Comment
Acrylates are used as adhesives to bond metal to plastic and as part of lithium ion polymer batteries, presumably similar to the one used in this device.5 Our patient had a history of using acrylic nail polish, which may have been a source of prior sensitization. Exposure to sweat or other moisture could theoretically dissolve such a water-soluble polymer,6 allowing for skin contact. Other acrylate polymers have been reported to break down slowly in contact with water, leading to contact sensitization to the monomer.7 The manufacturer of the device was contacted for additional information but declined to provide specific details regarding the device’s composition (personal communication, January 2014).
Although not considered toxic,8 acrylate was named Allergen of the Year in 2012 by the American Contact Dermatitis Society.9-11 Nickel might be a source of allergy for some other patients who wear mobile health devices, but we concluded that this particular patient developed allergic contact dermatitis from prolonged exposure to low levels of methyl methacrylate or another acrylate due to gradual breakdown of the acrylate polymer used in the rechargeable battery housing for this wearable health device.
Given the FDA’s tailored risk approach to regulation, many wearable sensors that may contain potential contact allergens such as nickel and acrylates do not fall under the FDA regulatory framework. This case should alert physicians to the lack of regulatory oversight for many mobile technologies. They should consider a screening history for contact allergens before recommending wearable sensors and broader testing for contact allergens should exposed patients develop reactions. Future wearable sensor materials and designs should minimize exposure to allergens given prolonged contact with continuous use. In the absence of regulation, manufacturers of these devices should consider due care testing prior to commercialization.
Acknowledgment
We are indebted to Alexander S. Rattner, PhD (State College, Pennsylvania), who provided his engineering expertise and insight during conversations with the authors.