A nickel for your thoughts: Contact dermatitis comes from variety of sources

Key Points

Speaking at the annual meeting of the Canadian Dermatology Association on "What's New in Contact Dermatitis," Joel DeKoven, M.D., a dermatologist at Sunnybrook Health Sciences Center in Toronto and associate professor in the department of medicine at the University of Toronto in Toronto, said that there are rising sensitization rates to nickel across many jurisdictions, as well as increasing rates of nickel allergy.

Indeed, the American Contact Dermatitis Society has named nickel the "allergen of the year" for 2008.

Patch testing

The North American Contact Dermatitis Group reported results of patch testing conducted between January 2003 and December 2004. Patients were tested with a series of 65 allergens, considered a screening tool in the evaluation of contact dermatitis.

A total of 5,148 patients were tested, and 66.7 percent had at least one positive reaction. Nearly half of the patients (44.4 percent) were diagnosed with primary allergic contact dermatitis.

The results showed that allergies to nickel, budesonide, mercaptobenzothiazole, and paraben mix were at least 1.12 times more common.

Exceptionally, Europe is not seeing these increased sensitization rates, as measures have been put in place to regulate acceptable levels of nickel content and rates of nickel release from nickel-containing objects such as jewelry and coins, Dr. DeKoven says.

"We don't have any form of nickel content regulations in North America," he says.

Sources of contact

Though contact allergic dermatitis to nickel can develop at any age, a suspected cause of the rising incidence in nickel allergy is the popularity of body piercing. The number of piercings appears to correlate with the risk of developing a contact nickel allergy.

Apart from jewelry, other common sources of nickel sensitization include belt buckles, zippers, snaps, clasps and other clothing fasteners.

The dimethylglyoxime spot test may be used by physicians and patients to test for the presence of nickel, possibly down to 10 parts per million, a level that can elicit an allergic contact skin reaction in sensitized individuals.

The burgeoning use of cellular phones has also brought to light cases of contact dermatitis, Dr. DeKoven tells Dermatology Times.

Those reports of cell phones and associated contact have prompted investigators to report the use of spot testing for nickel on various brands of mobile phones. Nickel has been detected on cellular phone headsets and cellular phone screens, as well as the keypads - and spot tests have proven positive.

With cellular phone use growing, particularly in youths, clinicians are likely to see more cases of contact dermatitis arising from cell phone use, Dr. DeKoven says.

Non-metal sources

Increasingly, non-metal sources are being linked to cases of contact dermatitis. Those sources include footwear, such as Crocs®, shellac in mascara, and additives in polyvinyl chloride (PVC) gloves.

PVC gloves may contain the antimicrobial Benzisothiazoline. There have been some recent cases reported of contact allergy due to Benzisothiazoline in PVC gloves, especially in dental personnel.

In the last year, there have also been more cases of contact allergy to adipic polyester, a polymer of adipic acid and propylene glycol used as a plasticizer in PVC gloves.

These substances join Bisphenol A, an antioxidant in plastics, as being part of a group of potential allergens that may be encountered in PVC gloves.

Dr. DeKoven describes pentylene glycol as an "emerging allergen," noting that it is present in many cosmetic creams as a preservative and humectant.

Some popular moisturizers frequently recommended by dermatologists have been cited as causing allergic contact dermatitis secondary to sensitization to pentylene glycol.

Dr. DeKoven says a heightened awareness of newly described sources of contact sensitization may help dermatologists solve cases that, up to this point, may have been "contact conundrums."