Identification of hydroxylated octa- and nona-bromodiphenyl ethers in human serum from electronic waste dismantling workers.

Previous studies have reported high serum concentrations of polybrominated diphenyl ethers, especially decabromodiphenyl ether (BDE-209), in the residents of an electronic waste (e-waste) dismantling site in Guiyu town, South China. In the present study, human serum samples in this region were collected and pooled for the identification of hydroxylated diphenyl ethers (OH-PBDEs). Three OH-PBDEs, including two hydroxylated octabromodiphenyl ethers (OH-octaBDEs, 6-OH-BDE196 and 6-OH-BDE199) and one hydroxylated nonabromodiphenyl ether (OH-nonaBDE, 6'-OH-BDE206), were first structurally identified. Identification was done by coeluting a mixture of synthetic authentic standards with the methylated OH-PBDEs from the pooled samples using two gas chromatography columns with different polarities. The results were supported by full scan mass spectrometric data in electron capture negative ionization mode. All three OH-PBDE metabolites had hydroxy groups substituted in the ortho position. These results indicate that hydroxylated higher brominated diphenyl ethers such as OH-octaBDEs and OH-nonaBDEs can accumulate in human blood. The results suggest that higher brominated diphenyl ethers could be oxidatively metabolized into OH-PBDEs in humans. Because low brominated OH-PBDEs can also be detected in abiotic media, further investigations are needed to determine the presence of higher brominated OH-PBDEs in the environment in this region.