I have recently found a company offering sheep's wool rigid acoustic panels, (https://havelockwool.com) Havelock Wool Company, and am considering using them vs the the standard fiberglass/rockwool rigid panels for my DIY wall/ceiling absorbers for my new listening room.
The wool would seem to be safer at a casual glance and wool is supposed to be a superior sound absorber I believe. The cost is a little more, but it is not terribly more expensive.
I would be interested in others opinions on this approach.
Michael