Although polychlorinated biphenyls are no longer sold as commercial mixtures, they are still being produced through modern manufacturing processes. We have previously shown that non-Aroclor PCB11 is prevalent in indoor and outdoor air, sediment, and detected in human serum. Here we report the prevalence of non-Aroclor PCB congeners (≤0.20 weight percent in Aroclor) in human serum collected from urban and rural adolescents and their mothers. We hypothesized that additional non-Aroclors congeners are present in serum. Sera were extracted and detected for 209 PCBs using gas chromatography-tandem mass spectrometry. A list of 70 non-Aroclor PCB congeners was determined by measurement of original Aroclors. PCB 11, 14, 35 and 209 are the major dominating and most frequently detected congeners. PCB 14 and 35 have not been previously reported for environmental matrices. Adolescents have significantly lower total non-Aroclor PCBs concentration than mothers in East Chicago (p<0.001) and Columbus Junction (p=0.008). There are significant differences in non-Aroclor PCBs between East Chicago community and Columbus Junction community (p<0.001). Non-Aroclor PCBs represent an average of 10% (and up to 50%) of total PCBs measured in serum. An average of 50% (and up to 100%) of these concentrations may attribute to aryl azo and phthalocyanine paint pigments.

Despite increasing evidence for a major role for sulfation in the metabolism of lower-chlorinated polychlorinated biphenyls in vitro and in vivo, and initial evidence for potential bioactivities of the resulting sulfate ester metabolites, the formation of PCB sulfates in PCB exposed human populations had not been explored. The primary goal of this study was to determine if PCB sulfates, and potentially other conjugated PCB derivatives, are relevant classes of PCB metabolites in the serum of humans with known exposures to PCBs. In order to detect and quantify dichlorinated PCB sulfates in serum samples of 46 PCB-exposed individuals from either rural or urban communities, we developed a high-resolution mass spectrometry-based protocol using 4-PCB 11 sulfate as a model compound. The method also allowed the preliminary analysis of these 46 human serum extracts for the presence of other metabolites, such as glucuronic acid conjugates and hydroxylated PCBs. Sulfate ester metabolites derived from dichlorinated PCBs were detectable and quantifiable in more than 20 % of analyzed serum samples. Moreover, we were able to utilize this method to detect PCB glucuronides and hydroxylated PCBs, albeit at lower frequencies than PCB sulfates. Altogether, our results provide initial evidence for the presence of PCB sulfates in human serum. Considering the inability of previously employed analytical protocols for PCBs to extract these sulfate ester metabolites and the concentrations of these metabolites observed in our current study, our data support the hypothesis that total serum levels of PCB metabolites in exposed individuals may have been underestimated in the past.

Hydroxylated polychlorinated biphenyls (OH-PCBs) have been detected in human specimens and some are suspected as being more toxic than their parent compounds. We compared 58 OH-PCB congeners (in 51 chromatographic peaks) in serum samples from participants in the AESOP Study, a longitudinal cohort study of adolescents and their mothers living in urban and rural areas in the United States. We hypothesized that adolescents would have lower levels of OH-PCBs than their mothers and that serum concentration of OH-PCBs would be stable over a 3-year period. We found statistically significant differences in Σ64 OH-PCBs between age groups in East Chicago (p=0.001) and Columbus Junction (p<0.001), with adolescents having lower concentrations than their mothers. We observed that lower-chlorinated OH-PCBs were rarely detected, suggesting that they are not retained in serum and/or rapidly biotransformed into other forms. Twelve OH-PCBs, including several that are rarely reported (4,4′-diOH-PCB 202, 4′-OH-PCB 208, and 4-OH-PCB 163) were detected in over 60% of participants. Lastly, from repeated measures within subject serum for three OH-PCBs, concentrations of 4-OH-PCB 107 and 4-OH-PCB 187 changed significantly over three years of the study.

Factors contributing to the inter-individual variation in body burden of polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (OH-PCBs) have not been fully elucidated. We examined associations between total serum concentrations of 209 PCBs, 64 OH-PCBs, and frequently detected individual congeners with demographic characteristics (age, gender, ethnicity and community of residence), body mass index (BMI or BMI percentile), and breastfeeding history in children and their mothers from 83 U.S. households. There was a significant positive association between age and concentrations of total PCBs and OH-PCBs in mothers. Non- Hispanics had significantly higher concentrations of total PCBs in mothers and OH-PCBs in children than Hispanics. Concentrations of total PCBs were significantly lower in mothers who had longer breastfeeding duration. Living in the Columbus Junction, Iowa community as compared to East Chicago, Indiana was associated with higher total PCBs in children, probably attributable to higher exposures at school. Lower concentrations of OH-PCBs were significantly associated with a higher BMI percentile in children. Congener-specific associations were observed for 30 PCB and 12 OH-PCB congeners and followed comparable trends. To our knowledge, this is the first study to examine factors contributing to variations in serum concentrations of total 209 PCBs and total OH-PCBs in children, as well as to examine ethnic differences in OH-PCB levels. Results from this study revealed that demographic characteristics, body mass index and breastfeeding history are factors that should be considered for human exposure and risk assessment of PCBs and OH-PCBs.

In this dissertation, concentrations of 209 polychlorinated biphenyl (PCB) congeners and 64 hydroxylated PCB (OH-PCB) congeners were determined in 97 adolescents and 86 mothers living in East Chicago, Indiana and Columbus Junction, Iowa. Sera of the participants were collected between April 2010 and March 2011. PCBs and OH-PCBs in human sera were extracted, separated and quantified using gas chromatography tandem mass spectrometry (GC-MS/MS). A quality control protocol was established to ensure data quality during extraction and analysis processes and to affirm the data were representative, accurate, reproducible and precise. Total PCB concentrations in 164 participants' sera ranged from 0.021-4.683 ng/g fresh weight (f.w.). Associations between the concentration of total 209 PCBs, along with the concentration of an additional 30 individual PCB congeners, and sociodemographic characteristics (age, gender, ethnicity and community of residence), body mass index and breastfeeding history were examined. Total PCB concentrations were significantly higher in older mothers and significantly lower in mothers who experienced longer breastfeeding duration. Columbus Junction adolescents had significantly higher total PCB concentrations than East Chicago adolescents. Associations were also found to be congener-specific. Lower-chlorinated congeners were significantly associated with environmental factors such as community of residence. Host factors such as age, gender, body mass index and breastfeeding history were significantly associated with higherchlorinated PCBs. Non-Aroclor PCBs, PCBs that were not found in Aroclor commercial mixtures, were measured in sera of the participants. Concentration of total non-Aroclor PCBs v among 175 participants ranged from none-detected to 0.288 ng/g f.w. Their concentrations were found to account for an average of 10% (up to 50%) of the overall concentration of total 209 PCBs in human serum. Moreover, an average of 50% of these concentrations may be due to exposure of paint pigments. PCBs 11, 14, 35 and 209 were the major dominating and most frequently detected non-Aroclor PCB congeners in the samples. Adolescents had significantly lower concentrations of total non-Aroclor PCBs than mothers regardless of their community of residence. In addition, total non-Aroclor PCBs were significantly higher in Columbus Junction community. Among the 64 OH-PCB congeners, 58 of them were detected in serum of 159 participants and ranged from 0.017-0.324 ng/g f.w. Total OH-PCB concentrations were significantly lower in adolescents in both communities. Lower-chlorinated OH-PCBs were found to be less frequently detected in serum. Besides that, a few rarely reported OH-PCBs (4, 4'-diOH-PCB 202, 4'-OH-PCB 208, 4-OH-PCB 163, and 3'-OH-PCB 65) were measured an highly detected in the samples. Apart from that, 3'-OH-PCB 65 was discovered for the first time in human serum. Evidence showed possible direct environmental exposure of this congener instead be the result of regular PCB metabolism. Furthermore, concentrat...