Does Polyester Cause Cancer?

The short answer

No. No human study has shown that wearing polyester clothing causes cancer.

The International Agency for Research on Cancer — the World Health Organization body that classifies carcinogens — has evaluated organic polymeric materials as a class, the category that covers polyethylene terephthalate, the polymer polyester is made from. Its conclusion: Group 3, not classifiable as to carcinogenicity in humans. IARC has never separately evaluated PET itself, and that evaluation covered plastics surgically implanted inside the body, a far heavier exposure than a shirt against your skin.

But "polyester doesn't cause cancer" is not the same statement as "everything in a polyester garment is fine."

Those are two different questions, and the second one has real answers. What follows is the evidence on both — including the parts that don't help us sell anything.

Why the question keeps coming up

Three things collided over the last few years. Microplastics started showing up in human blood, lung tissue and placenta, which made people think harder about the plastic they wear. Independent labs began testing activewear and found BPA and PFAS in name-brand products. And a wave of social content compressed all of it into a single scary sentence.

The compression is the problem. "Polyester contains antimony, and antimony is a probable carcinogen" is technically true and practically misleading, because it skips the only question that determines whether something can hurt you: how much of it actually reaches you.

It also isn't a fringe concern any more. Polyester is 59% of global fiber production, according to Textile Exchange's 2025 Materials Market Report — 132 million tonnes of fiber made in 2024, 88% of the polyester in it from fossil feedstocks. It's in most activewear, most fast fashion, most hotel bedding and most golf shirts. When a material is that ubiquitous, "is this doing something to me?" is a reasonable question. The answer being reassuring on cancer doesn't make the question stupid.

There is also a structural reason the instinct is sound. Most people assume someone is checking what goes into clothing the way agencies check 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 the whole reason certifications carry so much weight further down this page — in a category with real oversight, they would be a formality.

The four chemicals people are actually asking about

1. Antimony — measurable, and below the regulatory limit

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. Both rest on limited human evidence of lung cancer among workers inhaling antimony dust and fume, plus animal inhalation studies — not on skin contact with fabric. Antimony trioxide also appears on California's Proposition 65 list.

So how much comes out of clothing? A 2021 study by Biver, Turner and Filella ran polyester textiles through three successive 24-hour extractions in artificial sweat at body temperature. Total antimony in the fabrics measured 125 to 471 micrograms per gram. Between 0.05% and 2% of it migrated out — 0.1 to 1 microgram per gram of textile in most samples, with the single highest figure, 2.57, coming from a microfiber cleaning cloth rather than a garment. For context, the OEKO-TEX Standard 100 limit for extractable antimony in skin-contact textiles is 30 micrograms per gram, measured by a comparable acidic sweat extraction.

Every measured release sat below that limit. Most of it came off in the first extraction, which is why their practical advice was simply to wash synthetic garments before wearing them, more than once if you like. Manufacturers and regulators should pay attention to it, and that the test method needs standardizing.

2. PFAS — the one that deserves your attention

PFAS aren't inherent to polyester. They're added — usually as durable water-repellent and stain-resistant finishes, sometimes as processing aids. And this is the only place on this page where a Group 1 human carcinogen lines up with something you can actually act on: in November 2023, IARC classified PFOA as Group 1, carcinogenic to humans, and PFOS as Group 2B.

The exposure isn't hypothetical either. 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 but not in the US.

One thing to rembmer, PFAS track the finish, not the fiber. A plain polyester t-shirt is a different product from a quick-dry polyester shirt, and the marketing language on the tag is a better predictor of potential carcinogens, than the fabric content.

3. BPA — documented in activewear

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 finishes — real carcinogens, mostly on other fibers

This is where the actual Group 1 classifications live.

Benzidine and benzidine-based azo dyes are IARC Group 1. Formaldehyde is Group 1 in its own right, on occupational inhalation evidence, and formaldehyde-releasing resins are used in wrinkle-resistant finishes. But benzidine-based azo dyes bind to cellulosic fibers and leather — cotton, viscose, linen — not to polyester, which takes disperse dyes instead.  Easy-care formaldehyde treatments go onto cotton and cotton blends. If you are worried about textile carcinogens specifically, you are mostly worried about treated fibers.

Both are tightly capped in the EU but not the US: azo dyes that release any of 22 listed aromatic amines are limited to 30 mg/kg under REACH Annex XVII entry 43, and formaldehyde in direct-skin-contact clothing to 75 mg/kg under entry 72, in force since November 2020 — the same number OEKO-TEX uses. The practical risk today sits with uncertified goods from unregulated supply chains.

Polyester's own dye issue is a different one, and it's covered further down: disperse dyes and contact allergy, not cancer.

What about microplastics?

Polyester garments shed microfibers — in the wash, in the dryer, and while you wear them. Microplastics have since been detected in human blood, lung tissue and placenta.

What that means for health is genuinely unknown, and anyone who tells you otherwise is ahead of the evidence. 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."

That's the honest position. Microplastic exposure from clothing is real and rising. A causal link to cancer in humans has not been established. Both sentences are true at the same time.

Does polyester cause infertility?

This one deserves its own answer, because it's the most confidently repeated claim online and it rests almost entirely on one researcher.

Between 1992 and 1993, Egyptian surgeon Ahmed Shafik ran a series of experiments putting underwear on animals and men. Seventy-five male rats wore fitted polyester, cotton, wool or blended underpants for six to twelve months. He ran a parallel dog study, and two small human studies: 21 men for electrostatic measurements on the scrotal surface, and 14 men fitted with a polyester scrotal sling. He reported that polyester generated electrostatic charges across genital tissue and was associated with reduced sperm counts and reduced sexual activity. In the sling study, all 14 men became azoospermic at a mean of 139.6 days.

Four things to hold onto. The effects largely reversed when the polyester came off — sperm counts returned to baseline in the men at a mean of 157 days, with four live births among five couples who then tried to conceive, though in the dog study 10 of 12 recovered and two stayed oligozoospermic. The human groups were far too small to establish anything definitive. The exposure was continuous, tight-fitting, 24-hour wear over months, which is not how anyone dresses. And there has been essentially no modern follow-up: one independent Indonesian group reproduced the sling effect in 1995 using the same continuous-wear design, and beyond that the work has sat untested for thirty years. No study has ever tested ordinary polyester underwear worn the way people actually wear it. A 2025 review of this literature characterizes it as hypothesis-generating rather than evidence of clinically relevant fabric effects, and notes the electrostatic mechanism was never independently validated.

Marino, the toxicologist quoted above, told NPR flatly: "It has not been proven that polyester causes infertility in humans."

Rat pants are a real experiment. They are not a reason to panic about your gym shorts.

Is polyester bad for your skin?

NPR's toxicologist said "at the very least, it can trigger skin irritation."

The most specific documented mechanism is chemical rather than physical. Polyester is dyed with disperse dyes, several of which — Disperse Blue 106 and 124 among them — are recognized contact allergens and appear on standard dermatology patch-test series. They are essentially specific dyes for synthetics. Add trapped moisture and friction and it's a routine trigger for contact dermatitis or heat rash.

The odor is a separate, better-characterized phenomenon. In a controlled study of shirts worn during a fitness session, polyester carried odor-producing Micrococcus species that were almost entirely absent from cotton, and because synthetic fibers adsorb odor compounds poorly, those volatiles release into the air rather than staying in the fabric. Polyester is hydrophobic: it moves sweat along the surface instead of absorbing it. The result is a shirt that smells stronger and faster than a cotton one.

The evidence at a glance

Every claim on this page, with what actually supports it:

Which polyester actually matters

Treating all polyester as one thing is what makes this topic useless. Exposure varies enormously by product. Roughly ranked:

If you change one buying habit, stop buying things sold on stain resistance and water repellency. That's the row with actual chemistry behind it.

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. Wicking, stretch and durability are properties of the polymer itself and carry no added chemistry. Water repellency, stain resistant and wrinkle resistance are almost always a finish applied afterwards, and finishes are where the PFAS is. A fabric engineered to be cool or odor-resistant at the fiber level needs no topical treatment to stay that way through washing. Treat "water-repellent," "stain-resistant" and "wrinkle-free" as ingredient claims. They describe a chemical finish, and they're the best available predictor of PFAS. 
• Wash new synthetics before wearing them. Most of the extractable antimony comes off in the first wash or two, and it costs you nothing. It does not remove a durable water-repellent finish — that's what "durable" means — so washing is no substitute for avoiding PFAS-treated goods in the first place.
• 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 — an uncertified organic cotton shirt has been tested for none of it.
• Audit what you wear constantly, not everything 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, and underwear, account for most of it. Prioritize what touches you when you're hot. 
• Wash cold, air dry when you can, use a filter bag. Cuts microfiber shedding into the water system.
• Don't throw out your closet. Fast-replacing a wardrobe is its own problem. Replace as things wear out.

The bottom line

Polyester does not cause cancer, as far as any evidence currently shows. 

What is documented is narrower and more actionable. PFAS finishes are a real exposure, PFOA is a Group 1 human carcinogen, and both are avoidable by reading a tag. BPA turns up in activewear more often than it should. Antimony is present but migrates at levels below regulatory limits. Microplastic exposure is real and its health effects are unresolved. And polyester's most reliable effects on your body are that it traps heat, smells faster, and carries dyes that irritate some people's 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).
• Mastrangelo et al. (2002), "Epidemiologic evidence of cancer risk in textile industry workers: a review and update," Toxicology and Industrial Health 18(4).
• Ratelle et al. (2025), postmenopausal breast cancer and occupational exposure to textile fibers and dusts, Montreal 2008–2011, Journal of Occupational and Environmental Medicine, July 2025 (CRCHUM / Université de Montréal / McGill).
• Shafik (1992, 1993) on textile fabric, electrostatic potentials and spermatogenesis; Moeloek (1995), Medical Journal of Indonesia.
• 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.