I'm William Brangham and this is Horizons.

What do nonstick pans, firefighting foam,

and many of our couches, carpets, and cosmetics have in common,

they're all made with PFAS, the so-called Forever Chemicals.

They've helped spur innovation, but they're also insidious to human health.

How did we get here and how can we protect ourselves?

Coming up next.

Welcome to Horizons from PBS News. You may have heard of PFAS. These are the so-called

forever chemicals. They're called that because they're incredibly durable, resilient, synthetic

chemicals that have helped transform modern industry. Teflon is a wonderful electrical

insulator and resists a lot of moisture moisture too. PFS have been used in a vast

array of products, everything from pots and pans to computers to dental floss. They've made fabrics

and carpet stainproof. They've kept us dry from rain and snow. And they've helped send satellites and rockets up into orbit.

But PFAS are also harmful to human health, and they have now spread everywhere on Earth.

So for a deep dive into these chemicals and what we can do about them, we are joined by investigative journalist Mariah Blake.

Her powerful new book is called

They Poisoned the World, which tells the history of these chemicals and the destructive impact

they've had on a few small communities in the U.S. And by Laurel Shader. She's the senior scientist

at the Silent Spring Institute in Massachusetts, where she studies the spread

of PFAS chemicals in drinking water and what they do to human health. Thank you both so much

and welcome to Horizons. Laurel, I'd like to start with you. One of the difficulties I have

in reporting on environmental pollutants is there are so many things that people have to focus on.

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