Safe face painting glitter.

I remembers when I first started face painting two years ago, I read somewhere that to be considered safe face painting glitter, apart from being polyester, the glitter need to be under certain size in mm. Could anybody let me know the number? Is it 0.04 or 0.08mm or something else?. Many Thanks.
www.mdfacepainting.com

.004 is supposed to be safe even for contact lens wearers. Many of the glitters will literally say on the container "Not safe for use near eyes."

Is 0.004 the size of glitter powder? I ordered some a glitter sample and compared it with Snzaroo glitter dust, it was much finer than Snazaroo, but the size is 0.04mm.