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Page 1: Health risks from the use of mobile phones - NTUAusers.ntua.gr/mmakro/healthrisk-mobile.pdf · Health risks from the use of mobile phones Michael H. Repacholi * Occupational and En6ironmental

Toxicology Letters 120 (2001) 323–331

Health risks from the use of mobile phones

Michael H. Repacholi *Occupational and En6ironmental Health, World Health Organization, 1211 Gene6a 27, Switzerland

Abstract

Widespread concerns have been raised about the possibility that exposure to the radiofrequency (RF) fields frommobile telephones or their base stations could affect people’s health. Such has been the rapid growth of mobiletelecommunications that there will be about one billion mobile phone users before 2005. Already there are moremobile than fixed-line users. Developing countries are establishing mobile telecommunications rather than the moreexpensive fixed-line systems. Thus, if there is any impact on health from mobile telephones, it will affect everyone inthe world. The World Health Organization (WHO) established the International EMF Project in 1996 to evaluate thescience, recommend research to fill any gaps in knowledge and to conduct formal health risk assessments of RFexposure once recommended research had been completed. In addition, the UK government established anindependent expert group to review all the issues concerning health effects of mobile telephones and siting of basestations. Cancer has been suggested as an outcome of exposure to mobile telephones by some scientific reports. Thispaper reviews the status of the science and WHO’s programme to address the key issues. In addition, the mainconclusions and recommendations of the UK expert group will be summarised. © 2001 Elsevier Science Ireland Ltd.All rights reserved.

Keywords: Mobile phones; Health effects; Radiofrequency fields; Cancer

www.elsevier.com/locate/toxlet

1. Introduction

Concern continues about exposure to radiofre-quency (RF) fields from sources used for mobiletelecommunications, radars, radio and televisionbroadcast, medical and industrial applications.Much of this concern arises because new tech-nologies are introduced without provision of pub-lic information about their nature or discussion ofthe debate within the scientific community aboutpossible health consequences. In the meantime,

mobile phone use has increased dramatically withfalling costs. Industry sources suggest that therewill be over one billion users worldwide by 2005,far exceeding telephone use via fixed-lines.

Of particular concern to the World Health Or-ganization (WHO) is the fact that, if any adversehealth effect is established from mobile phone use,it will be a global concern because developingcountries are establishing this technology in pref-erence to the more-expensive fixed line systems.Thus, even a small impact on health could have amajor public health consequence.

The output power from the antennas of digitalmobile telephones is much lower than the earlier

* Tel.: +41-22-7913427; fax: +41-22-7914123.E-mail address: [email protected] (M.H. Repacholi).

0378-4274/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved.

PII: S 0378 -4274 (01 )00285 -5

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M.H. Repacholi / Toxicology Letters 120 (2001) 323–331324

technology analogue models. However, RF emis-sions from the base stations that communicatebetween the mobile phones and the networks areorders of magnitude smaller than from handsets.Yet the key concern of the public has been theapparently ad hoc erection of base stations intheir living environment without adequate consul-tation. To compound the problem, the media seeselectromagnetic fields (EMF) as a newsworthyissue so that newly published scientific research issensationally reported without qualification fromthe results of previous studies.

To address these concerns, WHO establishedthe International EMF Project in 1996 and iscollaborating with eight international organiza-tions, seven WHO collaborating institutions andover 45 national authorities. The InternationalEMF Project, in collaboration with the Interna-tional Commission on Non-Ionizing RadiationProtection (ICNIRP), has completed initial inter-national scientific reviews of possible health ef-fects of exposure to EMF. These reviews provideinterim conclusions on health hazards from expo-sure to EMF and gaps in knowledge requiringfurther research before better health risk assess-ments could be made by WHO. Results of the RFreview covering the frequency range 10 MHz to300 GHz have been published (Repacholi, 1998).An updated review was completed in late 1999and the results will be published in early 2001.

Sufficient concern was voiced in the UK thatthe Minister for Public Health established an In-dependent Expert Group on Mobile Phones(IEGMP) ‘To consider present concerns about thepossible health effects from the use of mobilephones, base stations and transmitters, to conducta rigorous assessment of existing research and togive advice based on the present state of knowl-edge. To make recommendations on further workthat should be carried out to improve the basisfor sound advice.’ This group has now publishedits report (IEGMP, 2000) and the results areavailable on its web site: http://www.iegmp.org.uk.

This paper summarises the results of the WHOand IEGMP reviews with respect to health conse-quences from mobile phone use, research neededto evaluate properly possible health effects re-

quired to make better health risk assessments, andwhat WHO will be doing to resolve this issue.Finally, a summary of WHO recommendations isgiven on what can be done while research iscompleted and evaluated.

2. WHO requirements for evaluating health risks

Unfortunately, there have been many publishedRF studies that have either been of insufficientquality to contribute to health risk assessments, orthey have been unconfirmed but raise potentiallyserious health questions and so need confirma-tion. To address the former, WHO has publishedits requirements for quality research, what re-search is still needed to assess health risks andhow health risks are evaluated. These are sum-marised in the following.

2.1. Quality research

For new studies to be useful to future healthrisk assessments, the research must be of highscientific quality with clearly-defined hypotheses,estimates should be given of the ability of thestudy to detect small effects, and protocols thatare consistent with good scientific practice shouldbe used. Quality assurance procedures should beincluded in the protocol and monitored during thestudy.

2.2. Biological effects and health hazards

The WHO constitution defines health as a stateof complete physical, mental and social well be-ing, and not merely the absence of disease orinfirmity. This definition includes an importantsubjective component that must be taken intoaccount in health risk assessments. Within theInternational EMF Project, a working definitionof health hazard has been developed: A healthhazard is a biological effect outside the normalrange of physiological compensation that is detri-mental to health or well being. In this definition,a biological effect is a physiological response toexposure. For the biological effect to lead to someadverse health consequence, it should be outside

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M.H. Repacholi / Toxicology Letters 120 (2001) 323–331 325

the normal range of compensation, in order toplace it beyond normal variation in bodyresponses.

2.3. Determining research needs

Criteria used to evaluate health risks by theInternational EMF Project were adapted fromthose used by WHO’s International Agency forResearch on Cancer (IARC) (Repacholi andCardis, 1997). Thus, to determine research re-quirements, it was first necessary to assess whatthe composition of a database of research resultsshould include for IARC and WHO to assesshealth risks comprehensively. Research needswere also identified when published evidence for ahealth risk was judged suggestive, but insufficientto meet the criteria for assessing health risk. Re-search needs were also established on the basis ofunconfirmed effects having implications forhealth, and replication of key studies to confirmeffects. Thus, the overall goal is to promote stud-ies that demonstrate a reproducible effect of EMFexposure that has the likelihood to occur in hu-mans and has a potential health consequence.

While in vitro studies can provide importantinsights into fundamental mechanisms for biologi-cal effects from exposure to low-level EMF, invivo studies, whether on animals or human be-ings, provide more convincing evidence of adversehealth consequences. Epidemiological studiesprovide the most direct information on risks ofadverse effects in human beings. However, thesestudies have limitations, especially when low rela-tive risks are found. Epidemiological studies areimportant for monitoring public health impact ofexposure, particularly from new technologies.

Priority should be given to studies designed toinvestigate health hazards of:� concern to the general public;� potential public health importance (based on

the size of the populations potentially exposed,the extent of their exposure, and the serious-ness of the hypothesised adverse effect);

� scientific importance (e.g. testing the relevanceof effects observed or mechanisms postulatedon the basis of in vitro or in vivo results).

3. Mechanisms of interaction

RF fields induce torques on molecules that canresult in displacement of ions from unperturbedpositions, vibrations in bound charges (both elec-trons and ions), and rotation and reorientation ofdipolar molecules such as water. These mecha-nisms, which can be described by classical electro-dynamic theory, are not capable of producingobservable effects from exposure to low-level RFfields, because they are overwhelmed byrandom thermal agitation. Moreover, the re-sponse time of the system must be fast enough toallow it to act within the time period of theinteraction. Both considerations imply thatthere should be a threshold (below which noobservable response occurs) and a cut-off fre-quency (above which no response is observed).These thresholds would be expected to be presenteven in more refined models if they correctly takeinto account thermal noise and the kinetics of thesystem.

Exposure to EMF at frequencies aboveabout 100 kHz can lead to significant ab-sorption of energy and temperature increases. Ingeneral, exposure to uniform (plane-wave) EMFresults in a highly non-uniform deposition anddistribution of energy within the body, whichmust be assessed by dosimetric measurementand calculation. For absorption of energy by thehuman body, EMF can be divided into fourranges:� about 100 kHz to less than about 20 MHz,

where absorption in the trunk decreases rapidlywith decreasing frequency, and significant ab-sorption may occur in the neck and legs;

� from about 20 MHz to 300 MHz, atwhich relatively high absorption can occur inthe whole body, and to even higher values ifpartial body (e.g. head) resonances are consid-ered;

� from about 300 MHz to several GHz, at whichsignificant local, non-uniform absorptionoccurs;

� above about 10 GHz, at which energy absorp-tion occurs primarily at the body surface.In tissue, the specific absorption rate (SAR) of

RF energy absorbed per unit mass is proportional

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to the square of the internal electric field strength.The average SAR and SAR distribution can becomputed or estimated from laboratory measure-ments. Values of SAR depend on the followingfactors.� The incident field parameters, i.e. the fre-

quency, intensity, polarization, and source–ob-ject configuration (near field or far field).

� The characteristics of the exposed body, i.e. itssize, internal and external geometry, and thedielectric properties of the various tissues.

� Reflection, absorption and scattering effects as-sociated with the ground or other objects in thefield near the exposed body.When the long axis of the human body is

parallel to the electric field vector, and underplane-wave exposure conditions (i.e. far-field ex-posure), whole-body SAR reaches maximal val-ues. The amount of energy absorbed depends on anumber of factors, including the size of the ex-posed body. ‘Standard Reference Man’, if notgrounded, has a resonant absorption frequencyclose to 70 MHz. For taller individuals the reso-nant absorption frequency is somewhat lower,and for shorter adults, children, babies, andseated individuals it may exceed 100 MHz. Thevalues of electric field exposure limits are basedon the frequency dependence of human absorp-tion. In grounded individuals, resonant frequen-cies are lower by a factor of about 2 (ICNIRP,1998).

This description of RF absorption applies towhole-body exposure from distant sources such asbase stations. However, mobile phone antennasgive localised RF exposures predominantly to thehead. Thus, it is necessary to determine the localSAR and its distribution in the head toproperly evaluate health consequences. Calcula-tion of the maximum temperature rise in the headfrom RF exposure during mobile telephone usesuggests that increases of no more than about0.1°C would be expected (Van Leeuwen et al.,1999). Thus if there are health effects from low-level RF exposure, they are unlikely to be due toany temperature increase. So-called non-thermalmechanisms of RF action in tissues have beenproposed, but none have received experimentalsupport.

4. Biological effects of exposure to RF fields

The following summarises the results and con-clusions of the WHO (Repacholi, 1998) andIEGMP (2000) reviews, as well as more recentresults, with emphasis on the possibility that RFexposure could result in cancer.

There is little information about possible healtheffects from localised RF exposures or about theeffects of different pulsing regimens that RF fieldsare used in mobile telecommunications; this iswhere there are gaps in knowledge. A summary ofthe results of studies investigating effects of RFexposure on living systems is given in thefollowing.

4.1. In 6itro studies

Reports from in vitro research indicate thatlow-level RF fields may alter membrane structuraland functional properties that trigger cellular re-sponses. It has been hypothesised that the cellmembrane may be susceptible to low-level RFfields, especially when these fields are amplitudemodulated at low frequencies. At high frequen-cies, however, low-level RF fields do not induceappreciable membrane potentials. They can pene-trate the cell membrane and possibly influencecytoplasmic structure and function. These RFfield-induced alterations, if they occur, could beanticipated to cause a wide variety of physiologi-cal changes in living cells that are only poorlyunderstood at the present time (Repacholi, 1998).

A lack of effects of RF exposure on mutationfrequency has been reported in a number of testsamples including yeast and mouse lymphoidcells. No effect of RF-field exposure on chromo-some aberration frequency in human cells hasbeen confirmed (IEGMP, 2000).

4.2. In 6i6o studies

In contrast to the evidence already given, sev-eral studies indicate that RF fields may affectDNA directly. These papers (Lai and Singh, 1995,1996) report quantitative data subject to sourcesof inter-trial variation and experimental errorsuch as incomplete DNA digestion or unusually

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M.H. Repacholi / Toxicology Letters 120 (2001) 323–331 327

high levels of background DNA fragmentation(IEGMP, 2000). These experiments have not beenreplicated (Malayapa et al., 1997a,b, 1998). Fur-thermore, most well conducted investigations re-port a lack of clastogenic effect in the somatic orgerm cells of exposed animals (ICNIRP, 1998).Other investigations that require further attentionrelate to possible synergistic action of RF expo-sures with chemical or physical mutagens orcarcinogens.

Most cancer studies of animals have soughtevidence of changes in spontaneous or naturalcancer rates, enhancement by known carcinogens,or alterations in growth of implanted tumours(IEGMP, 2000). However, they have providedonly equivocal evidence for changes in tumourincidence. Chronic RF field exposure of mice at2–8 W/kg resulted in an SAR-dependent increasein the progression or development of spontaneousmammary or chemically induced skin tumours. Ina further study, exposure at 4–5 W/kg, followedby application of a sub-carcinogenic dose of achemical carcinogen to the skin, a procedure re-peated daily, eventually resulted in a threefoldincrease in skin tumours (Szmigielski et al., 1982,1988; Szudzinski et al., 1982). However, at thesehigh exposures, temperature-mediated effects can-not be excluded.

Studies in which cancer cells were injected intoanimals have reported a lack of effect from expo-sure to continuous wave (CW) and pulsed RFfields on tumour progression. Progression ofmelanoma in mice was unaffected by daily expo-sure to pulsed or CW RF fields following subcuta-neous implantation, and progression of braintumours in rats was not affected by CW or pulsedRF fields following the injection of tumour cellsinto the brain.

Moderately lymphoma-prone Em-Pim1 onco-gene-transgenic mice were exposed or sham-ex-posed to radiofrequency fields for 1 h/day for upto 18 months using pulse modulations similar tothat used for digital mobile telephones. Exposurewas associated with a statistically significant 2.4-fold increase in the risk of developing lymphoma(Repacholi et al., 1997). This long-term studyneeds replication and extension to other exposurelevels and animal models before it can be used for

health-risk assessments. Further research is alsoneeded to determine the significance of effects inthis transgenic model for human health risk.

In their review of cancer studies, the IEGMP(2000) concluded that: some individual experi-mental studies have suggested that RF radiationcan initiate tumour formation, enhance the effectsof known carcinogens or promote the growth oftransplanted tumours. However, in some of these,the intensity was high enough to produce thermaleffects. The balance of evidence, from both invitro and in vivo experiments, indicates that nei-ther acute nor chronic exposure to RF fieldsincreases mutation or chromosomal aberrationfrequencies when temperatures are maintainedwithin physiological limits (UNEP/WHO/IRPA,1993). This suggests that RF exposure is unlikelyto act as a tumour initiator. Furthermore, a vari-ety of cancer studies using animals have soughtevidence of an effect of RF exposure on sponta-neous or natural cancer rates, the enhancement ofthe effects of known carcinogens or effects on thegrowth of implanted tumours. However, theyhave provided equivocal evidence for an effect ontumour incidence (ICNIRP, 1998; Moulder et al.,1999; Repacholi, 1998; Royal Society of Canada,1999).

5. Behaviour

Early signs of neurotoxicity are often be-havioural rather than anatomical (Salzinger,1994). The behaviour of animals can be a verysensitive indicator of adverse health consequencesand can be used to investigate the biological basisof memory, and studies with non-human primatescan serve as a model of human cognitive func-tions. Early studies were conducted using whole-body exposure to high RF levels or low averagelevels using high peak-power pulses. These studiesproduced behavioural changes that were consid-ered to have potential health consequences at thelowest RF exposures and form the basis for inter-national guidelines limiting human exposure toRF.

Effects on behaviour have been obtained atexposure levels well above guideline limits, but

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some studies have reported effects on behaviourat levels below these limits. Also, few relevantexperiments have used low-level fields with char-acteristics similar to those used in telecommunica-tions systems (UNEP/WHO/IRPA, 1993;Repacholi, 1998; Royal Society of Canada, 1999).Replication and confirmation studies are neededto provide further information on these effects.

In the most recent review of behavioural effects(IEGMP, 2000), this committee concluded that:‘‘Increases in core temperature of 1°C or morecertainly lead to changes in the performance ofwell-learned tasks and other simple behaviours.However, there is no consistent experimental evi-dence that exposure to low level RF fields affectslearning and memory in animals. The studies ofLai and co-workers challenge these conclusionsand suggest that spatial learning can be disturbedat average SARs below 1 W/kg. However thepeak-pulse energy was much higher than thatassociated with mobile phones, the effects re-ported were statistically weak and they have notbeen reproduced by Sienkiewicz et al. (2000) using900 MHz fields. D’Andrea (1999) has speculatedthat some cognitive tasks may show particularsensitivity to RF exposure, and effects on thesebehaviours may occur at SARs below those re-quired to disrupt simple, well-learned tasks.’’

6. Pulsed radiation studies

Exposure to very intense pulsed RF fields sup-presses the startle response and evokes bodymovements in conscious mice (ICNIRP, 1998).The mechanism for these effects is not well estab-lished, and is clearly associated with heating athigher absorbed energies.

People having normal hearing perceive pulse-modulated RF fields with carrier frequencies be-tween about 200 MHz and 6.5 GHz; the so-calledmicrowave hearing effect (Chou et al., 1985). Thesound has been variously described as a buzzing,clicking, hissing or popping sound, depending onmodulation characteristics. Prolonged or repeatedexposure may be stressful.

The retina, iris and corneal endothelium of theprimate eye were reported to be susceptible to

low-level RF fields, particularly when pulsed. Var-ious degenerative changes in light sensitive cells inthe retina were reported at specific energies perpulse (10 ms pulses at 100 p.p.s.), as low as 2.6mJ/kg after the application of a drug used inglaucoma treatment. However, these results couldnot be replicated for CW fields. Further replica-tion studies are needed.

7. Epidemiological and human volunteer studies

7.1. Cancer

By far the greatest public concern has been thatexposure to low-level RF fields may cause cancer.Of the epidemiological studies addressing possiblelinks between RF exposure and excess risk ofcancer, some positive findings were reported forleukaemia and brain tumours. Overall, the resultsare inconclusive and do not support the hypothe-sis that exposure to RF fields causes or influencescancer.

Review groups evaluating possible links be-tween RF exposure and excess risk of cancer haveconcluded that there is no consistent evidence of acarcinogenic hazard. In some studies, there aresignificant difficulties in assessing disease inci-dence with respect to RF exposure and with po-tential confounding factors such as extremely lowfrequency and chemical exposure. Overall, theepidemiological studies suffer from inadequate as-sessment of exposure and confounding, and poormethodology. Further studies are underway toevaluate potential carcinogenic effects of chronicexposure to low-level RF fields and more areneeded.

From their review of epidemiological studiesrelated to cancer outcomes, IEGMP (2000) con-cluded: the epidemiological evidence currentlyavailable does not suggest that RF exposurecauses cancer. This conclusion is compatible withthe balance of biological evidence, which suggeststhat RF fields below guidelines do not causemutation, or initiate or promote tumour forma-tion. However, mobile phones have not been inuse for long enough to allow comprehensive epi-demiological assessment of their impact on health,

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and we cannot, at this stage, exclude the possibil-ity of some association between mobile phonetechnology and cancer. In view of widespreadconcern about this issue, continued research isessential.

7.2. Other health outcomes

Other health outcomes investigated followingRF exposure include headaches, general malaise,short-term memory loss, nausea, changes in elec-troencephalography and other central nervoussystem functions, and sleep disturbances. Therehave been anecdotal reports from several coun-tries of subjective disorders such as headachesassociated with the use of mobile telephones.Whether exposure to RF fields at very low-levelscan cause such subjective effects has not beensubstantiated from current evidence, but furtherresearch is indicated (Repacholi, 1998).

Individuals have claimed to be hypersensitiveto EMF. The most common symptoms areheadaches, insomnia, tingling and rashes of theskin, difficulty in concentrating and dizziness.Given the limited evidence and widespread con-cerns that the presented effects have provoked,more research is needed to determine whetherthese health effects can be substantiated. Currentevidence suggests that these symptoms are psy-chosomatic and unrelated to EMF exposure(Bergqvist and Vogel, 1997; COST 244bis, 1998).

Adverse maternal health outcomes, particularlyspontaneous abortions and haematological orchromosome changes, have been reported to oc-cur in certain populations exposed to RF fields.Some of these changes have also been reported inusers of video display units. Taken overall, thestudies in this area have not substantiated theseeffects (Repacholi, 1998).

8. Research needs

Through the international review processwhere scientists from every discipline were invitedto discuss gaps in knowledge, WHO has formu-lated its research requirements. Once this re-search is complete, the results will form a

database that can be used to conduct betterhealth risk assessments. In summary, the researchneeds are as follows.

RF research should concentrate on mobile tele-phones, working populations exposed to high lev-els of RF, and emerging technologies that useRF fields. There is a great need for very well-conducted epidemiological studies of mobile tele-phone users. One such study will be conductedby the WHO specialized agency for cancer re-search, the International Agency for Research onCancer (IARC). This study will be conductedsimultaneously in at least ten countries and deter-mine if mobile telephone use is associated withan increase in head and neck cancers. Other simi-lar epidemiological studies are underway toprovide much needed information in the area ofresearch.

Animal studies are needed where animals areexposed to RF fields simulating human exposuresituations. Of primary importance is to determinewhether RF fields can initiate, promote or pro-gress cancer. Many studies are currently under-way that address the cancer issue.

In addition to animal studies, it is possible totest human reactions to RF exposure in con-trolled laboratory studies. Here, healthy individu-als are exposed to RF fields to determine whetherthey are sensitive to these fields, suffer headachesor other subjective symptoms, or suffer changesin blood pressure, heart rate, or memory loss. Allthese effects are considered adverse and need tobe characterised and addressed in proper studiesthat further our knowledge in this area.

Studies are also conducted on cells, either in anutrient solution or as pieces of tissue. These arevery important for determining exactly how RFfields interact with living tissues. However, evenif an effect of RF exposure is found in thesecells, it does not necessarily mean that the sameeffect will occur in whole animals or humans.Once an effect is found, it still needs to be stud-ied further to determine if it has any adverseeffect in humans.

More details on RF research needs have beendescribed in WHO’s EMF research agenda(WHO, 1998) and is also available on the WHOweb site: www.who.int/emf.

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9. Current WHO recommendation on mobilephones and their base stations

A WHO fact sheet updating conclusions andrecommendations regarding health effects frommobile phone use and exposure to base stationswas published in June 2000 (WHO, 2000). Itstates that: none of the recent reviews have con-cluded that exposure to the RF fields from mobilephones or their base stations causes any adversehealth consequence. However, there are gaps inknowledge that have been identified for furtherresearch to better assess health risks. It will takeabout 3–4 years for the required RF research tobe completed, evaluated and to publish the finalresults of any health risks. In the meantime,WHO recommends the following.� Strict adherence to health-based guidelines. In-

ternational guidelines have been developed toprotect everyone in the population: mobilephone users, those who work near or livearound base stations, as well as people who donot use mobile phones.

� Precautionary measuresGovernment. If regulatory authorities haveadopted health-based guidelines but, becauseof public concerns, would like to introduceadditional precautionary measures to reduceexposure to RF fields, they should not un-dermine the science base of the guidelines byincorporating arbitrary additional safety fac-tors into the exposure limits. Precautionarymeasures should be introduced as a separatepolicy that encourages, through voluntarymeans, the reduction of RF fields by equip-ment manufacturers and the public. Detailsof such measures are given in a separate factsheet.Individuals. Present scientific informationdoes not indicate the need for any specialprecautions for use of mobile phones. Ifindividuals are concerned, they might chooseto limit their own or their childrens’ RFexposure by limiting the length of calls, orusing ‘hands-free’ devices to keep mobilephones away from the head and body.

� Obey local restrictions on mobile phone use toavoid EMF interference. Mobile phones may

interfere with certain electromedical devices,such as cardiac pacemakers and hearing aids.In hospital intensive care departments, mobilephone use can be a danger to patients andshould not be used in these areas. Similarly,mobile phones should not be used in aircraft asthey may interfere with its navigation systems.

� Driving safety. In moving vehicles, there is awell established increase in the risk of trafficaccidents while the driver is using a mobilephone, either a conventional handset or onefitted with a ‘hands free’ device. Motoristsshould be strongly discouraged from using mo-bile phones while driving.

� Simple protective measures. Fences or barriersor other protective measures are needed forsome base stations (principally, those locatedon building rooftops) to preclude unauthorisedaccess to areas where exposure limits may beexceeded.

� RF absorbing devices. Scientific evidence doesnot indicate any need for RF-absorbing coversor other ‘absorbing devices’ on mobile phones.They cannot be justified on health grounds andthe effectiveness of many such devices in reduc-ing RF exposure is unproven.

� Consultations with the community in sitingbase stations. Base station sites must offergood signal coverage and be accessible formaintenance. While RF field levels around basestations are not considered a health risk, sitingdecisions should take into account aestheticsand public sensibilities. Siting base stationsnear kindergartens, schools and playgroundsmay need special consideration. Open commu-nication and discussion between the mobilephone operator, local council and the publicduring the planning stages for a new antennacan help create public understanding andgreater acceptance of a new facility.

� Providing information. An effective system ofhealth information and communicationsamong scientists, governments, industry andthe public is needed to raise the level of generalunderstanding about mobile phone technologyand reduce any mistrust and fears, both realand perceived. This information should be ac-curate, and at the same time be appropriate in

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M.H. Repacholi / Toxicology Letters 120 (2001) 323–331 331

its level of discussion and understandable tothe intended audience.

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Lai, H., Singh, N.P., 1996. Single- and double-strand DNAbreaks in rat brain cells afteracute exposure to radiofre-quency electromagnetic radiation. Int. J. Radiat. Biol. 69,513.

Malayapa, R.S., Ahern, E.W., Struabe, W.L., Moros, E.G.,Pickard, W.F., Roti Roti, J.L., 1997a. Measurement ofDNA damage following exposure to 2450 MHz electro-magnetic radiation. Radiat. Res. 148, 608.

Malayapa, R.S., Ahern, E.W., Struabe, W.L., Moros, E.G.,Pickard, W.F., Roti Roti, J.L., 1997b. Measurement ofDNA damage following exposure to electromagnetic radia-tion in the cellular telecommunications frequency band(835.62 and 847.74 MHz). Radiat. Res. 148, 618.

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