Many allergens are involved in contact dermatitis of clothing and footwear. Shoes include rubbers, dyes, glues and leather, and a wide range of components, which depend on the epidemiological and geographical situation of the individual.1–3 In textiles, the azo dyes are mainly responsible for acute clinical reactions requiring medical intervention,3 while synthetic resins mainly cause chronic reactions.4 Other substances used in their manufacture, such as vulcanisation accelerators, elastic, and decorative objects occasionally cause allergy.1
A 56-year-old Caucasian male patient, bus driver, admitted after widespread eczema, predominantly acral, which was confirmed on histological examination. He received outpatient treatment with betamethasone, and subsequently he was readmitted for microbial eczema of the feet that spread through the trunk and the extensor surface of the upper and lower limbs. He was treated with prednisolone 20mg and flucloxacillin, as well as washing with potassium permanganate. Mycological examination of scales of the feet was negative. In his profession, he wore shoes with black rubber soles and a dark blue suit of synthetic fabric which we later discovered was part of his uniform. He denied personal and family history of atopy.
The patch test was performed with the basic adopted by GPEDC (Grupo Português de Estudo das Dermites de Contacto) and shoes series (both from Chemotechnique diagnostics 2009 (Malmö, Sweden)).
Analysing the results obtained, IPPD is an anti-ozonant for the vulcanisation of black rubber and, also related with shoes, 1,3-diphenylguanidine and n-dodecyl mercaptan are vulcanisation accelerators of natural and synthetic rubber, respectively. The Disperses Blue 106 and D. Orange 1 are clothing dyes, as well as D. Orange 3, D. Yellow 3, D. Red 1, D. Blue 3, also commonly used in socks, and Acid Yellow 36 which is regularly used in shoes. There was no reaction to PPD.
In order to better understand the patient's reaction and to evaluate the use of the uniform (dark blue synthetic fabric) without any other material composition we carried out a patch test series of textile dyes (textile dyes and resins) using fragments of the individual clothes (Table 1)
Readings at 48 and 96h of the following series: basic, textile, fragments of the individual clothes and shoes.
| D2 | D4 | |
| Basic series | ||
| IPPD 0.1% pet | +++ | +++ |
| Disperse Blue 106 (1% pet) | ++ | ++ |
| PPD 1% pet | − | − |
| Disperse Orange 1 (1% pet) | +++ | +++ |
| Shoe series | ||
| D. Orange 3 (1% pet) | ++ | +++ |
| D. Yellow 3 (1% pet) | ++ | +++ |
| D. Red 1 (1% pet) | ++ | +++ |
| D. Blue 3 3 (1% pet) | ? | +++ |
| Diphenylguanidine (1% pet) | ++ | +++ |
| Acid Yellow 36 (1% pet) | +++ | +++ |
| Dodecyl mercaptan (0.1% pet) | ++ | +++ |
| Textile dyes and resins | ||
| 4-Aminoazobenzene (0.25% pet) | +++ | +++ |
| Disperse blue-124 (1% pet) | ++ | +++ |
| Disperse yellow-9 (1% pet) | − | + |
| Disperse black-1 (1% pet) | ? | ++ |
| Fragment of blue suit (as is) | − | − |
| Fragment of blue socks(as is) | − | − |
N-isopropyl-N′-phenyl-p-phenylenediamine (IPPD) is an anti-ozonant of rubber vulcanisation and the major allergen of black rubber, and was assumed to be responsible for the onset of the feet eczema, once the patient was wearing shoes with black rubber soles.
1,3-Diphenylguanidine is also a vulcanisation accelerator for natural rubber as well as n-dodecyl mercaptan for synthetic rubber, since both components exist in the shoes, it could explain a concomitant sensitisation process due to their different chemical structures. 1,3-Diphenylguanidine can be an irritant substance in the patch tests and may give false positive reactions. In our case the result was a delayed reaction to this component as seen in the increase response comparing the reading at D2 and D4.
IPPD has structural similarity to PPD and may therefore cross-react with it,5 and in this case it is not proved. Allergy to textile dyes can be caused by the allergen transfer to the skin or by the formation of metabolites after epidermal penetration.6,7 The final colour is often obtained from the combination of several dyes. The colour of the culprit dye often bears no relationship to the colour of the offending garment. Thus, a blue suit caused dermatitis from a disperse yellow dye used as one component of the final blue colour. The dyes are classified according to their applications. The main allergenic dyes are the dispersed ones, and they come from the azoic (azo) anthraquinone and nitroarylamine (nitro) chemical classes.6
The dispersed azo compounds are only partially soluble in water and they are used for dyeing synthetic fibres such as polyesters, acrylics, acetates and sometimes the nylon socks. They are never used in natural fibres.7 They are characterised by a double bond NN. This bond has the distinction that in vivo it can be broken down into two amines, which can then be metabolised into haptens.
The disperse yellow-3, disperse orange-1 and disperse red-1, and also disperse blue 106 and 124 are azo dyes. Disperse orange 3 is a dye used in some socks, 66% patients sensitised to this component also react to the PPD, and this can happen by the metabolic conversion of textile dyes in the skin to PPD.1 They also react to solvent yellow 1 which contains 4-aminoazobenzene and p-dimethyl-4-aminoazobenzene. Azo dyes are characterised by R1NNR2 chemical structures. The rupture of the azoic dye bond is interpreted as a concomitant reaction and not like a cross-reaction, although the allergen formed is the same in both cases.8,9
In this patient, the possibility of concomitant reaction or cross-reactivity with disperse dyes has facilitated sensitisation to azo and anthraquinones, whose structures contain a core metabolised benzene which can form PPD.10 Was thought that dye nitroarylamine (nitro) is a co-sensitisation because it is a different one of the chemical classes of the disperse dyes.6
The patient is recommended to avoid wearing clothes of synthetic fibres in direct contact with the skin and especially for dark colours, and with black rubber shoes also.
Ethical disclosuresPatients’ data protectionConfidentiality of Data. The authors declare that they have followed the protocols of their work centre on the publication of patient data and that all the patients included in the study have received sufficient information and have given their informed consent in writing to participate in that study.
Right to privacy and informed consentRight to privacy and informed consent. The authors have obtained the informed consent of the patients and/or subjects mentioned in the article. The author for correspondence is in possession of this document.
Protection of human subjects and animals in researchProtection of human and animal subjects. The authors declare that the procedures followed were in accordance with the regulations of the responsible Clinical Research Ethics Committee and in accordance with those of the World Medical Association and the Helsinki Declaration.
