Authors
Sangeeta Sharna-Wagner, et al., Journal of Occupational and Environmental Medicine 2000; 42(5):517-525.

Occupation and prostate cancer risk in Sweden

This is a hypothesis-generating study reporting prostate cancer risk for various occupational and industrial categories in Sweden. Prior to this study, excess prostate cancer risks had been reported among various occupations. To provide new leads regarding occupational prostate cancer risk, the authors utilized the Swedish Cancer-Environment Registry, which links information on current employment at the time of the 1960 National Census with cancer incidence data from the National Swedish Cancer Registry for the period 1961 to 1979. A total of 36,269 men employed in 1960 developed microscopically confirmed prostate cancer and were used in this analysis. Consistent with previous studies, excess risks of prostate cancer were found among the agriculture, tobacco, sales, clerical, and mechanical industries. New findings include the excess risks observed in the industries of pig iron and steel foundries, soap and perfume manufacture, butchers and meat processors, lime and chalk production, pulp grinding and cellulose manufacture, leather tanning, veterinary medicine, forest management workers, and breeders of fur-bearing animals. In addition, small decreased risks of prostate cancer were observed in several occupations and industries that had been reported previously to have increased risks of prostate cancer, including coal miners, rubber workers, mining and quarry workers, and construction metal workers.

A variety of potential carcinogens, including polycyclic aromatic hydrocarbons, metal dust, and cutting fluids may be related to the excess risk found among pig iron workers. Exposures to carcinogenic reagents, solvents, and other chemicals, including aromatic and halogenated hydrocarbons, asbestos, diethyl-sulfate, benzyl-chloride, cadmium, trichloroethylene, and perchloroethylene may be associated with the elevated risk observed in soap and perfume workers. Butchers and meat processors had a 13% excess risk of prostate cancer. Exposure to animal steroid hormones and possibly an increased dietary consumption of meat and animal fat have been proposed to explain the risk in this group. Suspected carcinogens and bleaching agents may be related to the excess risk observed for pulp grinders and cellulose workers. Possible carcinogenic exposures among lime and chalk workers include asbestos fiber dust, bitumen fumes, and wollastonite. Noteworthy are the excess risks seen for leather workers, veterinarians, forest management workers, and breeders of fur-bearing animals since these classes of workers may have some exposures in common with farmers, including chemicals, herbicides, insecticides, hormones, and zoonotic viruses. Farmers and other agricultural workers have elevated prostate cancer risks that may be related to exposure of multiple suspected carcinogens, including pesticides, herbicides, insecticides, fertilizers, solvents, fuels and oils, dust, zoonotic viruses, microbes, fungi, and animal hormones.

Information regarding socioeconomic status, smoking, diet, physical activity, and other lifestyle factors were not provided by the Swedish Cancer-Environment Registry. In addition, specific measurements of contaminant exposure were not performed in this study; possible exposures are inferred from occupation and industry. Furthermore, information on the duration of employment was not available. However, occupational change is uncommon in Sweden and thus the occupational category reported in the 1960 national census is likely to represent an individual's usual adult job classification.

This study suggests that occupation is unlikely to play a major role in prostate cancer etiology because the observed excess risks were usually quite small (<10%). Nonetheless, future studies are needed to identify specific exposures related to the observed excess risk among farmers and other occupations and industries.