Polybrominated diphenyl ethers and polychlorinated biphenyls in freshwater fish from Taihu Lake, China: their levels and the factors that influence biomagnification.

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs), two types of persistent organic pollutants that have been used widely, can be released into the environment and accumulate in organisms. To obtain a better understanding of the biomagnification of PBDEs and PCBs in fish, as well as the influences on biomagnification by fish size and physical properties of PBDEs and PCBs, a total of 200 samples of 24 fish species were collected and analyzed from Taihu Lake, the second largest freshwater lake in China. The concentrations of PBDEs and PCBs ranged from 8.59 to 74.28 ng/g lipid weight (lw) and from 10.30 to 165.20 ng/g lw, respectively. Trophic magnification factors (TMFs) were used to estimate the PBDE and PCB biomagnification potentials. The TMF values of PBDEs and PCBs ranged from 0.78 to 2.95 and from 0.92 to 2.60, respectively. Most of the TMFs were greater than 1, indicating that these contaminants were biomagnified in food chains. Fish size might influence the biomagnification evaluation, because different sized fish had different lipid content, leading to different lipid-based concentrations of PBDEs and PCBs. Parabolic relationships were observed between the TMFs and logK(OW) , as well as between the TMFs and the molecular volumes of PBDE and PCB congeners. The congeners with logK(OW) values of approximately 7 or molecular volumes of approximately 8 × 10⁻5 nm³ had the greatest biomagnification potentials. Compared to molecular weight, molecular volume seems to be the better standard for analyzing the influence of molecular size on biomagnification.

Polybrominated diphenyl ethers in food and associated human daily intake assessment considering bioaccessibility measured by simulated gastrointestinal digestion.

The concentrations of PBDEs in 299 vegetable and animal-based food samples of 31 species, collected in Shanghai, China, and the bioaccessibility of PBDEs in part of the samples were determined. The PBDE concentrations ranged from 0 to 1245.4pgg(-1) with animal-based food containing more PBDEs than vegetables. The bioaccessibility of PBDEs, determined by a method simulating human gastrointestinal digestion process, were from 2.6% to 39.9% in vegetables, and from 5.2% to 105.3% in animal-based food. For animal-based food, good correlations were observed between the bioaccessibility of PBDEs and the fat content, thus the fat content in animal-based food was able to be used to estimate the bioaccessibility of PBDEs. The total daily intake of PBDEs via ingestion of vegetables and animal-based food for an average Shanghai resident was estimated as 13235.7 and 13668.0pg d(-1), respectively, but the amounts available for human absorption were reduced to 2674.4 and 4316.6pgd(-1) after the PBDE bioaccessibility was considered. Finally, the contributions of different food groups to the total daily intake of PBDEs were evaluated. The results revealed that, when not considering the bioaccessibility of PBDEs, vegetables were the leading contributor (49.2%), followed by fish (34.0%). However, the sequence was reversed after the PBDE bioaccessibility was taken into account. The results indicated that human exposure to PBDEs via food ingestion might have been significantly overestimated and the exposure assessment could be misleading if the bioaccessibility of PBDEs was not considered.