Regulatory relevance of the EU Research Cluster to understand the health impacts of micro and nano plastics (CUSP) Micro- and nanoplastics: substances of public health concern? The presence of micro and nanoplastics (MNPs) is part of our everyday life and they find their way into our bodies through the air we breathe, the water we drink and the food we eat. It is not known how MNPs might be affecting human health. Policymakers and regulatory authorities around the world are increasingly implementing regulatory measures to address this concern. For instance, policymakers in the EU have adopted the Single-use Plastics Directive to reduce the environmental impact of certain forms of plastics used once or for a very limited period of time, such as straws, cutlery, plates, cotton swabs and balloon sticks1. Early in 2021, the European Commission funded five large-scale research projects under the European Union’s Horizon 2020 research and innovation programme (see figure 1) and united them under the European Research Cluster to Understand the Health Impacts of Micro-and Nanoplastics (CUSP) (see https://cusp-research.eu). In total, CUSP unites a multidisciplinary team of scientists, industries, and policymakers from 75 organisations across 21 countries. The five projects collaborate in understanding exposure routes; in assessment of hazard and risk; in developing new analytical tools, in data-sharing, in inter-laboratory comparisons, and in communicating and disseminating research results. By establishing six CUSP working groups, our synergies seek to amplify the efforts of individual projects. The close collaboration with the European Commission’s Joint Research Centre (JRC) and a constant dialogue between scientists, stakeholders and policymakers will enhance the policy relevance and impact of the research.