US EPA

Dioxin Reassessment, SAB Review Draft

The U.S. Environmental Protection Agency's (EPA) is progressing toward completion of its comprehensive reassessment of dioxin science entitled, "Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds." This page contains the latest information on the status of the reassessment and includes links to download the most recent draft of documents as they pass through various stages of review.

The next major step in the reassessment process for dioxin was submitting 3 key chapters to EPA's Science Advisory Board (SAB) for review, specifically a revised draft document entitled "Part II, Chapter 8. Dose-Response Modeling for 2,3,7,8-TCDD"; "Part II, Chapter 9. Toxic Equivalency Factors (TEF) for Dioxin and Related Compounds"; and "Part III, Integrated Summary and Risk Characterization for 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds." It is important to note that EPA will not use the conclusions of the draft dioxin reassessment for regulatory purposes until the science peer reviews are completed.

The SAB Dioxin Reassessment Review Subcommittee (DRRS) (of the SAB Executive Committee) subsequently met on November 1 and 2, 2000 to review some specific sections of the Dioxin Reassessment document. The "SAB response to the review and meetings to discuss the dioxin reassessment" are also available.

EPA has prepared four information sheets to provide background information on the reassessment and other EPA dioxin-related activities. The information sheets are listed below with a short description of their purpose and contents, as well as the draft reassessment documents.

1. Dioxin: Summary of the Dioxin Reassessment Science
   
   The Dioxin: Summary of the Dioxin Reassessment Science (Information sheet 1) provides an abbreviated summary of the science in the draft dioxin reassessment. It is meant to provide a less technical discussion of the science than the scientific Highlights described under item (2) below, and is aimed at the general public.
   
   
2. Dioxin: Scientific Highlights from Draft Reassessment
   
   The Dioxin: Scientific Highlights from Draft Reassessment (Information Sheet 2) provides a more detailed and technical discussion of the science issues and exposure and source information included in the comprehensive reassessment. The discussion of mechanisms of action and dose-response is of particular interest. It is meant to be of use to risk assessors in EPA regions, to State and other environmental health professionals, and to readers already familiar with dioxin science.



3. Dioxin Reassessment Process: What is the Status of the Reassessment and How Was the Draft Reassessment Developed?
   
   The Dioxin Reassessment Process: What is the Status of the Reassessment and How Was the Draft Reassessment Developed? (Information sheet 3) provides an updated announcement that on October 29, 2003, the National Academy of Sciences (NAS) was officially requested to review EPA's draft dioxin reassessment. Information Sheet 3 also describes the process that EPA has used in developing the draft reassessment.



4. Dioxin: Continuing EPA Efforts to Reduce the Public's Exposure to Dioxin Risks
   
   The Dioxin: Continuing EPA Efforts to Reduce the Public's Exposure to Dioxin Risks (Information sheet 4) describes the Agency's efforts to develop a Cross-Media Dioxin Strategy for dioxin that will be incorporated into an overall Federal effort by the Interagency Working Group on Dioxin (IWG) to prepare a coordinated dioxin risk management strategy. In addition, the fact sheet contains information on the broad set of ongoing dioxin regulatory and risk management activities that EPA is pursuing through its major program areas. Collectively, these actions address all of the major industrial dioxin sources so far identified in the reassessment.

The U.S. Environmental Protection Agency’s (EPA or Agency) is continuing to work towards completion of its reassessment of dioxin exposure and human health effects entitled, Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds - - the dioxin reassessment. The purpose of this information sheet is to describe the process that EPA has used in developing the reassessment and to inform the public about the remaining steps needed to bring this complex scientific activity to a close.

US EPA. Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (Tcdd) and Related Compounds: Science Advisory Board (External Review Draft) (2000). U.S. Environmental Protection Agency, Washington, DC, EPA/600/P-00/001(ab-ad, be,ag), 2000.