I am planning on indoor growing Shiitake mushrooms on wood pellets normally used for heating.
Is there a concern for toxic contamination through the pellets? After all the wood has been cut or shredded by blades, which might have leaked heavy metals and machine oils to the material.
Is there cause for concern? What substrate do commercial growing operations use? Can I somehow have the end product tested for certain contamination?
This is what the pellets look like:
There are no additives listed on the packaging and it says "environmentally friendly".