The lethal and hepatocarcinogenic effects of dimethylnitrosamine injection in the newt Triturus helveticus.

Single intraperitoneal injections of dimethylnitrosamine (DMN) in concentrations of up to 16 mg/g body weight, failed to have any lethal effect in newts. This treatment also failed to induce tumours in newts maintained for one year after injection.Six or 7 injections of 16 mg/g body weight of DMN, administered over a period of 3-4 weeks, gave rise to a short-term lethal effect due to liver necrosis and in the long term to liver tumours. The tumours induced were of similar type to nitrosamineinduced tumours in rats, one being an anaplastic liver tumour and the other nodular hepatic cell tumours.Attempts to maintain the tumours by grafting failed, probably due to homograft rejection.