Assessment of Contact Allergens in ‘‘Hypoallergenic’’ Athletic Shoes by Mass Spectrometry

Background: Identification of athletic shoes for patients with contact allergy is difficult. Company reports of allergen content are often incorrect. Objectives: To determine whether chemical analysis of 4 athletic shoes, previously reported to be free of the most common contact allergens, contain quantifiable allergen levels. Methods: Samples from the uppers and insoles of 4 shoes believed to be free of common allergens were assessed by mass spectrometry. A total of 4 rubber accelerators and 2 adhesives were directly quantified and additional 7 rubber accelerators were assessed using semiquantitative measures. Results: Aside from carbamates (assayed as 59 ppm zinc in insoles) in SeaVee’s Sixty-Six sneakers, paratertiarybutylphenol formaldehyde resin (PTBFR) (assayed as 7.6 ppm paratertiary butylphenol or 4-tertiary butylphenol [4TBP] in uppers) in Allbirds Tree Runners and rosin (assayed as 628 ppm sodium abietate in uppers) and carbamates (24 ppm zinc in uppers) in Saucony Jazz sneakers, these shoes had low levels of all allergens assayed in this study. Tom’s Carlo sneakers contained rosin (127 ppm sodium abietate in insoles), PTBFR (6.5 ppm 4TBP in uppers), and carbamates (112 ppm sodium abietate in insoles) but had low levels of all other assayed allergens. Conclusions: Although identifying allergen-free shoes is challenging, the results of this analysis will help patch testing physicians recommend athletic shoes to patients with specific allergies.