Cytotoxicity and oxidative DNA damage by nanoparticles in human intestinal Caco-2 cells

The use of engineered nanoparticles in the food sector is anticipated to increase dramatically, whereas their potential hazards for the gastrointestinal tract are still largely unknown. We investigated the cytotoxic and DNA-damaging effects of several types of nanoparticles and fine particles relevant as food additives (TiO2 and SiO2) or for food packaging (ZnO and MgO) as well as carbon black on human intestinal Caco-2 cells. All particles, except for MgO, were cytotoxic (LDH and WST-1 assay). ZnO, and to lesser extent SiO2, induced significant DNA damage (Fpg-comet), while SiO2 and carbon black were the most potent in causing glutathione depletion. DNA damage by TiO2 was found to depend on sample processing conditions. Interestingly, application of different TiO2 and ZnO particles revealed no relation between particle surface area and DNA damage. Our results indicate a potential hazard of several food-related nanoparticles which necessitate investigations on the actual exposure in humans.