Polychlorinated biphenyls and their hydroxylated metabolites in human serum from urban and rural cohorts in the United States

• Main Author: Koh, Wen Xin
• Other Authors: Thorne, Peter S.
• Format: Others
• Language: English
• Published: University of Iowa 2015
• Subjects: Toxicology
• Online Access: https://ir.uiowa.edu/etd/5793; https://ir.uiowa.edu/cgi/viewcontent.cgi?article=7302&context=etd

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 socio-demographic 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 higher-chlorinated 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 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, concentrations of 4-OH-PCB 107 and 4-OH-PCB 187 in human serum changed significantly over 3-year evaluations. The research findings of this dissertation indicate the importance of congener-specific PCB analysis to examine their association with different host and environmental factors. Results of these studies further emphasize the importance of assessing potential toxicity of non-Aroclor PCBs and their adverse health effects to the general population. Thus, studies have significant implications for future human risk assessment.