Denmark has proposed banning harmful man-made chemicals known as PFAS from food packaging by 2020, in what would be the first ban of its kind by a nation.

Perfluoroalkyl and polyfluoroalkyl (PFAS), also known as forever chemicals because of their inability to break down in the environment, would be banned from paper and cardboard used with food, according to a press release from the Danish Ministry of Environment and Food on Monday.

The chemicals are used to make products grease- and water-repellent, though studies have shown that they can have adverse health effects on humans and animals.