That's an interesting bit of info really. Seems like the issue is more related to ridiculous dosage levels and more importantly: method of preparation. I can appreciate the kidney stone threat, but then my body is already prone to them. I found that out several years before starting to use chaga. I grind it into a fine powder and add it to my coffee grounds. Not a lot -maybe half a teaspoon at the most.
Moderation is the key, with anything really.