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.
Benzophenone was announced as the 2014 Allergen of the Year in the journal Dermatitis earlier this year. Benzophenones are ultraviolet light filters. They are often used in the printing, cosmetics and sunscreens. In printing benzophenones are used in inks and clear coatings to protect materials from UV light. It is also added to some clear plastics to protect contents that would otherwise need to have dark packaging. They have been associated with various skin reactions including contact dermatitis and hives. “Benzophenones as a group have been named the American Contact Dermatitis Society’s Allergen of the Year for 2014 to raise awareness of both allergy and photoallergy to these ubiquitous agents.” The EPA fact sheet on sunscreens can be found here. A CDC fact sheet on benzophenone can be found here.
When contact dermatitis occurs, 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.