Toxic and carcinogenic effects of nitrosodimethylamine in mink.

In a feeding experiment, 96 mink divided into four groups were kept on diets in which each animal received from 0.04-0.07 mg/kg bw NDMA/day. After four months' feeding the mink were still in good health. Except for 20 mink kept for breeding, the animals were skinned. They showed no gross lesions; however, in the livers of mink receiving a total of 16-21 mg/kg bw NDMA some of the smaller hepatic veins were partially occluded. The 20 remaining mink and their offspring were all kept on the same diet, which included 10% herring meal with a NDMA content of 7.2-7.8 mg/kg. After 233 experimental days and a total intake of 26 mg/kg bw NDMA one male died of liver fibrosis and occlusive changes in the hepatic veins. The remaining 16 in the parent group and 22 in the F1 group developed haemangiomatous liver tumours after a total intake of 25-87 mg/kg bw NDMA. The carcinogenic action of NDMA on mink appears to be nearly 100% if the exposure time is long enough and if the dose is near to the hepatotoxic level.