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Int. J. Hyg. Environ. Health 207 (2004); 141 ± 150
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//
www.elsevier-deutschland.de
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intjhyg
International Journal
of Hygiene and
Environmental Health
Symptoms of ill health ascribed to electromagnetic field exposure ±
a questionnaire survey
Martin Rˆˆslia, b, Mirjana Moserc, Yvonne Baldininia, Martin Meierc, Charlotte Braun-Fahrl‰ndera
aInstitute of Social and Preventive Medicine, University of Basel, Basel, Switzerland
bDepartment of Social and Preventive Medicine, University of Bern, Bern, Switzerland
cSwiss Federal Office of Public Health, Bern, Switzerland
Received April 22, 2003 ¥ Revision received October 9, 2003 ¥ Accepted October 12, 2003
Abstract
From June 2001, health questionnaires were distributed to people who complained about
symptoms of ill health which they ascribed to exposure to electromagnetic fields (EMF). The
objective of the survey was to gain a better knowledge of the anxieties of complainants, to
obtain hints of possible problems and of actions that should be taken to solve the problems.
The survey was not designed to establish a causal association between exposure to EMF and
symptoms of ill health. Within one year, 429 questionnaires were returned of which 394
persons reported symptoms. The average age of the complainants was 51.0 years and 57
percent were female. The complainants were older, had a higher educational level and were
more likely to be married compared to the general Swiss population. A mean of 2.7 different
symptoms were reported. Sleep disorders (58%), headaches (41%), nervousness or distress
(19%), fatigue (18%), and concentration difficulties (16%) were most common complaints.
Complainants related their symptoms most frequently to exposure to mobile phone base
stations (74%), followed by mobile phones (36%), cordless phones (29%) and power lines
(27%). No distinct symptoms related to a specific field source could be identified. Eighty-five
percent of the people who consulted a public authority because of their symptoms were
unsatisfied with the response, whereas consultation of self-help groups or building ecologists
usually fulfilled expectations. Two thirds of complainants had taken some action to reduce
their symptoms. The most common measure was to avoid exposure if possible. Removing or
disconnecting indoor sources was judged to be the most effective action.
Key words: Electromagnetic fields ± mobile phone base station ± electromagnetic
hypersensitivity (EHS) ± complaints
Introduction
Nowadays, technical electromagnetic fields (EMF)
are ubiquitously present in buildings and in the
natural environment. In parallel with the increasing
exposure to EMF over the last years, an increasing
number of people have been claiming that they are
hypersensitive to electromagnetic fields. Such pa-
tients suffer generally from unspecific symptoms of
ill health such as headaches, sleep disorders, skin
rash, dizziness, etc. Estimates of the prevalence of
people suffering from electromagnetic hypersensi-
1438-4639/04/207/02-141 $ 30.00/0
Corresponding author: Martin Rˆˆsli, Department of Social and Preventive Medicine, Finkenhubelweg 11, CH-3012
Bern, Switzerland. Phone: 41 31 631 3867, Fax: 41 316313520, E-mail: Roeoesli@ispm.unibe.ch
tivity (EHS) vary. While some earlier studies have
assessed that a maximum one percent of the general
population is afflicted (Bergqvist, 1997; Silny,
1999), a recently conducted population survey in
Stockholm reported that 1.5 percent of the popula-
tion identified themselves as suffering from EHS
(Hillert et al., 2002). In a survey in California 3.2%
(95%-CI: 2.8% ± 3.7%) of the population reported
hypersensitivity to exposure to EMF (Levallois
et al., 2002). A similar result came out in a recent
study which used a more objective procedure to
determine EHS (Leitgeb and Schrˆttner, 2003).
Though many acute health effects have been cited,
the results of controlled experimental studies have
been contradictory (Stenberg et al., 1995; Rea et al.,
1991; Radon and Maschke, 1998; Oftedal et al.,
1995; Mueller et al., 2002; Hietanen et al., 2002;
Flodin et al., 2000). Thus, a direct causal link
between exposure to electric or magnetic fields
below recommended reference levels and self-repor-
ted symptoms has not been established to date.
There is no specific symptom profile or validated
diagnostic criteria to diagnose EHS (Levallois,
2002). Apart from a pure EMF phenomenon, other
causes of EHS, such as distress, neuroticism, psy-
chiatric morbidity, and an influence of the public
debate have been considered (David et al., 2002;
Lonne-Rahm et al., 2000; Frick et al., 2002).
In Switzerland, the public discussion about EHS
rapidly increased during the mid nineties, when the
expansion of the mobile phone systems led to many
new base stations. Many people were concerned
about adverse health effects and some reported
symptoms of ill health related to mobile phone base
stations to public authorities, self-help groups,
building ecologists and physicians. A need to react
to increasing concerns about possible health hazards
from EMF has been recognised. Thus, the Swiss
Federal Office of Public Health commissioned the
authors to develop a questionnaire to measure
symptoms and to identify suspected EMF sources
of the afflicted population. A further objective of this
survey was to characterize the afflicted population
and to compare it to a representative sample of the
Swiss population. The third aim was to obtain hints
of possible associations between reported symptoms
and EMF. The fourth objective was to obtain a better
knowledge about who has been consulted and what
steps had been undertaken by the complainants to
improve their situation.
Materials and methods
The questionnaire was designed for people who com-
plained about symptoms of ill health that they associated
with exposure to electromagnetic fields. The question-
naire included questions about symptoms of ill health,
exposure to EMF sources, measures and consultations
that have been taken, the general health status and
demographic characteristics. Open questions were used
to ask about symptoms of ill health to reduce possible bias
in responses. Exposure situation was measured by a given
choice of the most important EMF sources in the daily life.
For each source the complainants had to estimate the
exposure in minutes per day or distance to living place or
work place. In addition, complainants were asked to state,
for each source, how sure they were that the source caused
their symptoms. With another set of questions complai-
nants were asked about measures and consultations they
had been undertaking and how satisfying those measures
and consultations were. Questions about the general
health status were mainly adopted from the Swiss Health
Survey (SHS) from 1997. Additionally, questions from the
Coping Inventory for Stressful Situations (CISS) (Endler,
1999) were incorporated. Demographic questions were
included to measure age, gender, education, living ar-
rangements, etc.
In June 2001, the EHS survey was presented to public
authorities, building ecologists, telephone companies and
other bodies which may be consulted by the afflicted
population. These institutions motivated people to fill in
the questionnaire if they were ascribing their symptoms of
ill health to exposure to electromagnetic fields. Then, the
Swiss Federal Office of Public Health sent a questionnaire
to complainants who agreed to participate. Question-
naires were collected throughout one year.
Data were analysed using S-Plus 6.0. Group differences
were tested using chi-square analysis. Statistical compar-
isons of proportions were conducted assuming binomial
distributed data. Comparisons between the EHS survey
and the Swiss Health Survey (SHS) were adjusted for sex,
age, education and marital status using a regression
model. In order to get hints about the existence of a
specific EMF symptom pattern, a cluster analysis was
performed to evaluate whether any symptom combination
was named more often than expected from chance.
Results
Symptoms of ill health and suspected EMF sources
Four hundred and twenty-nine individuals complet-
ed questionnaires between July 2001 and June 2002.
Of these, 394 complained about symptoms of ill
health. From the remaining 35 responders 7 claimed
that they were against mobile phone base stations in
residential areas and on schools, 6 were anxious
about a newly erected base station and expected
health disorders as a result of the new stations and
142 M. Rˆˆsli et al.
for 22 responders the reason for completing the
questionnaire was not clear. The analyses were
conducted with data from the 394 individuals who
were actually suffering from symptoms of ill health.
Overall, 114 different health complaints were
reported from the complainants. Those were sum-
marized into 47 different symptoms. The question-
naire allowed to state 5 symptoms at maximum. On
average 2.7 different symptoms of ill health were
listed per questionnaire. Figure 1 shows the number
of the 26 symptoms which were stated at least 6
times in decreasing order and classified by sex. Sleep
disorders (58%), headache (41%), nervousness or
distress (19%), fatigue (18%), and concentration
difficulties (16%) were most prevalent. The Pear-
son's chi-square test did not reveal a significant
difference between the symptom prevalence of men
and women (p 0.66).
The majority of the complainants stated that they
experienced symptoms of ill health at home. Occa-
sionally the symptoms occurred additionally at
other places (e. g. work place). Only 10 percent of
the complainants experienced the symptoms exclu-
sively outside the living place. Ninety percent of the
complainants reported that the symptoms appeared
after they had entered an ™exposure area∫ (e. g.
living place or the working place) and the symptoms
decreased after they had left it. The symptoms
appeared within a few minutes in 53 percent of the
complainants, within a few hours in 21 percent, and
within a few days in 17 percent. The decline in
symptoms after leaving the ™exposure area∫ was, on
average, similar but slightly slower.
Fifty-two percent of the complainants stated that
they suffered for less than 2 years from the described
symptoms, 71 percent for less than 3 years. Only 7
percent experienced the symptoms for longer than
10 years.
Most complainants declared that physical impair-
ment due to their symptoms was severe. Fifty-three
percent of them stated their physical impairment
with `very severe' or `severe', 35 percent reported
`medium' impairment. The mental impairment was
almost equally profound (41% severe and 33%
medium), whereas the social impairment was as-
sessed from none to medium by 76 percent of the
complainants. However, a few complainants stated
that they were not able to have a social live because
they were forced to avoid exposure situations.
Seventeen percent of the complainants stated that
they were at least partly incapacitated for work due
to their health complaints.
Fifty-six percent of the sample stated that they
were able to perceive electromagnetic fields. Most of
them specified a specific field type which they were
able to perceive such as radiation from mobile phone
Fig. 1. The 26 most frequently stated symptoms of ill health in decreasing order and classified by sex.
Symptoms of ill health ascribed to EMF 143
base stations, magnetic fields from power lines,
pulse modulated EMF, etc.
For a given choice of 11 EMF sources the
complainants had to estimate the utilization period
in minutes per day or distance to living place or work
place, respectively. Further they had to rate how sure
they were that their health problems were caused by
these sources. Seventy-six percent of the complai-
nants declared themselves as exposed to radiation
from mobile phone base stations either at the living
place or at the work place (Table 1). From those
exposed to mobile phone base stations 87 percent
reported that they were sure or rather sure that their
symptoms were due to this exposure. For other EMF
sources the proportion of worried persons was
considerably lower (Table 1). In the whole collective
(exposed and non exposed persons) 74 percent were
sure or rather sure that their symptoms were due to
exposure to mobile phone base stations (Figure 2).
Thus, some individuals associated their health
problems to mobile phone base station, although
they did not declare themselves as exposed at the
living or work place. The causality of other sources
than base stations was assessed considerably lower
in the collective (Figure 2). It was striking that the
complainants were very specific about the associa-
tions with different sources. Only 9 complainants
related their symptoms as sure or rather sure to all 11
sources. About a third of the afflicted population
quoted additional reasons for their symptoms. Of
the additional reasons, distress and environmental
factors (e.g. air pollution, noise, weather, amalgam)
were most commonly reported.
Demographic characteristics of the EHS sample
compared to the SHS sample
Table 2 compares the demographic characteristics
of the EHS complainants to subjects in the Swiss
Health Survey (SHS). In the EHS survey 57 percent
of the complainants were female. The average age of
the complainants was 51.0 years, which is statisti-
cally significantly older than in the SHS (mean:
46.1 y). The age group from 40 to 70 year was
particularly overrepresented in the EHS survey
collective compared to the SHS collective. Almost
two third of the complainants were married, which
was significantly more than in the SHS (52%). The
educational level of the EHS sample was signifi-
cantly higher than the one in the SHS. Differences in
marital status and educational level were not due to
the older age of the EHS sample. The proportion of
Swiss complainants was significantly higher in the
EHS survey than in the SHS.
In the SHS and EHS survey the same questions
about general health status were asked. Raw and
adjusted prevalences of several diseases were sig-
nificantly higher in the EHS collective than in the
SHS collective (Table 2).
Based on 4 standardised questions, sleep disorders
were classified as either `none', `medium' or `patho-
logical' (Abelin et al., 2000). Not surprisingly the
prevalence of sleep disorders was much higher in the
EHS sample than in the SHS. Similarly, the propor-
tion of complainants who suffered from intense
headache during the last 4 week was considerably
higher in the EHS collective than in the SHS
collective (Table 2).
In the short version of the Coping Inventory for
Stressful Situations (CISS) (Endler, 1999) coping
Table 1. Number of persons declaring themselves as exposed to a variety of EMF sources, median and 90%-percentile of the self estimated
distance or utilization period, as well as proportion of exposed persons ascribing their health problems to the respective exposure.
All ( n 394)
Number
of exposed
median 90%-percentile Ascribed symptoms
to the exposure source
Power lines 126 100 m 1000 m 61%
Train and tram lines 158 100 m 500 m 36%
Train/tram (use of) 87 20 min 94 min 36%
Transformers 74 100 m 695 m 53%
Broadcast transmitters 77 1000 m 10 km 44%
Mobile phone base stations 317 150 m 500 m 87%
Mobile phone 86 9 min 60 min 48%
Cordless phone 129 10 min 60 min 36%
TV set 323 60 min 180 min 18%
Computer 193 60 min 480 min 29%
Low voltage lighting 134 60 min 180 min 18%
144 M. Rˆˆsli et al.
strategies are classified into the three main scales
`task-', `emotion-' and `avoidance ± oriented' based
on 12 standardised questions resulting in a score
ranging from 4 to 20. The scale avoidance is divided
into the two subscale distraction and social diversion
(score range: 2 to 10). The EHS collective was more
task orientated and less emotional oriented than the
general Swiss population (Table 3). Avoiding stra-
tegies did not differ between the two collectives,
however, hypersensitive persons rather chose social
diversion (e.g. talking to a friend) than other
distractions (e.g. go for shopping).
Hints of possible problems
Such a survey cannot establish or negate a causal
association between symptoms of ill health and
EMF. However, in order to get hints of possible
problems the symptoms were analysed in three
different ways. First, we checked whether any
symptom patterns were named more often than
expected from chance, to elicit the presence of a
specific EMF symptom pattern. Cluster analysis did
not reveal specific symptoms appearing more often
together in the same person than expected by chance.
Thus, there was no indication that specific EMF
symptom patterns exist.
Second, we examined whether specific symptoms
were associated with specific EMF sources. For that,
the suspected EMF sources were grouped into three
categories according to the electromagnetic frequen-
cy range. Mobile communication and broadband
technique emits in the radio and microwave fre-
quency range. Computer and TV displays emit
mainly in the frequency range of a few kilohertz,
and use of electricity (power lines, transformer,
lighting, electrical devices) is related to emission in
the extremely low frequency range (ELF). We
analysed whether complainants ascribed their symp-
toms to EMF sources from one specific frequency
range or whether they suspected sources from
different frequency ranges (e.g. mobile phone and
power lines). One hundred and sixty-six (42%) of
the complainants rated the association to sources
from the group `communication technique' (radio-
and microwave) systematically higher than to other
sources. Only 8 persons (2%) related their symp-
toms predominantly to displays and 34 (9%) to
sources in the ELF range. About half of the
complainants did not favour sources from a sole
frequency range. The frequency of the 10 most often
stated symptoms did not differ statistically signifi-
cantly with respect to the ascribed causal source
group (c2,p0.21) (Table 4). There was a trend that
persons, who ascribed their symptoms to displays
Fig. 2. Suspected cause of symptoms in the whole collective.
Symptoms of ill health ascribed to EMF 145
suffered more often from headaches whereas in
others sleep disorders were the most prevalent.
Concentration difficulties and tinnitus were some-
what overrepresented in persons who related their
symptoms to communication technique sources.
Persons associating their symptoms to sources in
the ELF range complained more about nervousness
or distress than the others.
In order to investigate the symptoms with respect
to the exposure situation, the symptom patterns of
persons living closer than 100 m from ELF sources
(power lines, train or tram lines, transformers) were
compared with those of persons who did not live in
the vicinity of any EMF sources. We did not find
statistically significant differences in the frequency
of the 10 most often stated symptoms (c2:p0.24).
Similarly, we did not observe a different symptom
pattern for persons living close (<1 km) to broad-
cast transmitters (c2:p0.33) or close (<100 m) to
mobile phone base stations (c2:p0.28). Analogous
analyses were performed for users of mobile phones,
cordless phones and computers compared to persons
Table 2. Demographic characteristics and prevalence of various diseases in the survey among persons hypersensitive to electric and
magnetic fields (EHS) and the representative Swiss Health Survey (SHS) collectives in absolute numbers and in percent.
Group EHS collective
raw [n (%) ]
EHS collective
adj [n (%) ]
SHS collective
[n (%)]
Proportion test
[p value]
Total complainants 394 (100%) 394 (100%) 13004 (100%)
Sex
Male 169 (43%) ± 5760 (44%) 0.609
Female 223 (57%) ± 7244 (56%) 0.683
Age (years)
0 ± 19 21 (5%) ± 577 (4%) 0.368
20 ± 39 71 (18%) ± 5132 (39%) <0.001
40 ± 59 170 (43%) ± 3864 (30%) <0.001
>60 129 (33%) ± 3431 (26%) 0.006
Education (highest level)
No/little professional education 63 (16%) 63 (16%)ß3165 (24%) <0.001ß
Apprenticeship 164 (42%) 173 (44%)ß7681 (59%) <0.001ß
Higher education/University 150 (38%) 158 (40%)ß2158 (17%) <0.001ß
Marital status
Single 81 (21%) 112 (28%)ß3769 (29%) 0.850ß
Married 247 (63%) 230 (58%)ß6705 (52%) 0.005ß
Widowed/divorced/separated 61 (15%) 52 (13%)ß2524 (19%) <0.001ß
Nationality
Swiss 346 (88%) 348 (88%)ß10955 (84%) 0.009ß
Other nationalities 41 (10%) 46 (12%)ß2049 (16%) 0.015ß
General health status
Rheumatism 43 (10.9%) 37 (9.4%)≤581 (4.5%) 0.001≤
Bronchitis 23 (5.8%) 23 (5.8%)≤159 (1.2%) <0.001≤
High blood pressure 47 (11.9%) 40 (10.2%)≤1102 (8.5%) 0.236≤
Cancer 18 (4.6%) 16 (4.1%)≤110 (0.8%) 0.001≤
Allergy 32 (8.1%) 34 (8.6%)≤341 (2.6%) <0.001≤
Depression 26 (6.6%) 27 (6.9%)≤272 (2.1%) <0.001≤
Sleep disorder
None 105 (27%) 110 (28%)≤9280 (71%) <0.001≤
Medium 131 (33%) 129 (33%)≤3085 (24%) <0.001≤
Pathological 158 (40%) 155 (39%)≤638 (5%) <0.001≤
Headache
Not at all 80 (20%) 74 (19%)≤7736 (59%) <0.001≤
Somewhat 150 (38%) 146 (37%≤) 4124 (32%) 0.025≤
Intense 164 (42%) 174 (44%)≤1144 (9%) <0.001≤
ß adjusted for sex and age
≤ adjusted for sex, age, education, and marital status
Table 3. Mean scores of the different coping strategies in the EHS
and the SHS collectives.
EMF raw EMF adj.≤SHS p-Wert
Task 15.4 15.3 12.2 <0.001
Emotion 9.7 9.7 10.6 <0.001
Avoidance 9.9 10.1 9.8 0.196
Social diversion 6.0 6.1 5.5 <0.001
Other distractions 4.1 4.1 4.4 0.049
≤adjusted for sex, age, education, and marital status.
146 M. Rˆˆsli et al.
who did not use either of these devices. No
significant differences were observed (mobile phone
users: p 0.22; cordless phone users: p 0.19;
computer users: p 0.24). The symptom patterns
differed with respect to the persistency of the
symptoms (c2,p<0.01). In the category of short-
term symptoms (1 year) headache was more often
named than sleep disorders. In contrast, sleep
disorders were significantly more often persistent
(>4 year).
In the third type of `hint ± analysis', reported
symptoms in different demographic groups were
compared. Differences in the symptom patterns
were found with respect to the age of the complai-
nants (c2,p<0.01). Complainants in the age group
below forty complained more often about headache,
concentration difficulties and fatigue than older
ones. In contrast, complainants above 60 years
suffered considerably more from sleep disorders,
tinnitus and heart disease. Associations between
symptoms and marital status of the complainants
(c2,p0.01) as well as educational level (c2,p
0.01) were also observed. Headache was decreasing
with increasing educational level, in contrast ner-
vousness was more prevalent in persons with higher
educational level. No significant differences were
observed in the symptom patterns with respect to
gender (c2,p0.46), nationality (c2,p0.07) and
region (c2,p0.15) of the complainants. The
symptom pattern was independent of the ability to
perceive EMF (c2,p0.42).
Measures and consultations
Two hundred and eighty-one complainants (70%)
stated that they had at least one consultation due to
their health complaints. Family doctors and muni-
cipal authorities were contacted most often (Fig-
ure 3). Complainants consulted in average 3.0
different bodies. The complainants were asked to
state whether the consultations were satisfying or
not. Advise from public authorities and source
related companies were judged mostly as dissatisfy-
ing. Advises from self-help groups, therapists, build-
ing ecologists and others obtained a considerably
higher rating.
Two hundred and fifty-seven complainants (65%)
had taken measures to reduce their symptoms
(Figure 4). Among those, most (45%) stated that
they try to avoid exposure situations, if possible. For
instance, they changed the places of residence, the
office, or the place of the bed. Shielding of the
dwelling area with a curtain or net (25%), removing
indoor sources (22%) and drugs (22%) were quite
popular. For each step taken, the complainants were
asked to grade the efficiency from 1 (ineffective) to 6
(very useful). Highest rating received disconnecting
of the electricity (4.5), removing indoor sources
(4.3), avoiding exposure (4.3), and reconstruction
(4.2). In contrast, law complaints (1.1), change in
lifestyle (2.3), shielding of the dwelling, and com-
plementary medicine (3.1) obtained lowest rating.
From the 257 complainants who had taken steps to
reduce the symptoms, 25 percent stated that the
symptoms were unchanged, 37 percent felt a little
and 29 percent a substantial improvement after-
wards (the remaining gave no comment). When the
complainants were asked in an open question about
the best help for them they stated removing of a
specific EMF source (39%), a ban of EMF radiation
(13%), reduction of field levels (11%), information
and appreciation of their symptoms (9%), changing
living place (9%) and lower EMF standard limits
(7%).
Table 4. Frequency of the 10 most often stated symptoms with respect to the frequency range of the ascribed sources.
Symptoms of ill health ELF Display RF/MW unspecific
Total 34 (100%) 8 (100%) 166 (100%) 186 (100%)
Sleep disorder 19 (56%) 4 (50%) 100 (60%) 106 (57%)
Headache 12 (35%) 7 (88%) 74 (45%) 69 (37%)
Nervousness/distress 10 (29%) 2 (25%) 29 (17%) 32 (17%)
Fatigue 7 (21%) 2 (25%) 28 (17%) 32 (17%)
Concentration difficulties 4 (12%) 0 (0%) 38 (23%) 23 (12%)
Tinnitus 2 (6%) 1 (12%) 29 (17%) 22 (12%)
Dizziness 2 (6%) 1 (12%) 12 (7%) 30 (16%)
Limb pain 5 (15%) 2 (25%) 17 (10%) 20 (11%)
Heard disease 4 (12%) 1 (12%) 13 (8%) 24 (13%)
Arthropathy 4 (12%) 1 (12%) 7 (4%) 15 (8%)
Symptoms of ill health ascribed to EMF 147
Fig. 3. Proportion of complainants who consulted different bodies as well as satisfaction rating of these consultations.
Fig. 4. Proportion of complainants who took different measures to reduce the symptoms and grading of those measures from 1 (very
ineffective) to 6 (very effective). Measures are ordered in decreasing mean efficiency (figure at the end of the bar).
148 M. Rˆˆsli et al.
Discussion
The first aim of the survey was to examine the
experienced symptoms and suspected EMF sources.
In general, the reported symptom pattern is similar
to that of patients suffering from multiple chemical
sensitivity (MCS) or from sick building syndrome
(SBS) (Wiesm¸ller, 1998; Winder, 2002; Eberlein-
Kˆnig et al., 2002). However, sleep disorders were
considerably more prevalent in the EHS collective,
whereas irritative and allergic symptoms of the skin
and the respiratory tract are more common in MCS
and SBS patients.
Typically, the reported symptoms had been ex-
perienced relatively recently (71% suffered for less
than 3 years), what certainly correlates to the
development of the mobile communications. The
majority of the complainants stated that the symp-
toms were appearing when they enter the area of
exposure (e.g. their home) and were decreasing
when they had left it.
A second objective of the survey was to character-
ize the afflicted population and to compare it to a
representative sample of the Swiss population.
Compared to the Swiss population, complainants
were older, more often married and had a higher
educational level. The adjusted prevalence of the
most common diseases was significantly higher than
in the representative Swiss Health Survey collective.
The coping strategy of the complainants was on
average more task oriented and less emotional than
the one of the SHS collective. This may reflect the
method used to distribute the questionnaires. Per-
sons were asked to fill in a questionnaire after they
had become active and consulted a body such as
public authorities, building ecologists or telephone
companies, etc. The other possibility was that they
heard about it and asked directly at the Federal
Office of Public Health. Thus, it was most likely that
active persons had been addressed. More difficult to
interpret is the considerably lower emotional score
of the complainants. It might reflect the request of
the complainants to be taken more seriously. Over-
all, it was concluded that questions about coping
strategies may be biased and inadequate in this
specific setting.
A further aim of this survey was to obtain hints of
possible associations between reported symptoms
and EMF. The symptom pattern which was found in
this survey corresponds to the symptom pattern
which is associated to exposure to electromagnetic
fields in the public and scientific debate. Never-
theless, the result of this survey has to be interpreted
carefully with respect to causal associations. The
survey was not designed to establish or negate a
causal association. One might hypothesize that ELF
fields may cause symptoms different from those of
sources in the Megahertz range. However, we could
not find such differences. From the fact that no
symptom patterns were revealed with respect to
EMF sources it can be concluded that either EMF
acts very unspecifically or the symptom ascription is
significantly influenced by other causes. Public
debate may play an important role. In order to get
more insight into EHS further studies are needed.
This survey has not revealed an ™a priori' hypothesis
which should be examined. With respect to the
number of complainants sleep disorders and head-
ache should be investigated under blinded and
controlled exposure conditions. Such provocation
studies would be in particular adequate for the
majority of the complainants who stated that their
symptoms were appearing or disappearing within a
short time after they entered or left the area of
exposure.
The fourth aim of the present study was to get
suggestions of actions that should be taken to solve
the problems. The survey revealed that consultations
of public authorities showed to be very unsatisfac-
tory. It has to be taken into account that public
authorities may be consulted with other expecta-
tions than a self-help group or a building ecologist.
For instance, the removal of a mobile phone base
station is expected from the former but not from the
latter. Nevertheless, the results of this survey shows
that consultation of public authorities should be
improved. At least some of the complainants desire
more information and want to be taken more
seriously. A considerable proportion of complai-
nants' estimated distances to sources suggest that
measured field levels would be quite low. Never-
theless, the complainants considered themselves as
exposed. Thus, in many cases measurements might
contribute to a clarification. Individual consultation
of an environmental specialist and/or a medical
doctor may be helpful in many cases. However,
undoubtedly, in some cases help is limited as
inevitable conflicts of interest exists.
Acknowledgement. This study was funded by the Swiss
Federal Office of Public Health, Bern, Switzerland. Many
thanks to Sara Downs for careful proofreading of this
manuscript.
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