Bioelectromagnetics 28:137^151 (2007)

Development and Evaluation of theElectromagnetic Hypersensitivity

Questionnaire

Stacy Eltiti,1* DeniseWallace,1 Konstantina Zougkou,1 Riccardo Russo,1

Stephen Joseph,2 Paul Rasor,1 and Elaine Fox1

1University of Essex, Colchester, UnitedKingdom2University of Nottingham, Nottingham, UnitedKingdom

Electromagnetic hypersensitivity (EHS) syndrome is usually defined as a condition where an indi-vidual experiences adverse health effects that he or she believes is due to exposure to objects that emitelectromagnetic fields. The aimof this studywas to develop a questionnaire thatwould identify the keysymptoms associated with EHS and determine how often these symptoms occur in the generalpopulation of the United Kingdom. In the pilot study, an EHS questionnairewas developed and tested.In Study 1 the EHS questionnairewas revised and sent to a randomly selected sample of 20 000 people.Principal components analysis of the symptoms resulted in eight subscales: neurovegetative, skin,auditory, headache, cardiorespiratory, cold related, locomotor, and allergy related symptoms. Study 2established the validity of the questionnaire in that EHS individuals showed a higher severity ofsymptoms on all subscales compared to the control group. The two key results of this study were thedevelopment of a scale that provides an index of the type and intensity of symptoms commonlyexperienced by people believing themselves to be EHS and a screening tool that researchers can use topre-select the most sensitive individuals to take part in their research. Bioelectromagnetics 28:137–151, 2007. � 2006 Wiley-Liss, Inc.

Key words: electromagnetic fields; EHS Screening Tool; symptom subscales

INTRODUCTION

Electromagnetic hypersensitivity (EHS) is a rela-tively modern syndrome, which was first identified inthe 1980s [Hillert et al., 1999]. To date, there is noformal definition though it is usually accepted thatEHS is an environmental illness in which individualsexperience adverse health effects, which they believe tobe due to exposure to electric, electromagnetic, and/ormagnetic fields (EMFs) such as those produced bycomputers, mobile phones, power lines, etc. However,there is no generally accepted diagnostic criterion [e.g.,Bergqvist and Vogel, 1997; Hillert et al., 1999; Hillertet al., 2002; Levallois, 2002] and EHS is not commonlyrecognized as a medical illness. Therefore, EHS is aself-reported syndrome in which people report a varietyof symptoms that they believe are caused by EMFs.

The relationship between the symptoms experi-enced by EHS individuals and exposure to EMFs is yetto be demonstrated conclusively under experimentalconditions. In a review conducted by Rubin et al.[2005], 7 out of 31 blind or double-blind provocationexperiments resulted in some relationship betweenexposure to EMFs and symptoms. Of these, two studies

resulted in opposite effects (i.e., one showed enhancedmood while the other impaired mood), for two otherstudies the authors subsequently failed to replicate theiroriginal findings, and the results of three studies wereprobably due to statistical artefacts. In spite of this, theperception of EHS leads to wide-spread health prob-lems and more research is needed to test the hypothesisthat these symptoms are due to EMFs.

�2006Wiley-Liss, Inc.

——————This article contains supplementary material, available atwww.interscience.wiley.com/jpages/0197-8462/suppmat.

Grant sponsor: Mobile Telecommunication and Health ResearchProgram; Grant number: RUM 20.

*Correspondence to: Stacy Eltiti, Department of Psychology,University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.E-mail: seltiti@essex.ac.uk

Received for review 21 October 2005; Final revision received 30March 2006

DOI 10.1002/bem.20279Published online 29 September 2006 in Wiley InterScience(www.interscience.wiley.com).

Given that there is currently no medical criterionor reliable assessment tool for identifying EHSindividuals, researchers into bioelectromagnetics haveto rely on the individual’s self-diagnosis that the sym-ptoms they experience are caused by exposure to EMFs.Unfortunately, as noted in Rubin et al.’s review [2005],when experimenters are unable to find a relationshipbetween symptoms experienced and exposure to EMFs,their experiments are often criticized by action groupsand EHS individuals claiming that the most sensitiveindividuals were not tested. This is true even when theexperiments have taken into account other factors, suchas the duration and type of exposure matching thatreported by the EHS participants as situations in whichtheywould normally experience negative health effects.The implication is that if the researchers had tested themost sensitive individuals then a positive result wouldhave been found. At the moment there is no reliableself-report measure that allows an assessment of theseverity of EHS symptoms.

Part of the problem with developing selectioncriteria for EHS is that the degree of severity, the type ofsymptoms, and the type of object(s) that are believed tocause EHS symptoms often differ fromperson to person[e.g., Bergqvist and Vogel, 1997; Hietanen et al.,2002]. Symptoms range from headaches, memory loss,cardiovascular symptoms, digestive problems, pain/heating sensations in various parts of the body to skinrelated symptoms, such as skin rash and burning ortingling sensations. These symptomsmay be associatedwith a single object or a combination of two or moreobjects such as computers, mobile phones, electricalappliances, electrical wiring in the home, fluorescentlighting, microwave ovens, power lines, telecommuni-cation masts, televisions, and so on.

Hillert et al. [1999] have investigated the fre-quency of various symptoms reported by individualswith EHS. Two symptom indices were identified: skinsymptoms (redness, heat or burning sensations, tin-gling, smarting pain/soreness, swelling/blisters, and dryskin/mucosa) and neurovegetative symptoms (head-aches, fatigue, and difficulties in concentrating).Skin symptoms were significantly more frequent inthe EHS compared to the control group, aswasmyalgia,dizziness/vertigo, and nausea. There was no differencebetween the groups in terms of neurovegetativesymptoms. Moreover, no relationship was foundbetween their health survey and measures of mentalhealth or personality traits. In a further study, Hillertet al. [2002] conducted a factor analysis of EHSsymptoms and this produced two factors: neurovegeta-tive symptoms (fatigue, sense of heaviness in thehead, headache, nausea or dizziness, and difficulties toconcentrate) and eyes and airways (eye irritation, runny

or stuffy nose, impaired sense of smell, hoarse or drythroat, and coughing).

An obvious problem with the above symptoms asindicators of EHS is that they also occur naturally inthe general population. The key distinction, of course,is that EHS individuals attribute the cause of theirsymptoms to exposure to EMFs. Since so little iscurrently known about EHS, it is important to utilizeexploratory techniques in the general population usingmultivariate statistical analyses while at the same timeattempting to obtain the most parsimonious solution inorder to accurately portray the underlying structure ofEHS.

Hillert et al. [1999, 2002] have made a good startin determining differences between EHS individualsand the general population in the identification of threesymptom indices: skin, neurovegetative, and eyes andairways. However, the results are somewhat incon-sistent in that one study found no difference in neuro-vegetative symptoms between EHS and controls[Hillert et al., 1999], while a larger sample did reveala significant difference between EHS and controlgroups. In addition, their list of symptoms was limitedin range, focusing mainly on skin and head relatedsymptoms, and did not cover the wide range ofsymptoms often reported by the EHS individuals, suchas sleep disturbances, ringing or buzzing in the ears, andmemory difficulties. Given these limitations there isstill a need for a reliable classification system thatcan encompass the multidimensional nature of EHSsymptoms.

The symptoms commonly reported by EHS indi-viduals are all non-specific and to some degree occurnaturally in the general population. Theoretically, wepropose that the underlying structure of these non-specific symptoms is similar in EHS individuals andthe general population. There is a continuum in theseverity of these symptoms in the general population inwhich some individuals have no symptoms while othermay experience severe symptoms. It is not that EHSindividuals experience unique symptoms or evenunique symptom patterns, but that they experiencethese symptoms to a greater, sometimes even debilitat-ing degree, compared to most people in the generalpopulation.

The present study had three main objectives: (i) todevelop an electromagnetic hypersensitivity question-naire that could identify the symptom indices associ-ated with EHS, (ii) establish whether these indicesdiffer in terms of severity of symptoms between EHSindividuals and the general population, and (iii) basedon the results of the questionnaire, develop an EHSScreening Tool that could aid researchers in theidentification and recruitment of individuals with

138 Eltiti et al.

perceived EHS. In order to achieve these aims, a pilotstudy was conducted to develop and pilot items for anEHS questionnaire. In Study 1, the EHS subscales werefurther developed and tested on a large population-based sample. Reliability and validity of the EHSquestionnaire was tested in Study 2 through test-retestmeasures on a sample of EHS individuals and also bycomparing the results from EHS individuals to those inthe control sample obtained in Study 1.

PILOT STUDY: DEVELOPMENT OFQUESTIONNAIRE ITEMS

Given that the type of symptoms commonlyreported by EHS individuals are non-specific in natureand occur to some degree naturally in the generalpopulation, the focus of the pilot study was not only toidentify the key symptoms associated with EHS,but also to determine whether the severity of thesesymptoms is greater in EHS individuals than in thegeneral population. Since a key aspect of the defini-tion of EHS is that the individual believes his or hersymptoms are caused by exposure to EMFs, severalquestions were designed to allow the respondent tomake an association between their symptoms andexposure to various electrical objects that produceEMFs. A pilot study was conducted that developed andtested items for the EHS questionnaire.

Method

Construction of pilot EHS questionnaire. The pilotelectromagnetic hypersensitivity questionnaire hadthree main sections.

Biographical. The biographical questions obtainedinformation on age, gender, ethnicity, marital status,employment, and number of hours per week theindividual worked, volunteered, or spent studying.

Symptoms and causes. A 35-item symptom scale wasdeveloped by compiling symptoms published in theliterature [e.g., Bergqvist andVogel, 1997; Hillert et al.,1999, 2002; Flodin et al., 2000; Hietanen et al., 2002] aswell as symptoms reported by EHS individualsobtained through personal communication or consulta-tion with local action groups. For each symptom,participants were asked to rate whether they currentlysuffered from the symptom on a scale ranging from 0 to4: ‘not at all’(0), ‘a little bit’(1), ‘moderately’(2), ‘quitea bit’(3), and ‘a great deal’(4). Participants were askedwhether they believed their symptoms were associatedwith exposure to chemicals and a variety of EMFproducing objects. In separate questions, they were

asked to indicate whether they were sensitive tochemicals and EMFs. Questions about chemicals wereincluded since EHS is often reported to coincide withmultiple chemical sensitivity [e.g., Hillert et al., 2002;Levallois et al., 2002].

Participants were asked to indicate how far awaythey lived from a chemical factory, power lines, radio/television transmitters, and telecommunication mastsusing the following six-point scale: ‘less than one-quarter of a mile’(1), ‘one-quarter to one-half mile’(2),‘one-half to three-quarters mile’(3), ‘three-quarters to1 mile’(4), ‘more than 1 mile’(5), and ‘don’t know’(6).A ‘yes’ or ‘no’ question asked participants if they hadever experienced a severe electric shock and thefollowing four-point scale: ‘less than once a month’(1),‘less than once a week’(2), ‘more than once a week’(3),and ‘several times a day’(4), assessed how frequentlythey experienced static shocks. Finally, participantswere asked ‘are there any negative changes to yourhealth when you are around EMFs?’

General health. Current state of health was measuredby having participants place a cross (X) on a 12.8 cmline, which was anchored on one end with the label‘poor’ and on the other end ‘perfect.’ Participants wereasked using a ‘yes’ or ‘no’ question as to whether theysuffered from any chronic illness. In addition, partic-ipants completed the 12-item General Heath Question-naire [GHQ-12; Goldberg, 1978].

Participants. Questionnaires were mailed to 400 indi-viduals randomly selected from the Colchester phonebook of which 143 (35.8%) responded. The question-naire was also completed by a further 118 individualswho were either students or staff at the University ofEssex or obtained through personal contact (non-random sample). The total number of symptomsexperienced (t¼�0.4, P>.05) as well as the totalseverity of symptoms reported (Z¼�0.34, P>.05) didnot differ between the random and non-randomsamples. Therefore, the responses from both sampleswere combined forming the control group for allanalyses. Questionnaires were also completed by50 EHS individuals who were recruited through localaction groups, local support groups, or personal contact.

Results

Biographical. The average age for the control groupwas 52.0 years (SD¼ 18.8) while the EHS group had anaverage age of 52.5 years (SD¼ 12.4). Females madeup the majority of both the control (53%) and the EHSgroup (66%). There was a trend towards more femalesin the EHS compared to the control group (w2¼ 2.91,

EHSQuestionnaire 139

P¼.088; a¼ 0.05) with no differences in terms ofethnicity, marital status, type of employment, and timespent working, volunteering, or studying (Z< 1.5,P>.05). Unless otherwise indicated, non-parametricMann–WhitneyU-tests were performed to determine ifbetween-group differences were significant.

Symptoms

Step 1: principal components analysis. An explor-atory principal components analysis of the 35 symp-toms with direct oblimin rotation was carried out on thecontrol group responses only. Exploratory principalcomponents analysis was chosen because we wereinterested in the underlying pattern structure of thesymptoms and this was used to reduce the 35 symptomsinto a smaller number of symptom components. Directoblimin rotation, instead of the typical Varimaxrotation, was chosen from a theoretical perspective thatallows the components to be related to one another. Inother words, it makes sense that if an individual isexperiencing symptoms on one component (e.g., head-aches), the occurrence or severity of this symptommaybe related to another component (e.g., stress). A factorloading value of 0.4 was chosen to determine if an itemloaded onto any given component [Stevens, 1992]. Thisresulted in 11 componentswith eigenvalues greater thanone and accounted for 66.3% of the variance.

Step 2: forced factor solutions. Inspection of the screeplot showed only one component above a markedelbow. From a statistical point of view, therefore, themost parsimonious solution would be a one-factorsolution, since the first component accounted for 22%of the variance. However, EHS is a complex syndromeand little is currently known about the EHS symptompattern structure. Our aimwas to develop ameasure thatwill enable research into the specific aspects of EHS,and thus we deemed it more appropriate to exploreseveral multivariate solutions. In order to do this,several forced factor solutions with direct obliminrotation were sought. This was done with 10-, 9-, 8-, 7-,and 6-factor forced solutions.

The forced eight-factor solution resulted in thebest multivariate solution for the following fourreasons: it contained the least number of cross loadeditems, the highest number of items loading onto eachcomponent, the items that loaded onto each componentformed cohesive symptom categories, and it was able toaccount for 60.5% of the variance. On inspection of theitemswithin each component it was determined that thecomponentswere characterized as: (1) neurovegetative;(2) skin sensitivity; (3) skin sensations; (4) allergyrelated; (5) cold related; (6) symptoms of aging; (7)

cardiac related; and (8) headache. See Table 1 foreigenvalues, variance explained, and component load-ings. The following items loaded onto more than onecomponent: allergies, difficulty in concentration, facialprickling, impaired sense of smell, nausea, and pain/warmth in the head. Cardiac pains and sleep disturban-ces did not load onto any of the components. As part ofdata cleaning, three items were not included in theanalysis (digestive problems, dizziness, and runny/stuffy nose) because they each had a communalitiesvalue of less than 0.3.

Subscale construction. In order to obtain scores foreach of the eight components, subscale scores werecalculated by adding up the score for all the items thatloaded onto each component, except for cross loadeditems, such as difficulty in concentration, for everyrespondent. For example, the score for the neuro-vegetative subscale was created by summing anindividual’s score for anxiety, depression, fatigue, andstress. This means that the neurovegetative subscalecontained four items, skin sensitivity contained twoitems, skin sensations contained three items, allergyrelated contained two items, cold related contained fouritems, symptoms of aging contained five items, cardiacrelated contained two items, and headache containedthree items. A total symptom score was also calculatedby adding up the scores for the eight subscales. Therewas a significant difference between the control andEHS group for seven subscales and the total symptomscore (see Table 2 for descriptive statistics and Zvalues). Allergy related was the only subscale not toshow a significant difference. To avoid making Type 1errors Bonferroni corrections were applied whenevermultiple tests were conducted. See associated tables forcorrected alpha values.

Causes. The majority of control respondents did notbelieve there was a link between their symptoms andexposure to the specified range of environmentalfactors. However for the EHS group, a majority didbelieve there was some relationship between exposureto those objects (except detergents/soaps) and theoccurrence of their symptoms (See SupplementalTable S1 [www.interscience.wiley.com/jpages/0197-8462/suppmat]). The difference between the groupswas significant for all the objects except for detergents/soaps (Z¼�2.19, P¼.028).

There was a significant difference between thegroups with 41.4% of the control compared to 54.0% ofthe EHS group indicating that they were to some degreesensitive to chemicals (Z¼�3.25, P<.01). Whenasked ‘Are you sensitive to EMFs?’, 10.7% of thecontrol while 90.0% of the EHS group responded that

140 Eltiti et al.

they were sensitive to EMFs. The other 10.0% of theEHS group did not respond to this question. Notsurprisingly, this resulted in a significant differencebetween the two groups (Z¼�13.91, P<.01). Forthe EHS, but not the control group, there was asignificant correlation between the degree of sensitivityto chemicals and sensitivity to EMFs (r¼ 0.318,P<.05). For the question, ‘are there any negativechanges to your health when you are around EMFs?,’there was a significant difference with 89.3% of thecontrol group compared to 2.0% of the EHS groupresponding ‘not at all’ (Z¼�14.54, P<.01).

Interestingly, therewas not a significant differencebetween the control andEHSgroups in the distance theylived to both chemical factories (Z¼�1.24, P>.05)and power lines (Z¼�1.01, P>.05); however, therewas a significant difference for telecommunicationmasts (Z¼�5.44, P<.001) and a trend towards asignificant difference for radio/television transmitters(Z¼�2.23, P¼.026; alpha level set to 0.01 after

Bonferroni correction). This was due to a largerpercentage of EHS respondents indicating that theylived within 1 mile of a telecommunications mast and/or radio/television transmitters while almost half ofthe control group did not know how far away they livedfrom telecommunication masts (45.6%) or radio/television transmitters (47.1%).

This raises the question as to whether there is anactual difference or whether EHS individuals are moreaware that they are living in close proximity to radio/television transmitters and telecommunication masts.In order to determine how far respondents live fromtelecommunication masts, respondents’ post codeswere entered into Ofcom’s Sitefinder website, whichcontains the location of all telecommunication masts inthe United Kingdom, and individuals were dividedinto those who live within 100 m of a mast (near) andthose who live farther away (far). Chi-square analysisrevealed that there was no difference in the percentageof control (35.5%) and EHS (46.8%) respondents who

TABLE 1. Forced Eight-Factor Principal Component Analysis Eigenvalues, Percentage Variance Explained and Factor Loadingsfor the Pilot Study

Factor 1 2 3 4 5 6 7 8

Eigenvalues 7.2 2.5 2.0 1.9 1.7 1.5 1.4 1.3

Percentage 22.5 7.8 6.2 5.8 5.2 4.6 4.3 4.2

Allergies 0.43 0.56Anxiety 0.86Asthma 0.86Back pain 0.65Breathing difficulties 0.86Depression 0.77Difficulty in concentrating 0.50 0.37 �0.30Dry cough 0.70Eye problems 0.67Facial prickling 0.53 0.30Fatigue 0.48Headaches 0.64Heart palpitations 0.54Heaviness in the head 0.60High blood pressure 0.55Hoarse dry throat 0.77Impaired sense of smell 0.43 0.43Impaired sense of taste 0.73Memory difficulties 0.65Migraines 0.72Nausea 0.54 0.41Pain in joints 0.61Pain/warmth in head �0.44 0.52Pressure in the ear 0.51Skin burning sensation �0.77Skin irritation 0.63Skin numbness �0.76Skin rash 0.79Stress 0.82Tingling sensations �0.76

EHSQuestionnaire 141

lived within 100 m of a mast (w2¼ 2.11, P>.05). Itappears that EHS individuals do not live closer, but aremore aware of the location of telecommunicationmasts. Further analysis revealed no difference in theseverity of symptoms experienced by those living nearcompared to those living farther away from tele-communication mast (Z <�1.0, P<.05).

There was no significant difference between thecontrol (25.7%) andEHS (34.0%) groups in terms of thefrequency of individuals who had experienced a severeelectric shock (w2¼ 1.58, P>.05). However, there wasa significant difference between the groups in theoccurrence of static shocks (Z¼�3.20, P<.01). Forthe control group 61.7% experienced static shocks ‘lessthan once a month,’ 16.9% ‘less than once a week,’13.0% ‘more than once a week,’ and 5.0% experiencedstatic shocks ‘several times a day.’ In comparison, theEHS group responded that 40.0% experienced staticshocks ‘less than once amonth,’ 16.0% ‘less than once aweek,’ 8.0% ‘more than once a week,’ and 26.0%experienced static shocks ‘several times a day.’

General health. In terms of general health there was asignificant difference between the control and EHSgroups. For the question in which the respondents wereinstructed to indicate their current state of health(poor—perfect), the control group responded with

significantly better current health (M¼ 8.90, SD¼2.71) than the EHS group (M¼ 5.54, SD¼ 3.80;t¼ 6.88, P<.01). There was also a significant differ-ence between the groups on the GHQ-12 (t¼�3.14,P<.01)with theEHSgroup scoring higher (M¼ 15.19,SD¼ 5.95) than the control group (M¼ 10.99,SD¼ 4.99) indicating poorer general mental health. Inaddition, a bivariate correlation between the GHQ-12and the total symptom score revealed a significantcorrelation for both the control (r¼ .57, P<.01) andEHS group (r¼ .87, P<.01). Lastly, there was asignificant difference between the groups in terms ofchronic illness (w2¼ 8.39, P<.01) in which 14.6% ofthe controls compared to 32.0% of the EHS group had achronic illness.

Discussion

The results indicated that EHS individualsexperience a greater severity of symptoms, suffer frompoorer general health, and attribute the cause of theirsymptoms to exposure to objects emitting EMFs andchemicals to a greater extent than most members of thegeneral public. Using exploratory principle compo-nents analysis, the symptoms were classified into eightkey components. It was observed, however, that five outof the eight would contain less than four items if thecross loaded items were removed from the factor

TABLE 2. Descriptives and Z-scores for the Subscales and Total Symptom Score for the Control and EHS Respondents in thePilot and Studies 1 and 2

Subscale

Control EHSa

ZbMean Median SD Mean Median SD

Pilot StudyNeurovegetative 3.2 3.0 2.9 7.2 6.0 4.5 �5.7**Skin sensitivity 0.8 0.0 1.4 3.0 2.0 7.8 �5.5**Skin sensations 0.5 0.0 1.4 4.3 3.0 3.9 �8.5**Allergy related 0.6 0.0 1.4 1.0 0.0 1.8 �1.8Cold related 1.1 0.0 1.8 4.0 3.0 3.9 �5.6**Symptoms of aging 3.5 3.0 2.8 7.0 8.0 4.4 �4.8**Cardiac related 0.7 0.0 1.1 1.9 1.5 1.8 �4.9**Headache 1.3 1.0 1.7 4.5 4.0 3.2 �6.9**Total symptom score 11.2 9.0 8.7 31.2 31.0 20.4 �6.0**

Studies 1 and 2Neurovegetative 6.6 5.0 6.3 15.4 16.0 9.2 �9.0**Skin 2.1 1.0 3.4 6.2 3.5 6.7 �7.3**Auditory 1.1 0.0 2.0 5.1 3.0 5.0 �9.3**Headache 2.9 2.0 3.8 8.4 7.0 6.2 �9.7**Cardiorespiratory 1.0 0.0 1.8 2.7 1.5 3.0 �7.4**Cold related 1.7 1.0 2.2 3.2 2.0 3.3 �4.6**Locomotor 3.4 3.0 3.1 5.2 5.0 4.0 �4.3**Allergy related 0.7 0.0 1.0 1.2 1.0 1.4 �3.8**Total symptom score 19.4 15.0 16.4 47.4 45.0 27.9 �10.1**

**P<.001; EHS, electromagnetic hypersensitivity.aThe EHS sample in the lower half of the table refers to respondents in Study 2.bMann–Whitney U-tests, alpha level¼ 0.005.

142 Eltiti et al.

structure. Components should have at least four itemswith a loading of 0.6 in order to be reliable unless thereis a larger sample size, that is, at least 300 [Stevens,1992]. In addition, many EHS respondents reportedsymptoms that were not part of the original list of 35symptoms. Given the small number of items loadingonto each component as well as the discovery ofadditional self-reported EHS symptoms, it was clearthat further development of the scale was needed inorder to determine the reliability of the initial eightcomponents and gain a more comprehensive picture ofthe underlying structure of EHS.

STUDY 1: DEVELOPMENT OF EHS SUBSCALES

The aim of Study 1 was to further develop and testthe reliability of the eight symptom subscales identifiedin the pilot study on a large random population sample.Twenty-two new symptoms were included (e.g., badtaste in themouth, blurry vision, foggy thinking, ringingand/or buzzing in the ear, and skin redness). Theseadditional symptoms were obtained by examining EHSresponses in the pilot study to the open question ‘if youare sensitive to electromagnetic fields, what electricalequipment . . . bothers you the most and what are thesymptoms that you experiencewhen you are exposed tothe electromagnetic field?’ and extracting any symp-toms that were not part of the original list of symptoms.This resulted in a 57-item questionnaire. In addition,three new general health questions were includeddealing with: current well being, general health, andsleep quality, while the questions relating to chemicalsensitivity and how far an individual lived from variousenvironmental objects were removed. See on-lineSupplemental Table S2 (www.interscience.wiley.com/jpages/0197-8462/suppmat) for a complete copy of thequestionnaire.

Method

Participants. Questionnaires were sent to 20 000individuals randomly selected from the edited electoralroll who lived within a 20 mile radius of Colchester.From this population 4431 (22.2%) were returned. Ofthe questionnaires returned, 3633 (18.2%) were com-pleted and 798 (4.0%) were uncompleted for variousreasons; in themajority of cases the individual no longerresided at that address (709). Although measures weretaken to encourage compliance, the response rate to ourstudy was low, a problem not uncommon with postalsurveys [Newell et al., 2004] and not limited to aparticular subject matter [e.g., Angus et al., 2003;Jacoby and Jacoby, 2004]. The respondents had anaverage age of 52.8 years (SD¼ 14.30) with 2009(55.3%) being female and 1624 (44.7%) being male.

The majority of the group were White British (97.1%),married (82.5%), employed (62.5%), and the largestpercentage of respondents indicated that they worked,volunteered, or studied 0 hours per week (26.0%).

Results

Symptoms. The methods employed for the principalcomponents analysis of the 57 symptoms was the sameas that used in the pilot study, which resulted in 12components and accounted for 56.6% of the totalvariance. Similar to the pilot study, alternative multi-variate forced factor solutions were sought. The forcedeight-factor solution proved to be the best solution withwhich to develop amultifactorialmeasure because eachcomponent except one contained at least four items,while at the same time having the least number of crossloaded items, and still being able to account for morethan 50% of the variance. In addition, the items thatloaded onto each component formed theoreticallycohesive symptom categories.

Forced eight-factor solution. The eight-factor forcedsolution accounted for 52.8% of the variance. Eigen-values, variance explained, and item loadings are listedin Table 3. On inspection of the items within eachcomponent, it was determined that the componentswere characterized as (1) neurovegetative; (2) skin; (3)auditory; (4) headache; (5) cardiorespiratory; (6) coldrelated; (7) locomotor; and (8) allergy related.As part ofthe data cleaning any symptoms with a commonalityextraction less than 0.3 were excluded, which resultedin the exclusion of the following eight symptoms: badtaste in the mouth, blisters on the skin, blurry vision,cold sweat, digestive problems, eye problems, facialprickling, and high blood pressure.

Hillert et al. [2002] split their population sampleinto a control group and EHS group based on whetherthe individual said they were hypersensitive or allergicto electric or magnetic fields. They conducted aprincipal component analysis on the control groupand then replicated the factor structure on the EHSgroup. In the EHS questionnaire, question 67 ‘Are yousensitive to EMFs?’ is similar to that of Hillert et al. andwas used to extract a large scale EHS group in order todetermine if the above forced eight-factor solutioncould be replicated in a large sample EHS group. Therewere 698 individuals who made a positive response tothis question and their symptom scores were subjectedto a forced eight-factor solution with direct obliminrotation. The results for this EHS group were similar tothose of the general population with most items loadingtogether on the same component. The only substantial

EHSQuestionnaire 143

difference was component eight ‘allergy relatedsymptoms’ in which allergies and asthma no longerloaded onto this component, but instead nausea (�0.49)and sickness (�0.54) formed the items for thiscomponent. See Table 4 for item loadings for the eightcomponents for both the general population and EHSsubgroup.

Subscale construction. Just as in the pilot study, theeight subscales were calculated by adding up each

symptom that loaded on that component. Sleepdisturbances and asthma cross loaded onto twocomponents; therefore, they were not included in thesubscale scores. This resulted in the neurovegetativesubscale containing nine items, skin containing sevenitems, auditory containing four items, headache con-taining six items, cardiorespiratory containing fouritems, cold related containing four items, locomotorcontainingfive items, and allergy related containing oneitem. See Table 2 for descriptive statistics.

TABLE 3. Forced 8-Factor Principal Component Analysis Eigenvalues, Percentage Variance Explained and Factor Loadings forStudy 1

Factor 1 2 3 4 5 6 7 8

Eigenvalue 12.75 2.89 2.16 2.03 1.76 1.60 1.40 1.29

Percentage 26.0 5.9 4.4 4.1 3.6 3.3 2.9 2.6

Allergies 0.48Anxiety 0.73Asthma 0.43 0.41Back pain �0.61Breathing difficulties 0.63Cardiac pains 0.84Chest pains 0.77Depression 0.73Difficulty in concentrating 0.83Difficulty in focusing attention 0.79Dry cough 0.41Dry skin 0.48Dull headache �0.74Exhaustion 0.53Fatigue 0.54Foggy thinking 0.66Headaches �0.84Heart palpitations 0.41Heaviness in the head �0.53Impaired sense of smell 0.77Impaired sense of taste 0.76Memory difficulties 0.59Migraines �0.81Muscle tension �0.47Muscle weakness �0.52Pain in the ear 0.74Pain in joints �0.71Pain/Soreness of the skin 0.72Pain/Warmth in head �0.44Pressure in the ear 0.77Ringing/Buzzing in the ear 0.62Runny or stuffy nose 0.43Sharp pain in the head �0.63Skin burning sensation 0.57Skin irritation 0.81Skin rash 0.85Skin redness 0.86Skin swelling 0.59Sleep disturbances 0.40 �0.33Stress 0.69Warmth in the ear 0.66

144 Eltiti et al.

Component 1 accounted for half of the totalexplained variance. From a statistical perspective itwould follow that all the items could be accounted forby a single component solution. Therefore, a forcedone-factor solution with direct oblimin rotation wasconducted to determine if, ultimately, the eightsubscales could be condensed into one. This resultedin all eight subscales loading onto one component withan eigenvalue of 3.43,which accounted for 42.9%of thetotal variance with the following factor loadings:neurovegetative (0.77), skin (0.62), auditory (0.63),headache (0.72), cardiorespiratory (0.64), cold related(0.67), locomotor (0.72), and allergy related (0.41).Since all eight subscales can be reduced to onecomponent it is possible to combine the subscale scoresinto a single or total symptom score.

Causes. Similar to the pilot study, the majority of thecontrol respondents indicated that they did not believethat there was a link between the occurrence ofsymptoms (1–57) and exposure to various objects thatproduce EMFs. However, the pattern fluctuateddepending on the type of object. See Table 5 for fulldetails of frequency of responses by objects.

The majority of respondents indicated that theywere ‘not at all’ sensitive to EMFs (80.3%) nor did theyexperience any negative changes to their health whenaround EMFs (81.8%). In response to the open question68 ‘if you are sensitive to EMFs, what electricalequipment . . .bothers you the most . . .,’ 5.2% indicatedthat they were sensitive to computers, 4.2% to mobilephones, 1.9% to power lines, 1.6% to televisions, 1.2%to fluorescent lighting, 0.6% to microwave ovens, 0.4%to electrical appliances, 0.3% to radio/television trans-mitters, and 0.3% to telecommunication masts.

A minority of 32.6% indicated that they hadexperienced a severe electric shock while the occur-rence of static shocks was more diverse with 25.5%indicating that they never experience static shocks,34.4% ‘less than once amonth,’ 17.7% ‘less than once aweek,’ 17.0% ‘more than once a week,’ and 5.0%‘several times a day.’

General health. Most of the respondents indicatedthat they believed their well being and general healthwas moderately good or better and that they feltrefreshed after a night’s sleep. In addition, a vastmajority of the sample (80.3%) did not suffer from anychronic illness.

Discussion

Comparable to the results of the pilot study, thebest multivariate solution for the exploratory principle

TABLE 4. Factor Loadings for the General Population andEHS Group Identified Using Question 67 for the Forced Eight-Factor Solution in Study 1

Symptom Group

Neurovegetative General population EHSa

Anxiety 0.73 0.63Depression 0.73 0.67Difficulty in concentrating 0.83 0.86Difficulty in focusing attention 0.79 0.78Exhaustion 0.53 0.52Fatigue 0.54 0.49Foggy thinking 0.66 0.69Memory difficulties 0.59 0.59Sleep disturbances 0.40 0.33Stress 0.69 0.57

Skin

Dry skin 0.48 0.51Pain/Soreness on the skin 0.72 0.74Skin burning sensation 0.57 0.59Skin irritation 0.81 0.80Skin rash 0.85 0.82Skin redness 0.86 0.85Skin swelling 0.59 0.66

Auditory

Pain in the ear 0.74 0.67Pressure in the ear 0.77 0.74Ringing/Buzzing in the ear 0.62 0.59Warmth in the ear 0.66 0.70

Headache

Dull headache �0.74 0.77Headaches �0.84 0.87Heaviness in the head �0.53 0.56Migraines �0.81 0.82Pain/Warmth in head �0.44 0.37Sharp Pain in the head �0.63 0.57

Cardiorespiratory

Asthma 0.43 0.41Breathing difficulties 0.63 0.67Cardiac pains 0.84 0.76Chest pains 0.77 0.75Heart palpitations 0.41 0.31

Cold related

Dry Cough 0.41 0.49Impaired sense of smell 0.77 0.68Impaired sense of taste 0.76 0.63Runny or stuffy nose 0.43 0.42

Locomotor

Back pain �0.61 �0.64Muscle tension �0.47 �0.43Muscle weakness �0.52 �0.48Pain in joints �0.71 �0.73Sleep disturbances �0.33 �0.36

Allergy related

Allergies 0.48 0.34Asthma 0.41 0.21

aEHS group represents the 698 individuals identified using question67.

EHSQuestionnaire 145

components analysis of the 57 symptoms was aforced eight-factor solution. The eight subscales were:neurovegetative, skin, auditory, headache, cardiores-piratory, cold related, locomotor, and allergy related.Ultimately these items could be reduced to a singlecomponent solution resulting in a total symptom score.

Now that we had a better understanding of theunderlying structure of these symptoms it was impor-tant to determine whether, in terms of EHS, the scale isboth valid and reliable.

STUDY 2: RELIABILITY AND VALIDITYOF EHS QUESTIONNAIRE

In order to establish the validity and reliability, theEHS questionnaire was completed by individuals whoself-reported being sensitive to EMFs. If the symptomscales are valid, then EHS respondents should experi-ence a greater severity of these symptoms compared to

the normative data obtained in Study 1. The test-retestmethod was utilized to determine whether an individ-ual’s symptom score remained relatively constant overdifferent periods of time thereby giving us a measure-ment of reliability.

Method

Participants. The EHS questionnaire was completedby 88EHS individualswhowere recruited through localaction groups, local support groups, or personal contactand had not participated in the pilot study. The averageage was 48.7 years (SD¼ 14.0) with 47 (53.4%) beingfemale. Thirty-two of these respondents took part in theretest. The retest questionnaires were completedbetween 1 and 8months after the original questionnaire.The responses were divided into two groups: short term(1–3 months) and long term (4–8 months). This wasdone in order to determine the short term and long term

TABLE 5. Frequency of Responses and Mann–Whitney U-Tests for Control and EHS Respondents by Objects the Emit EMFsfor Studies 1 and 2

Objects

Not at all A little bit Moderately Quite a bit A great deal

ZaN (%) N (%) N (%) N (%) N (%)

ComputersControl 2357 (64.9%) 794 (21.9%) 286 (7.9%) 124 (3.4%) 44 (1.2%)EHS 27 (30.7%) 19 (21.6%) 10 (11.4%) 12 (13.6%) 18 (20.5%) �8.39**

Electrical appliancesControl 3111 (85.6%) 351 (9.7%) 98 (2.7%) 36 (1.0%) 8 (0.2%)EHS 42 (47.7%) 23 (26.1%) 4 (4.5%) 10 (11.4%) 9 (10.2%) �10.22**

Fluorescent lightingControl 2393 (65.9%) 762 (21.0%) 275 (7.6%) 120 (3.3%) 55 (1.5%)EHS 38 (43.2%) 12 (13.6%) 11 (12.5%) 8 (9.1%) 18 (20.5%) �6.10**

Microwave ovensControl 2938 (80.9%) 457 (12.6%) 138 (3.8%) 48 (1.3%) 19 (0.5%)EHS 46 (52.3%) 17 (19.3%) 8 (9.1%) 4 (4.5%) 12 (13.6%) �7.30**

Mobile phonesControl 2459 (67.7%) 640 (17.6%) 284 (7.8%) 150 (4.1%) 66 (1.8%)EHS 13 (14.8%) 13 (14.8%) 16 (18.2%) 13 (14.8%) 32 (36.4%) �12.84**

Power linesControl 2688 (74.0%) 458 (12.6%) 244 (6.7%) 143 (3.9%) 61 (1.7%)EHS 33 (37.5%) 11 (12.5%) 16 (18.2%) 8 (9.1%) 18 (20.5%) �8.79**

Radio/TelevisiontransmittersControl 2889 (79.5%) 402 (11.1%) 186 (5.1%) 91 (2.5%) 28 (0.8%)EHS 41 (46.6%) 14 (15.9%) 7 (8.0%) 8 (9.1%) 11 (12.5%) �8.36**

TelecommunicationmastsControl 2728 (75.1%) 452 (12.4%) 234 (6.4%) 127 (3.5%) 55 (1.5%)EHS 17 (19.3%) 9 (10.2%) 10 (11.4%) 11 (12.5%) 36 (40.9%) �13.89**

TelevisionsControl 2796 (77.0%) 584 (16.1%) 162 (4.5%) 41 (1.1%) 18 (0.5%)EHS 37 (42.0%) 25 (28.4%) 8 (9.1%) 8 (9.1%) 10 (11.4%) �8.29**

**P<.001; EHS, electromagnetic hypersensitivity; EMF, electromagnetic fields.aMann–Whitney U-tests; alpha level¼ 0.006.

146 Eltiti et al.

reliability of the questionnaire. In addition, six non-EHS respondents who were either family members orfriends of the EHS respondent also took part in the test-retest, all of whom completed the retest 1–3 monthsafter the initial questionnaire. The majority of respond-ents were White British (84.1%), married (54.5%),employed (55.6%), and the largest percentage worked,volunteered, or studied 31–40 h per week (22.7%).

Results

Validity. Validity was determined by comparing theEHS responses with those from the control groupobtained in Study 1. The EHS group had a greaterseverity of symptoms than the control group for all eightsubscales and for the total symptom score (see Table 2for descriptive statistics and Mann–Whitney U-tests).A majority of the EHS respondents indicated that theybelieved there was a link between the occurrence oftheir symptoms (1–57) and exposure to various objectsthat produce EMF, except for microwave ovens. Therewas a significant difference between the groups for allobjects in that more EHS respondents believed therewas a relationship between the occurrence of theirsymptoms and exposure to those objects compared tothe control group (see Table 5 for full details).

Importantly, a larger proportion of EHS (90.9%)than control respondents (17.5%) indicated that theywere to some degree sensitive to EMFs (Z¼�18.2,P<.001). Additionally, more EHS (92.1%) comparedto control participants (16.0%) reported negativechanges to their health when around EMFs(Z¼�20.3, P<.001). There was a tendency for moreEHS respondents (42.0%) compared to the controlgroup (32.9%) to have experienced a severe electricshock (w2¼ 3.6, P¼.06) and the occurrence of staticshocks was higher among the EHS than the controlgroup, which resulted in a significance difference(Z¼�3.2, P<.001).

Lastly, there was a significant difference betweenthe control and EHS samples with the control groupreporting higher levels of current state of well being(Median: control¼ 3, EHS¼ 2), good health (Median:control¼ 3, EHS¼ 2), and sleep (Median: control¼ 2,EHS¼ 1; all Z0s>�4.5, P0s< .001). A larger percent-age of EHS (37.5%) compared to control (17.9%)respondents suffered from a chronic illness (w2¼ 20.9,P<.01).

Reliability. The internal consistency reliability amongthe retest symptoms were calculated using Cronbachalpha for the total symptom score and symptomssubscales, except allergy related.According toNunnaly[1978], a Cronbach alpha of 0.70 or higher is considered

acceptable or satisfactory. Additionally, test–retestcorrelations were calculated for the following items:eight symptoms subscales, total symptom score,questions regarding the relationship between symptomsand various EMF-producing objects, sensitive to EMF,negative health changes around EMF, and the threegeneral health questions. See Table 6 for a complete listof Cronbach alphas and correlation coefficients. Over-all, both the internal consistency and test–retestcorrelations were good for most of the above measures.The cardiorespiratory subscale resulted in a low internalconsistency for both the short term (a¼ 0.52) and longtermgroup (a¼ 0.44). The auditory subscale resulted inlow internal consistency for the short term group(a¼ 0.56), while the locomotor subscale resulted in lowinternal consistency for the long term group (a¼ 0.63).The test–retest correlation for the neurovegetativesubscale was not significant for the long term group(r¼ 0.37). In addition, the test-retest reliability regard-ing the series of questions in which respondentsindicated whether they believed there was a linkbetween their symptoms and exposure to differentobjects waswidely varied with higher values among thelong term group (r¼ 0.50–0.87) than the short termgroup (r¼ 0.28–0.74).

Discussion

The validity of the EHS questionnaire wasestablished in that the EHS group suffered a greaterseverity of symptoms than the control group for the totalsymptom score and for all eight subscales. More EHSindividuals than controls responded positively toquestions that asked them to indicate if they believedtherewas a relationship between the occurrence of theirsymptoms and exposure to various objects, whetherthey believed theywere sensitive to EMFs, and that theyexperienced negative changes to their health whenexposed to EMFs.

The reliability of the EHS questionnaire wasdemonstrated in the test-retest analysis. Overall, goodinternal consistency and test-retest reliability wasobtained for the subscales and the total symptom score.In addition, the twomain questions regarding the degreeof sensitivity to EMFs also resulted in a high level ofreliability. The reliability measures were stronger forthe short term group than the long term group.Responses in the long term group showed that theseverity of symptoms and sensitive to EMFs decreasedslightly between the time of test and retest. What isunclear is the reason behind this decrease. Throughpersonal communication with EHS sufferers, we knowthatmany of themhave adopted new behaviors aimed atprotecting themselves from exposure to EMFs or

EHSQuestionnaire 147

reducing the severity of symptoms experienced. Forexample, the respondent no longer uses amobile phone,spends fewer hours on the computer, eats organic food,or takes homeopathic remedies, which, in some cases,may decrease the severity of symptoms experiencedand thereby reduce the reliability of the questionnaire.Another possible explanation is that we are seeing aregression towards the mean.

GENERAL DISCUSSION

Five components were the same for both the pilotstudy and Study 1: neurovegetative, skin, allergyrelated, cold related, and headache. In Study 1, thetwo components: skin sensitivity and skin sensationscombined to form only one component: skin. Symp-toms of aging became locomotor and cardiac relatedbecame cardiorespiratory in Study 1. One newcomponent, auditory, emerged in Study 1. This was

primarily due to the inclusion of more ear relatedsymptoms. The addition of 22 symptoms in Study 1boosted the number of items that loaded onto eachcomponent with only one component (allergy related)having less than four items. There was a significantdifference between the control and EHS groups for allsubscales, except allergy related in the pilot study. TheEHS consistently reported a greater severity ofsymptoms in comparison to the control group.

Based on the precedent set by Hillert et al. [2002],we used question 67 to select fromour population groupin Study 1 individuals who to some extent reportedbeing sensitive to EMFs. A forced eight-factor solutionwas then performed on this subsample, which resultedin a similar pattern of symptoms to that obtained for thegeneral population. This result supports the theoreticalassumption that the symptom structure is similar forboth groups. However, given that only one questionwasused to identify EHS individuals we are reluctant to

TABLE 6. Cronbach Alpha’s and Spearman Correlations for Short Term and Long TermResponse Groups for Study 2

Questionnaire items

Short term (1–3months) Long term (4–8months)

aa rb a r

SubscalesNeurovegetative 0.93 0.95** 0.90 0.37Skin 0.94 0.89** 0.73 0.88**Auditory 0.56 0.71** 0.85 0.91**Headache 0.86 0.86** 0.88 0.65**Cardiorespiratory 0.52 0.85** 0.44 0.67**Cold related 0.70 0.62** 0.88 0.76**Locomotor 0.77 0.86** 0.63 0.76**Allergy related 0.79** 0.81**Total symptom score 0.82 0.91** 0.81 0.70**

EMF objectsComputers 0.59** 0.81**Electrical appliances 0.69** 0.87**Fluorescent lighting 0.28 0.83**Microwave ovens 0.38 0.55*Mobile phones 0.65** 0.50Power lines 0.41 0.82**Radio/Television transmitters 0.41 0.72**Telecommunication masts 0.74** 0.83**Television 0.66** 0.81**

EHS questionsSensitive to EMF 0.82** 0.52Negative health around EMF 0.94** 0.53*

General healthWell being 0.65** 0.73**Good health 0.66** 0.76**Sleep 0.78** 0.61*

*P¼.05(two-tailed).**P¼.01(two-tailed).aa¼Cronbach alpha.bSpearman correlation.

148 Eltiti et al.

draw any firm conclusions based solely on this analysis.Do these randomly selected individuals provide arepresentative sample of those who self-report beingEHS as in Study 2? Unfortunately, reliable principalcomponents analysis could not be conducted on theEHS group in Study 2 due to the small sample size[Tabachnick and Fidell, 1996]. If, in future research,larger self-reported samples of EHS individuals couldbe obtained, that is, at least 500 it would be beneficial toreplicate the forced eight-factor solution to determine ifthere are any differences in the underlying pattern ofsymptoms between the groups.

A significantly larger proportion of EHS respond-ents suffered from a chronic illness compared to thecontrol groups in both the pilot study and Study 1. Avariety of chronic illnesseswere listed, with some of themore common responses from Study 2 being: chronicfatigue syndrome (9.1%), diabetes (8.0%), back/spine/joint diseases (6.8%), and deficient/overactive thyroid(4.5%). From our study, it is impossible to determinewhat relationship, if any, there is between EHS andother chronic illnesses, such as chronic fatiguesyndrome; however, it does merit further investigationgiven the large number of EHS individuals who alsosuffer from chronic illnesses.

It has been suggested that a severe electric shockmay be a contributing factor to some individualsbecoming sensitive to EMF (Anne Silk, personalcommunication). However, in the pilot study, therewas no significant difference between the control(32.9%) and EHS (39.1%) groups, although there wasa trend towards a significant difference in Study 2, inthat 42.0% of EHS compared to 32.9% of controlrespondents (Study 1) had suffered a severe electricshock. For both studies, EHS respondents experiencedstatic shocks significantly more often than the controlrespondents. One possible explanation is that perhapsEHS individuals are more self-aware than controlindividuals and this awareness leads to a greaterreporting of static shocks. It would be interesting todetermine if the occurrence of static shocks were morefrequent before or after the individual became sensitiveto EMFs.

EHS Criterion

Two key aspects of the definition of EHS are thatthe individual experiences symptoms and he or shebelieves that these symptoms are the result of exposureto EMFs. Therefore, the selection criteria for identify-ing EHS must take into account both the severity andattributed cause(s) of those symptoms. In order todetermine the severity of a respondent’s symptoms, thetotal symptom score provides the best overall measure.

From the control data obtained in Study 1, itwas evidentthat these symptoms naturally occur to varying degreesin the general population. In other words, there was acontinuum of symptom severity ranging from individ-uals who experience mild or no symptoms to thosewithmoderate symptoms to those with severe symptoms.The typical way in which distributions are normallydivided into different groups is to use the mean plus orminus one standard deviation.However, the distributionof total symptom scores in Study 1 was skewed to thelower endwith a large proportion of respondents havingno or mild symptoms. Therefore, we divided thedistribution into three symptom severity groups usingquartiles to approximate a normal distribution. Thebottom 25th percentile (total symptom score� 7)represented no or mild symptoms, the 25th to 75thpercentile (total symptom score 8–25) representedmoderate symptoms, and the 75th percentile and over(total symptom score� 26) represented severe symp-toms. Using these cutoff points, 1 (1.1%) of the EHSrespondents (from Study 2) was classified as havingmild symptoms, 22 (25.0%) with moderate symptoms,and 65 (73.9%) with severe symptoms.

The best way to assess if individuals believe theirsymptoms are caused by EMFs is to see how theyrespond to question 68 ‘if you are sensitive to EMFs,what electrical equipment . . . bothers you the most andwhat are the symptoms that you experience when youare exposed to the EMF?’ Typical EHS sufferers willexplicitly describe the object(s) and what symptom(s)occur when they are exposed to that object. Among theEHS respondents in Study 2, only 5 (5.7%) out of the 88respondents did not openly describe the type ofelectrical objects they were sensitive to and thesymptoms that they experienced when exposed to thoseobjects.

Another important issue to consider when devel-oping an EHS screening tool is that the symptomscannot be explained by a pre-existing condition. Basedon the EHS responses in Study 2, 33 (37.5%) werecurrently suffering from a chronic illness. Of these, 8(9.1%) individuals had moderate symptoms and 25(28.4%) had severe symptoms.

We propose that the following EHS ScreeningTool be used to identify individuals who are EHS: (1) atotal symptom score greater than or equal to 26, (2) theindividual explicitly attributes his or her symptoms toexposure to EMF-producing object(s), and (3) currentsymptoms cannot be explained by a pre-existingchronic illness. Using these criteria, 38 (43.2%) EHSindividuals in Study 2 would fit the profile of someonewho is sensitive to EMFs.

It is important to note that almost 40% of ouroriginal EHS sample also reported suffering from a

EHSQuestionnaire 149

chronic illness and this is the primary reason why lessthan half of the original sample would be classified asfitting the profile of someone who is EHS using theabove proposed EHS Screening Tool.

Estimates of the prevalence of EHS have varieddramatically in the media from a few percent up to 30%[Bergqvist and Vogel, 1997]. Population surveysutilizing one question to identify EHS individuals havereported an incidence rate of 1.5% in Sweden [Hillertet al., 2002] and 3.0% in California, USA [Levalloiset al., 2002].Using ourEHSScreeningTool, 145 (4.0%)of our random sample in Study 1 fit the profile ofindividuals who are sensitive to EMFs.

It is important to note that the above EHSScreening Tool is still reliant on the individuals’ self-report of the symptoms they experience and their beliefthat these symptoms are caused by exposure to EMFs.However, until there is reliable evidence that EMFs docause negative health effects and laboratory tests canmeasure these effects, self-report is the only way inwhich EHS individuals can be identified. Previousstudies have classified individuals as being EHS basedon their response to just one question [e.g., Hillert et al.,2002; Levallois et al., 2002]. The main benefit of theproposed EHS Screening Tool is that it not only takesinto account the individual’s belief as to the cause oftheir symptoms but also includes the degree ofsymptom severity. These criteria therefore provide amore stringent and accurate measure of identifying anEHS individual. Although these criteria are not able todetermine actual sensitivity to EMF, they serve as agood indicator of the subjective severity of symptomsexperienced by EHS individuals when exposed toEMFs.

Importantly, these criteria can be used as a reliabletool in bioelectromagnetic research to identify thoseindividuals that fit the profile of EHS. By using the EHSScreening Tool researchers can pre-select the mostsensitive individuals in terms of their response to EMFexposure to participate in double-blind studies measur-ing possible health effects from EMF exposure.Researchers can also use the eight subscales identifiedin Study 1 to investigate what affect EMF exposure hason different symptom groups. Leitgeb and Schrottner[2003] have demonstrated that there are large individualdifferences in the perception threshold of electric 50 Hzcurrents with women being more electrosensible thanmen. Experimenters could examine if there is arelationship between the intensity of the EMF stim-ulation and perceived severity of symptoms by usingthis questionnaire measure. The multifaceted symptomindices may also be useful in assessing variations insymptoms in response to different therapeutic inter-ventions such as cognitive behavioral therapy.

In conclusion, individuals with EHS experience awide range of non-specific health symptoms that occurnaturally in the general population. When comparedwith the general public, EHS sufferers reported agreater severity of symptoms, poorer levels of generalhealth and well being, and attributed the cause of theirsymptoms to exposure to objects that emit EMFs. Ahigher percentage of respondents with a chronic illnesswere found in the EHS group. In addition, a largerproportion of EHS respondents indicated that theyhad at one time experienced a severe electric shock.Through exploratory factor analysis we have been ableto group these symptoms into eight key subscales anddeveloped a valid and reliable screening tool that can beused to identify individuals who are sensitive to EMFs.The EHS Screening Tool includes a symptom scaleproviding an index for both the type and intensity ofsymptoms commonly reported by EHS individuals.Future development of the EHS Questionnaire mayinvolve the inclusion of information regarding aspectsof illness behavior, coping strategies, and durationand progress of the illness to further refine ourunderstanding of EHS. This tool will be of great valueto researchers in bioelectromagnetics in terms ofimproving the selection and classification of EHSindividuals.

REFERENCES

Angus VC, Entwistle VA, Emslie MJ, Walker KA, Andrew JE.2003. The requirement for prior consent to participate onsurvey response rates: a population-based survey in Gram-pian. BMC Health Serv Res 3:21.

Bergqvist U, Vogel E, editors. 1997. Possible health implications ofsubjective symptoms and electromagnetic fields: A report bya European group of expects for the European commission,DG V. Solna, Sweden: European Commission DG V.National Institute for Working Life.

Flodin U, Seneby A, Tegenfeldt C. 2000. Provocation of electrichypersensitivity under everyday conditions. Scand J WorkEnviron Health 26(2):93–98.

Goldberg D. 1978. Manual of the general health questionnaire.Windsor: NFER Publishing.

Hietanen M, Hamalainen A, Husman T. 2002. Hypersensitivitysymptoms associated with exposure to cellular telephones:No causal link. Bioelectromagnetics 23:264–270.

Hillert L, Kolmodin Hedman B, Soderman E, Arnetz RB. 1999.Hypersensitivity to electricity: Working definition and addi-tional characterization of the syndrome. J Psychos Res47(5):429–438.

Hillert L, Berglind N, Arnetz BB, Bellander T. 2002. Prevalence ofself-reported hypersensitivity to electric or magnetic fields ina population-based questionnaire survey. Scand J WorkEnviron Health 28(1):33–41.

Jacoby K, Jacoby A. 2004. Epilepsy and insurance in the UK: anexplatory survey of the experiences of people with epilepsy.Epilepsy Behav 5:884–893.

150 Eltiti et al.

Newell CE,Rosenfield P,Harris RN. 2004. Reasons for nonresponseon U.S. Navy surveys: a closer look. Mil Psychol 16(supp 4):265–276.

Leitgeb N, Schrottner J. 2003. Electrosensibility and electro-magnetic hypersensitivity. Bioelectromagnetics 24:387–394.

Levallois P. 2002. Hypersensitivity of human subjects to environ-mental electric and magnetic field exposure: A review of theliterature. Environ Health Perspect 110(4):613–618.

Levallois P, Neutra R, Lee G, Hristova L. 2002. Study of self-reported hypersensitivity to electromagnetic fields in Cal-ifornia. Environ Health Perspect 110(4):619–623.

Nunnaly JC. 1978. Psychometric theory, 2nd edition. New York:McGraw-Hill.

Ofcom Sitefinder. [undated]. Available from: http://www.sitefin-der.radio.gov.uk/.

Rubin GJ, Das Munshi J, Wessely S. 2005. Electromagnetichypersensitivity: A systematic review of provocation studies.Psychosom Med 67:224–232.

Stevens J. 1992. Applied multivariate statistics for the socialsciences. Hillsdale, NJ: Lawrence Erlbaum Associates.

Tabachnick BG, Fidell LS. 1996. Using multivariate statistics, 3rdedition. New York: HarperCollins College Publishers.

EHSQuestionnaire 151