Influence of microplastic-associated biofilms on the bioavailability of a mixture of cadmium and benzo[a]pyrene by the analysis of biomarker gene expression in larval zebrafish

Microplastics (MPs, 1 µm – 5 mm) in aquatic environments undergo complex weathering transformations such as those induced by microbial colonization and biofilm formation, that affect their ability to interact with environmental contaminants (co-contaminants). In this study, the composition of MP biofilms its influence on sorption bioavailability two co-contaminants different physicochemistry, benzo[a]pyrene (B[a]P) cadmium (Cd) a mixture, were assessed. Aqueous-phase was measured assessment biomarker gene expression for these toxicants (cytochrome P450 1A, cyp1a, metallothionein 2, mt2, B[a]P Cd respectively) larval zebrafish, Danio rerio. Significant induction cyp1a mt2 (p < 0.05) observed after exposure mixture Cd, MPs compared joint individual MPs. changes 0.001) resulted same without Biofilms significantly reduced (cyp1a 0.01)) but not (mt2 expression) (HDPE + BF Cd) treatment Cd). Thus, could provide additional interactions B[a]P, new specific active sites surface, bioavailability. Additionally, community included hydrocarbon-degrading bacteria able metabolize hydrophobic chemicals. These data indicated co-contaminants, selectively influenced may have played key role reducing The results study highlight how scenario characterized polymer chemical properties micro-surroundings organisms contaminants' and/or exposure.