A COMPARISON OF THE TUMORS INDUCED BY COAL-TAR AND BENZO[A]PYRENE IN A 2-YEAR BIOASSAY

The tumorigenicity of two coal tar mixtures was compared to that of be nzo[a]pyrene after 2 years of feeding, Mixture 1, a composite of coal tar from seven coal gasification plant waste sites, was fed to female B6C3F1 mice (48 mice per group) for 2 years at doses of 0.0, 0.01, 0.0 3, 0.1, 0.3, 0.6 and 1.0%, Mixture 2, which was composed of coal tar f rom two of the seven waste sites and another site having a high benzo[ a]pyrene content, was fed at doses of 0.0, 0.03, 0.1 and 0.3%, Additio nal groups of mice were fed 0, 5, 25 and 100 ppm benzo[a]pyrene, The c oal tar diets induced a dose-related increase in hepatocellular adenom as and carcinomas, alveolar/bronchiolar adenomas and carcinomas, fores tomach squamous epithelial papillomas and carcinomas, small intestine adenocarcinomas, histiocytic sarcomas, hemangiosarcomas in multiple or gans and sarcomas, Benzo[a]pyrene treatment resulted in an increased i ncidence of papillomas and/or carcinomas of the forestomach, esophagus and tongue, A comparison of the results indicated that the benzo[a]py rene in the coal tar diets could be responsible for the forestomach tu mors, In contrast, the lung and liver tumors appeared to be due to oth er genotoxic components contained within the coal tar mixture, while t he small intestine tumors resulted from chemically-induced cell prolif eration that occurred at high doses of coal tar.