In the summer of 2023, Utrecht’s Wilhelmina Park featured volunteers cycling on stationary exercise bikes as part of a scientific study. The goal was to examine the body’s reaction to pollution by analyzing changes in cyclists’ blood caused by exposure to microplastics in the air. These microplastics, which come from sources like tire wear and plastic decomposition, are prevalent globally. The Dutch study indicated that short-term exposure can temporarily affect the immune system, though long-term impacts remain uncertain.
Dr. Raymond Pieters from Utrecht University noted the unknown long-term effects of continuous exposure. He led the POLYRISK project, part of a broader EU research initiative concluding in 2025, aimed at understanding how micro- and nanoplastics (MNPs) enter the body and impact the immune system. With significant volumes of microplastics released annually into the environment, there’s a push to reduce pollution by 30% by 2030.
Alba Hernández from the Autonomous University of Barcelona highlighted exposure through food, water, and air, though the primary harmful route is still unknown. Her work with the PLASTICHEAL project revealed early signs of inflammation and DNA damage from MNPs, raising concerns over potential long-term health impacts, including chronic diseases like cancer.
Microplastics can also carry toxins, heavy metals, and pathogens, posing an indirect risk via the “Trojan horse” effect. The smallest particles, once inhaled or ingested, may get absorbed by immune cells but remain undigested, potentially accumulating in organs such as the liver or kidneys.
The EU supports research efforts under the European Research Cluster to Understand the Health Impacts of Micro- and Nanoplastics (CUSP), with initiatives examining microplastics’ health effects from various angles. The PlasticsFatE project, for example, used lab models to study particle behavior in the body, suggesting that some may breach the gut barrier and enter the bloodstream.
Measuring exposure levels remains challenging due to the diversity of plastics and their varying behaviors. Some experts, like Mark Morrison from PlasticsFatE, argue that transported substances might be more harmful than the plastics themselves.
Despite uncertainties, researchers advocate for immediate action to reduce microplastic exposure, as reflected in a 2025 roadmap from CUSP outlining key knowledge gaps and future research priorities. Reducing current exposure could mitigate potential future risks.
This research was supported by the EU’s Horizon Programme, with interviewee views not necessarily reflecting those of the European Commission. For more information on CUSP initiatives, revisit the 2022 article ‘We eat and inhale thousands of bits of plastic every year. Now what?’.
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