ABSTRACT
The distribution of a pollutant chemical and its metabolites from the point of entry to the different organs and tissues of the body is the role of pharmacokinetics. Pharmacokinetic effects occur in physiological time; when viewed in physiological time, species variability in pharmacokinetic variables may disappear. The greatest difference among species in the pharmacokinetic handling of chemical pollutants is due to differences in routes, mechanisms, and rates of metabolism. An extensive review of the application of pharmacokinetics in risk assessment can be found in the recent report of that title by a committee of the National Research Council. The pharmacokineticist's judgment is needed to decide how many regions must be included to model a particular substance. In addition to anatomical and metabolic factors discussed, pharmacokinetic models may include parameters representing physiological, clearance, thermodynamic, and transport processes in the body.
