Our clothes are polluting the ocean with tiny plastic microfibres every time they are washed – that’s the finding from a team of investigators who tested synthetic clothing from four major fashion brands.

Some of the synthetic clothing with high polyester content that the researchers tested released so many microfibres per wash that the garments disintegrated after just a few washes.

A tested blouse from Zara lost an average of 307.6 milligram of fibres per kilogram of laundry. 100% polyester t-shirts from both Adidas and Nike lost a very similar percentage of fibres per wash: 124,05 mg/kg and 125 mg/kg, respectively. An H&M blouse that was tested contained 65% recycled polyester and it lost an average of 48,6 mg per kg of wash.

Maria Westerbos, Director and Founder of the Plastic Soup Foundation – one of the groups behind the research – said:

This is what you call fast fashion. It disappears in front of your eyes.

Westerbos added that: “Although the outcome is very worrying and three out of the four fashion brands perform ‘badly’, we cannot completely compare them. It all depends on what fabric has been used and how the yarn is made: what (combination) of materials, but also if it the fibers are long or short, or if the yarn is woven or knitted. We need a benchmark to be able to compare yarn, but no fashion brand in the world is really willing to stick out its neck.

Over the last 20 years, demand for polyester has grown faster than demand for wool, cotton and other fibres. By 2030 synthetics are expected to account for 75 percent of global apparel fibre production. An average 6kg washing machine load can release an estimated 700,000 microscopic plastic fibres into the environment.

A major aspect to the microfibre pollution problem is that regular washing machines are not capable of filtering out microfibres and ‘upstream’ solutions are still in development. Recent European Commission-funded research saw the development of a pectin coating that can be added to yarn which could potentially prevent more than 80% of microfibre release.

Awareness of the microfibre problem first emerged back in 2004 when researchers from the University of Plymouth in the United Kingdom set out to investigate the occurrence of microplastics in the marine environment. They found an increase in fibrous synthetic material over time that corresponded with the onset of synthetic fibre production in the 1970s.

In 2011, scientists found that microfibres made up 85% of human-made debris on shorelines around the world, with evidence of textile-derived microfibre pollution cropping up as far away as the Antarctic. A study published this January showed that nylon made up more than 60% of the microplastics that are widely ingested by marine mammals off the British coast with clothing microfibres one of the possible sources alongside fishing net and toothbrush bristles.

Just last week the EU moved to use its powerful chemical laws to stop most microplastics and microbeads being added to cosmetics, paints, detergents, some farm, medical and other products. The restriction is expected to become law across Europe by 2020.

While there has been political action to tackle the impact of microbeads from cosmetics, some researchers estimate that the sheer quantity of microplastic washed into rivers, lakes, and seas when synthetic clothing such as polyester and nylon is thrown in the wash could be a far greater environmental threat.