RESIDENTIAL EXPOSURE TO MAGNETIC-FIELDS AND ACUTE LYMPHOBLASTIC-LEUKEMIA IN CHILDREN

Background Previous studies found associations between childhood leuke mia and surrogate indicators of exposure to magnetic fields (the power -line classification scheme known as ''wire coding''), but not between childhood leukemia and measurements of 60-Hz residential magnetic fie lds. Methods We enrolled 638 children with acute lymphoblastic leukemi a (ALL) who were under 15 years of age and were registered with the Ch ildren's Cancer Group and 620 controls in a study of residential expos ure to magnetic fields generated by nearby power lines. In the subject s' current and former homes, data collectors blinded to the subjects' health status measured magnetic fields for 24 hours in each child's be droom and for 30 seconds in three or four other rooms and outside the front door. A computer algorithm assigned wire-code categories, based on the distance and configuration of nearby power lines, to the subjec ts' main residences (for 416 case patients and 416 controls) and to th ose where the family had lived during the mother's pregnancy with the subject (for 230 case patients and 230 controls). Results The risk of childhood ALL was not linked to summary time-weighted average resident ial magnetic-field levels, categorized according to a priori criteria. The odds ratio for ALL was 1.24 (95 percent confidence interval, 0.86 to 1.79) at exposures of 0.200 mu T or greater as compared with less than 0.065 mu T. The risk of ALL was not increased among children whos e main residences were in the highest wire-code category (odds ratio a s compared with the lowest category, 0.88; 95 percent confidence inter val, 0.48 to 1.63). Furthermore, the risk was not significantly associ ated with either residential magnetic-field levels or the wire codes o f the homes mothers resided in when pregnant with the subjects. Conclu sions Our results provide little evidence that living in homes charact erized by high measured time-weighted average magnetic-field levels or by the highest wire-code category increases the risk of ALL in childr en. (C) 1997, Massachusetts Medical Society.