PFAS chemicals seemed like a good idea at first. As Teflon, they made pots easier to clean starting in the 1940s. They made jackets waterproof and carpets stain-resistant. Food wrappers, firefighting foam, even makeup seemed better with perfluoroalkyl and polyfluoroalkyl substances.

Then tests started detecting PFAS in people's blood.

Today, PFAS are pervasive in soil, dust, and drinking water around the world. Studies suggest they're in 98 percent of Americans' bodies, where they've been associated with health problems including thyroid disease, liver damage, and kidney and testicular cancer. There are now over 9,000 types of PFAS. They're often referred to as "forever chemicals" because the same properties that make them so useful also ensure they don't break down in nature.

Scientists are working on methods to capture these synthetic chemicals and destroy them, but it isn't simple.