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.