Some of the supposed nanoplastics shed during washing of clothes made of synthetic fibres do not actually consist of plastic particles, but of water-insoluble oligomers. The effects they have on humans and the environment are not yet well-understood.
- Researchers have found that to a considerable extent the released particles were in fact not nanoplastics, but clumps of so-called oligomers, i.e. small to medium-sized molecules that represent an intermediate stage between the long-chained polymers and their individual building blocks, the monomers.
- These molecules are even smaller than nanoplastic particles, and hardly anything is known about their toxicity either.
THE RESEARCH: The findings come from a study conducted by researchers at EMPA (Swiss Federal Laboratories for Materials Science and Technology) in association with colleagues from China who wanted to take a closer look at nanoparticles released from textiles.
- Tong Yang, first author of the study, carried out the investigations during his doctorate at EMPA. In earlier studies, EMPA researchers were already able to demonstrate that both micro- and nanoplastics are released when polyester is washed.
- A detailed examination of the released nanoparticles released has now shown that not everything that appears to be nanoplastic at first glance actually is nanoplastic.
- The researchers published their findings in the journal Nature Water.
THE SIGNIFICANCE: Plastic household items and clothing made of synthetic fibres release microplastics: particles less than five millimetres in size that can enter the environment unnoticed.
- A small proportion of these particles are so small that they are measured in nanometers. Such nanoplastics are the subject of intensive research, as nanoplastic particles can be absorbed into the human body due to their small size—but, as of today, little is known about their potential toxicity.
WHAT THE RESEARCHERS DID: The researchers examined twelve different polyester fabrics, including microfibre, satin and jersey. The fabric samples were washed up to four times and the nanoparticles released in the process were analysed and characterised.
- This was not an easy task since plastic, especially nanoplastics, is everywhere, including on our devices and utensils. When measuring nanoplastics, the researchers had to take this 'background noise' into account.
- Then they used an ethanol bath to distinguish nanoplastics from clumps of oligomers. Plastic pieces, no matter how small, do not dissolve in ethanol, but aggregations of oligomers do. The result: Around a third to almost 90% of the nanoparticles released during washing could be dissolved in ethanol. This allowed them to show that not everything that looks like nanoplastics at first glance is in fact nanoplastics.
What they said:
With other plastics, studies have already shown that nanoparticulate oligomers are more toxic than nanoplastics. This is an indication that this should be investigated more closely
— Bernd Nowack
Research scientist
Swiss Federal Laboratories for Materials Testing and Research (EMPA)
