Is Your Activewear Toxic? PFAS Chemicals in Sports Clothing Explained

Gym clothes are sold on performance. Sweat-wicking, quick-drying, odour-resistant. What they don't tell you is how some of those properties are achieved, and what's actually in the fabric sitting against your skin while you work out.

PFAS (per- and polyfluoroalkyl substances) are a class of synthetic chemicals used widely in activewear and sportswear. They're also sometimes called "forever chemicals" because they don't break down, not in the environment and not in your body.

What are PFAS?

PFAS is an umbrella term for a group of over 10,000 synthetic chemicals that share a carbon-fluorine bond, one of the strongest in organic chemistry. That's what makes them so persistent: they resist heat, water, oil and degradation.

They've been used since the 1950s in non-stick cookware, food packaging, firefighting foam and waterproof clothing. The two most studied, PFOA and PFOS have been phased out in many countries after being linked to serious health effects. But thousands of similar compounds are still in use, and the science on most of them is decades behind the industry.

Why are PFAS in sports clothing?

The properties that make PFAS useful in non-stick pans are the same properties the clothing industry exploits. PFAS-based durable water-repellent (DWR) finishes are applied to the surface of fabrics to make them shed water rather than absorb it. This is especially common in:

• Technical outerwear and rain jackets
• Running shorts and gym gear with water-resistant claims
• Swimwear and surf apparel
• Performance base layers

Some brands have moved away from PFAS-based DWR. Many haven't, and labelling isn't required, so you often can't tell from the packaging.

What are the health effects?

The health evidence for the most studied PFAS is significant. PFOA and PFOS have been linked to kidney and testicular cancer, thyroid disease, elevated cholesterol, immune system disruption and reduced vaccine effectiveness. They've also been found in human blood, breast milk and umbilical cord blood.

The critical point about PFAS is bioaccumulation: they don't clear out of the body quickly. They build up over years of ongoing exposure. And unlike a single contamination event, wearing PFAS-treated clothing is a recurring, direct skin-contact exposure.

We covered the broader topic of toxic chemicals in clothing in our post on PFAS and forever chemicals in clothing.

Is activewear the worst offender?

It's up there. Activewear is designed to be worn close to skin, through heat and sweat, for long periods. Those conditions of warmth, moisture, friction are exactly when chemical migration from treated synthetic fabrics is most likely to occur. Researchers at Indiana University found that athletes who wear technical synthetic sportswear regularly had higher PFAS blood levels than the general population.

The irony is real. You're working out to improve your health and wearing something that may be quietly working against it.

What should you use instead?

Natural fibres. Merino wool is the strongest alternative in performance clothing because it achieves moisture management, temperature regulation and odour resistance through the physical properties of the fibre itself, not chemical finishes. There's no PFAS, no DWR coating, no synthetic treatment required for it to perform.

100% natural merino shorts manage sweat and dry quickly because of how the fibre is structured, not because of anything sprayed on top. If you want to compare options, we put together a guide to the best non-toxic men's shorts in Australia.

How to check if your activewear contains PFAS

It's harder than it should be. A few things to look for:

• Water-resistant or DWR claims often mean PFAS-based treatments are present unless explicitly stated otherwise.
• Certifications like bluesign®, OEKO-TEX STANDARD 100 and fluorocarbon-free (FC-free) claims are worth looking for.
• When in doubt, contact the brand directly. Transparency on PFAS varies significantly.

FAQs

What are PFAS chemicals in clothing?

PFAS (per- and polyfluoroalkyl substances) are synthetic chemicals used in water-resistant treatments on clothing and textiles. They don't break down in the environment or the body and have been linked to serious health effects including cancer, thyroid disease and immune disruption.

Is all activewear treated with PFAS?

No, but a significant portion is, especially anything with water-repellent or DWR claims. Natural-fibre performance clothing achieves its properties without chemical finishes.

How do PFAS get into your body from clothing?

Primarily through skin absorption and inhalation of fibres. Conditions during exercise increase the likelihood of chemical migration from treated synthetic fabrics.

What's a safe alternative to synthetic activewear?

Natural fibres, particularly merino wool, achieve performance properties through fibre structure rather than chemical treatments. No DWR, no PFAS, no synthetic finishes needed.

Sources

• ECHA (European Chemicals Agency): PFAS restriction proposal and health evidence
• Indiana University (2020), PFAS Exposure in Olympic Athletes
• US EPA: PFAS overview and regulation
• ECDC: health effects of PFOA and PFOS

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