Many older floor materials contained asbestos as a strengthener. It was used in a similar way that glass fibers are used in Fiberglass but unfortunately we have later found that asbestos can cause serious health problems.
For remodelers there seems to be no field test that we can use to findout if the tile we are removing has Asbestos in it so regulations usualy assume that all flooring that could contain it should be handled in a way as asbestos made products.
Friable …