Numerous cases of people developing severe skin reactions days or weeks after having a temporary tattoo have been reported, says Bjšrn Hausen of the Dermatological Centre in Buxtehude, Germany. "It was unbelievably itchy," says one sufferer, who developed a rash after getting a tattoo from a vendor on Venice Beach, California. "And it lasted for a long time. It was the worst thing."
But the problem is not the henna dye itself, an extract of the plant Lawsonia intermis, but the chemical para-phenylene diamine (PPD), Hausen's research has shown. PPD is often added to henna to make the tattoo darker. In some people, it seems henna containing PPD can cause contact dermatitis, in which the skin becomes swollen, red and itchy.
"It is possible that the mark from the tattoo will remain for several months, which is of course socially quite uncomfortable if it concerns parts of the body which are very visible such as the hands or fingers," says Hausen. "But above all, these tattoos can cause a hypersensitivity to PPD." Because the chemical is used in several industrial processes, that means adolescents who are affected will be unable to enter a number of professions, he says.
Hausen showed that PPD is to blame by applying both pure henna and PPD to the skin of people who'd had adverse reactions. Only the PPD produced a strong reaction, he found. Other doctors have got similar results when they carried out allergy tests.
Hausen's findings appear in Deutsches €rzteblatt, the journal of the German Medical Association. The association now plans to launch a Europe-wide information campaign to warn people of the risk.
In Europe and the US, however, most parlours use pure henna, which very rarely causes allergies. The risk is greatest when getting tattoos from street vendors and in third world countries where controls are lax.
Painting henna designs on the body is a long-established practice in India-where it is called mehndi-Morocco and Fiji. A mehndi craze sprang up a couple of years ago after Madonna had her hands elaborately decorated for her pop video Frozen. Overnight, henna body art went from an oriental cultural tradition to a global business and tourist pursuit.
New Scientist issue: 18 AUGUST 2001
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