Prevalence of low chlorinated dibenzo-p-dioxin/dibenzofurans in human serum

Mono- to tri-chlorinated dibenzo-p-dioxin/dibenzofurans (DD/Fs) have not been studied as extensively as the 17 toxic 2,3,7,8-substituted congeners. In this study for the first time, mono- to octa-chlorinated DD/Fs were analyzed for seventy one human serum samples collected from incinerator workers as well as residents living near and far from the facility. The mean concentrations of ∑Cl(1-8)DD/Fs and 17-toxic congeners were 1890 and 398 pg g(-1) lipid (11.9 TEQ pg g(-1) lipid), respectively. 2,3,4,7,8-PeCDF, 1,2,3,7,8-PeCDD, and 1,2,3,6,7,8-HxCDD were predominant congeners that accounted for more than 78% of the TEQ concentrations. The profile for polychlorinated dibenzo-p-dioxins (PCDDs) was dominated by the most chlorinated congener, OCDD (>58%), while decreasing concentrations with increasing degree of chlorination were seen for polychlorinated dibenzofurans (PCDFs); MoCDFs (>83%) and DiCDFs (>6%). ∑Cl(1-3)DD/Fs accounted for 77% of the serum concentrations of ∑Cl(1-8)DD/Fs. These findings confirm that human beings are exposed to a large amount of ∑Cl(1-3)DD/Fs. Moreover, MoCDFs contributed more than 60% of the ∑Cl(1-8)DD/Fs and was highly correlated with ∑Cl(1-8)DD/Fs. Thus, 2-MoCDF could be a predictive indicator for ∑Cl(1-8)DD/Fs (r(s)=0.96), and the combination of 2-MoCDF and OCDD could explain the 95.9% variation in the serum of ∑Cl(1-8)DD/Fs. These results suggest that low chlorinated DD/Fs should be studied extensively until these low chlorinated congeners will have been elucidated for their toxicities.