Hepatotoxicity of titanium dioxide nanoparticles

The food additive E171 (titanium dioxide, TiO₂), is widely used in foods, pharmaceuticals and cosmetics. It is a fine white powder, with at least one third of its particles sized in the nanoparticulate (˂100 nm range, TiO₂ NPs). The use of E171 is controversial as its relevant risk assessment has never been satisfactorily accomplished. In vitro and in vivo studies have shown dose-dependent toxicity in various organs including the liver. TiO₂ NPs have been shown to induce inflammation, cell death and structural and functional changes within the liver. The toxicity of TiO₂ NPs in experimental models varies between organs and according to their physiochemical characteristics and parameters such as dosage and route of administration. Among these factors, ingestion is the most significant exposure route, and the liver is a key target organ. The aim of this review is to highlight the reported adverse effects of orally administered TiO₂ NPs on the liver and to discuss the controversial state of its toxicity.