Combined sensitizations to different azo dyes, probably based both on true cross-sensitization and on simultaneous positive reactions, have frequently been described. However, since azo dyes are included in the standard series in a minority of countries, the case studies considered comprise, with few exceptions, a small number of subjects. The aim of our study was to investigate cross-reactions between different azo dyes and para-amino compounds in azo-dye-sensitive subjects, to study the clinical aspects of azo dye dermatitis, to assess the relevance of sensitization to azo dyes, and to relate the pattern of cross-sensitizations to the chemical structure of the different dyes. Out of 6203 consecutively tested patients, 236 were sensitized to at least 1 of 6 azo compounds employed as textile dyes, included in our standard series. 107 subjects reacted to Disperse Orange 3 (DO3), 104 to Disperse Blue 124 (DB124), 76 to p-aminoazobenzene (PAB), 67 to Disperse Red 1 (DR1), 42 to Disperse Yellow 3 (DY3), and 31 to p-dimethylaminoazobenzene (PDAAB). Co-sensitizations to para-phenylenediamine were present in most subjects sensitized to DO3 (66%) and PAAB (75%), in 27% and 36% of DR1 and DY3-sensitive subjects, and only in 16% of subjects sensitized to DB124. Apart from the hands and the face, the neck and the axillae were the most frequently involved skin sites. Whereas the involvement of flexural areas was mainly connected with sensitization to DB124, in patients with hand dermatitis and in those working as hairdressers, sensitization to DO3 and PAAB was more frequent. Moreover, in the former patient group, a history of textile dye allergy was most frequently obtained. Out of 33 patients tested with an additional textile dye series, only 5 subjects reacted to anthraquinone dyes. Cross-sensitizations between azo dyes and para-amino compounds can partially be explained on the basis of structural affinities.

We have described 100 subjects sensitized to textile dyes. Of these, 16 had clinically been suspected of having a textile dermatitis from among 1145 patients referred for patch testing. 41 patients were identified from among 861 consecutive subjects tested with the GIRDCA (Italian Research Group on Contact and Environmental Dermatitis) standard series supplemented with 4 disperse dyes (Disperse Blue 124, Disperse Red 1, Disperse Yellow 3, Disperse Orange 3). The remaining 43 patients were identified from among 746 subjects tested with the GIRDCA standard series, supplemented with the 4 disperse dyes mentioned above and a further series of 12 other textile dyes. The clinical picture was extremely variable: most patients had a typical eczematous dermatitis, but we also observed persistent erythematous-wheal-type reactions, a transient urticarial dermatitis and an erythema-multiforme-like eruption. Among these textile dyes, Disperse Blue 124 caused most reactions. With the addition of the 4 disperse dyes to the GIRDCA standard series, we identified 4.8% sensitized to textile dyes, a much higher figure than the 1.4% observed among patients being patch tested on the basis of their history and the clinical findings; the addition of a further 12 textile dyes to the series further increased the detection rate to 5.8%. We stress the importance of routinely patch testing with textile dyes, which can help to elucidate the cause of certain kinds of atypical dermatitis.

Our study concerns contact sensitization in children, the frequency of which is still debated in the literature, even though specific reports are increasing. During a 7 year period (1988)(1989)(1990)(1991)(1992)(1993)(1994) 670 patients, 6 months to 12 years of age, were patch tested with the European standard series, integrated with 24 haptens, at the same concentrations as for adults. We observed positive results in 42% of our patients. Thimerosal, nickel sulfate, Kathon CG, fragrance mix, neomycin, wool alcohols, and ammoniated mercury induced most of the positive responses. The highest sensitization rate was found in children from 0 to 3 years of age.Comments on main positive haptens are reported. Seventy-seven percent of our sensitized patients were atopics, suggesting that atopy represents a predisposing factor for contact hypersensitivity. Patch testing represents a useful diagnostic procedure for the definition of childhood eczematous dermatitis and for the identification of agents inducing contact sensitization which is frequently associated with atopic dermatitis.Allergic contact dermatitis in children is no longer considered rare and specific reports in the literature are increasing (1-23). However, so far, the real frequency of contact sensitization in children has not been thoroughly investigated, since patients with dermatitis in this age group are not routinely patch tested.Moreover, it is sometimes difficult to compare the results of studies dealing with contact dermatitis in children, owing to differences both in the selection criteria and age of patients, and in the choice of test substances, their concentration, and the duration of the patch test application.In this study we illustrate the results obtained by patch testing pediatric patients during a 7 year period in the

593 recruits selected by the Military Health Service as being healthy and without a history of present or previous dermatitis, or ocular refraction defects, were patch tested with the GIRDCA (Italian Research Group on Contact and Environmental Dermatitis) standard series. Of these, 336 were also patch tested with substances used in the processing and dyeing of textiles and prick tested with 8 major allergens. 74 (12.5%) reacted to 1 or more substances. The most frequent sensitizers were: thimerosal (28 cases), ammoniated mercury (7 cases), phenol-formaldehyde resin (6 cases), parabens, nickel and Disperse Red 17 (4 cases each). 113 recruits reacted to 1 or more prick test allergens. We have demonstrated the importance of establishing such reference values in healthy groups for the correct evaluation of data collected from selected groups.

Reactive dyes are used especially for colouring natural fibres (cotton, silk and wool) that are widely used in Western countries, particularly Italy, in the production of clothes. The aim of our study was to investigate sensitization to the most commonly used reactive textile dyes in patients undergoing patch tests, and to assess the clinical relevance of contact sensitization to these dyes. 1813 consecutive patients underwent patch tests with the GIRDCA standard series and an additional textile series of 12 reactive dyes. 18 of these patients were sensitized to reactive dyes (0.99%) (4 only to reactive dyes). The dyes most frequently responsible for positive patch tests were Red Cibacron CR and Violet Remazol 5R (respectively, 8 and 5 positivities). In 5 cases only was a history of intolerance to particular garments given; of 4 patch tests performed with pieces of garment, 2 were positive. In 1 occupationally-exposed patient, airborne contact dermatitis was suspected. Owing to the lack of up-to-date patch test series, some cases of allergic contact dermatitis from textile dyes are probably misdiagnosed: new colouring agents are continuously introduced to the market, so that a close relationship with textile industry is necessary to improve our diagnostic tools.