Coplanar PCBs and the relative contribution of coplanar PCBs, PCDDs, and PCDFs to the total 2,3,7,8-TCDD toxicity equivalents in human serum.
An analysis of the relative contribution of coplanar polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) to the total 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalents (TEQs) in human serum was performed. Blood samples were collected from 46 males employed in a pulp and paper mill and 16 males living in the local community (controls). The samples were analyzed for serum 3,3',4,4'-tetrachlorobiphenyl (32598133) (PCB- 77), 3,3',4,4',5-pentachlorobiphenyl (57465288) (PCB-126), and 3,3',4,4',5,5'-hexachlorobiphenyl (32774166) (PCB-169) and unspecified PCDDs and PCDFs. TEQs were calculated from the data using approaches described by Safe and the World Health Organization (WHO). PCB-126 and PCB-169 were detected in 94 to 98% of all serum samples. PCB-77 was not detected. The mean serum PCB-126 and PCB- 169 concentrations were higher in the pulp and paper mill workers than in the controls, 25 versus 18 nanograms per kilogram (ng/kg) and 36 versus 27ng/kg, respectively. The difference in PCB-126 concentrations between the two groups was statistically significant whereas that of PCB-169 was not. Serum PCB-126 concentrations were significantly, positively correlated with the BMI. Serum PCB-169 concentrations were significantly, positively correlated with age. Neither PCB-126 nor PCB-169 concentrations were significantly associated with alcohol or local fish consumption. Serum PCB-126 concentrations were significantly higher in nonsmokers than smokers, 26 versus 13ng/kg. Age, BMI, and local fish consumption were significant predictors of the TEQ associated with serum PCB-126 and PCB-169 concentrations in all subjects, explaining 32% of the variance in the data. Working at the pulp and paper mill and smoking were not associated with the TEQ. In all subjects, PCDDs accounted for 63% of the TEQ, PCDFs for 21%, and PCB-126 and PCB-169 for 15% when calculated according to the Safe technique. When calculated using the WHO procedure, PCDDs, PCDFs, and PCB-126 and PCB-169 contributed 66, 24, and 10% to the TEQ. The authors conclude that PCB-126 and PCB-169 made a significant contribution to the serum TEQ, but serum PCDD concentrations made the largest contribution.