PFAS, or per- and polyfluoroalkyl substances, are a large group of man-made chemicals that include over 4,700 types. These substances are primarily known for their ability to resist heat, oil, stains, grease, and water. PFAS are commonly used in a wide range of products, including non-stick cookware, waterproof clothing, and firefighting foams. They are often referred to as “forever chemicals” because they do not break down in the environment and can accumulate over time in the human body and the natural world.