Since additional issues, however, must be considered to find out, for example, whether the particular properties of the nanovariant of a material may influence or change the material’s behavior in biological systems on a physical, chemical or on any other level, the nanomaterials are analyzed toxicologically. There are two basically different methods, i.e. in vitro or in vivo, that toxicologists, mostly chemists, medical scientists or biologists, may choose for conducting such studies.
In addition to assessing the possible biological effects of nanomaterials inside the human body, it is important to evaluate the materials’ epidemiological impacts, i.e. their effects on the health of the overall population. Workplace hazards, for example, are among the risks that need to be studied.

Additionally, the influence of engineered nanoparticles on all organisms in our environment has to be considered and studied. Does an environmental “pollution” with nanoparticles exert similar effects compared to chemicals?
For all that, it is important to point out that the health hazards of any chemical substance almost always depend on the concentration. According to Paracelsus (1493-1541), “all things are poison; there is nothing without poison; only the dose makes a thing non-poisonous”. It has remained valid until the present day that any substance has a biological/toxicological effect. Only the concentration (or dose) that is taken up by the organism decides whether that effect is negative or not.