Hepatocyte apoptosis and its molecular mechanisms in mice caused by titanium dioxide nanoparticles

Toxicological effects of titanium dioxide nanoparticles: a review of in vitro mammalian studies

BACKGROUND AND OBJECTIVE

Recent rapid advances in nanotechnology raise concerns about development, production route, and diffusion in industrial and consumer products of titanium dioxide nanoparticles (TiO2-NPs). In fact, compared to recent increase in applications of this nanomaterial, the health effects of human exposure have not been systematically investigated. The aim of this review was to provide a comprehensive overview on the current knowledge regarding the effects of TiO2-NPs on mammalian cells.

EVIDENCE AND INFORMATION SOURCES

This review is based on an analysis of the current literature on this topic.

STATE OF THE ART

Fine TiO2 particles have been considered as safe and to pose little risk to humans, suggesting that exposure to this material is relatively harmless. However, available data in the literature showed that TiO2-NPs can cause several adverse effects on mammalian cells such as increase of reactive oxygen species (ROS) production and cytokines levels, reduction of cell viability and proliferation, induction of apoptosis and genotoxicity.

PERSPECTIVES AND CONCLUSIONS

Additional research is needed to obtain up-to-date knowledge on health effects of TiO2-NPs and to avoid any potential risk correlated to their exposure. Consequently, future studies need to: (1) use an homogeneous and rigorous exposure classification to clarify how the physicochemical properties of TiO2-NPs correlate with their toxicological effects; (2) assess the potential adverse effects of low level exposures to TiO2-NPs, as most of the information currently available originates from studies in which exposure levels were excessively and unrealistically high; (3) identify the possible roles of TiO2-NPs in genotoxicity and carcinogenicity (4) carry out epidemiologic studies of exposed workers to provide an assessment of possible risks correlated to the occupational exposure to TiO2-NPs.

Toxicological Issues of Nanoparticles Employed in Photocatalysis

A huge amount of different nanomaterials is nowadays on the market used for various specific applications. Some nanomaterials such as TiO

Hence these materials are used for many applications, e.g., for self-cleaning and antibacterial coatings on different surfaces and for the purification of wastewater where the cleaning can be induced by simple exposure to sunlight. Because of the frequent use of these nanoparticles it is important to investigate the life cycles of these nanostructured materials as well as their environmental impact and their toxicity to animals and humans.

This review first gives a short overview about nanotechnology and nanotechnological products as well as about photocatalysis and semiconductors used in this field. We then discuss the need for a new technology named nanotoxicology and the problems occurring when investigating the toxic potential of nanomaterials as well as the life cycle of nanomaterials. Furthermore, we focus on the environmental impact of TiO