occup med (lond) 1998 hocking 357 60

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Occup. Med. Vol. 48, No. 6, pp. 357 -360 , 1998Copyright 1998 Ltppincott Williams & Wilkins for SOMPrinted in Great Britain. All rights reserved0962-7480/98

Preliminary report:Symptoms associated withmobile phone useB . Hocking9 T yrone Street, Cam berwell, Victoria, Australia 3124Mobile phone use is ubiquitous, although the alleged health effects of low level radio-frequen cyradiation (RFR) used in transmission are contentious. Following isolated reports ofheadache-l ike symptoms arising in some users, a survey has been conducted to characterizethe symptoms sometimes associated with mobile phone usage. A notice of interest in caseswas placed in a major medical journal and this was publicized by the media. Respond ents w ereinterviewed by telephone using a structured questionnaire. Forty respondents from diverseoccupations described unpleasant sensations such as a burning feeling or a dull ache mainlyoccurring in the tempora l, occipital or auricular areas. The symptom s often began minutes afterbeginning a call, but could come on later during the day. The symptoms usually ceased withinan hour after the call, but could last unti l evening. Symptoms did not occur when using anordinary handset, and were different from ordinary headaches. There were several reportssuggestive of intra-cranial effects. Three respo nden ts reported local symptom s associated withwearing their mobile phone on their belts. There was one cluster of cases in a workplace.Seventy-f ive per cent of cases were associated with digital mobile phones. Most of therespondents obtained rel ief by altering their patterns of telephone usage or type of phone.Cranial and other diverse symp toms may arise associated w ith mobile phone us age. Physiciansand users al ike should b e alert to this. Further wo rk is needed to determ ine the range of effects,their mechanism and the possible implications for safety l imits of RFR.Key words: Mobile phones; radiofrequency radiation; symptoms.Occup. Med. Vol. 48, 357-3 60, 1998Received 6 October 1997; accepted in final form 16 February 1998.

I N T R O D U C T I O NMobile phone usage is ubiquitous. In Australia witha population of 18 million peop le there are over 3 millionmobile phones which utilize analogue (830 M Hz FM )or digital (GSM 900 M Hz, 217 Hz pulses) radio-frequency radiation (RFR ). Mobile phones may be usedas hand-held, hands-free fitted into a car, a 'hands-freekit' (consisting of an ear and mouthpiece connected toa transmitter worn on the belt) or a transportable (bag)mobile phone. The RFR emitted from the hand-heldtelephones is low, about 600 mW average for analogueand 2 W peak (125 mW average) for digital phon es.Digital and analogue mobile phones also send brief loca-tion updates, four or more times an hour, tosurrounding mobile phone base stations when not inuse. The International Commission on Non-Ionizing

Correspondence and reprint requests to: Dr B. Hocking, Consultant inOccupational Medicine, 9 Tyrone Street, Camberwell, Victoria, Australia3124.

Radiation Protection has stated that the localized RFRlimit for general public ex posure (2 W/kg) will not beexceeded by handsets with duty cycle weighted powersless than 600 raW for 900 M Hz fields.1 This assumes anantenna to head separation of 1.4 cm (ICNIRP 1995).However, the health effects of low level RFR are a matterof controversy.For some years prior to 1995 I had received reportsfrom users of mobile phones regarding symptoms arisingfrom their use, such as the following:

1. 'It has been noted that by using the mobile phon ein the transmit m ode, the side of the head closestto the phone heats up and at different p eriods oftime persistent migraines appear.'2. 'I have noticed persistent strong headaches fora period of 4 days; worsening after using themobile phone for extended periods of time(approx. 10-15 minutes, 4-5 times a day).These headaches have been occurring on theleft side of my head, adjacent to phone andaerial.'

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3. 'I've also noticed migraines to the side of thehead which sort of goes away on the weekend,when we don't use the mobile phone. But itpersists during the weeks since we had thephones.'Subsequently a survey was undertaken to help better

characterize the nature of the symptoms as an aid tofurther research. This preliminary report complementsother (laboratory and epidemiological) studies currentlyin progress in the UK, Sweden and Finland.

METHODSRespondents were recruited by a notice in a medicaljournal in 1996 which led to some media publicity. Re-spondents contacted the writer and were subsequentlyinterviewed at length by telephone. The interview wasconducted using a questionnaire developed for this pur-pose with the international collaborators in the UK andSweden. The questionnaire had three main parts: the firstelicited information about general health and headachehistory; the second obtained details of symptoms asso-ciated widi mobile phone usage; and the third part ob-tained information about the types of telephones used.Data were then coded and analyzed.

RESULTSThere were 50 initial respondents of whom 40 (80%)were subsequently contacted for interview. Reasons fornon-response included being overseas, non-response tocalls and not wishing to participate.Seventy-five per cent of respondents were male; themajority were aged between 30 and 49; and they livedin Queensland, New South Wales, Victoria, SouthAustralia and Western Australia. Their occupations werediverse and included computer-related workers (six),managers (three), housewives (three), photographers(two), farmer, mec hanic, pilot, solicitor, etc. Two workedfor telephone companies.Nearly all respondents described their health asgood. Five had histories of headaches, and five had atsome time suffered a migraine. Thirteen had allergies(penicillin, milk, etc.), but none reported they hadelectro-sensitivity or multiple chemical sensitivity.Twenty-nine (75%) had fillings in their molar teeth.Three had a serious illness (cancer, heart disease,hypothyroidism) which was under control.The symptoms arising from the mobile phone mainlyaffected the head and, for a few, the waist (see Table 1).The most common site (17) was the 'temple' area; ninefelt symptoms in the ear and nine on the occipital area.The pain radiated in a few to the jaw, neck, shoulders orarm. For 10 the symptom s were described as a dull pain;an unpleasant warmth or heating by 11 and various otherpainful sensations such as ache, throb , sharp and pressureby others. On a pain scale of 1-5, (1 = least, 5 = most), 18rated the pain as 2, and 11 rated it as a 3. All coulddistinguish the sensations from ordinary headache.

Table 1 . Symptoms reported by 40 mobile phone usersSymptom Number (%)

(88)179911101423121916

111523

(48)(26)(26)(31)(29)(40)

(65)(35)

(54)(46)

(31)(43)(5)(7)

Cranial symptoms 35Site on head

TempleEarOcciputType of painHeat /warmthDull painOther

Onset


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B. Hocking: Preliminary report: Symptom s associated with mobile phone use 359

Three respondents associated symptoms about theirlumb ar area to wearing a mobile phone on their belt. Onereported pain in the area at night time and another felta cold area the size of a saucer. The location of symptomswas dependent on the side the mobile phone was carriedand moved sides with the phone. A third person had aninjury to the right flank many years ago; wearing themobile phone caused similar pains in the previously in-jured muscles.

Three staff from one organization reported symptoms.About 30 mobile phones had been issued and sub-sequently staff informally learnt that others had symp-toms. The episode was notified to the state Workcover(compensation) authority.Two respondents had unusual symptoms. One de-veloped a warm feeling and then a blistering loss of skinon the contralateral cheek after a prolonged call; the otherreported headaches when clients in her office used theirmobile phone.Nineteen respondents had a mobile phone fitted totheir car; 14 had an external aerial and did not get head-aches when it was used.The makes of mobile phones were those of majorcompanies. Twenty-eight respondents associated symp-toms with digital (GSM) phones and 10 with analogue.Of the former, 13 said they had tried an analogue withoutsymptoms developing, and two of the latter group had nosymptoms with digital phones. Twenty-two said theyused the mobile phone more than five times a day.Thirty-fou r had changed their use of the mobile phone asa result of the symptoms, often using it as a pagerand some had switched to 'hands-free kits', which had

relieved their symptoms.DISCUSSIONThis paper is intended to characterize the syndrome ofsymptoms associated with mobile phone usage and is, toour knowledge, the first of its kind to be published. Thesymptoms are felt in the temporal, auricular, or occipitalareas and are often described as a dull or burning pain.The unpleasant sensations may begin within minutes ofbeginning a call or come on with usage during the day.The symptoms may cease within the hour after a call orlast till bedtime . Some cases have symp toms suggestive ofintra-cranial effects on vision, inner ear and cognitivefunction. Symptoms do not occur with ordinary handsetusage. Symptoms may occur around the waist when themobile phon e is worn on the belt.All respon dents were interviewed for 15-30 min byBH. This permitted thorough exploration of symptomsand perhaps gathered data that could have been missedby a mail-out questionnaire or interviews by non-medicalpersonnel.It is recognized that there may be self-selection biaswith regard to the respondents. However the veracity oftheir symptoms is suggested by their similarity to theoriginal unsolicited reports (reports 1-3); the recognitionby respondents of symptoms before publicity began(1996 ); the basically favourable attitude of respondents to

mobile phones; the occurrence of symptoms in anatom-ical sites not imm ediately close to the antenn a; the occu r-rence of reports Australia-wide; and the fact thatthree-quarters of respondents had spontaneously takensensible steps to lessen symptoms by altering telephoneusage argues against neurotic behaviour. Also, the occur-rence of 'headaches' was noted in the laboratory settingwith similar exposures 30 years ago. Frey 2 has describedhow in the course of an experiment he and his volunteersdeveloped headaches during exposure to the side of thehead from 1.3 GH z radar-pulsed RFR at 400 |iW/cm 2averaged power. (The estimated energy from a mobilephone is similar). Reports of cranial symptoms are nowbeing reported from Sweden, the UK, the USA andNew Zealand.3

The cranial symptoms differ from headaches such asmigraine or cluster or tension headaches or temporo-mandibular joint dysfunction, by their site or time ofonset or duration.4 Cervical neuralgia from 'cradling' themobile phone in the neck is an unlikely explanation be-cause several had used analogue telephones withoutsymptoms and then on changing to a digital phone de-veloped symptoms; it is unlikely their method of holdingthe mobile phone suddenly changed. The absence of skinrashes and relevant history is not consistent with electricalhypersensitivity.The mechanism of the effect may be speculated. Thefact that none of the responden ts suffered symp tomswhen using an ordinary hand-set argues against a posi-tional effect and also against a call-content related psy-chological reaction. The onset of symptoms withinminutes in many respondents suggests a neural mecha-nism, although a vascular component could be involved.Th e sym ptoms in the flank of the person with a previousinjury suggests stimulation of neuromas in damagednerves by the location pulses.The innervation of the scalp and ear is complex. Thesuperior anterior pa rt of the ear is supplied by the superfi-cial temporal branch of the maxillary division of thetrigeminal nerve. This also innervates the 'temple'. Muchof the pinna and the occipital area of the scalp is innerv-ated by the greater auricular nerve from C2 and 3. Theexternal ear and meatus is also supplied by the glosso-pharyngeal and vagus nerves. These various nerves couldprovide the basis of nociception or referred pain such asto the arm.Mobile phones can warm adjacent tissue due to theirbattery and circuits, as well as emit RFR. The respon-dents did not relate symptoms to the cheek which isdirectly heated and highly vascular. Justesen et al. hasnoted that RFR (2.4 GHz) can warm tissue and causea prolonged sensation after the stimulus has ceased, how -ever this requires an energy of at least 27 mW /cm2 whichis much greater than that from mobile phon es.5'6Chou and Guy found that strong pulsed or continuouswave 2.45 GH z radiation was not able to elicit actionpotentials in isolated frog nerves.7 Pakhomov found nervevelocities did not change but potential amplitudes de-creased using 915 MH z pulsed waves.8 Seaman andWachtel ob served increased firing rates of /Ip/asia-gangliaexposed to 1.5 and 2.5 GHz continuous wave radiation


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360 Occup. Med. Vol. 4 8 , 1998

which further increased when pulsed.9 Bolashakov andAleksew found 900 MH z pulsed (bu t not CW ) increasedbursts of firing of Lymnea neurons.10 Thus, low levelRFR at relevant frequencies has not been found to initiatean action potential but can affect nerve firing rates. Thiscould cause dysaesthesia. Th e A delta fibres of nerves areresponsible for pain and warmth feelings and requirespecial neurophysiological techniques to evaluate them.They are particularly sensitive to 250 Hz currents; 11 pul-sed mobile phones operate at 217 Hz. T he nerves on theface are more sensitive to stimulation than those on thearms and legs and there is a wide variation in sensitivitybetween sub jects.'' Subthreshold stimulation and adapta-tion could account for variations in onset and remissionof cranial symptoms in different respondents. A com-bined effect on nerves of RFR and heating may beconsidered.

It is feasible that a vascular component could contri-bute to the symptoms. An effect on blood vessels couldcontribute to pain12 or to migraine or other intra-cranialsymptoms.13 Salford14 has evidence of an effect on theblood-brain barrier from low-level exposures in mice,and French has preliminary evidence of an effect by830 M Hz RFR on endothelial cell cultures (personalcommunication).La i et al.15 have found that rats exposed to low levels ofRFR have impairment of learning and an associatedchange in acetylcholine receptor levels. This may be rel-evant to some of the apparently cognitive symptoms.Reports of EEG changes after mobile phone use havebeen inconsistent. Stimulation of the semi-circular canalscould contribute to otological symptoms, although click-sounds as described by Frey in radar workers were notreported.16 The above mechanisms are not mutuallyexclusive.

The energy from a mobile phone incident on the facehas been measured by Bolzano et al. in studies on humanmodels.17 The energy is mainly deposited in the cheekanterior to the ear with lesser levels elsewhere. Th e levelsin the cheek are approximately 1 W/Kgm, which isaround half of the present safety levels as set out byICNIRP.1This survey does not attempt to assess the prevalenceof symptoms. However, the occurrence of a cluster ofcases in one workplace in this survey (and an unreportedone similarly involving some four staff out of about 30)suggests a low level prevalence of susceptibility.This survey has begun to characterize the mainfeatures of the cranial and other symptoms sometimesassociated with mobile phone use as a basis for epi-demiological or laboratory studies. Epidemiological stu d-ies require definition of a case and this paper is intendedto help to characterize the symptoms which then consti-tute a case; the possibility of diverse intra-cranial effects

should be sought in any further surveys. Laboratorystudies should include double blind testing of patientsto confirm if RFR is causative of their symptoms. It isdesirable that users and the m edical profession alike rec-ognize that mobile phones appear to cause a variety ofsymptoms in some individuals. In addition, the apparentoccurrence of symptoms at levels below the allowablelimits raises questions about the current safety levelsof RFR.

REFERENCES1. ICNIRP. Health issues related to the use of hand-held radio tele-phones and base transmitters. Health Physics 1996; 70: 587 -590.2. Frey A. Headaches from cellular phones: are they real and what arethe implications? Environ Health Perspect 1998; 106: 101-103.3. European Commission Expert Group. Possible Health EffectsRelated to the use ofMobile Phones. Didcot, UK: European Commis-sion Expert Group, UK National Radiation Protection Board,

1996: 65 .4. Martin J. Headache. In: Wilson J, et al., eds. Harrisons Principles ofInternal Medicine, 12th Edition. New York, NY (USA): McGraw-Hill, 1991.5. Justesen D , Adair E, Stevens J, et al. A com parative study of humansensory thresholds. Bioelectromagnetics 1982; 3: 117 -125.6. Adair E. Thermoregulation in the presence of microwave fields. In:Polk C, Postow, eds. Handbook of Biological Effects of Electro-magnetic Fields. Boca Raton, FL (USA): CRC Press, 1996.7. Chou CK, Guy A. Effects of electromagnetic fields on isolatednerve and muscle preparations. IEEE Trans Microwave Theory Tech1978; 141: 26 .8. Packhomov A, Dubovick B, Kilupayer V, et al. Search for micro-wave-sensitive structures and functions in the nervous system.Fourteenth Annual IEEE/EMBS, Paris, 1992: 297.

9. Seaman R, Wachtel H. Slow and rapid responses to CW and pulsedmicrowave radiation by individual Aplysia pacemakers. J Micro-wave Power 1978; 13: 77-85.10. Bolshakov M, Alekseer S. Bursting responses of Lymnea neurons tomicrowave radiation. Bioelectromagnetics 1992; 123: 119-126 .11. Katims J,Noviasky E, R endell M , et al. Constant current sine wavetranscutaneous nerve stimulation for the evaluation of peripheralneuropathy. Arch Phys Med Rehabil 1987; 68: 210-213 .12. Burnstock G. A unifying purinergic hypothesis for the initiation ofpain. Lancet 196; 347: 1604-1605 .13. Lance J.Migraine: then and now [Editorial]. MedJAust 1996; 164:519-520.14. Salford L, B run A, Eberhard t, et al. Electromagnetic field-induced permeability of the blood-brain barrier shown by imm uno-histochemical methods. In: Ramel C, Norden B, eds. InteractionMechanism s of Low-Leve l Electromagnetic Fields in Living Systems.Oxford, UK: Oxford Science Publications, 1992: 251.15. Lai H, Carino M, Horita A, Guy A. Opiod receptor subtypes that mediate a microwave-induced decrease in central cholinergicactivity in the rat. Bioelectromagnetics 1992; 13: 237-246.16. Frey A. Human auditory system response to modulated electro-magnetic energy. Applied Physiol 1962; 17: 689-692.17. Balzano Q, Garay O, Manning T. Electromagnetic energy expo-sure of simulated users of portable cellular telephones. IEEE TransVehic Tech 1995; 44: 390-403.


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