Disruption of thyroid hormone regulated proteins and gene expression by polychlorinated biphenyls, polybrominated diphenyl ethers and new flame retardants in residents of an e-waste region

Abstract

Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and new flame retardants (NFRs) are known thyroid hormone (TH) disruptors, but their disrupting mechanisms in humans are not completely understood. In this study, we aimed to explore the disrupting mechanisms of the aforementioned chemicals via

Human exposure to halogenated and organophosphate flame retardants through informal e-waste handling activities - A critical review

“…PBDE concentrations in serum from e-waste recyclers were 1 to 2 orders of magnitude higher than those in non-recyclers whose PBDE concentrations in serum were frequently below limits of detection (Schecter et al, 2018), indicating high occupational exposure of e-waste recyclers to PBDEs. Similar conclusions have been reached in other studies (Eguchi et al, 2015;Guo et al, 2019b;Liang et al, 2016). For instance, in an e-waste recycling site in Wenling, China and an urban area where no e-waste recycling activities were undertaken, 14 PBDE congeners and DBDPE were determined in serum samples taken from e-waste recyclers, non-occupationally-exposed residents of the e-waste site, and urban residents (Liang et al, 2016).…”

“…Moreover, PBDEs and NBFRs are reported thyroid hormone (TH) disruptors (Eguchi et al, 2015;Guo et al, 2019b;Zheng et al, 2017aZheng et al, , 2017b. They have strong binding affinity to thyroidstimulating hormone (TSH), thyroglobulin, thyroxine-binding globulin (TBG), TH receptor α (TRα), and iodothyronine deiodinase I (ID1), and therefore could disrupt TH-regulated proteins and gene expression (Guo et al, 2019b). It is also suggested that PBDEs, NBFRs (e.g., DBDPE, BTBPE, BEH-TBP, etc.…”

“…Such evidence of elevated human exposure has raised concerns about potential adverse health effects on populations impacted by informal e-waste treatment (Akram et al, 2019;Asante et al, 2019;Awasthi et al, 2016Awasthi et al, , 2018Bakhiyi et al, 2018;Orisakwe et al, 2019;Shi et al, 2018). For instance, BFRs are endocrine disruptors (Eguchi et al, 2015;Guo et al, 2018Guo et al, , 2019bZheng et al, 2017aZheng et al, , 2017b, and could exert adverse effects on human semen quality (Yu et al, 2018); while OPFRs have been associated with greater DNA damage (Lu et al, 2017). Moreover, health effects of HFR and OPFR exposure on fetuses and infants are of particular concern due to their substantially weaker resistance and immunity (Bai et al, 2019;Li et al, 2018;Xu et al, 2015;Zheng et al, 2017b).…”

A Halogen Bonding Perspective on Iodothyronine Deiodinase Activity

“…In Dio, a partial explanation for the preference of Sec of Cys is the greater Lewis basicity of the selenolate over the thiolate [71]. In peri-chalcogen-substituted naphthyl-based Dio mimics, strong nucleophiles have higher Dio-like activity (i.e., Se,Se > Se,S > S,S), consistent with the preference for selenium over sulfur An ongoing debate on the driving forces for the XB interaction has raged in the literature [42,66,[74][75][76][77][78][79][80][81][82]. Briefly stated, one side describes XB as driven primarily by electrostatics, where the donor interacts with an area of positive electrostatic potential on the distal end of the R-X bond, commonly called the "σ-hole" [68,83,84].…”

“…An ongoing debate on the driving forces for the XB interaction has raged in the literature [42,66,[74][75][76][77][78][79][80][81][82]. Briefly stated, one side describes XB as driven primarily by electrostatics, where the donor interacts with an area of positive electrostatic potential on the distal end of the R-X bond, commonly called the "σ-hole" [68,83,84].…”