Power frequency electromagnetic fields and health. Where's the evidence?

Twenty years ago concerns were raised that exposure to power frequency (or extremely low frequency (ELF)) electromagnetic fields (EMFs) may be associa ted with an increased risk of cancer or other health hazards. Subsequently no associations have been shown between laboratory magnetic field exposures and carcinogenesis in either animal or cellular models. Indeed, studies ha ve demonstrated that magnetic fields are not associated with cancer. Howeve r, the puzzle remains that the results of some epidemiological studies may be interpreted as suggesting that living close to high-voltage transmission (HVT) lines appears to increase slightly the risk of childhood leukaemia. Alternatively, these results could result from small biases and errors in i ndividual studies, which might not necessarily be the same in each study. T he nature of the epidemiological studies (power line, wire code, magnetic f ield or appliance based) appears to determine whether and how the EMFs asso ciated with HVT lines might be a risk factor. It is possible that a simple association with either magnetic or electric field exposure may not be the whole answer, and an alternative mechanism is always a possibility. Althoug h the interpretation of the available evidence by most expert bodies has le d them to conclude that exposure to power frequency electric and magnetic f ields is not a human health hazard, a working group under the auspices of t he US National Institute of Environmental Health Sciences (NIEHS) concluded that there was a possible low risk associated with certain exposures to EL F magnetic fields. NIEHS itself interpreted the finding as insufficient to warrant aggressive regulatory concern but stated that, because virtually ev eryone is routinely exposed to ELF EMFs, passive regulatory action is warra nted, such as a continued emphasis on educating both the public and the reg ulated community on means aimed at reducing exposures. These analyses, conc lusions and advice are not contradicted by subsequent studies, and therefor e the conclusion of the World Health Organisation that further research is needed seems valid.