What chemicals are hiding in your activewear?

Conventional activewear is one of the most chemically intensive categories in your wardrobe. The base materials—typically polyester, nylon, and spandex blends—are petroleum-derived plastics that require heavy chemical processing to manufacture. On top of that, activewear frequently receives additional chemical treatments: PFAS for moisture wicking, antimicrobial agents like triclosan or silver nanoparticles for odor control, formaldehyde-based finishes for shape retention, and synthetic dyes that may contain heavy metals or azo compounds.

A 2023 investigation tested popular activewear brands and found PFAS, lead, and BPA at measurable levels in leggings, sports bras, and workout tops from major retailers. These findings are especially concerning given that activewear is worn during exercise—the exact conditions under which dermal absorption is at its highest. Tight fit, heavy sweat, elevated body temperature, and prolonged wear create a perfect storm for chemical transfer from fabric to body.

The safest activewear is made from certified natural fibers with minimal chemical processing. Reprise Activewear uses 100% Tencel with no synthetic additives. Wolven combines recycled materials with responsible chemistry. Vuori and Organic Basics offer OEKO-TEX certified options that ensure harmful substances stay below safe thresholds. At ONDU, our activewear curation prioritizes brands that are transparent about what goes into their fabrics, because what touches your skin during a workout matters more than most people realize.