The widely-used polymer molecules which the plastics are named of are mostly stable and harmless (actually, too stable, microplastics problems stems from that).

The widely-used polymer molecules which the plastics are named of are mostly stable and harmless (actually, too stable, microplastics problems stems from that). But 1. plastics need other additives to have the required properties and these are sus 2. plastics over their lifespan dissolve/release other substances you don't want to keep in your body.