Table 5.

Low-dose linear potency β from analysis of Crofton et al., 2005 data, relative potency (β for the given congener divided by β for the most potent congener, TCDD), and TEF (Van den Berg et al., 2006).

Congenera	Structure	Low-dose Linear Potency β (95% confidence limit) (μg/kg/day)−1	Low-dose Linear Potency (β) relative to TCDD	TEFb
PCB 28	2,4,4′-trichlorobiphenyl	1.10 × 10−5 (9.17 × 10−6, 1.29 × 10−5)	2.07 × 10−6	0
PCB 52	2,5,2′,5′-tetrachlorobiphenyl	1.70 × 10−5 (1.57 × 10−5, 1.82 × 10−5)	3.20 × 10−6	0
PCB 77	3,4,3′,4′-tetrachlorobiphenyl	0.000695 (0.000636, 0.000753)	0.000131	0.0001
PCB 101	2,4,5,2′,5′-pentachlorobiphenyl	9.70 × 10−5 (8.25 × 10−5, 0.000111)	1.83 × 10−5	0
PCB 105	2,3,4,3′,4′-pentachlorobiphenyl	0.000919 (0.000786, 0.00105)	0.000173	3 × 10−5
*PCB 118	2,4,5,3′,4′-pentachlorobiphenyl	0.000636 (0.000525, 0.000748)	0.000120	3 × 10−5
*PCB 126	3,4,5,3′,4′-pentachlorobiphenyl	0.488 (0.433, 0.543)	0.0919	0.1
PCB 138	2,3,4,2′,4′,5′-hexachlorobiphenyl	6.83 × 10−5 (6.03 × 10−5, 7.63 × 10−5)	1.29 × 10−5	0
*PCB 153	2,4,5,2′,4′,5′-hexachlorobiphenyl	4.14 × 10−5 (4.01 × 10−5, 4.26 × 10−5)	7.78 × 10−6	0
PCB 156	2,3,4,5,3′,4′-hexachlorobiphenyl	0.000695 (0.000634, 0.000756)	0.000131	3 × 10−5
PCB 169	3,4,5,3′,4′,5′-hexachlorobiphenyl	0.00210 (0.00191, 0.00230)	0.000396	0.03
PCB 180	2,3,4,5,2′,4′,5′-heptachlorobiphenyl	1.97 × 10−5 (1.57 × 10−5, 2.37 × 10−5)	3.70 × 10−6	0
TCDD	2,3,7,8-tetrachlorodibenzo-p-dioxin	5.31 (4.71, 5.91)	1	1
PCDD	1,2,3,7,8-pentachlorodibenzo-p-dioxin	0.640 (0.227, 1.05)	0.120	0.03
TCDF	2,3,7,8-tetrachlorodibenzofuran	0.194 (0.150, 0.237)	0.0365	0.1
1-PCDF	1,2,3,7,8-pentachlorodibenzofuran	0.0506 (0.0446, 0.0566)	0.00952	0.03
4-PCDF	2,3,4,7,8-pentachlorodibenzofuran	0.0177 (0.0138, 0.0216)	0.00332	0.3
OCDF	1,2,3,4,6,7,8,9-octochlorodibenzofuran	0.000168 (−3.33 × 10−5, 0.000370)	3.17 × 10−5	0.0003

^aPCB congeners are in bold, and those in the NTP studies are marked with an asterisk (*).

^bA zero in the TEF column indicates a congener with no assigned TEF.