Sunday, December 24, 2006

Mobile Telephones And Health Effects

Introduction:
Mobile telephones have transformed the telecommunications industry. These devices can be used to make telephone calls from almost anywhere. There are two types - the normal mobile phone has the antenna mounted on the handset and the other has the antenna mounted on a separate transmitter or, if the phone is installed in a vehicle, mounted on the roof or rear window. Communication between a mobile phone and the nearest base station is achieved by the microwave emissions from the antenna. Only the normal mobile phone is considered here.
Basis of Health Concerns:
Concerns have been raised about the normal mobile phone, which has the antenna in the handset. In this case, the antenna is very close to the user's head during normal use of the telephone and there is concern about the level of microwave emissions to which the brain is being exposed.
Those telephones that have the antenna mounted elsewhere are of no concern, since exposure levels decrease rapidly with increasing distance from the antenna. Cordless telephones, which need to be operated within about 20 meters of a base unit that is connected directly to the telephone system, do not have any health concerns associated with their use because exposure levels are very low.
Reports have appeared in the media linking the use of mobile telephones with, among other things, headaches, hot spots in the brain and brain cancer.
Media reports have claimed that up to 70 percent of the microwave emissions from hand-held mobile telephones may be absorbed in the user's head. This is not supported by the evidence, but nevertheless leads to speculation that hot spots may be created in the user's brain, thereby raising concerns that the telephones may be a health risk. Other reports have indicated that mobile telephone users suffer localized headaches when they use their telephone. At this stage, it is difficult to evaluate the evidence supporting these reports, since they have not been published.
The brain cancer reports originated in the USA where a number of lawsuits have been lodged against mobile telephone manufacturers and suppliers. These claims for damages allege that the microwave emissions from mobile telephones used by the claimants caused their (in some cases, fatal) brain cancers. Those few cases that have been tried have been dismissed for lack of supporting evidence.
Known Effects of Microwave Exposure:
Microwaves are but one type of electromagnetic field. (For the purposes of this Information Bulletin, "fields" and "radiation" are equivalent.) One of the ways that these fields are described is by specifying their frequency. The range of frequencies that are useful for telecommunications include microwaves.
Some public concern about mobile telephones is erroneously based on media attention to the possibility of adverse effects from exposure to power-line electromagnetic fields, which have a much lower frequency than the microwaves emitted by mobile telephones. The physical properties and biological effects of these fields are very different from microwaves and it is meaningless to extrapolate the results of those studies to the subject of this Information Bulletin.
The ARPANSA Radiation Protection Standard "Maximum Exposure Levels to Radio frequency Fields - 3kHz to 300 GHz " is based on the well-established thermal effects of exposure to microwaves. That is, when tissue is exposed to sufficiently high levels of microwaves, the tissue is heated and damage may occur. The exposure limits are set well below levels where any significant heating occurs. The Standard also sets limits for pulsed radiation that are intended to eliminate possible effects where heating is not evident (non-thermal effects).
All mobile telephones marketed in Australia must satisfy the regulatory requirements of the Australian Communications and Media Authority (ACMA), as well as that part of the Australian Standard that sets limits on the power output of a mobile telephone. Therefore, use of a mobile telephone is not expected to cause significant heating in any part of the body, including the brain.
Some research has indicated that non-thermal effects resulting from low-level microwave exposure may also occur. However, the existence of these effects and their implications has not been sufficiently established to allow for them in the Standard.
Uncertain Evidence of Cancer:
A few animal studies suggest that exposure to weak microwave fields can accelerate the development of cancer. Further studies are required to establish their reproducibility and the existence or otherwise of a dose-response relationship. Whether these results are relevant to users of mobile telephones is not clear. In any event, these results cannot be dismissed at this stage.
The very few studies that have been conducted on human populations (epidemiological studies) do not provide any direct information on possible mobile telephone hazards and hence are of limited value. The results of these studies are difficult to interpret because exposure levels were either not measured or impossible to determine from the data provided. In general, however, this type of study will be useful in identifying possible links between mobile telephone use and cancer risk. Complementary cellular and animal research is required to establish any cause-and-effect relationship and the biological mechanisms involved.The Australian Radiation Protection and Nuclear Safety Agency continues to closely monitor the research being conducted in this area.
On the specific issue of brain cancer occurring in users of these telephones, it is important to note that such cancers existed before the introduction of mobile telephones. It is simply not possible to identify the cause of any single case of cancer. Long-term studies to investigate whether mobile telephone users have a greater incidence of, say, brain cancer than the general population have not been completed.
Government Research Funding:
Commencing in 1996, the Government provides $1 million dollars per annum for the Electromagnetic Energy (EME) Program. This program supports research into and provides information to the public about health issues associated with mobile phones, mobile phone base stations and other communications devices and equipment. The program recognises public concern, and the need to ensure standards and public health policies continue to be based on the best available scientific information.
The EME program is coordinated by the Committee on Electromagnetic Energy Public Health Issues (CEMEPHI), which includes representatives from the Department of Communications, Information Technology and the Arts, the Department of Health and Ageing, ARPANSA, the ACMA, and the National Health and Medical Research Council (NHMRC). The program has three elements:
  • an Australian research program (managed by the NHMRC) to conduct research into EME issues of relevance to Australia and to complement overseas research activities;
  • Continuing Australian participation in the World Health Organization's (WHO) International Electromagnetic Field (EMF) Project which assesses the health and environmental effects of EME exposure, and;
  • A public information program (managed by ARPANSA) to provide information to the public and the media.

Conclusion:

There is no evidence that microwave exposure from mobile telephones causes cancer, and inconclusive evidence that such exposure accelerates the growth of an already-existing cancer. More research on this issue needs to be carried out.

Users concerned about the possibility of health effects can minimize their exposure to the microwave emissions by: limiting the duration of mobile telephone calls, using a mobile telephone which does not have the antenna in the handset or using a 'hands-free' attachment.

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