Is polyester bad for you? What the research shows
Polyester is 59% of the fiber the world makes, so most people wear it every day without deciding to. It is plastic, and what makes it a problem is what comes with it.
What is in a polyester shirt
| Issue | Polyester | Natural fibers |
|---|---|---|
| What it is | Plastic (PET), mostly from fossil fuels | Grown: cotton, linen, hemp, wool, silk |
| Catalyst residue | Antimony, which moves into sweat in lab tests | None; the fiber is not polymerized |
| Water and stain finishes | Often PFAS | Choose fabrics with no PFAS finish |
| Odor | Smells worse after exercise; hosts odor bacteria | Cotton smelled less in the same study |
| Microfibers | Sheds plastic in every wash and wear | No plastic microfibers |
Antimony in the fiber
Most polyester is made with an antimony catalyst, and some of it stays in the fiber. In lab tests, antimony moved from polyester textiles into artificial sweat, and warm, acidic sweat pulled out the most. Antimony trioxide is classified by IARC as probably carcinogenic to humans (Group 2A).
PFAS finishes
Polyester cannot repel water or stains on its own, so those properties are sprayed on. In a 2022 investigation, 72% of products marketed as stain- or water-resistant contained PFAS. PFOA, the best-known PFAS, is classified by IARC as carcinogenic to humans (Group 1).
Odor
Polyester holds odor. Shirts worn to a workout smelled significantly more intense and less pleasant in polyester than in cotton, and the odor-producing bacteria grew almost only on the polyester.
Microfibers
Polyester sheds plastic. One 6 kg wash released about 496,000 microfibers, and normal wear sheds up to 400 fibers per gram of fabric in 20 minutes.
Frequently asked questions
Is polyester toxic to wear?
Polyester carries chemicals that are. Antimony catalyst residue moves from the fiber into artificial sweat in lab tests, and antimony trioxide is probably carcinogenic (IARC 2A). Many water- and stain-repellent finishes use PFAS; PFOA is carcinogenic to humans (IARC Group 1).
Why does polyester smell more than cotton?
Because odor bacteria thrive on it. In a 2014 study, polyester shirts worn to a workout smelled significantly more intense and less pleasant than cotton, and odor-producing Micrococcus bacteria grew almost only on the polyester.
Does washing polyester before wearing it help?
It removes some loose residue, but it does not change what the fiber is. Durable water-repellent finishes are designed to survive washing, and every wash sheds plastic microfibers into the water.
Sources
- Biver M, Turner A, Filella M (2021), Antimony release from polyester textiles by artificial sweat solutions, Regulatory Toxicology and Pharmacology 119:104824. doi.org
- IARC Monographs Volume 131 (2023), Cobalt, antimony compounds, and weapons-grade tungsten alloy. monographs.iarc.who.int
- Toxic-Free Future (2022), Toxic Convenience: The hidden costs of forever chemicals in stain- and water-resistant products. toxicfreefuture.org
- IARC Monographs Volume 135 (2023), PFOA and PFOS; summarized in Zahm S et al., The Lancet Oncology 25(1):16–17, 2024. iarc.who.int
- Callewaert C et al. (2014), Microbial Odor Profile of Polyester and Cotton Clothes after a Fitness Session, Applied and Environmental Microbiology 80(21). journals.asm.org
- Napper IE, Thompson RC (2016), Release of synthetic microplastic plastic fibres from domestic washing machines, Marine Pollution Bulletin 112. doi.org
- De Falco F et al. (2020), Microfiber Release to Water, Via Laundering, and to Air, via Everyday Use, Environmental Science & Technology 54(6). pubmed.ncbi.nlm.nih.gov
- Textile Exchange (2025), Materials Market Report 2025. textileexchange.org