Carcinogenicity of 3-chloronitrosopiperidine, 4-chloronitrosopiperidine, and 3,4-dichloronitrosopiperidine in Fischer rats.

Three chlorinated nitrosopiperidines, 3-chloro-, 4-chloro-, and 3,4-dichloronitrosopiperidine, were administered to groups of 20 male Fischer 344 rats at a concentration of 0.17 mM in drinking water. Treatment with the monochloro compounds lasted for 30 weeks, while treatment with the dichloro compound lasted for 21 weeks. Almost all of the animals died with esophageal tumors. There was also a significant incidence of tumors of the forestomach and tongue in the rats treated with the monochloro compounds. Using the rate of death of the animals with tumors as an index, the relative potency of the three compounds increases from 3-chloro- to 4-chloro- to 3,4-dichloronitrosopiperidine.