GENETIC TOXICITY OF A MIXTURE OF 15 PESTICIDES COMMONLY FOUND IN THE ITALIAN DIET

To determine the toxicological effects of complex mixtures of pesticid es, we obtained data on 100 pesticide residues in common foods of cent ral Italy, Fifteen pesticides were more regularly detected at higher l evels (dithiocarbamates, benomyl/carbendazim, thiabendazole, diphenyla mine, chlorthalonil, procymidone, fenarimol, chlorpropham, vinchlozoli n, methidathion, chlorpyriphos-ethyl, parathion-methyl, parathion, chl orfenviphos, pirimiphos-ethyl). Using itemized data on daily food cons umption in Italy, we calculated that the average exposure for an adult subject was 716 mu g/day, ranging from 148 mu g of dithiocarbamates t o 1 mu g of pirimiphos-ethyl. We made a mixture of these 15 pesticides at concentrations proportional to the ratio determined in foods and t ested it with the Salmonella-microsome assay, with and without metabol ic activation with PCB-induced rat liver S9. No mutagenic activity was observed at concentrations up to 500 mu g/plate. We also tested the s ame mixture at concentrations ranging from 0.1 to 20 mu g/ml on human lymphocytes in vitro and observed a slight but statistically significa nt increase in sister-chromatid exchanges at 1 mu g/ml. We also admini stered the mixture in corn oil by gavage to Wistar rats at doses of 1, 10, and 100 mu g/kg, After 24 hr the ratio between bone marrow polych romatic and normochromatic lymphocytes (a sign of cellular toxicity) w as decreased by the exposure, but we did not observe a significant inc rease in the frequency of micronuclei. We conclude that the pesticide mixture did not have appreciable genotoxic activity in the assays used .