Occupational magnetic field exposure and site-specific cancer incidence: a Swedish cohort study

Objective: Based on 1,596,959 men and 806,278 women, site-specific cancer incidence during 1971 through 1984 was analyzed in relation to occupational magnetic field exposure. The objective was to explore potential associations for cancer diseases beyond those extensively studied before (leukemia and brain tumors). Methods: Exposure was assessed from Census information on occupations that were linked to a job exposure matrix based on measurements. In a basic analysis, three levels of exposure were used. In addition, subjects with a more definite low exposure were compared with an aggregate of occupations with more definite exposures. Results: Observed associations were weak and there were no evident exposure-response relationships. For all cancer, an approximate 10% increase in risk was seen in the medium and high exposure groups. Several types of cancer were associated with exposure among men, including cancer of the colon, biliary passages and liver, larynx and lung, testis, kidney, urinary organs, malignant melanoma, non-melanoma skin cancer, astrocytoma III-IV. For women, associations were seen for cancer of the lung, breast, corpus uteri, malignant melanoma and chronic lymphocytic leukemia. Conclusions: In the analysis of occupations with a more definite exposure, the most notable finding for men was an increased risk of testicular cancer in young workers, and for women a clear association emerged for cancer of the corpus uteri. The outcome suggests an interaction with the endocrine/immune system.