title: Pre-irradiation of anatase TiO2 particles with UV enhances their cytotoxic and genotoxic potential in human hepatoma HepG2 cells.
abstract: Titanium dioxide (TiO(2)) is active in the UV region of the light spectra and is used as a photocatalyst in numerous applications. Photo-activated anatase TiO(2) particles promote increased production of free radicals. This is a desirable property, although the potential toxicity of such photo-activated TiO(2) particles on exposure of humans and the environment remains unknown. Therefore, we studied whether pre-irradiation of TiO(2) particles with UV influences their cytotoxic and genotoxic potential. The TiO(2) particles, as TiO(2)-A (<25 nm) and TiO(2)-B (>100 nm), were UV pre-irradiated (24h) and tested for cytotoxic and genotoxic activities in human hepatoma HepG2 cells. Non-irradiated TiO(2)-A/B at 1.0-250 μg/ml did not reduce viability of HepG2 cells, nor induce significant increases in DNA strand breaks; only TiO(2)-A induced significant increases in oxidative DNA damage. After UV pre-irradiation, both TiO(2)-A and TiO(2)-B reduced cell viability and induced significant increases in DNA strand breaks and oxidative DNA damage. This is the first study that shows that UV pre-irradiation of anatase TiO(2) particles results in increased cytotoxic and genotoxic potential. This warrants further studies as it has important implications for environmental and human health risk assessment and preventive actions to limit human exposure.
authors.affiliation: Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, SI-1000 Ljubljana, Slovenia.
authors.forename: Jana
authors.initials: J
authors.lastname: Petković
authors.forename: Tadeja
authors.initials: T
authors.lastname: Küzma
authors.forename: Katja
authors.initials: K
authors.lastname: Rade
authors.forename: Saša
authors.initials: S
authors.lastname: Novak
authors.forename: Metka
authors.initials: M
authors.lastname: Filipič
mesh_terms: D018929:Cell Culture Techniques; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D020552:Comet Assay; D004249:DNA Damage; D056945:Hep G2 Cells; D006801:Humans; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D009153:Mutagens / Q000528:radiation effects / Q000633:toxicity*; D010316:Particle Size; D013499:Surface Properties; D014025:Titanium / Q000528:radiation effects / Q000633:toxicity*; D014466:Ultraviolet Rays
chemical_list: D009153:Mutagens; C009495:titanium dioxide; D014025:Titanium