Document ID: EPA-HQ-ORD-2006-0116-0006
Agency: epa
Document Type: Notice
Title: Harmonization in Interspecies Extrapolation: Use of BW3/4 as Default Method in Derivation of the Oral RfD
Posted Date: 2006-05-23T12:02:21Z

[Federal Register: May 23, 2006 (Volume 71, Number 99)]
[Notices]               
[Page 29623-29624]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr23my06-39]                         

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ENVIRONMENTAL PROTECTION AGENCY

[FRL-8173-5; Docket I.D. No. EPA-HQ-ORD-0116]

 
Harmonization in Interspecies Extrapolation: Use of 
BW3/4 as Default Method in Derivation of the Oral RfD

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of Peer-Review Teleconference with opportunity for 
public comment.

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SUMMARY: EPA is announcing that Versar, Inc., an EPA contractor for 
external scientific peer review, plans to convene an independent panel 
of experts and organize and conduct an external peer review meeting to 
review the draft document titled, ``Harmonization in Interspecies 
Extrapolation: Use of BW3/4 as Default Method in Derivation 
of the Oral RfD'' (EPA/630/R-06/001). The peer review meeting is 
planned to take place by teleconference. On Februrary 15, 2006, EPA 
announced a 60-day public comment period for the draft document (71 FR 
7958). The draft document was prepared by the Agency's Risk Assessment 
Forum.
    The public comment period and the external peer review are separate 
processes that provide opportunities for all interested parties to 
comment on the document. In addition to considering public comments 
submitted in accordance with the February 15, 2006, announcement of a 
public comment period, EPA intends to forward those comments to Versar, 
Inc. for the external peer review panel prior to the teleconference.

[[Page 29624]]

    EPA is releasing this draft document solely for the purpose of pre-
dissemination peer review under applicable information quality 
guidelines. This document has not been formally disseminated by EPA. It 
does not represent and should not be construed to represent any Agency 
policy or determination.
    The public will be given an opportunity to observe and provide oral 
comments at this teleconference by registering with Versar, Inc. (see 
FOR FURTHER INFORMATION CONTACT, below). The draft document and the 
charge questions for EPA's external peer review are available primarily 
via the Internet on the Risk Assessment Forum's home page under the 
External Review Drafts menu at http://cfpub.epa.gov/ncea/raf/index.cfm. 

In preparing a final report, EPA will consider Versar Inc.'s report of 
the comments and recommendations from the external peer review meeting 
and any public comments that EPA receives in accordance with the 
February 15, 2006, notice (71 FR 7958).

DATES: The peer review teleconference will be held on June 14, 2006, 
from 9 a.m. to no later than 5 p.m., with a break for lunch. The 
teleconference may end earlier than 5 p.m. if less time is needed for 
the reviewers to complete their discussion. Time will be provided for 
public observers who wish to make comments on the document.

ADDRESSES: The draft ``Harmonization in Interspecies Extrapolation: Use 
of BW\3/4\ as Default Method in Derivation of the Oral RfD'' is 
available primarily via the Internet on the Risk Assessment Forum's 
home page under the External Review Drafts menu at http://cfpub.epa.gov/
 ncea/ raf/index.cfm. A limited number of paper copies 

are available from the Technical Information Staff, NCEA-W by 
telephone: 202-564-3261 or by facsimile: 202-565-0050. If you are 
requesting a paper copy, please provide your name, mailing address, and 
the document title, ``Harmonization in Interspecies Extrapolation: Use 
of BW3/4 as Default Method in Derivation of the Oral RfD.'' 
Copies are not available from Versar, Inc.

FOR FURTHER INFORMATION CONTACT: Members of the public may call into 
the teleconference as observers, and there will be a limited time for 
comments from the public. In order to participate, you should contact 
Mr. Andrew Oravetz of Versar, Inc. at aoravetz@versar.com or by phone 
at 703-642-6832 to register. You will be asked for your name, 
affiliation, city and state, and contact information. When registering, 
please also indicate whether you would like to make a statement during 
the call. Time for public comments is limited, and reservations will be 
accepted on a first-come, first-served basis. At a time before June 14, 
2006, registrants will be given the call-in information for the peer 
review teleconference.
    For technical information, please contact Resha M. Putzrath, Risk 
Assessment Forum; telephone: 202-564-3229; facsimile: 202-565-0062; or 
e-mail: putzrath.resha@epa.gov.

SUPPLEMENTARY INFORMATION: 

I. Information About the Document

    The Agency endorses a hierarchy of approaches to derive human 
equivalent oral exposures from data from laboratory animals, with the 
preferred approach being physiologically based toxicokinetic modeling. 
Intermediate approaches include using some chemical-specific 
information. In lieu of data to support either of these approaches, 
body weight scaling to the \3/4\ power (BW3/4) would be 
endorsed as a general default procedure to extrapolate toxicologically 
equivalent doses of chronic orally administered agents from laboratory 
animals to humans for the purposes of deriving an oral Reference Dose 
(RfD). Use of BW3/4 in derivation of RfD values would be 
parallel with current Agency use in derivation of cancer oral slope 
factors. Thus, this paper would harmonize the two main Agency oral 
dose-response extrapolation procedures. This generalized default 
procedure is viewed as an informed, species-specific, dosimetric 
adjustment factor (DAF) that addresses predominantly toxicokinetic and 
some toxicodynamic aspects of the interspecies uncertainty factor 
UFA. Use of this procedure would result in derivation of a 
human equivalent exposure, specifically a human equivalent dose (HED) 
that is to be used in derivation of the oral RfD in a manner parallel 
to the human equivalent concentration (HEC) in derivation of an 
inhalation RfC.

    Dated: May 15, 2006.
George Alapas,
Deputy Director, National Center for Environmental Assessment.
[FR Doc. E6-7836 Filed 5-22-06; 8:45 am]

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