The effect of deuterium on the carcinogenicity of nitroso-methyl-n-butylamine.

Nitrosomethyl-n-butylamine and its derivatives, labeled with deuterium in the methyl group or at the alpha position of the butyl group, were given to rats in drinking water at equimolar doses for approximately 20 weeks. Two concentrations were used, 16 mg/l and 6.25 mg/l. The unlabeled compound was not as toxic as its analog labeled in the methyl group, which caused the early death of some of the test animals. The methyl-labeled compound was a more effective carcinogen, and the butyl-labeled compound was a less effective carcinogen, than the unlabeled compound, as measured by the rate of death of animals with tumors of the esophagus. Almost all of the surviving animals died with esophageal tumors, basal cell papillomas and carcinomas.