Per- and Polyfluoroalkyl Substances (PFAS) are a family of chemicals used widely in products that resist heat, oils, stains and water. Products manufactured with PFAS include: non-stick cookware; fast-food packaging and pizza boxes; stain- and water-repellant fabrics, including clothing and carpets; and other products found under the brand names Scotchgard, Gore-Tex and Teflon. They also were used in fire-fighting foam (a major source of groundwater contamination at airports and military bases).
There are thousands of types of PFAS, but the two most commonly used, studied and regulated are Perfluorooctanoic acid (PFOA) and Perfluorooctane sulfonate (PFOS). The use of PFOA and PFOS in the U.S. was voluntarily phased out in the 2000s, though they are still used in products manufactured in other countries.