An animal model assessment of common dye-induced allergic contact dermatitis.

Dyes are a category of substances capable of inducing allergic contact dermatitis found in a variety of foods, drugs, textiles, cosmetics, and hair dyes. This study tested 33 dyes in guinea pigs using a modified Buehler and Klecak method for open epicutaneous testing. The dyes were tested at an induction concentration of 10% and challenge concentrations of 10.0%, 5.0%, and 2.5%. Nine of the 33 dyes tested produced positive allergic reactions in the guinea pig model (2-amino-4-nitrophenol, 2-amino-5-nitrophenol, acid yellow 23, acid orange 3, basic black 3, basic orange 1, disperse orange 3, solvent black 27, and solvent black 34). When eight of the nine positive dyes were retested using a 1% induction concentration, five dyes produced allergic contact dermatitis at a 1% challenge concentration (2-amino-4-nitrophenol, 2-amino-5-nitrophenol, acid yellow 23, disperse orange 3, and solvent black 34), two at a 0.5% challenge concentration (2-amino-5-nitrophenol and solvent black 34), and one at a 0.25% challenge concentration (2-amino-5-nitrophenol). DNCB at a 0.5% induction/challenge concentration was used as a positive control. With the exception of disperse orange 3 and acid yellow 23, the seven additional dyes that elicited positive allergic reactions in the guinea pig model have not been previously reported.