Nickel tops list as cause of contact dermatitis

A Mayo Clinic team has compiled a top-10 list of the most frequent allergen that causes contact dermatitis. The allergens appear in a wide array of products, Dr. Mark D. P. Davis said at the American Contact Dermatitis Society, held in conjunction with the American Academy of Dermatology's annual meeting, underway in San Francisco, California.

Davis and colleagues reviewed the results of skin patch testing conducted between 2001 to 2004 in a total of 1,632 Mayo Clinic patients seem for contact dermatitis.

Patients underwent skin patch testing for up to 71 allergens. The investigators found that 71.8 percent of patients had at least one positive reaction and 52.3 percent had two or more positive results. "Our list evolved over time," incorporating substances that tested positive most frequently, Davis said.

The 10 most commonly identified allergens were nickel sulfate hexahydrate, balsam of Peru, cobalt chloride, neomycin sulfate, gold sodium thiosulfate, "fragrance mix," thimerosal, formaldehyde, benzalkonium chloride and potassium dichromate.

"We put the positive allergens in a computer database, the Computerized Allergen Replacement Database, to identify combinations used in specific products," Davis told Reuters Health.

"What clinicians need to do is sit the patient down and go over the list (of positive allergens)], asking about patterns of dermatitis - such as where the (inflamed) areas are and when they occur. Then, the patient must be actively interviewed to determine what products they use and to counsel them on what things to avoid and what things they can use, and to teach them to read labels for ingredients."

Soaps in particular tend to have a lot of fragrances and preservatives, the investigator mentioned.

Identifying culprit products "is a very labor-intensive process and the patient must be actively involved," Davis explained.

"Just last week, we had a case of a young boy who had a raging dermatitis just below the navel. We found out that that is where the metal button on his jeans hit. He started covering the metal backing with a band aid," Davis related.