Effects of titanium dioxide nano-particles on growth and some histological parameters of zebrafish (Danio rerio) after a long-term exposure

According to some previous studies, titanium dioxide (TiO2) nanoparticles (NPs) would be of low to medium ecological toxicity in short-term tests. But the long-term risks of TiO2 NPs that is currently unknown. In this study, we used the zebrafish (Danio rerio) as in vivo model to assess the chronic toxicity of TiO2 NPs. Our results revealed that there are obvious adverse effect to zebrafish, including concentration-dependent and time-dependent inhibition of growth and decrease the liver weight ratio of zebrafish. Meanwhile, only the gills displayed histopathologic change including thickening of oedema and the gill lamellae. ICP-MS examination showed that TiO2 NPs were accumulated and distributed in gill, liver, heart as well as brain. Our present study suggested that the TiO2 NPs could translocate among organs and pass through the blood–brain and the blood–heart barrier after long-term exposure. Given the widespread use of TiO2 NPs, a systematic, coherent, and tested foundation for managing the uncertain health and environmental aspects of TiO2 NPs is necessary.