The effects of disulfiram (97778) or ethanol (64175) on 1,2- dichloroethane (107062) carcinogenicity were studied in rats. Sprague-Dawley-rats were exposed to 50 parts per million (ppm) 1,2- dichloroethane by inhalation plus 0.05 percent disulfiram in the diet plus 5 percent ethanol in drinking water; 50ppm 1,2- dichloroethane plus 0.05 percent disulfiram; or 50ppm 1,2- dichloroethane plus 5 percent ethanol for 24 months. Body weights were monitored. Mortality was recorded. Any dead and all surviving animals at the end of the study were necropsied. Average body weights of animals exposed to treatment protocols that included disulfiram were significantly lower than the corresponding controls. Body weights of other animals were not affected. There was no difference in survival of rats in the different treatment groups when compared with controls. 1,2-Dichloroethane plus disulfiram caused an increased incidence in intrahepatic duct cholangiomas in males and females, 18 and 34 percent, respectively, versus 0 percent in controls. The incidences of hepatocellular adenomas and interstitial cellular tumors in the testes were increased in males, 12 percent versus 0 percent in controls and 22 percent versus 4 percent in controls, respectively. Mammary adenocarcinomas in females were increased, 25 percent versus 8 percent in controls. Male rats treated with 1,2-dichloroethane plus ethanol showed a slight increase in hepatocellular adenomas, 8 percent versus 0 percent in controls. The authors conclude that rats exposed to 1,2- dichloroethane at 50ppm, the current standard, and given disulfiram in the diet have an increased carcinogenicity. As a previous study showed a similar interaction between 1,2-dichloroethane and disulfiram, such interactions may occur with other similar compounds.
Division of Biomedical and Behavioral Science, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio, 27 pages, 6 references