EPA R3 received an Explanation of Significant Difference (ESD) that reviewed the human health risk assessment based on updated toxicity values for polycyclic aromatic hydrocarbons (PAHs) for two OUs at the Washington Navy Yard. The updated values allowed for the previous unacceptable risk designation for PAH exposures at EA 19 and the Eastern Extension EA to be updated to no unacceptable risk , allowing for the removal of LUCs at these OUs.