EPA-Expo-Box (A Toolbox for Exposure Assessors)
Exposure assessment is one of the four major steps in risk assessment; others include hazard identification, dose-response assessment, and risk characterization. Exposure assessment is "the process of estimating or measuring the magnitude, frequency, and duration of exposure to an agent, along with the number and characteristics of the population exposed. Ideally, it describes the sources, routes, pathways, and uncertainty in the assessment" (EPA, 1992 Guidelines for Exposure Assessment and IPCS, 2004 Glossary of Key Exposure Assessment Terminology (122 pp, 951KB, About PDF) developed by the International Programme on Chemical Safety).
Exposure may be estimated using one of three approaches: direct measurement (personal monitoring), indirect estimation (scenario evaluation), and exposure reconstruction (biomonitoring or reverse dosimetry). Tools related to the various exposure assessment approaches are provided in EPA-Expo-Box. Alternatively, exposure assessments may be categorized according to exposure media, exposure routes, assessment tiers or types, lifestages and populations, or chemical classes.