Synthetic activewear breaks down during wear and washing, releasing microplastic fibers that can transfer toxic chemicals like PFAS (per- and polyfluoroalkyl substances, also called "forever chemicals") and BPA (bisphenol A) directly into your skin through sweat. A landmark 2023 study from the University of Birmingham found that brominated flame retardants in microplastics leach into the hydrolipidic film, the natural oils and moisture on your skin surface, making these toxins available for your body to absorb during physical activity.

What Chemicals Are Actually in Your Activewear?

The chemical contamination in synthetic workout clothes is more widespread than many athletes realize. In 2022, the Center for Environmental Health (CEH), a nonprofit research organization, identified significant levels of BPA in sports bras, performance shirts, and polyester-spandex clothing from major brands. The organization found that wearers could be exposed to levels up to 40 times the safe limit according to California law. This discovery prompted legal notices sent to retailers and manufacturers including Athleta, Champion, Kohl's, Nike, and Patagonia.

Beyond chemical additives, the microplastic shedding problem is staggering in scale. A 2016 study published in the Marine Pollution Bulletin found that a single 6-kilogram wash load of acrylic or polyester fabric could shed over 700,000 microplastic fibers. These aren't inert particles; they're carriers of toxic compounds.

How Do Microplastics From Activewear Enter Your Body?

The pathway for chemical exposure happens in two ways. First, during wear, sweat triggers chemical leaching from microplastics deposited on your skin surface. The University of Birmingham researchers were the first to prove that toxic chemicals can transfer from microplastics into sweat and skin oils, meaning they're available for absorption through your skin. Second, during washing, the physical shedding of plastic fibers contributes to environmental pollution and may lead to indirect human exposure through contaminated water, food, and air.

Approximately 92 million tonnes of textile waste is produced annually, with synthetic fibers accounting for 60 percent of global apparel purchases. These synthetic materials, primarily polyester and nylon, are made from fossil fuels such as petroleum and can take hundreds of years to biodegrade. Their production releases greenhouse gases, and the microplastics they shed accumulate in waterways, oceans, and soil.

What Natural Fiber Alternatives Reduce Chemical Exposure?

The good news is that natural and innovative sustainable fibers exist as alternatives to synthetic activewear. These materials don't shed microplastics and avoid the chemical additives found in conventional polyester and nylon blends. Choosing activewear made from plant-based or animal-derived fibers helps reduce your exposure to PFAS, BPA, and other synthetic textile additives while minimizing your carbon footprint.

• Organic Cotton: GOTS-certified organic cotton is grown without synthetic pesticides and fertilizers, making it a clean alternative for everyday wear and light workouts. It's breathable, soft on skin, and biodegradable.
• Alpaca or Merino Wool: These natural fibers naturally wick moisture, are naturally antibacterial, dry quickly, and resist body odor. Alpaca wool's semi-hollow fibers act as natural temperature regulation, balancing your body temperature to the outside climate.
• Hemp: A durable, sustainable plant fiber that requires minimal pesticides to grow and offers excellent breathability for active wear.
• TENCEL Lyocell or Modal: These are regenerated cellulose fibers made from sustainably sourced wood pulp using closed-loop production processes that minimize chemical waste and water pollution.

Some natural fiber leggings include a small percentage of recycled elastane, up to 14 percent, which is necessary to provide stretch and recovery in the fabric. This minimal synthetic content is significantly lower than conventional activewear, which typically contains 15 to 30 percent spandex or elastane.

How to Choose Activewear That Minimizes Chemical Exposure

• Check Fiber Content: Look for activewear made primarily from organic cotton, hemp, alpaca wool, merino wool, or TENCEL Lyocell. Avoid polyester, nylon, and acrylic unless they're recycled and certified by third-party standards.
• Verify Certifications: Seek out GOTS (Global Organic Textile Standard) certification for organic cotton, OEKO-TEX certification for dyes and finishes, and Fair Trade Certified labels that ensure ethical production practices.
• Research Dye Methods: Ask whether brands use plant-based or natural dyes rather than synthetic chemical dyes. Some manufacturers use vegetable-based dyes or OEKO-TEX certified dyes that minimize chemical exposure.
• Examine Transparency: Choose brands that openly disclose their material sourcing, production locations, and chemical treatments. Brands that hide their supply chain or use vague marketing terms like "eco-friendly" without certification are less trustworthy.
• Consider Durability: Higher-quality natural fiber activewear lasts longer, reducing the need for frequent replacement and the overall environmental impact of your wardrobe.

The shift toward cleaner activewear reflects growing consumer awareness of the hidden health costs of synthetic clothing. As research continues to document the chemical risks associated with polyester and nylon activewear, more athletes are reconsidering their gear choices. The evidence is clear: what you wear during exercise matters not just for performance, but for your long-term health and the health of the environment.