Implementing Probabilistic Methods in US EPA Human Health Assessments
Following the 2020 review of U.S. EPA's ORD Staff Handbook for Developing IRIS Assessments, the National Academies of Science, Engineering, and Medicine recommended EPA should make it explicit in the handbook that probabilistic approaches to derive risk-specific doses will be routinely applied where feasible and should also consider when and how to transition fully away from the traditional deterministic approach to adopt risk-specific doses for its IRIS toxicity values. This presentation to the Biological Perturbations to Probabilistic Hazard Assessment Workshop provides an overview of how probabilistic methods are being implemented into ongoing IRIS assessments and highlights opportunities for propagating uncertainty throughout the pharmacokinetic aspects of the risk assessment process. Following an overview of the pharmacokinetic aspects of risk assessment, this presentation highlights four aspects of the pharmacokinetic risk assessment framework where uncertainty and variability is currently being addressed through ongoing research.