TEF estimates
| Moderator:Jouni (see all) |
|
|
| Upload data
|
TEF (Toxic equivalency factor) estimates contain estimates for toxic potencies of dioxins and PCBs, scaled to a common metric, where TCDD has the toxicity 1.
Scope
What are the TEF values of different dioxin and PCB congeners?
Definition
Data
9. TOXIC EQUIVALENCY FACTORS (TEF) FOR DIOXIN AND RELATED COMPOUNDS
9.1. INTRODUCTION
Previous risk assessments of dioxin and dioxin-like compounds from around the world have employed the Toxic Equivalency Factor (TEF) methodology. This method is also used throughout EPA’s dioxin reassessment. This chapter has been added to the EPA’s dioxin reassessment effort to address questions raised by the Agency’s Science Advisory Board (SAB) in 1995. In its Report to the Administrator (U.S. EPA, 1995), the Committee said it "supports EPA’s use of Toxic Equivalencies for exposure analysis..." However, the SAB suggested that, as the toxic equivalent (TEQ) approach was a critical component of risk assessment for dioxin and related compounds, the Agency should be explicit in its description of the history and application of the process and go beyond reliance on the Agency’s published reference documents on the subject (U.S. EPA, 1987; 1989; 1991) to discuss issues raised in review and comment on this approach. Significant additional literature is now available on the subject, and this chapter provides the reader with a summary which is up-to-date through 2000. Future research will be needed to address uncertainties inherent in the current approach. The World Health Organization (WHO) has suggested that the TEQ scheme be reevaluated every 5 years and that TEFs and their application to risk assessment be re-analyzed to account for emerging scientific information (van den Berg et al., 1998).
Dependencies
- TEF concept
- Ah receptor ligands
- TEF concept in environmental health assessment
- TEF concept and uncertainty analysis
- Additivity of TEFs
- TEF concept and ecology
- TEF concept and Ah receptor
- Estimating TEF values
Unit
relative unit (compared with TCDD toxicity)
Result
{{#opasnet_base_link:Op_en4172}}
| Isomer groups | Toxicity factor relative to 2,3,7,8-T4 CDD |
|---|---|
| DD | nontoxic |
| M1CDD | 0.0001 |
| D2CDD | 0.001 |
| T3CDD | 0.01 |
| T4CDDb | 0.01 |
| P5CDD | 0.1 |
| H6CDD | 0.1 |
| H7CDD | 0.01 |
| O8CDD | 0.0001 |
| DF | nontoxic |
| M1CDF | 0.0001 |
| D2CDF | 0.0001 |
| T3CDF | 0.01 |
| T4CDF | 0.5 |
| P5CDF | 0.5 |
| H6CDF | 0.1 |
| H7CDF | 0.01 |
| O8CDF | 0.0001 |
a OME, 1984. b Excluding 2,3,7,8-T4CDD.
| Congener | EPA/87 a | NATO/89 b | WHO/94 c | WHO/98 d | WHO/2005 e |
|---|---|---|---|---|---|
| PCDDs | |||||
| 2,3,7,8-TCDD | 1 | 1 | 1 | 1 | |
| 1,2,3,7,8-PeCDD | 0.5 | 0.5 | 1 | 1 | |
| 1,2,3,4,7,8-HxCDD | 0.04 | 0.1 | 0.1 | 0.1 | |
| 1,2,3,7,8,9-HxCDD | 0.04 | 0.1 | 0.1 | 0.1 | |
| 1,2,3,6,7,8-HxCDD | 0.04 | 0.1 | 0.1 | 0.1 | |
| 1,2,3,4,6,7,8-HpCDD | 0.001 | 0.1 | 0.01 | 0.01 | |
| 1,2,3,4,6,7,8,9-OCDD | 0 | 0.001 | 0.0001 | 0.0003 | |
| PCDFs | |||||
| 2,3,7,8-TCDF | 0.1 | 0.1 | 0.1 | 0.1 | |
| 1,2,3,7,8-PeCDF | 0.1 | 0.05 | 0.05 | 0.03 | |
| 2,3,4,7,8-PeCDF | 0.1 | 0.5 | 0.5 | 0.3 | |
| 1,2,3,4,7,8-HxCDF | 0.01 | 0.1 | 0.1 | 0.1 | |
| 1,2,3,7,8,9-HxCDF | 0.01 | 0.1 | 0.1 | 0.1 | |
| 1,2,3,6,7,8-HxCDF | 0.01 | 0.1 | 0.1 | 0.1 | |
| 2,3,4,6,7,8-HxCDF | 0.01 | 0.1 | 0.1 | 0.1 | |
| 1,2,3,4,6,7,8-HpCDF | 0.001 | 0.01 | 0.01 | 0.01 | |
| 1,2,3,4,7,8,9-HpCDF | 0.001 | 0.01 | 0.01 | 0.01 | |
| 1,2,3,4,6,7,8,9-OCDF | 0 | 0.001 | 0.0001 | 0.0003 | |
| PCBs; IUPAC #, Structure | |||||
| 77 3,3',4,4'-TCB | 0.0005 | 0.0001 | 0.0001 | ||
| 81 3,4,4',5-TCB | - | 0.0001 | 0.0003 | ||
| 105 2,3,3',4,4'-PeCB | 0.0001 | 0.0001 | 0.00003 | ||
| 114 2,3,4,4',5-PeCB | 0.0005 | 0.0005 | 0.00003 | ||
| 118 2,3',4,4',5-PeCB | 0.0001 | 0.0001 | 0.00003 | ||
| 123 2',3,4,4',5-PeCB | 0.0001 | 0.0001 | 0.00003 | ||
| 126 3,3',4,4',5-PeCB | 0.1 | 0.1 | 0.1 | ||
| 156 2,3,3',4,4',5-HxCB | 0.0005 | 0.0005 | 0.00003 | ||
| 157 2,3,3',4,4',5'-HxCB | 0.0005 | 0.0005 | 0.00003 | ||
| 167 2,3',4,4',5,5'-HxCB | 0.00001 | 0.00001 | 0.00003 | ||
| 169 3,3',4,4',5,5'-HxCB | 0.01 | 0.01 | 0.03 | ||
| 170 2,2',3,3',4,4',5-HpCB | 0.0001 | - | - | ||
| 180 2,2',3,4,4',5,5'-HpCB | 0.00001 | - | - | ||
| 189 2,3,3',4,4',5,5'-HpCB | 0.0001 | 0.0001 | 0.00003 |
a U.S. EPA, 1987. b NATO/CCMS, 1989. c Alhlborg et al., 1994. d Van den Berg, 1998. e Van den Berg, 2006.
| Chemical | Number of in vivo endpoints | Range of REPs (mean±std) | Number of end points from subchronic studies | Range of REPs (mean±std) | TEF |
|---|---|---|---|---|---|
| 1,2,3,7,8-PCDD | 22 | 0.16-0.9 (0.5±0.22) | 16 | 0.19-0.9 (0.53±0.24) | 1 |
| 2,3,4,7,8-PCDF | 40 | 0.018-4.0 (0.4±0.7) | 20 | 0.018-0.6 (0.20±0.13) | 0.5 |
| 1,2,3,6,7,8-HxCDD | 3 | 0.015-0.16 | 1 | 0.04 | 0.1 |
| PCB 126 | 62 | 0.0024-0.98 (0.20±0.20) | 31 | 0.004-0.18 (0.13±0.13) | 0.1 |
See also
References
- ↑ U.S.EPA (2003): Toxic Equivalency Factors (TEF) for Dioxin and Related Compounds. In: Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds. Part II: Health Assessment for 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and Related Compounds. Chapter 9. NAS Review Draft NCEA-I-0836. December 2003. www.epa.gov/ncea.
DISCLAIMER This document is a draft. It has not been formally released by the U.S. Environmental Protection Agency and should not at this stage be construed to represent Agency policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
For additional references, see Toxic equivalency factor references.