The U.S. safely disposes of (in landfills) or burns nearly all of our plastic. It’s “out there” in the sense that it’s in 1 of a couple hundred landfills, most of which can be functional for centuries.
Wheelabrator Technologies burns our trash here in NH, boils water, turns a turbine with the steam and produces electricity.
Trex, Azek/Timbertech and several other composite decking manufactures are turning plastic back into a product that is replacing wood decking.