PAC Database - Detailed Chemical Data

Chemical Identity
Chemical CAS# UN# Health Code Numbers
Hexachlorodibenzo-p-dioxin, 1,2,3,6,7,8- 57653-85-7 2811
12.00
7.01
4.10
3.10
3.02
3.06
3.07
3.11
10.00
5.10
Formula Synonyms
C12H2Cl6O2 1,2,3,6,7,8-HEXACHLORODIBENZO-P-DIOXIN, 1,2,3,6,7,8-HCDD, 1,2,3,6,7,8-HEXACHLORODIBENZODIOXIN, 1,2,3,6,7,8-HEXACHLORODIBENZO[1,4]DIOXIN, 1,2,3,6,7,8-HEXACHLORODIBENZO[B,E][1,4]DIOXIN
Physical Properties
Mol Wt State MP (°C) BP (°C) VP (Hg) VP (°C) SG LEL (ppm)
390.86 S 285 25
PAC Values
PAC Values (Original Units: mg/m3)
PAC-1 PAC-2 PAC-3
0.0013 0.014 0.085
Converted PAC Values (ppm)
PAC-1 PAC-2 PAC-3
0.000081 0.00088 0.0053
Technical Basis
A review of available sources identified that 1,2,3,6,7,8-HexaCDD is classified as a dioxin. Since the late 1980s, the Environmental Protection Agency (EPA) has implemented a Toxicity Equivalency Factor (TEF) to evaluate the acute toxicity of dioxin and DLCs relative to a reference chemical (2,3,7,8-tetrachlorodibenzo-p-dioxin, CASRN: 1746-01-6), which can be applied to scale these chemicals according to the following equation:
〖TEEL〗_(dioxin or DLC)=〖TEEL〗_(2,3,7,8-TCDD)/〖TEF〗_(dioxin or DLC)
The TEF for 1,2,3,6,7,8-HexaCDD is 0.1. Use of this non-standard TEEL derivation requires additional review and approval according to Sections 4.2 and 4.3, recorded in a deviation memo.
TEEL-1 = TEEL-12,3,7,8-TCDD/ TEF
TEEL-2 = TEEL-22,3,7,8-TCDD/ TEF
TEEL-3 = TEEL-32,3,7,8-TCDD/ TEF
This review generated TEEL values consistent with those in Rev. 29A.
References
2,3,7,8-TCDD TEELs, available at https://edms3.energy.gov/pac/search/detail/1140
Agency for Toxic Substances and Disease Registry. 2022. "ATSDR Office of Community Health Hazard Assessment Toxic Equivalents Guidance for Dioxin and Dioxin-like Compounds." Toxic Equivalents Guidance for Dioxin and Dioxin-like Compounds, April 15: 1-28. Accessed July 17, 2023. https://www.atsdr.cdc.gov/pha-guidance/resources/ATSDR-TEQ-Guidance-Dioxin-and-Dioxin-like-Compounds-508.pdf .
U.S. Environmental Protection Agency. 2023. Dioxin and Dioxin-Like Compounds Toxic Equivalency Information. March 11. Accessed 1 12, 2024. https://www.epa.gov/toxics-release-inventory-tri-program/dioxin-and-dioxin-compounds-toxic-equivalency-information.
U.S. Environmental Protection Agency. 2010. "Recommended Toxicity Equivalence Factors (TEFs) for Human Health Risk Assessments of 2,3,7,8-Tetrachlorodibenzo-p-dioxin and Dioxin-Like Compounds." Risk Assessment Forum. Washington, DC. Accessed July 17, 2023. https://rais.ornl.gov/documents/dioxin_tef.pdf
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PAC values marked with a subscript "A" correspond to 60-minute AEGL values.
PAC values marked with a subscript "E" correspond to ERPG values.
PAC values marked by * are >= 10% lower explosive limit (LEL) but < 50% LEL.
PAC values marked by ** are > 50% LEL but < 100% LEL.
PAC values marked by *** are >= LEL.