The BMBF project Nanostrukturierte Materialien Gruppierung hinsichtlich Arbeits-Verbraucher-und Umweltschutz und Risikominimierung (nanoGRAVUR) develops a list of criteria for a grouping of nanomaterials that share the same risk and hazard potential. Due to the large amount and the huge variety of engineered nanomaterials that have come to the market in numerous consumer products and to the complexity of the toxicity assays, it is impossible to determine their potential risk on a case-by-case basis. Therefore, there is an urgent need for a grouping of nanomaterials according to their potentials for exposure, hazard and risk. The BMTZ is involved in the development of criteria lists that help to identify quantifiable properties responsible for biological effects of nanomaterials. In addition, the BMTZ collects toxicity data to characterize nanomaterial classes that have not yet been analyzed and validates the grouping experimentally. During these toxicity assessments, factors influencing the outcome, such as contaminations with endotoxins or interferences of nanomaterials with assay components will be identified and characterized.