EPA Science Inventory

Nondefault Uncertainty Factor Values

Citation:

Lipscomb, J. Nondefault Uncertainty Factor Values. Presented at Society of Toxicology, Phoenix, AZ, March 23, 2001 - March 25, 2014.

Description:

A large number of health risk assessments rely on dose response assessments conducted in animal test species, rather than on response infomration derived from humans. this requires extrapolation of findings in animals relative to anticipating a level of response in humans. Under data poor situations, this extrapolation is based on default assumptions, resulting in uncertainty. This presentation is largely based on the WHO International Programme on Chemical Safety's guidance on developing Chemical Specific Adjustment Factors, thus avoiding reliance on default values for uncertainty factors. It guides the evaluation and justification of experimental data primarily applicable to the animal to human exreapolation of toxicity data through a separate consideration of data relevant to tissue distribution (toxicokinetics; TK) and tissue response (toxicodynamics; TD). The principles of dose response are emphasized for each component (TK and TD) of the uncertainty factor for animal to human extrapolation. When the data are judged sufficient for a chemical, quantitative, nondefault values for animal to human extrapolation can be developed. The inclusion of these data reduces some of the uncertainty in health risk assessments.

Purpose/Objective:

This presentation will instruct attendees on advanced methods useful, and accepted for the development of nondefault uncertainty factors where the data warrant. Understanding of this information will further stimulate the appreciation for and development of quantitative information which will reduce uncertainty in health risk assessments through the avoidance of default values for some uncertainty factors.

URLs/Downloads:

LIPSCOMB CSAF SOT AM 02 2014 FINAL.PPT

Record Details:

Record Type: DOCUMENT (PRESENTATION/SLIDE)
Completion Date: 02/13/2014
Record Last Revised: 02/13/2014
Record Created: 02/13/2014
Record Released: 02/13/2014
OMB Category: Other
Record ID: 268762

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL CENTER FOR ENVIRONMENTAL ASSESSMENT