This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Microplastics are plastic particles smaller than 5 millimeters that originate either from manufactured products or from the breakdown of larger plastic items. They can now be found everywhere, from oceans and rivers to soils and indoor air.
Because most plastics degrade very slowly, these particles can remain in the environment for decades or centuries. While larger microplastics can be detected and classified relatively easily, estimates suggest that microplastics larger than 100 micrometers, roughly the thickness of a human hair, represent only about 3% of the total plastic particles present in the environment. However, characterizing particles smaller than 20 micrometers still represents a major challenge.
"We need to be able to detect well below 100 micrometers. Otherwise, we are only observing the tip of the iceberg," explains Christel Hassler, former scientific coordinator at EPFL. To improve the detection of tiny particles, a team led by Hassler and Florian Breider, director of the EPFL Central Environmental Laboratory, has developed a new AI-based technique that can identify and classify six types of polymers—very long molecules made of many small repeating units linked together—in particles as small as 5 micrometers.
Since microplastic abundance increases exponentially as particle size decreases, the results were used to estimate pollution levels for microplastics between 1 and 100 micrometers. The method is published in npj Clean Water. Using water samples from Lake Geneva and its surrounding rivers, the researchers found that concentrations of microplastics measuring between 1 and 100 micrometers may have been underestimated by more than 650-fold.
Evaluations carried out by EMPA show that, of the 38 samples analyzed, about six exceeded the ecotoxicological thresholds used to assess environmental risks. Hassler sees these findings as an important warning sign: "We are not in an alarming situation, but we might be at the threshold where we should worry." The immediate question is whether such high concentrations pose a risk to the population and ecosystems. Although the effects of small microplastics have been extensively studied in laboratory settings, understanding their impact on natural ecosystems remains challenging and requires accurate measurements of environmental concentrations.
"The entire food chain may be exposed to microplastics. In some cases, it is not only the bioaccumulation of plastics but also other substances, such as additives that are transported by them," says Breider. Previous studies estimate that more than 15,000 chemicals are used in plastic manufacturing.
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