The preservative 2‐(thiocyanomethylthio)benzothiazole: A potential allergen in leather products

Allergic contact dermatitis to footwear in Thailand: Prevalence, clinical characteristics and common allergens

BACKGROUND

Footwear contact allergy is caused by exposure to allergens in shoes. The prevalence and common allergens vary by region and time due to differences in customs and lifestyle.

OBJECTIVES

To determine the clinical characteristics and common allergens of patients with footwear-related allergic contact dermatitis (ACD) who attended Siriraj Hospital in Bangkok, Thailand, between 2001 and 2020.

METHODS

The medical records of 247 patients with clinically suspected footwear dermatitis who underwent patch testing were reviewed.

RESULTS

The prevalence of ACD to footwear was 1.8%. Females were predominant (71.6%). The three most common allergens were carba mix (7.7%), mercapto mix (6.9%) and potassium dichromate (6.9%). According to the allergens found, rubber (14.2%), adhesives (7.7%) and leathers (6.9%) were the three most common groups. Dorsal-limited skin lesions were significantly associated with footwear ACD.

CONCLUSION

Rubber and leather allergens were still the most common culprit allergens. Dermatologists should keep up-to-date on common allergens in footwear and emerging allergens to include in patch test series.

Sofa dermatitis: Value of patch test with 2-(thiocyanomethylthio)benzothiazole

BACKGROUND

In 2008, numerous cases of allergic contact dermatitis caused by leather chairs (sofa dermatitis) were reported, with dimethylfumarate being the culprit allergen. However, octylisothiazolinone, methylisothiazolinone and cobalt have also been associated with cases of sofa dermatitis. An antifungal agent, 2-(thiocyanomethylthio)benzothiazole (TCMTB), has also previously been described as a contact allergen in leather.

MATERIALS AND METHODS

Seven patients were referred to the Department of Dermatology of the Cliniques universitaires Saint-Luc, Brussels, Belgium with suspicion of allergic contact dermatitis caused by leather sofas. They were patch tested with the European Baseline Series, additional series (according to the patients' history and clinical aspect of the eruption), dimethylfumarate (4/7 patients) and with TCMTB.

RESULTS

All seven patients presented a positive reaction to TCMTB and only one presented a concomitant positive reaction to dimethylfumarate. All patients showed clinical improvement after avoiding contact with their leather sofa.

CONCLUSION

2-(Thiocyanomethylthio)benzothiazole (TCMTB) is probably an underestimated allergen present in leather chairs (responsible for the so-called 'sofa dermatitis'), and more generally in leather objects. It is, therefore, important to test with TCMTB 0.1% petrolatum in case of contact dermatitis related with leather products.

Shoe Allergens: A Retrospective Analysis of Cross-sectional Data From the North American Contact Dermatitis Group, 2005-2018

BACKGROUND

Shoe contact allergy can be difficult to diagnose and manage.

OBJECTIVE

The aim of the study was to characterize demographics, clinical characteristics, patch test results, and occupational data for the North American Contact Dermatitis Group patients with shoe contact allergy.

METHODS

This is a retrospective study of 33,661 patients, patch tested from 2005 to 2018, with a shoe source, foot as 1 of 3 sites of dermatitis, and final primary diagnosis of allergic contact dermatitis.

RESULTS

Three hundred fifty-two patients met the inclusion criteria. They were more likely to be male (odds ratio = 3.36, confidence interval = 2.71-4.17) and less likely to be older than 40 years (odds ratio = 0.49, confidence interval = 0.40-0.61) compared with others with positive patch test reactions. The most common relevant North American Contact Dermatitis Group screening allergens were potassium dichromate (29.8%), p-tert-butylphenol formaldehyde resin (20.1%), thiuram mix (13.3%), mixed dialkyl thioureas (12.6%), and carba mix (12%). A total of 29.8% (105/352) had positive patch test reactions to supplemental allergens, and 12.2% (43/352) only had reactions to supplemental allergens.

CONCLUSIONS

Shoe contact allergy was more common in younger and male patients. Potassium dichromate and p-tert-butylphenol formaldehyde resin were the top shoe allergens. Testing supplemental allergens, personal care products, and shoe components should be part of a comprehensive evaluation of suspected shoe contact allergy.

Patch test results in patients with suspected contact allergy to shoes: Retrospective IVDK data analysis 2009-2018

BACKGROUND

Allergic contact dermatitis caused by shoes is common and new relevant allergens have been identified.

OBJECTIVES

To investigate the pattern of type IV sensitization in patients with suspected allergic contact dermatitis of the feet related to shoes as a presumed culprit trigger.

METHODS

Retrospective analysis of data of the Information Network of Departments of Dermatology (IVDK), 2009-2018.

RESULTS

Six hundred twenty-five patients with presumed shoe dermatitis were identified in a cohort of 119 417 patients. Compared to patients with suspected contact sensitization from other allergen sources (n = 118 792), study group patients were more frequently sensitized to potassium dichromate (10.8% vs 3.5%), colophony (7.2% vs 3.7%), mercaptobenzothiazole (MBT; 4.0% vs 0.6%), mercapto mix (4.6% vs 0.6%), and p-tert-butylphenol formaldehyde resin (1.6% vs 0.5%). Sensitizations to urea formaldehyde resin, melamine formaldehyde resin, glutaraldehyde, tricresyl phosphate, and phenyl glycidylether were rare. Moreover, reactions to compounds in the leather or textile dyes test series were scarce.

CONCLUSION

A distinct sensitization pattern was observed in patients with suspected allergy to shoe materials. Although substances with low sensitization rates should be removed from the leather and shoe patch test series, novel potential allergens should be added.

Patch Testing of Mercaptobenzothiazole and Mercapto Mix: The North American Contact Dermatitis Group Experience, 1994-2016

OBJECTIVES

Mercapto compounds are a category of rubber accelerators that may cause allergic contact dermatitis. This study characterizes patch test reactions to mercaptobenzothiazole (MBT) and mercapto mix (MM) in a large North American population.

METHODS

The 1994-2016 North American Contact Dermatitis Group screening series data were analyzed. Patients with allergic reactions to either MBT or MM (mercapto+) were included. The following characteristics were analyzed: strength of reaction, clinical and occupational relevance, coreactivity with other rubber accelerators, and sources of exposure.

RESULTS

A total of 49,795 patients were tested to mercapto compounds from 1994 to 2016; 633 (1.3%) had positive reactions to MBT and/or MM. The frequency to both MBT and MM significantly decreased over time (P < 0.0001). Mercapto+ patients were significantly more likely to be male, have occupationally related skin disease, and report involvement of the hands and/or feet (P < 0.0001). They were significantly less likely to have face, scalp/ears/neck, or trunk involvement (P ≤ 0.0001). There was significant coreactivity with carba mix (23.4%) and thiuram mix (32.5%). Mercaptobenzothiazole and MM reactions were frequently clinically (81.7% and 83.5%, respectively) and occupationally relevant (29.8% and 33.4%, respectively). Gloves were the most common source (31.3% and 30.9%, respectively).

CONCLUSIONS

Patch test positivity to mercapto compounds significantly decreased from 1994 to 2016 but remains clinically and occupationally relevant.

Allergic contact dermatitis: From pathophysiology to development of new preventive strategies

As the body's first line of defense, the skin is the organ most frequently exposed to chemicals present in personal hygiene products, household products, or materials used in the work environment. In this context, skin disorders account for more than 40 % of all occupational and work-related diseases, constituting a significant public health burden. Among skin disorders, allergic contact dermatitis (ACD) is the most prevalent occupational disease and the most common form of immunotoxicity in humans. ACD is a T-cell-mediated skin inflammation resulting from the priming and expansion of allergen-specific CD4⁺ and CD8⁺ T cells. The clinical condition is characterized by local skin rash, itchiness, redness, swelling, and lesions, being mainly diagnosed by the patch test. Upon ACD diagnosis, avoiding the exposure to the triggering allergen is the mainstay of treatment to prevent future flares. In cases where avoidance is not possible, the use of a standard of care interim treatments such as steroid creams or ointments, barrier creams, and moisturizers are strongly recommended to alleviate symptoms. In this review, we sought to provide the reader with an overview of the pathophysiology of ACD as well as the currently available pharmacological treatment options. Furthermore, a comprehensive outline of several preventive strategies is also provided.

Contact Allergy-Emerging Allergens and Public Health Impact

Contact allergy (sensitisation) and allergic contact dermatitis (ACD) resulting from it have a considerable public health impact. For the present review, all pertinent articles were systematically searched via Medline and Web of Science™; additionally, all available issues of the journals "Contact Dermatitis" and "Dermatitis" were manually searched, covering the years 2018-2019, thereby extending and re-focusing a previous similar review. New allergens, or previously described allergens found in a new exposure context or of other current importance, are described in sections according to substance classes, e.g., metals, preservatives, fragrances. As a common finding in many investigations, a lack of information on product composition has been noted, for instance, regarding a newly described allergen in canvas shoes (dimethylthiocarbamylbenzothiazole sulfide) and, most notably, absence of co-operation from manufacturers of glucose-monitoring devices and insulin pumps, respectively. These latter devices have been shown to cause severe ACD in a considerable number of diabetic patients caused by the liberation of isobornyl acrylate and N,N'-dimethylacrylamide, respectively, as demonstrated by an international collaboration between dermatologists and chemists. Improved and complete ingredient labelling for all types of products, and not just cosmetics, must be put on the legislative agenda.