However, Min emphasized that this suggests that microplastics are making people sick by generating ROS. While animal studies often suggest that ROS are possible causes of oxidative stress and chronic inflammation, ROS can be produced in many ways, including through basic metabolic activities.
Min admitted that it is quite difficult to compare the magnitude of this effect with the influence of the ROS that our own cells generate.
A local problem
“If you’re really at the interface, you could be significantly affected by this effect, whereas if you’re just a few micrometers away, you won’t feel it,” Min said. Exposure is another unknown here. Min also emphasized that no one can yet say how much microplastic an average person consumes each year through food, water and air.
The plastics used in the study were mostly fresh, lab-bought powders, as opposed to weathered particles we encounter in the environment. In the team’s tests, older particles with more oxidized surfaces produced slightly weaker signals. “This aging process is very heterogeneous,” said Min. “Some microplastic particles were made 50 years ago, others five days ago.” Finally there is the question of size.
Microplastics are generally understood to mean particles that are smaller than five millimeters, with the minimum limit being between 100 and 1,000 nanometers. Min’s team has not tested how varying microplastic particle size affects the chemistry of water interfaces, but the researchers suspect it may play a role. The same mass of plastic broken into nanoparticles has a far larger surface area, potentially making the effect greater. “This could be another reason why nanoplastics are more dangerous,” Min said.
The researchers argue that if water-repellent surfaces affect the chemistry of the water interface, plastics could be designed to be less water-repellent, either by changing their molecular structure or by incorporating additives. But first, the team wants to focus on the question their study left unanswered. “We definitely want to see to what extent this effect directly contributes to disease or biological problems in animals and humans,” Min said.
Nature, 2026. DOI: 10.1038/s41586-026-11141-y
