The practice of exposure assessment: a state-of-the-art review.

Each of us encounters hundreds of toxic agents everyday, without exposure and subsequent absorption (uptake) however, there is no risk of injury. Thus, exposure assessment is one of the three legs of the stool (along with toxicity assessment and dose-response assessment) upon which the practice of risk assessment rests. The field of exposure assessment has evolved out of at least 3 other disciplines over the past 50 years, including health physics, industrial hygiene, and epidemiology. Exposure assessments are a necessary component to understanding the hazard posed by exposure to naturally (e.g., aflatoxins in foods, radon in air) and nonnaturally occurring toxicants (e.g., benzene in groundwater, MTBE in air, and food additives). This article presents a thorough review of the field, including a discussion of the terminology used in exposure assessment, a description of how to quantitatively estimate dose for the major sources of exposure (food, water, air, and soil), and many of the best sources of information. In addition, techniques for assessing both variability and uncertainty are presented. Lessons learned over the past twenty years are emphasized. Some example calculations are included, nearly 400 references are cited, and a glossary of terms is provided.