Workshop Report on the Application of 2,3,7,8-TCDD Toxicity Equivalence Factors to Fish and Wildlife
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
Risk Assessment Forum
In January 1998, a planning committee of EPA and the U.S. Department of the Interior sponsored a workshop on the application of 2,3,7,8-TCDD toxicity equivalence factors (TEFs) to fish and wildlife. TEFs are tools for estimating the combined risks from exposure to complex mixtures of polychlorinated dioxins (PCDDs), furans (PCDFs), and biphenyls (PCBs). The primary objective of the workshop was to identify, document, and compare uncertainties in TEF development and their impact in ecological risk assessments. Major conclusions included:
The toxicity equivalence methodology is technically appropriate for evaluating risks to fish, birds, and mammals.
The toxicity equivalence methodology reduces uncertainties and is less likely to underestimate risks than are methods based on a single compound (e.g., 2,3,7,8-TCDD) or a class of compounds (e.g., total PCBs).
The uncertainties associated with using relative potencies (RePs) or TEFs are not thought to be larger than other uncertainties within the risk assessment process, but they should be better quantified.
Use of a procedure for selecting ReP or TEF values, generally related to taxonomic and endpoint relatedness, should be developed for use in risk assessment.
The planning committee concluded that the results of the workshop support the use of the toxicity equivalence methodology in ecological risk assessment. The committee also suggested the development of additional tools and data to improve the methodology's implementation.
Contact: Risk Assessment Forum Staff, 202-564-6483, or firstname.lastname@example.org
- Framework for Application of the Toxicity Equivalence Methodology for Polychlorinated Dioxins, Furans and Biphenyls in Ecological Risk Assessment (External Review Draft)
- Workshop Report on the Application of 2,3,7,8-TCDD Toxicity Equivalence Factors to Fish and Wildlife (PDF) (385 pp, 3MB, About PDF)
A limited number of paper copies will be available from EPA's National Service Center for Environmental Publications (NSCEP), P.O. Box 42419, Cincinnati, OH 45242; telephone: 1-800-490-9198 or 513-489-8190; facsimile: 513-489-8695. Please provide your name and mailing address and the title and EPA number of the requested publication.
Note: this report is not EPA's reassessment of the health risks from dioxin. Nor does this report establish any EPA policy or guidance. For more information about the dioxin reassessment, please visit EPA's Dioxin Reassessment pages.
U.S. EPA. Workshop Report on the Application of 2,3,7,8-TCDD Toxicity Equivalence Factors to Fish and Wildlife. U.S. Environmental Protection Agency, Risk Assessment Forum, Washington, DC, EPA/630/R-01/002, 2001.