Micro- and nanoplastics are now popping up everywhere: in seawater, snow, food, and even in our bodies. The very smallest particles, in particular, are difficult to measure, meaning we still know too little about their spread and associated risks. UvA chemist Maria Hayder and her colleagues have developed a new measurement method that maps nanoplastics in water and the environment much more accurately. On Wednesday, 24 June, she will defend her PhD dissertation on this research at the University of Amsterdam.
Much plastic waste, of which millions of tons are produced annually, breaks down into increasingly smaller particles: microplastics and ultimately nanoplastics. Microplastics are particles between 1 micrometer and 5 millimeters; nanoplastics are even smaller, from 1 nanometer to 1 micrometer.
It is these minuscule particles that are a cause for concern, because they end up in water and food, and thus eventually in our bodies as well.
Combining two techniques
It is particularly difficult to accurately determine the amount of nanoplastics in the environment because they are so tiny and also behave differently from microplastics. ‘Many techniques are already used for microplastics, but they usually don’t work for nanoplastics,’ says Hayder.
To achieve a more reliable measurement, Hayder combined two complementary techniques: one for separating the plastic particles by size and one for chemically recognising and measuring the different types of plastic.
This new method proved capable of identifying and quantifying specific nanoplastics in wastewater.
No simple pattern
The new method was immediately deployed to discover how everyday plastics, which the researchers had exposed to fresh and seawater for years, break down into increasingly smaller particles.
‘We found the nanoplastics in both fresh and seawater,’ says Hayder. Remarkably, the plastic particles did not break down according to a simple "increasingly smaller" pattern but were present in all sorts of different sizes and also appeared at all depths regardless of their density.
Especially common in food
Hayder also examined what is currently known about plastic particles in our food and drinks. ‘Quite a bit of research has been done on seafood, while other important components of our diet – such as fruit, vegetables and grains – have received less attention.’ Yet the researchers estimate the highest daily intake for precisely those food types.
‘We mainly see the commonly used plastics, such as packaging plastic,’ says Hayder. ‘But how you measure largely determines what you find – and that makes studies difficult to compare.’
What happens in our gastrointestinal tract?
And what actually happens if we swallow the plastic particles via water and food and they enter our gastrointestinal tract? To find out, the researchers recreated the digestive process in the lab and subjected plastic particles of various sizes and with diverse properties to it.
‘In the gastrointestinal tract, small particles clump together into larger lumps, mainly due to the action of digestive enzymes. As a result, they become larger and the chance of them passing through the intestinal wall and entering the body is reduced, although this research shows that we still have much to learn about that,’ says Hayder.
Better measurements desperately needed
Better measurements to properly assess the health risks of plastic pollution are sorely needed. ‘Currently, measurement methods vary widely between laboratories, making results difficult to compare. This hinders not only scientific research but also policy regarding plastic use and pollution,’ says Hayder.
‘Our approach is not yet perfect, but it is a good step towards much more precise measurements of nanoplastics in the future. This will be crucial in helping us estimate their spread and potential health risks.’
Thesis details
Maria Hayder, 2026, 'Analytical approaches for studying occurrence and fate of environmental micro- and nanoplastics'. Supervisors: Prof. G.J.M. Gruter and Prof. A.P. van Wezel. Co-supervisors: Dr A. Astefanei and Dr C. Angelici.