What are PFAS?

Scientist Ecologist Taking a Water Sample in the Forest

PFAS are man-made chemicals that have been used in industry and consumer products worldwide since the 1950s. They have been used in non-stick cookware, water-repellent clothing, stain resistant fabrics and carpets, some cosmetics, some firefighting foams, and products that resist grease, water, and oil. 

The most commonly studied PFAS are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). The next most commonly studied are perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA). PFOA and PFOS have been phased out of production and use in the United States, but other countries may still manufacture and use them. 

During production and use, PFAS can migrate into the soil, water, and air. Most PFAS (including PFOA and PFOS) do not breakdown, so they remain in the environment. Because of their widespread use and their persistence in the environment, PFAS are found in the blood of people and animals all over the world and are present at low levels in a variety of food products and in the environment. Some PFAS can build up in people and animals with repeated exposure over time. 

Many scientific articles have been published about PFAS exposure and health effects. While it is difficult to show that substances directly cause health conditions in humans, scientific studies have shown that exposure to some PFAS in the environment may be linked to harmful health effects in humans and animals. More research is needed to better understand the health effects of PFAS exposure. 

New kinds of PFAS are being developed. Some of these may have properties similar to the existing PFAS, and some may be less persistent in the environment. There are very few scientific studies on new PFAS, so more research is necessary to discover whether they may be a health concern. 

Exposure to PFAS
  • Drinking contaminated municipal water or private well water
  • Eating fish caught from water contaminated by PFAS (PFOS, in particular)
  • Accidentally swallowing contaminated soil or dust
  • Eating food that was packaged in material that contains PFAS
  • Using some consumer products such as non-stick cookware, stain resistant carpeting, and water repellant clothing.
Page last reviewed: June 24, 2020