Methodology principles.
The properties of nanoparticles which can evolve according to experimental conditions, and the effects observed in laboratory on certain organisms could be different from real effects in a natural environment.
For a large majority, the ecotoxicity studies have been realized with a model specie (algae, bacteria,…) exposed to a nanomaterial in a single medium (water, ground or sediments) on short periods (not exceeding 3 weeks). It is thus possible to assess the toxicity and the toxic mechanisms of the effects of nanomaterials concerning a specie. But, this kind of studies doesn’t allow to evaluate the impacts of single or mixing nanomaterials and of their residue at the ecosystem level as a whole.