How textile colour accelerates ocean microplastic pollution

A growing body of scientific research is beginning to quantify what the fashion industry has long suspected: synthetic clothing, particularly polyester, is one of the major sources of microplastic pollution in the world’s oceans. Now, a new paper by Chen R., Zhao X. and colleagues at the Nanjing University of Information Science and Technology, published in Marine Pollution Bulletin, shows that fabric colour itself may accelerate the process.

The study simulated sunlight exposure in coastal seawater, revealing that darker PET (polyethylene terephthalate) textiles, especially purple and green, broke down faster and released more microfibres than lighter shades such as yellow or blue. Over a 12-day experiment mimicking one year of natural sunlight, just 0.1 grams of PET fabric released up to 47,000 fibres.

The reason lies in physics: darker dyes absorb more ultraviolet light, producing reactive oxygen species that weaken polymer chains, leading to faster fragmentation. This makes black, purple and deep green textiles disproportionately polluting, a finding that could reshape how manufacturers assess the sustainability of coloured synthetic fabrics.

Globally, between 20 and 53 million tonnes of plastic waste enter the oceans each year, according to UN-linked estimates. The majority of textile microfibres come from polyester, which accounts for roughly 60 percent of global fibre production. A single domestic laundry cycle can release around 700,000 microfibres, many of which bypass filtration systems and enter rivers and seas.

Design compliance

For fashion and homeware brands, this introduces a new design and compliance question. As microfibre regulation gathers pace, with France’s 2025 filter mandate and the EU’s Ecodesign for Sustainable Products Regulation on the horizon, the chemical profile of dyes and the physical behaviour of fabrics under sunlight will soon matter as much as their carbon footprint.

“Colour is not just an aesthetic choice, it’s a chemical one,” the authors note. Their findings suggest that textile producers and dye manufacturers may need to prioritise low-UV-reactive dyes and re-engineer synthetic yarns to resist photo-oxidation.

Beyond compliance, there is a reputational imperative. As sustainability becomes an investment-driven metric, major groups from Inditex to Kering have already begun mapping their microfibre emissions. For luxury and performance brands alike, material innovation — from solution-dyed fibres to bio-based coatings, could become a differentiating factor in the decade ahead.

The research underscores a shift in how environmental risk is being defined in fashion. It is no longer simply about where materials come from, but what happens to them long after the garment is worn, washed, or discarded.

Article source: Chen R., Zhao X., Wu X., Wang X., Wang J. & Liang W. (2024). Sunlight-Driven Photochemical Transformation of Colored PET Textiles to Microfibers in Coastal Seawater, Nanjing University of Information Science and Technology.