Watch Out! Potential Allergic Contact Dermatitis to Acrylates in a Smart Watch

A 15-year-old girl with longstanding atopic dermatitis presented with eczema over the trunk, elbows, perioral skin (Figure 1) and left wrist (Figures 2a and 2b), at the exact site of her Apple smart watch. She was a competitive swimmer and gym user. Medications included tranexamic acid, topical steroids and emollients. Patch testing was performed to the British standard, medicaments, facial, oral and metals series (Chemotechnique Diagnostics, Sweden), using Finn chambers and Hypafix dressings (BSN Medical, Sweden). The acrylates series was added at Day 2. Readings performed on Day 2 and 4 according to ICDRG criteria, showed positive reactions to methylisothiazolinone (D2+/D4++), methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) (D2+/D4++), benzophenone-3 (D2-/D4+), benzophenone-4 (D2-/D4+), sodium benzoate (D2-/D4+), isobornyl acrylate (IBOA) (D2+), ethylene glycol dimethacrylate (D2+) and hexanediol diacrylate (D2+). Follow up 4 weeks later, revealed her skin had cleared having stopped drinking Vimto and Coca-cola which contained sodium benzoate, stopping her sunscreen and shower gel which contained MCI/MI, sodium benzoate and benzophenones, and having taken off her smart watch. Knowledge that acrylates are a common cause of allergic contact dermatitis (ACD) in diabetic devices [1] as well as Apple airpods [2], prompted us to test with the acrylate series. Our patient had no known previous acrylate exposure, in particular no history of using gel/acrylic nails. We have not been able to analyse the watch for acrylates but the Apple website [3] declares that their products may contain trace amounts of acrylates and nickel. There are two previous reported cases [4, 5] of Apple watch ACD, both attributed to nickel. In one case the dimethylglyoxime spot test on the watch was negative [4] and acrylate series not tested. In the other [5], 2-hydroxyethyl methacrylate was positive, however the full acrylate series was not tested. Our patient tested negative to nickel. A third case report [6] describes smart watch dermatitis in a 52-year-old lady; patch test negative to nickel but positive to methyl methacrylate and ethyl acrylate. Another interesting outcome in this case was her perioral dermatitis disappearing on removing sodium benzoate in the form of fizzy drinks. There is known reporting of both allergic contact dermatitis [7] as well as contact urticaria [8] to sodium benzoate in the literature. There are many reported cases of ‘irritancy’ caused by smart watches, however most have not been patch tested to the acrylate series. To our knowledge this is the first case suggesting possible acrylate ACD caused by an Apple smart watch. We encourage others to test with the acrylate series in similar future cases. Anna Davies: writing – original draft, data curation, resources. Natalie Stone: conceptualization, writing – review and editing, supervision. The authors declare no conflicts of interest.