Power lines, viruses, and childhood leukemia

Abstract

Mr Sahl hypothesizes' in the May (5:3) issue of CCC that viral contacts may explain reported associations between childhood leukemia and residential proximity to high voltage power lines. Although a viral etiology of leukemia has been of interest for some time2 and warrants more refined study, it seems unlikely that confounding from viral exposures has an impact on the reported associations between magnetic fields and cancer or that the literature on wire codes and magnetic fields has relevance to the viral hypothesis. Before addressing his key argument, some clarification is necessary: (i) Studies of childhood cancer and residential magnetic fields are not concerned, with the exception of the Nordic studies,3 with exposure from hightension power lines. Studies in urban communities4 are based on whatever types of power lines are near the home, with virtually all classified based on nearby, ordinary low-voltage distribution-lines. A more refined wire code7 gave less, not more, emphasis to the few homes near high tension lines since High Wire Code comprised a broader group than the Very High Current Configuration category used in previous studies; (ii) While the cancer associations based on wire codes have been stronger than those based on measured fields, there are theoretical reasons (accurately stated by Mr Sahl) that make the superiority of one versus the other as a marker of historical exposure uncertain. It should be noted that no study, to date, has had a sufficiently comprehensive set of field measurements to provide strong evidence for or