Differential toxic effects of food contaminant mixtures in HepaRG cells after single or repeated treatments

Through diet, people are chronically exposed to low doses of a large number of contaminants that could exhibit adverse health effects. Toxicological evaluation of food contaminants increases in complexity when the exposure involves chemical mixtures. The aim of this study is to investigate the genotoxic potential, through measuring (C)H2AX induction, of six common mixtures of food contaminants to which French adult consumers are chronically exposed. Mixtures were identified by combining information from consumption surveys and contaminant concentration levels in foods. Both single and repeated exposures were evaluated in human liver-derived HepaRG cells. Our results indicated that after a single 24-h exposure, only one mixture induced genotoxicity, and that response occurred at the highest concentration tested. In contrast, we observed after repeated exposures over 3 or 7 days, induction of (C)H2AX for all mixtures except one, and a time- and concentration-dependent manner toxicity for four mixtures. Interestingly, we also observed a non-monotonic cytotoxicity concentration-response for one mixture, which might reflect cellular adaptation to the exposure. In conclusion, our study demonstrated that longer-term treatments for in vitro toxicological evaluation, instead of the classical 24 h treatment, may be more relevant regarding human toxicology assessment.