Mutagenicity of cyclic nitrosamines in Salmonella typhimurium: effect of ring size.

Mutagenicity of cyclic nitrosamines with varying carcinogenic potentials was assayed in the Salmonella histidine-reversion system. Mutagenicity in the pour-plate assay was compared with that in the liquid pre-incubation test. The smaller ring compounds (nitrosoazetidine, nitrosopyrrolidine, and nitrosopiperidine) exhibited a similar effect in both assays. The large ring compounds (nitrosohexamethyleneimine, nitrosoheptamethyleneimine, nitrosooctamethyleneimine, and nitrosododecamethyleneimine) were more effective in the liquid pre-incubation test. Our results suggest a reasonable relationship between their mutagenic and carcinogenic activities.