The prognosis for the development of nanotoxicology is often qualitative. For example, the goal of system nanotoxicology is to endeavor reproducibility and relevance to experimental nanosafety research and discovering nano-specific toxicity biomarkers and pathways. The toxicologists also Figure . Main keywords in 2020 and their co-occurrence. The "green" cluster is associated with environmental pollutants (e.g., cadmium) and ecotoxicology. The "purple" cluster is associated with heavy metals and oxidative stress. The "brown" cluster is associated with noble metals and medical application. The "blue" cluster is associated with targeted delivery and cancer treatment. The "pink" cluster is associated with nanoparticles functionalization strategies. The "light blue" cluster is associated with biodistributions, nanotoxicity, and nanomedicine.