PARENT SESSION

(05-04) U.S. Perspective on Probabilistic Risk Assessments and Their Use in Risk Management Decisions.

Sunzenauer, Ingrid¹, Fite, Edward¹, Gallagher, Kathryn¹, Odenkirchen, Edward¹, Irene, Stephanie¹, Urban, Douglas¹, Lin, James^*,1, ¹ U.S. Environmental Protection Agency, Office of Pesticide Programs, Washington, D.C.

ABSTRACT- The U.S. Environmental Protection Agency's Office of Pesticide Programs (OPP) began an initiative in 1997 to revise the ecological assessment process for pesticides through the incorporation of probabilistic tools and methods within a multi-level risk assessment scheme. The purpose of this initiative is to provide Agency regulators and the public with higher level assessments and improved risk characterizations which address risk management questions that cannot be addressed by deterministic screening level analyses. The risk management questions posed by Agency regulators focus on the magnitude, probability, and certainty of assessment predictions and whether the effects are seen across different species. Deterministic assessments are conducted at the lowest level and serve as screening assessments. They are based on conservative assumptions and are focused on the field level. Higher level assessments incorporate probabilistic tools and methods and move from the field to regional assessments. They are more complex and provide expanded risk characterizations. OPP has developed preliminary probabilistic models to address these questions when evaluating aquatic and terrestrial impacts from pesticides. These models are being implemented, and the results will be used in regulatory decision-making. To ensure that the assessments address risk management questions and support regulatory decision-making, OPP has established an ongoing dialogue with regulators through a series of workshops and discussions. The purpose of the workshops are (1) to ensure that Agency regulators understand the methods and results of the deterministic and preliminary probabilistic assessments, and (2) to provide a forum for risk assessors to obtain feedback from Agency regulators regarding the use of the probabilistic assessments in making risk management decisions. In response to this dialogue, the preliminary probabilistic assessments are being expanded to address the effectiveness of risk mitigation measures and other risk management considerations.

Key words: risk assessment and management, pesticide risk assessments