Yes it is real, and over the 80 years it's been made of different stuff.
Today it is mostly organic, taken from plants that produce a irritant effect. Today it tends to be safe and mildly effective, though if you bump into a person with a specific allergy or sensitivity you can often get far more than bargained for.
in the now lost past the stuff was made up of all sorts of things chemical and otherwise which could be quite damaging. Fiberglass was one of these older items used, and being basically tiny shards of glass is not a real winner for play time, and if my memory serves the government stepped on its use in the early 80's for safety concerns. Rightly so.
Basically modern powders work on the 'cause a mild allergic reaction' model of things with biological materials being the active ingredient, and thus your milage my very greatly with any individual they are used upon, as people have different sensitivities to different things, and you can't really know until tried.
Myriads
