Chiral signatures of polychlorinated biphenyls in serum from e-waste workers and their correlation with hydroxylated metabolites

Elevated concentrations of polychlorinated biphenyls (PCBs) found in environmental media and biota from typical e-waste dismantling sites have raised concerns regarding their human body burden and potential negative health effects. In the present study, the enantiomeric compositions of three typical chiral congeners (PCB-95, PCB-132, and PCB-149) were measured in 24 serum samples from e-waste workers by using gas chromatography coupled to triple quadrupole tandem mass spectrometry. The mean enantiomer fractions (EFs) of chiral congeners in serum from the workers were 0.655 ± 0.103, 0.679 ± 0.164, and 0.548 ± 0.095 for PCB-95, PCB-132, and PCB-149, respectively. The (+) enantiomers of PCB-95, PCB-132, and PCB-149 were enantioselectively enriched in serum. Significant positive correlations were observed between the EF of the chiral congener PCB-95 and the total concentration of OH-PCBs, suggesting that EF values of chiral PCBs could be used to indicate the extent of biological metabolism. In addition, the EF of PCB-95 in serum samples increased with increasing work duration of the e-waste workers, thus demonstrating the usefulness of EF values of chiral PCBs as tracers of human exposure to PCBs. Because of the enantioselective enrichment of (+) enantiomers of PCB-95, PCB-132, and PCB-149, further studies are needed to explore the metabolism and toxicity of chiral contaminants in humans.