A perspective on electromagnetic field bioeffects and risk assessment

Abstract

There is evidence to suspect that a human health risk could exist from exposure to power frequency electromagnetic fields (EMFs). Summary analyses of epidemiological evidence suggest that, if the effects seen are real, they are small, with relative risks of the order 1.5–2.5. The past several years of epidemiological results are consistent with those of previous years, but do not add markedly to the understanding of potential human health risk. A similar situation has existed with benzene. Health concerns for benzene originated in the workplace with case reports. For many years, epidemiology studies alone provided the information on risks from benzene; until recently, animal models did not yield any tumors. Finally after 50 years of laboratory studies, an animal model provided tumors, but not the primary one associated with benzene exposure to humans. A brief history of the benzene story is presented to provide a perspective on the progress in understanding the potential risk of EMFs. Radon and toxic chemicals, which are present in indoor air, have been examined qualitatively only in a few EMF epidemiological studies. Because these materials have the potential to overshadow any signal coming from EMF exposures, they must be treated quantitatively. No classical cancer studies have been completed as yet for EMFs, but a variety of promotion or copromotion animal studies have been reported. Results of these and other studies lend support for consideration of EMF not being a complete carcinogen, but possibly a promoter. Qualitatively, whole animal studies, together with results of epidemiological works, suggest that greater intensities (magnetic flux densities) may be associated with greater responses (or lower p values). Other laboratory studies have been designed to examine more basic mechanisms, but the use of these types of studies in risk assessment is not straightforward. A methodology, based on relative potency concepts, is introduced; it can be used to assist in the assessment of the degree of hazard which EMF poses. EMF researchers can contribute to the use of this type of analysis by including positive controls in their experimental designs.