ISO/TS 20787:2017 specifies a test method, aiming to maximize repeatability and reliability of testing, to determine whether MNMs are toxic to aquatic organisms, specifically Artemia sp. nauplius. ISO/TS 20787:2017 is intended to be used by ecotoxicological laboratories that are capable in the hatching and culturing of Artemia sp. and the evaluation of toxicity of nanomaterials using Artemia sp. nauplius. This method uses Artemia sp. nauplii in a simulated environment, artificial seawater, to assess effects of nanomaterials. ISO/TS 20787:2017 is applicable to MNMs that consist of nano-objects such as nanoparticles, nanopowders, nanofibres, nanotubes, nanowires, as well as aggregates and agglomerates of such MNMs.