EMFs at a glance

Electric and magnetic fields are produced wherever electricity is used. Electric fields are produced by voltage and magnetic fields by current.

Most people get most of their exposure from the distribution wires along the street and from wiring in the homes. We also get short-duration higher field exposures when we pass close to electrical appliances.

In the population as a whole, not many people live close (say within 100 m) of a high-voltage power lines. But for those who do, this will also be a significant source of exposure.

The UK Government set exposure limits for EMFs and the electricity system complies with these. The limits are designed to prevent all established effects of fields on the body.

However, there are suggestions that magnetic fields may cause other diseases, principally childhood leukaemia, at levels below these limits. The evidence for this comes from epidemiology studies, which have found a statistical association - an apparent two-fold increase in leukaemia incidence, from about 1 in 24,000 per year up to 1 in 12,000 per year, for the children with the top half percent of exposures. The evidence is strong enough for magnetic fields to be classified by the World Health Organization as "possibly carcinogenic". But because these studies only show statistical associations and do not demonstrate causation, and because the evidence from the laboratory is against, the risk is not established, it remains only a possibility.

See also WHO's 2007 short summary of the science

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