That is right.
These substances are part and parcel of earth but the problem is that we are releasing them into the environment in new combinations that do not naturally exist .
Take the plastic bag for instance. It will eventually return to its original components but it takes a hundred years. In those hundred years it can kill thousands of animals which consume it, it promotes spreading of malaria when it accumulates rain water where mosquito eggs hatch and it looks revolting when dumped.