Leaching of PBDEs from microplastics under simulated gut conditions: Chemical diffusion and bioaccumulation

Considerable efforts on exposure assessment of microplastics (MPs) as an agent in transport of toxic contaminants have been performed in organisms. However, chemical diffusion of inherent hydrophobic organic contaminants from MPs under simulated gut conditions is poorly examined. The present study examined the transfer kinetics of polybrominated diphenyl ethers (PBDEs) from polystyrene (PS), acrylonitrile butadiene styrene (ABS), and polypropylene (PP) MPs under gut surfactants (sodium taurocholate) at two relevant body temperatures of marine organisms, and evaluated the importance of MP ingestion in bioaccumulation of PBDEs in lugworm by a biodynamic model. Diffusion coefficients of PBDEs range from 5.82 × 10^-23 to 7.96 × 10^-20 m² s^-1 in PS, 5.49 × 10^-23 to 3.45 × 10^-20 m² s^-1 in ABS, and 5.58 × 10^-21 to 5.79 × 10^-17 m² s^-1 in PP, with apparent activation energies in the range of 33-148 kJ mol^-1. The biota-plastic accumulation factors of PBDEs leached from these plastics range from 1.44 × 10^-8 to 7.15 × 10^-5. Although ingestion of MPs with the common size (>0.5 mm) showed the negligible contribution to bioaccumulation of PBDEs in lugworm, their contribution in PBDEs transfer can be increased with gradual breakdown of MPs.