DO POWER FREQUENCY MAGNETIC-FIELDS CAUSE LEUKEMIA IN CHILDREN

The possibility of a causal relationship between exposure to electroma gnetic fields and childhood leukemia has been studied for more than 10 years. This review evaluates the epidemiologic findings relevant to a possible causal association between exposure to power frequency magne tic fields during childhood and leukemia. The nine published studies o n this topic were analyzed, with a focus on the selection of subjects, assessment of exposure, and control of confounding. Consistency of a positive association and dose-response relationship are evident for as sessment of past exposure: among the five recent studies, relative ris k estimates vary from 1.5 to 2.7 for past exposure assessment, and a s ignificant dose-response relation was found in three studies. These ob servations cannot be explained by misclassification of exposure or con sistent selection bias, and a confounder effect could hardly explain s uch results. Even if there is no currently understood biological plaus ibility for such an association, its possible causal nature cannot be dismissed. The impact on public health of such a possible causal assoc iation is difficult to assess precisely but could be significant, Ther efore, it might be prudent to consider interim preventive measures whi le we await results of further research.