I it's Diane on my mind forever chemicals almost half the tap water in the United States contains P-FES.

These are a class of chemicals that never fully break down, and they're linked to serious health problems.

In April, the Environmental Protection Agency required the removal of these substances from drinking water.

It's a really good step but it's also a drop in the bucket if you will.

ProPublica Sharon Lerner has been reporting on forever chemicals for years.

Her latest piece in the New Yorker is titled,

How Three M Discovered, then concealed

the dangers of forever chemicals. She joined me to talk about the history of Peepest and why they've been so hard to regulate.

Sharon, tell me more about these, quote, forever chemicals. What are they? When were they discovered and what kinds of products are they used in?

Yes, well forever, we're talking about in particular a group of compounds called P-FAS compounds and there are chains of carbon atoms that are linked to fluorine atoms and because the

carbon fluorine bond is one of the strongest in chemistry they are incredibly strong and persistent.

They're basically indestructible.

So it turns out that they also resist moisture and heat, and so they're incredibly useful in industry.

They were first produced on a mass scale in the early 1940s and 3M got into this business because it basically hired some of the former

Manhattan Project chemists who had been using fluorine to create the bomb actually.

And in learning about that chemistry, they were able to devise a way to bond floor into carbon safely, which hadn't been possible on a large scale before.

So those compounds at first were just used for industrial purposes.

And 3M began selling one of the compounds called PFOA to DuPont, which used it in Teflon.

And it began using other compounds in Scotch

Guard. We all know Scotch Guard a product that protects couches and carpets from

stains and other fabrics, right?

And it began using it in food packaging and also in firefighting foam.

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