The induction of tumors in Rana temporaria with nitrosamines.

Dimethylnitrosamine (DMNA) and diethylnitrosamine (DENA) dissolved in tank water in a dose of 5 and 50 ppm, resp. induced tumors of liver (hepatocellular cancers and adenomas), and of hematopoietic system (hemocytoblastosis). DMNA induced neoplasms in 19 of 43 frogs (44.2%); the average latent period being 18.2 weeks, while DENA induced tumors in 41 of 94 animals (43.6%) within a mean latent period 19.7 weeks. Results of this investigation show the possibility to use anuran amphibians in shorttermed experiments in the study of nitrosocompounds carcinogenicity as well as a biological indicator for environmental pollution.