Biological effects of nanoparticulate materials

A range of morphologically nanoparticulate materials including Ag, NiO, TiO₂, multiwall carbon nanotubes, and chrysotile asbestos have been characterized by transmission electron microscopy. All but the TiO₂ (anatase and rutile) were observed to exhibit some cytotoxicity at concentrations of 5 μg/ml for a murine macrophage cell line as a respiratory response model. Silver exhibits interesting systemic differences for animal and human toxicity, especially in light of its nanoparticulate materials, and should be avoided even if there is no detectable in vitro cytotoxic response, as a prudent approach to their technological applications.