Leaching of polybrominated diphenyl ethers from microplastics in fish oil: Kinetics and bioaccumulation

Microplastics (MPs) contain high levels of polybrominated diphenyl ethers (PBDEs), which can leach to organism tissues upon ingestion, thereby leading to increased chemical exposure. However, leaching kinetics of inherent contaminants from ingested MPs are poorly studied. The present study characterized the leaching kinetics of PBDEs from sub-millimeter sized MPs in fish oil at relevant body temperatures for marine organisms and assessed exposure risk of MPs for cod fish by a biodynamic model. Diffusion coefficients (D-p) of PBDEs are in the ranges of 1.98 x 10(-19)-2.35 x 10(-16) m(2).s(-1) in polystyrene, 1.89 x 10(-20)-2.07 x 10(-18) m(2).s(-1) in acrylonitrile butadiene styrene, and 4.26 x 10(-18)-1.72 x 10(-15) m(2).s(-1) in polypropylene. A linear function obtained between log D-p of BDE-209 and glass-transition temperature of MPs allows estimation of D-p of BDE-209 contained in other common types of MPs present in the gastrointestinal lipid. The biota-plastic accumulation factors of PBDEs for three plastics were in the range of 4.77 x 10(-14)-4.03 x 10(-7). Although bioaccumulation of MPs-affiliated PBDEs is accelerated by oil in the gastrointestinal tract, the modeled steady-state concentrations of PBDEs in cod tissue lipid through ingestion of MPs under the most likely conditions were below the lower end of the global PBDE concentration, implicating that ingestion of MPs by organisms remains a negligible pathway in general.

Automated summary

This study found that PBDEs in microplastics can leach upon ingestion, but the leaching kinetics of inherent contaminants from ingested microplastics are poorly understood. Although the bioaccumulation of PBDEs in fish oil can be accelerated in the gastrointestinal tract, the steady-state concentrations of PBDEs in cod tissue lipid through ingestion of microplastics were found to be below the lower end of the global PBDE concentration, suggesting that ingestion of microplastics by organisms remains a negligible pathway.