Respiratory system

When considering the risks associated with nanomaterials, exposure is the key factor in defining risk with hazard being a key variable. With regards to the route of exposure, the lungs cause the greatest concern due to the sensitivity and ability to accumulate an internal dose. While the body is well adapted to constant exposure to particles from a variety of sources, with effective clearance and immunological defense mechanisms in place, exposure can also lead to disease and a real concern is the effect that new nanomaterials may have. In the present chapter, we describe the routes of exposure into the body via the lung and factors affecting this, as well as possible pathological reactions to nanomaterials ranging from inflammation and fibrosis to carcinogenicity. It is important to note that nanoparticles, like other particles, show differences and heterogeneity in their pathogenicity and a key area of research is the identification of physicochemical attributes, such as shape, size, etc. that contribute to or dictate toxicity.