Contents: Risk assessment: historical perspectives; Tissue dosimetry in risk assessment; Modeling: an introduction; Physiologically based pharmacokinetic modeling; Allometry: body size constraints in animal design; Prediction of in vivo parameters of drug metabolism and distribution from in vitro studies; Dose, species, and route extrapolation; Uncertainty in pharmacokinetic models using SIMUSOLV; Interspecies and dose-route extrapolations; Carcinogen DNA-adducts as a measure of biological dose for risk analysis of carcinogenic data; Resources available for simulation in toxicology; Route-to-route extrapolation of dichloromethane exposure using a physiological pharmacokinetic model; Sensitivity analysis in pharmacokinetic modeling; Mutation accumulation: chronic cytotoxicant exposure; Model for ethylene chloride and its application in risk assessment; Mathematical modeling of ozone absorption in the lower respiratory tract; Development of a physiologically based pharmacokinetic model for multiday inhalation of carbon tetrachloride; The delivered/administered dose relationship and its impact on formaldehyde risk estimates; Pharmacokinetic simulation in risk assessment; Hazard assessment: ozone; Role of pharmacokinetic modeling in risk assessment; Development of multispecies, multiroute pharmacokinetic models for methylene chloride and 1,1,1-trichloroethane (methyl chloroform); Methotrexate: pharmacokinetics and assessment of toxicity; Prospective predictions and validations in anticancer therapy; The application of pharmacokinetic data in carcinogenic risk assessment.