to EMF. 12 controls were tested twice with similar exposure but with the mediators and mast cells in the skin were notmatched to cases for age, gender, and fields turned on every time. Stress induced by requiring affected by the stress exposure or by exposure topigmentation ability. participants to act with random sequence of flashing EMFs. No effect of the fields on hormone levels

lights while solving mathematical problems. Magnetic and no difference between cases and controlsfields intensity measured at 50 cm from the VDU: 198 nT for blood hormones.(ELF), 18 nT (VLF). Electric field intensity: 12V/m (ELF) and10 V/m (VLF). Blood samples for adrenocorticotrophichormone, prolactin, growth hormone, melatonin. Skinbiopsies analyzed for the occurrence of mast cells.

Abbreviations: PC, personal computer.


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Sandstrm et al. (9) presented a report of achal lenge with f l icker ing l ight in 10patients with HSEMF symptoms and 10controls. Patients were found to react moreintensely than controls to the exposure, asassessed by visual evoked potentials. Theauthors concluded that the patients labeled

as HSEMF are hyperreactive to environ-mental stimulation such as flickering.Because of its sample size, this study shouldbe considered preliminary, and no relationwas evident between the findings and thesymptoms reported by HSEMF patients.

More recently, Trimmel and Schweiger(33) reported the results of a double-blindtrial to evaluate the effect of a 1-hr exposureto ELF (50 Hz, 1 mT) on concentration andmemory. They found that among 66 volun-teers, subjects self-rating themselves as sensi-tive to EMFs tended to perform less well thanothers when exposed to noise and EMFs.Exposure to noise only had no effect, but the

effect of EMFs only was not evaluated, andfew details are given on the exposure setting.

In summary, most of the experimentalliterature is concerned with VDU skin disor-ders. At present there is no scientific evi-dence for a link of these disorders withexposure to EMFs, either ELF or VLF. Thegeneral syndrome of HSEMF has not beenseriously evaluated by researchers. Tworecent preliminary studies found thatpatients labeled as HSEMF reacted differ-ently to different environmental exposures(flickering light, noise plus EMFs) fromnon-HSEMF patients.

Discussion

The result of the literature review is rathermeager. Few studies have been published onthe subject of HSEMF in peer-reviewed jour-nals. Most of the studies published onHSEMF come from Nordic countries and areconcerned with nonspecific skin disordersrelated to VDUs. Few studies have been con-ducted in other countries and almost nothingcomes from North America. The evidence ofthe existence of a more general syndromeassociated with HSEMF (including such dif-ferent nonspecific symptoms of the nervoussystem as fatigue, dizziness, headache, anddepression) is still very weak.

No evidence exists of a link between

VDU skin disorders and exposure to EMFs,but there is some evidence of a link withorganizational factors and possibly physicalfactors such as humidity. Moreover, theprovocation studies aimed at evaluating theeffect of EMF exposure in a double-blindsetting failed to reproduce the symptoms oflabeled HSEMF patients, and several indi-cators demonstrated the important psycho-logical factors in the emergence of such ahealth problem.

Globally, the largest amount of theevidence pleads against a role of EMFs in thereported symptoms and, moreover, its exis-tence in North America has yet to be demon-strated. But the quality of the research on thissubject is limited. No good descriptive study isavailable on the burden of the health problem

at a population level, and most of the etiologi-cal research on HSEMF has concentrated onVDU exposure. Methodological problems arealso an issue.

First, most if not all the cases reported areof subjects who diagnosed themselves asHSEMF cases. No clear case definition exists,and no recognizable criteria are available toconfirm this diagnosis. Presentation of symp-toms and the alleged causes for the symptomsvary greatly from one country to another, andthere is doubt about the specificity of thecases reported. Developing a case definitionfor such a symptom-based condition is not asimple task, but it is a necessity to improve

study quality (34). Some authors have specu-lated on the possible relation to multiplechemical sensitivity and other related clinicalportraits (24). This relationship certainlyshould be clarified to evaluate the specificityof the HSEMF syndrome.

Most studies on HSEMF are also limitedby the data available on the exposuresreported by subjects or evaluated in studies.The descriptions of the exposure triggeringthe symptoms is usually rather vague. In gen-eral, the exposure reported refers to sourcessuch as VDUs, which are not usually recog-nized as important sources of high-intensityexposure to EMFs (35,36). However, the

importance of computer use on personalexposure to 60-Hz magnetic fields when con-sidering 24-hr exposure was recently demon-strated (37). Most of the controlled studiesdid not evaluate the effect of different kindsof exposure to EMFs (e.g., varying frequency,intensity and time course of exposure) butinstead focused on a simple exposure settingcorresponding to what was usually reportedby patients. Usually, no data on quality con-trol of the exposure setting were provided.

Because of the absence of a good case def-inition and the limited methodology of thestudies on HSEMF, it is difficult to deter-mine completely the nature of this possiblehealth problem. The fact that SAGs seem to

attract a large number of people who claimthat they suffer from HSEMF is rather in-triguing (38). More studies are certainlyneeded to clarify the nature of the healthproblem labeled HSEMF.

To my knowledge, few expert groupshave reviewed the literature on this topic.In 1991, the International RadiationProtection Associat ion, via i ts Non-Ionizing Radiation Committee, issued astatement regarding the alleged radiation

risks from visual display units (39). Itconcluded its review: Based on currentknowledge, there are no health hazardsassociated with radiation or fields fromVDUs. Further research on the possibilitythat skin disorders may be related to VDUwork was recommended.

In 1994 an advisory group of theNational Radiological Protection Board ofthe United Kingdom published a report onhealth effects related to the use of VDUs(40). The report focused mainly on reproduc-tive outcomes, but a section was devoted toskin problems. It concluded,

Skin diseases do not appear to be caused by theelectric fields from VDU, although there is anec-dotal evidence unsupported by epidemiologythat in conditions of low humidity the associatedelectrostatic fields may aggravate existing skinproblems.

In 1997, the European Commissionpresented a report on the possible health

implications of subjective symptoms and elec-tromagnetic fields (3). It concluded, Thereview was unable to establish a relationshipbetween low or high frequency fields andelectromagnetic hypersensitivity. They rec-ommended adequate handling of seriouslyafflicted individuals. Because of the inabilityto clearly describe the syndrome and causa-tion of electromagnetic hypersensitivity, fur-ther research was also recommended.

Finally, in its Working Group report onEMF health effects, the National Institute ofEnvironmental Health Sciences presented abrief review of the topic of electromagnetichypersensitivity (4). This section concluded:

Some individuals have subjective symptomsapparently related to [VDU] use in the office envi-ronment. The evidence is inadequate to relatesuch symptoms to the EMF associated with thatuse. . . . No high-quality double-blind challengestudies have been conducted that conclusivelyestablish the existence of sensitivity to EMF.

In other respects, I consider that the issueof hypersensitivity should not be limited to theHSEMF studies reviewed in this article. In abroader sense, hypersensitivity could mean thegreater susceptibility of an individual to EMFeffects. This could potentially be found for dif-ferent outcomes possibly related to EMF expo-sure. For instance, some studies found thatcertain subjects might be more sensitive to the

effect of EMFs on melatonin secretion(41,42). Although this is still preliminary evi-dence and not synonymous with adversehealth effects, it seems to support the possibil-ity of individual susceptibility to EMF expo-sure. Research on such a topic should focusnot only on the rather nonspecific symptomsof hypersensitivity described in HSEMFreports but also on well-diagnosed illness.

Individual variations to electric fieldperception have been described previously


Unexplained Symptoms Review of hypersensitivity to EMFs


6/6

but at higher intensities than those usuallyfound in the environment and without refer-ence to symptoms of HSEMF (4). As a mat-ter of fact, the field intensities used in thecontrolled studies reviewed were not per-ceived by the patients suffering fromHSEMF. Recently, Leitgeb (32) described

variability in the perception of induced cur-rents in 606 subjects. Although 2% of thesample seemed particularly sensitive to thecurrents, no individual reported symptomsof HSEMF. Although the issue of hypersen-sitivity is still open, it seems clear that thereare variations of perception of EMF expo-sure, but this does not appear to be relatedto HSEMF symptoms.

Conclusion

To date, the literature on hypersensitivity toEMFs is rather meager and suffers frommethodological problems. Most of the pub-lished studies were done in the Scandinavian

countries and focused on dermatological dis-orders. The other clinical portraits are rarelywell described. Globally, case def init ion isunclear, and few population studies have eval-uated the prevalence of this disorder. Themost-studied clinical portraits (dermatologi-cal problems associated with VDU work)were evaluated in casecontrol and in con-trolled studies, and no consistent relationshipwas found with EMF exposure.

In conclusion, I found no substantialgrounds on which to build a framework forhelping a risk assessor to take into accountthe alleged HSEMF syndrome. Our knowl-edge of the nature of the problem seems too

vague to integrate it into an EMF risk assess-ment protocol. But there are certainlygrounds for further research to assess morecarefully its nature and its possible burden inNorth America.

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