Phosphorus (P) is a key nutrient with crucial importance for agriculture and global food security. Phosphate rock is an intensively exploited finite resource, concentrated only in a few countries worldwide, leading to strong import dependency and insecurity for countries with resource deficits. Thus, in 2014 the EU Commission declared P rock as one of the 20 critical resources for the EU. Recently, significant efforts and priority funding were focused on developing materials and technologies for P recovery from secondary P rich sources, such as wastewater, following the EU Circular Economy paradigm. Engineered nanostructured materials, predominantly metal oxides/hydroxides, have been frequently reported as excellent sorbents for P in wastewater. However, the uncertainty regarding possible ecotoxicological hazards arising from the use of these custom materials has produced new research gaps. The main purpose of this Marie Curie action is to assess the environmental risk and potential toxicity of a novel, highly efficient nanostructured P sorbent material and optimize its structure to exclude any ecotoxicological risks from its application. Following the interdisciplinary approach bridging Nano-Toxicology, Materials Science and Environmental Engineering, “NanoPhosTox” will explore various test systems to evaluate the biological effects of the proposed material. Attention will be focused mostly on ecotoxicity tests based on OECD and ISO test protocols, such as Vibrio fischeri, Algae and Daphnia assays, which allow assessing toxicity effects of the material’s precursors, including nanoparticles. Thus, “NanoPhosTox” will build on the previous successful research which established the fundamentals of an innovative, robust and highly competitive technology for the simultaneous removal and recovery of P from wastewater. The ultimate goal of this action is to advance the further commercialization of the technology by verifying its environmentally friendly application.