On a handful of toxicological endpoints triggered by ENMs, such as oxidative stress and inflammation, there is an abundance of published data. However, for the many other endpoints, information on the identification of which AOPs are relevant or specific to ENMs, and understanding the ENM-related molecular processes underlying the KEs is sparse or missing. This might be due to the lack of clear and centralized data and knowledge on the identification of ENMs, their characteristics and their interaction with biological systems. The management of these (toxicological) data needs to operate under FAIR (findability, accessibility, interoperability, and reusability) principles for effective RA and hazard assessment .