Advances in genotoxicity of titanium dioxide nanoparticles in vivo and in vitro.

Titanium dioxide nanoparticles (TiO NPs) are currently one of the most widely used nanomaterials. Due to an increasing scope of applications, the exposure of humans to TiO NP is inevitable, such as entering the body through the mouth with food additives or drugs, invading the damaged skin with cosmetics, and entering the body through the respiratory tract during the process of production and handling. Compared with TiO coarse particles, TiO NPs have stronger conductivity, reaction activity, photocatalysis, and permeability, which may lead to greater toxicity to organisms. Given that TiO was classified as a category 2B carcinogen (possibly carcinogenic to humans), the genotoxicity of TiO NPs has become the focus of attention. There have been a series of previous studies investigating the potential genotoxicity of TiO NPs, but the existing research results are still controversial and difficult to conclude. More than half of studies have shown that TiO NPs can cause genotoxicity, suggesting that TiO NPs are likely to be genotoxic to humans. And the genotoxicity of TiO NPs is closely related to the exposure concentration, mode and time, and experimental cells/animals as well as its physicochemical properties (crystal type, size, and shape). This review summarized the latest research progress of related genotoxic effects through in vivo studies and in vitro cell tests, hoping to provide ideas for the evaluation of TiO NPs genotoxicity.