Comparison Of Bioavailability And Bioaccessibility For Polybrominated Diphenyl Ethers In Soils

Polybrominated diphenyl ethers (PBDEs) are a class of typical persistent organic pollutants (POPs), which are generally characterized by properties of persistence, bioconcentration, toxicity and a long-rang global transportation. They can lead some adverse effects to human. Bioavailability and bioaccessibility are two important factors in human exposure assessment. The main objectives of this study were to determine the bioavailability and bioaccessibility of PBDEs in soils, and analyzed the relationship between them. It can offer a reference for the optimization of in vitro test simulating gastrointestin digestion.The concentrations of 14 PBDE congeners were determined in 18 soil samples collected from Guiyu, Guangdong. The results showed that PBDEs could be detected in all samples, with the total concentrations of PBDEs ranged from 75.0 to 74740 ng/g dw. Compared with those soils in other studies in domestic and foreign, soils in Guiyu were contaminated seriously by PBDEs. BDE209 was the most abundant congener. It accounted for 75.7-99.0% of the total PBDEs. The present result agreed to the results of other studies. Because BDE209 is the main components of the DecaBDEs, PBDEs in electronic waste mainly was DecaBDEs in Guiyu. In addition, to study the bioavailability and bioaccessibility of PBDEs in soils, the concentrations of PBDEs in selected five soils were repeated measured.Using a mouse model, the mice were exposured to the contaminated soils by oral ingestion. Then, the concentration of PBDEs in different tissues including feces, urine, gastrointestinal tract contents and residual carcass, was measured. The results showed that the bioavailability of PBDE congeners ranged between 0.7% and 48%. The average bioavailability of PBDEs showed an decreasing trend with logKow. In addition, we also found that there was no correlation between the average bioavailability of PBDEs and organic matter contents.The bioaccessibility of PBDEs in the selected five soils were determined via an in vitro digestion method. The bioaccessibility of the congeners ranged from 1.6% to 49.8%. Accorinding to the linear regression analysis, there was a significant linear correlation (y=1.002x+0.634, R2=0.938, p=0.006) between the average bioaccessibility and bioavailability of BDE47,85,99,100 and 183. It indicated that the in vitro gastrointestinal digestion method used in this experiment can be used to predict bioavailability of some PBDE congeners in soil.