A stochastic computer simulation methodology for use with continuous dynamic systems is described. The methodology is applied to a pharmacokinetic model of cadmium in humans, and attempts to account for the statistical variability in cadmium exposure through ingestion in quantifying the predicted health effect of cadmium. The methodology consists of four basic steps: formulation of a realistic physiological pharmacokinetic model for humans, derivation of empirical probability distributions for input variables, numerical solution of the model using ordinary differential equation integration methods and random sampling of the input distribution, and, finally, statistical analysis of the output distributions. Several future directions in the development and application of the methodology are described.