University of Rochester, USA
Posters-Accepted Abstracts: J Drug Metab Toxicol
The rapid introduction of nanotechnology in manufactured goods for diverse industrial applications and consumer uses promises great benefits, which â�?�? however â�?�? may be significantly offset because of toxicity implications. Indeed, serious concerns have been expressed about risks posed by exposure to engineered nanomaterials (ENMs), their potential to cause undesirable health effects, contaminate the environment and thereby adversely affect living systems.For example, carbon and TiO2 nanoparticles inhaled by rats at extraordinarily high concentrations in chronic studies induced lung tumors due to lung overloading, although carbon black and TiO2 nanoparticles are generally considered to be rather benign materials. As another example, carbon nanotubes administered acutely to rats and mice as bolus or by inhalation of high concentrations induced significant pulmonary inflammation and intraperitoneal and intrapleural injections of multi-walled carbon nanotubes (MWCNT) caused pleural granulomata and cancer of the pleural lining.These findings caused great concern about asbestos-like long-term toxicity and carcinogenicity of fiber-shaped nanomaterials. Although subsequent three-month subchronic rat inhalation studies with MWCNT did not result in carcinogenicity, the short exposure duration of these studies is insufficient for identifying a carcinogenic risk. New data on translocation and clearance mechanisms of inhaled MWCNT to pleural tissue and other target sites have to be considered. An example of assessing nanomaterial safety based on subchronic inhalation studies in rodents with multi-walled carbon nanotubes and based on a comparison to positive and negative benchmark materials will be discussed, emphasizing the importance of using well-designed studies to identify and separate real from perceived risks.