Comparative carcinogenicity in the rat of 2-hydrazinothiazoles with nitrofuryl, nitrophenyl, or aminophenyl substituents in the 4-position.

2-Hydrazino-4-(5-nitro-2-furyl)thiazole , 2-(2 , 2-dimethyihy drazi no)-4-(5-nitro-2-furyl)thiazole, 2-hydrazino-4-(4-nitro phenyl)thiazole, and 2-hydrazino-4-(4-aminophenyl)thiazole were fed to female Sprague-Dawley rats, and all were found to be potent carcinogens. Each induced chiefly carcinomas of the mammary gland (32/35 , 30/3 1, 27/34, 34/35 , respec tively), as well as a lower incidence of tumors of other organs. The carcinogenic relationship of these four com pounds to formic acid 2-[4-(5-nitro-2-furyl)-2-thiazolyll hy drazide is discussed.