You turn over the tag on a new pair of leggings and there it is: the OEKO-TEX logo, small and green, next to 88% polyester, 12% elastane. It feels like a promise. So does OEKO-TEX mean no microplastics? No. OEKO-TEX STANDARD 100 tests a garment for harmful chemicals. It doesn't test the fiber, and it doesn't measure the tiny plastic threads a synthetic garment sheds. Those leggings can be certified and still be plastic.
The label is doing its job. Nobody explains where that job ends.
Two questions, one logo
When people worry about what's in their clothes, they're usually asking two separate things.
The first is about chemicals: the dyes, finishes and treatments added to fabric in the factory. Formaldehyde to stop wrinkles. PFAS to repel water. Heavy metals hiding in color.
The second is about the fiber itself. Polyester, nylon, acrylic and elastane are plastics, spun into thread. As you wash and wear them, they break off into microplastics, which scientists define as pieces of plastic smaller than five millimeters, about the width of a pencil eraser.
OEKO-TEX was built to answer the first question, and it answers it well. There's no common label for the second one. Your food has an ingredient list and your water has federal limits. The fabric against your skin all day has neither for this, so a reassuring logo ends up doing a job it was never designed to do. A bill introduced in Congress in November 2026 would add one: the Clothing Microplastic Transparency Act would put an estimated microplastic number on every clothing tag.
What OEKO-TEX actually checks
OEKO-TEX STANDARD 100 is the label most people mean when they say "OEKO-TEX certified." According to OEKO-TEX, every part of a certified product, every thread, button and accessory, is lab-tested against a list of over 1,000 harmful substances. Products only pass if they come in under the limits.
The rules get stricter the closer something sits to your body. Baby clothes face the toughest limits, followed by things worn against the skin, like underwear, shirts and sheets. Certificates last one year, and products are tested again to renew. It's one of the most rigorous chemical checks a garment can get, and if you want to see the full list of what it covers, our OEKO-TEX guide walks through it.
What the logo can't show you is that STANDARD 100 has no rules about fiber type. Cotton can pass. Linen can pass. A 100% polyester shirt can pass too, as long as every component stays under the chemical limits.
OEKO-TEX hasn't ignored microplastics entirely. In its 2024 update, the organization required factories certified under STeP, its separate certificate for production sites, to find and reduce the microplastics they release during manufacturing. In 2025, it put microplastics from glitter under observation for STANDARD 100.
Both are real steps. Neither one measures what a finished garment sheds once it's yours.
- Harmful chemicals Tested
- Fiber type Not tested
- Fibers it sheds Not tested
- Harmful chemicals Tested
- Factory microplastic release Covered
- Fibers it sheds Not tested
How much a garment sheds
The shedding is easy to underestimate because you can't see it. Researchers at the University of Plymouth tried to count it. In a 2016 study published in Marine Pollution Bulletin, Imogen Napper and Richard Thompson washed different synthetic fabrics and filtered what came out. They estimated that a typical 6-kilogram load could release more than 496,000 fibers from polyester and more than 728,000 from acrylic.
That's one load of laundry.
Washing isn't the only moment it happens. A 2020 study in Environmental Science & Technology, from researchers in Italy and the same Plymouth team, measured what polyester garments release into the air just from being worn. Over a year, they found the amount shed into the air from wearing was on the same scale as the amount washed down the drain. Simply moving through your day in synthetic clothes is part of the story.
That same study also found that fabric construction matters. The garment that shed the least had a very tight weave made from long, tightly twisted threads. So not all synthetics behave the same, but all of them are still plastic.
The research on what microplastics mean for the human body is still young. What's already clear is where they come from, and that no chemical test on a label is designed to catch them.
What to look for instead
None of this makes OEKO-TEX less worth looking for. It just means you need two checks, not one.
Read the fiber content first. The composition tag answers the microplastics question before any logo does. Cotton, linen, wool, silk and hemp don't shed plastic. Polyester, nylon, acrylic and polyamide do. Recycled polyester is still polyester.
Then read the label. Natural fiber tells you what the thread is, not what was added to it. Cotton can still be dyed and finished with harsh chemicals, which is exactly where OEKO-TEX STANDARD 100 or GOTS (the Global Organic Textile Standard, which covers organic fiber and how it's processed) earns its place. Natural fiber and a real certificate together answer both questions.
Check that the label is real. Every STANDARD 100 label has a certificate number. Type it into OEKO-TEX's free Label Check to confirm it's valid and covers the kind of product you're holding. If you'd like the factory side covered too, MADE IN GREEN by OEKO-TEX combines a STANDARD 100 product with STeP-certified production. Looking for a seal is one of five ways to check if your clothes contain harmful chemicals.
Be realistic about stretch. A legging at 95% cotton and 5% elastane is a cotton legging. A small percentage of stretch is a very different thing from a garment that's mostly plastic, and you don't need perfection to make a real difference.
Start where contact is longest. If you're swapping slowly, begin with what sits on your skin for hours: underwear, pajamas, sheets and the leggings you live in. We've written more about what wearing polyester all day does if you want to go deeper.
Reading past the logo
A certification is only as useful as your understanding of what it promises. OEKO-TEX promises a garment was tested for harmful chemicals, and that promise holds. It never promised the garment wasn't plastic.
The clothes you wear are a health choice, the same way your food is. You don't need to throw out everything you own. You need to read two lines on a tag instead of one, and you already know how.
Frequently asked
No. An OEKO-TEX label means the product was tested for harmful chemicals. It says nothing about whether the fiber is plastic. A 100% polyester garment can be certified, and it still sheds plastic fibers when you wash and wear it.
Not for the fibers a garment sheds. OEKO-TEX STANDARD 100 tests the finished product for over 1,000 harmful substances, like formaldehyde, banned dyes, heavy metals and PFAS. In 2025, OEKO-TEX put microplastics from glitter under observation, but there's no test for how much plastic fiber a shirt or legging releases.
Yes. STANDARD 100 has no rules about fiber type. A 100% polyester garment can carry the label as long as every part of it passes the chemical limits.
It means the polyester and everything on it tested below the limits for over 1,000 harmful substances, which is a real step up from an untested garment. It doesn't change what the fiber is. OEKO-TEX polyester is still plastic, and it still sheds plastic fibers when you wash and wear it.
OEKO-TEX STeP, the certificate for factories, has required certified facilities to manage and reduce the microplastics they release during manufacturing since 2024. That covers the factory floor, not the garment once it's in your closet.
Read the fiber content before the logo. Clothes made from 100% natural fibers like cotton, linen, wool, silk or hemp don't shed plastic. Then use OEKO-TEX or GOTS to check what was added to those fibers during dyeing and finishing.
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