*4.1. In Vivo Techniques*

In vitro assessments have augmented significantly, however in vivo confirmation is still needed for understanding as well as interpreting results. Additionally, animal testing was also associated with the NanoTEST venture, whose objective was to recognize the effects on the physiology of verified living organisms. Presently, the Organization for Economic Co-operation and Development (OECD) offers certain examination strategies on which biomarkers must be utilized for every testing organism (Juillerat-Jeanneret et al., 2015, [200]).

Generally, there are several studies on human toxicity by means of rodent models, while only limited research exists in vivo dealing with available nanomaterial ecotoxicity. Additionally, a majority of those observed in the studies reflect the influence of nanomaterials on aqueous organisms, due to the fact that marine and continental waters are the chief reception compartments. As a general rule, rodents (Wistar rat and mice), fish (example, Danio rerio), mollusks (example, *Lymnaea stagnalis*), microcrustaceans (example, *Ceriodaphnia dubia, D. pulex, Daphnia magna*), nematodes (example, *Caenorhabditis elegans*), algae (example, *Raphidocelis subcapitata*), and bacteria (example, *Aliivibrio fischeri*) are mostly utilized testing organisms for the assessment of acute toxicity.
