title: Genotoxicity evaluation of titanium dioxide nanoparticles using the Ames test and Comet assay.
abstract: Titanium dioxide nanoparticles (TiO2-NPs) are being used increasingly for various industrial and consumer products, including cosmetics and sunscreens because of their photoactive properties. Therefore, the toxicity of TiO2-NPs needs to be thoroughly understood. In the present study, the genotoxicity of 10nm uncoated sphere TiO2-NPs with an anatase crystalline structure, which has been well characterized in a previous study, was assessed using the Salmonella reverse mutation assay (Ames test) and the single-cell gel electrophoresis (Comet) assay. For the Ames test, Salmonella strains TA102, TA100, TA1537, TA98 and TA1535 were preincubated with eight different concentrations of the TiO2-NPs for 4 h at 37 °C, ranging from 0 to 4915.2 µg per plate. No mutation induction was found. Analyses with transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) showed that the TiO2-NPs were not able to enter the bacterial cell. For the Comet assay, TK6 cells were treated with 0-200 µg ml(-1) TiO2-NPs for 24 h at 37 °C to detect DNA damage. Although the TK6 cells did take up TiO2-NPs, no significant induction of DNA breakage or oxidative DNA damage was observed in the treated cells using the standard alkaline Comet assay and the endonuclease III (EndoIII) and human 8-hydroxyguanine DNA-glycosylase (hOGG1)-modified Comet assay, respectively. These results suggest that TiO2-NPs are not genotoxic under the conditions of the Ames test and Comet assay.
authors: Division of Microbiology, Arkansas Regional Laboratory, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA.
authors: Robert S
authors: RS
authors: Woodruff
authors: Yan
authors: Y
authors: Li
authors: Jian
authors: J
authors: Yan
authors: Michelle
authors: M
authors: Bishop
authors: M Yvonne
authors: MY
authors: Jones
authors: Fumiya
authors: F
authors: Watanabe
authors: Alexandru S
authors: AS
authors: Biris
authors: Penelope
authors: P
authors: Rice
authors: Tong
authors: T
authors: Zhou
authors: Tao
authors: T
authors: Chen
mesh_terms: D002460:Cell Line; D020552:Comet Assay / Q000379:methods*; D004249:DNA Damage; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects*; D046529:Microscopy, Electron, Transmission; D009152:Mutagenicity Tests; D053758:Nanoparticles / Q000633:toxicity*; D012486:Salmonella typhimurium / Q000187:drug effects*; D013052:Spectrometry, X-Ray Emission; D014025:Titanium / Q000633:toxicity*
chemical_list: C009495:titanium dioxide; D014025:Titanium