Dan's link should be read. It does NOT say that there are no issues with mineral wool - far from it. It just says that there are no issues with one particular type of mineral wool. And it speculates that there could be issues with cotton. But perhaps most importantly, this conclusion:
"Whatever you choose, always wear a mask, gloves, and protective clothing when handling any of these materials raw and you should be fine. All the materials we use should be safe for normal studio applications. Studios/manufacturers that are still concerned about using any of these materials may wish to opt for a tighter weave fabric or a layer of polyester batting or other wrap glued to the insulation underneath. In fact, that might be good advice for anyone, but that's each person's call to make. "
