Effects of in vitro exposure to titanium dioxide on DNA integrity of bottlenose dolphin (Tursiops truncatus) fibroblasts and leukocytes

In the present study, the genotoxic potential of nanosized TiO2 anatase and micro-sized rutile on bottlenose dolphin (Tursiops truncatus) fibroblasts and leukocytes was investigated. Human and mouse cells were also studied in order to compare susceptibility to TiO2 in different mammalian species. Cell lines were exposed for 4, 24, and 48 h to different concentrations of TiO2 (20, 50, 100, 150 μg/ml) and DNA damage was investigated by single cell gel electrophoresis (Comet assay). Both anatase and rutile induced increased DNA damage, even though statistically significant effects were scattered according to species and cell lines. Bottlenose dolphin leukocytes and murine fibroblasts exhibited increased DNA damage after rutile exposure at some doses/times, while human fibroblasts showed a significant dose-response effect after a 4 h exposure to anatase. Human leukocytes were tolerant to both anatase and rutile. Ultrastructural investigation showed that TiO2 particles entered the cell and were compartmentalized within membrane-bound vesicles.