Toxicokinetics in Risk Assessment discusses the noncancer risk assessment process and its reliance on uncertainty factors in order to facilitate the continued study and refinement of the scientific basis for health risk assessment. This text clearly demonstrates the application of physiologically-based pharmacokinetic (PBPK) modeling in human health risk assessment, as well as methods for data generation, extrapolation, and inclusion of laboratory results for chemical metabolism and computer-based predictions of biochemical constants to address estimates of variability between experimental animals and humans. This guide also includes recent examples of the use of toxicokinetic information to successfully replace default values for uncertainty factors with data-derived factors in risk assessments developed by the US Environmental Protection Agency.