Mechanisms of action of N-nitroso compounds.

There is ample evidence from studies in experimental animals that N-nitroso compounds are carcinogenic because in the body they form potent electrophilic alkylating agents. These reactive intermediates are formed by spontaneous decomposition in the case of nitrosoureas and related compounds, or by metabolic activation in the case of N-nitrosamines. The electrophiles subsequently react with DNA of target tissues to form altered bases which leads to the initiation of carcinogenesis. There is now convincing evidence that the biological activity of N-nitroso compounds in humans does not differ substantially from that in experimental animals. We can therefore predict with a high degree of confidence that N-nitroso compounds including nitrosamines are carcinogenic in man.