The toxic truth behind performance wear

Performance wear has spent two decades selling stretch, sweat-wicking and water repellence as a wellness upgrade. But the truth underneath is murkier, as the chemistry that makes those features possible is now the subject of lawsuits, bans and a fast-growing body of evidence linking it to real harm.

A wave of investigative reporting, lawsuits and state-level legislation has put PFAS, formaldehyde, azo dyes and other finishing chemicals under the spotlight. In September 2025, a California jury awarded five American Airlines flight attendants $18.6 million in damages, finding that uniforms supplied by manufacturer Twin Hill had caused serious skin and respiratory illness; the jury assigned 90% of the liability to Twin Hill and 10% to the airline. It’s one of dozens of similar claims working through US courts, with rulings going both ways – a federal appeals court sided with American Airlines and Twin Hill on a separate claim just last week, underlining how legally contested, but reputationally damaging, this territory remains. In 2023, the period care brand Thinx separately settled a lawsuit over fluorine levels found in its underwear. For an industry that has spent two decades selling synthetic performance fabric as a wellness upgrade, the optics are getting harder to manage.

While it’s true that many types of clothing contain these harmful chemicals, activewear and performance apparel is a particular pressure point. Stretch, recovery, water repellence, moisture-wicking and odour control are now baseline expectations rather than differentiators, and most of that functionality has historically come from synthetic fibres layered with chemical finishes, with sweat and skin heat accelerating the transfer of those chemicals into the body. Regulation is gathering pace and bolstering consumer expectations. In the US, California, New York, Maine, Vermont and Connecticut have all introduced PFAS restrictions on apparel, while the EU is tightening REACH (Registration, Authorisation and restriction of Chemicals) thresholds throughout 2026, and the US EPA’s ban on the PBT chemical PIP (3:1) takes full effect from 31 October 2026.

Green fibre manufacturers are now stepping in to fill the gap. Lenzing and Hyosung TNC, the world’s largest spandex manufacturer, have partnered on a yoga fabric collection that blends Lenzing’s Tencel Lyocell and Ecovero with Hyosung’s bio-based Regen elastane, aiming to match conventional stretch and recovery without relying on virgin synthetics or the finishing chemistry that typically accompanies them. Hyosung has also paired with biotech firm Geno to shift its elastane feedstock from corn to sugarcane, with ambitions to scale up to 50,000 tonnes of bio-based BDO by the end of 2026 – the first integrated regional supply chain of its kind. Elsewhere, brands such as Ridestore are pushing fluorine-free water repellency and natural-fibre technical ranges as standard rather than premium add-ons, following outdoor peers like Patagonia, Vaude and Páramo, who have already proven that PFAS-free DWR can match conventional performance in independent testing.

Consumer awareness is catching up fast. Netflix documentary The Plastic Detox, which premiered in March 2026, follows six couples reducing their exposure to phthalates and bisphenols – including swapping synthetic wardrobes for cotton and wool – and ties that exposure directly to fertility outcomes, putting the issue in front of a mainstream streaming audience. Meanwhile in London, The Mills Fabrica’s Performance Without Toxicity exhibition at Fabrica X has spent the first half of 2026 putting PFAS-free waterproofing, microbial dyeing and compostable footwear in front of the public and industry alike, framing clean chemistry as the next performance benchmark rather than a compromise. Both signal the same shift: this conversation has moved from chemical disclosure labels to lived health concerns playing out in the public eye, and brands are beginning to respond to a more informed consumer rather than reacting to backlash after the fact.

Those consumers now have more everyday options to point to. US essentials brand Pact has built its proposition around its “Gentle-on-Skin” certified organic cotton, marketing its core range as free from toxic dyes, harsh chemicals and PFAS – another signal that clean chemistry is moving beyond technical performance wear and into the basics layer that sits underneath it.

The scale question is the one that matters now. Bio-based elastane and certified low-impact cellulosics solve the chemistry problem, but they still depend on the same constraints as any emerging material: feedstock supply, mill capacity, and a cost premium that has to be absorbed somewhere in the value chain. What’s shifted is the commercial logic for absorbing it. With disclosure laws expanding state by state, the cost of getting caught out – in lawsuits, recalls or reputational damage – is rising in parallel with consumer willingness to pay for verified, certified chemistry. That changes the calculation for brands sitting on the fence.

For brand and retail leaders, the takeaway isn’t that natural fibres will fully replace synthetics in performance categories – realistically they almost certainly won’t, at least not in the near term. It’s that “clean performance” is moving from niche claim to baseline expectation, and the brands that can prove their chemistry rather than simply assert it will be the ones consumers and regulators trust first.