Challenges in human micro- and nanoplastic risk assessment: stocktaking and the road ahead

Environmental hazards of micro- and nanoplastics (MNPs) and associated chemicals have been investigated for more than a decade. However, the field of human MNPs health risk assessment is still confronted by many uncertainties regarding exposure, fate, as well as the identification of potential health effects. Among others, the lack of reference test MNPs, natural particles as validated reference control, and toxicological test methods that are tailored for MNPs and specifically address the characteristic properties of MNPs, further contribute to data scarcity and hence complicate human risk assessment. Elucidating the complex relationship between MNPs and human health, from early life to adulthood, has been addressed by five European research projects. The aim of these projects organized within the European research cluster to understand the health impacts of MNPs (CUSP) was to provide reliable data regarding human exposure and hazard posed by MNPs. However, in view of the numerous properties of MNP, it is impossible to test all variants and the mixture of associated chemicals. Hence, pragmatic approaches are needed as substitute for experimental testing, including strategies to deal with data gaps and the associated uncertainties, whilst considering the specific properties of MNPs. In this work, partners from the CUSP projects PlasticsFatE [...]