“As materials reach the nanoscale, they often no longer display the same reactivity as the bulk compound. New approaches for testing and new ways of thinking about current materials are necessary to provide safe workplaces, products, and environments as the manufacturing of nanomaterials and products increases and, as a result, exposure to nanomaterials increases. The diverse routes of exposure, including inhalation, dermal uptake, ingestion, and injection, can present unique toxicological outcomes that vary with the physicochemical properties of the nanoparticles in question.”1
“Exposure to fine particulate dusts is known to lead to pulmonary diseases. The idea that any poorly soluble particles administered in sufficient quantities to the lung can cause an inflammatory reaction has arisen following the demonstration of rat lung overload . . . . An important challenge in particle toxicology is to define the quantity that produces inflammation i.e. define the effective dose. Since the late 1980’s, toxicological evidence has been emerging indicating that the health effects associated with inhaling ultrafine particles may not be closely associated with particle mass. Early studies with PTFE (polytetrafluoroethylene) particles around 20 nm in diameter showed that airborne concentrations of a supposedly inert insoluble material lower than 50?g m-3 could be fatal to rats . . . . Since then, many studies have indicated that the toxicity of insoluble materials increases with decreasing particle size, on a mass for mass basis . . . . .”2
1. G. Oberdörster, A. Maynard, K. Donaldson, et al, “Principles for characterizing the potential human health effects from exposure to nanomaterials: elements of a screening strategy,” Particle and Fibre Toxicology 2005, 2:8, § 3.0.
2. R. Aitken, K.Creely, C. Tran, ”Nanoparticles: An occupational hygiene review,” Prepared by the Institute of Occupational Medicine for the Health and Safety Executive 2004, Research Report 274, at 12 (2004).