Fiberglass insulation does a good job of keep buildings warm but, anyone who's ever handled fiber glass insulation with their bare hands knows that it's dangerous. It leaves tiny splinters in your skin which are driven deeper every time you touch something. The fibers are very hard to see let alone remove. They disperse all over the place, in your carpet, on your furniture, on your pets and in your cloths.
Being made of glass and plastic, the fibers do not dissolve in water so they won't wash off you or wash out of fabric. It's clear that fiberglass insulation is a health hazard.