Toxicity assessment of organomodified clays used in food contact materials on human target cell lines

Nowadays, the incorporation of organomodified clays based on montmorillonite into polymers intended for packaging industry is a reality. The final result is a polymer nanocomposite with enhanced barrier properties. Different organomodified clays are already commercially available and others new ones are being developed; however little is known about their safety. In the present work, the cytotoxic effects (a tetrazolium salt reduction and protein content) of three organomodified clays, Cloisite (R) 20A, a commercial clay, and Clay 1 and Clay 2, two novel modified clays developed by the Packaging, Transport, & Logistics Research Institute, were evaluated in Caco-2 and HepG2 cells after 24 and 48 h of exposure. Our results showed that only Clay 2 induced toxic effects in both cell lines. The mean effective concentration was calculated for each case, showing Caco-2 to be more sensitive than HepG2. Moreover, in order to elucidate the toxicity mechanisms of Clay 2, different mechanistic biomarkers were investigated. Interleukin leakage and generation of intracellular reactive oxygen species were not observed, whereas glutathione content decreased in HepG2. DNA damage (comet assay) was induced in both cell lines at the highest concentration tested. Overall, results show that the type of day, the concentrations range and the type of cell line play an important role in the toxicity observed. (C) 2014 Elsevier B.V. All rights reserved.