Nano-titanium dioxide induced genotoxicity and histological lesions in a tropical fish model, Nile tilapia (Oreochromis niloticus).

This study evaluated potential genotoxic and histopathological effects of nano-TiO2 (0.1, 0.5 and 1mg/L) in Nile tilapia over 7, 14 and 21 days of exposure. Bulk TiO2 (1mg/L) along with controls was used for comparison. Comet assay revealed that nano-TiO2 can induce erythrocytic DNA damage in a concentration dependent manner. However, micronuclei induction was observed only at the lowest concentration. Elevated organ damage indices indicate nano-TiO2 induced histological alterations in liver and intestine. Severe histological alterations induced by nano-TiO2 in the fish were necrosis of hepatic parenchyma and intestinal mucosa. Bulk TiO2 exposure had no effect on the histological structure of the intestine but increased liver damage indices and erythrocytic DNA damage compared to the controls indicating dissolved form of TiO2 is not biologically inert. More research efforts are needed to generate in vivo toxicity data on realistic levels of nano-TiO2 and bulk TiO2 for environmental risk assessments.