Is BPA Hiding in Your Sports Bra? The New "Low-Tox" Standard

For years, the fitness industry has prioritized "performance" at any cost. That cost is now coming to light. Recent investigations by the Center for Environmental Health (CEH) have sent shockwaves through the wellness community, revealing that many popular sports bras and leggings contain high levels of Bisphenol A (BPA)—in some cases, up to 40 times the legal limit under certain safety standards. This discovery has ushered in a new "low-tox" standard for activewear, moving the conversation from general sustainability to immediate personal health.

Why is BPA in Activewear?

BPA is often associated with plastic water bottles and till receipts, but it is also used in the production of polyester and spandex to improve fabric performance and colorfastness. When you wear synthetic leggings or sports bras, your skin—the body’s largest organ—is in direct contact with these chemicals. During a workout, heat and sweat can further increase the rate at which these toxins are absorbed into the bloodstream. This raises a critical question for many: Are my gym clothes messing with my hormones?

As an endocrine disruptor, BPA mimics estrogen and can interfere with the body’s natural hormonal processes. For the high-performance athlete or the daily yoga practitioner, the cumulative exposure from hours spent in synthetic "plastic" clothing is becoming a major health concern.

The Rise of the "Low-Tox" Wardrobe

The "low-tox" movement is different from traditional eco-fashion. It isn't just about the planet; it’s about reducing the chemical load on the human body. This has led to a surge in demand for workout clothes without microplastics and hormone-disrupting chemicals. The primary solution lies in natural fibers, with Merino wool leading the charge.

Unlike polyester, which is essentially a petroleum product, Merino wool is naturally biodegradable, breathable, and free from the chemical additives required to make plastic fabrics perform. However, switching to a low-tox standard requires a nuanced understanding of fabric composition.

Performance Without the Toxins: The 95/5 Standard

While 100% organic materials are the goal for loungewear, high-intensity movement requires durability and recovery. For decades, the outdoor industry pushed 100% Merino as the "purest" option, but in an activewear context, 100% wool can lose its shape, sag when wet, or wear through quickly in high-friction areas.

To meet the low-tox standard while maintaining performance, the industry is shifting toward "core-spun" or high-percentage blends. A composition of 95% Merino wool and 5% elastane provides the necessary stretch and longevity without the toxic load of a fully synthetic garment. This slight blend ensures your gear lasts for years rather than months, reducing both chemical exposure and environmental waste. You can read more about why this balance is crucial in our guide: 100% Merino vs 95/5 Blends: Which Is Better for Activewear?

How to Audit Your Gym Bag

Transitioning to a low-tox activewear rotation doesn’t have to happen overnight. Start by replacing the items that have the most prolonged, intimate contact with your skin. Here is how to prioritize your transition:

Level 1 (Immediate): Sports bras and underwear. These sit closest to your lymph nodes and most absorbent skin areas.
Level 2 (High Sweat): Base layers and leggings. Replace polyester pieces that sit against your skin during heavy cardio sessions.
Level 3 (Outerwear): Jackets and hoodies. These are less critical for skin absorption but still contribute to microplastic shedding.

Restoring the Earth and Your Health

The fashion industry is at a crossroads. The dominance of polyester has not only led to a microplastic crisis in our oceans but a chemical crisis in our bodies. By choosing natural fibers like Merino wool, we are doing more than just buying a shirt; we are opting out of a system that treats toxic chemicals as a "standard" ingredient. Moving toward a low-tox, Merino-based wardrobe is a powerful step in restoring both the health of the individual and the health of the planet.