The tumorigenic effect of low dose levels of N-methyl-N-formylhydrazine in mice.

Solutions of 0.002 and 0.001% N-methyl-N-formylhydrazine (MFH) were given separately daily in drinking water to 6-week-old randomly bred Swiss mice for life. The treatments resulted in induction of tumors of the lungs, blood vessels, liver and gall bladder. The 0.002% solution gave rise to tumors of the above tissues in incidences of 76, 27, 28 and 11%, respectively, while the 0.001% solution induced tumors in incidences of 75, 23, 7 and 6%. Histopathologically, the neoplasms were adenomas and adenocarcinomas of lungs, angiomas and angiosarcomas of blood vessells, benign hepatomas, liver cell carcinomas and adenomas and adenocarcinomas of the gall bladder. MFH is an ingredient of the edible mushroom, the false morel Gyromitra esculenta. The present study proves the carcinogenicity of MFH administered at low dose levels. The possible environmental significance of the findings to the human population is discussed.