p‐Phenylenediamine and other hair dye sensitizers in Spain

Background. Oxidative hair dyes are important skin sensitizers, causing contact allergy and dermatitis in hairdressers and consumers. Objectives. To study the prevalence of hair dye substances, categorized as potent skin sensitizers, in consumer‐available oxidative hair dye products on the market of a southern European country and to compare it with that in Sweden. Methods. Ingredient labels of 105 oxidative hair dye products from 19 brands were studied, and the prevalence and use pattern of hair dye substances, categorized as potent skin sensitizers, was assessed. Network diagrams were used to display results. Results. According to the labelling, all 105 products contained hair dye substances categorized as potent skin sensitizers. A total of 25 different hair dye substances categorized as potent skin sensitizers were identified. Eighty‐seven per cent of the products contained at least four such substances. Either p ‐phenylenediamine, toluene‐2,5‐diamine or toluene‐2,5‐diamine sulfate was present in 103 products. Conclusions. Hair dye substances categorized as potent skin sensitizers were used in all studied hair dye products on the Spanish market. The prevalence of p ‐phenylenediamine was higher in the present study than in a similar study in Sweden. More than 20 potent sensitizers were identified in each country. Not only p ‐phenylenediamine should be used to diagnose allergy to hair dyes.