<P> A variety of medical problems, though uncommon, can result from tattooing . </P> <P> Medical workers have observed rare but severe medical complications from tattoo pigments in the body, and have noted that people acquiring tattoos rarely assess health risks prior to receiving their tattoos . </P> <P> A recent case report also showed that tattoo pigments migrate into lymph nodes . These can show up on some types of medical scans as tumors . One woman was given a complete hysterectomy only to find out later that the lymph nodes contained tattoo pigment . </P> <P> Both blacklight and glow in the dark inks have been used for tattooing . Glow in the dark ink absorbs and retains light, and then glows in darkened conditions by process of phosphorescence . Blacklight ink does not glow in the dark, but reacts to non-visible UV light, producing a visible glow by fluorescence . The resulting glow of both these inks is highly variable . </P>

What's in tattoo ink that makes it permanent