Survey of sensitizing components of oxidative hair dyes (retail and professional products) in Germany

Abstract

Background: Components of oxidative hair dyes, such as p-toluylenediamine, are very potent contact sensitizers to which many consumers as well as hairdressers and their clients are commonly exposed. Methods: Based on the qualitative composition of both retail and professional hair-care products as determined by package labeling (according to INCI), we conducted a survey on the exposure to active components of oxidative hair dyes in Germany. The joint occurrence of components is also discussed. Results: Nearly all of the 20 most commonly used substances are potent or very potent contact sensitizers. Contained in 88 % of all products, p-toluylenediamine is the most common component. There are only minor differences between retail and professional products. A frequent combination of substances includes p-toluylenediamine (sulfate), resorcinol as well as m-aminophenol. However, their actual concentrations (which were not investigated in this study) may vastly differ depending on the shade of the individual hair dye. Conclusions: Descriptive univariate analysis reveals that the currently used patch test series ``Hairdressing Chemicals'', as recommended by the German Contact Allergy Research Group (DKG), does not adequately cover the spectrum of allergens consumers and professionals are exposed to. Other studies have also suggested that a number of other allergens should be tested as well. Taking into account the dynamic kinetics of oxidative hair dyes with respect to allergy development, the effects of combined simultaneous exposure to multiple allergens on the risk of sensitization requires further research.