In this lecture, students will learn the definition, the purpose, and the function of human exposure assessment (HEA). As pointed out repeatedly in earlier lectures (e.g., Lecture 4) of this series, HEA is a key component of the health risk assessment (RA) process, the latter having a very close relationship with toxicology, epidemiology, and public health. Students will also be provided with a series of observations and presumptions intended to support the argument that it is epidemiologists more than toxicologists apparently having a superior role in HEA.

Four hypothetical exposure scenarios will be presented to demonstrate the dynamics as well as the complexity involved in performing HEA. Both direct and indirect measurement methods can be used to assess human exposure. Students will learn about the basic techniques, the advantages, and the limitations of the direct measurement methods in this lecture. The direct measurement methods almost always involve the use of some form of human biological monitoring to measure the internal dose, which in turn is often used to represent the body burden of a toxin present in the human body at a particular time. This (total) body burden is the total amount supposedly accounting for exposures from all routes and sources, including doses accumulated over time and, if any, produced endogenously.