Polystyrene microplastics (PS-MPs) harness copper presence and promote impairments in early zebrafish (Danio rerio) larvae: Developmental, biochemical, transcriptomic approaches and nontargeted metabolomics approaches

Due to their large specific surface area and strong hydrophobicity, microplastics (MPs) are highly susceptible to adsorb environmental pollutants, of which heavy metals (HMs) are the most representative inorganic pollutants. However, there is controversy in different studies as to whether the toxic effects of the combined action of MPs and HMs on zebrafish larvae are antagonistic or synergistic. Herein, we firstly evaluated the combined effects of 10 μm polystyrene MPs (PS-MPs) on zebrafish larvae after exposure for 96 h at two different concentrations (5 mg/L, 0.5 mg/L) and Cu²⁺ (0.05 mg/L). Our study primarily showed that the combined exposure of PS-MPs and Cu²⁺ could induce developmental toxicity, oxidative stress, immunotoxicity and neurotoxicity. Furthermore, LC/MS-based nontargeted metabolomics analysis demonstrated that the combined exposure of PS-MPs with Cu²⁺ induced metabolic disturbances. Furthermore, our results showed that the combined exposure of 10 μm PS-MPs with Cu²⁺ exhibited a synergistic effect on the toxicity of zebrafish larvae. In conclusion, this study provides a reference for future research related to combined exposure of PS-MPs and Cu²⁺ on fish.