[Federal Register Volume 62, Number 36 (Monday, February 24, 1997)]
[Notices]
[Pages 8241-8242]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-4618]


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ENVIRONMENTAL PROTECTION AGENCY
[FRL-5693-9]


Peer-Review Workshop for Draft Dose-Response Modeling Chapter for 
the Reassessment of Dioxin

AGENCY: U.S. Environmental Protection Agency.

ACTION: Notice of Peer-Review Workshop for Draft Dose-Response Modeling 
Chapter of EPA's Health Assessment Document for Dioxin.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) has scheduled a 
peer-review workshop to be held on March 5, 1997, from 9:00 a.m. to 
3:00 p.m. to review a revised draft of Chapter 8. Dose-Response 
Modeling, which is part of the Health Assessment Document for 2,3,7,8-
Tetrachlorodibenzo-p-dioxin (TCDD) and Related Compounds. The health 
assessment document is one component of the Agency's reassessment of 
dioxin.
    This revised chapter on dose-response was one of two chapters 
referred back to the EPA for substantial revision after the Science 
Advisory Board (SAB) review in May 1995. The public is invited to 
attend the workshop, but seating will be limited and advance 
reservations are suggested. Because time is limited for review of the 
draft chapter prior to the peer-review workshop, written comments must 
be provided to the Agency for 60 days subsequent to this notice. All 
comments submitted within that time will be considered when the chapter 
is revised for SAB review. At the workshop, a panel of scientific 
experts from outside the Agency will review the draft dose-response 
modeling chapter which, at this stage, is a work in progress and does 
not represent Agency policy. Since the chapter evaluates only part of 
the evidence supporting dioxin's overall toxic potential, no general 
conclusions regarding the potential health effects or classification of 
these compounds will be presented. This broader determination will be 
based on the full weight-of-evidence and will be part of the risk 
characterization component of the reassessment.

DATES: The peer-review workshop to review the draft dose-response 
modeling chapter will be held March 5, 1997. Comments on the draft 
chapter must be submitted in writing and be postmarked by April 25, 
1997.

ADDRESSES: The meeting will be held at The Channel Inn Hotel, 650 Water 
Street, SW, Washington, D.C. 20024. Members of the public wishing to 
register to attend the meeting may phone Ms. Linda Tuxen at 202-260-
5949 between 10:00 a.m. and 6:00 p.m. Eastern Standard Time. During the 
meeting some time will be designated for questions and comments from 
the floor to encourage interactions among authors, peer-panel members, 
and the other meeting attendees.
    Members of the public may also submit written comments and other 
materials relevant to the topic to: Ms. Linda Tuxen, National Center 
for Environmental Assessment (8601), U.S. Environmental Protection 
Agency, 401 M Street, S.W., Washington, DC 20460, Attention: Dioxin 
Reassessment.
    The draft chapter will be available on or about February 24, 1997. 
To obtain a copy of the draft dose-response modeling chapter, 
interested parties should contact the ORD Publications Center, U.S. 
Environmental Protection Agency, 26 W. Martin Luther King Drive, 
Cincinnati, OH 45268; telephone (513) 569-7562; fax (513) 569-7566. 
Please provide your name, mailing address, and the chapter title and 
EPA number as follows: Chapter 8. Dose-Response Modeling, EPA/600/P-92/
001C8.
    The draft chapter also will be provided for inspection at the ORD 
Public Information Shelf, EPA Headquarters Library, 401 M Street, S.W., 
Washington, DC 20460, between the hours of 10:00 a.m. and 4:00 p.m., 
Monday through Friday, except for Federal holidays, and at all of the 
EPA Regional and Laboratory libraries.

FOR FURTHER INFORMATION CONTACT: To register for the workshop: Ms. 
Linda Tuxen, National Center for Environmental Assessment (8601), U.S. 
Environmental Protection Agency, 401 M Street, S.W., Washington, DC 
20460; phone: 202-260-5949; fax: 202-401-2492; e-mail: 
[email protected].
    For copies of the document: ORD Publications Center, CERI-FRN, 
Office of Research and Development, U.S. Environmental Protection 
Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268; telephone 
(513) 569-7562; fax (513) 569-7566.
    For questions on the overall reassessment of dioxin: Dr. William 
Farland, National Center for Environmental Assessment (8601), Office of 
Research and Development, U.S. Environmental Protection Agency, 401 M 
Street, S.W., Washington, DC 20460; telephone (202) 260-7315; fax (202) 
401-2492; e-mail: [email protected].

SUPPLEMENTARY INFORMATION:

History of the Scientific Reassessment of Dioxin

    As part of the SAB's May 1995 review of the draft Health Assessment 
Document for 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and Related 
Compounds, Chapter 8. Dose-Response Relationships, was identified as 
one that may need substantial revision and further review. The SAB 
commented that the chapter should be revised to better integrate human 
and laboratory animal data, consider alternatives to the linear non-
threshold model, and clarify important

[[Page 8242]]

points. The purpose of this peer-review workshop is to review the 
comments provided independently by the reviewers and to receive further 
comment based on their discussion.
    The EPA has undertaken this task in response to emerging scientific 
knowledge of the biological, human health, and environmental effects of 
dioxin. Significant advances have occurred in the scientific 
understanding of mechanisms of dioxin toxicity, of the carcinogenic and 
other adverse health effects of dioxin in people, of the pathways to 
human exposure, and of the toxic effects of dioxin to the environment.
    In 1985 and 1988, the Agency prepared assessments of the human 
health risks from environmental exposures to dioxin. These assessments 
were reviewed by the Agency's SAB. At the time of the 1988 risk 
assessment, there was general agreement within the scientific community 
that there could be a substantial improvement over the existing 
response approach, but there was no consensus as to a more biologically 
defensible methodology. The Agency was asked to explore the development 
of such a method. The current reassessment activities are in part in 
response to this request.
    The EPA is making each phase of the current reassessment of dioxin 
an open and participatory effort. It previously has convened two public 
meetings (on November 15, 1991, and April 28, 1992) to inform the 
public of the Agency's plans and activities, to hear and receive public 
comments and reviews of the proposed plans for the reassessment, and 
receive any current, scientifically relevant information.
    The Agency convened two peer-review workshops to review draft 
documents related to EPA's scientific reassessment of the health 
effects of dioxin. The first workshop was held September 10 and 11, 
1992, to review a draft exposure assessment titled, Estimating 
Exposures to Dioxin-Like Compounds. The second workshop was held 
September 22-25, 1992, to review eight chapters of a draft health 
assessment document. The epidemiology chapter was also reviewed in 
another workshop on September 8-9, 1993. It should be noted that 
outside scientists have been heavily involved in the writing and peer 
review of these draft documents. Drafts of the health and exposure 
documents were made available for public review and comment in the fall 
of 1994, both with a formal public comment period and at a number of 
public meetings that were held around the country. The SAB reviewed the 
documents in May 1995.
    The purpose of the March 1997 peer-review workshop is to review the 
draft of a revised and expanded dose-response modeling chapter. The 
revised chapter evaluates the scientific quality and strength of the 
dose-response modeling in the evaluation of toxic health effects, both 
cancer and noncancer, from exposure to dioxin, with an emphasis on the 
specific congener, 2,3,7,8-TCDD. A critical analysis of all available 
data has been performed. It is hoped that the peer-review workshop will 
provide a thoughtful and critical review of the dose-response portion 
of the dioxin reassessment.

    Dated: February 20, 1997.
William H. Farland,
Director, National Center for Environmental Assessment.
[FR Doc. 97-4618 Filed 2-21-97; 8:45 am]
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