[cyberax]

Yes. Thin disposable bags are easily degraded mechanically, resulting in lots of microparticles.

For clothes it's even worse, they produce microparticles at all times, especially during laundry.

[concordDance]

Thin plastic bags in the west have a very short lifecycle that goes mostly shop->home->bin->landfill (segregated from water table). There is almost no opportunity for it to actually contaminate the water.