A black light is a flourescent light that projects light through UV changing clear plastic or glass. If you make a wax candle and add a burnable chemical of phosphorescent material with the correct color dye and pigment then you get the glow and luminous effect of a black light from a flame with out the use of an electrical black light. You would only need to make all the chemicals in the wick of the candle non-poisonous, but the fish glowing at the bottom of the ocean with phosphorescent qualities are not dangerous so why should this candle?
I think this would be safe... more proof is needed.
Reward: Too have a discussion about this product since the research is pretty scientific.