Plastic as a carrier of POPs to aquatic organisms. A model analysis

It has been hypothesised that persistent organic pollutants (POPs) in microplastic may pose a risk to aquatic organisms. Here, we present a conceptual model for bioaccumulation of POPs including uptake from water, food and ingested plastic. The model accounts for dilution of exposure concentration by sorption of POPs to plastic (POP 'dilution'), increased bioaccumulation by ingestion of plastic containing POPs ('carrier'), and decreased bioaccumulation by ingestion of clean plastic ('cleaning'). A dynamically modelled absorption efficiency from plastic is proposed, which is calculated from particle size, POP polymer diffusivities, the time variable gradient between plastic and organism POP concentrations, and gut retention time. The model is parameterised for the lugworm Arenicola marina and evaluated against recently published polychlorinated biphenyl (PCB) bioaccumulation data for this species from laboratory bioassays with polystyrene microplastic. Further scenarios include polyethylene