p-Phenylenediamine and other allergens in hair dye products in the United States: a consumer exposure study.

BACKGROUND Hair dye products constitute an important source of allergen exposure, and contribute importantly to allergic contact dermatitis in consumers and hairdressers. OBJECTIVES To evaluate the presence of potent contact sensitizers in oxidative hair dye products intended for home use on the US market. METHODS Ingredient labels of 107 hair dyes from 10 major brands were examined and used to assess the prevalence of hair dye substances known to be potent contact sensitizers. RESULTS One hundred and six of 107 (99%) products contained at least one potent sensitizer, and the average product contained six (range 0-11). p-Phenylenediamine (PPD) was found in 83 products (78%), but resorcinol (89%), m-aminophenol (75%), p-aminophenol (60%) and toluene-2,5-diamine (21%) were also frequently identified. CONCLUSIONS Potent contact sensitizers were almost universally included in the hair dyes investigated in the United States. Although PPD is a common allergen, resorcinol and m-aminophenol were found more frequently. In total, 30 potent sensitizers were found. Clinicians should consider other allergens in addition to PPD when evaluating patients with suspected hair dye allergy.