[Federal Register Volume 65, Number 196 (Tuesday, October 10, 2000)]
[Notices]
[Pages 60190-60192]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-25976]
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ENVIRONMENTAL PROTECTION AGENCY
[FRL-6883-8]
Science Advisory Board; Notification of Public Advisory Committee
Meeting
Pursuant to the Federal Advisory Committee Act, Public Law 92-463,
notice is hereby given that a Committee of the US EPA Science Advisory
Board (SAB) will meet on the dates and times noted below. All times
noted are Eastern Standard Time. The meeting is open to the public,
however, seating is limited and available on a first come basis.
Important Notice: Documents that are the subject of SAB reviews are
normally available from the originating EPA office and are not
available from the SAB Office--information concerning availability of
documents from the relevant Program Office is included below.
The Dioxin Reassessment Review Committee (DRRC) of the US EPA
Science Advisory Board (SAB), will meet on November 1 and 2, 2000, at
the Ramada Plaza Hotel Pentagon, 4641 Kenmore Avenue, Alexandria, VA.
The hotel telephone number is (703) 751-4510. The meeting will begin at
8:45 a.m. on November 1 and adjourn no later than 5 p.m. on November 2.
Purpose of the Meeting
In April 1991, EPA announced that it would conduct a scientific
reassessment of the potential health risks of exposure to dioxin and
related compounds. The reassessment led to the publication of a multi-
volume document titled ``Exposure and Human Health Reassessment of
2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds.'' The
draft of this document was published in 1994. In 1995, this draft was
reviewed by EPA's Science Advisory Board (SAB), which issued a report
(EPA-SAB-EC-95-021) with the following major findings: (a) There was no
need for further SAB review of health and exposure sections (Chapters
1-7) as long as EPA updated these sections with any relevant new
information before finalizing them; (b) EPA should develop a new
chapter on toxicity equivalence factors (TEFs) to consolidate the
discussion and scientific information on the use of TEFs for dioxin and
related compounds; (c) the sections addressing Dose Response Modeling
(Chapter 8) and the Risk Characterization document (Chapter 9) required
revision and improvement; and (d) the revised chapters on Dose Response
Modeling and Risk Characterization and the new chapter on TEFs should
undergo external peer review and then be brought back to the SAB for
another review.
EPA subsequently revised the document, and conducted an external
peer review as recommended by the SAB (please see http://www.epa.gov/ncea/pdfs/dioxin/final.pdf for a copy of the peer review). The Agency
has now requested that the SAB review the revised reassessment
document.
Charge to the Committee
The Charge asks the DRRC to respond to specific questions in the
following areas: (a) Cancer effects; (b) background and population
exposures; (c) children's risk; (d) relative risks of breast feeding;
(e) the risk characterization summary statement; and (f) dioxin
sources. The complete set of 21 Charge Questions, sorted by category,
follows:
Body Burdens
(Question 1) Did EPA adequately justify its use of body burden as a
dose metric for inter-species scaling? Should the document present
conclusions based on daily dose?
Use of Margin of Exposure Approach
There are two questions on EPA's proposed use of a margin of
exposure (MOE) approach to evaluate dioxin-related health risks.
(Question 2) Has EPA's choice of the MOE approach to risk
assessment adequately considered that background levels of the dioxins
have dropped dramatically over the past decade, and are continuing to
decline? How might the rationale be improved for EPA's decision not to
calculate an RfD/RfC, and for the recommended MOE approach for
conveying risk information? Is an MOE approach appropriate, as compared
to the traditional RfD/RfC? Should the document present an RfD/RfC?''
(Question 3) The SAB commented that previous dose-response modeling
was too limited to biochemical endpoints (CYPIA1, IA2, * * *). Are the
calculations of a range of ED01 body burden for noncancer
effects in rodents responsive and clearly presented? Please comment on
the weight of evidence interpretation of the body burden data
associated with a 1% response rate for non-cancer effects that is
presented in Chapter 8, Appendix I and Figure 8-1 (where EPA considers
that the data best support a range estimate for ED01 body
burdens between 10 ng/kg to 50 ng/kg).
Mechanisms and Mode of Action
Two questions concern how the Integrated Summary addresses the
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mechanisms and mode of action of dioxin toxicity.
(Question 4) How might the discussion of mode of action of dioxin
and related compounds be improved?
(Question 5) Despite the lack of congener-specific data, does the
discussion in the Integrated Summary and Risk Characterization support
EPA's inference that these effects may occur for all dioxin-like
compounds, based on the concept of toxicity equivalence?
Toxicity Equivalence Factors
There are two questions that pertained specifically to the new TEF
Chapter (i.e., Chapter 9) in the dioxin reassessment.
(Question 6) Is the history, rationale, and support for the TEQ
concept, including its limitations and caveats, laid out by EPA in a
clear and balanced way in Chapter 9? Did EPA clearly describe its
rationale for recommending adoption of the 1998 WHO TEFs?
(Question 7) Does EPA establish clear procedures for using,
calculating, and interpreting toxicity equivalence factors?
Non-Cancer Effects
There are two questions regarding how the Integrated Summary
addresses non-cancer effects.
(Question 8) Have the available human data been adequately
integrated with animal information in evaluating likely effect levels
for the non-cancer endpoints discussed in the reassessment? Has EPA
appropriately defined non-cancer adverse effects and the body burdens
associated with them? Has EPA appropriately reviewed, characterized,
and incorporated the recent epidemiological evidence for non-cancer
risk assessment for human populations?
(Question 9) Do reviewers agree with the characterization of human
developmental, reproductive, immunological, and endocrinological
hazard? What, if any, additional assumptions and uncertainties should
EPA embody in these characterizations to make them more explicit?
Cancer Effects
There are three questions regarding how EPA characterized cancer
effects in the Integrated Summary.
(Question 10) Do you agree with the characterization in this
document that dioxin and related compounds are carcinogenic hazards for
humans? Does the weight-of-the-evidence support EPA's judgement
concerning the listing of environmental dioxins as a likely human
carcinogen?
(Question 11) Does the document clearly present the evolving
approaches to estimating cancer risk (e.g., margin of exposure and the
LED01 as a point of departure), as described in the EPA
``Proposed Guidelines for Carcinogenic Risk Assessment'' (EPA/600/P-92/
003C; April 1996)? Is this approach equally as valid for dioxin-like
compounds? Has EPA appropriately reviewed, characterized, and
incorporated the recent epidemiological evidence for cancer risk
assessment for human populations?
(Question 12) Please comment on the presentation of the range of
upper bound risks for the general population based on this
reassessment. What alternative approaches should be explored to better
characterize quantitative aspects of potential cancer risk? Is the
range that is given sufficient, or should more weight be given to
specific data sources?
Background and Population Exposures
There are three questions pertaining to background and population
exposures to dioxin and related compounds.
(Question 13) Have the estimates of background exposures been
clearly and reasonably characterized?
(Question 14) Has the relationship between estimating exposures
from dietary intake and estimating exposure from body burden been
clearly explained and adequately supported? Has EPA adequately
considered available models for the low-dose exposure-response
relationships (linear, threshold, ``J'' shaped)?
(Question 15) Have important ``special populations'' and age-
specific exposures been identified and appropriately characterized?
Children's Risk
One question addresses the issue of children's risk of dioxin
exposure.
(Question 16) Is the characterization of increased or decreased
childhood sensitivity to possible cancer and non-cancer outcomes
scientifically supported and reasonable? Is the weight of evidence
approach appropriate?
Relative Risks of Breast Feeding
(Question 17) Has EPA adequately characterized how nursing affects
short-term and long-term body burdens of dioxins and related compounds?
Risk Characterization Summary Statement
(Question 18) Does the summary and analysis support the conclusion
that enzyme induction, changes in hormone levels, and indicators of
altered cellular function seen in humans and laboratory animals,
represent effects of unknown clinical significance, but they may be
early indicators of toxic response?
(Question 19) Has the short summary statement in the risk and
hazard characterization on page 107 adequately captured the important
conclusions, and the areas where further evaluation is needed? What
additional points should be made in this short statement?
Sources
(Question 20) Are these sources adequately described and are the
relationships to exposure adequately explained?
General Comments
(Question 21) Please provide any other comments or suggestions
relevant to the two review documents, as interest and time allow.
Availability of Review Materials
The principal review documents (Part III: Integrated Summary and
Risk Characterization for 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD)
and Related Compounds; Chapter 8, Dose-Response Modeling for 2,3,7,8-
Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds; Chapter 9:
Toxicity Equivalence Factors (TEFs) for Dioxin and Related Compounds;
and Exposure and Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-
Dioxin (TCDD) and Related Compounds) were developed by the US EPA's
Office of Research and Development, National Center for Environmental
Assessment (ORD/NCEA) and are available on the Internet at the ORD/NCEA
website (http://www.epa.gov/ncea/dioxin.htm), or by request to Ms.
Linda Tuxen, phone (202) 564-3332, or by email to [email protected].
FOR FURTHER INFORMATION CONTACT: Any member of the public wishing
further information concerning this meeting or wishing to submit brief
oral comments (10 minutes or less) must contact Samuel Rondberg,
Designated Federal Officer, Science Advisory Board (1400A), U.S.
Environmental Protection Agency, 1200 Pennsylvania Avenue, NW,
Washington, DC 20460; telephone (301) 812-2560, FAX (410) 286-2689; or
via e-mail at [email protected]. Requests for oral comments must be in
writing (e-mail, fax or mail) and received by Mr. Rondberg no later
than noon (EDT) on Friday, October 20, 2000. The draft meeting Agenda
will be available approximately three weeks prior to the meeting on the
SAB website (www.epa.gov/sab) or from Ms. Wanda Fields, Management
Assistant, USEPA Science Advisory Board (1400A), U.S.
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Environmental Protection Agency, 1200 Pennsylvania Avenue, NW,
Washington, DC 20460; telephone (202) 564-4539, FAX (202) 501-0582; or
via e-mail at [email protected].
Providing Oral or Written Comments at SAB Meetings
It is the policy of the Science Advisory Board to accept written
public comments of any length, and to accommodate oral public comments
whenever possible. The Science Advisory Board expects that public
statements presented at its meetings will not be repetitive of
previously submitted oral or written statements. Oral Comments: In
general, each individual or group requesting an oral presentation at a
face-to-face meeting will be limited to a total time of ten minutes.
For teleconference meetings, opportunities for oral comment will
usually be limited to no more than three minutes per speaker and no
more than fifteen minutes total. Deadlines for getting on the public
speaker list for a meeting are given above. Speakers should bring at
least 35 copies of their comments and presentation slides for
distribution to the reviewers and public at the meeting. Written
Comments: Although the SAB accepts written comments until the date of
the meeting (unless otherwise stated), written comments should be
received in the SAB Staff Office at least one week prior to the meeting
date so that the comments may be made available to the committee for
their consideration. Comments should be supplied to the appropriate DFO
at the address/contact information noted above in the following
formats: one hard copy with original signature, and one electronic copy
via e-mail (acceptable file formats: WordPerfect, Word, or Rich Text
files (in IBM-PC/Windows 95/98 format). Those providing written
comments and who attend the meeting are also asked to bring 25 copies
of their comments for public distribution.
General Information
Additional information concerning the Science Advisory Board, its
structure, function, and composition, may be found on the SAB Website
(http://www.epa.gov/sab) and in The FY1999 Annual Report of the Staff
Director which is available from the SAB Publications Staff at (202)
564-4533 or via fax at (202) 501-0256. Committee rosters, draft Agendas
and meeting calendars are also located on our website.
Meeting Access
Individuals requiring special accommodation at this meeting,
including wheelchair access to the conference room, should contact Mr.
Rondberg at least five business days prior to the meeting so that
appropriate arrangements can be made.
Dated: September 22, 2000.
Donald G. Barnes,
Staff Director, Science Advisory Board.
[FR Doc. 00-25976 Filed 10-6-00; 8:45 am]
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