Evaluating the microplastic risk
Although it is generally accepted that micro- and nanoplastic particles (MNPs) are ubiquitously present in our everyday lives, what scientists don’t know is what impact these particles have on our health. “How many of these plastic particles are actually being absorbed into our bodies via inhalation and ingestion, and could tiny MNPs inside our bodies have a negative impact on our health? – these are the questions that puzzle scientists,” says Raymond Pieters, a researcher at Utrecht University. Helping to answer these questions is the EU-funded POLYRISK(opens in new window) project. “The project explores these questions by examining human exposure to MNPs and their potential toxic effects, with a special emphasis on the potential adverse effects MNPs have on the immune system,” adds Pieters, who served as the project coordinator.
Measuring microplastic and nanoplastic particles
Bringing together an interdisciplinary team of Europe’s top laboratories and risk assessors, the project used advanced methods to chemically detect and quantify plastic particles, understand the key mechanisms of MNP toxicity and identify biomarkers of toxicity. “One of the key outcomes of the project was understanding how we can best measure MNPs, which has opened the door to being able to test MNPs in complex matrices like blood and air samples,” explains Pieters. For example, in the project’s human scenario studies, rubber-related MNPs, such as those coming from tyres, were abundant in all tested situations, including traffic, textile manufacturing and indoor rubberised football pitches. However, in the real world, such MNPs are only a minor part of all particulates found in the air. “This is important because if a specific exposure is low, potential toxicity will not come into play and, because we already have regulations on air pollution, these may be sufficient to regulate MNP presence in air,” remarks Pieters.
How exposure to microplastics affects human health
But the project did more than just measure MNP exposure, it also looked at the effect MNPs may have on the immune system. For instance, data derived from animal-free testing methods indicate that aged and weathered MNPs tend to have a significant impact on those immune system cells involved in inducing inflammation. Furthermore, stimulatory effects of tyre wear-related MNPs were found in a traffic-related scenario study, showing increased levels of inflammatory leukocytes after short-term exposure. Here, Pieters notes that it is important to realise that ongoing inflammation may exacerbate the effects that MNPs have. “Together, this data shows that MNP exposure can be linked to low to moderate immunological changes, although these changes are temporary,” he says.
A new framework for assessing the microplastic risk
Based on its work, the project has developed an innovative MNP risk assessment framework(opens in new window). The framework, which uses a modular design to organise existing exposure and hazard data and provides the flexibility to adapt it as the science advances, has been well received by health risk institutes in Germany, the Netherlands and Norway, as well as by the Organisation for Economic Co-operation and Development(opens in new window) and the European Food Safety Authority(opens in new window). “Not only were we among the first initiatives to show human data on MNP exposure, our risk assessment framework could lay the groundwork for future studies on how MNP exposure impacts health,” concludes Pieters.
