Urinary bromophenol glucuronide and sulfate conjugates: Potential human exposure molecular markers for polybrominated diphenyl ethers

Abstract

One possible source of urinary bromophenol (BP) glucuronide and sulfate conjugates in mammalian animal models and humans is polybromodiphenyl ethers (PBDEs), a group of additive flame-retardants found ubiquitously in the environment. In order to study the correlation between levels of PBDEs in human blood plasma and those of the corresponding BP-conjugates in human urine, concentrations of 17 BDE congeners, 22 OH-BDE and 13 MeO-BDE metabolites, and 3 BPs in plasma collected from 100 voluntary donors in Hong Kong were measured by gas chromatograph tandem mass spectrometry (GC–MS). Geometric mean concentration of ΣPBDEs, ΣOH-BDEs, ΣMeO-BDEs and ΣBPs in human plasma were 4.45ngg−1lw, 1.88ngg−1lw, 0.42ngg−1lw and 1.59ngg−1lw respectively. Concentrations of glucuronide and sulfate conjugates of 2,4-dibromophenol (2,4-DBP) and 2,4,6-tribromophenol (2,4,6-TBP) in paired samples of urine were determined by liquid chromatography tandem triple quadrupole mass spectrometry (LC–MS/MS). BP-conjugates were found in all of the parallel urine samples, in the range of 0.08–106.49μgg−1-creatinine. Correlations among plasma concentrations of ΣPBDEs/ΣOH-BDEs/ΣMeO-BDEs/ΣBPs and BP-conjugates in urine were evaluated by multivariate regression and Pearson product correlation analyses. These urinary BP-conjugates were positively correlated with ΣPBDEs in blood plasma, but were either not or negatively correlated with other organobromine compounds in blood plasma. Stronger correlations (Pearson’s r as great as 0.881) were observed between concentrations of BDE congeners having the same number and pattern of bromine substitution on their phenyl rings in blood plasma and their corresponding BP-conjugates in urine.