KAPALUA, HAWAII — Paraphenylenediamine, a chemical found in permanent hair and fur dyes and temporary henna tattoos, has been chosen as the American Contact Dermatitis Society's 2006 Allergen of the Year.
“All these little kids who become allergic to their henna tattoos will not be able to dye their hair permanently again,” Dr. David E. Cohen said at the Winter Clinical Dermatology Conference, Hawaii, where he announced the selection.
Dr. Cohen, director of allergic, occupational, and environmental dermatology at New York University School of Medicine, said the dubious honor is designed to draw attention to allergens that are very common and/or underrecognized and merit more attention because they are causing significant contact dermatitis.
As the society's presentation on paraphenylenediamine has not yet been published, he gave his views on why physicians need to be more aware of its effects.
Paraphenylenediamine is well known as an allergen that can provoke reactions to permanent hair dyes, according to Dr. Cohen. The heightened sensitivity brought on by its use in temporary henna tattoos is a newer phenomenon.
Distinguishing ceremonial tattoos from the darker temporary products sold in this country, he said henna is safe as used in India and other traditional societies.
“Those [ceremonial tattoos] are pure henna tattoos, but the black henna tattoos are compounded with paraphenylenediamine to get the darker color and to get more endurance,” he explained in an interview at the meeting, which was sponsored by the Center for Bio-Medical Communications Inc.
As a result the commercial tattoos can contain higher concentrations of paraphenylenediamine than the larger quantity used in hair dye, according to Dr. Cohen.
This exposure can in turn lead to a lifelong allergy, he said, reporting that recent research has shown that concentration of the sensitizing agent is more important than the overall dose in triggering sensitization.
“If you introduce higher concentrations of paraphenylenediamine in these small locations, you are going to increase the initial sensitization,” he said.
Practitioners have long been concerned about paraphenylenediamine, he said. And finding an alternative product is difficult when allergic patients want to color their hair, which many do.
He cited a recent British study that found 18% of men and 75% of women had dyed their hair at some point during their lives. The median age of first hair dye was 16 years, with a range of 1–80 years. One in 20 people who dyed their hair had an adverse reaction. Of these, only 15% sought help from a dermatologist (Br. J. Dermatol. 2005;153:132–5).
Typically, packages of permanent dyes include a sensitivity test that purchasers can use at home if they are concerned about an allergic reaction. Dr. Cohen recommended that people be encouraged to try these tests before using a product that contains paraphenylenediamine.
“It is almost as good as doing our patch test,” he said. “They will learn quickly if they are allergic to it.
In addition, Dr. Cohen urged physicians to be familiar with previous Allergens of the Year, of which he noted the following:
▸ 2005: Corticosteroids. Dr. Cohen said screening tests are available for tixocortol, budesonide, and hydrocortisone butyrate.
▸ 2004: Cocamidopropyl betaine. Found in more than 600 personal care products “such as shampoos, bath products, and eye and facial cleansers,” it can produce low-level irritation in the face, neck, and hands.
▸ 2003: Bacitracin. Dr. Cohen said about 9% of people who undergo patch tests and 1% of the general population are sensitive.
▸ 2002: Thimerosal. This substance was actually designated “non-Allergen of the Year,” according to Dr. Cohen. Removed from many products, it can still be found in most flu shots, he said. All told, 91% of thimerosal-allergic individuals have had “no reaction whatsoever” to flu shots, and the remaining 9% had only an injection site reaction.
▸ 2001: Gold. The second most common metal allergy in North America, gold allergy affects mostly women, said Dr. Cohen. About 10% of patients who take patch tests are allergic.
▸ 2000: Disperse Blue. One in five people tested for allergies to textile dyes were allergic to either blue or red, according to Dr. Cohen. Reactions to blue dyes were more than three times as common as to red. The acetate liners in clothing can be a problem for these people.
The ceremonial tattoos that use pure henna, such as those in India, are safe. DR. COHEN