Principles and methodology for identification of fragrance allergens in consumer products

Fragrances contain several hundreds of different chemicals, a few major and many minor, which are responsible for the complexity of the odour. Fragrances are a major cause of allergic contact dermatitis. As a diagnostic tool, the current fragrance mix is very useful though not ideal. A 50-year-old woman presented with a pruriginous, erythematous eruption, characterized by papules, vesicles, exudation and crusting over the neck and chest. With the suspicion of fragrance allergy, patch testing was performed. Initially, the only positive reaction observed was with her own eau de toilette named Woman. The TRUE Test fragrance mix patch test was negative. Chemical fractionation of Woman perfume concentrate was combined with a sequenced patch testing procedure and with structure-activity relationship studies. Ingredients supplied by the manufacturer were also included in the study. Benzophenone-2, Lyral, alpha-hexyl cinnamic aldehyde and alpha-damascone were found to be responsible for the patient's contact allergy to the commercial product. These substances contain chemical structural alerts giving them antigenic ability. The common use of new chemicals to manufacture fragrances, and the increased number of patients sensitive to them but with negative fragrance mix reactions, makes it necessary to identify new potential fragrance sensitizers in commercial products.