CANCER MORBIDITY AMONG EMPLOYEES IN A DANISH PHARMACEUTICAL PLANT

Background. Workers in the pharmaceutical industry may be exposed to m any potential carcinogens. We investigated cancer morbidity in a Danis h plant where enzymes, insulin, antibiotics and sex hormones were prod uced in substantial quantities. Methods. Altogether 10889 people ever employed (1964-1988) at the pharmaceutical plant were retrieved from t he files of a compulsory pension fund, and followed-up in the nationwi de Danish Cancer Registry (1964-1989). Site-specific standardized inci dence ratios (SIR) were estimated, based on cancer rates for the natio nal population. information on risk factors for breast cancer, e.g. nu mber of children, age at menarche and first delivery, obesity, and non -occupational use of sex hormones was obtained from samples of the fem ale employees, and compared to equivalent variables from the general p opulation. Results. The overall SIR for women was significantly elevat ed (n = 5554; SIR = 1.2). Excess risk was particularly seen for breast cancer (n = 97; SIR = 1.5), especially in a subgroup who had started work at the factory aged 30-39 and had continued to work for 1-9 years (SIR = 2.8). The SIR was near unity for men (n = 5335); however, thre e men with breast cancer versus 0.4 expected were found. Lifestyle com ponents explained only about one-quarter of the excess female breast c ancers. Proxy measures of intensity of occupational exposure to sex ho rmones or insulin showed no association with the risk for breast cance r. Conclusions. It seems unlikely that either a single occupational fa ctor or an unusual reproductive pattern can explain the elevated breas t cancer risk. Therefore, the finding requires further study.