On November 8, the EPA announced a public comment period on its systematic review protocol for five per- and polyfluoroalkyl substances (PFAS). PFAS is an umbrella term for thousands of chemicals historically used in manufacturing and consumer goods for their nonstick and flame-retardant properties. A PFAS chemical (typically perfluorooctanesulfonate (PFOS)) is also a major ingredient in firefighting foam used on military bases to contain industrial fires. Some studies have suggested that certain types of the PFAS compounds may be connected with negative human health effects. EPA, the Department of Defense, the Centers for Disease Control and Prevention, and multiple state governments have been evaluating ways to regulate and/or study PFAS chemicals, while the Congress is considering legislation to require additional measures. Most recently, EPA has taken a significant step in establishing a protocol for studying five of these chemicals (PFDA, PFNA, PFHxA, PFHxS and PFBA) to identify and potentially classify hazards associated with them. Available on EPA’s website, the systematic review protocol addresses methods for conducting systematic reviews and dose-response analyses for these five PFAS chemicals. These analyses are an integral step in the hazard classification process. In the protocol, EPA explains that it will focus primarily on oral and inhalational exposure to the five PFAS chemicals and will examine potential developmental, endocrine, hepatic, immune, reproductive and urinary effects, as well as general toxicity and carcinogenicity. EPA’s notice of public comments is the next phase in its PFAS Action Plan, which the agency announced in February 2019. That action plan includes short-and long-term action items designed to respond to concerns expressed by the public about the potential effects from exposure to PFAS chemicals.