Is p-Phenylenediamine Still a Prevalent Contact Allergen in Spain?

Abstract Objectives To analyze trends in the prevalence of contact sensitization to p-phenylenediamine between 2004 and 2014, taking into consideration that the concentration of this product in cosmetics was regulated in 2009. To explore risk factors for contact allergy to p-phenylenediamine. Materials and methods Retrospective observational study of patients suspected of having contact dermatitis from allergy to p-phenylenediamine during the years between 2004 and 2015 in 8 tertiary level hospitals. The patients underwent patch testing (TRUE-test) with the standard series of the Spanish Research Group on Contact Dermatitis and Skin Allergies. This series included p-phenylenediamine 1%. We followed international recommendations for the statistical analysis of data related to contact allergies. Results Three hundred eighty-six out of 9341 patients (4.1%) had positive reactions to p-phenylenediamine. The prevalence tended to decrease in the early years (2004–2007) and then leveled off at around 4%. Risk factors for developing contact dermatitis from p-phenylenediamine were sex, age over 40 years, multiple sensitivities, and profession, notably workers in hair salons and those who handle rubber and plastics. Conclusions The prevalence of p-phenylenediamine allergy remains high among patients with contact eczema. Risk factors for p-phenylenediamine contact allergy are consistent with previous reports.