Per- and polyfluoroalkyl substances (PFAS) are human-made compounds that have been in production since the 1940s and have been widely used in industrial applications, firefighting foam, and consumer products. Many PFAS are highly resistant to heat, oil, and water, making them valued for products such as food packaging, stain- and water-repellant fabrics, and nonstick cookware. Certain firefighting foams designed to suppress fuel fires contain PFAS; and, because they help reduce friction, PFAS are also used in a variety of other industries including aerospace, automotive, building and construction, and electronics.
As a class, PFAS include thousands of different chemicals. Research by the Agency for Toxic Substances and Disease Registry suggests that exposure to high levels of certain PFAS may lead to adverse health effects. Currently, there are over 600 PFAS compounds that the U.S. Environmental Protection Agency (EPA) has approved for sale or import into the United States. The most commonly detected and studied PFAS chemicals are PFOA and PFOS. Though industry in the United States has voluntarily phased out PFOA and PFOS, they are still persistent in the environment.
Due to their widespread use, mobility, and tendency to persist for long periods of time, PFAS can often be detected at low ambient levels in the environment. In places where PFAS have actually contaminated water supplies, such contamination is typically localized and associated with a specific facility, for example, at airports and military bases where firefighting training occurs or an industrial facility where PFAS were produced or used to manufacture other products.