Tumorigenic effects of chronic administration of benzylhydrazine dihydrochloride and phenylhydrazine hydrochloride in Swiss mice.

Separate solutions of 0.015% benzylhydrazine dihydrochloride and 0.01% phenylhydrazine hydrochloride were given continuously in the drinking water of 6- and 5-week-old randomly bred Swiss mice for the remainder of their life. The consumption of benzylhydrazine dihydrochloride significantly increased the lung tumor incidence from 21 to 42% in the females, while in phenylhydrazine hydrochloride-treated mice, the incidence of blood vessel tumors rose significanly from 5 to 22% in females and from 6 to 20% in males, as compared with the controls. Histopathologically, the tumors were classified as adenomas and adenocarcinomas of lungs and angiomas and angiosarcomas of blood vessels. The study thus proves for the first time the tumorigenicity of benzylhydrazine dihydrochloride. It also confirms the tumor inducing ability of phenylhydrazine hydrochloride, which is used in medicine for treatment of polycythemia vera.