Genotoxicity evaluation of titanium dioxide nanoparticles using the Ames test and Comet assay§

Authors

  • Robert S. Woodruff,

    1. Division of Microbiology, Arkansas Regional Laboratory, U.S. Food and Drug Administration, Jefferson, AR, USA
    Search for more papers by this author
    • These authors contributed equally to this work and are the joint first authors.

  • Yan Li,

    1. Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, USA
    Search for more papers by this author
    • These authors contributed equally to this work and are the joint first authors.

  • Jian Yan,

    1. Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, USA
    Search for more papers by this author
  • Michelle Bishop,

    1. Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, USA
    Search for more papers by this author
  • M. Yvonne Jones,

    1. Nanotechnology Facility, National Center for Toxicological Research, U.S. Food and Drug Administration, AR, USA
    Search for more papers by this author
  • Fumiya Watanabe,

    1. Nanotechnology Center, Applied Science Department, University of Arkansas at Little Rock, Little Rock, AR, USA
    Search for more papers by this author
  • Alexandru S. Biris,

    1. Nanotechnology Center, Applied Science Department, University of Arkansas at Little Rock, Little Rock, AR, USA
    Search for more papers by this author
  • Penelope Rice,

    1. Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD, USA
    Search for more papers by this author
  • Tong Zhou,

    1. Center for Veterinary Medicine, U.S. Food and Drug Administration, Rockville, MD, USA
    Search for more papers by this author
  • Tao Chen

    Corresponding author
    • Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, USA
    Search for more papers by this author

  • §

    This article is not an official guidance or policy statement of the U.S. Food and Drug Administration (FDA). No official support or endorsement by the U.S. FDA is intended or should be inferred.

Tao Chen, 3900 NCTR Rd, Jefferson, AR 72079, USA. E-mail: tao.chen@fda.hhs.gov

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. Published 2012. This article is a US Government work and is in the public domain in the USA.

Ancillary