Those UV face painters at raves and clubs who use acrylics, fabric, or poster paints do so because these are more easily available and a lot cheaper than genuine cosmetics. They also dry onto the skin and flake off rather than simply washing away, which results in greater persistance in hot rave conditions. All UV flourescent paints contain mildly radioactive molecules. These are encased in a plastic molecular shell in the case of theatrical paints, which is why the UV make up we use is so expensive. A rigourous testing procedure is required to confirm that the inevitable occassional failure of this plastic coating occurs for only an acceptably minute proprtion of the molecules.
Always ask any face painters what sort of paints they are using. We use only water-based makeup expressly designed by reputable theatrical cosmetics companies (Grimas, Fardell and Kryolan) for use on human skin. Having painted many hundreads of people we have only encountered one allergic reaction. Flourescent grease paints are also available, but be advised that these do not easily wash out from cloathes.