Carcinogenicity in rats of nitrosomethylethylamines labeled with deuterium in several positions

Nitrosomethylethylamine and four of its derivatives labeled with deuterium at various positions were administered to male Fischer 344 rats in drinking water at equimolar doses for 30 weeks. The doses were 30 and 6 mg/liter at the rate of 3 and 0.6 mg/week, approximately. The rats receiving the higher doses died earlier and had more tumors than those given the lower doses. At both dose levels, nitrosomethylethyl-1-d2-amine and nitrosomethylethyl-d5-amine were more effective carcinogens than was unsubstituted nitrosomethylethylamine. Rats died earlier and more of them had tumors after receiving the deuterium-labeled compounds. Nitrosomethyl-d3-ethylamine and nitrosomethyl-d3-ethyl-d5-amine did not greatly differ in carcinogenic effectiveness from the unsubstituted compound. Both nitrosamines having deuterium in the methyl portion of the ethyl group, nitrosomethylethul-d5-amine and nitrosomethyl-d3-ethyl-d5-amine, induced esophageal tumors as well as liver tumors in the rats.