Are nanoparticles safe?
As we commonly think of the term “safe”, some nanoparticles are undoubtedly safe. In each breath we take in a city we breathe in more than 1000000 nanoparticles without any apparent ill-effect. However, safety is not an absolute concept. It depends on the material itself (not all nanoparticles have the same absolute toxicity) and the levels at which people or the environment are exposed.
