ALLERGY TO COCAMIDOPROPYL BETAINE MAY BE DUE TO AMIDOAMINE - A PATCH TEST AND PRODUCT USE TEST STUDY

Cocamidopropyl betaine (CAPB) is an amphoteric surfactant commonly use d in personal care products and surface cleaners. Patch testing with c ommercially-available CAPB has yielded occasional reactions indicative of allergic contact dermatitis. To determine if subjects with previou s positive patch tests would react in provocative use tests of product s containing CAPB, and to study various contaminants in commercial CAP B supplies for allergenicity in these subjects, 10 subjects previously positive to CAPB on patch testing used a hair shampoo, hand soap, and body wash containing CAPB for 1-6 weeks or until a reaction developed . Later, they were patch tested to 2 different purity grades of CAPB a nd 3 possible manufacturing contaminants (dimethylaminopropylamine, am idoamine, and sodium monochloroacetate). 7 of the 10 subjects develope d dermatitis from 1 or more CAPB-containing products at some point dur ing the study. 9 of the 10 use-test subjects were then patch tested, a nd 6 of these subjects showed a reaction to amidoamine (0.1% aq.). Non e reacted to dimethylaminopropylamine (0.1% pet.). 1 subject reacted t o CAPB but not to amidoamine. In the follow-up patch testing with CAPB that was free of amidoamine, there were no positive reactions. Most s ubjects who were patch-test-positive showed a reaction when using CAPB -containing skin and hair care products. The chemical amidoamine, whic h is used in the synthesis of CAPB and which is a known contaminant of CAPB preparations, is likely to be the actual sensitizer in most case s rather than CAPB itself. The results do not rule out the possibility that CAPB itself may be an allergen in rare cases.