Regulations last checked for updates: Jan 18, 2025

Title 40 - Protection of Environment last revised: Dec 30, 2025
Appendix - Table 3 to Subpart III of Part 62—Toxic Equivalency Factors
Dioxin/furan congener Toxic
equivalency factor
A. 2,3,7,8-tetrachlorinated dibenzo-p-dioxin1
B. 12,3,7,8-pentachlorinated dibenzo-p-dioxin0.5
C. 1,2,3,4,7,8-hexachlorinated dibenzo-p-dioxin0.1
D. 1,2,3,7,8,9-hexachlorinated dibenzo-p-dioxin0.1
E. 12,3,6,7,8-hexachlorinated dibenzo-p-dioxin0.1
F. 1,2,3,4,6,7,8-heptachlorinated dibenzo-p-dioxin0.01
G. 0ctachlorinated dibenzo-p-dioxin0.001
H. 2,3,7,8-tetrachlorinated dibenzofuran0.1
I. 2,3,4,7,8-pentachlorinated dibenzofuran0.5
J. 1,2,3,7,8-pentachlorinated dibenzofuran0.05
K. 1,2,3,4,7,8-hexachlorinated dibenzofuran0.1
L. 1,2,3,6,7,8-hexachlorinated dibenzofuran0.1
M. 1,2,3,7,8,9-hexachlorinated dibenzofuran0.1
N. 2,3,4,6,7,8-hexachlorinated dibenzofuran0.1
O. 1,2,3,4,6,7,8-heptachlorinated dibenzofuran0.01
P. 1,2,3,4,7,8,9-heptachlorinated dibenzofuran0.01
Q. 0ctachlorinated dibenzofuran0.001
authority: 42 U.S.C. 7401
source: 43 FR 51393, Nov. 3, 1978, unless otherwise noted.