The potential for skin irritation, phototoxicity, and sensitization of ZnO nanoparticles

In spite of widely use of zinc oxide (ZnO) nanoparticles (NPs) in cosmetic industry and in our daily lives, insufficient studies have evaluated the potential of their toxic response. This study was conducted to investigate the potential of cytotoxicity induced by ZnO NPs, especially influences of the surface charge and different particle size. Assessment of potential of skin irritation was estimated using human skin equivalent model (HSEM), and an animal model. And the evaluation of skin phototoxicity was tested by the 3T3 neutral red uptake test. Lastly, the potential of skin sensitization was evaluated by a local lymph node assay (LLNA). The results from this study demonstrated that ZnO NPs are not dermal sensitizers and do not induce skin irritation. But they may produce phototoxicity.