[Federal Register Volume 71, Number 184 (Friday, September 22, 2006)]
[Pages 55469-55470]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-8053]




Approaches for the Application of Physiologically Based 
Pharmacokinetic (PBPK) Models and Supporting Data in Risk Assessment

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability.


SUMMARY: EPA is announcing the availability of a final report titled, 
``Approaches for the Application of Physiologically Based 
Pharmacokinetic (PBPK) Models and Supporting Data in Risk Assessment'' 
(EPA/600/R-05/043F), prepared by the National Center for Environmental 
Assessment (NCEA) within EPA's Office of Research and Development 

ADDRESSES: The document is available electronically through the NCEA 
Web site at http://www.epa.gov/ncea. A limited number of paper copies 
will be available from the EPAs National Service Center for 
Environmental Publications (NSCEP), P.O. Box 42419, Cincinnati, OH 
45242; telephone: 1-800-490-9198 or 513-489-8190; facsimile: 513-489-
8695. Please provide your name, your mailing address, the title and the 
EPA number of the requested publication.

FOR FURTHER INFORMATION CONTACT: The Technical Information Staff, 
National Center for Environmental Assessment/Washington Office (8623D), 
U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, NW., 
Washington, DC 20460. Telephone: 202-564-3261; fax: 202-565-0050; e-
mail: [email protected].

SUPPLEMENTARY INFORMATION: This final report highlights the benefits of 
using physiologically based pharmacokinetic (PBPK) modeling and it will 
be used as a learning tool for EPA scientists and health risk 
assessors. It describes

[[Page 55470]]

principles of and the kind of data needed for PBPK modeling, and 
discusses some approaches for the evaluation and use of PBPK models in 
the health assessment of environmental agents. PBPK models represent an 
important class of dosimetry models that are useful for predicting 
internal doses to target organs. To predict internal dose level, PBPK 
models use physiological, biochemical, and physicochemical data to 
construct mathematical representations of processes associated with the 
absorption, distribution, metabolism, and elimination of compounds. 
With the appropriate data, these models can be used to extrapolate 
across species and exposure scenarios, and address various sources of 
uncertainty in health assessments.
    This report addresses the following questions: (1) Why do risk 
assessors need PBPK models; (2) How can these models be used in risk 
assessments; and (3) What are the considerations for evaluating whether 
a PBPK model can be used in a given health assessment of an 
environmental agent?
    The report is not intended to be used as Agency guidance on the use 
of PBPK modeling and does not specify when to use a PBPK model in 
health assessments of environmental agents.

    Dated: September 14, 2006.
George W. Alapas,
Acting Director, National Center for Environmental Assessment.
[FR Doc. 06-8053 Filed 9-21-06; 8:45 am]