Carbon nanotubes
Toxicity of carbon nanotubes towards human and the environment

One difficulty encountered when studying the impact of carbon nanotubes is that they are considered to be a single type of nanoparticle, when in fact they are more a family of nanoparticles. The latter can vary not only in diameter and length, but also in wall number and microstructure. In most cases, CNTs are made up of one or more concentric cylinders, but there are also other structures called "bamboo" (CNTs are made up of a succession of compartments) or "fishbone" (herring-bones; in this case, CNTs can be seen as a stack of graphitic cones, with an open central channel). Other types of carbonaceous nanoparticles, such as nanohorns