Hydroxylated Metabolites of Polybrominated Diphenyl Ethers in Human Blood Samples from the United States

Abstract

BackgroundA previous study from our laboratory showed that polybrominated diphenyl ethers (PBDEs) were metabolized to hydroxylated PBDEs (HO-PBDEs) in mice and that para-HO-PBDEs were the most abundant and, potentially, the most toxic metabolites.ObjectiveThe goal of this study was to determine the concentrations of HO-PBDEs in blood from pregnant women, who had not been intentionally or occupationally exposed to these flame retardants, and from their newborn babies.MethodsTwenty human blood samples were obtained from a hospital in Indianapolis, Indiana, and analyzed for both PBDEs and HO-PBDEs using electron-capture negative-ionization gas chromatographic mass spectrometry.ResultsThe metabolite pattern of HO-PBDEs in human blood was quite different from that found in mice; 5-HO-BDE-47 and 6-HO-BDE-47 were the most abundant metabolites of BDE-47, and 5′-HO-BDE-99 and 6′-HO-BDE-99 were the most abundant metabolites of BDE-99. The relative concentrations between precursor and corresponding metabolites indicated that BDE-99 was more likely to be metabolized than BDE-47 and BDE-100. In addition, three bromophenols were also detected as products of the cleavage of the diphenyl ether bond. The ratio of total hydroxylated metabolites relative to their PBDE precursors ranged from 0.10 to 2.8, indicating that hydroxylated metabolites of PBDEs were accumulated in human blood.ConclusionsThe quite different PBDE metabolite pattern observed in humans versus mice indicates that different enzymes might be involved in the metabolic process. Although the levels of HO-PBDE metabolites found in human blood were low, these metabolites seemed to be accumulating.

Uptake, translocation and biotransformation kinetics of BDE-47, 6-OH-BDE-47 and 6-MeO-BDE-47 in maize (Zea mays L.)

“…The rate of transformation from 6-OH-BDE-47 to MeO-PBDEs was twice as high as that from 6-MeO-BDE-47 to OH-PBDEs, suggesting that 6-OH-BDE-47 was more prone to transform in maize than 6-MeO-BDE-47. Additionally, though the isomerization rates of 6-OH-BDE-47 and 6-MeO-BDE-47 were low, coexistence of their isomers in biotic (Lacorte and Ikonomou, 2009;Malmv€ arn et al, 2008;Qiu et al, 2009) and abiotic (Kelly et al, 2008;Wang et al, 2014;Zhang et al, 2012) media suggested the formation of OH-PBDEs and MeO-PBDEs, through isomerization could not be ignored.…”

Characterization of polybrominated diphenyl ethers (PBDEs) and hydroxylated and methoxylated PBDEs in soils and plants from an e-waste area, China

“…However, ortho-substituted OH-PBDEs and MeO-PBDEs have also been detected in PBDE exposure plants and animals (Qiu et al, 2007; Wang et al, 2012;Sun et al, 2013b), and meta-and parasubstituted compounds have also been found in environmental matrices Qiu et al, 2009;Sun et al, 2013a;Zhang et al, 2012). In the present study the ortho-, meta-and para-substituted OH-PBDEs and MeO-PBDEs were all detected in the soil and plant samples with 6-OH-BDE47, 6-OH-BDE85, 2 0 -OH-BDE3, 6 0 -OH-BDE99, 3 0 -OH-BDE7, 6-MeO-BDE85 and 2 0 -MeO-BDE3 as the major congeners (Figs.…”

Molecular toxicology of polybrominated diphenyl ethers: nuclear hormone receptor mediated pathways

“…3 In addition, the hydroxylated PBDE (OH-PBDE) metabolites and methoxylated PBDE (MeO-PBDE) analogues have also been detected in human bodies. 4,5 The source of the OH-PBDE metabolites and MeO-PBDE analogues can be either intake from marine food or metabolically derived biotransformation of PBDEs by humans themselves. 6 Because of their persistence in the environment and bio-accumulation in the food chain, even low levels of PBDEs might pose great risk to human health.…”