Effect of Coexposure to Zinc Oxide Nanoparticles (ZnO NPs) on the Bioaccumulation and Toxicity of Tebuconazole in Zebrafish (Danio rerio)

The frequent occurrence of pesticides and nanoparticles in aquatic environments raises ecological concerns. Tebuconazole (TEB) is a widely used triazole fungicide, and zinc oxide nanoparticles (ZnO NPs) are one of the commonly used engineered nanoparticles. Both are frequently detected in the aquatic environment, yet their combined effects on aquatic organisms remain inadequately understood. In this study, we investigated the impacts of coexposure to environmentally relevant concentrations of ZnO NPs on the toxicity and bioaccumulation of TEB in zebrafish ( Danio rerio ). The 96-h median lethal concentration (LC 50 ) of TEB to zebrafish was 6.45 mg/L. Coexposure to ZnO NPs (1–100 mg/L) led to a slight increase in acute toxicity of TEB. Long-term (28-day) coexposure to environmentally relevant concentrations of TEB and ZnO NPs exacerbated oxidative stress and apoptosis, decreased the activity of the detoxification enzyme carboxylesterase, and upregulated cytochrome P450 activity. Additionally, ZnO NPs did not enhance the accumulation of TEB but prolonged its clearance and altered its bioaccumulation pattern. These results indicate that the presence of ZnO NPs may increase the potential risk associated with TEB exposure in zebrafish, underscoring the need for further investigation of the interactive effects of pesticides and engineered nanomaterials in aquatic ecosystems.