Skip to Content


Notice of Availability for the Framework for Application of the Toxicity Equivalence Methodology for Polychlorinated Dioxins, Furans, and Biphenyls in Ecological Risk Assessment

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble


Environmental Protection Agency (EPA).


Notice of document availability.


The U.S. Environmental Protection Agency (EPA) is announcing the availability of the final “Framework for Application of the Toxicity Equivalence Methodology for Polychlorinated Dioxins, Furans, and Biphenyls in Ecological Risk Assessment” (EPA/100/R-08/004). The purpose of the Framework is to assist EPA scientists in using the toxicity equivalence methodology to assess ecological risks from mixtures of dioxin-like chemicals, i.e., polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs), as well as to inform EPA decision makers, other agencies, and the public about this methodology. This framework provides an introduction to the toxicity equivalence methodology, offers considerations for how and when to apply the methodology, and presents practical examples of its use. The Framework thus serves to enhance the application of the best available science. This document is not intended to serve as guidance on how to conduct a comprehensive risk assessment for dioxin-like chemicals or to act as a regulation or binding policy. EPA's Risk Assessment Forum oversaw the development of this document, incorporating input obtained from an expert workshop, scientists throughout the Agency, stakeholders, and a peer review by twelve experts from a range of scientific disciplines.


The final document is available electronically through the EPA Office of the Science Advisor's Web site at:​osa/​raf/​tefframework/​. 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 301-604-3408; e-mail Please provide your name and mailing addresses and the title and EPA number (as given above) of the requested publication.

Start Further Info


Seema Schappelle, Risk Assessment Forum, Mail Code 8105R, Environmental Protection Agency, 1200 Pennsylvania Avenue, NW.,Washington, DC 20460; telephone number: (202) 564-3372; fax number: (202) 564-2070, E-mail:

End Further Info End Preamble Start Supplemental Information


For more than a decade, EPA and other organizations have estimated the combined risks that mixtures of PCDDs, PCDFs, and PCBs pose to human health using the toxicity equivalence methodology. As both data and experience with the methodology have accumulated, experts have come to the consensus that the toxicity equivalence methodology can strengthen assessments of ecological risks as well. In 1998, EPA and DOI sponsored a workshop that recommended the development of further guidance on application of the toxicity equivalence methodology in ecological risk assessment. This framework has been developed in direct response to that workshop recommendation. EPA consulted with other federal agencies at key points during the document's development. In July 2003, EPA released a draft Framework for a 60-day public comment period. An external peer review was conducted in 2004 by twelve experts from a range of scientific disciplines.

Start Signature

Dated: May 15, 2008.

George M. Gray,

EPA Science Advisor.

End Signature End Supplemental Information

[FR Doc. E8-13484 Filed 6-13-08; 8:45 am]