Based on public health and environmental protection concerns and in response to petitions from the Governor of New Mexico, Public Employees for Environmental Responsibility, and Berkeley School of Law on behalf of five other organizations, which request EPA to take regulatory action on PFAS under RCRA, EPA is evaluating the existing toxicity and health effects data on four PFAS constituents to determine if they should be listed as RCRA Hazardous Constituents. If the existing data for the four PFAS constituents support listing any or all of these constituents as RCRA hazardous constituents, EPA will propose to list the constituents in a Federal Register notice for public comment. The four PFAS chemicals EPA will evaluate are: perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorobutane sulfonic acid (PFBS), and GenX.