Great comments @jostein! always love your opinions!
the way we get plastic in our food is when the farmer is too lazy to pick up the plastic in the fields, and then cuts the grass, plastic will follow the grass and be fed to the animals we eat, so no, we dont eat plastic directly, nor does our plants as we know of (this might change in future) if as you say the plastic manages to mimic the molecules of other nutrients .

There is hope for us still tho! Fungus, we don't really know what fungus is, but we know that fungus can eat plastic and other petroleum products, we should plant more fungus around.