60 Hz EMF health effects-a scientific uncertainty

Extensive epidemiological and laboratory research has been conducted over the last 15 years on the biological and health consequences of exposure to ELF EMFs. Some epidemiological studies have found weak associations between exposure to power-frequency EMFs and some forms of cancer, such as leukemia; while other studies have failed to find such associations. The primary limitation with most epidemiological studies has been with the methods of exposure assessment. Rigorous methods of exposure assessment that can be associated with biological effects are clearly needed. Epidemiological studies also continue to suffer from significant methodological difficulties associated with the effects of confounding factors. These difficulties hinder interpretation and acceptance of epidemiological findings. Laboratory studies have noted a wide variety of interesting biological effects resulting from exposure to power-frequency EMFs. The most significant and replicated findings are an apparent change in ion efflux at cell membranes in response to limited ranges and intensities of ELF electric fields, an effect of ELF magnetic fields on melatonin production, and effects on enzyme activity. Several concerns exist with regard to the laboratory findings. One concern is that the field strengths used are often orders of magnitude greater than commonly encountered in the home or office. Another concern is that much of the laboratory evidence remains to be independently confirmed. Lastly, a credible mechanism by which commonly encountered (milligauss) power-frequency EMFs could produce human health effects such as cancer still needs to be developed. Thus, the significance of the laboratory findings to human health is questionable. Though the evidence on ELF EMF health effects is mixed, it cannot be dismissed out of hand