PFAS (Per- and Polyfluoroalkyl Substances, "Forever Chemicals")

PFAS, short for per- and polyfluoroalkyl substances, are thousands of synthetic chemicals that resist heat, oil, grease, and water. They have been used since the 1940s in nonstick cookware, food packaging, stain-resistant carpet and clothing, waterproof gear, cosmetics, and firefighting foam. Because their carbon-fluorine bonds are so strong, they barely break down, which is why they are called "forever chemicals." They build up in water, soil, and people.

The two most studied are PFOA and PFOS. On April 10, 2024, the EPA finalized the first national drinking water standards for PFAS, setting enforceable limits of 4.0 parts per trillion for PFOA and for PFOS. The rule also set limits for several other PFAS. In May 2025, the EPA announced it would keep the PFOA and PFOS limits but planned to rescind and reconsider the limits for the other PFAS, and to propose extending the compliance deadline for water systems from 2029 to 2031.

PFAS are behind some of the largest environmental litigation in U.S. history. Water utilities, states, and people living near contaminated sites have sued manufacturers over cleanup costs and health effects, and firefighters have sued over foam exposure. Consumer class actions allege that products marketed as safe or natural contained PFAS, including period underwear, cosmetics, food packaging, and beverages. Consumer cases often turn on independent lab testing and whether the amount found matters.

See our pages on PFAS water contamination, PFAS in products, and AFFF firefighting foam, and the AFFF entry.