Distribution of radioactivity following oral administration of carcinogenic 14CH3-labelled nitrosocarbaryl in the rat.

After a single intragastric administration of 14C-labelled carcinogenic nitrosocarbaryl, a nitrosated pesticide, the distribution of radioactivity was investigated in the blood and a number of organs in male rats. The animals received 0.25 mg/kg of labelled nitrosamine and were killed following administration at timed intervals between 0.5 h and 24 h. Our results show that the greatest amount of the 14CH3--group was associated with the forestomach, tumor-susceptible tissue; the level of radioactivity is noteworthy but less important in the glandular stomach. There are also sites of radioactivity accumulation mainly in the liver. Moreover, [14C]nitrosocarbaryl was revealed in the blood suggesting that nitrosamine itself rapidly (0.5 h) crosses the intestinal barrier and in a significant quantity (13%). These facts constitute a potential carcinogenic risk.