The specific polymers are pretty interesting.

PVC - from plumbing? It's hard to imagine other environmental sources. We're not drinking from PVC cups or eating from PVC plates. I personally would have expected to see particulates from food prep surfaces (teflon pans disintegrating during cooking) since ingestion is a likely path into the body.

Polyethylene - perhaps it's polyethylene terephthalate. Basically any soda or water bottle.