ORGANIC-SOLVENTS AND CANCER

Epidemiologic evidence on the relationship between organic solvents an d cancer is reviewed. In the 1980s, more than a million persons were p otentially exposed to some specific solvents in the United States; in Canada, 40 percent of male cancer patients in Montreal had experienced exposure to solvents; in the Finnish population, one percent was regu larly exposed. There is evidence for increased risks of cancer followi ng exposure to: trichloroethylene (for the liver and biliary tract and for non-Hodgkin's lymphomas); tetrachloroethylene (for the esophagus and cervix - although confounding by smoking, alcohol, and sexual habi ts cannot be excluded - and non-Hodgkin's lymphoma); and carbon tetrac hloride (lymphohematopoietic malignancies). An excess risk of liver an d biliary tract cancers was suggested in the cohort with the high expo sure to methylene chloride, but not found in the other cohorts where a n excess risk of pancreatic cancer was suggested. 1,1,1-trichloroethan e has been used widely, but only a few studies have been done suggesti ng a risk of multiple myeloma. A causal association between exposure t o benzene and an increased risk of leukemia is well-established, as we ll as a suggested risk of lung and nasopharynx cancer in a Chinese coh ort. Increased risks of various gastrointestinal cancers have been sug gested following exposure to toluene. Two informative studies indicate d an increased risk of lung cancer, not supported by other studies, In creased risks of lymphohematopoietic malignancies have been reported i n some studies of persons exposed to toluene or xylene, but not in the two most informative studies on toluene, Occupation as a painter has consistently been associated with a 40 percent increased risk of lung cancer. (With the mixed exposures, however, it is not possible to iden tify the specific causative agent[s].) A large number of studies of wo rkers exposed to styrene have evidenced no consistent excess risk of a ll lymphohematopoietic malignancies, although the most sensitive study suggested an excess risk of leukemia among workers with a high exposu re.