Tumorigenicity of minute dose levels of N-methyl-N-formylhydrazine of Gyromitra esculenta.

Separate administrations of 0.0005 to 0.00025% N-methyl-N-formylhydrazine in drinking water to 6-week-old randomly bred Swiss mice for the remainder of their lifetime induced lung neoplasms. At the high dose level, 64% of the females and 48% of the males developed lung tumors, while the corresponding tumor incidences at the lower dose level were 62% in the females and 54% in the males. In untreated controls, the lung tumor incidences were 29% in the females and 19% in the males. Histopathologically, the lesions were classified as adenomas and adenocarcinomas of the lungs. N-methyl-N-formylhydrazine is a stable constituent of the edible false morel mushroom Gyromitra esculenta. The environmental significance is discussed, in view of the carcinogenicity of minute doses of this chemical.