One of the NanoDiode activities was to elaborate further on processes of ‘regulatory research for effective risk assessment’, bringing together researchers and industrial partners with risk assessors to discuss sensible ways forward for developing precautionary risk measures for using nanomaterials. Three workshops were organised to discuss these items in a structured debate amongst the identified stakeholders. As a starting point and to structure these debates two starting documents were developed. The first document summarizes current issues in risk assessment of nanomaterials that interfere in the current risk assessment methodologies and need a thorough reflection to make these fit for nano. For some of these issues, in this note we call them ‘dilemmas’, fundamental adaptations should have to be made in the current methodologies. The second document develops a framework for uncertainties visualizing the interactions between relevant stakeholders. These documents were used as a background for the workshops (Ch. 2 and Ch. 3). A report of the workshops is given in Ch. 4, while Ch. 5 summarizes the main outcomes.