Athletic shoe dermatitis. Contact allergy to ethyl butyl thiourea

Ten patients with severe foot dermatitis were found to be highly allergic to innersole material prepared by Spenco Medical Corporation and used in Nike athletic shoes. Contact allergy testing showed sensitivity to ethyl butyl thiourea, a chemical accelerator in some neoprene (polychioroprene) rubber products. The dermatitis was recalcitrant and in many cases persisted long after discontinuance of wearing Nike shoes, raising the concern that traces of ethyl butyl thiorea or cross-reacting chemicals may be present in other footwear.