I dry lumber for my job, let me tell you never use cut off maples, beach, ash, poplar. In comercial dry kiln operations some companys put a really nasty chemical on those woods when they are dryed. Not every kiln uses it, I do not, but not safe if its there. The oaks and cherrys hickorys should be ok, as far as I know its not on them. If the lumber is dryed at somebodys home it is safe. Smoke wood is really cheep to buy in the bags, use it and be safe.