Disperse blue dyes 106 and 124 are common causes of textile dermatitis and should serve as screening allergens for this condition

Investigating sensitization activity of azobenzene disperse dyes via the Direct Peptide Reactivity Assay (DPRA)

Azobenzene disperse dyes are the fastest-growing category of commercial dyestuffs and have been found in indoor house dust and in children's polyester apparel. Azobenzene disperse dyes are implicated as potentially allergenic; however, little experimental data is available on allergenicity of these dyes. Here, we examine the binding of azobenzene disperse dyes to nucleophilic peptide residues as a proxy for their potential reactivity as electrophilic allergenic sensitizers. The Direct Peptide Reactivity Assay (DPRA) was utilized via both a spectrophotometric method and a high-performance liquid chromatography (HPLC) method. We tested dyes purified from commercial dyestuffs as well as several known transformation products. All dyes were found to react with nucleophilic peptides in a dose-dependent manner with pseudo-first order kinetics (rate constants as high as 0.04 h-1). Rates of binding reactivity were also found to correlate to electrophilic properties of dyes as measured by Hammett constants and electrophilicity indices. Reactivities of polyester shirt extracts were also tested for DPRA activity and the shirt extracts with high measured abundances of azobenzene disperse dyes were observed to induce greater peptide reactivity. Results suggest that azobenzene disperse dyes may function as immune sensitizers, and that clothing containing these dyes may pose risks for skin sensitization.

Recent advances in toxicological research and potential health impact of microplastics and nanoplastics in vivo

As emerging pollutants, direct and indirect adverse impacts of micro(nano)plastics (MPs/NPs) are raising an increasing environmental concern in recent years due to their poor biodegradability and difficulty in recycling. MPs/NPs can act as carriers of bacteria, viruses, or pollutants (such as heavy metals and toxic organic compounds), and may potentially change the toxicity and bioavailability of pollutants. Ingested or attached MPs/NPs can also be transferred from low-trophic level organisms to high-nutrient organisms or even the human body through the food chain transfer process. This article reviews the emerging field of micro- and nanoplastics on organisms, including the separate toxicity and toxicity of compound after the adsorption of organic pollutants or heavy metals, as well as possible mechanism of toxicological effects and evaluate the nano- and microplastics potential adverse effects on human health. The inherent toxic effects MPs/NPs mainly include the following: physical injury, growth performance decrease and behavioral alteration, lipid metabolic disorder, induced gut microbiota dysbiosis and disruption of the gut's epithelial permeability, neurotoxicity, damage of reproductive system and offspring, oxidative stress, immunotoxicity, etc. Additionally, MPs/NPs may release harmful plastic additives and toxic monomers such as bisphenol A, phthalates, and toluene diisocyanate. The vectors' effect also points out the potential interaction of MPs/NPs with pollutants such as heavy metals, polycyclic aromatic hydrocarbons, organochlorine pesticides, polychlorinated biphenyls, perfluorinated compounds, pharmaceuticals, and polybrominated diphenyl ethers. Nevertheless, these potential consequences of MPs/NPs being vectors for contaminants are controversial.

Analysis on advances and characteristics of microplastic pollution in China's lake ecosystems

China is the largest producer and consumer of plastics worldwide. Microplastic (MP) pollution has been a recent research hotspot in environmental science and ecology. This study collects and analyzes the statistical data for microplastics (MPs) 86 lakes in entire China's lake ecosystems in past five years (2016-2020), their range in area is 0.056-4543.000 km² (average: 566.045 km²), and the water storage varies from 0.162 × 10⁸ to 1050.000 × 10⁸ m³ (average: 77.884 ×10⁸ m³). The results showed (1) The MP abundance in lake surface water is significantly correlated with lake area (ρ = -0.562, p ＜0.01), provincial GDP (Gross Domestic Product, GDP) (ρ = 0.377, p = 0.002), GDP per capita (ρ = 0.346, p = 0.006), urban waste water discharge and ratio of agricultural land area (ρ = 0.369, p = 0.003). (2) The MP abundance in lake sediment is significantly correlated with per capita domestic volume of garbage disposal (ρ = -0.536, p ＜0.001), per capita urban waste water discharge (ρ = -0.544, p ＜0.001) and ratio of agricultural land area (ρ = 0.635, p ＜0.001). (3) Irrespective of whether the samples were from surface water or sediment, MPs were primarily transparent, and the dominant types were fragments, films, and fibers. In addition, the size of MPs samples was mostly less than 2 mm, and the major polymers were polyethylene (PE), polypropylene (PP), and polystyrene (PS). (4) The degree of MP pollution in organisms was related to the degree of environmental pollution. These findings could provide a theoretical basis for the control and management of MP pollution in China's lake ecosystems.

Dynamics of airborne microplastics, appraisal and distributional behaviour in atmosphere; a review

The use of plastics is common across all aspects of human life owing to its durable and versatile nature. The generation and utilization of plastics are directly related to the anthropogenic activities. The extensive use of plastics and adoption of inappropriate waste-management frameworks has resulted in their release into the environment, where they may persist. Different environmental factors, such as, photochemical, thermo-oxidation, and biological degradation, can lead to the degradation of plastics into micro- (MPs) and nano-plastics (NPs). The behaviour and concentration of MPs in the terrestrial environment can depend on their size, density, and local atmospheric conditions. Microplastics and nanoplastics may enter the food web, carrying various organic pollutants, which bio-accumulate at different trophic levels, prompting organism health concerns. Microplastics being airborne identifies as new exposure route. Dietary and airborne exposure to MPs has led researchers to stress the importance of evaluating their toxicological potential. The primary goal of this paper is to explore the environmental fate of MPs from sources to sink in the terrestrial environment, as well as detail their potential impacts on human health. Additionally, this review article focuses on the presence of airborne microplastics, detailed sample pre-processing methods, and outlines analytical methods for their characterization.

Environmental occurrences, fate, and impacts of microplastics

Microplastics (MPs) are small plastic pieces with size less than 5 mm that have entered and polluted the environment. While many investigations including several critical reviews on MPs in the environment have been conducted, most of them are focused on their occurrences in marine environment. Current understanding on the occurrences, behaviors, and impacts of MPs in the terrestrial environment is far from complete. A systematic review of the literature was thus conducted to promote the research on MPs in the environment. This work is designed to provide a comprehensive overview that summarizes current knowledge and research findings on environmental occurrences, fate and transport, and impacts of MPs. In addition to discussing the occurrences, characteristics, and sources of MPs in the ocean, freshwater, sediments, soils, and atmosphere, the review also summarizes both the experimental and modeling data of the environmental fate and transport of MPs. Research findings on the toxic effects, bioaccumulation, and bioavailability of MPs in the environment are also covered in this critical review. Future perspectives are discussed as well.

Contact allergy to compression stockings: Is this possible?

In der Therapie der chronisch venösen Insuffizienz oder des Lymphödems sind Kompressionsstrümpfe ein Standard der Therapie. Trotzdem ist die Akzeptanz der Patienten relativ gering. Ein Grund dafür sind unter anderem auch Symptome wie Juckreiz, Brennen oder Rötung, die vom Patienten, aber auch häufig vom behandelnden Arzt als Allergie auf die Kompressionsstrümpfe gewertet werden. Die Übersichtsarbeit geht auf die Grundlagen der Kontaktallergien ein, zeigt wie häufig Allergien auf Kompressionsstrümpfe auftreten, welche Auslöser dafür in Frage kommen und beschreibt kurz die häufigen Differenzialdiagnosen, ihre Auslöser und Prävention.

Azo dyes and human health: A review

Synthetic azo dyes are widely used in industries. Gerhardt Domagk discovered that the antimicrobial effect of red azo dye Prontosil was caused by the reductively cleaved (azo reduction) product sulfanilamide. The significance of azo reduction is thus revealed. Azo reduction can be accomplished by human intestinal microflora, skin microflora, environmental microorganisms, to a lesser extent by human liver azoreductase, and by nonbiological means. Some azo dyes can be carcinogenic without being cleaved into aromatic amines. However, the carcinogenicity of many azo dyes is due to their cleaved product such as benzidine. Benzidine induces various human and animal tumors. Another azo dye component, p-phenylenediamine, is a contact allergen. Many azo dyes and their reductively cleaved products as well as chemically related aromatic amines are reported to affect human health, causing allergies and other human maladies.

Contact Dermatitis to Personal Sporting Equipment in Youth

Background:

Contact dermatitis to personal sporting equipment in youth is poorly studied.

Objective:

To review the results of patch testing 6 youth to their sporting equipment in a dermatology general private practice from 2006 to 2011.

Methods:

A retrospective analysis of 6 youth aged 11 to 14 who were evaluated for chronic and persistent dermatitis occurring in relation to sports equipment was conducted. All patients were subjected to epicutaneous (patch) testing, which included some or all of the following: North American Contact Dermatitis Group (NACGD) series, textile series, rubber series, corticosteroid series, and raw material from the patients’ own personal equipment.

Results:

All cases had 1 or more positive patch test reactions to an allergen within the aforementioned series, and 3 subjects tested positive to their personal equipment in raw form.

Conclusions:

Allergic contact dermatitis, not irritant, was deemed the relevant cause of chronic dermatitis in 4 of the 6 patients due to positive reactions to epicutaneous tests and/or personal equipment. The utility of testing to patients’ own sporting equipment was shown to be of additional value and should be considered when patch testing for contact allergy to sporting equipment.

Allergic contact dermatitis in children: which factors are relevant? (review of the literature)

Allergic contact dermatitis (ACD) in children is increasing. Sensitization to contact allergens can start in early infancy. The epidermal barrier is crucial for the development of sensitization and elicitation of ACD. Factors that may influence the onset of sensitization in children are atopic dermatitis, skin barrier defects and intense or repetitive contact with allergens. Topical treatment of ACD is associated with cutaneous sensitization, although the prevalence is not high. ACD because of haptens in shoes or shin guards should be considered in cases of persistent foot eruptions or sharply defined dermatitis on the lower legs. Clinical polymorphism of contact dermatitis to clothing may cause difficulties in diagnosing textile dermatitis. Toys are another potentially source of hapten exposure in children, especially from toy-cosmetic products such as perfumes, lipstick and eye shadow. The most frequent contact allergens in children are metals, fragrances, preservatives, neomycin, rubber chemicals and more recently also colourings. It is very important to remember that ACD in young children is not rare, and should always be considered when children with recalcitrant eczema are encountered. Children should be patch-tested with a selection of allergens having the highest proportion of positive, relevant patch test reactions. The allergen exposure pattern differs between age groups and adolescents may also be exposed to occupational allergens. The purpose of this review is to alert the paediatrician and dermatologist of the frequency of ACD in young children and of the importance of performing patch tests in every case of chronic recurrent or therapy-resistant eczema in children.

Patients presenting with miliaria while wearing flame resistant clothing in high ambient temperatures: a case series

Introduction

Clothing can be a cause of occupational dermatitis. Frequent causes of clothing-related dermatological problems can be the fabric itself and/or chemical additives used in the laundering process, friction from certain fabrics excessively rubbing the skin, or heat retention from perspiration-soaked clothing in hot working environments. To the best of our knowledge, these are the first reported cases of miliaria rubra associated with prolonged use of flame resistant clothing in the medical literature.

Case presentation

We report 18 cases (14 men and 4 women, with an age range of 19 to 37 years) of moderate to severe skin irritation associated with wearing flame resistant clothing in hot arid environments (temperature range: 39 to 50°C, 5% to 25% relative humidity). We describe the medical history in detail of a 23-year-old Caucasian woman and a 31-year-old African-American man. A summary of the other 16 patients is also provided.

Conclusions

These cases illustrate the potential serious nature of miliaria with superimposed Staphylococcus infections. All 18 patients fully recovered with topical skin treatment and modifications to their dress ensemble. Clothing, in particular blend fabrics, must be thoroughly laundered to adequately remove detergent residue. While in hot environments, individuals with sensitive skin should take the necessary precautions such as regular changing of clothing and good personal hygiene to ensure that their skin remains as dry and clean as possible. It is also important that they report to their health care provider as soon as skin irritation or rash appears to initiate any necessary medical procedures. Miliaria rubra can take a week or longer to clear, so removal of exposure to certain fabric types may be necessary.

Patch testing of patients allergic to Disperse Blue 106 and Disperse Blue 124 with thin-layer chromatograms and purified dyes

BACKGROUND

Former investigations have demonstrated that patch test preparations containing Disperse Blue (DB) 106 and DB 124 are impure.

OBJECTIVE

To investigate the significance of impurities in preparations of disperse dyes with regard to contact allergy.

MATERIALS/METHODS

21 patients allergic to DB 106 and/or DB 124 were tested with dilution series of commercial and purified DB 106 and DB 124. All patients were additionally tested with thin-layer chromatography (TLC) strips made from the commercial preparations containing DB 106 and 18 of them also with TLC strips containing DB 124.

RESULTS

13 of 21 and 12/18 patients tested positively to the strips of DB 106 and DB 124, respectively. Among these patients, 4/13 and 5/12, respectively, did not react to the main spot but reacted to other spots. Dilution series of purified DB 106 and DB 124 were positive in 10 patients each, while 16 and 15 patients, respectively, tested positively to the dilution series of the corresponding commercial disperse dye.

CONCLUSION

Approximately 25% of the patients, diagnosed as contact allergic to DB 106 and DB 124, only reacted to impurities in the patch test preparations. This has implications for diagnosis and prevention.

Allergic contact dermatitis in children: common allergens and treatment: a review

PURPOSE OF REVIEW

The following study reviews the recent literature pertaining to allergic contact dermatitis (ACD) in the pediatric population. This study also provides an overview of the most common allergens and discusses various therapeutic modalities.

RECENT FINDINGS

The pathophysiology of ACD is intricate and multifaceted, resulting in a characteristic, delayed inflammatory response. Although commonly recognized in adults, its existence in the pediatric population was questioned. Recent literature suggests that pediatric ACD exists and is more common than previously recognized. The diagnosis relies on the clinical presentation combined with appropriate use and interpretation of a patch test. Although many studies have investigated ACD in children, few have documented the relevance of positive patch test reactions until recently. The most current prevalence estimates of positive patch test reactions range from 14 to 70% of children patch tested. Although that range is broad, these studies have demonstrated the relevance of positive reactions and confirmed ACD as a disease entity in children.

SUMMARY

ACD is a previously underrecognized disease process in the pediatric population that can manifest as a serious dermatologic challenge for both patients and physicians. This review will address the prevalence, diagnostic methods, frequent allergens and treatment options in pediatric ACD.

Patch testing: pitfalls and performance

PURPOSE OF REVIEW

Contact dermatitis is a common disease process that includes allergic and irritant contact dermatitis. The gold standard for diagnosing allergic contact dermatitis, a type IV delayed hypersensitivity reaction, is patch testing. Patch testing is not a difficult procedure, however, there are several critical components that determine the success of the test: having an appropriate level of suspicion for the diagnosis of allergic contact dermatitis, an adequate threshold for patch testing, the necessary experience to properly interpret the results and to determine their relevance, and the ability to thoroughly educate the patient about the condition.

RECENT FINDINGS

Research shows that patch testing practices differ among individuals and specialties. The level of patch testing education, interest in, and experience with, the procedure can affect the results of the test. Some of these practice differences and how they affect the outcome of patch testing are highlighted.

SUMMARY

Physicians' knowledge and experience with patch testing, their level of interest and access to allergens will determine the performance of this test, the reliability of the results and the benefits gained from this procedure.

Contact allergy to textile dyes in southern Sweden

Contact allergy to disperse dyes in textiles is documented in prevalence studies from southern Europe. To evaluate the prevalence of allergic patch test reactions to different textile dyes in southern Sweden, and to look at the sites of dermatitis in individuals hypersensitive to textile dyes, we retrospectively investigated 3325 consecutively patch-tested patients. They had all been patch tested with the standard test series supplemented with a textile dye mix (TDM) consisting of 8 disperse dyes, i.e. Disperse (D) Blue 35, 106 and 124, D Yellow 3, D Orange 1 and 3 and D Red 1 and 17. All but 3 of the TDM-positive patients were additionally tested with the separate dyes included in the mix. The frequency of contact allergy to TDM was 1.5%, which is comparable with studies from southern Europe. The most common dye allergen was D Orange 1. The high prevalence of allergic reactions to D Orange 1 was unexpected, whereas test reactions to D Blue 106 and 124 were lower than expected from other studies. Compared to all tested patients, the TDM-positive patients more often had dermatitis on their arms, face, neck and axillary folds, and women also had a higher frequency of hand dermatitis.

Diaper dye dermatitis

Diaper dermatitis is a common problem in outpatient pediatric office settings. Although most diaper rashes represent a form of contact dermatitis in response to irritants in the diaper environment, other rashes may be the result of an allergen in the diaper. On the basis of clinical examination results for 5 patients and patch testing results for 2 patients, we suspect that the patients demonstrated allergic contact dermatitis in response to the various blue, pink, and green dyes in diapers. Although topically administered corticosteroids are useful in the treatment regimen, the preferred treatment for allergic contact dermatitis in the diaper area is the use of dye-free diapers for allergen avoidance. Patch testing may also be valuable in identifying the allergen, because allergen avoidance is the key to prevention of recurrent disease.

Potency and risk assessment of a skin-sensitizing disperse dye using the local lymph node assay

Disperse Blue 106 is an acknowledged skin-sensitization hazard. However, information about the relative sensitization potency of this chemical is lacking, and to provide this information was the purpose of the investigations described here. The approach taken was to measure dose-response relationships for C.I. Disperse Blue in the local lymph node assay, a method for the assessment of skin-sensitization potential in which activity is measured as a function of lymphocyte proliferative responses induced in draining lymph nodes. From these data, it was possible to derive EC3 values (such being the estimated concentration of chemical required to elicit a 3-fold increase in proliferation) that have been shown previously to reflect the relative sensitizing potency of contact allergens. These analyses revealed that Disperse Blue 106 had a relatively low EC3 value (0.01%), comparable to that measured concurrently for 2,4-dinitrochlorobenzene, a potent contact allergen. Collectively, these data reveal that Disperse Blue 106 represents a significant skin-sensitization hazard, and, in combination with information on dye migration and percutaneous penetration from various types of fabric and use conditions provide a basis for the development of effective and accurate risk assessments.

Textile dermatitis in patients with contact sensitization in Israel: a 4-year prospective study

BACKGROUND

The exact incidence of textile dermatitis is unknown because of the lack of controlled epidemiological studies. Nevertheless, the increasing frequency of contact dermatitis to clothing has been demonstrated, thus indicating the importance of further investigations in this field.

OBJECTIVE

To analyse the results from a 4-year prospective study of the clinical and aetiological features of contact dermatitis to textiles in Israel. We also aimed to assess the frequency and relevance of sensitization to textile dyes and resins in these patients.

METHODS

Six hundred and forty-four patients (441 female and 203 male), referred for the investigation of contact dermatitis, and suspected of having textile allergic contact dermatitis (ACD), were studied. All patients were patch tested with the standard series (TRUE Tests), textile colour and finish series (TCFS) clothing extracts and pieces of garment in some cases. Readings were performed on days 2, 3 and in many patients also on day 7.

RESULTS

Eighty-three patients (12.9%) had an allergic reactions to a dye and/or resin allergen. Of them, 43 (51.8%) had positive patch tests to the textile dye allergens, 28 (33.7%) to the formaldehyde and textile finish resins and 12 (14.4%) to allergens from both groups. The highest incidence of sensitization from the dye group allergens was due to Disperse Blue (DB) 124 (30.6%), DB 106 (27.0%) and DB 85 (8.1%) and from the resin group to melamine formaldehyde and ethyleneurea melamine formaldehyde (20.7% each) and urea formaldehyde (18.3%). Present relevance of the patch tests was found in 81.4% of the cases. Concomitant sensitization with allergens from the standard series included nickel sulphate, potassium dichromate, formaldehyde, rubber additives and others. Although chronic dermatitis was the typical clinical presentation, less frequent forms such as purpuric, hyperpigmented and papulopustular lesions and atypical forms such as erythema multiforme-like, nummular-like lesions, lichenification and erythrodermia were observed in 24.4% of the cases. The atypical manifestations were provoked by sensitization to dye allergens and never to resins. Along with the typical distribution in areas of friction on the trunk and extremities, less frequent areas including the hands, face, genital area and the soles were affected too.

CONCLUSIONS

In view of the increasing frequency of contact dermatitis to clothing, the clinical assessment should include awareness of the classical as well as the unusual and atypical clinical forms and locations of ACD to textiles, for they are not infrequent. Although dyes and among them DB 106 and DB 124 are the most frequent allergens inducing textile dermatitis, concomitant testing with allergens from the textile dyes and resin groups is recommended when investigating patients with textile dermatitis.

Allergic contact dermatitis caused by the clothing dye, disperse blue 106, an important contact allergen that may be frequently missed

A 43-year-old woman presented with a history of dermatitis in a somewhat linear pattern under her breasts, across her back and around her waist. This dermatitis occurred after wearing a new blue dress with a blue lining. Patch testing showed an allergy to disperse blue 106 dye and also to her dress lining. However, she was not positive to p-phenylene-diamine, a dye in the standard patch test series. We recommend that any patient even slightly suspected of having an allergy to a textile dye should be tested with disperse blue, in addition to the standard series.

Foot dermatitis caused by the textile dye Basic Red 46 in acrylic blend socks

17 male subjects are described with foot dermatitis in association with positive patch test reactions to the textile dye Basic Red 46. Chromatographic analysis of the socks of 2 affected patients confirmed the presence of Basic Red 46. Withdrawal of the acrylic blend socks suspected of having been dyed with Basic Red 46 resulted in the improvement of symptoms in 12 of 17 patients (70.6%). However, equivocal or negative patch test results to their own socks were frequently noted in those patients. A highly significant association between the presence of foot dermatitis and a positive Basic Red 46 patch test reaction was noted in 555 patients from a patch test clinic population (P < 0.001). The prevalence of positive patch test reactions to Basic Red 46 was 1.2%. We suggest that patients with foot dermatitis be routinely patch tested for textile dyes. In particular, testing with Basic Red 46 should be considered in those with a history of use of dark-coloured acrylic and/or acrylic blend socks.

Contact sensitization to disperse dyes in children

From January 1996 to December 2000, 1098 children, including 667 subjects with suspected allergic contact dermatitis and 431 patients with atopic dermatitis (AD), were patch tested with seven disperse dyes: disperse blue 124 (DB124), disperse blue 106 (DB106), disperse red 1 (DR1), disperse yellow 3 (DY3), disperse orange 3 (DO3), p-aminoazobenzene (PAAB), and p-dimethylaminoazobenzene (PDAAB). Of these, 51 patients (4.6%; 34 girls and 17 boys) proved sensitized to disperse dyes. AD or history of AD was present in 30 patients (59%). The most common sensitizer was DY3 (17 patients), followed by DO3 (15 patients), and DB124 (14 patients). Among dye-positive patients, about 12% were sensitized to disperse dyes alone and only 14% reacted to para-phenylenediamine. In disperse dye-sensitive children not affected by AD, the feet, axillae, and groin appeared to be the most common localizations, whereas in those with AD, involvement of the face and the flexural areas of the limbs was more common. In conclusion, our study showed that in children with suspected contact sensitization, disperse dyes should be regarded as potential triggering allergens.

Is PPD a useful screening agent?

In this study, the usefulness was assessed of para-phenylenediamine (PPD) base as a marker for contact allergy to para-compounds and disperse dyes. 59 patients with a positive reaction to PPD were patch tested with a series of para compounds and disperse dyes. This dyes series was also tested in patients with a suspect medical history of contact allergy to hair, fabric or leather dyes. In total 610 patients were tested. As 24 patients became positive over the weekend, late readings, day 6 or 7, are important. These reactions were most probably relevant in 17/24 patients. Positive reactions to PPD correlated well with reactions to para compounds like p-aminoazobenzene and p-toluenediamine sulphate but not with disperse dyes. Reactions to Disperse Blue (106, 124) and Orange (1 and 3) were seen most frequently. PPD is a good screening agent for hair dye, but not for disperse dye, sensitivity.

Hand dermatitis as an unsuspected presentation of textile dye contact sensitivity

The aim of this study was to evaluate disperse dye sensitization in patients with hand dermatitis. From January 1996 to December 2000, we identified 130 patients with hand dermatitis reacting to one of the 7 dyes included in our standard series. In 82 subjects the dermatitis was localized to the hands alone, whereas 48 patients had lesions both on the hands and on other skin sites. Disperse Blue dyes, and Disperse Orange 3 were the most common sensitizers. Among the 13 subjects allergic to disperse dyes alone, we found 3 cases of occupational allergic contact dermatitis, 1 child with atopic dermatitis worsening after the use of synthetic fibre garments, 4 subjects affected by clothing dermatitis, and 5 individuals occupationally exposed to irritants with a dermatitis involving the hands alone. In the latter, the hands may represent a 'locus minoris resistentiae', and both induction and elicitation of contact sensitization could be caused by impaired barrier function at a skin site repeatedly exposed to sensitizing garments.

Pigmented purpuric contact dermatitis from Disperse Blue 106 and 124 dyes

The diagnosis of purpura pigmentosa progressiva in a female patient had to be changed to purpuric contact dermatitis after patch testing with textile dyes. A modified patch test performed in the area in which most of her skin lesions were located revealed a petechial reaction to the azo dye Disperse Blue 124/106. For evaluation of purpura pigmentosa progressiva we suggest a patch test with potential allergens, and, especially for textile dyes, a patch test at the lesion site may be helpful.

Contact allergy to Disperse Blue 106 and Disperse Blue 124 in German and Austrian patients, 1995 to 1999

Between 1995 and 1999, 1986 patients were tested in the 31 participating centres of the Information Network of Departments of Dermatology (IVDK), all of them members of the German Contact Dermatitis Research Group, with a textile dyes series containing Disperse Blue (DB) 106 and 124, and since 1997 also with a mix of both. 86 patients (4.3%) reacted positively to DB 106 and/or DB 124; with good concordance between the 2 allergens (Cohen's weighted kappa 0.72), and the single allergens and the mix (kappa=0.75 in both cases), which had been tested in parallel in 969 and 975 patients, respectively. In contrast, concordance between DB 106/124 and p-phenylenediamine and p-aminoazobenzene, respectively, was poor. Some 70% of positive reactions to DB 106/124 had current clinical relevance. Furthermore, a significant increase in the proportion of DB 106/124-positive patients among those tested was found from 1995 to 1999. Hence, DB 106/124 are important allergens deserving close monitoring. The use of a mix of DB 106 and DB 124 seems justified in view of the close chemical similarity of both compounds. If possible, the presence of the allergen(s) in individual textiles considered causative should be checked by thin layer or column chromatography.