Genotoxic effects of nanosized and fine TiO2

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Abstract
The in-vitro genotoxicity of nanosized TiO2 rutile and anatase was assessed in comparison with fine TiO2 rutile in human bronchial epithelial BEAS 2B cells using the single-cell gel electrophoresis (comet) assay and the cytokinesis-block micronucleus test. BEAS 2B cells were exposed to eight doses (1—100 μg/cm2) of titanium(IV) oxide nanosized rutile (>95%, 2 coating; 10 × 40 nm), nanosized anatase (99.7%; 2 for fine rutile and 10 μg/cm 2 for nanosized anatase. Nanosized rutile showed a significant induction in DNA damage only at 80 μg/cm2 in the 24-h treatment and at 80 and 100 μg/ cm2 in the 72-h treatment (with a dose-dependent effect). Only nanosized anatase could elevate the frequency of micronucleated BEAS 2B cells, producing a significant increase at 10 and 60 μg/cm 2 after the 72-h treatment (no dose-dependency). At increasing doses of all the particles, MN analysis became difficult due to the presence of TiO2 on the microscopic slides. In conclusion, our studies in human bronchial epithelial BEAS 2B cells showed that uncoated nanosized anatase TiO2 and fine rutile TiO2 are more efficient than SiO 2-coated nanosized rutile TiO2 in inducing DNA damage, whereas only nanosized anatase is able to slightly induce micronuclei.