The powder on balloons is zinc stearate, used in many medications, as well as being the base of clown make-up especially white.. Additionally, it is card fanning powder... It won't hurt you... In my day, when balloon animals used to look like animals, the reason for "mouth-blowing" was/is to give control over the several different diameters used in most of the figures.
Slim

My only comment or question rather is not how it's accomplished, but how in the heck do you avoid your ears from popping!!?? Heck- that would make my head seemingly explode...

Matt Tomasko