ABSTRACT
The process of risk assessment for developmental toxicants often requires the application of uncertainty factors or extrapolation methods to facilitate the use of animal studies conducted at high-dose levels for deriving acceptable exposure levels for humans (1). Extrapolations of developmental toxicity benchmarks (e.g., NOAEL) from one exposure route to another as well as from animals to humans can only be conducted with the knowledge of appropriate measure of dose. The measure of dose for developmental toxicants ranges from the environmental concentration (potential dose) to the amount delivered to the developing organism (delivered dose) or the amount of putative toxic moiety per unit volume of blood or the target tissue (internal dose).
