Identification of SulfatedMetabolites of 4-Chlorobiphenyl(PCB3) in the Serum and Urine of Male Rats.

Polychlorinated biphenyls (PCBs) are legacy pollutantsthat exerttoxicities through various mechanisms. In recent years exposure toPCBs via inhalation has been recognized as a hazard. Those PCBs withlower numbers of chlorine atoms (LC-PCBs) are semivolatile and havebeen reported in urban air, as well as in the indoor air of olderbuildings. LC-PCBs are bioactivated to phenols and further to quinoneelectrophiles with genotoxic/carcinogenic potential. We hypothesizedthat phenolic LC-PCBs are subject to conjugation and excretion inthe urine. PCB3, often present in high concentrations in air, is aprototypical congener for the study of the metabolism and toxicityof LC-PCBs. Our objective was to identify metabolites of PCB3 in urinethat could be potentially employed in the estimation of exposure toLC-PCBs. Male Sprague–Dawley rats (150–175 g) were housedin metabolism cages and received a single intraperitoneal injectionof 600 μmol/kg body weight of PCB3. Urine was collected every4 h; rats were euthanized at 36 h; and serum was collected. LC/MSanalysis of urine before and after incubation with β-glucuronidaseand sulfatase showed that sulfate conjugates were in higher concentrationsthan glucuronide conjugates and free phenolic forms. At least twomajor metabolites and two minor metabolites were identified in urinethat could be attributed to mercapturic acid metabolites of PCB3.Quantitation by authentic standards confirmed that approximately 3%of the dose was excreted in the urine as sulfates over 36 h, withpeak excretion occurring at 10–20 h after exposure. The majormetabolites were 4′PCB3sulfate, 3′PCB3 sulfate, 2′PCB3sulfate, and presumably a catechol sulfate. The serum concentrationof 4′PCB3 sulfate was 6.18 ± 2.16 μg/mL. This isthe first report that sulfated metabolites of PCBs are formed in vivo. These findings suggest a prospective approach forexposure assessment of LC-PCBs by analysis of phase II metabolitesin urine. [ABSTRACT FROM AUTHOR]