This is what I have Read thus far from Scholarly Articles through Google Scholar search of heavy metal contamination in the soil.
It seems that the most important thing concerning heavy metal contamination, should it be a problem, is the origins of the soil, the origins of the amendments.
The closer to civilization your medium comes from the greater chances of contamination.
They found PCB in penguins in the Antarctic, hard to get away from pollution.
Granted PCB is not a heavy metal, however heavy metals tend to get into the food sources of Bats and sea birds and other living things we get our poo from..
Peace
It seems that the most important thing concerning heavy metal contamination, should it be a problem, is the origins of the soil, the origins of the amendments.
The closer to civilization your medium comes from the greater chances of contamination.
They found PCB in penguins in the Antarctic, hard to get away from pollution.
Granted PCB is not a heavy metal, however heavy metals tend to get into the food sources of Bats and sea birds and other living things we get our poo from..
Peace