Characterization of toxicokinetics and toxicodynamics with linear systems theory: Application to lead-associated cognitive decline

We present a theoretical approach to analysis of toxicokinetics and toxicok inetics using linear systems theory, in our approach, we define two impulse response functions that characterize the kinetic behavior of an environmen tal agent in the body and the dynamic time-course behavior of its effect on the body. This approach provides a formalism for understanding the relatio n among exposure, dose, and cumulative biologically effective dose and for understanding the implications of an effect time-course on cross-sectional and longitudinal data analyses. We use lead-associated cognitive decline as a specific example where the approach may be applied.