Since 2000, the American Contact Dermatitis Society names an “Allergen of the Year” to draw attention to chemicals often causing contact dermatitis. Contact dermatitis is an allergy that has a different mechanism than allergies like hayfever or peanut, which are often immediate in the onset of symptoms. Contact dermatitis is a delayed allergic reaction and usually arises 24-48 hours after exposure. It produces an itchy red rash that can blister, and it often takes several days to weeks for the rash to dry up and flake off. There is a joke that contact dermatitis goes away in 14 days or you can take steroids and it goes away in two weeks. (Got to love medical humor, right. Insert wife’s eye roll here.) The reality is steroids can often resolve the rash and symptoms more quickly.
Methylisothiazolinone (MIT) was announced as the 2013 Allergen of the Year in the journal Dermatitis earlier this year. MIT is a biocide often used to control mold or bacterial growth. It is found in industrial uses, food packaging and cosmetic products, and its use has risen in the past decade. Although tolerance and residue limits have been established and are regulated by the FDA and EPA, there is still a concern for increased skin sensitization because of increased exposure. Studies have estimated the population frequency of MIT allergy is 1.5%. The EPA fact sheet on MIT can be found here.
Patch testing (various allergens are taped to one’s back for several days) is the diagnostic procedure of choice when identification of the causative agent is not obvious. Once the chemical is identified, avoidance is key to prevent recurrences.
Past Contact Dermatitis Society Allergens of the Year:
2000 Disperse blue dyes
2004 Cocamidopropyl betaine
2009 Mixed dialkyl thiourea
2011 Dimethyl fumarate
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Disclaimer: This blog is not intended to create a doctor-patient relationship with any reader. If you need personalized medical advice, contact your primary care physician or other physician in your community.