Hazard of mixture of pollutants to aquatic organisms: evaluation of the effects of imidacloprid, tebuconazole, and microplastics in the RTL-W1 cell line.

Pesticides and microplastics coexist in aquatic ecosystems, creating complex exposure scenarios that remain insufficiently explored in ecotoxicology. This study evaluated the cytotoxic and enzymatic responses of RTL-W1 cells exposed to Imidacloprid (IMI), Tebuconazole (TEB), and polyethylene microplastics (PE-MPs), individually and in mixture scenarios. Cytotoxicity was assessed using Alamar Blue, CFDA-AM, and Neutral Red Uptake assays, while cytochrome P450-1A (CYP1A) activity was evaluated through the EROD assay. Isolated exposures to IMI, TEB, and PE-MPs were not cytotoxic. In contrast, pesticide mixtures (IMI +TEB) affected all endpoints, suggesting potential interactive effects such as additive or synergistic interactions. High concentrations of TEB markedly suppressed EROD activity, whereas a combination of high IMI and low TEB concentrations induced CYP1A activity. When PE-MPs were included in the mixtures, lysosomal function was the most sensitive endpoint, particularly in combinations containing TEB. These findings provide insights into contaminant interactions in fish cells and their effects.