Why Is Polyester Bad for You and the Environment?

Polyester poses a genuine double-sided problem: it carries chemicals that can transfer into your body through skin and lungs, and it sheds plastic fibers that persist in water, soil, and air for decades. Made from petroleum-derived polyethylene terephthalate (PET), polyester accounts for more than half of all fiber production worldwide, which means its downsides ripple through both personal health and global ecosystems at enormous scale. The concerns are not hypothetical, though the severity of individual risks depends heavily on exposure patterns, garment treatments, and how the fabric is washed and disposed of.

What Polyester Does to Your Skin

The most direct route of exposure is the simplest one: wearing polyester against your body. Polyester textiles routinely contain antimony, a heavy metal used as a catalyst during PET manufacturing. Testing of polyester garments has found total antimony concentrations ranging from about 125 to 470 micrograms per gram of fabric, and artificial sweat solutions can mobilize roughly 0.05 to 2 percent of that antimony through the textile surface.¹ That percentage sounds small, but when you account for a full day of skin contact over a large body area, the exposure adds up. One study found that antimony had the highest mean hazard quotient of all trace elements tested in skin-contact clothing, and for at least one polyester T-shirt, the hazard quotient exceeded the safety limit, meaning potential health risks for people who frequently wear polyester for extended periods.²

Sweat makes everything worse. Research on children’s textiles treated with per- and polyfluoroalkyl substances (PFAS) and organophosphate esters found that sweat amplified chemical absorption by staggering margins, up to thousands of times compared to dry contact.³ A separate study looking at quaternary ammonium compounds in clothing found that estimated daily intakes jumped from under 2 nanograms per kilogram of body weight per day for dry clothing to nearly 97 nanograms per kilogram per day for sweaty clothing under normal conditions, and much higher in high-exposure scenarios.⁴ The implication is clear: polyester worn during exercise, in hot climates, or during physical labor delivers meaningfully more chemicals into your skin than the same garment worn in cool, dry conditions.

Textile Dyes and Allergic Reactions

Beyond heavy metals and fabric treatments, polyester garments carry disperse dyes that are well-established skin allergens. These dyes are used heavily in synthetic fabrics because they bond well with hydrophobic fibers. A review of textile dermatitis found that certain disperse dyes, particularly Disperse Blue 106, Disperse Blue 124, and Disperse Orange 3, showed allergy prevalence rates above 1 percent in screening studies.⁵ That might seem like a small percentage, but applied to the billions of people wearing polyester daily, it translates into millions of potential sufferers.

In clinical testing, the connection between these dyes and polyester is stark. Among patients who reacted positively to textile dyes, the vast majority responded to Disperse Blue 106 and Disperse Blue 124. When those patients’ own clothing was tested, nine out of ten reactive cases traced back to blue or black polyester or acetate liners in their garments.⁶ If you have unexplained rashes, itching, or redness in areas where clothing sits snugly against your body, dark-colored polyester is a reasonable suspect.

Chemicals You Cannot See or Feel

The health concerns with polyester extend beyond what touches your skin. A recent critical review covering evidence from 2019 to 2025 flagged elevated risks from phthalates in infant clothing, PFAS in water-repellent fabrics, and carcinogenic aromatic amines released by azo dyes.⁷ These aren’t just theoretical hazards. Non-regulated halogenated aromatic compounds in clothing have been shown to migrate from textiles into sweat and be absorbed through the skin, with some also demonstrating mutagenic effects in laboratory testing.⁸

The trouble with these chemical exposures is that they are low-dose and chronic. You probably will not feel anything from a single day of wearing a polyester shirt. But the cumulative effect of daily, prolonged skin contact with a cocktail of antimony, disperse dyes, flame retardants, and finishing chemicals is harder to dismiss, especially for vulnerable groups like infants, people with compromised skin barriers, and workers who wear uniforms all day.

Why Polyester Smells Worse After a Workout

If you have ever noticed that your synthetic gym clothes develop a stubborn funk that cotton shirts seem to avoid, there is a microbiological explanation. Polyester selectively promotes the growth of odor-causing bacteria. A study comparing the microbial communities on polyester and cotton shirts after exercise found that micrococci, a group of bacteria strongly associated with malodor, were isolated from nearly all synthetic shirts and almost never from cotton ones. The fiber composition of the fabric itself drives this selective enrichment.⁹

This is not just an annoyance. Odor-causing bacterial communities can contribute to skin irritation, and the aggressive laundering needed to remove embedded smells from polyester (hotter water, stronger detergents, more frequent washing) compounds the environmental costs of owning synthetic clothing, as each wash cycle sheds microfibers into the water supply.

Microplastics Shed Into Water With Every Wash

Washing polyester releases enormous numbers of microscopic plastic fibers into wastewater. A study examining polyester, polyester-cotton blends, and acrylic fabrics found that a standard 6-kilogram load of synthetic fabric could release hundreds of thousands of fibers per wash, with individual fibers averaging roughly 12 to 18 micrometers in diameter and 5 to 8 millimeters in length.¹⁰ Another study reported that a single wash could release between 640,000 and 1.5 million microfibers per kilogram of fabric, with most fibers small enough to slip through wastewater treatment plants.¹¹

These fibers do not disappear after they leave your washing machine. Polyester microfibers have been identified as one of the most common types of microplastics found in both indoor and outdoor air.¹² Research on atmospheric microplastic sources consistently points to synthetic textiles as the primary contributor to airborne microplastics, with fibers being the dominant shape detected.¹³

Breathing In Microplastic Fibers

You are not just wearing polyester; you are inhaling fragments of it. Estimates suggest that adults inhale roughly 68,000 microplastic particles per day from indoor air alone, with children taking in about 47,000. These tiny particles can cross cellular barriers, enter the bloodstream, and carry adsorbed toxic additives including heavy metals and persistent organic pollutants.¹⁴ The research on long-term respiratory effects is still developing, but the combination of physical irritation from the fibers themselves and chemical exposure from their additive payload has prompted growing concern among environmental health researchers.

What Happens to Polyester in Soil and Landfills

Polyester is, for all practical purposes, permanent. Biodegradation studies consistently find that polyester fabric remains intact under composting conditions. In one study, cotton fabrics degraded substantially while polyester showed only slight initial surface changes but maintained its structural integrity in both laboratory and compost environments.¹⁵ A more recent study was even more blunt: synthetic fibers, including polyester, showed zero biodegradation under aerobic composting conditions.¹⁶

While sitting in landfills or dispersing through the environment, polyester microfibers alter the soil they accumulate in. Experiments have shown that polyester fibers change soil bulk density, pore structure, enzymatic activity, and bacterial communities, and these alterations persist even after thermal treatment intended to break the fibers down.¹⁷ In plant-growth trials, polyester fiber contamination in soil reduced plant biomass by roughly 30 percent and decreased nitrogen uptake by a comparable margin, while increasing nitrogen loss through leaching.¹¹ These findings suggest that as polyester microfibers build up in agricultural soils over time, they could meaningfully affect crop productivity.

The Carbon Cost of Making Polyester

Producing virgin polyester is energy-intensive. A lifecycle assessment found that manufacturing 100 kilograms of virgin polyester textiles generates about 120 kilograms of CO₂, with the single largest contributor being the production of terephthalic acid, one of the key chemical precursors, which accounted for nearly half of the total carbon footprint.¹⁸ The entire production chain, from crude oil refining through polymerization to fabric finishing, runs on fossil fuels at every stage.

When polyester textiles are burned rather than landfilled, as frequently happens in countries with less developed waste infrastructure, the emissions profile shifts from slow persistence to acute toxicity. Open burning of polyester waste releases particulate matter, polycyclic aromatic hydrocarbons, and toxic heavy metals, exposing nearby communities to concentrated air pollution.¹⁹

Wildlife and Ecosystem Effects

The ecological consequences of polyester microfibers go beyond soil chemistry. When synthetic microfibers enter aquatic environments, they are consumed by organisms across the food web. Ingestion of synthetic microfibers can disrupt feeding behaviors, impair growth, and compromise reproductive capabilities in marine and freshwater species, with effects that scale up to population-level impacts.²⁰ Because polyester fibers are among the most frequently identified microplastics in both water and sediment samples globally, their contribution to this problem is not peripheral. Polyester is, by volume, one of the main players.

Does Recycled Polyester Help

Recycled polyester, typically made from post-consumer PET bottles, has a substantially smaller carbon footprint during production. One analysis found that increasing the bio-based or recycled PET content in polyester fiber from zero to 100 percent dropped the carbon footprint from about 3.0 to 0.46 kilograms of CO₂ equivalent per kilogram of fiber.²¹ That is a meaningful improvement on the production side.

The catch is that recycled polyester does not solve the microfiber problem. A study directly comparing virgin and recycled polyester textiles found no statistically significant overall difference in the number of microplastic fibers released during washing.²² Recycled polyester also still contains antimony and can carry the same dyes and chemical treatments as virgin fabric. So while recycled polyester is the better environmental choice at the factory level, the garment you wear and wash behaves essentially the same once it is in your closet.

Bio-Based Polyester and Future Alternatives

Researchers are developing partially bio-based polyester resins that derive some of their chemical building blocks from plant sources instead of petroleum. Lifecycle assessments of these experimental materials show improved environmental performance in several categories, with reductions in climate-change impact of up to 90 percent in some formulations, and overall single-score impact reductions between 18 and 39 percent compared to conventional oil-based resins.²³ The tradeoffs are real, though: some bio-based formulations performed worse in categories like acidification and freshwater eutrophication, meaning the environmental gains are not uniform across all measures. These materials remain largely at the research stage and are not yet available in mainstream consumer textiles.

What Happens to the People Who Make Polyester

The health burden of polyester does not fall equally. Workers in textile manufacturing face concentrated chemical exposures that consumers never experience. An epidemiological study of textile factory workers found a strong correlation between chemical substance use, working conditions, and symptoms including dermatitis, otolaryngological complaints, and eye problems.²⁴ A cross-sectional study of Turkish textile workers found that about one in ten participants had skin complaints such as itching, redness, dryness, or blistering from chemical exposure in just the previous week, and two-thirds of workers who used chemicals could not even identify which ones they were handling.²⁵

These occupational exposures are orders of magnitude higher than what a consumer encounters from wearing the finished product, which means the health argument against polyester is not just about the person wearing the shirt. It extends through the supply chain to communities where textiles are dyed, treated, and assembled.

Practical Steps That Actually Reduce Harm

If you are not ready to abandon polyester entirely, and most people are not given its dominance in affordable clothing, there are a few evidence-based steps that meaningfully reduce both personal exposure and environmental shedding.

Washing machine filters are the single most effective consumer-level intervention for microfiber pollution. Various filter designs have been tested, with retention efficiencies ranging from about 50 percent on the first wash to above 90 percent after repeated use as the filter media compact.²⁶ Newer bio-inspired filter designs featuring barbed structures have achieved retention rates of 88 to 91 percent, outperforming conventional filters.²⁷ France has already legislated that new washing machines must include microfiber filters, and similar requirements are under consideration elsewhere.

For personal chemical exposure, the simplest strategies are the most effective. Wash new polyester garments before wearing them, since some chemical residues are highest on first contact. Choose lighter-colored polyester when possible, since darker dyes (especially blues and blacks) are most strongly linked to skin allergies. Opt for natural fibers in garments that sit directly against skin for extended periods, particularly sleepwear, underwear, and workout gear you will sweat through. Polyester-cotton blends shed fewer microfibers than pure polyester, so blended fabrics represent a partial compromise.¹⁰ Wash synthetic clothes less frequently, at lower temperatures, and with liquid detergent rather than powder, all of which tend to reduce fiber release. And when polyester garments reach end of life, donate or recycle them rather than sending them to landfill, where they will sit essentially unchanged for generations.