Skip to Content


Draft Dioxin Reassessment Documents; Dose-Response Modeling for 2,3,7,8-TCDD, Toxic Equivalency Factors (TEFS) for Dioxin and Related Compounds and Integrated Summary and Risk Characterization for 2,3,7,8-Tetrachlorodibenzo-p

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.


Notice of availability of draft documents for public review and comment and announcement of close of public comment period.


The U.S. Environmental Protection Agency (EPA) is announcing the availability of Science Advisory Board (SAB) review drafts of the Draft Dioxin Reassessment Documents, Chapter 8: Dose-Response Modeling for 2,3,7,8-TCDD, Chapter 9: Toxic Equivalency Factors (TEFs) 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, for public review and comment. The documents were prepared by the EPA's Office of Research and Development (ORD) with the involvement of other federal agencies, in particular the National Institutes of Health's National Institute Start Printed Page 59187of Environmental Health Sciences. The Agency is also announcing the date for the close of the public comment period that began on June 12, 2000.


In a June 12, 2000 Federal Register (65 FR 36898), the Agency announced the beginning of an extended public comment period, on both a previous version of these draft documents as well as those discussed in this Notice. It announced that the comment period began on June 12 and will be concluded two weeks following the SAB peer review meeting in the Fall. All public comments should be submitted by close of business on November 17, 2000. The SAB review meeting is scheduled for November 1 and 2, 2000, and details related to that meeting will be announced in a separate FR notice.

Document Availability

The primary distribution method for the three SAB review drafts of the dose-response modeling chapter (hereafter, Chapter 8), the TEF chapter (hereafter, Chapter 9) and Integrated Summary and Risk Characterization (hereafter, Part III) will be via the Internet on ORD's National Center for Environmental Assessment (NCEA) website. These SAB review drafts, in PDF format, are available at​ncea/​dioxin.htm. These documents can be reviewed and downloaded from the Internet. Background information is also available at the above-mentioned Internet site. This information, provided as background only, consists of other draft final exposure and health sections of the reassessment, specifically Part I: Estimating Exposure to Dioxin-Like Compounds (Volumes 2-4) and Part II: Health Assessment for 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds (Chapters 1-7). In addition, a Compact Disk-Read Only Memory (CD-ROM) containing the three SAB review drafts, the background information, and the draft final Database of Sources of Environmental Releases of Dioxin-Like Compounds in the United States, is available from EPA's National Service Center for Environmental Publications (NSCEP) in Cincinnati, Ohio (telephone: 1-800-490-9198, or 513-489-8190; facsimile 513-489-8695). If you are requesting a copy of the CD-ROM, please provide your name, mailing address, and reference the “Dioxin CD/September 2000” and document number EPA/600/P-00/001Bb-Be. The background documents are available only on CD-ROM and the Internet. A limited number of paper copies of draft Chapter 8, Chapter 9, and Part III will be available from NSCEP. To receive paper copies please provide your name, mailing address, and the document title and number, Part II. Chapter 8: Dose-Response Modeling for 2,3,7,8-TCDD, document number NCEA-I-0835; Part II. Chapter 9: Toxic Equivalency Factors (TEFs) for Dioxin and Related Compounds, document number NCEA-I-0836; and/or Part III. Integrated Summary and Risk Characterization for 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds, document number EPA/600/P-00/001Bg.

Comment Submission

Comments should be in writing and mailed to the Technical Information Staff (8623D), NCEA-W, U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, NW., Ariel Rios Building, Washington, DC 20460, or delivered to the Technical Information Staff at 808 17th Street, N.W., 5th Floor, Washington, DC 20006; telephone: (202) 564-3261; facsimile: (202) 565-0050. One unbound original with pages numbered consecutively, including attachments, and three copies should be submitted. An index is required for any attachments. Electronic comments may be emailed to: Commentors are requested to make clear that their comments pertain to the September 2000 SAB review drafts.

Please note that all technical comments received in response to this notice will be placed in a public record. Commentors should not submit personal information (such as medical data or home address), Confidential Business Information, or information protected by copyright. Due to limited resources, acknowledgments will not be sent.

Start Further Info


For information contact the Technical Information Staff, NCEA-W (8623D), U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, N.W., Washington, DC 20460; telephone: 202-564-3261; facsimile: 202-565-0050; e-mail:

End Further Info End Preamble Start Supplemental Information


In April 1991, EPA announced that it would conduct a scientific reassessment of the health risks of exposure to dioxin and dioxin-like compounds. EPA undertook the 1991 reassessment in light of significant advances in our scientific understanding of mechanisms of dioxin toxicity, significant new studies of dioxin's carcinogenic potential in humans and increased evidence of other adverse health effects.

In September 1994, EPA released the external review drafts of the health effects and exposure documents. In late 1994, EPA took public comment and held numerous public meetings across the country on the drafts, followed by SAB review of the draft dioxin reassessment in May 1995. The SAB's report was received in the Fall of that year. In its report to the Agency, the SAB responded favorably to most portions of the reassessment, but recommended substantive revision of two key sections (Chapter 8 and the Risk Characterization document) and development of an additional document that would focus on TEFs for dioxin and dioxin-like compounds. They also requested that the two redrafted documents and the new TEF chapter be submitted for independent external peer review before being returned to the SAB for re-review. With respect to Chapters 1-7 of the health document and the full exposure reassessment document, the SAB accepted these sections. They suggested that the sections be updated to address public and SAB comments and to incorporate new scientific data. However, the SAB's report stated that substantive further review of these sections by the SAB was not needed.

On July 25 and 26, 2000, an external scientific peer-review meeting was held to review the new Chapter 9 and revised Part III. The third section of the reassessment on which the SAB recommended substantive revision, Chapter 8, underwent public comment and external peer review in March 1997. The July peer review meeting focused on the key science issues including: the characterization of cancer risk, how to extrapolate between animals and humans, non-cancer effects seen close to background exposures, and children's risk. A range of opinions regarding EPA's treatment of these issues in the draft chapters were expressed. Suggestions were made regarding improved presentation of these key science issues.

After the July 25 and 26 external peer review meeting and subsequent receipt of the final meeting report, dated August 24, the documents were revised to address the comments of the scientific peer reviewers and the public comments received prior to September 25, the date the drafts were provided to the SAB review panel. The SAB will conduct its scientific peer review of draft Chapter 8, Chapter 9, and Part III on Wednesday and Thursday, November 1 and 2. The SAB review will be announced in a separate Federal Register notice. Following the SAB meeting, EPA will revise the draft reassessment documents to incorporate appropriate changes that have been indicated by the comments of Federal agencies, the public, and the SAB review panel. SAB approval is Start Printed Page 59188needed to produce a final EPA dioxin reassessment document.

Start Signature

Dated: September 28, 2000.

Henry L. Longest II,

Deputy Assistant Administrator for Management, Office of Research and Development.

End Signature End Supplemental Information

[FR Doc. 00-25473 Filed 10-3-00; 8:45 am]