Does Polyester Cause Cancer?

The short answer

Some finishes sprayed on polyester clothing are known to cause cancer. In a 2022 Toxic-Free Future investigation, 72% of products marketed as stain- or water-resistant tested positive for PFAS, some of which are Group 1, carcinogenic to humans. Polyester the fiber has not been shown to cause cancer. Polyester the performance product, sprayed to repel water and stains, carries a Group 1 carcinogen on it.

The International Agency for Research on Cancer, the World Health Organization body that classifies carcinogens, has evaluated organic polymeric materials as a class. That class covers polyethylene terephthalate, the plastic polyester is made from. Its conclusion: Group 3, not classifiable as to carcinogenicity in humans. Group 3 means the evidence has not been gathered, not that polyester passed. IARC has never separately evaluated PET itself.

That settles the cancer question and nothing else. Polyester is plastic. It carries an antimony catalyst in the fiber, it is where PFAS finishes and BPA keep turning up, its dyes are recognized contact allergens, it sheds microfibers and it holds heat and odor. Every one of those is documented, and every one is a reason to take it off your skin. What follows is the evidence, and what HyperNatural built instead.

Why the question keeps coming up

Because polyester is everywhere. Three things collided over the last few years. Microplastics started showing up in human blood, lung tissue and placentas, which made people think harder about the plastic they wear. Independent labs began testing activewear and found BPA and PFAS in name-brand products. Plus we know that polyester contains antimony, and antimony is a probable carcinogen that migrates into sweat.

Polyester is 59% of global fiber production, according to Textile Exchange's 2025 Materials Market Report: 132 million tonnes of fiber made in 2024. It is in most activewear, most fast fashion, most hotel bedding and most golf shirts. It is not there because it is good to wear. It is there because it is cheap to make and easy to print. When a material chosen for its price "is this doing something to me?" is the right question.

Nobody is checking, either. Most people assume someone inspects what goes into clothing the way agencies inspect what goes into food. For apparel sold into the United States, no such system exists. Textile supply chains are among the least transparent in any consumer category: a finished shirt can pass through spinning, knitting, dyeing and finishing in three or four countries, each stage adding chemistry, before anyone in the importing market handles it.

What exists instead is voluntary certification. That is why HyperNatural publishes its certifications, OEKO-TEX® Standard 100 and bluesign®, and why they carry so much weight.

The four chemicals people are actually asking about

1. PFAS: the one that deserves your attention

This is the one to act on. PFAS are not in the polyester polymer; they are sprayed onto it, usually as durable water-repellent and stain-resistant finishes, sometimes as processing aids, because water repellency and stain resistance are not in the fiber and have to be added. And this is the place on this page where a Group 1 human carcinogen lines up with something you can act on: in November 2023, IARC classified PFOA as Group 1, carcinogenic to humans, and PFOS as Group 2B.

The exposure isn't hypothetical. In a 2022 Toxic-Free Future investigation, 34 of 47 products marketed as stain- or water-resistant contained PFAS, 72%, across outdoor apparel, bedding and table linens from ten major retailers, with some jackets measuring up to 8% fluorine. Of the products that did contain PFAS, roughly three quarters (25 of 34) contained older types already banned in the EU. 

The marketing language on the tag is the best predictor of what is on it, and "water-repellent" and "stain-resistant" are the two phrases that mean a fluorochemical was sprayed onto plastic and sold to you as performance. 

HyperNatural does not spray performance on. The cooling comes from Hyper-Cool Jade®, jade minerals embedded in the fiber that conduct heat away from your skin. Odor control comes from Hyper-Chitin, chitin from crab shells in the fiber, a natural antimicrobial. Neither is a topical treatment, so there is nothing to wash off, and no PFAS finish is applied to any HyperNatural fabric.

2. Antimony: a heavy metal in the fiber, measurable in your sweat

Polyester ships with a heavy metal in it. Most polyester is polymerized using antimony trioxide as a catalyst, and trace antimony stays in the finished fiber. Antimony trioxide has been IARC Group 2B, possibly carcinogenic, since 1989, and in 2022 IARC classified trivalent antimony compounds as a class as Group 2A, probably carcinogenic to humans.

3. BPA: documented in activewear

Polyester activewear is where BPA keeps turning up. Bisphenol A is an endocrine disruptor. The Center for Environmental Health has tested polyester-based sports bras, athletic shirts and socks and reported BPA at levels it says exceed California's Proposition 65 safe-harbor threshold for skin exposure, up to 40 times over for some sports bras, naming well-known athletic brands. Several of those cases moved through the California legal system and pushed reformulation.

4. Dyes and contact allergies

Polyester's disperse dyes can cause contact allergy, not cancer.  Disperse Blue 106 and 124 are recognized contact allergens and appear on standard dermatology patch-test series. They are essentially specific to synthetics. Add trapped moisture and friction, and for anyone prone to eczema, contact dermatitis or heat rash, polyester is a routine trigger.

What about microplastics?

Polyester sheds plastic: microfibers in the wash, in the dryer and while you wear it. Microplastics have since been detected in human blood, lung tissue and in testicles.

What they do there is not yet known. Aron Stubbins, a professor of marine and environmental sciences at Northeastern University, described the state of the field to NPR: "For lots of that research, we're kind of at the point of understanding just where the plastics are, and then once we understand where they are, trying to figure out what impact they're having." 

HyperNatural's third path is not a cleaner plastic; it is a fiber that is not plastic. The base is Supima® extra-long-staple cotton, with 0% polyester, so there is no polyester microfiber to shed in the wash, in the dryer or against your skin.

The evidence at a glance

Which polyester actually matters

Not all polyester sits on your body the same way. Exposure varies by product. Roughly ranked, worst first:

If you change one buying habit, stop buying anything sold on stain resistance and water repellency. That is the row with the Group 1 carcinogen behind it. If you change two, take the polyester out of whatever you sweat in, which is where HyperNatural starts: polos, tees and shirts, the garments that sit against damp skin for hours.

What to actually do

• Ask whether the performance was built into the fiber or sprayed onto it. This is the distinction that does most of the work on this page. Water repellency, stain resistance and wrinkle resistance are almost always a finish applied afterwards, and finishes are where the PFAS is. 
• Look for OEKO-TEX® Standard 100 or bluesign®. These test the finished textile against published limits for antimony, BPA, PFOA, formaldehyde and banned azo dyes. Certification tells you more than a fiber name does. "Sustainable," "organic" and "non-toxic" mean nothing until the label names a fiber and a certificate, and an uncertified organic cotton shirt has been tested for none of it. 
• Audit what you wear constantly, not what you own. Exposure is a function of hours against skin, so the handful of items in heavy rotation, the base layer you train in twice a week, the shirt you travel in, underwear, account for most of it. Prioritize what touches you when you're hot: base layers, underwear, workout gear, the polo you play eighteen holes in. The polyester worn for hours against damp skin goes first, and that is the garment HyperNatural was designed to replace.
• Don't throw out your closet. Fast-replacing a wardrobe is its own waste problem. Replace polyester as it wears out, and don't replace it with polyester. Replace it with something that was built for skin.

The bottom line

Polyester does not cause cancer, as far as any evidence shows. That is the only pass it gets.

Polyester is plastic. It carries an antimony catalyst that migrates into your sweat, below regulatory limits and still a probable carcinogen that a cotton shirt does not have. It is the fabric PFAS finishes get sprayed onto, and PFOA is a Group 1 human carcinogen you can avoid by reading a tag. BPA turns up in polyester activewear often enough to force reformulation. It sheds microplastics, and nobody yet knows what those do inside you. And its most reliable effects on your body are that it traps heat, smells faster and carries dyes that irritate skin.

Sources

• IARC Monographs Vol. 74, Surgical Implants and Other Foreign Bodies (1999) — organic polymeric materials, Group 3.
• IARC Monographs Vol. 131, Cobalt, Antimony Compounds, and Weapons-Grade Tungsten Alloy (2022) — trivalent antimony, Group 2A; Vol. 47 (1989) — antimony trioxide, Group 2B.
• IARC Monographs Vol. 135 (2023) — PFOA, Group 1; PFOS, Group 2B.
• IARC Monographs Vol. 100F (2012) — benzidine and benzidine-based dyes, formaldehyde, Group 1.
• Biver, Turner & Filella (2021), "Antimony release from polyester textiles by artificial sweat solutions," Regulatory Toxicology and Pharmacology 119:104824.
• OEKO-TEX® Standard 100, Annex 4 limit values — antimony 30 mg/kg, BPA 10 mg/kg, PFOA 25 µg/kg, formaldehyde 75 mg/kg (Product Class II).
• REACH Annex XVII, entries 43 (azo dyes) and 72 (formaldehyde in textiles).
• Toxic-Free Future (2022), PFAS testing of stain- and water-resistant clothing, bedding and textiles.
• Center for Environmental Health, BPA testing of sports bras, athletic shirts and socks (2022–2023).
• Callewaert et al. (2014), "Microbial odor profile of polyester and cotton clothes after a fitness session," Applied and Environmental Microbiology.
• Textile Exchange, Materials Market Report 2025.
• NPR (20 January 2026), "Polyester clothing has been causing a stir online" — expert comment from Ryan Marino, MD and Aron Stubbins, PhD.

This article is for general information and is not medical advice.