Per- and polyfluoroalkyl substances (PFAS) are used in a wide array of consumer and industrial products, and have been found in air, soil, water, and biota. Nearly all humans are exposed to these contaminants. Continued exposure above specific levels to certain PFAS may lead to adverse health effects. While an understanding of the occurrence, fate and transport, and exposure is rapidly evolving, there is a substantial need for additional information on these chemicals.