The polyester problem: what we're really wearing against our skin

For a long time, the working assumption was simple: skin is a barrier. What touches it stays outside it. That assumption is being quietly dismantled by a small but growing body of research into what happens when synthetic fabric meets sweat.

The skin is not a wall

In April 2024, researchers at the University of Birmingham published the first experimental evidence that chemicals used as plastic additives — flame retardants, in this case — can leach out of microplastics and into human sweat, where they become available for absorption straight through the skin and into the bloodstream.

Using 3D human skin models, the team found that as much as 8% of the chemical present could be taken up by the skin over a 24-hour exposure window. Critically, more hydrated — sweatier — skin absorbed significantly more than dry skin did.

Where the microplastics actually come from

Polyester, nylon, and acrylic are not fabrics in the way cotton or linen are fabrics. They are plastic, drawn into fibre form. Every wash sheds them: a single load of polyester laundry can release several hundred thousand microscopic fibres into wastewater, many of which end up in rivers, oceans, and — eventually — back in the food chain.

But washing isn’t the only source of shedding. Heat, movement, and friction against skin all do the same thing on a smaller scale, continuously, while the garment is being worn.

The bigger picture: microplastics in the body

Separately from the clothing research, microplastics have now been detected in human blood, lungs, liver, placenta, and breast milk. A 2024 systematic review published in BJOG, a leading obstetrics and gynaecology journal, examined the growing evidence for microplastics’ presence in reproductive tissue and called for more research into their effects on human fertility.

It’s important to be precise here: these studies are documenting that microplastics from all sources — food packaging, water, air, textiles, and more — are accumulating in the body. The research has not yet drawn a direct, isolated line from “wearing polyester” to a specific change in fertility or breast milk.

Why we build with organic cotton

This is the case for the decision we made at the very start of Boutique Kaotique: every BoKa garment is made from 100% organic cotton, 180gsm, made-to-order.

Cotton is not a plastic. It doesn’t shed microfibres into your bloodstream when you sweat in it. It doesn’t carry flame retardants, plasticisers, or disperse dyes that leach more readily under heat and moisture. It’s a fibre your skin has known how to interact with for thousands of years, not a polymer your body is still learning to process.

We’re not claiming organic cotton eliminates every form of chemical exposure — no textile exists in a vacuum. But choosing it over polyester removes an entire category of exposure described above: the steady, cumulative, skin-level absorption of plastic particles and their additive chemicals, intensified by the very thing your body does naturally when it works hard — sweating.

What this means for what you wear

You don’t need to throw out every synthetic item you own overnight. But it’s worth being intentional about the categories of clothing that spend the most time against sweating, exposed skin — activewear, underwear, sleepwear, anything fitted and worn for hours at a stretch — and choosing natural fibres there first.

That’s the principle behind every piece we make. Organic cotton, grown without synthetic pesticides, woven into clothing that’s made only once it’s ordered, worn against skin that deserves better than what most fast fashion currently offers it.

We started Boutique Kaotique because the fashion industry’s relationship with waste and synthetic material felt fundamentally broken. The research keeps confirming why that mattered in the first place.