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Washing Clothes Releases More Than Just Microplastics

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Credit: Sarah Brown / Unsplash.
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When clothes made from synthetic fibers are washed, they release tiny fragments of plastic into the water. Depending on the type of garments being washed, studies have shown that a single load of laundry can release up to 1.5 million synthetic microfibers into the waterways.

This release of micro- and nanoplastics from textiles is a significant source of plastic pollution in our oceans. But what if some of these nanoplastics weren’t nanoplastics at all?

New analysis by researchers at the Swiss Federal Laboratories for Materials Science and Technology (EMPA) suggests that some of the supposed nanoplastics released during textile washing are not nanoplastics, but are actually clumps of water-insoluble oligomer molecules. The research is published in Nature Water.

Little is known about the toxicity or potential health effects of exposure to these oligomers, the researchers warn.

Washing clothes releases nanoparticulate oligomers

Studying 12 different types of polyester fabrics, including microfiber, satin and jersey samples, the researchers washed each sample up to 4 times and examined what particles were released by the fabrics.

This is no easy task, as tiny plastic particles are all around us. "Plastic, especially nanoplastics, is everywhere, including on our devices and utensils," said study author Bernd Nowack, leader of the Environmental Risk Assessment and Management Group at EMPA. "When measuring nanoplastics, we have to take this 'background noise' into account."

To distinguish between plastic nanoparticles and other background noise, the researchers rinsed the particles they recovered in ethanol solvent. Plastic particles, whether they are micro- or nano-sized, do not dissolve in ethanol.

After the ethanol rinse, the researchers found that between 34–89% of the nanoparticles isolated from the fabric washing experiments were soluble in ethanol, meaning that they were not true nanoplastics.

"This allowed us to show that not everything that looks like nanoplastics at first glance is in fact nanoplastics," Nowack said.

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Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, alongside scanning TEM energy-dispersive X-ray (STEM-EDX) analysis, the researchers were able to study the morphology and elemental composition of the unknown particles.

They concluded that the most likely explanation for these water-insoluble, ethanol-soluble particles was that they were small clusters of polyethylene terephthalate (PET) oligomers. Oligomers are medium-sized polymer molecules consisting of relatively few repeating monomer units. PET oligomers are known to be soluble in ethanol.

How concerning are these particles?

The mechanism through which these particles are released from textiles is still unclear, for both nanoplastics and oligomer clusters. However, the researchers found that the number of particles released did appear to decrease significantly with repeated washes. The nature of the textile and the cutting method used to make the fabric samples – scissors or laser cutting – also had no major impact on the quantity of particles produced.

The researchers suggest that these oligomer particles might be created during the manufacturing of the textiles or alternatively, they could be the result of chemical processes taking place during storage.

The effect that these oligomers might have on the environment and human health is also unknown, though it is a concern. "With other plastics, studies have already shown that nanoparticulate oligomers are more toxic than nanoplastics," said Nowack. "This is an indication that this should be investigated more closely."

Nowack and his team plan to continue to study the release of fibers from textiles – this time from fabrics made with renewable raw materials.

"Semi-synthetic textiles such as viscose or lyocell are being touted as a replacement for polyester," Nowack said. "But we don't yet know whether they are really better when it comes to releasing fibers."

Reference: Yang T, Xu Y, Liu G, Nowack B. Oligomers are a major fraction of the submicrometre particles released during washing of polyester textiles. Nat Water. 2024;2(2):151-160. doi:10.1038/s44221-023-00191-5

This article is a rework of a press release issued by Empa. Material has been edited for length and content.