An in vitro blood culture for evaluating the genotoxicity of titanium dioxide: the responses of antioxidant enzymes.

Titanium dioxide (TiO2) is extensively used in many industrial areas, including cosmetics, pharmaceutical, paint and paper production. Although the uses of TiO2 have become so widespread, there is limited information concerning its toxicity on humans. However, the genotoxicity of TiO2 remains to be controversial. The possible genotoxic effects of TiO2 have been evaluated in human whole blood cultures (WBCs) related to oxidative status. The blood was processed to examine the following oxidative stress markers: glutathione peroxidase, glutathione reductase, superoxide dismutase and catalase. In addition, the frequencies of sister-chromatid exchanges (SCEs) and micronuclei (MN) were scored as genetic endpoints. Different concentrations of TiO2 (1, 2, 3, 5, 7.5 and 10 microM) were tested. From the results, it appeared that TiO2 was able to induce genotoxic effects, as observed by the increases found in SCE and MN frequencies in TiO2-treated cultures. Present results also show that treatments with TiO2 promoted oxidative stress in human WBC with an increase in concentrations. In conclusion, our data indicate that TiO2 can enhance oxidative stress-mediated DNA damage in vitro.