Dermatologists are warning that the henna tattoos, sold everywhere from beachside stands to carnivals to cruise ships, may contain a harmful chemical known as para-phenylenediamine, or PPD. Used to make the temporary tattoos last longer, PPD has been associated with major skin problems including rashes, blistering and even permanent scarring.
At the American Academy of Dermatology's Summer Academy Meeting 2008 in Chicago, dermatologist Sharon E. Jacob, M.D. of the University of California at San Diego pointed out that henna used for temporary tattoos is made from the lawsonia inermis plant. Temporary coloring of the skin with natural henna is considered harmless and only lasts for a few days. To darken the tattoo (making it more visible and long-lasting) some henna tattoo artists are adding PPD, usually used for black hair dye, into the henna mix.
The FDA prohibits direct application of PPD to the skin because of its known health risks. However, since the tattoo industry is not regulated, people, including children, are still getting black henna tattoos and potentially exposing themselves to serious medical problems. Dr. Jacobs advised that if you do choose to get a henna tattoo, do so only if you can be sure that only vegetable henna is used.