Metabolism of 2-naphthylamine and benzidine by rat and human bladder organ cultures.

The metabolism of benzidine and 2-naphthylamine, two aromatic amines which are carcinogenic for the human, was investigated in human and rat bladder organ cultures. There was little oxidative metabolism of either carcinogen in either species. In particular, N-hydroxy-2-naphthylamine, a proximate carcinogen of 2-naphthylamine could not be detected. In contrast, large amounts of the acetylated metabolites, N-acetylbenzidine, N,N-diacetylbenzidine and N-acetyl-2-naphthylamine were formed both in rat and human bladder cultures. The results suggest that metabolism of these carcinogens in situ in the bladder is unlikely to contribute to their carcinogenic effect but instead may have a positive protective role.