N-ethyl-N-formylhydrazine tumorigenesis in mice.

N-ethyl-N-formylhydrazine (EFH) was administered as a 0.02% solution in drinking water continuously for life to randomly bred Swiss mice, from 6 weeks of age. The treatment induced tumors of the lungs, blood vessels, liver, gall bladder and preputial glands. The tumor incidences in treated females for these five tissues were 98, 94, 0, 2 and 0%, whereas in the treated males they were 78, 64, 26, 8 and 10%, respectively. Histopathologically the lesions were adenomas and adenocarcinomas of the lungs, angiomas and angiosarcomas of blood vessels, benign hepatomas, liver cell carcinomas, adenomas and adenocarcinomas of the gall bladder, and squamous cell papillomas and carcinomas of preputial glands. The study is part of a structure activity relationship inquiry and proves the carcinogenicity of EFH, a structural homologue of N-methyl-N-formylhydrazine, an ingredient of the edible false morel mushroom.