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J Appl Toxicol,
2012]
Polycyclic aromatic hydrocarbons (PAHs) are known to exert mutagenic and carcinogenic effects. Research on extracted organic matter (EOM) from environmental mixtures has indicated several mechanisms of intracellular damage in living organisms. The toxic effect of environmental pollutants is usually assessed on cell systems or in single species. We used the model organism Caenorhabditis elegans to compare the effect of synthetic PAHs with that of the EOM from environmental mixtures. The biological effect was measured by monitoring the expression level of some crucial genes, sensitive parameters of the organism's response. The results indicate the ability of C. elegans to counteract damage by mounting a stress-response only in the presence of EOM. On the other hand the exposure of C. elegans to a mixture of synthetic PAHs determines the silencing of the transcriptional machinery, thus preventing the synthesis of proteins that are important for both the damage repair mechanism and survival itself. The results strongly indicate that the study of environmental toxicant effects at the molecular level may provide information on their mechanism of action.
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Environ Res,
2014]
Soil quality is traditionally evaluated by chemical characterization to determine levels of pollutants. Biological tools are now employed for soil monitoring since they can take account of the global biological effects induced by all xenobiotics. A combined monitoring of soils based on chemical analyses, human-related in vitro models and ecotoxicological assay was applied in the Lomellina, a semirural area of northern Italy. Chemical characterization indicated overall good quality of the soils, with low levels of toxic and carcinogenic pollutants such as heavy metals, PAHs, PCDD/Fs and PCBs. HepG2 cells were used as a model for the human liver and BALB/c 3T3 cells to evaluate carcinogenic potential. Cells were treated with soil extractable organic matter (EOM) and the MTS assay, DNA release and morphological transformation were selected as endpoints for toxicity and carcinogenicity. Soil EOMs induced dose-dependent inhibition of cell growth at low doses and cytotoxicity only at doses of 500 and 1000 mg soil equivalents/ml. Potential issues for human health can be hypothesized after ingestion of soil samples from some sites. No statistically significant inductions of foci were recorded after exposure to EOMs, indicating that the levels of the soil-extracted organic pollutants were too low to induce carcinogenesis in our experimental conditions. An acute phytotoxicity test and studies on Caenorhabditis elegans were used as ecotoxicological assays for plants and small invertebrates. No significant alerts for ecotoxicity were found. In this proposed case study, HepG2 cells detected differences in the toxicity of soil EOMs, indicating that this cell line could be appropriate to assess the potential harm caused by the ingestion of contaminated soil. Additional information on the carcinogenic potential of mixtures was provided by the cell transformation assay, strengthening the combined approach.