Tumor induction by N-nitroso compounds in bivalve mollusks Unio pictorum

Diethylnitrosamine (DENA) and dimethylnitrosamine (DMNA) dissolved in tank water induced neoplasms in bivalve mollusks Unio pictorum. DENA induced tumors in 18% of the animals exposed to 200 ppm and 68% of those exposed to 400 ppm; average latent periods were 71 and 61 days, respectively. DMNA induced tumors in 8% of the animals exposed to 200 ppm for 51 days and 27% of those exposed for 152 days with average latent periods of 85 and 81 days, respectively. Neoplasms were observed in the digestive gland (basophilic cell tumors; 38 cases), the hemopoietic system (hemocytoblastosis; 12 cases) and the kidney (poorly differentiated carcinoma; 1 case). It is expedient to use mollusks, both for testing of N-nitroso compounds and as a biologic indicator of hydrospheric pollution.