[Mutagenic activity in the feces of normal people on a mixed diet].

Single fecal samples of 25 people, living on a normal mixed Western diet and matched for freedom from any gastrointestinal disorder, were freeze-dried and volatile compounds were collected at -60 degrees C. The residues were extracted with n-hexane-dichloromethane 1:1, and subsequently with acetone-ethylacetate 2:1. The three fractions were assayed for mutagenic activity using the Salmonella typhimurium mammalian microsomal system. Fecal mutagenic activity was observed with the tester strain TA 98 in 28% of the assayed people without microsomal activation, and in 4% of the people with strains TA 98 and TA 100 with microsomal activation.