Rubber Glove Dermatitis and Allergy to Dithiodimorpholine

To the Editor: We have recently patch tested 2 employees at our institution who developed hand dermatitis when the workplace replaced gray powder-free nitrile examination gloves with similar lavender ones from the same manufacturer. A 47-year-old female x-ray technician was referred from Employee Health for patch testing to evaluate hand dermatitis that began 2 months earlier. A few days after beginning to wear the new lavender gloves at work, she developed an itching and burning red rash over the tops of her hands and ulnar forearms. When she resumed use of the gray gloves, she had no symptoms. She performed a test wearing lavender on her left hand and gray on the right, resulting in symptoms and signs within hours on the left hand only. There was no history of prior allergies. Patch tests were performed using 3-panel Thin-Layer Rapid Use Epicutaneous test plus mercapto mix, carba mix, thiuram mix, mercaptobenzothiazole, mixed dialkyl thiourea, and dithiodimorpholine (DTDM) Chemotechnique (Vellinge, Sweden) allergens applied with Finn Chambers (Smart Practice, Phoenix, AZ). Her back showed a 2+ reaction at thimerosal and 2+ at DTDM at 48-hour removal (Fig. 1). At 96-hour reading, she had 1+ at quaternium-15, 2+ at thimerosal, 1+ at formaldehyde, trace at Bronopol, and 2+ at DTDM.Figure 1: Patch test at 48 hours in patient 1 shows positive for #66, DTDM.A 55-year-old male food service worker was referred from Employee Health for evaluation of hand dermatitis that flared 3 months earlier when he began to use the new lavender nitrile gloves. After clearing his eruption with desoximetasone ointment and resuming use of gray gloves, he remained free of problems. Patch testing was performed using Finn Chambers with the Chemotechnique North American Series-65 and 15 additional screening allergens including DTDM. At 48 hours, there was a 2+ reaction to DTDM. Two days later, all sites were negative except 2+ at methylchloroisothiazolinone/methylisothiazolinone, 2+ at propolis, and 2+ at DTDM (Fig. 2).Figure 2: Patch test sites at 96 hours in patient 2 show reactions to #25 methylchloroisothiazolinone/methylisothiazolinone, #61 propolis, and #66 DTDM.Both of our patients had symptoms temporally related to use of a particular nitrile glove and not triggered by any other exposures, including an alternative nitrile glove. The manufacturer, in response to our inquiry, stated that both glove types are primarily composed of acrylonitrile butadiene synthetic rubber, pigment, and inert ingredients. Both the gray and the lavender gloves are free of thiurams, but they may contain zinc carbamates, thiazole, or diphenyl guanidine as accelerators. Our patients did not show sensitivity to the usual rubber accelerator allergens, including the carbamates and thiazoles. Neither patient had known current exposure to the other allergens to which they tested positive. In the past, thiurams were cited as the most common sensitizers responsible for allergic contact dermatitis from rubber gloves.1 Geier and coworkers2 more recently reported, however, that mercaptobenzothiazole and carbamates have replaced thiurams as the most frequent accelerators used in rubber glove manufacture. Allergen replacement lists have been published to help guide glove selection to avoid these chemical families.3 The cases we report here suggest that perhaps DTDM is now coming into use in glove manufacture and may account for newer cases of occupational hand dermatitis from rubber gloves. Dithiodimorpholine is a vulcanizing agent used in the production of rubber tires and inner tubes as well as asphalt. When patients with foot dermatitis patch tested positive to DTDM, it was speculated they had been sensitized through rubber exposure in footwear, leading investigators to recommend addition of DTDM as a screening allergen in evaluating foot dermatitis.4 In a recent Mayo review of patch testing with rubber allergens, however, the majority of patients who tested positive to DTDM had hand (46.4%) rather than foot (10.7%) or generalized (25.0%) dermatitis.5 The authors acknowledged the potential for irritation from this allergen, but the reactions they observed conformed to the pattern of allergic patch test responses. They did not discuss possible sources of DTDM exposure in their hand dermatitis patients. In our patients, we would have failed to confirm the relationship of rubber accelerator allergy to occupational hand dermatitis had we not added DTDM to our screening series 2 years ago. With its use, we have observed the expected occasional early irritant reactions but also rare persisting or increasing pink papular responses characteristic of allergic response. It is difficult to discover exactly which chemicals may have been used during production of synthetic rubber gloves. Many manufacturers closely guard such data as proprietary. Furthermore, the manufacturing process undergoes frequent modification, and steps may be outsourced to factories in far-flung international sites, making accurate details unobtainable. Information from several product safety spokespersons for our manufacturer failed to include or specifically exclude DTDM as an accelerator used during the production of the lavender gloves. Our cases suggest that patch testing with DTDM may help identify allergy to rubber gloves in some patients with hand dermatitis who show no reaction to other commonly screened rubber accelerators. Future studies should investigate further the significance of this allergen in both hand and foot dermatitis. Dianne L. Silvestri, MD Division of Dermatology University of Massachusetts Medical Center Worcester, MA

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