Occupational exposures associated with male breast cancer.

The role of occupational exposure to heat and electromagnetic fields was investigated in a case-control study of male breast cancer. Seventy-one cases reported to the New York State Tumor Registry between 1979 and 1988 were compared with 256 healthy male controls. Controls were frequency matched to cases by race, year of diagnosis, and age in 5-year intervals. Unconditional logistic regression modeling indicated that males with occupations that involved heat exposure had an elevated risk for the disease. The age- and county-adjusted odds ratio was 2.3 (95% confidence interval (CI) 0.95-5.3). Exposure to heat on the job could influence testicular function. No increase in disease risk was observed for males believed to have occupational exposure to electromagnetic fields (odds ratio = 0.7, 95% CI 0.3-1.9).