Allergic contact dermatitis to accelerators in rubber gloves marketed as accelerator‐free

Abstract

Contact allergies to rubber accelerators used in the production of protective gloves, including thiurams, dithiocarbamates, benzothiazoles, and 1,3-diphenylguanidine are frequent in patients with work-related hand eczema, particularly in cleaning personnel, food handlers and healthcare workers.1, 2 To find suitable protective gloves for these individuals remains a challenge. Accelerator-free rubber gloves might be an alternative.2, 3 A 58-year-old female cleaner and kitchen help with a history of atopic dermatitis presented with hand eczema which reportedly had lasted already for 6 years. Patch tests were performed and read according to the guidelines of the German Contact Dermatitis Research Group (DKG)4 using the DKG baseline series as well as DKG ointment bases, preservatives, rubber, and disinfectants series as well as a sample of the disposable nitrile glove Purple Nitril-Xtra (Halyard Health) which had been used by the patient both at work and at home. A larger piece of the glove moistened with water was tested semi-open ‘as is’, covered with a tape without a chamber (Fixomull stretch, BSN Medical).5 Patch tests were removed on day (D) 2. At D3, positive reactions were found to potassium dichromate 0.5% pet (+), thiuram mix 1% pet. (+++), tetramethylthiuram monosulfide 0.25% pet. (++), tetraethylthiuram disulfide 0.25% pet. (++), and dipentamethylenethiuram disulfide 0.25% pet. (+) as well as a doubtful reaction (?+) to zinc diethyldithiocarbamate 1% pet. (all from SmartPractice Europe) (Figure 1A) and a marked and long-lasting positive reaction to the tested nitrile glove (+) which contains dithiocarbamates according to the manufacturer's information (Figure 1B). A partially work-related allergic contact dermatitis of the hands due to sensitization to rubber accelerators was diagnosed. Two disposable nitrile gloves marketed as accelerator-free medical gloves were selected for the patient to be used at home and at work. To our surprise, patch testing the patient with these gloves (as described above) led to a positive reaction (+) to SHIELDskin Orange Nitrile 300 (Shield Scientific) at D3 (Figure 1C). In a collaboration with the Institution for Statutory Accident Insurance and Prevention in the Healthcare and Welfare Services (BGW) and the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA), St. Augustin, Germany, a qualitative analysis using methyl tert-butylether extraction and sonication followed by gas chromatography and mass spectrometry (for details see supplement) at the IFA revealed that the analysed two different charges of the glove contained zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate and an unclassified benzothiazole derivate. A selection of six other disposable gloves produced by different manufacturers and all marketed as accelerator-free medical gloves were analysed by the same method. Rubber accelerators (zinc diethyldithiocarbamate and zinc dibutyldithiocarbamate) were only detected in one other glove (SHIELDskin Extreme Orange Nitrile 300) from the same manufacturer. Moreover, we confirmed the manufacturer's information that the glove Purple Nitril-Xtra (Halyard Health) which had been previously used by the patient, contained zinc diethyldithiocarbamate. The patient was finally equipped with a second protective glove made of polyvinyl chloride. Rubber accelerators are widely used in the production of natural and synthetic rubber gloves. Nowadays, thiurams have mostly been replaced by dithiocarbamates for this purpose.6, 7 However, thiurams and dithiocarbamates constitute a redox pair and are transformed into each other and thiurams are considered a better marker for a thiuram/dithiocarbamate sensitisation when patch tested.6 Therefore, individuals with sensitization to thiurams are advised to also avoid dithiocarbamates.3 In response to contact allergies to rubber accelerators, glove manufacturers have developed and marketed accelerator-free gloves.2 According to European standard EN 455-3, which is mainly used for medical gloves, the absence of a substance may only be declared by the manufacturer if the substance is not used in any part of the manufacturing process. Despite being marketed as accelerator-free, classified as medical device and labelled with EN 455-3, the analysis revealed that the selected ‘accelerator-free’ glove SHIELDskin Orange Nitrile 300 contained three accelerators of which two were dithiocarbamates, explaining the positive patch test reaction to the glove in our patient. Reassuringly, common accelerators were undetectable with the same analytic methods in all but one of the other analysed gloves marketed as accelerator-free medical gloves. Notably, the only other accelerator-containing glove was produced by the same manufacturer. Upon request, the manufacturer informed us that the gloves are not supposed to contain any thiurams or dithiocarbamates, but cross-contamination could not be excluded as the same manufacturing facilities are used for the production of accelerator-free and accelerator-containing gloves. We here show that protective gloves classified as medical device and marketed as accelerator-free are not necessarily free of accelerators. As a qualitative and not a quantitative analysis was performed, we cannot comment on the amounts of the detected accelerators. Even if the ‘accelerator-free’ glove contains much smaller amounts of accelerators than conventional rubber gloves, this might still cause allergic contact dermatitis in individuals with strong sensitizations to rubber accelerators. Patch testing these gloves prior to use may help to assess individual tolerability even though this cannot exclude development of allergic contact dermatitis upon wearing. Correct labelling of glove ingredients and tight surveillance of the production process are warranted. Richard Brans: Conceptualization; investigation; writing – original draft; methodology; writing – review and editing; project administration; data curation. Silke Werner: Conceptualization; investigation; writing – original draft; writing – review and editing; methodology; validation; project administration; data curation. Lara Obermeyer: Investigation; writing – review and editing. Andreas Hansen: Investigation; writing – review and editing. Christiane Altenburg: Conceptualization; investigation; funding acquisition; writing – review and editing; methodology; project administration. Albert Nienhaus: Conceptualization; writing – review and editing; methodology; funding acquisition; investigation. There are no conflicts of interest. Data S1: Supporting Information Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

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