Research on health effect of breathing nanoparticles
The National Institute for Occupational Safety and Health (NIOSH) is researching the health effects that nanoparticles may have on workers who handle them and who are exposed to them. NIOSH recently published research that measured for the first time the health effects of inhaling a common nanoparticle, the single-walled carbon nanotube. In this study, researchers examined what happens when mice breathe in carbon nanotubes.
A nanoparticle of a certain material can behave much differently than a larger, more familiar-sized particle of the same material. Early research shows that materials that enter the body as nano-sized particles may have harmful health effects, even for some materials previously considered safe at larger sizes.
Source : http://osha.europa.eu/en/news/niosh-research-on-health-effect-of-breathing-nanoparticles