Sensitization to azo dyes: negative patch tests to yellow and red azo dyes in printed paper.

An over 2 x fold increase in para-aminoazobenzene allergy was observed in patients with allergic contact dermatitis during the years 1990-1991. Presuming that an increase in colour-printed newspapers might be a new unrecognized source of clinical allergy to azo dyes, patch tests were performed in 32 patients with an established p-aminoazobenzene allergy using a series of important azo dyes used in offset printing ink (Pigment Yellow 12, Pigment Yellow 13, Pigment Red 53, Pigment Red 57), as well as with dye-containing inks and specimens of colour-printed newspaper containing these azo dyes. In 25 out of the 32 patients (78%), positive patch tests were seen to textile azo dyes, in particular to Disperse Orange 3 (24 patients). In none of the 32 patients were reactions observed to the azo dyes used in printing ink, to the inks used or to the colour-printed paper specimens, indicating that these products were apparently not a cause of contact dermatitis in our group of patients with azo dye sensitization.