Moulds, bacteria and cancer among Finns: an occupational cohort study

Abstract

Background: Some environmental moulds and bacteria produce carcinogenic toxins. Aim: Our objective was to study associations between work-related exposure to moulds and bacteria and cancers in Finland. Methods: We followed up a cohort of all economically active Finns in the population census in 1970 for 30 million person-years. Subsequent cancer cases were identified through a record linkage with the Finnish Cancer Registry. Observed and expected numbers of cancer cases were calculated by occupation, sex, birth cohort, and calendar period. Exposures to moulds of agricultural and industrial origin and to bacteria of nonhuman origin were estimated with the Finnish Job-Exposure Matrix. Results: Men with the highest mould and bacteria exposure had a reduced relative risk for lung cancer (RR 0.7, 95% confidence interval 0.6-0.9). Women in the highest mould and bacteria exposure category had RRs of 3.1 (1.0-9.2) and 2.6 (1.5-4.7) for cervical cancer, respectively. The respective RRs for lip cancer were 2.4 (1.2-5.1) and 1.6 (1.2-2.2). Conclusions: Exposures at investigated concentrations to either moulds or bacteria are unlikely to be major risk factors of cancer, although suggestions of risk increases were observed for some cancer types. It has earlier been suggested that the decreased risk for lung cancer is due to the protective effect of endotoxins.