Population based case-control study of occupational exposure to electromagnetic fields and breast cancer

PURPOSE: This population-based case-control study examined occupational exp osure to electromagnetic fields in relation to female breast cancer inciden ce among 843 breast cancer cases and 773 controls. METHODS: Exposure was classified based on work in the two longest-held jobs , and indices of cumulative exposure to magnetic fields based on a measurem ent survey. RESULTS: Female breast cancer was not associated with employment as an offi ce or industrial worker. For the total study population, cumulative exposur e over the entire career, and in the past 0-10 and 10-20 years generally sh owed odds ratios (ORs) close to the null. Moderately elevated risks were fo und for inter mediate but not high levels of cumulative exposure accumulate d 20 or more years ago (OR = 1.5; 95% CI = 1.1-2.0). Associations were stro nger for premenopausal women (OR = 1.7; 95% CI = 1.1-2.7) in the past 10-20 years, and those with estrogen-receptor positive (ER+) breast tumors (OR = 2.06; 95% CI = 1.1-4.0). No consistent dose-response patterns were observe d. CONCLUSIONS: These findings give little support to the hypothesis that elec tromagnetic fields cause cancer of the female breast. Ann Epidemiol 2001; 1 1:297-303. (C) 2001 Elsevier Science Inc. All rights reserved.