Provocative use tests in CAPB-allergic subjects with CAPB-containing product

Cocamidopropyl betaine (CAPB) has been identified as a cause of contact all ergy in personal care products. Furthermore, it has been suggested that che micals responsible are impurities, especially dimethylaminopropylamine (DMA PA). However, skin contact concentrations with these impurities, especially DMAPA, are very low. The aim of the study was to analyse whether subjects with previous positive patch tests to CAPB would react in provocative use t ests of a product containing CAPB. 10 individuals with a clinical history o f contact allergy to CAPB (by positive patch test and history) took part in a ROAT which used a CAPB-based shower gel at 25% (DMAPA concentration <1 p pm). None of the subjects showed positive allergic reactions. 1 of the test subjects did experience a flare of atopic dermatitis at the treatment site . Later, all 10 subjects were patch tested to 3 different concentrations of CAPB and DMAPA (0.1%, 0.3%, 1%) to verify the threshold that was capable o f inducing a positive test reaction. 5/10 showed clear + reactions to 1% CA PB (typically at D3), whilst a further 3 gave marginal and/or irritant reac tions. Only I of the subjects showed an allergic reaction to DMAPA. Finally , in uncontrolled use testing with the shower gel, none of the test subject s reported any adverse skin reactions. Thus, the study confirmed that CAPB- sensitive individuals can use a CAPB-based rinse-off product without the ri sk of experiencing an allergic reaction to CAPB.