Multiple endpoints to evaluate pristine and remediated titanium dioxide nanoparticles genotoxicity in lung epithelial A549 cells

Titanium dioxide nanoparticles (TiO2 NP) are broadly used in a wide range of applications. Several studies have reported that TiO2 NP possess cytotoxic and genotoxic properties that could induce adverse health effects in humans. The FP7 Sanowork project was aimed to minimize occupational hazard and exposure to engineered nanomaterials (ENM), including TiO2 NP, through the surface modification in order to avoid possible adverse toxic effects for humans. In this study we investigated cytotoxicity, genotoxicity and epigenetic properties of TiO2 NP uncoated and coated with silica or citrate, as well as of the benchmark material P25. We used a panel of in vitro assays in the human lung epithelial cell line A549, in order to better understand if the remediation strategy adopted was able to counteract possible toxic effects of uncoated TiO2 NP. Our results showed that the uncoated TiO2 NP were both cytotoxic and genotoxic, and the remediation strategy adopted did not reduce the adverse effects of uncoated TiO2 NP. In particular, the presence of citrate was able to increase their cytotoxicity and genotoxicity, exerting also epigenotoxic effects, as evaluated by the marked reduction of LINE-1 methylation levels.