The Environmental Protection Agency (EPA) has released a series of Parametric Probability Distributions to be used in conjunction with the previously released Exposure Factors Handbook. Whereas the Exposure Factors Handbook provides summaries of available statistical data on several factors used in assessing human exposure to toxic chemicals, the Parametric Probability Distributions document summarizes procedures to fit distributions to some of those data. Three factors (tap water intake, population mobility, and inhalation rules) are considered as test cases in the models, and recommendations are made for models that provide the best fit. For students of statistics, these documents could be used as supplemental examples, illustrating methods useful for addressing actual statistical challenges.