Options for Development of Parametric Probability Distributions for Exposure Factors

Users of the Exposure Factors Handbook (EPA/600/P-95/002Fa-Fc) expressed the need to fit distributions to the data in the handbook to assist them when applying probabilistic methods to exposure assessments. The purpose of this document is to fulfill this need. The document summarizes a system of procedures to fit distributions to selected data from the Exposure Factors Handbook. Three factors - tap water intake, population mobility, and inhalation rules - are used at test cases in the document. The system used includes components for models, estimation, assessment of fit, and uncertainty. Eight models were tested including: generalized F, generalized gamma, Burr, gamma, lognormal, Weibull, log-logistic, and exponential. The document provides recommendations on the models that provide the best fit.

Citation

U.S. EPA. Options for Development of Parametric Probability Distributions for Exposure Factors. U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Washington Office, Washington, DC, EPA/600/R-00/058, 2000.