Sorption of Oxybenzone onto Polystyrene Microplastics Influences Bioavailability and Early-Life Development in Zebrafish (Danio rerio)

Oxybenzone (BP-3) and polystyrene microplastics (PS MPs) are pervasive aquatic contaminants whose combined biological effects remain insufficiently characterized. This study investigated co-exposure to BP-3 and PS MPs in zebrafish embryos (Danio rerio), focusing on developmental endpoints, tissue bioaccumulation, and time-dependent sorption behavior. Embryos were exposed to 0.10–1.50 mg/L BP-3 for 96 h in the presence of PS MPs. Mortality, developmental abnormalities, and tissue BP-3 concentrations were measured, and chemical analysis was performed by HPLC-DAD. Although mortality was not significantly affected, embryos exhibited developmental abnormalities, particularly in swim bladder formation. Tissue BP-3 accumulation increased with exposure concentration. The influence of PS MPs on BP-3 uptake was concentration-dependent: at lower BP-3 exposures, PS MPs reduced tissue accumulation, whereas at higher exposures this reduction became negligible or was no longer observed. This suggests a dual role for PS MPs: mitigating direct aqueous exposure by sequestering BP-3 yet simultaneously acting as potential vectors for its environmental persistence and trophic transfer through alternative pathways. Independent time-resolved experiments showed rapid BP-3 removal from the aqueous phase in the presence of PS MPs, with early stabilization consistent with rapid partitioning behavior. These findings highlight the complex interactions between emerging contaminants and MPs, underscoring the need for further research into their ecological implications.