Contact allergy to textile dyes. Clinical and experimental studies on disperse azo dyes

University dissertation from Occupational and Environmental Dermatology Unit

Abstract: Disperse dyes are the most common allergens among textile dyes. It is not known whether the purified dyes, impurities in the commercial dyes, or metabolites are the actual sensitisers. Moreover, it is not known whether those disperse dyes that are now present in test series are actually used in textile dyeing today. The aim of this thesis was A) to evaluate the significance of the impurities found in the commercial dyes Disperse Orange 1 and Disperse Yellow 3 and their potential metabolites from azo reduction regarding contact allergy; B) to investigate the sensitising capacity of Disperse Orange 1 and its metabolites and their cross-reactivity to Disperse Yellow 3, its metabolites, and PPD; and C) to determine whether eight disperse dyes, hitherto the most widely quoted as allergenic, are still used in textiles sold in various countries all over the world. Evaluation of the many published studies on contact allergy to disperse dyes used for dyeing textiles was also performed. It was shown that the commercial dyes Disperse Orange 1 and Disperse Yellow 3 each contain at least one impurity acting as a sensitiser. Positive patch test reactions to Disperse Orange 1 and Disperse Yellow 3 were linked to positive reactions to some of their metabolites: p-aminodiphenylamine and 2 –amino-p-cresol, respectively. It was found that Disperse Orange 1 and p-aminodiphenylamine are strong sensitisers and cross-react with each other in the guinea pig maximisation test. PPD, 4-nitroaniline, 4-aminoacetanilide, 2-amino-p-cresol, or Disperse Yellow 3 did not show any cross-reactivity to them. Our observations did not directly support the metabolite theory, and the results regarding elicitation thresholds spoke against this theory. Available data in the medical literature indicated that positive patch test reaction prevalence rates to Disperse Blue 106 and 124, and Disperse Orange 3 were over 1% when screening dermatitis patients. From 121 analyzed items, Disperse Yellow 3, Disperse Blue 124 and 106 and Disperse Orange 1 were detected in three garments made in the European Union and India.

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