Reading an activewear label like a chemist: what the fiber content doesn't tell you

The label tells you fiber. It doesn't tell you chemistry.

Pick up any pair of leggings or sports bra. Flip to the care label. You'll see something like: 78% Nylon, 22% Elastane.

That's fiber content. It's legally required. It's also nearly useless for understanding what chemicals are actually present in the finished garment.

The fiber itself is only part of the story. The rest happens in the dye house, the finishing line, and the coating application. That's where PFAS gets added for water repellency. That's where BPA enters the supply chain as a plasticizer in spandex. That's where antimicrobial silver gets embedded for odor control.

None of that appears on the label. And for activewear founders sourcing product, that gap between what's disclosed and what's actually present is becoming a legal, reputational, and biological liability.

What's actually in conventional activewear

Let's start with the compounds that have been detected in independent testing of major activewear brands.

PFAS (per- and polyfluoroalkyl substances)

Testing by Mamavation and Environmental Health News found detectable levels of fluorine, a marker for PFAS, in one out of every four pairs of leggings and yoga pants they tested. Brands with positive results included names many families shop regularly: Old Navy and Lululemon were both among those flagged. The levels ranged from 10 to 284 parts per million.

PFAS are added to activewear for durable water repellency (DWR). In activewear, PFAS typically appear as durable water repellent coatings on outer shells, or as internal fluorine-based finishes on moisture-wicking fabrics. Durable-water-repellent garments contain approximately three times higher PFAS concentrations than conventional functional items.

The regulatory pressure is real. Multiple bans took effect in January 2026, with more on the way. California AB 1817 bans intentionally added PFAS in textiles, effective January 2025. Outdoor apparel for severe wet conditions must carry a "Made with PFAS chemicals" disclosure label. The total organic fluorine threshold drops from 100 ppm to 50 ppm in January 2027.

The Texas attorney general is investigating Lululemon for PFAS. The U.S. activewear market generated $137.4 million in revenue last year, and it can seem like everyone in the country now wears workout clothes for both exercise and everyday activities. So recent news that leading activewear brand Lululemon is being investigated by Texas Attorney General Ken Paxton over the potential presence of "forever chemicals" may concern anyone who puts on leggings multiple times a week.

BPA (bisphenol A)

The Center for Environmental Health sent legal notices to eight additional brands whose leggings, shorts, sports bras, and athletic shirts after testing showed the clothing could expose individuals to up to 40 times the safe limit of the chemical bisphenol A (BPA), according to California law.

The new brands include leggings from Athleta, Champion, Kohl's, Nike, Patagonia, sports bras from Sweaty Betty, athletic shirts from Fabletics, and shorts from Adidas, Champion, Nike.

BPA, a well-studied hormone disrupting chemical, mimics estrogen and can disrupt the normal functioning of the body, including metabolism, growth and development, and reproduction.

The absorption mechanism matters here. Sweat dramatically amplifies dermal absorption, up to 3,252-fold compared to dry contact, making workout exposure especially significant.

The problem with the label

The fiber content disclosure tells you whether the garment is nylon or polyester. It doesn't tell you:

• Whether the fabric has been treated with a fluorinated DWR finish
• Whether BPA was used as a plasticizer in the spandex component
• Whether antimicrobial silver has been embedded in the fibers
• Whether the dyes contain azo compounds that release carcinogenic amines
• Whether formaldehyde-based resins were used for wrinkle resistance

For a founder building an activewear brand, this means you cannot rely on your factory's standard spec sheet. You need to ask different questions.

What founders should actually spec

1. Request a Restricted Substances List (RSL) declaration

Any reputable factory should be able to provide documentation showing compliance with major RSLs. The AFIRM RSL is increasingly becoming the baseline for buyer approval. For many brands, AFIRM compliance is now the starting point for supplier approval.

But an RSL declaration is not the same as third-party testing. It's a statement of intent. You need the test reports.

2. Require OEKO-TEX Standard 100 certification

OEKO-TEX Standard 100 tests the finished garment for 1,000+ harmful substances, including BPA, PFAS, azo dyes, and formaldehyde.

This is the most practical certification for activewear founders because it tests the final product, not just individual inputs. A fabric might be sourced from a certified mill, but if the finishing house adds a non-compliant treatment, the final garment fails.

3. Specify "no intentionally added PFAS"

This language matters. Compared with previous rules, the new regulation removes several exemptions and places stronger restrictions on intentionally added PFAS. Only unavoidable trace contamination is tolerated. This means suppliers must be much more confident about their chemical inputs and production controls.

If your factory cannot provide documentation confirming no intentionally added PFAS, you have a compliance gap. California, New York, and multiple other states now have textile PFAS restrictions in force.

4. Ask about the spandex source

BPA has been found specifically in polyester-based clothing with spandex. The Center for Environmental Health has found BPA in polyester-based clothing with spandex, including sports bras and athletic shirts. BPA may be introduced during textile production, dyeing, finishing, or other chemical treatment stages.

Not all spandex is equivalent. Some manufacturers use bio-based elastane alternatives that avoid petroleum-derived plasticizers entirely. This is where fiber selection actually does matter, but you have to ask the specific question.

The Los Angeles supply chain reality

For founders sourcing locally, the Los Angeles garment district presents both advantages and challenges for chemical transparency.

The Los Angeles garment district remains a historic hub for rapid prototyping, streetwear innovation, and the coveted "Made in USA" label.

The advantage: proximity. You can walk into a factory, ask to see their chemical input documentation, and inspect their finishing processes directly. When manufacturers are local, designers can pop in during production runs, catch issues before they become problems, and make adjustments on the fly.

The challenge: fragmentation. Unlike vertical international factories, clothing manufacturers in Los Angeles often require you to source your own fabric, buy your own zippers, and transport materials from a dye house to a cut-and-sew facility.

This fragmentation means the chemical chain of custody becomes harder to track. Your fabric might come from one supplier, go to a separate dye house, then to a finishing facility, then to your cut-and-sew partner. At each handoff, you lose visibility into what's being applied.

A worked example

Imagine a Los Angeles-based activewear founder, let's call her Maya, who's launching a legging line. She sources her nylon-spandex fabric from a well-known LA fabric supplier in the Fashion District. The fabric feels great. The stretch is right. The opacity passes her squat test.

But she never asks whether the fabric has been treated with a DWR finish. She doesn't request OEKO-TEX documentation. She doesn't specify "no intentionally added PFAS" in her purchase order.

Six months later, California's 50 ppm threshold takes effect. A competitor sends her product to a testing lab. The results come back at 180 ppm total organic fluorine.

Maya now has inventory she cannot legally sell in her home state. The reputational damage spreads faster than she can issue a recall.

This is not a hypothetical. It's the scenario playing out across the activewear industry right now.

The trade show opportunity

As part of Messe Frankfurt's global trade fair portfolio, Apparel Sourcing Los Angeles is regionally rooted and globally connected. Its venue in Downtown Los Angeles offers an ideal setting, thanks to its central location, modern infrastructure, and proximity to important industry networks. More than just a fashion trade show, Apparel Sourcing Los Angeles is a meeting point for forward-thinking brands, designers, and manufacturers seeking market-ready collections and sustainable production solutions.

The 2026 edition of Apparel Sourcing Los Angeles will be held at California Market Center starting on 21st July. The event features insightful seminars and workshops, offering critical insights into textile trends and sustainable solutions. Participants can discover innovations in high-tech textiles and eco-friendly materials that are redefining the fashion industry.

If you're sourcing activewear and attending shows like this, your first question to any fabric supplier should be: "Can you provide OEKO-TEX Standard 100 certification for the finished fabric, and can you confirm no intentionally added PFAS?"

If the answer is no, or vague, you have your answer.

The certifications that actually matter

Not all certifications are equivalent for chemical safety. Here's what to prioritize:

OEKO-TEX Standard 100: Tests the finished product for harmful substances. This is your baseline.

Bluesign: For brands using recycled fabrics, Bluesign certifies safer chemistry in processing and requires PFAS-free production from January 2025.

GOTS (Global Organic Textile Standard): GOTS covers organic fibre sourcing and prohibits harmful chemicals throughout the full supply chain. This is strongest for natural fiber products but less applicable to performance synthetics.

GOTS + OEKO-TEX together is the gold standard for chemical transparency in textiles.

What doesn't help: vague claims like "eco-friendly," "clean," or "non-toxic" without third-party verification. These are marketing terms, not chemical assurances.

The skin absorption question

Why does any of this matter?

During exercise, the heat and friction from movement can amplify chemical absorption, making it easier for PFAS to penetrate the skin barrier. This is especially concerning for people who wear activewear regularly or for long durations, such as athletes, fitness enthusiasts, or healthcare workers.

Skin is the body's largest organ. It's highly vascularized. Compounds absorbed through skin enter systemic circulation. For activewear worn during exercise, you're combining heat, sweat, friction, and prolonged contact with high-surface-area skin, including the inner thigh and groin area, which sits in close proximity to hormone-sensitive reproductive tissues.

The issue is not acute toxicity. Nobody is getting sick from wearing leggings once. The issue is chronic, cumulative load from daily exposure over years.

The consumer base for activewear made of natural materials like cotton and wool is growing, as more people across the political spectrum join in worrying about the health effects of polyester and other synthetics.

This is not a fringe concern anymore. It's becoming a purchasing criterion across demographics.

What this means for brand positioning

If you're an activewear founder, you have a choice:

Option A: Continue sourcing conventional synthetic activewear, hope your supply chain is compliant, and deal with regulatory and reputational risk as it emerges.

Option B: Proactively spec for chemical transparency, require third-party testing, and build that transparency into your brand story.

Option B costs more upfront. It requires harder conversations with factories. It may limit your supplier options.

But it also creates defensibility. When the next round of testing results makes headlines, when the next state passes PFAS restrictions, when the next lawsuit names major brands, you're positioned as the alternative.

At Ohzehn, we built our fabric architecture around this exact principle: 76% bio-based nylon, 24% bio-based stretch fiber, no PFAS, no antimicrobial silver, no fragrance infusion, third-party tested in U.S. labs for BPA, PFAS, phthalates, heavy metals, formaldehyde, and azo dyes. It's possible to build performance activewear without the chemical baggage. But you have to spec for it from the beginning.

The questions to ask your factory

Before your next production order, send these questions to your factory or fabric supplier:

1. Can you provide OEKO-TEX Standard 100 certification for the finished fabric?
2. Does the fabric contain any intentionally added PFAS, including DWR finishes?
3. What is the source of the spandex/elastane, and has it been tested for BPA?
4. Does the fabric contain antimicrobial silver or any embedded biocidal treatments?
5. Can you provide third-party test reports for heavy metals, formaldehyde, and azo dyes?
6. What finishing treatments are applied after dyeing?

If you get clear, documented answers to all six, you're ahead of most brands in the market.

If you get vague responses or pushback, you've identified where your supply chain risk lives.

The fiber content label is a starting point, not an endpoint

The label tells you nylon. It tells you elastane. It doesn't tell you what happened to that fiber between the spinning mill and the garment on your body.

For consumers, the gap is frustrating. For founders, it's an opportunity.

The brands that win the next decade of activewear will be the ones that can answer the chemistry question, not just the fiber question. That requires deeper spec work, harder supplier conversations, and a willingness to pay for third-party verification.

But it also means building something your customers can trust against their skin for 14 hours a day, 365 days a year.

That's the standard the market is moving toward. The question is whether you're building for it now.

Dougie Taylor

Co-Founder, Ohzehn Textiles · Building plastic-free performance apparel