Nine patients had allergic contact dermatitis to elastic materials in brassieres and one had the same reaction to a girdle. Three had classical rubber dermatitis, but the remainder were sensitive to spandex, a stretchable, synthetic fabric. Some of these patients also were contact sensitive to mercaptobenzothiazole (MBZ). Their spandex sensitivity presumably relates in most instances to the MBZ trace contamination of spandex in certain but not all brands. The patients could wear spandex brands that appeared to be uncontaminated with MBZ.
Joseph HL, Maibach HI. Contact Dermatitis From Spandex Brassieres. JAMA. 1967;201(11):880-882. doi:10.1001/jama.1967.03130110106036