Mutagenicity of Daily Foodstuffs and the Effect of Nitrite Treatment

Abstract

Foodstuffs purchased from supermarkets in Wakayama prefecture were classified into 13 groups (Groups I-XIII) according to market basket method. The homogenates of 12 groups excluding Group IV; fats, oils were dried and extracted with methanol using a Soxhlet apparatus. Group IV was extracted with methanol by liquid-liquid extraction. These methanol extracts were subjected to mutagenicity assay against S. typhimurium TA 98 and TA 100 with or without S9 mix by the preincubation method.It was found that Group X (fish, molluscs, crustaceans) and XI (meat, egg) induced large numbers of His+ revertant colonies with and without S9 mix in S. typhimurium TA 100, and these two groups constituted about 80-90 percent of the total possible intake of net revertant colonies/day.Studies were also carried out to test the changes of the numbers of revertant colonies caused by nitrite treatment of each group. Groups XI, IX (seasoning, beverages), VII (green vegetables), VIII (root vegetables, seaweed), II (cereal, potato) and V (beans) showed particularly high increases of His+ revertant colonies after nitrite treatment in the absence of S9 mix. The increase of mutagenic activities was generally small in the presence of S9 mix. Total daily intake of “net His+ revertant colonies” with or without S9 mix from nitrite treated foodstuffs was calculated to be 2.5 and 1.7 times those from nitrite-untreated foodstuffs, respectively.