In 2000 OpdenKamp Registration & Notification organized a two-day symposium in The Hague, The Netherlands, on `The Practical Applicability of Toxicokinetic Models in the Risk Assessment of Chemicals'. Several speakers from Europe and the United States were invited to present the different aspects. A vast range of areas was discussed in relation to toxicological modeling and risk assessment, such as occupational toxicology and biomonitoring, exposure to organic solvents and crop protection products, dose-response relations in carcinogenicity, regulatory toxicology, estimation of dermal penetration, uptake and disposition of organic chemicals in fish, the possibilities of in vitro methods in hazard and risk assessment, and the extrapolation between animal and human species. Based on their presentations, the speakers prepared comprehensive papers for this symposium book, reflecting the state of the art of modeling and toxicological risk assessment at the beginning of the third millennium.