Fate of microplastics and emerging contaminants: Mechanisms of interactions, bioaccumulation and combined toxicity to aquatic organisms

Microplastics (MPs) pose a major environmental challenge owing to their persistence and interactions with emerging contaminants (ECs). Their co-occurrence raises concerns about combined effects on aquatic ecosystems. MPs transport hydrophobic pollutants, affecting water quality. Studies show MPs can adsorb ECs at concentrations up to 106 times higher than their natural levels, increasing bioavailability. MPs and ECs accumulate in aquatic organisms, with evidence of trophic transfer. Their combined toxicity is often greater than their individual effects, causing physiological stress, reduced survival rates and microbial alterations, including enhanced antibiotic resistance. Beyond aquatic ecosystems, MPs and ECs pose risks to human health via bioaccumulation in the food chain. This review analyzes the mechanisms of interactions between MPs and ECs, including uptake, accumulation, and toxicity in aquatic organisms. These findings highlight the need for an integrated environmental impact assessment. Finally, future research directions are proposed, emphasizing key parameters to advance understanding in this field.