Chapter 7: Biokinetics

The systemic toxicity of a chemical to an organism depends on: a) the external dose of the chemical; b) the exposure route; c) the absorption, distribution, metabolism and excretion (ADME) of the chemicals, which can be species-specific; and d) the intrinsic properties (biological activity/dynamics) of the chemical. These factors determine the critical concentration of a chemical at its target site(s) of action. Ideally, hazard and risk assessments should be based on the concentration response curve(s) obtained at the target site(s), rather than the dose.response curve obtained for the whole organism.