The Occupational Studies Section conducts epidemiologic studies to identify and quantify occupational and other causes of cancer. During the past year a study of pesticide applicators found excesses of lung and brain cancer. In another study, brain cancer was associated with occupational exposure to methylene chloride and risks rose with increasing probability and level of exposure. Brain cancer was also elevated among Chinese women exposed to pesticides. Multiple myeloma and non-Hodgkin's lymphoma was elevated among Nebraska women living on farms who reported mixing/applying pesticides. Bladder and lung cancer were excessive among Russian workers exposed to beta-napthtylamine and benzidine. In a study from the northeastern U.S., bladder cancer was elevated among workers in the leather and textile industries. In a study of Chinese workers, benzene was found to cause genetic damage by chromosomal aberration rather than point mutation. Prostate cancer rates are known to be higher in the southeastern U.S. than in other regions. A death certificate study found that about 40% of this excess could be explained by past employment in agriculture. Proceedings from an international meeting on occupational cancer among women sponsored by the NCI was published in three volumes of the Journal of Occupational Medicine. The risk of non-Hodgkin's lymphoma was inversely associated with intake of food high in vitamins C and A, particularly among men. Tobacco was associated with the development of prostate, colon, and pancreatic cancer. Also completed were methodologic efforts designed to improve procedures for exposure assessment in case-control and cohort studies. Currently under investigation include studies of acrylonitrile,, asbestos, benzene, butadiene, diesel exhausts, formaldehyde, methylene chloride, nitrates in drinking water, organic solvents, pesticides, and silica. Occupational groups with complex exposures under study include farmers, migrant and seasonal workers, industrial workers in Turkey, lawn care workers, fire fighters, and marine inspectors.
