Comparison of the carcinogenic effects of five nitrosamines in guinea pigs.

Five nitrosamines which were potent carcinogens in rats or hamsters were administered by gavage in olive oil solution twice a week to 20 male strain 2 guinea pigs. Nitroso-2,6-dimethylmorpholine given at 80 mg/kg/week for 12 weeks or at 32 mg/kg/week for 35 weeks gave rise to hemangioendothelial sarcomas of the liver in 6 and 19 animals, respectively. The same tumors were induced in 18 animals by dinitroso-2,6,dimethylpiperazine, together with hepatocellular carcinomas in six animals. Nitrosomethyldodecylamine also induced mainly hemangioendothelial sarcomas of the liver (12 animals). A few bile duct carcinomas were also observed. Neither nitrosoheptamethyleneimine nor nitrosomethyldiethylurea seemed to induce tumors in guinea pigs under our conditions.