Occupational Allergic Contact Dermatitis Caused by Mercaptobenzothiazole in DS2 Dust Mask Straps During the COVID-19 Pandemic: A Study of Outbreak and Proposal of Safer Alternatives

Background: The global COVID-19 pandemic has necessitated the widespread use of dust masks, including N95 and DS2, in healthcare settings. Although allergic contact dermatitis caused by dust mask straps has been reported, component analysis of the straps is rare. We encountered an outbreak of dermatitis cases due to rubber straps of a DS2 mask (Mask A) at our hospital. Objectives: To investigate the cause of dermatitis associated with Mask A rubber strap, identify the allergens responsible for allergic contact dermatitis and propose suitable alternative masks. Patients/Methods: Twelve healthcare workers who developed contact dermatitis after wearing Mask A were enrolled. A detailed questionnaire, chemical analyses of Mask A rubber straps and alternatives and patch testing with identified components of the straps were performed. Results: Twelve cases (nine females, three males; mean age 47.8 ± 11.1 years) had no prior history of contact rubber allergy. The straps of Mask A contained thiazole-type vulcanisation accelerators and degradation products. Patch testing revealed sensitisation to 2-mercaptobenzothiazole, 2,2′-dithiobis(benzothiazole) and 2-(methylthio)benzothiazole in eight, three and five cases, respectively. Conclusion: Occupational allergic contact dermatitis due to 2-mercaptobenzothiazole in Mask A straps was diagnosed in eight cases. All affected individuals successfully switched to alternative masks without recurrence.