U.S. EPA is seeking public input on draft toxicity assessments for GenX chemicals and perfluorobutane sulfonic acid (PFBS), members of a larger group of per- and polyfluoroalkyl substances (PFASs). PFASs are man-made chemicals used in a wide range of products because of their ability to repel water, grease, and oil. These draft assessments are part of EPA's efforts to increase the amount of research and information that is publicly available on chemicals in the PFAS family. To develop the draft toxicity assessments, the agency relied on the best available science, including input from independent peer reviewers. The agency also engaged with federal and state partners throughout the development of the draft assessments. EPA published a request for comments in the Federal Register of November 21, 2018, and the Agency will accept public comments on the GenX chemicals and PFBS draft toxicity assessments for a period of 60 days, which ends January 22, 2019. EPA then will consider the public comments, revise the documents, and consider the need for additional review, as appropriate. More information is posted at https://www.epa.gov/pfas/genx-and-pfbs-draft-toxicity-assessments.