Prevalence of contact allergy to non-disperse azo dyes for natural fibers - A study in 1814 consecutive patients

5 non-disperse azo dyes, used for colouring natural fibers, were added to the standard patch test series, as 5% pet. preparations. 1814 consecutive patients attending the patch test clinic were patch tested, of whom 16 (0.88%) reacted to the newly added dyes: 8 to Direct Orange 34, 5 to Acid Yellow 61, 2 to Acid Red 359 and 1 to Acid Red 118. On the basis of clinical history and results of patch tests with pieces of fabrics, contact sensitization to non-disperse azo dyes seemed to be related to the appearance of skin lesions at least in 8 subjects. We conclude that systematic exploration of the sensitizing potential of textile dyes, selected after careful investigation, can provide additional information on the frequency of occurrence of textile dye dermatitis, supporting individual investigation in sensitized subjects.