## 2 Materials and Methods
### Dixxin Measurements in Whole Blood  
Around twenty milliliters of venous blood were collected by nursing staff at Bien Hoa health center. Whole blood samples were frozen and transferred to Kanazawa Medical University in Japan, and the levels of 17 2,3,7,8-substituted PCDD/Fs (7 congeners of PCDDs and 10 congeners of polychlorinated dibenzofurans; PCDFs) and four non-ortho-polychlorinated biphenyl (PCB) congeners (3,3,4,4-tetra-chlorinated biphenyl [TCB#77]; 3,4,5-tetra-chlorinated biphenyl [TCB#81]; 3,3,4,4,5-penta-chlorinated biphenyl [PeCB#126]; and 3,3,4,4,5,5-hexa-chlorinated biphenyl [HxCB#169]) were measured. Whole blood samples were frozen and dehydrated in an EYELA freeze dryer (FDU-1200; Tokyo-rika Inc., Tokyo, Japan), and fat was extracted using an ASE-200 accelerated solvent extractor (Dionex Corporation, Sunnyvale, CA, USA). Then, 13C-labeled 2,3,7,8-substituted PCDDs/Fs (DF-LCS-A40; Wellington Inc., Ontario, Canada) and 13C-labeled dioxin-like (dl)-PCBs (DLPCB-CL-A20; Kanto Chemical Co., Inc., Tokyo, Japan) were added to samples as internal standards. After chromatography using a multilayered silica gel column to purify samples, a single-layered column of activated carbon was used to separate and collect the PCDD/Fs and non-ortho PCBs fraction. The final extracted solution was concentrated by evaporation, and 17 PCDD/F congeners and 4 non-ortho PCB congeners were quantified using a gas chromatograph (HP-6980; Hewlett-Packard, Palo Alto, CA, USA) equipped with a high-resolution mass spectrometer (MStation-JMS700; JEOL, Tokyo, Japan). The limit of detection (LOD) for each congener of PCDDs/Fs/ non-ortho PCBs with numbers of samples lower than LODs were shown in Table 1. For quantification of each congener, measurement values were used if they were higher than LODs, but, if not (below LODs), halves of the LODs were used as a quantification values. \begin{table}
\begin{tabular}{r c c c c c c c} \hline \multicolumn{1}{c}{**Dioxin Congeners**} & \multicolumn{4}{c}{**Below LOD**} \\ \multicolumn{1}{c}{**PCDD Congeners (pg/g Lipid)**} & \multicolumn{1}{c}{**LOD (ppt)**} & \multicolumn{1}{c}{**No.**} & \multicolumn{1}{c}{**\%**} & \multicolumn{1}{c}{**\%**} & \multicolumn{1}{c}{**GM**} & \multicolumn{1}{c}{**GSD**} & \multicolumn{1}{c}{**Min**} & \multicolumn{1}{c}{**Max**} \\ \hline
2,3,7,8-TCDD & 0.03 & 2 & 6.3 & 6.4 & 2.1 & 1.5 & 56.2 \\
1,2,3,7,8-PeCDD & 0.03 & 0 & 0 & 10.6 & 1.5 & 4.4 & 22.4 \\
1,2,3,4,7,8-HxCDD & 0.03 & 2 & 6.3 & 6.1 & 1.4 & 3.0 & 11.7 \\
1,2,3,6,7,8-HxCDD & 0.02 & 0 & 0 & 13.3 & 1.5 & 5.5 & 37.2 \\
1,2,3,7,8,9-HxCDD & 0.03 & 0 & 0 & 7.2 & 1.6 & 3.1 & 31.6 \\
1,2,3,4,6,7,8-HpCDD & 0.04 & 0 & 0 & 36.2 & 1.8 & 12.0 & 295 \\ OctaCDD & 0.04 & 0 & 0 & 1027 & 1.6 & 490 & 2570 \\ \hline \multicolumn{1}{c}{PCDF congeners (pg/g lipid)} & & & & & & & \\ \hline
2,3,7,8-TCDF & 0.02 & 2 & 6.3 & 4.4 & 1.6 & 1.6 & 8.3 \\
1,2,3,7,8-PeCDF & 0.03 & 7 & 21.9 & 4.5 & 1.7 & 1.3 & 10.2 \\
2,3,4,7,8-PeCDF & 0.04 & 0 & 0 & 13.6 & 1.3 & 6.6 & 21.9 \\
1,2,3,4,7,8-HxCDF & 0.02 & 0 & 0 & 14.9 & 1.4 & 7.2 & 30.2 \\
1,2,3,6,7,8-HxCDF & 0.02 & 0 & 0 & 10.8 & 1.5 & 2.9 & 19.1 \\
1,2,3,7,8,9-HxCDF & 0.02 & 13 & 40.6 & 3.8 & 2.0 & 0.9 & 67.6 \\
2,3,4,6,7,8-HxCDF & 0.02 & 1 & 3.1 & 3.8 & 1.6 & 1.3 & 9.8 \\
1,2,3,4,6,7,8-HpCDF & 0.02 & 0 & 0 & 13.6 & 1.6 & 5.2 & 50.1 \\
1,2,3,4,7,8,9-HpCDF & 0.04 & 10 & 31.3 & 4.8 & 1.8 & 1.1 & 15.1 \\ OctaCDF & 0.07 & 15 & 46.9 & 10.0 & 1.7 & 2.2 & 21.4 \\ \hline \end{tabular}
\end{table} 
Table 1: Dioxin and non-ortho-PCB levels in blood (\(n=32\)). The TEQ values of PCDDs, PCDFs, and non-ortho PCBs in each sample were calculated by multiplying each congener concentration by its TEQ factor referenced from the World Health Organization 2005 TEQ factors list [14].