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Workshop Report on the Application of 2,3,7,8-TCDD Toxicity Equivalence Factors to Fish and Wildlife

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Environmental Protection Agency (EPA).


Notice of availability of a final report.


The U.S. Environmental Protection Agency's (EPA) Risk Assessment Forum (RAF) announces the availability of a final report, Workshop Report on the Application of 2,3,7,8-TCDD Toxicity Equivalence Factors to Fish and Wildlife (EPA/630/R-01/002, August 2001). It is the report of a January 20-22, 1998, workshop sponsored by EPA and the U.S. Department of the Interior (DOI). The Eastern Research Group, Inc. (ERG), an EPA contractor, organized, convened, and conducted the workshop on EPA's behalf. Workshop participants concluded that the toxicity equivalence methodology is appropriate for Start Printed Page 1978evaluating risks to fish, birds, and mammals from mixtures of dioxins, furans, and PCBs.


The document will be made available electronically through the Risk Assessment Forum's Web site (​ncea/​raf/​rafpub.htm). A limited number of paper copies will be available from the EPA's National Service Center for Environmental Publications (NSCEP), PO 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.

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Scott Schwenk, Risk Assessment Forum Staff (8601D), U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, NW., Washington DC 20460; telephone: 202-564-6667; facsimile: 202-565-0062; e-mail:

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In January 1998, a planning committee of EPA and the U.S. Department of the Interior (DOI) 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. The 20 invited workshop participants, seven of whom were from other countries, came from academia, industry, public interest groups, and government. In addition, eight EPA and four DOI planning committee members participated. 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.

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.

The final workshop report consists of (1) an overview and set of conclusions prepared by EPA and DOI and (2) a complete set of workshop materials, including case studies discussed at the workshop, workshop proceedings, pre-meeting comments from the invited experts, and written observer comments.

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Dated: December 20, 2001.

George W. Alapas,

Acting Director, National Center for Environmental Assessment.

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[FR Doc. 02-954 Filed 1-14-02; 8:45 am]