Why I Stopped Wearing Plastic (And You Might Want To, Too)

Most people don't think of their t-shirt as plastic. But if the tag says polyester, nylon, acrylic, or spandex, that's exactly what it is. Petroleum-based plastic, woven into fabric, pressed against your skin for 12+ hours a day.

I switched to natural fibers a few years ago for environmental reasons. The health research I found along the way is what made me stay. And honestly, once I started reading about what these fabrics do inside our bodies, I couldn't go back. Not for my ski base layers, not for my mountain biking kit, not even for the cozy blanket on my couch where Whitley (my cat) and I spend most of our evenings.

Your Clothes Are a Chemical Delivery System

Synthetic fabrics aren't just plastic. They're treated with a cocktail of chemical additives during manufacturing. Phthalates to make them flexible. BPA to improve durability and moisture-wicking. PFAS to make them water-repellent. Flame retardants to meet safety regulations. Formaldehyde to prevent wrinkling.

These chemicals don't stay locked in the fabric. A 2024 study from the University of Birmingham found that chemical additives in microplastics leach into human sweat and are then absorbed through the skin into the bloodstream. The study showed that up to 8% of the chemicals exposed to skin were absorbed. And the more you sweat, the more you absorb.

Read that again: the more you sweat, the more you absorb.

So that polyester workout shirt you wear to the gym? Or the synthetic base layer you pull on before a ski day? It's releasing chemicals at the exact moment your skin is most absorbent.

Study: birmingham.ac.uk/news/2024/toxic-chemicals-from-microplastics-can-be-absorbed-through-skin

Hormone Disruption Is the Big One

Many of the chemicals found in synthetic clothing are classified as endocrine-disrupting chemicals (EDCs). They interfere with your hormonal system, the system that regulates metabolism, mood, sleep, growth, and reproduction.

BPA, which has been detected in sports bras and athletic wear from 19 major brands, mimics estrogen in the body. It binds to estrogen receptors and disrupts normal hormone signaling. A 2022 study in the Journal of Clinical Medicine found higher prevalence of PCOS in women with elevated BPA levels in their blood.

Phthalates, another common additive in synthetic textiles, have been linked to decreased pregnancy rates, increased miscarriage, and pregnancy complications in a study published in Best Practice & Research Clinical Endocrinology & Metabolism (September 2021).

Then there's PFAS. Often called "forever chemicals" because the body essentially can't break them down. They've been connected to reduced fertility, weakened immune response, and increased cancer risk, including prostate, kidney, and testicular cancers.

Study on BPA in athletic wear: ceh.org/latest/news-coverage/do-your-workout-clothes-contain-endocrine-disrupting-microplastics Study on phthalates and fertility: discovermagazine.com/fabrics-like-polyester-can-contain-a-number-of-chemicals-that-might-impact-47664

The Fertility Research Is Hard to Ignore

This is where the data gets uncomfortable.

A 1990 study found that men wearing polyester underwear showed reduced sperm count and motility, with some developing azoospermia (zero sperm production) after 139 days of wear. The effects reversed after switching to cotton. A 1993 animal study confirmed the same pattern with significant decreases in sperm count and increases in sperm abnormalities in subjects wearing polyester versus cotton.

Microplastics shed from synthetic clothing have now been detected in human blood, placentas, and sperm fluid. We don't yet have large-scale human trials proving direct causation between polyester clothing and infertility, but the chemical exposure pathways are well-established. The existing research all points in the same direction.

Study on polyester and sperm: blog.planetcare.org/scientists-made-men-switch-from-polyester-to-cotton-underwear-what-happened-next-will-terrify-every-person-wearing-synthetic-clothes More on fertility and fabric chemicals: mrfertyl.com/blogs/naturally-fertyl/polyester-vs-fertility-the-hidden-risks-of-synthetic-fabrics

69% of All Fiber Produced Is Synthetic

This isn't a fringe material. According to the Textile Exchange's 2025 Materials Market Report, synthetic fibers made up 69% of global fiber production in 2024. Polyester alone accounted for 59%, roughly 78 million tonnes. The vast majority of clothing on the market right now is petroleum-based plastic.

When you walk into most clothing stores, you're shopping in a plastic store. The cotton and linen and wool sections are the exception, not the rule. That blew my mind when I first learned it, and it still bothers me every time I walk through a mall.

Report: textileexchange.org/knowledge-center/reports/materials-market-report-2025

What This Means in Practice

I'm not going to tell you to throw out your entire closet. That's not realistic, and it's wasteful. But once you start reading labels, you can't unread them. Here's what shifted for me:

I replaced the things that sit closest to my skin first. Underwear, bras, undershirts, pajamas, workout clothes, base layers. These are high-contact, high-sweat garments where chemical absorption is highest. Organic cotton and merino wool cover most of these categories without costing significantly more.

I stopped buying new synthetics. When something wears out, I replace it with a natural fiber version. Over a year or two, most of my closet turned over naturally.

I started looking at tags the way I look at ingredient lists on food. If it's 100% polyester, I put it back. If it's a blend with more than 50% synthetic, I skip it. Same thing at thrift stores. Natural fiber gems are in there if you're willing to flip tags.

The Bottom Line

There are no massive clinical trials that definitively prove your polyester leggings are causing disease. That research takes decades and billions of dollars, and the textile industry has no incentive to fund it. But the chemicals in synthetic clothing are the same chemicals already flagged as endocrine disruptors, reproductive toxins, and carcinogens through other exposure routes. Your skin is absorbing them. Your sweat is accelerating it.

I'd rather wear cotton. Whitley seems to prefer it too (she kneads the organic cotton blankets way more than the old polyester ones, just saying).

This is the first post in a three-part series on plastic-free clothing. Next up: What Is Polyester, Actually? A Breakdown of the Plastic in Your Closet.

Cailin + Whitley (the cat)