In regards to the 6 year old and henna burn; most people assume henna is safe as it is a natural product. Unfortuneately, the owness should be on the tatoo artist to reveal all chemicals added to the natural henna mixture. Many artists add [myself included] cajeput oil (found in tiger balm), eucalyptus oil (an oil added in vick's vapour rub), clove oil, tea tree oil and water. Many artists also add lead without offering that information, and it is that addition which causes the lasting effects. Unfortunetly, many artists do not offer the info. of the ingredients in the henna. Sorry to hear about your son's painful experience.