Exposure to power frequency magnetic fields and risk of breast cancer in the Upper Cape Cod Cancer Incidence Study

Investigators used a population-based case-control study to evaluate the relationship between breast cancer risk and exposure to 60-Hz magnetic fields from various sources. There was no increase in breast cancer risk associated with (a) holding a job with high (odds ratio [OR] = 1.2; 95% confidence interval [CI] = 0.4, 3.4) or medium (OR = 0.9; 95% CI = 0.5, 1.7) exposure to magnetic fields; (b) living in a home heated electrically (OR = 1.0; 95% CI = 0.7, 1.4); or (c) sleeping with an electric blanket (OR = 1.0; 95% CI = 0.7, 1.4). There was a nonsignificant 50% increase in risk for subjects who lived within 152 m (500 ft) of an electricity transmission line or substation (OR = 1.5; 95% CI = 0.6, 3.3). Although limited by small numbers and exposure misclassification, the data in this study did not support the hypothesis that exposure to 60-Hz magnetic fields increases the risk of breast cancer in women.