Environmental risk of titanium dioxide nanoparticle and cadmium mixture: developmental toxicity assessment in zebrafish (Danio rerio)

The environmental health impact of titanium dioxide nanoparticles (TiO₂ NPs) is of emerging concern, but their effects and ecotoxicity resulting from the interaction between TiO₂ NPs and metals, such as cadmium (Cd), on aquatic organisms remain limited. Thus, the current study aimed to evaluate the ecotoxic effects of TiO₂ NPs and Cd (alone or in co-exposure) on zebrafish embryos and larvae, based on using multiple biomarkers. Embryos were exposed to environmentally relevant TiO₂ NPs (0.1, 1.0, and 10 µg L⁻¹) and Cd (10 µg L⁻¹) concentrations, either alone or in a mix, for 168 h, whereas the control group was kept in reconstituted water. Results showed that the isolated TiO₂ NPs have low toxicity to zebrafish embryos and larvae. However, Cd — alone or in co-exposure with TiO₂ NPs — induced toxic effects in zebrafish, such as cardiotoxicity, as well as morphological and morphometric changes. The present study has shown TiO₂ NPs/Cd interactive effects, including decreased toxicity, on the assessed models. Results have evidenced the potential environmental risk of the nanoparticle and metal mixtures, mainly at early vertebrate developmental stages.