Antimutagenic and antigenotoxic effects of vegetable matrices on the activity of pesticides

A Novel Strategy to Predict Carcinogenicity of Antiparasitics Based on a Combination of DNA Lesions and Bacterial Mutagenicity Tests

Genotoxicity and carcinogenicity testing of pharmaceuticals prior to commercialization is requested by regulatory agencies. The bacterial mutagenicity test was considered having the highest accuracy of carcinogenic prediction. However, some evidences suggest that it always results in false-positive responses when the bacterial mutagenicity test is used to predict carcinogenicity. Along with major changes made to the International Committee on Harmonization guidance on genotoxicity testing [S2 (R1)], the old data (especially the cytotgenetic data) may not meet current guidelines. This review provides a compendium of retrievable results of genotoxicity and animal carcinogenicity of 136 antiparasitics. Neither genotoxicity nor carcinogenicity data is available for 84 (61.8%), while 52 (38.2%) have been evaluated in at least one genotoxicity or carcinogenicity study, and only 20 (14.7%) in both genotoxicity and carcinogenicity studies. Among 33 antiparasitics with at least one old result in in vitro genotoxicity, 15 (45.5%) are in agreement with the current ICH S2 (R1) guidance for data acceptance. Compared with other genotoxicity assays, the DNA lesions can significantly increase the accuracy of prediction of carcinogenicity. Together, a combination of DNA lesion and bacterial tests is a more accurate way to predict carcinogenicity.

Genotoxicity of pesticide mixtures present in the diet of the French population

Consumers may be simultaneously exposed to several pesticide residues in their diet. A previous study identified the seven most common pesticide mixtures to which the French population was exposed through food consumption in 2006. The aim of this study was to investigate if the seven mixtures are potentially cytotoxic and genotoxic and if so, whether compounds in a same mixture have a combined effect. The cytotoxicity and genotoxicity of the seven mixtures were investigated with a new assay (γ-H2AX) using four human cell lines (ACHN, SH-SY5Y, LS-174T, and HepG2). Mixtures were tested at equimolar concentrations and also at concentrations reflecting their actual proportion in the diet. Irrespective of the cell line tested, parallel cytotoxicity of the seven mixtures was observed. Only one mixture was genotoxic for the HepG2 cells at concentrations = 3 μM in equimolar proportion and at 30 μM in actual proportion. Caspase 3/7 activity, the comet assay, and reactive oxygen species production were also investigated using the same mixture and HepG2 cells. Our results suggest that pesticide metabolites from the mixture generated by HepG2 cells were responsible for the observed damage to DNA. Among the five compounds in the genotoxic mixture, only fludioxonil and cyprodinil were genotoxic for HepG2 cells alone at concentrations = 4 and 20 μM, respectively. Our data suggest a combined genotoxic effect of the mixture at low concentrations with a significantly higher effect of the mixture of pesticides than would be expected from the response to the individual compounds. Environ. Mol. Mutagen. 2012. © 2012 Wiley Periodicals, Inc.

Biomonitoring of rural workers exposed to a complex mixture of pesticides in the municipalities of Tianguá and Ubajara (Ceará state, Brazil): genotoxic and cytogenetic studies

In recent years, the use of pesticides in agriculture has been steadily increasing, and associations between exposure to agricultural chemicals and DNA damage and cancer have been reported. Brazil is one of the world leaders in pesticide use; however, studies that evaluate the impact of pesticide exposure on cancer incidence and mortality are very scarce in the Brazilian population. The alkaline comet assay and the chromosome aberration (CA) test were used to evaluate primary DNA damage in the peripheral blood lymphocytes of workers exposed to a complex mixture of pesticides in two small rural communities in the municipalities of Tianguá and Ubajara, located in the western part of Ceará State (Northeast Brazil), which are among the largest agricultural areas of the state. The comet assay showed that the damage index and damage frequency observed in the exposed groups were significantly higher in relation to the controls (P < 0.05). On the other hand, no differences were detected regarding structural and numerical CAs in the communities evaluated. Additionally, the observed levels of DNA strand breaks and frequencies of CAs, stratified for exposure time, were not statistically different for individuals of either rural community. Our results suggest that the damages caused by pesticides in our study area were not great enough to induce permanent mutations or to interfere with mitotic apparatus formation; minimal pesticide damages could have undergone cellular repair, explaining the absence of structural and numerical CAs.

Testing of the mutagenicity and genotoxicity of metolcarb by using both Ames/Salmonella and Allium test

Mutagenic and genotoxic effects of metolcarb were investigated by both bacterial reverse mutation assay in Salmonella typhimurium TA97, TA98, TA100 and TA102 strains with or without metabolic activation system (S9) and Allium cepa root meristematic cells, respectively. Metolcarb was dissolved in DMSO in Ames/Salmonella test system. 0.1, 1 and 10 microg/plate doses of metolcarb were found to be mutagenic S. typhimurium TA98 without S9. In Allium root growth inhibition test, EC50 value was determined 200 ppm and 0.5xEC50, EC50 and 2xEC50 concentrations of metolcarb were introduced to onion tuber roots and distilled water used as a negative control. Mitotic index (MI), increased in all concentrations compared to control at each exposure time. While disturbed anaphase-telophase, chromosome laggards, stickiness and bridges were observed in anaphase-telophase cells, pro-metaphase, C-mitosis, polyploidy, binuclear cells and disturbed nucleus were observed in other cells. The results were also analyzed statistically by using SPSS for Windows, Mann-Whitney test and Duncan's multiple range tests were performed respectively.