Toxicological assessment of two silane-modified clay minerals with potential use as food contact materials in human hepatoma cells and Salmonella typhimurium strains

Reinforced technological properties can be achieved by adding small amounts of organo-modified clay minerals into traditional polymeric matrices. The result is a final product with improved characteristics destined to several applications, among them, food packaging. However, it is mandatory to evaluate the toxicity of novel food contact materials, as well as all new substances destined to this purpose. The present work shows for the first time in a human target cell line from hepatic origin (HepG2), and in Salmonella typhimurium, a prokaryotic system, the in vitro toxicological evaluation of Clay3 and Clay4, two silane-modified montmorillonites intended to be incorporated into food containers. Cytotoxic effects were evaluated (0 to 250 μg/mL) after 24 and 48 h of exposure and only Clay4 showed toxic effects. Once the mean effective concentration was calculated, different mechanistic biomarkers were investigated for Clay4: cell death, reactive oxygen species (ROS) production, glutathione content, mutagenicity, and standard and oxidative genotoxicity. Only a significant ROS production after both times of exposure, as well as a significant oxidative DNA damage after the longer time assayed were obtained with Clay4. Between both silane-modified clay minerals studied Clay3 is the better candidate to develop new reinforced packaging materials in base to its good toxicological profile.