You wouldn't slather your skin with toxic lotion, but what about the leggings you wear every day? Activewear is our second skin, so it's time to take a closer look at what it's made of.
The truth? Many mainstream leggings and sports bras contain hidden chemicals treatments that have been linked to hormone disruption, skin irritation, and long-term health concerns.
Not all leggings are created equal, and some are even quietly and continuously exposing you to harmful chemicals. Here is what you need to know.
The Hidden Chemicals Lurking in Activewear
Many conventional leggings are treated with or made from synthetic chemicals that help improve stretch, colorfastness, sweat-wicking, or odor resistance, but these can come at a cost. Let’s break down some of the biggest offenders.
BPA (Bisphenol A):
What it is: A synthetic compound used to harden plastics. Its commonly used to make plastics like polycarbonate and epoxy resins. NOTE:I t’s important to note here that BPA is not, and never has been, used to make PET, the type of plastic found in polyester. It is, however, often used as a chemical finish in polyester and nylon fabrics
Why it’s used in fashion: BPA is often added to fabrics for enhancements in durability and color retention.
Why it matters: BPA is an endocrine disruptor- meaning it can interfere with your hormone function. It mimics estrogen and may contribute to hormone imbalances, fertility issues, metabolic disfunction, and even certain cancers.
PFAS ("Forever Chemicals"):
What they are: A class of over 12,000 chemicals that don’t break down in the environment (due to their very strong carbon-flourine bond). They are used in a wide range of everyday products, from nonstick cookware to firefighting foams, and yes, even your favorite leggings.
Why they are used in fashion: They are often applied to make leggings sweat proof, quick drying, or stain resistant.
Why it matters: PFAS have been linked to thyroid dysfunction, developmental toxicity, and immune surpression. Worse- just like in the environment, they don’t break down in your body. That’s why we call them “forever chemicals”.
Formaldehyde:
What it is: A colorless (and flammable) gas that, just like PFAS, are used in a large range of products:
Why its used: It is often used to prevent shrinkage, mildew, and wrinkles.
Why it matters: The International Agency for Research on Cancer (IARC – FIND CITATION) classifies formaldehyde as a Group 1 carcinogen – meaning there is sufficient evidence it causes cancer in humans.
AZO Dyes:
What it is: cost effective, synthetic dyes commonly used in the fashion industry
Why they are used: For vibrant colors
Why it matters: Some AZO dyes break down into aromatic amines, compounds linked to bladder cancer and skin sensitization. The US has banned over 20 types of AZO dyes in textiles that come into contact with skin – but they are still used widely in the US
Phthalates:
What they are: A group of chemicals used to make plastics more flexible
Why they are used in fashion: they are often found in logos, screen prints, and stretch coatings to, you guessed it, make them more flexible.
Why it matters: Pthalates are another group of endocrine disruptors, affecting reproductive development, especially in adolescents and pregnant women.
Why Leggings Pose a Unique Risk
You may be thinking “I’m surrounded by chemicals every day – and it sounds like a lot of these are in a lot of things besides my clothing – why worry about my leggings?
Here is why they deserve special attention:
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Skin-tight contact & long wear time = increased dermal absorption
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Sweat increases fabric break down, due to its microscopic abrasive properties. Just think about how salt is often used to clean!
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Heat and friction can cause chemicals to leach out of the fabric faster
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Repetitive use of the things you use every day like sleepwear, workouts, or even just daily wear, makes exposure cumulative.
In short, what you wear against your body every day has a much bigger impact than you may think!
Bonus science fact: According to the CDC, transdermal absorption accounts for up to 10% of total chemical exposure for some environmental toxins—especially in areas of the body with high blood flow or thin skin (like underarms, groin, and abdomen).
How to Identify Non-Toxic Activewear
Look for certifications:
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Oeko-tex standard 100: tests finished fabrics for substances harmful to human health
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GOTS (for organic cotton) requires non-toxic dying and finishing practices
Avoid these red flags
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“stain resistant” or “moisture-wicking” with no ingredient list
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Vague marketing terms like “eco-friendly” or “natural feel” with no transparency
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Brightly dyed items with strong chemical or vinegar-like odors
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Screen prints or rubber logos that feel plasticky or stiff
Bottom Line: You Deserve Better
Clean activewear isn’t optional, it's essential. The clean beauty movement taught us to question what we put on our skin. It’s time to do the same with what we wear.
When it comes to leggings, one of the most worn and most intimate pieces in your wardrobe, it's worth asking the tough questions. Are they safe? Are they supporting your health - or compromising it?
At Losano, we believe you shouldn’t have to choose between performance and purity. You can have both!
