What is Polyester & Why is it Bad

Polyester is in almost everything right now. Leggings, blouses, dresses, activewear. It's cheap, it's everywhere, and the fashion industry loves it. But once you understand what it actually is and what it's doing to your body, it's hard to look at your closet the same way.

Polyester is plastic. Literally.

Polyester is a synthetic fiber made from petroleum, the same stuff that makes plastic bottles. It was engineered to be cheap and durable, not to be kind to your skin or the planet. The fashion industry adopted it en masse because it cuts manufacturing costs. Your comfort and health were not really part of the equation.

It suffocates your skin

Natural fibers breathe. Polyester doesn't. It traps heat and moisture against your body, creating a warm, bacteria-friendly environment that leads to odor, irritation, and breakouts, especially in sensitive areas. Ever noticed a polyester shirt smelling worse faster than a cotton one? That's why.

It may be messing with your hormones

This is where it gets harder to ignore. Polyester fabrics are commonly treated with chemicals like phthalates and BPA during production and dyeing. These chemicals don't just sit on the surface of the fabric. They migrate through the skin, especially when heat, friction, and sweat are involved — which, if you're wearing activewear, is pretty much always.

Phthalates are well-documented endocrine disruptors. Research has linked them to decreased testosterone, irregular ovulation, menstrual problems, and reduced sperm quality. A 2024 review of over 120 studies on clothing found widespread phthalate contamination in synthetic garments. A separate study published in Environmental Health Perspectives found that men with higher phthalate levels had measurably lower testosterone and reduced fertility markers.

It doesn't stop there. A 2023 report by the Center for Environmental Health found that some major activewear brands had BPA levels in their sports bras and leggings up to 40 times the recognized safe limit. That's not a trace amount. That's a daily, skin-contact dose of a known hormone disruptor.

The fertility research is real

Studies going back to the early 1990s raised flags about polyester and reproductive health. Research published in Urology Research found that men wearing polyester against the skin experienced significant drops in sperm count and motility. A study in the Journal of Obstetrics and Gynecology found that female subjects wearing polyester showed decreased progesterone levels and reduced ability to conceive. When the polyester was removed, both sperm quality and hormone levels largely normalized, suggesting the effects weren't permanent but were directly tied to the fabric exposure.

More recently, microplastics shed by synthetic clothing have been found in human semen, ovarian follicular fluid, and placental tissue, raising serious questions about what chronic low-level exposure is doing to reproductive health over time.

It sheds plastic into your body every wash

Every time polyester goes through the wash, it releases hundreds of thousands of microplastic fibers into the water. These pass through treatment facilities, enter waterways, and work their way up the food chain. Microplastics have now been found in human blood, lung tissue, and breast milk. We are literally eating and breathing our synthetic wardrobes.

Does that mean all clothes have to be boring looking?

Not necessarily. Recently there has been a wave of brands choosing sustainable fabric while still being cute! At NATRL, our pieces are built on natural foundations: cotton, linen, hemp. Where we add a touch of spandex, it's minimal and intentional, just enough to move with your body, nothing more. A small amount of spandex, 5% or less, used purely for fit and movement is a very different thing from a 100% polyester garment.