Mutagenic activity in the stomach and small intestine of rats after oral administration of nitrosated beef extract.

The products formed by the reaction of beef extract with nitrite were assayed in the Salmonella/microsome mutagenicity test. In strain TA1538, TA98 and TA100 a direct-acting mutagenic response was observed. The presence of liver-microsome preparation resulted in decreased mutagenicity. To study the absorption, distribution and excretion of mutagenic substances in nitrosated beef extract, the test material was given perorally to rats. Investigations of the stomach, bile fluid, urine, small intestine and blood samples were carried out, and mutagenicity was found in the contents of stomach and small intestine. It is supposed that unlike beef extract itself, its nitroso product is not excreted in the bile but passes directly from the stomach and small intestine.