Exposure to extremely low frequency magnetic fields among working women and homemakers

Abstract

Given concerns with potential health effects of exposure to magnetic fields, the goal of this study was to examine the magnitude and sources of occupational and residential exposure to extremely low frequency (primarily 60 Hz) magnetic fields among women. Exposure to 60 Hz magnetic fields was surveyed among cases and controls recruited for a study of breast cancer in 25 counties in North Carolina. The 273 women who participated wore an integrating personal magnetic-field exposure meter (AMEX 3-D) that measured their time-weighted average (TWA) exposure. A questionnaire was administered to determine the duration and frequency of electric appliance and machinery use. The geometric mean (GM) of the TWA exposure for employed women was 0.138 μT (range 0.022–3.636 μT) and for homemakers 0.113 μT (range 0.022–0.403 μT). Women working in manufacturing and industrial facilities had the highest exposure (GM 0.265 μT, range 0.054–3.436 μT), while nurses and health technicians (GM 0.134 μT, range 0.032–0.285 μT) and teachers and school administrators (GM 0.099 μT, range 0.035–0.673 μT) had the lowest exposures. Job titles, unless very limited in scope and/or environment, self-reported information about equipment use, potential exposure sources, time, and distance were not good predictors of magnetic-field exposure. Furthermore, the results show that occupations previously observed to have increased risk of breast cancer, such as teachers, nurses, administrative support, and housewives, did not have elevated average magnetic field exposures. Therefore, it is questionable whether exposure to power frequency magnetic fields is the cause of the increased breast cancer risk seen in these occupations.