Human Exposure and Indicator Studies of PCDD/Fs, PCBs, and PCNs in Human Serum

Abstract

Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polychlorinated naphthalenes (PCNs) are environmentally stable and biologically persistent. Due to characteristics of persistence and lipophilicity, human beings are exposed to those pollutants through ingestion, inhalation, and dermal contact. To measure toxic substances in the human body, serum samples were applied in this study.First of all, to assess occupational exposure of PCDD/Fs, I determined the concentrations from municipal solid waste incinerator (MSWI) and industrial waste incinerator (IWI) workers. Higher levels of certain PCDD/F congeners, mainly PCDFs, were detected in the serum of IWI workers, however, no difference was found between MSWI workers and general populations. Therefore, I evaluated those pollutants in non-occupationally exposed subjects including MSWI workers. The mean concentration of total PCBs was about 240 ng/g lipid, penta-, hexa-, and hepta-chlorinated biphenyls contributed more than 80% of the total PCBs detected in human serum. Serum PCB concentrations correlated with age. Total PCBs and dioxin-like PCBs highly correlated with PCB153 (r=0.93) and PCB118 (r=0.98), respectively. Hence, these two congeners could be satisfactory indicators for total PCBs and dioxin-like PCBs in human serum. Unlike PCDD/Fs and PCBs, PCNs have been studied less widely. The mean concentration of PCNs in human serum was about 2000 pg/g lipid. The overall PCN homologues profiles were dominated tetra- and penta-CN homologues, and the most predominant individual congener was hepta-CN-73, which contributed 17% of the total PCN concentration. Enrichment of hepta-CN-73 in human serum samples might be due to contributors from combustion sources. The mean toxic equivalents (TEQs) contributed by PCDDs, PCDFs, PCBs, and PCBs were almost same as 5 pg TEQ/g lipid. The major contributor to PCDD-TEQ was 1,2,3,7,8-PeCDD and the major contribution to PCDF-TEQ was from 2,3,4,7,8-PeCDF. PCB126 and hepta-CN-73 were the predominant congener of PCB-TEQ and PCN-TEQ.The mean concentrations of ∑Cl1-8DD/Fs and seventeen 2,3,7,8-substituted congeners were about 1900 and 400 pg/g lipid, respectively. The profile for PCDDs was dominated by OCDD, while decreasing concentrations with increasing degree of chlorination were seen for PCDFs. MoCDFs contributed more than 60% of ∑Cl1-8DD/Fs and showed highly positive associations with ∑Cl1-8DD/Fs. Thus, 2-MoCDF could be a predictive indicator for ∑Cl1-8DD/Fs (r=0.96), and the combination of 2-MoCDF and OCDD could explain the 96% variation in the serum PCDD/Fs. By measured serum data for ten years, the PCDD/Fs trend was explained

there were no clear declining trends of dioxins in human serum samples. However, there were positive associations between age and dioxins in human serum and showed a slight reduction trends in regard to decreasing the differences of dioxin levels among age groups over time. There was no clearly reduction of dioxins in the human body based on results of this study, but deviations of dioxin levels have declined continuously.