Carcinogenic effect of nitrosopyrrolidine, nitrosopiperidine and nitrosohexamethyleneimine in Fischer rats.

Three homologous cyclic nitrosamines, nitrosopyrrolidine, nitrosopiperidine and nitrosohexamethyleneimine, were administered to groups of 20 female F344 rats in drinking water, as 0.9 mM solutions. Treatment with the latter 2 compounds lasted 28 weeks, at which time several animals had died with esophageal tumors. All of the animals in these 2 groups were dead by the 36th week of the experiment. Most of the animals given nitrosohexamethyleneimine also had angiosarcomas of the liver, and a few hepatocellular carcinomas were seen. Treatment with nitrosopyrrolidine lasted 50 weeks and the first animal in the group died at the 63rd week with an hepatocellular carcinoma. By the 110th week, almost all of these animals had died with the same type of tumor, and the 2 survivors were then killed. Many of the hepatocellular carcinomas had metastasized. There were no tumors of the liver in the rats treated with nitrosopiperidine.