What are PFAS? "Forever chemicals" and their health effects, explained

Widely used chemicals called PFAS returned to the headlines as the Environmental Protection Agency announced it's issuing the first-ever national regulation limiting the amount of these substances in drinking water.

PFAS are commonly called "forever chemicals" because it can take thousands of years for them to break down in the environment. The traces are now found nearly everywhere — in air, water, and soil.

PFAS (which stands for per- and polyfluoroalkyl substances) have been in use since the 1940s, often to repel oil and water, and are heat resistant, which makes them popular for a wide variety of products, including cookware, food packaging and paper plates; contact lenses, cosmetics, pharmaceuticals and dental floss; clothing and more. The traces are now found nearly everywhere — in air, water, and soil.