It's one of the many, many sources of microplastics. Others include: Anything made of plastic, because it deteriorates over time. Tires with synthetic threads

It's one of the many, many sources of microplastics. Others include: Anything made of plastic, because it deteriorates over time. Tires with synthetic threads, as another HN poster mentioned recently. Plastic shoes (most shoes in western world) Glitter and car paint