I would also like to see some published facts regarding perlite becoming toxic by absorbing minerals. 'Perlite' is really expanded perlite. (Perlite is a rock.) Unlike vermiculite (expanded mica), the air "compartments" are closed, and cannot be compromised. It is only the rough surface of the expanded perlite granules that can hold water or other particles. This why expanded perlite floats so well, and will never every become waterlogged.
