NEW ORLEANS – Dimethyl fumarate – a volatile substance included in shipments of furniture, clothing, and shoes to inhibit growth of mold – earned the distinction as the American Contact Dermatitis Society's 2011 Allergen of the Year.
"We had a difficult decision," Dr. Donald V. Belsito said. "But we decided to go with dimethyl fumarate. It caused an epidemic in Europe starting in 2007."
The substance is now being regulated in Europe, "although apparently some stuff is still sneaking through," Dr. Belsito said. "To date, I know of no cases in the U.S., although Dr. Melanie Pratt has had a few cases in Ontario."
Dimethyl fumarate "produces an extremely severe dermatitis," said Dr. Belsito, a dermatologist in private practice in Shawnee, Kan.
The unlikely story behind identification of this preservative and fungicide demonstrates the benefits of international collaboration, he noted.
First noted by dermatologists in Finland, cases of the severe dermatitis began to appear in Sweden and the U.K. The severe rash, seen predominantly on the backs of the legs, buttocks, and back, was an etiologic mystery. Through extensive sleuth work, Finnish dermatologists determined a common link – each person recently purchased furniture from a particular Chinese manufacturer.
It then became commonly called "sofa dermatitis." A contact allergy to the upholstery fabric was initially suspected. However, no common chemical or fabric was identified among the different pieces of furniture purchased by affected patients.
Dr. Magnus Bruze, an occupational and environmental dermatologist at Malmo University in Sweden, and other investigators took apart the furniture, patch tested 40 affected patients to various components, and eventually identified the culprit: dimethyl fumarate. The allergen was enclosed in packets similar in appearance to silicone packets often labeled "Warning: Do Not Eat."
Dimethyl fumarate is so volatile it can vaporize within 6 weeks. The vapors cause the dermatitis – sometimes spread out and sometimes patchy – after permeating the sofas, clothing, and shoe products during shipment.
Particularly concerning is very low exposure levels to dimethyl fumarate can trigger a reaction, concentrations well below those of common contact dermatitis allergens.
In an unprecedented move, Dr. Belsito revealed the leading contender, at least for now, for the 2012 Allergen of the Year: acrylates and methacrylates. Acrylates and methacrylates are polymers and adhesives. Methacrylate, for example, is used as bone cement for prosthetic devices placed during orthopedic surgery. The ACDS is soliciting feedback from members about naming this class of compounds at their next Allergen of the Year.
Neomcyin was the 2010 Allergen of the Year. Dr. Belsito described neomycin reactions as "common, not readily recognized, and problematic." Neomycin was chosen because of its widespread use as an over-the-counter antibiotic product; its high propensity for cross-reaction with other agents in the aminoglycoside class, including gentamicin, kanamycin, and tobramycin; and because neomycin is included as a preservative in some vaccines. Because a neomycin allergy is not a type 1 IgE-mediated, a reaction results in eczema, not anaphylaxis and death.
Gold was the 2001 Allergen of the Year, and reactions to gold are common and clinically problematic. Bacitracin (2003) and glucocorticosteroids (2005) are other allergens that are both common and clinically relevant. In contrast, thimerosal (2002) is a common but nonrelevant allergen because it has been removed from most products in the United States. A reaction to mixed dialkyl thioureas (2009), used in production of rubber products, is relatively uncommon but important when it occurs.
Dr. Belsito said that he had no relevant disclosures.