Assessment of potential MIE activation showed that the majority of ENMs from the selected papers were described to cause either ROS production (33%), activation of Nrf2 (27%), and DNA damage (24%), as presented in Figure . The AOP-Wiki describes 238 MIEs in total (48), of which 11 could be linked to the ENMs described in the literature, though 3 of these were induced by the same 23 ENMs (namely "ROS generation from photoactivated chemicals", "Chronic reactive oxygen species" and "Increase, Reactive oxygen species production") which were therefore only shown once in Figure . In the papers, 43 molecular effects of the ENMs were mentioned, 31 of which could be linked to 64 KEs in AOP-Wiki of which 11 are MIEs (see Table ). During the literature review phase, sixteen different physicochemical properties were extracted, if reported in the paper. These properties were collected in a spreadsheet (Additional file 2), and the most documented properties were converted to RDF, including the primary size, hydrodynamic diameter, shape, diameter, specific surface area, bundle diameter and zeta potential. Table (Additional file 1) shows the methods used to obtain each physicochemical property. In addition to the original data, normalized data were derived from the original data and added to the RDF.