(PeCDD) (21%), 1,2,3,6,7,8-hexachlorodiben- zodioxin (HxCDD) (4.3%), 2,3,4,7,8-pen- tachlorodibenzofuran (PeCDF) (20%), and PCB-126 (21%). The range of PCDD-TEQs (3.36–6.34 pg/g fat) was wider than that of PCDF-TEQs (2.15–3.76 pg/g fat). The percentage PCDF- TEQs of the total PCDD/F-TEQs for the ﬁve Hong Kong pools (37–38%) was lower (Mann-Whitney U-test: Z-score = –1.936, p = 0.053) than that of the two mainland pools (44% and 45%) (Figure 1A). A similar differ- ence was observed between recent and longer- residing China immigrants to Hong Kong, with the PCDF-TEQ proportion of 44% of the PCDD/F-TEQs in pool 8 (Hong Kong residents for 2–6 years) compared with 39% in pool 9 (Hong Kong residents for ≥ 7 years). A relatively higher contribution from mono-ortho PCBs of 41.3–49.7% in the total PCB-TEQs was observed in the five Hong Kong pools, compared with 23.4–32.2% in mainland China and China immigrant pools 6, 7, 8, and 9 (Mann-Whitney U-test: Z-score = –2.449, p = 0.014) (Figure 1B). On average, PCDDs, PCDFs, and PCBs contributed, respectively, 39, 25, and 36% of the total TEQs. The PCDD/F-TEQs and P C B - T E Q w e r e m o d e r a t e l y c o r r e l a t e d [Spearman correlation coefficient = 0.61; 95% conﬁdence interval (CI), 0.53–0.87; p = 0.026]. The contribution from PCB-TEQs to the total TEQ was 30–40% in each pool, except for pool 11 (49%) comprising mothers who migrated to Hong Kong from overseas countries (Table 3). Comparison of TEQ levels among pools. The maximum difference in total WHO- TEQs across the 13 pools was 7.7 pg/g fat (Table 3). Most pools from mothers born in Table 3. Mass concentration of PCDD, PCDF, and PCB congeners and TEQ concentrations by pools. Human dioxin levels in Hong Kong Hong Kong had higher TEQs (10.6, 13.7, 15.2, 13.4, 16.7, and 15.0 pg/g fat) compared with those of mothers from mainland China (8.97 and 11.6 pg/g fat). China immigrants with a longer stay in Hong Kong (pool 9) also had a higher TEQ value (13.5 pg/g fat) than did recent immigrants (pool 8, 10.9 pg/g fat). Pools from both Hong Kong and mainland mothers with higher dairy product and seafood intake (pools 5, 7, and 13) had higher TEQ scores (respectively, 16.7, 11.6, and 14.0 pg/g fat) compared with those with similar residen- tial characteristics but lower consumption pat- terns (pools 4, 6, and 12) (respectively, 13.4, 8.97, and 12.0 pg/g fat). However, a lower TEQ was associated with a younger mean age of mothers (Spearman correlation = 0.85; 95% CI, 0.55–0.96; p < 0.0005) (Figure 2). WHO/EURO 2002–2003 dioxin exposure study. The levels of PCDD/F-TEQs among Congener PCDD congeners (pg/g fat) 2,3,7,8-TCDD 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD OCDD Σ PCDD-TEQ (pg/g fat) PCDF congeners (pg/g fat) 2,3,7,8-TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8-PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF OCDF Σ PCDF-TEQ (pg/g fat) Mono-ortho PCB congeners (ng/g fat) PCB-105 PCB-114 PCB-118 PCB-123 PCB-156 PCB-157 PCB-167 PCB-189 Σ Mono-ortho PCB-TEQ (pg/g fat) Non-ortho PCB congeners (pg/g fat) PCB-77 PCB-81 PCB-126 PCB-169 Σ Non-ortho-PCB-TEQ (pg/g fat) WHO-TEQ (pg/g fat) PCDD/F-TEQ PCB-TEQ (% of total WHO-TEQ) Σ TEQ TEF1998 1 1 0.1 0.1 0.1 0.01 0.0001 0.1 0.05 0.5 0.1 0.1 0.1 0.1 0.01 0.01 0.0001 0.0001 0.0005 0.0001 0.0001 0.0005 0.0005 0.00001 0.0001 0.0001 0.0001 0.1 0.01 1 (25) 1.06 2.34 1.75 5.34 1.50 9.32 51.4 4.35 0.73 0.46 4.19 2.26 1.61 0.58 < 0.13 1.97 0.09 0.58 2.67 1.00 0.22 3.60 < 0.02 1.70 0.33 0.65 0.16 1.61 4.12 2.32 18.1 10.8 1.92 7.02 3.53 (33) 10.6 2 (17) 1.29 2.95 1.95 7.17 2.08 11.9 60.0 5.48 0.97 0.70 5.35 2.66 1.96 0.92 < 0.13 1.41 0.06 0.16 3.39 1.23 0.27 4.82 < 0.02 2.04 0.40 0.79 0.16 1.99 5.18 2.82 26.9 13.6 2.83 8.87 4.82 (35) 13.7 3 (17) 1.44 3.31 2.61 7.64 2.18 13.8 77.5 6.14 1.13 0.80 5.78 2.80 2.01 0.90 0.07 1.75 0.07 0.23 3.64 1.33 0.29 5.16 < 0.03 2.34 0.52 0.96 0.20 2.25 5.24 3.37 29.6 15.9 3.12 9.78 5.37 (35) 15.2 4 (32) 1.26 2.93 2.31 7.07 1.93 13.9 76.5 5.46 0.93 0.63 5.12 2.57 1.84 0.81 < 0.11 1.19 0.06 0.17 3.23 1.37 0.27 5.51 < 0.05 2.27 0.41 0.86 0.17 2.20 4.57 2.80 23.8 11.2 2.50 8.69a 4.69 (35) 13.4a 5 (29) 1.49 3.39 2.33 8.44 2.30 13.9 88.7 6.34 1.04 0.74 6.03 2.72 2.14 0.90 < 0.09 1.33 0.07 0.34 3.76 1.51 0.52 6.23 < 0.03 3.69 0.67 1.24 0.25 3.27 2.80 3.15 31.6 15.8 3.32 10.1 6.58 (39) 16.7 6 (21) 0.92 1.88 1.63 2.37 0.94 6.13 38.0 3.36 1.18 0.91 4.17 2.35 1.98 0.84 < 0.10 2.67 0.08 0.69 2.80 0.60 0.11 2.02 < 0.03 0.67 0.15 0.28 0.05 0.74 4.55 3.52 19.8 8.2 2.07 6.17 2.80 (31) 8.97 Pool (n) 7 8 (34) (22) 1.07 2.26 1.77 2.85 1.11 6.47 31.1 3.97 1.17 0.84 4.80 2.34 1.73 0.74 0.10 1.04 0.05 0.16 3.06 0.97 0.14 3.18 < 0.02 0.95 0.22 0.41 0.06 1.09 3.20 3.43 26.9 9.75 2.79 7.03 3.87 (36) 10.9 1.18 2.49 2.18 3.00 1.18 7.66 43.0 4.39 1.41 1.07 5.15 2.69 2.12 1.00 0.11 1.51 0.09 0.23 3.38 0.80 0.12 2.53 < 0.03 0.81 0.18 0.34 0.06 0.90 4.90 4.48 28.4 10.3 2.95 7.76 3.85 (33) 11.6 9 (23) 1.38 2.96 2.13 5.45 1.57 11.5 50.1 5.37 1.12 0.83 5.34 2.57 1.99 0.84 0.07 1.92 0.08 0.55 3.39 1.19 0.19 4.28 < 0.02 1.41 0.32 0.63 0.11 1.53 3.09 3.13 30.7 13.9 3.20 8.76 4.73a (35) 13.5 10 (18) 1.42 3.15 2.43 8.27 2.05 14.2 65.3 6.00 0.94 0.86 5.48 2.58 1.83 0.80 < 0.11 1.27 0.08 0.20 3.42 1.79 0.33 6.58 < 0.02 2.38 0.51 0.96 0.18 2.48 3.89 3.07 29.7 15.3 3.12 9.42 5.59 (37) 15.0 11 (12) 0.88 2.10 1.27 3.34 1.29 6.76 39.7 3.64 1.07 0.77 3.29 1.58 1.27 0.56 0.08 1.27 0.06 0.30 2.15 2.90 0.36 10.04 < 0.02 2.37 0.53 0.93 0.09 2.97 4.89 3.39 24.9 7.56 2.57 5.80 5.51 (49) 11.3 12 (24) 1.12 2.55 1.76 5.02 1.49 10.0 52.5 4.59 0.98 0.77 4.63 2.26 1.77 0.76 < 0.12 1.11 0.06 0.11 2.96 1.18 0.22 4.35 < 0.02 1.94 0.40 0.71 0.18 1.84 3.20 3.32 24.4 13.8 2.58 7.55 4.42 (37) 12.0 13 (42) 1.27 3.07 2.13 6.95 2.08 14.3 75.3 5.61 1.03 0.77 5.13 2.50 1.93 0.83 < 0.10 1.75 0.08 0.27 3.26 1.23 0.24 4.59 < 0.02 2.04 0.43 0.79 0.16 1.95 2.82 3.31 30.6 15.6 3.22 8.87 5.17 (37) 14.0 Abbreviations: HpCDD, heptachlorodibenzodioxin; HpCDF, heptachlorodibenzofuran; OCDD, octachlorodibenzodioxin; OCDF, octachlorodibenzofuran; TCDF, tetrachlorodibenzofuran. “<” denotes the limit of detection for congeners with undetected mass concentrations. aMedian level among the 13 pools. Environmental Health Perspectives • VOLUME 114 | NUMBER 2 | February 2006 Mean (316) 1.23 2.76 2.06 5.69 1.69 11.0 59.5 5.04 1.06 0.78 5.03 2.46 1.89 0.10 0.82 1.56 0.07 0.30 3.21 1.24 0.25 4.59 < 0.02 1.88 0.38 0.73 0.14 1.87 3.91 3.27 26.8 12.7 2.81 8.25 4.67 12.9 205