Tumorigenicity of beta-phenylethylhydrazine sulfate in mice

The continuous lifetime administration of 0.015% beta-phenylethylhydrazine sulfate in the drinking water of Swiss mice, beginning at 6 weeks of age, gave rise to tumors of the lungs and blood vessels. As compared to untreated controls, the incidence of lung tumors rose from 21 to 56% in females and from 23 to 36% in males, while the incidence of vascular tumors increased from 5 to 44% in females and from 6 to 8% in males. Statistically, the increased incidence of tumors of lungs and blood vessels in females appears to be significant. The treatment had no statistically significant effect on the development of tumors in males. Histopathological examination revealed the characteristic appearance of adenoma and adenocarcinoma of the lungs, and angioma and angiosarcoma of blood vessels. This study reports for the first time the tumorigenicity of beta-phenylethylhydrazine sulfate, which is currently used to treat mental depression.