Comparison of carcinogenicity of N-alkyl-N'-nitro-N-nitroso-guanidines.

Carcinogenicity of seven homologs of N-alkyl-N'-nitrosoguanidine (N-alkyl-NNG), namely, N-methyl-NNG, N-propyl-NNG, N-butyl-NNG, N-isobutyl-NNG, N-pentyl-NNG, and N-hexyl-NNG, was examined by injecting the compounds subcutaneously into rats. All of them except N-isobutyl-NNG and N-hexyl-NNG were carcinogenic, but N-ethyl-NNG followed by N-methyl-NNG were stronger carcinogens than those with longer alkyl chains.