Denmark on Monday (Sept. 2) became the first country to completely ban PFAS from food packaging. The class of chemicals, also referred to as “perflourinated” or “flourinated” compounds, commonly coats microwave popcorn bags, baking paper, and take-out containers.

PFAS are often used to make nonstick pans (like Teflon), waterproof clothing (like Goretex), and firefighting foam. Surfaces coated in PFAS become nonstick and greaseproof, which are great qualities for food packaging.

But here’s the problem: PFAS chemicals have been linked to a range of health risks in humans including cancer, immune system disorders, reproductive abnormalities, and problems with fetal development.

PFAS are present in food packaging around the world. At fast-food chains like Chipotle and Sweetgreen, for example, “compostable” fiber containers are turning up in lieu of plastic ones. While single-use plastic continues to be a very bad idea and a scourge on the planet, and replacing it is, at first blush, a good thing, there’s a problem with the new bowls: They’re lined with PFAS.

The bowls are often marketed as compostable, but as awareness of PFAS grows, that feature is becoming a problem. One study of compost from five US states found PFAS levels as much as ten times higher in the soil from facilities that accepted food packaging. This year, composting facilities in Oregon sent a letter to a biodegradable packaging industry group, to announce that they wouldn’t take any more food packaging. The PFAS would contaminate the facilities’ compost, which could no longer be labeled as organic.

Right now, communities globally are confronting the problem of PFAS contaminating their water supplies. In towns near factories that manufactured PFAS, or used PFAS to make their products, local communities are learning they may have been drinking the chemicals for decades. The compounds are also turning up in water supplies near military bases and airports, which used PFAS foam to put out fires.

The myriad health effects of the many types of PFAS are just beginning to be understood, but already exposure to PFAS is estimated to cost Europe 50 billion euros in health costs each year. The compounds were first manufactured in the US by the companies Dupont and 3M, who knew that their product was a problem, as reporting by Sharon Lerner at the Intercept has shown. 3M, for example, knew that PFAS accumulated in people’s blood and were harmful to their health as early as the 1970s. Likewise, 3M has known since 2001 that PFAS were showing up in the US food supply.

In the US, a bill to ban PFAS in food packaging was introduced in the House of Representatives in May.

In a press release announcing the ban, the Danish government noted that “fortunately” there are other ways to make paper grease-proof and water-proof that don’t have the potential to cause cancer and endocrine disorders (in Danish here).

“We congratulate Denmark on leading the way for healthier food and hope this will encourage similar action across the EU, the US and worldwide,” said Arlene Blum, a chemist at the University of California Berkeley and the founder of the Green Science Policy Institute. “Given the potential for harm, we must ask if the convenience of water and grease resistance is worth risking our health.”