SORPTION OF PBDE IN LOW-DENSITY POLYETHYLENE FILM: IMPLICATIONS FOR BIOAVAILABILITY OF BDE-209

摘要

The coefficients of partitioning (K_(pew)) between low-density polyethylene (LDPE) film (50-μm thickness) and water for 23 polybrominated diphenyl ether (PBDE) congeners were determined based on a regression analysis of sorption kinetics over an extended exposure period (up to 365 d). A curvilinear relationship between log K_(pew) and log K_(OW) (octanol-water partition coefficient) was obtained for the target BDE congeners with the turning point at log K_(OW) approximately 8. Previously obtained dietary uptake efficiencies of BDE congeners in common carp (Cyprinus carpio) were also found to relate curvilinearly to log K_(OW) .In addition, field-measured relative abundances of BDE-209 compiled from previous investigations conducted in the Pearl River Delta of South China were significantly (p< 0.001) higher in abiotic samples (n = 79 from 11 matrices) than in biotic samples (n = 73 from 12 matrices), suggesting the likelihood for reduced bioavailability of BDE-209 in certain biota. Finally, a molecular-scale analysis indicated that the curvilinear relationship between log K_(pew) and log K_(OW) can be attributed to the energy barrier that a molecule has to overcome as it attempts to diffuse into the LDPE structure, which can become significant for larger molecules. Similarly, the reduced bioavailability of BDE-209 in many biological species can be regarded as a reflection of the magnitude of molecular interactions between cell membranes and BDE-209.