California may have a law requiring clothing made from fabric that is more than 50 per cent polyester to bear a label warning that the garment sheds plastic microfibers when machine washed. If the bill passes, the sale or offering for sale of clothing without this label would be prohibited as of January 1, 2020. Hats and shoes would be exempt.

According to the bill, garments made from synthetic fibers such as polyester can shed up to 1,900 microfibers per wash. Since these fibers are small enough to get past filters, they end up in waterways and the ocean. A study of fish sold at California fish markets found 25 percent of fish and a third of shellfish contained plastic debris, with the majority of that plastic debris being microfibers.

Microplastics have the potential to poison the food chain, as these tiny beads of plastic have been found in the stomachs of marine life, as well as the supply of drinking water. It’s estimated that the world’s oceans will contain more plastic than fish by 2050.

The California bill is meant to be in line with other efforts in the state aimed at reducing water pollution, including a ban on personal care products containing plastic microbeads.