Safety evaluation of the nanoparticles of titanium dioxide and zinc oxide in antissolar formulations

Abstract

The aim of this study was to investigate the safety of sunscreen formulations containing inorganic filter, such as: zinc oxide (ZnO) and titanium oxide (TiO2), in the forms of nanoparticles (NPs), and identify aspects of their toxicity. The methodology used was based on a literature review conducted by analysis of scientific articles, selected on different electronic data bases, published in the last ten years. The results suggest that the NPs of ZnO and TiO2, when topically applied, may be considered exempt from risk, since it does not have a skin penetration potential, not being able to reach the systemic circulation, remaining in the stratum corneum (SC). Furthermore, there is a possibility of NPs achieves deeper layers of the epidermis. The feasibility and cellular function studies showed that the TiO2 NPs have a cytotoxic potential in the lung, kidney and liver cells, and this effect was dependent on the exposure time, size, chemical characteristics, surface coating and the crystallinity of NPs. Thus, it also becomes necessary to conduct further studies on the interaction of the NPs with the cells and structural molecules in those regions of the epidermis.