Are nanomaterials more dangerous compared to micro- and larger particles?

Nanomaterials have unique properties, which make them so interesting for many novel applications. At the same time, concerns arose, whether these new properties lead to unexpected hazard towards humans and the environment. Many research activities were performed to tackle this question. So far, no unique mechanisms of hazard exclusively occurring for nanomaterials were discovered. The toxicity of a substance is rather determined by the type of material than by its size.