Assesment of genotoxic effects of Titanium dioxide and Zinc oxide nanoparticles in human lymphocytes in vitro

Titanium dioxide nanoparticles (TiO2 NPs) and zinc oxide nanoparticles (ZnO NPs), used in this study, were observed to be spherical in shape and contained particles ranging from 10-300 nm by scanning electron microscopy. These nanoparticles were found to be negatively charged and the mean hydrodynamic diameters were found to be 804.30±15.06 nm for TiO2 NPs and 495.80±51.15 nm for ZnO NPs by dynamic light scattering. 20, 40, 60, 80 ve 100 µg/ml concentrations of TiO2 NPs and 1, 5, 10, 20 ve 30 µg/ml concentrations of ZnO NPs were used to assess genotoxic effects. TiO2 NPs significantly increased the frequency of chromosomal aberrations (CAs) at two lowest concentrations (20 ve 40 ?g/ml) at 24 h treatment, however they did not show a significant increase at 48 h treatment. ZnO NPs significantly increased the frequency of CAs at two highest concentrations (20 and 30 ?g/ml) at 24 h and at all concentrations at 48 h treatment. TiO2 NPs significantly increased the frequency of sister chromatid exchanges (SCEs) at both treatment periods compared to negative control. These increases were significant at 20, 60 ve 100 µg/ml concentrations for 24 h treatment and, 20, 60, 80 ve 100 µg/ml concentrations for 48 h treatment compared to solvent control. ZnO NPs, increased the frequency of sister chromatid exchanges (SCEs) at both treatment periods in a dose dependent manner. These increases were significant at the three highest concentrations for 24 h and at the two highest concentrations for 48 h treatment. TiO2 NPs induced a non-significant increase in the the frequency of micronuclei at three lowest concentrations. ZnO NPs increased the frequency of MN at all concentrations, however these increases were significant at the two highest concentrations (20 and 30 ?g/ml). TiO2 NPs caused reduction in mitotic index at 24 h treatment compared to control. However these reductions were significant at 60 and 80 µg/ml concentrations. TiO2 NPs did not induced a significant effect on mitotic index at 48 h treatment. ZnO NPs reduced mitotic index at both treatment periods. These decreases were significant at 5, 10 and 30 µg/ml concentrations at 24 h and 30 µg/ml concentrations at 48 h treatments. While TiO2 NPs did not show any effect on replication index, ZnO NPs caused a non-significant decrease at the highest concentrations at both treatment periods. Neither TiO2 NPs nor ZnO NPs effect nuclear division index. TiO2 NPs caused a significant increase in tail lenght at the highest concentration (100 µg/ml) compared to control, however they did not show a significant effect on tail intensity and tail moment. Tail intensity reduced significantly at the highest concentrations with ZnO NPs treatment. Although tail intensity and tail moment displayed similar decreases and increases, tail lenght increased significantly at 5 and 20 µg/ml concentrations in ZnO NPs treatment. These results show that TiO2 NPs have a relatively weak genotoxic effect, by contrast, ZnO NPs have a strong genotoxic effect as well as cytotoxic effect at high concentrations.