Bio: Dr. Raymond Pieters is Associate Professor at the Institute for Risk Assessment Sciences (IRAS) of Utrecht University (Faculty of Veterinary Medicine), and Professor in Innovative Testing in Life Sciences & Chemistry at University of Applied Sciences Utrecht (UASU, Hogeschool Utrecht). His research focuses on assessment of effects of substances (e.g. drugs, proteins, pollutants and microplastics) on inflammatory processes in relation to allergic diseases. Currently, he is particularly working on intestinal immune effects by using test animal-free approaches, e.g. stem cell organoids. He is involved in various national (TTW, RAAK, ZONMW, NWO) and international (EU-IMI, EFRO, NC3R, EC-HORIZON) projects, moste relevant the EC-HORIZON POLYRISK project.  

Abstract: The presence of micro- and nanoplastic particles (MNP) in our environment has raised increasing public and political concern. Evidence suggests that humans are exposed to these MNP, mostly via inhalation or ingestion. The EC-Horizon project POLYRISK (https://polyrisk.science) aims to establish an IATA/AOP-based tiered approach to assess human health risks of MNP. In our research, we focus on assessing immunotoxicological effects of MNP via inhalation and ingestion. In vitro studies have shown that many MNP (commercial PS, secondary PVC, PA, PP and PE at 10 or 100 µg/ml) decrease viability of macrophages, but they do not activate pro-inflammatory responses. Only secondary PP and PE with oxidized surface groups increase NF-κB expression and release of cytokines. Human in vivo studies using a controlled traffic exposure scenario show that short term inhalation exposure induces increases of leukocytes (in particular monocytes) in blood. In conclusion, of environmentally relevant MNP (MNP with active surface groups or environmental components, or traffic-related MNP) appeared to be immunostimulatory, whereas primary and secondary MNP rather reduce macrophage activity and viability (at relatively high concentrations of 100 µg/ml). Further research is needed how to translate these findings to human health risk assessments.

Acknowledgement: This research is funded by the EC Horizon 2020-project POLYRISK [Grant ID 964766] and the ZonMw/Health Holland project MOMENTUM [Grant ID 458001101].