Document ID: EPA-HQ-ORD-2006-0116-0001
Agency: epa
Document Type: Notice
Title: Harmonization in Interspecies Extrapolation: Use of BW\3/4\ as Default Method in Derivation of the Oral RfD
Posted Date: 2006-02-15T13:12:02Z

[Federal Register: February 15, 2006 (Volume 71, Number 31)]
[Notices]               
[Page 7958-7959]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15fe06-63]                         

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ENVIRONMENTAL PROTECTION AGENCY

[FRL-8031-9; EPA-HQ-Docket ID No. ORD-2006-0116]

 
Harmonization in Interspecies Extrapolation: Use of BW\3/4\ as 
Default Method in Derivation of the Oral RfD

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of public comment period.

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SUMMARY: EPA is announcing a 60-day public comment period for the draft 
document titled, ``Harmonization in Interspecies Extrapolation: Use of 
BW\3/4\ as Default Method in Derivation of the Oral RfD'' (EPA/630/R-
06/001), which was prepared by the EPA's Risk Assessment Forum (Forum).
    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. EPA will consider any public comments 
submitted in accordance with this notice when revising the document.

DATES: The 60-day public comment period begins February 15, 2006, and 
ends April 17, 2006. Technical comments should be in writing and must 
be received by EPA by April 17, 2006.

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 at http://cfpub.epa.gov/ncea/raf/index.cfm. A limited number 

of paper copies are available from the Technical Information Staff, 
NCEA-W; telephone: 202-564-3261; facsimile: 202-565-0050. If you are 
requesting a paper copy, please provide your name, your mailing 
address, and the document title, ``Harmonization in Interspecies 
Extrapolation: Use of BW\3/4\ as Default Method in Derivation of the 
Oral RfD.''
    Comments may be submitted electronically, by mail, by facsimile, or 
by hand delivery/courier. Please follow the detailed instructions 
provided in the SUPPLEMENTARY INFORMATION section of this notice.

FOR FURTHER INFORMATION CONTACT: For information on the public comment 
period, contact the Office of Environmental Information Docket; 
telephone: 202-566-1752; facsimile: 202-566-1753; or e-mail: 
ORD.Docket@epa.gov.

    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 (BW\3/4\) 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 purpose of deriving an oral Reference Dose (RfD). Use of 
BW\3/4\ 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.

II. How to Submit Technical Comments to the Docket

    Submit your comments, identified by Docket ID No. EPA-HQ-ORD 2006-
0116, by one of the following methods:
     http://www.regulations.gov: Follow the on-line 

instructions for submitting comments.
     E-mail: ORD.Docket@epa.gov.
     Fax: 202-566-1753.
     Mail: Office of Environmental Information Docket (Mail 
Code: 28221T), U.S. Environmental Protection Agency, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460. The phone number is 202-566-1752; 
facsimile: 202-566-1753.
    If you provide comments in writing, please submit one unbound 
original with pages numbered consecutively, and three copies of the 
comments. For attachments, provide an index, number pages consecutively 
with the comments, and submit an unbound original and three copies.
     Hand delivery/courier: The Office of Environmental 
Information (OEI) Docket is located in the Headquarters EPA Docket 
Center (EPA/DC), EPA West Building, Room B102, 1301 Constitution Ave., 
NW., Washington, DC. The EPA Docket Center Public Reading Room is open 
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal 
holidays. The telephone number for the Public Reading Room is 202-566-
1744, and the telephone number for the OEI Docket is 202-566-1752; 
facsimile: 202-566-1753; or e-mail: ORD.Docket@epa.gov. Such deliveries

[[Page 7959]]

are only accepted during the Docket's normal hours of operation, and 
special arrangements should be made for deliveries of boxed 
information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-ORD-
2006-0116. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
http://www.regulations.gov, including any personal information 

provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through http://www.regulations.gov or e-mail. The http://www.regulations.gov Web site 

is an ``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an e-mail comment directly to EPA without 
going through http://www.regulations.gov, your e-mail address will be 

automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, any form of encryption, and be free of 
any defects or viruses. For additional information about EPA's public 
docket visit the EPA Docket Center home page at http://www.epa.gov/epahome/dockets.htm
.

    Docket: All documents in the docket are listed in the http://www.regulations.gov
 index. Although listed in the index, some 

information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available either electronically 
in http://www.regulations.gov or in hard copy at the Office of 

Environmental Information (OEI) Docket (EPA/DC), EPA West Building, 
Room B102, 1301 Constitution Ave., NW., Washington, DC. The Public 
Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through 
Friday, excluding legal holidays. The telephone number for the Public 
Reading Room is 202-566-1744, and the telephone number for the OEI 
Docket is 202-566-1752; facsimile 202-566-1753.

    Dated: February 7, 2006
Peter W. Preuss,
Director, National Center for Environmental Assessment.
 [FR Doc. E6-2146 Filed 2-14-06; 8:45 am]

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