[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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