Carcinogenicity of nitrosododecamethyleneimine in NZR/Gd inbred rats

Nitrosododecamethyleneimine (NDMI) was given to NZR/Gd rats by gavage in olive oil solution, confirming its hepatocarcinogenic activity. Twenty male and 20 female rats received 2.5 mg NDMI twice a week for 52 weeks; a further 10 male rats received 25.0 mg twice a week for 12 weeks. Two-thirds of the animals survived more than 2 years. Of the rats given the high dose of NDMI 50% died with hepatocellular carcinomas, as did 8% of the rats receiving the lower dose and 0.5% of untreated rats (p less than 0.001). In NDMI-treated animals the incidence of atriocaval tumours (p less than 0.001) and of lung tumours (p less than 0.025) was also significantly higher than in untreated controls.