Carcinogenicity of 5-nitrofurans and related compounds with amino-heterocyclic substituents.

Carcinogenicity of eight 5-nitrofurans with heterocyclic substituents at the 2-position of the furan ring was investigated by feeding the chemicals to Sprague-Dawley female rats. N-[5-(5-nitro-2-furyl)-1,3,4-thiadiazol-2-yl]acetamide induced in 30 rats the highest incidence of tumors with the greatest number of tissues involved: forestomach squamous cell tumors (22), kidney pelvis transitional cell carcinomas (15), pulmonary alveolar cell carcinomas (16), hemangioendothelialsarcomas (20) of the intestine, mesentery, liver, lung, and pancreas, and a few tumors of other tissues. 2-Amino-5-(5-nitro-2-furyl)-1,3,4-thiadiazole, 2-amino-5-(5-nitro-2furyl)-1,3,4-oxadiazole, and trans-2-[dimethylamino)methylimino]-5-[2-(5-nitro-2-furyl)vinyl]-1,3,4-oxadiazole produced high incidences of mammary tumors. The other four 5-nitrofurans tested: N-[4-(5-NITRO-2-FURYL)-2-THIAZOLYL]ACETAMIDE;2,3,4-TRIFLUORO-N-[4-(5-NITRO-2-furyl)-2-thiazoly]acetamide;5-(5-nitro-2-furyl)-1,3,4-oxadiazol-2-ol; and N-( [3-(5-nitro-2-furyl)-1,2,4-oxadiazol-5-yl]methyl)acetamide were associated with tumor incidences of 40-60%. Two other chemicals were also tested: 2-Amino-5-nitrothiazole caused a low incidence of breast and kidney pelvis tumors, and 2-amino-4-(p-nitrophenyl)thiazole induced a high incidence of breast and salivary gland adenocarcinomas and lymphomas.