Abstract
The principal aim of the meeting as advertised was to review the current state of knowledge of the effects of electromagnetic radiations specifically at levels to which the general public are routinely exposed. The meeting was well attended with over 100 representatives from a whole spectrum of backgrounds; general industry, the defence sector (MOD, DERA, RN), the medical profession, academia, the power industry (National Grid) and many others. Professionals in the field will be only too aware of the rise in media attention, with headlines such as `Mobile phones fry your brain cells' creating significant public unease and disquiet. My own personal interest in attending was to determine whether any new hard evidence for harmful biological effects at low level EMF exposure had been uncovered of which I was unaware.
Alastair McKinlay (NRPB), in his introduction, discussed amongst other things the interesting question of who determines proof of causality: the scientist or the lawyer? Recent court cases have highlighted only too well the difference between the scientific and legal professions in the interpretation of scientific evidence and the phrase `beyond reasonable doubt'. We were then given an overview for the day with a comprehensive review of the sources and levels of typical EMF exposures and the current standards in existence (Stuart Allen, NRPB). It was clearly emphasised that the public are rarely, if ever, in a position to be exposed at EMF levels in excess of the relevant standards. This was followed by an outline of the WHO international EMF project (Arwel Barrett, HSE). The aim of the project is to set up a `wise council' responsible for review of all the current research in order to provide authoritative advice on the identified health risks, determine gaps in our knowledge and direct new research towards these gaps.
Subsequent speakers discussed the principles of measuring EMFs and the typical problems encountered in their own particular areas of concern. When making measurements from power lines it must be remembered that the electric field is very susceptible to perturbation, not only from the presence of the surveyor and any inquisitive cows, but also potentially from the insulated equipment stand, depending on the weather conditions. Moisture deposited along the surface of an insulated pole will create a conductive path that may significantly perturb the measured electric field depending on the stand geometry used. Considerable debate was generated in relation to the appropriate methods for measurements of EMFs in the home: is electric field or magnetic field important, where should the measurements be made, is field polarisation important? Since no relationship between EMF exposure and risk of cancer has been established to date, no mechanism for cancer induction has been identified, and to some extent there is no basis for deciding what to measure.
After a very pleasant lunch we were treated to the `meat' of the meeting: three presentations covering the latest evidence from cellular, animal and epidemiological studies respectively. The consensus view that ran through the first two talks was that, although a relatively large number of papers have been published which claim positive responses between EMF exposure and some biological effect, these results do not stand up to rigorous scientific scrutiny. Attempts by independent laboratories to replicate the experimental results have invariably failed, although one positive animal response has been reproduced. However, the observed response is memory related and seems to have no long-term effect. The last speaker of the session (Ray Cartwright, Leeds University) gave an examination of the findings of the more rigorous epidemiological studies that have been carried out. However, it seems that even the epidemiological community realise that they are good at producing results that cannot be explained, and the conclusion reached was that the results of current studies are complex, confusing and conflicting at best. The overall conclusion to which we were drawn is that if EMFs do cause cancer then the quantitative effect must be very small.
The use of EMFs in the medical profession was outlined in the first talk of the final session (Tony Barker, Royal Hallamshire Hospital). Most real applications rely on thermal effects (hyperthermia for the treatment of tumours, short wave diathermy in physiotherapy) although an interesting non-thermal effect has recently been described which has produced encouraging results in the treatment of depression. The meeting was concluded with two presentations in which were discussed media sensationalism of the issues discussed throughout the day, and how to bridge the gap between the expert's (objective) and lay persons' (subjective) perceptions of risk.
This meeting was wide ranging in its examination of the subject of low level EMFs, from which the conclusion can be drawn that with respect to risk of cancer and other harmful biological effects there are still no firm conclusions - a situation that seems to have remained static over the last few years. Although there is little evidence, if any, to support an influence on cancer as a result of EMF exposure, the salient point as far as the media are concerned will undoubtedly be that the antithesis remains unproven.
Colin Scott