I put it in my garden. I have some wood ash with it, so it helps some with PH levels, but mostly I use it to lighten the soil and help aerate it. (I have a hand fed stove so I do not use much of it, and it has a lot of clinkers).
I was told just yesterday that it would kill my kids as it has lots of heavy metals in it, and plants uptake that and poisons us, but the guy is a total gloom and doom kind of guy and is from North Carolina so he is using bituminous data and not anthracite data. In addition, we us manure here for crop fertilizer and have for a hundred years or more, and that has lots of copper and zinc in it, yet our soil is able to readily absorb those metals with ease. I know that because as farmers, we are required to soil test our fields every 3 years and to account for heavy metal contamination due to the copper and zinc that is added to cow grain. As a sheep farmer I have to REALLY keep an eye on copper levels because copper kills sheep, and not a whole lot of it either. It takes 12 parts per million to kill a sheep, so I must test their feed and manure to see what they are taking in since I use feed from the dairy farm, and graze land fertilized with cow manure from a dairy farm. Testing has shown my sheep have about 4 parts per million of copper within them so they are very healthy in that regard.
This is the part that has not been discussed to my knowledge on here, and that is, what certain plants and veggies uptake for heavy metals is completely dependent upon what trace minerals surrounds it. In our case, we have high manganese in our soil, and while this promotes compaction, the upside is, it allows heavy metals like copper and zinc not to be
absorbed by plants as readily. Other trace minerals do the same thing, which is why we spread a product called algeafiber on our land...seaweed which is used in the making of carotene which is food product. We use it, not so much for the perlite which lightens the soil to prevent compaction; nor for its lime-like properties, but for its ability to put a host of trace minerals into the ground that normal fertilizers that only contain n,p and k do not have.
What am I saying?
Toxicity relates to overall good soil health. If given a plethora of n,p,k and a trace minerals, the plants are going to uptake what it needs to thrive, BUT if all it has is poor soil and is given heavy metals, yeah it will uptake that in higher numbers.
I did not explain all this to that guy that accused me of trying to kill my kids. I just shook my head like I was dumb because I mean what do I know; I am just a dumb sheep farmer whose future rests completely on that mere 18 inches of soil that is located from bedrock to sky, and not a electronics engineer like him.