Nitrite-induced volatile mutagens from normal human feces.

Volatile mutagens (putative carcinogens) were produced from normal human and animal feces upon incubation with sodium nitrite in saline at 37 C for 48 hours. The mutagens were detected by using Ames' Salmonella typhimurium tester strain TA1535 without microsomes, on plates inverted over samples in sealed containers. Mutagenicity was maximal at 0.2 to 0.6 M NaNO2 and at pH 6.2 to 6.8. Reversions per plate varied from approximately 30 to 450 (1.5 to 25 x background) within the normal human population. Sodium ascorbate and alpha-Tocopherol (at one-half [NaNO2]) each reduced the mutagenicity by approximately 30%. Two standard N-nitroso-compounds were mutagenic in the system. We propose that the mutagenicity in our system is probably caused by the formation of volatile N-nitroso-compounds and that addition of nitrite to human feces in vitro enhances a process that occurs in vivo.