Disruption of zebrafish (Danio rerio) reproduction upon chronic exposure to TiO2 nanoparticles

As common engineered nanomaterials, TiO₂ nanoparticles (nTiO₂) are usually perceived as non-toxic, and have already been widely used in many products and applications. Such a perception might have been shaped by some short-term studies that revealed no/low toxicity of nTiO₂ to cells and eco-relevant organisms. However, given the ultimate release of nTiO₂ into the aquatic environment, which can act as a sink for engineered nanoparticles, their long-term impact on the environment and human health is still a concern and deserves more research efforts. Here, for the first time, we demonstrate that chronic exposure of zebrafish to 0.1mgL^-1 nTiO₂, can significantly impair zebrafish reproduction. For instance, there was a 29.5% reduction in the cumulative number of zebrafish eggs after 13weeks of nTiO₂ exposure. Thus, we provided timely information on indicating a serious risk of reproductive impairment of environments contaminated with low levels of nTiO₂ on aquatic organisms, leading to alterations in population dynamics and aquatic ecosystem balance, and thus warrants a careful scrutiny on toxicity assessment of nTiO₂, especially their long-term impact.