Epidemiologic evidence on the relationship between organic
solvents and
cancer is reviewed. In the 1980s, more than a million persons were potentially 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 regularly exposed. There is evidence for increased risks of
cancer following 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 habits cannot be excluded--and
non-Hodgkin's lymphoma); and
carbon tetrachloride (lymphohematopoietic
malignancies). An excess risk of liver and
biliary tract cancers was suggested in the cohort with the high exposure to
methylene chloride, but not found in the other cohorts where an excess risk of
pancreatic cancer was suggested.
1,1,1-trichloroethane has been used widely, but only a few studies have been done suggesting a risk of
multiple myeloma. A causal association between exposure to
benzene and an increased risk of
leukemia is well-established, as well as a suggested risk of lung and
nasopharynx cancer in a Chinese cohort. Increased risks of various
gastrointestinal cancers have been suggested following exposure to
toluene. Two informative studies indicated an increased risk of
lung cancer, not supported by other studies. Increased risks of lymphohematopoietic
malignancies have been reported in 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 identify the specific causative agent[s].) A large number of studies of workers exposed to
styrene have evidenced no consistent excess risk of all lymphohematopoietic
malignancies, although the most sensitive study suggested an excess risk of
leukemia among workers with a high exposure.