New study reveals dark-colored polyester fabrics release more micro-plastics under sunlight

A growing number of studies are confirming what the fashion industry has long suspected — synthetic clothing, especially polyester, is one of the biggest sources of microplastic pollution in the oceans. Now, new research from Nanjing University of Information Science and Technology suggests that the colour of the fabric might also influence how much plastic ends up in the sea.

Published in Marine Pollution Bulletin, the study by Chen R., Zhao X., and colleagues found that darker polyester fabrics, particularly purple and green, degrade faster under sunlight and release more microfibres than lighter shades like yellow or blue. The researchers simulated sunlight exposure in coastal seawater, representing a full year of natural light within 12 days. During this period, just 0.1 grams of PET (polyethylene terephthalate) fabric released up to 47,000 tiny fibres.

The reason lies in how colours absorb light. Darker dyes soak up more ultraviolet rays, which generate reactive oxygen molecules. These molecules weaken the plastic’s structure, making it easier for the fabric to fragment. As a result, dark synthetic textiles could be responsible for a higher share of microplastic pollution than previously thought.

This adds a new layer of complexity for designers and manufacturers. With regulations on microfibre release gaining momentum — such as France’s upcoming 2025 washing machine filter rule and the EU’s Ecodesign for Sustainable Products Regulation — fabric colour and dye chemistry are becoming environmental factors in their own right.

The researchers put it simply: “Colour is not just an aesthetic choice, it’s a chemical one.” Textile and dye producers may need to focus on less UV-reactive dyes and develop synthetic fibres that resist sunlight-induced degradation.

Globally, an estimated 20 to 53 million tonnes of plastic waste enter the oceans every year. Polyester, which makes up around 60 percent of all fibres produced, is a major contributor. A single household wash can release up to 700,000 microfibres — many of which escape filtration systems and reach rivers and seas.

For brands, this isn’t only a compliance issue but also a reputational one. Major groups like Inditex and Kering are already tracking their microfibre emissions and investing in material innovations such as solution-dyed fibres and bio-based coatings.

The findings highlight how sustainability in fashion is evolving. It’s no longer just about where materials come from but also about what happens after the garment’s life — when sunlight, water, and time start to break it down.

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.