Textiles Research note 02 Confidence: good, with caveats

Where ocean microplastics really come from.

"A third of ocean microplastics come from our clothes." It's the number on our homepage — so here is exactly where it comes from, and the asterisks the headline leaves off.

By the Vorus desk ~6 min read Last read: 2026

Microplastics split into two kinds. Secondary microplastics are big plastics — bottles, bags, nets — broken down by sun and waves over years. Primary microplastics enter the water already small. The figure we quote is about the second kind, and it's the one your wardrobe touches.

The 35% number

In 2017 the IUCN modelled the sources of primary microplastics reaching the ocean. The single largest category, at roughly 35%, was synthetic textiles — tiny plastic fibres shed mostly during laundry.1 Polyester, nylon, acrylic and elastane are plastics spun into thread; every wash abrades them and rinses the fragments down the drain.

Read the small print That 35% is a share of primary microplastics in one global model — not "35% of all ocean plastic." Models like this carry wide uncertainty bands. We quote it because it's the best available estimate, not because it's gospel.

700,000 fibres a wash

The household end of this was measured directly. Napper and Thompson (2016) washed synthetic garments and counted what came off: a single 6 kg load could release on the order of 700,000 microfibres, varying by fabric and wash settings.2 Acrylic shed the most; polyester-cotton blends the least of the synthetics tested. Wastewater plants catch a lot of this, but not all — and the captured sludge often ends up on farmland anyway.

So is "natural fibre" the fix?

Partly, and we won't oversell it. The honest version:

  • Natural fibres still shed. Cotton, wool and linen release fibres in the wash too. The difference is what those fibres are: cellulose and protein that biodegrade, versus plastic that persists for decades.3
  • "Persistence" is the real variable. A cotton thread in seawater breaks down over months; a polyester one is still a polyester one. So the load that accumulates is dominated by synthetics.
  • Dyes and finishes complicate it. A "natural" fibre drowned in synthetic coatings isn't as clean as the label implies — which is why the material is necessary but not sufficient. We look at the whole make-up, not just the headline fibre.

The bottom line

Synthetic textiles are the biggest single source of primary ocean microplastics, and your washing machine is part of the pipe. Choosing natural fibres doesn't stop shedding — it changes what sheds into something that breaks down instead of building up. That's the case for the natural-fibre basics we're sourcing: cotton and linen, minimal synthetic finishing, and honesty about the bits a single fibre choice can't solve.

Sources

  1. Boucher J, Friot D. Primary Microplastics in the Oceans: a Global Evaluation of Sources. IUCN, 2017.
  2. Napper IE, Thompson RC. Release of synthetic microplastic plastic fibres from domestic washing machines. Marine Pollution Bulletin, 2016.
  3. Reviews on fibre biodegradation in marine and freshwater conditions, comparing cellulosic and synthetic textiles, 2019–2022.

Figures are modelled estimates with real uncertainty. Citations to be finalised before launch.

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