| Organohalogenated pollutants(OHPs) are ubiquitous organic pollutants with halogen atoms. Most of OHPs, such as polychlorinated biphenyls(PCBs) and polybrominated diphenyl ethers(PBDEs), have raised environmental concern worldwide because of their persistentence, bioaccumulation, and toxicity as persistent organic pollutants(POPs). PCBs and PBDEs have been lisited in Stockholm Convention. Numerous studies have investigated the environmental occurrence and bioaccumulation of OHPs in aquatic organisms. However, there’re only limited studies focused on the bioaccumulation mechanism in terrestrial organisms.A broad suite of OHPs, including the banned chemicals, namely PCBs and PBDEs, alternatives of PBDEs including dechlorane plus(DP), 1,2-bis(2,4,6-tribromophenoxy)ethane(BTBPE), decabromodiphenyl ethane(DBDPE), and emerging chemicals, namely hexabromocyclododecane(HBCD), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate(TBB), bis-(2-ethylhexyl)-tetrabromophthalate(TBPH), and phosphate flame retardants(PFRs), were investigated in the present thesis. Firstly, a field survey was conducted on OHPs contamination in indoor dust and home-produced eggs in e-waste recycling region. Secondly, based on the previous field studies in e-waste sites, we investigated the behavior of OHPs in comprehensive life stages of adult chicken and chick embryos, including dietary intake, gastrointestinal absorption, tissue distribution, maternal transfer, and embryo development. Thirdly, hepatic metabolism might be an important factor influencing levels and profiles of OHPs in chicken bioaccumulation and embryo development. In order to better understand the hepatic metabolism of OHPs in chicken, we performed in vitro metabolism experiments of BDE 47, BDE 99, and HBCD.The OHP levels and relevant human exposure exposure in e-waste sites were among the highest values reported. The levels of PBDEs, BTBPE, DBDPE, DP, HBCD, TBB, TBPH and PFRs were 685-63300, 28-3870, 1160-45400, 103-3460, 22-1660, 7.5-311, 49-7120 and 2180-33100 ng/g in indoor dust, respectively, and 230-1280, nd-263, 0.54-22, 68-741, 34-318 ng/g lw and nd-0.062, nd-0.46, 1.39-2.15 ng/g ww in eggs, respectively. BDE 209, DBDPE, DP, tri-phenyl-phosphate(TPh P), and tris-(chloropropyl)phosphate(TCPP) were the main chemicals. OHP composition profiles are influenced by the recycling types and intensities of e-wastes in different sites. Egg intake is the more important exposure pathway for PCBs, PBDEs, and DP, while dust ingestion is the more important exposure pathway for DBDPE and PFRs.Soil contributed 78% of PCBs and more than 90% of other chemicals in chyme. Lower-halogenated chemicals are more easily absorbed in gastrointestinal tract of chicken, while levels of BDE 209, DP and DBDPE increased from chyme to feces(ex. DBDPE: chyme 22 ng/g dw, intestinal contents 131 ng/g dw, feces 252 ng/g dw). Levels and profiles of OHPs were different among chicken tissues. DP levels(371 ng/g lw) in serum were significantly higher than those in liver, fat, stomach, and gonad(17.4-96 ng/g lw). PBDEs levels in fat(157 ng/g lw) were significantly lower than those in liver, muscle, and heart(1240-1660 ng/g lw). It’s hypothesized that OHPs firstly distribute among tissues which are well-perfused by bloodstream, and then transported to fat. Only BDE 47 and some PCB congeners could be frequently detected in brain, as a result of blood-brain barrier.During maternal transfer, the pollutant pattern was independent of blood transfer, ovum formation, OHPs in albumen, and potential microbial degradation in eggs. The chiral signatures of PCBs and HBCD between ovum, chicken tissues(muscle, liver, and fat), and eggs indicate that OHPs in eggs mainly come from fat and are transferred with little changes. Fat can better represent the contamination in eggs than other chicken tissues. The levels and profiles of OHPs changed dramatically in the last 7 days during incubation. DBDPE was more persistent than other chemicals in embryos(new-born chick tissues retained 1.5%-3% of PCBs, PBDEs, and HBCD, 9%-14% of DP and BTBPE, and 48.6% of DBDPE from chick embryos), perhaps because DBDPE is most resistant to metabolism. In new-born chicks, liver tended to accumulate chemicals with high log KOW. The chiral signatures of PCBs and HBCD suggest different metabolism pathways in new-born chicks and adult chicken.A series of hydroxylated metabolites were identified in the metabolism of BDE 47, BDE 99 and HBCD by cytochrome P450(CYP 450) enzymes in cat and chicken liver microsomes. 4’-OH-BDE 49(NIH-substitution, 17 pmol, 40% of total metabolites) and 5-OH-BDE 47(m-substitution, 534 pmol, 68% of total metabolites) were the main metabolites of BDE 47 for chicken and cat, while OH-penta-BDEs formed from BDE 99 had values under limit of quantification. HBCD metabolism included both hydroxylation and debromination. The diastereoisomer and enantiomer transformation were not observed in CYP-mediated reactions. |
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