Host mediated assay mutagenicity test of irradiated standard food pellets and their extracts using Salmonella typhimurium G46 and TA1530

The mutagenicity of standard food pellets from 3 suppliers were examined after gamma irradiation or steam sterilisation by means of the ''Host Mediated Assay''. Salmonella typhimurium G46 was proved to be not enough sensitive for these investigations. Using the DNA-repair deficient strain TA 1530 His-, a highly significant increase in the relative backmutation frequency was observed after feeding the experimental animals with the pellets irradiated with 3 Mrad. This increase differed within the three products between 10 and 60 fold as compared to the controls. The most radiation sensitive product caused after a dose of 0.75 Mrad a slight but significant increase of backmutation rate. Each variation was assayed using 25-100 mice (Swiss Albino). Steam sterilisation caused no significant increase in the backmutation frequency of Salmonella typhimurium TA 1530 in this system. In order to characterise the mutagenic agents, extracts from irradiated as well as unirradiated food pellets with ethanol, water or diethylether were tested in the Host Mediated Assay. It could be shown that the alcoholic extract induced the highest backmutation frequency, the water extract only a lower one and the diethylether extract a non significant increase. (author)