Carcinogenicity of chlorinated nitrosotrialkylureas in rats

Four chlorinated derivatives of nitrosotrialkylureas were tested for carcinogenicity by oral administration by gavage to Sprague-Dawley rats. All of the compounds were very toxic, and all were carcinogenic, inducing tumors of the non-glandular stomach and of the lungs. The commonest tumors were carcinomas and papillomas of the non-glandular stomach and alveolar cell adenomas of the lungs. Nitrosochloroethyldimethylurea induced most tumors, but it was possible to administer higher doses of this compound than of the others, which were nitrosochloroethydiethylurea, nitrosomethylbis-(chloroethyl)-urea and nitrosotris-(chloroethyl)-urea. The last of these was a particularly toxic compound so that the maximum total dose given was only 0.07 millimole per rat.