Influence of power frequency electric and magnetic fields on human health

Several reports have appeared in the last ten years in which the authors suggest an association between cancer/leukemia and exposure to electric and magnetic fields in the workplace or in the vicinity of distribution lines from overhead transmission systems. Several of these reports are reviewed and critiqued. The reports of clinical effects of electric and/or magnetic fields among human populations present serious difficulties which stem from the many publications in which pertinent material is not presented, and the data are variable or internally inconsistent. The reports presented so far are not very probing. The numbers of subjects are small, the epidemiologic methodologies are often weak, measurements of intensity of field are absent, and the statistical analyses utilized are not always appropriate. Although suggestive associations of electric/magnetic fields and cancer or leukemia have been made, no one has established a causal relationship between these fields and cancer or leukemia. All the reports on human exposure have numerous deficiencies which include: lack of or imprecise measurements of electric or magnetic field intensities, questionable subject identification, lack of statistical significance, confounding with uncontrolled variables such as socioeconomic differences, smoking, X rays, drugs, population mobility, and the unreliability of occupational classification. Nevertheless the possibility of a link between leukemia and cancer and exposure to electric and magnetic fields has been raised and only responsible research can refute or confirm these reports.