Suddenly I Can’t Work Out Why There is So Much Pollution

All we are doing on the Earth is moving bits of the Earth around and doing things to those bits. There are no more bits being added or taken away, and really no more poisonous bits than there were when the Earth formed.
When the Norwegians pump toxic sludge to the seabed, they might be killing the fish there, but they are removing poison from some other part and enabling life to grow there.
Of course, the fish die pretty quickly but life takes time to colonise an area.