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The present study was designed to evaluate genotoxic markers of mancozeb exposure and withdrawal in colon and liver tissues together with histological changes in the gastrointestinal tract of Sprague Dawley rats. Thirty rats were divided into three equal groups; group I: treatment, 250 mg/kg mancozeb dissolved in corn oil administered twice weekly for 7 weeks; group II: withdrawal, the same treatment as group I after which animals were untreated for 5 weeks; group III: control, administered corn oil on the same schedule as group I for 7 weeks. All administrations were by oral gavage. Serum samples were analyzed for biochemical parameters. The comet assay and histopathological examinations were done on liver and colon specimens. The results demonstrated that mancozeb exposure caused significant increases in triglycerides and total cholesterol accompanied by decreases in glucose levels, with extensive DNA damage in liver and colon together with pathological changes in stomach, colon, and liver. Mancozeb withdrawal for 5 weeks improved the lipid and glucose profiles and decreased the degree of DNA damage and changes in the architecture of the stomach, colon, and liver. We concluded that discontinuing exposure to mancozeb fungicide for 5 weeks could ameliorate the adverse effects induced by 7 weeks of exposure to mancozeb. A longer withdrawal time may further reduce the observed genotoxicity.

8-Hydroxy-2'-deoxyguanosine (8-OHdG) is the most common biomarker of oxidative DNA damage, it is formed by chemical carcinogens and can be measured in any species. Perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) are suspected genotoxic carcinogens through induction of reactive oxygen species that are responsible for oxidative DNA damage. This study was conducted to investigate the in vitro genotoxicity of PFOA and PFNA in human lymphoblastoid (TK6) cell line. TK6 cells were exposed to PFOA at 0, 125, 250, and 500 ppm and PFNA at 125 and 250 ppm for 2 h. Single cell gel electrophoresis (comet assay) was used to measure DNA damage; at least 50 cells per sample were analyzed using comet Assay Software Project (CASP). 8-OHdG was measured in DNA of exposed cells using high-performance liquid chromatography (HPLC)-mass spectrometry (MS)/MS. Results showed that both PFOA and PFNA induced DNA damage indicated by increased tail length (DNA migration). The level of 8-OHdG was increased in a dose-dependent manner in both PFOA and PFNA exposure. We concluded that PFOA and PFNA induced DNA damage and the biomarker of oxidative DNA damage (8-OHdG) could be measured by HPLC-MS/MS. In addition, PFNA produced high level of 8-OHdG at concentrations lower than PFOA, this may indicate that PFNA is more potent genotoxicant for TK6 cells than PFOA.

This study investigated the induction of oxidative stress in the testes of adult rats exposed to chlorpyrifos (CPF). CPF was administered orally, in a dose of 30 mg/kg body weight to male rats for 90 days, twice weekly. Coadministration of water-soluble nonenzymatic antioxidant glutathione (GSH) was performed in a dose of 100 mg/kg body weight, orally, for the same period. Another two groups of male rats were administered GSH and corn oil, respectively. The activities of superoxide dismutase and GSH reductase were decreased while the levels of lipid peroxidation were increased in the testicular tissues of the exposed animals. Testosterone level in the serum was significantly decreased. A decrease in the histochemical determination of testicular alkaline phosphatase was observed in CPF-treated rats. A significant decrease in all stages of spermatogenesis in the seminiferous tubules was recorded in the exposed animals. Coadministration of GSH restored these parameters.

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