The potential risks of nanomaterials: a review carried out for ECETOC
Paul J.A. Borm, David Robbins, Stephan Haubold, Thomas Kuhlbusch, Heinz Fissan, Ken Donaldson, Roel P.F. Schins, Vicki Stone, Wolfgang Kreyling, Juergen Lademann, Jean Krutmann, David Warheit, Eva Oberdorster
Particle and Fibre Toxicology 2006, 3:11 (14 August 2006)
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http://www.particleandfibretoxicology.com/
Recent years have witnessed unprecedented activities in the area of Nanoscience and Nanotechnology and drive the production of new advanced manufactured nanomaterials. Manufactured Nanoparticles, mostly understood as particles with at least one dimension less then a 100 nm, are an important type and constituent in many of these materials. The use of manufactured Nanoparticles in industrial and downstream user applications is diverse. On the one hand they are immobilized in matrix applications like adhesives, emulsions, polymer matrices where they either interact with the matrix or aggregate to form larger particles. On the other hand, for other applications such as optics or electronics single, dispersed particles are required. There is a common understanding amongst regulatory and industrial stakeholders that together with the beneficial effects of new materials potential adverse effects need to be evaluated at an early stage. Therefore the aim of this report is to summarize and review the available data on Nanoparticles with regard to occupational and consumer exposure, toxicology and environmental effects. This White Paper represents a multidisciplinary expert report, with the objective of weighing the evidence and provides a preliminary risk estimate for manufactured Nanoparticles. During the last few years, research on toxicologically relevant properties of Nanoparticles has increased. A number of international research projects and additional activities are ongoing in the EU and the US, nourishing the expectation that more relevant technical and toxicological data will be published. Their widespread use allows for potential exposure to manufactured Nanoparticles during the whole lifecycle of a variety of products. When looking at possible exposure routes for manufactured Nanoparticles, inhalation, dermal and oral exposure are the most obvious, depending on the type of product in which Nanoparticles are used. This review has shown that: 1. Nanoparticles can deposit in the respiratory tract after inhalation. For a number of Nanoparticles, oxidative stress-related inflammatory reactions have been observed. Tumour-related effects have only been observed in rats, and might be related to overload conditions. There are reports that specific Nanoparticles can enter the brain via the olfactory epithelium. Conflicting studies report particle translocation into the systemic circulation after inhalation of specific Nanoparticles. These findings urge the need for additional studies to further elucidate these findings and to characterize the physiological impact. 2. There is little evidence from skin penetration studies that dermal applications of metal oxide nanoparticles used in sunscreens lead to systemic exposure. The question has been raised whether the usual testing with healthy, intact skin will be sufficient. 3. Uptake of Nanoparticles in the gastrointestinal tract after oral uptake is a known phenomenon, of which use is intentionally made in the design of food and pharmacological components. 4. This review indicates that only few specific Nanoparticles have been investigated in a limited number of test systems and extrapolation of this data to other materials is not possible. Air pollution studies have generated indirect evidence for the role of combustion derived Nanoparticles in driving adverse health effects in susceptible groups. Experimental studies with some bulk Nanoparticles that have been used for decades suggest various adverse effects. However, nanomaterials with new chemical and physical properties are being produced constantly and the toxicity of these is unknown. Therefore, despite the existing database on Nanoparticles, no blanket statements about human toxicity can be given at this time. In addition, limited ecotoxicological data for nanomaterials precludes a systematic assessment of the impact of Nanoparticles on ecosystems.
