Nancy Rios Jafolla has been gainfully employed at the Environmental Protection Agency, Region 3, in Philadelphia since 1990. She is a toxicologist in the Hazardous Site Cleanup Division, Office of Technical and Administrative Support, Technical Support Branch for the Superfund Program. Nancy attended Chestnut Hill College where she received her Bachelor of Science degree in Biology in 1982. In 1989, she received her Master of Science degree in Environmental Science from Drexel University. In addition to Nancy's function as a Toxicologist for the Superfund Program, Nancy also is the Agency Regional Consensus Reviewer for the Integrated Risk Information System (IRIS) Program, Office of Research and Development. Nancy is currently active with the Headquarter Interim Dioxin PRGs Action Development Plan (ADP) Workgroup. Nancy was also an active member of the Probabilistic Risk Assessment (PRA) Workgroup, assisting in the publication of the Risk Assessment Guidance for Superfund, Volume III-Part A, December 2001, and in the development and training of PRA for the Region and the Agency. She has been actively involved with the development, review, beta-testing and training of the ProUCL since its inception.