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Mobile phones and health: an interim report

2001

Possible adverse health effects
Guidelines
To prevent adverse health effects from heating by radiofrequency radiation, guidelines have been established that limit the exposure to members of the public. These guidelines set out the “basic restrictions” on the amount of energy that can be safely absorbed by a given mass of body tissue, and are called SAR (Specific Absorption Rate – watts per kilogram, Wkg -1 ).

Unfortunately, it is not easy to measure SARs in living people, and so “investigation levels”, eg power density in watts per square metre (Wm -2 ), may be used instead to indicate radiation exposure levels.

Sets of SAR guidelines and “investigation levels” have been produced by the UK National Radiological Protection Board (NRPB)(18) and an international body of experts, called the International Commission on Non-ionising Radiation (ICNIRP),(19) whose recommendations have been accepted by the EU Council.(7)

The NRPB guidelines and “investigation levels” relate to all people, whereas the ICNIRP guidelines and “investigation levels” distinguish between public and occupational exposure.

The limits for occupational exposure are similar to those recommended by the NRPB, but those for the public are five times lower, on the basis that whilst occupational exposure can be controlled, that for the public is uncontrolled and cannot be monitored.

The House of Commons Select Committee on Science and Technology(10) recommended, and the Government agreed, that the ICNIRP limits should be adopted in the UK “as a precautionary measure”.

The NRPB argues that there is no conclusive scientific evidence to support lowering the SAR levels, but all modern digital mobile phones (and most base stations) comply with the ICNIRP guidelines already.

There is evidence to suggest that even below these restrictions there are biological effects, although there is a need to distinguish between those that result in an adverse health effect, and those that do not.

Those effects that are not due to heating are called ‘non-thermal’. The NRPB does not consider that there is sufficient evidence for these effects to justify considering them in its guidelines for maximum exposure, although the UK Science and Technology Select Committee recommended that the NRPB should regularly review the scientific evidence for them.

There are various hypotheses relating to the mechanisms for non-thermal effects (see Stewart Report,(3) chapter 5, for in-depth analysis). These include changes in cell membranes, effects on the blood-brain barrier, and attraction between neighbouring cells.

Concerns about the possible health effects cover a variety of conditions and a number of reports review the evidence for these.(3,4,8,9)

Below is a summary of the recommendations to date for some of these conditions – readers should consult the reports for full details of these and other conditions. Evidence is derived from in vivo and in vitro experiments, and dosimetry studies.

Difficulties are encountered since many studies of radiofrequency radiation (RFR) are not specific to that generated by mobile phone technology, they may cover whole-body exposure rather than local exposure, and they vary in the intensities and levels of exposure investigated and are thus not comparable.

Cancer
Since RFR is non-ionising (ie cannot break down bonds between atoms), it is unlikely that it could directly induce a carcinogenic process, however, there is anxiety that it might possibly promote or progress it.

The consensus is that current scientific evidence indicates that exposure to RF fields is unlikely to induce or promote cancers.(3,5,8,20,21) Those studies that have found positive results(22) require replication and their applicability to humans needs to be evaluated.

There have been reports of DNA fragmentation which could be relevant to malignancy(23) but these have not been confirmed independently and are subject to much dispute. The International Agency for Research into Cancer is conducting a study that aims to address these uncertainties (see table on page 8).

Reproductive system
Since developing embryos or foetuses are vulnerable to environmental hazards at lower levels than adults, assessing the possible effects of RF fields on fertility and development should be a priority area.

The Stewart Group concluded that studies on rodents have not found any convincing evidence of risks to the foetus or male fertility, but one study(24) of female rodents found a decline in their fertility at low level RF exposure. The Group recommended this study be repeated under controlled conditions (absent in the original study) so that conclusions can be drawn.

Effects on the eye
The eye has limited capability to dissipate heat and is not protected by bone like the brain. Hence, the Royal Society of Canada(8) has concluded that the possibility of adverse effects to the eye by RFR should be treated with caution and concern.

Studies have demonstrated that high level (thermal) exposure to RFR may produce adverse effects in the eye, particularly in the retina, iris and cornea, although no definitive conclusions can be reached since the studies have used intensities of pulsed RF fields “well above the SAR and specific absorption that could occur in the eye from the use of current mobile phones”.(3)

Cognitive effects
There has been concern that RFR may effect cognitive functions such as memory, reaction times, and sleep processes. One study has reported a decrease in reaction times in people exposed to RFR,(25) a finding that has been replicated by an independent group.(26)

The same study failed to find evidence for memory loss or attention deficiency. Hydration levels were not considered to be a confounding factor.(27) Studies on sleep processes have demonstrated that exposure to RFR both before and after sleep onset enhances the intensity of the brain’s electrical signals (EEG) during sleep.(28, 29)

Other studies have concluded that RFR exposure may shorten the time to sleep onset,(30) and may reduce the amount of waking after sleep starts.(29) The NRPB writes that the few studies that have investigated these issues do not suggest the existence of an obvious health scare.

Children
Children are amongst the keenest users of mobile phones: ownership levels are now at 16% for primary school children and almost 59% for secondary school children in England, Wales and Northern Ireland.(31)

Due to their developing nervous systems, greater absorption of energy in the tissues of the head, and their longer lifetime exposure, children may be more vulnerable to the effects of RFR.

Unfortunately, the epidemiological studies that have focused on children and their reactions to electromagnetic radiation have been ecological in design, lacking any individual level data for either exposure or potential confounders.(8) Consequently these studies are not particularly informative about potential RF health risks.

The Stewart Report(3) advised that children under 16 years of age should be discouraged from using mobile phones for non-essential calls, and in addition, that the mobile phone industry should refrain from promoting the use of mobile phones by children.

Children are particularly likely to use mobile phones for text messaging, a use that has increased exponentially, with over 900 million messages being sent in the UK in January 2001 alone.(32)

Since the handset is normally held near to waist level for this activity, research is necessary into whether mobile phone radiation may effect different parts of the body in different ways, and hence whether there are any additional possible health risks associated with text messaging.

Subjective disorders
Mobile phone users have complained of short term adverse effects including headaches, dizziness, and unpleasant heating or tingling in the head or behind the ear.(33)

One epidemiological study suggested that users experienced such symptoms in a dose dependent fashion, with symptoms increasing with greater phone use.(34) There have been very few studies that have looked systematically at such users, so firm conclusions cannot be drawn, although one review(8) concluded that existing evidence does not support the conclusion that microwave radiation (part of RFR) can induce headaches.

To end the uncertainty, the Stewart Report(3) recommended that a large cohort study of long term mobile phone users be conducted in the UK, that double-blind studies be undertaken to assess the relationship between mobile phone use and these symptoms, and a significant research programme be initiated so that “the impact of mobile phone technologies on well-being in its broadest sense” can be determined.

Base stations
Base stations may contain more than one transmitter and the outputs of each transmitter are fed to the antenna on top of the mast. Each transmitter gives rise to a maximum radiated power of approximately 10W at the antenna and each base station may have up to 8 transmitters – thus maximum powers radiated from the antenna are in the region of 80W. The antenna are located up to 50m above ground level and the main RF beam is angled slightly downwards so that it reaches ground level typically between 50 and 300m from the foot of the mast (see figure 2).

Hence, whilst exposures close to the antenna and directly in front of the beam can exceed guidelines, power density decreases with distance from the antenna and calculations have shown that exposure levels fall below NRPB and ICNIRP public guidelines at distances greater than 3.1m and 8.4m respectively.(13) There is, nevertheless, a practice, and recommendation by the Stewart Group, of defining and marking exclusion zones around the antennas.

The NRPB measured radiowave signal strengths at 118 locations of public access near base stations and found that the maximum exposure at any location measured was 0.023% of the NRPB guideline and 0.18% of the ICNIRP reference level.

The exposures were therefore well within the guidelines and not considered hazardous. This included exposure to signals from other sources, eg radio, TV and pagers; however, such exposures were found to be very variable, and could make it difficult to isolate the health effects of signals from base stations in any population-based epidemiological study.

A base station measurement audit and database recommended by the Stewart Group is being taken forward by the Radiocommunication Agency of the Department of Trade and Industry to ensure that exposures of people in the vicinity of them are within guidelines. It is anticipated to be ready and on-line by summer 2001.(35)

The Stewart Report(3) concluded “the balance of evidence indicates that there is no general risk to the health of people living near to base stations on the basis that exposures are expected to be small fractions of guidelines.

However, there can be indirect effects on their well-being in some cases”, such as anxiety about the possible effects, or possibly a reduction in the value of property. In terms of schools, it has been recommended that the beam of greatest intensity from the masts should not fall on the site without the agreement of the school and the parents, and it should be recognised that exposure may be less with a mast placed on top of the buildings due to the way the RF waves spread out.

Further research
Research is being conducted on a worldwide scale, largely according to the WHO agenda for further research (www.who.int/peh-emf), and individual countries and academic researchers are contributing to the larger scale programmes.

The WHO has established an on-line research database (www.who.int/peh-emf/database.htm) which contains details of published and on-going research. The UK Department of Health has established a multi-million pound programme of research that will be 50% funded by industry.

An independent panel of experts will co-ordinate the research. The following table summarises the main programmes, and individual UK projects that are contributing to these.

Summary
The most recently published reviews of the literature have concluded that whilst there are small physiological effects within the existing guidelines, there are no definite adverse health effects from mobile phones or their base stations.

However, all the main professional organisations have called for more research to be conducted, since the possibility that radiofrequency radiation may cause adverse effects cannot be ruled out on the currently available data.

Clearly there are large gaps in the knowledge that need to be addressed. The Stewart Group recommended the precautionary approach be adopted until more detailed and scientifically robust information on any health effects becomes available, and the WHO listed recommendations for countries to follow until the conclusive research is published in 2-3 years time.

The table (below) details the current on-going and planned research.

Currently planned and on-going research into possible adverse effects of mobile telephone technology

Organisation	Research details	Funding details available	Estimated completion
World Health Organization (WHO)	The International EMF project aims to initiate and co-ordinate research worldwide into the possible health effects of EMF including RF fields emitted by mobile phones and their base stations to produce a well-founded response to public concerns.   Collaborating organisations include 8 international agencies, over 40 national authorities, and 8 WHO collaborating centres. The research agenda is available on www.who.int/peh-emf/database.htm	US$600,000 per year	2005
International Agency for Research into Cancer (IARC)	Co-ordinating a multi-national case control study to identify whether there is a link between mobile phone use and cancer of the brain and salivary glands. There are 13 countries involved including the UK.	Funded by WHO and a grant from the EU	2004
Leukaemia Research Fund Centre, Leeds University	Multi-centric UK case control study of the aetiology of adult brain tumours. Its aim is to test a number of hypotheses associating brain cancers with exposure to various agents including the use of mobile phones. This study will contribute to the IARC study.	EU funded	2004
Medical Physics University Research Centre, Bristol	The main objectives of the research are the dosimetry of the head from GSM mobile phones and examination of the mechanism of cognitive and other changes. Specific studies are:
	- Minimally invasive E-field dosimetry of target organs in a complex head phantom	£45,000 from DTI	Sept 2001
	- Effect of mobile phone radiofrequency exposure on the permeability of human placentas	£15,000 from charitable trustees and MRC	Sept 2001
	Three other projects are lodged with the Department of Health in conjunction with Burden Neurological Institute and National Physics Laboratory.
European Commission	Under the Fifth Framework Programme 1998-2002 Quality of Life Key Action 4, the following studies are being conducted:		All projects will be completed by 2004
	- Combined effects of electromagnetic fields with environmental carcinogens	980k euros
	- International case-control studies of cancer in relation to mobile telephone use (IARC)	3,850k euros
	- In vivo research on possible health effects related to mobile telephones and base stations (carcinogenicity studies in rodents)	2,050k euros
	- Risk evaluation of potential environmental hazards from low-energy electromagnetic field (EMF) exposure using sensitive in vitro methods	2,050k euros
	- Development of advice to the EC on the risk to health of pulsed electromagnetic fields	58k euros
National Radiological Protection Board (NRPB)	1. Development and application of anatomically realistic computational phantoms to measure the interaction of magnetic and electrical fields with the human body.
	2. Study to address the possible effects of RF radiation on the induction of chromosomal damage in human lymphocytes.
	3. UK National Study conducted jointly with the Institute of Occupational Health at Birmingham University to investigate occupational exposure to RF EMF and radiation from various sources including broadcast transmitters and telecommunications. Commenced November 1998	£600,000 industry contribution	2002
	4. A working group is examining the implication of the Stewart Report’s recommendation that ICNIRP guidelines are adopted for SAR.
UK Department of Health	An extensive research agenda including: effects on brain function; consequences of exposure to pulsed signals; improvements in dosimetry; the possible impact on health of sub-cellular and cellular changes induced by RFR; psychological and sociological studies related to mobile phone use; epidemiological and human volunteer studies including the study of individuals who might be more susceptible to RFR; emerging communication technologies (that is, 3G phones), including an epidemiological study of 3G users.	£7 million Government : industry 50 : 50	2004/5
Industry	UK cellular operators do not conduct their own scientific research. However, they set up a committee in 1999 (Scicom) to direct funding to research projects in the UK when approached by researchers.	50% of Department of Health’s programme	2004/5
	The worldwide GSM Association set up the Electromagnetic Compatibility and Bioeffects Review Committee to consider the research that should be funded by GSM members.	£3 million for the 5 years	2004/5