This two-part presentation suggests that human exposure assessment (HEA) is a science as well as an art. Exposure assessors should be more than an epidemiologist or a toxicologist. They should also have a good background in environmental chemistry, human behavior, computer modeling, and more.

HEA is a science because the exposure estimates so generated are supposedly data-based and quantitative in nature. It is also an art in that certain subjective or otherwise value-laden professional judgement is almost always injected into the assumptions, the defaults, and the data used. For example, the assumption that a two-year-old would spend 10 hours resting and the remaining 14 hours actively playing is at best a good guesstimate for round numbers. The inhalation rates assumed for these two time periods also are likely based on the "best available" or "most convenient" data on hand.

HEA is more than this lecturer's own limited experience in U.S. EPA's process of evaluating human exposure to pesticides. As mentioned in Lecture 4, the World Health Organization (WHO, 1983) was among the first to have published reference books like Guidance on Studies in Environmental Epidemiology, which devotes a good deal to exposure measurement. An international workshop on food consumption and chemical exposure assessment also was held, jointly by the Food and Agricultural Organization and WHO, in Geneva on February 10 - 14, 1997. As still another example of global concern, the EUROPOEM database project on occupational exposure was an undertaking funded by the European Commission (see Slide 14).