New EPA Guidelines for Exposure Assessment: Major Changes at the Agency, 1993 Environmental Conference Proceedings

EPA recently published new Guidelines for Exposure Assessment (54 Federal Register (FR) 1O4:22888-22938, May 29, 1992) that establish a standard framework for the Agency’s exposure and risk assessments. These new Guidelines established several new and far reaching policies. These include the requirement of multiple risk descriptors in Agency risk assessments, the use of standardized exposure terminology, and a major revision of the Maximum Exposed Individual (MEI) concept. The new exposure guidelines have significant implications for risk assessments currently performed under Superfund, RCRA and the Clean Water Act. They require the Agency to use more realistic estimates of individual exposure and to consider both population and subpopulation risks. The use of Monte Carlo modeling to characterize ranges and distributions of risks is encouraged and promoted. The Deputy Assistant Administrator of EPA has instructed all offices to carefully follow the Guidelines and to use the newly established risk descriptors in all future risk assessments. This paper presents a review of the key elements of the Guidelines. Finally, a case example of the new policy’s impacts, the assessment of dioxin discharged to surface waters, will be presented.