- Full (HTML) - Full (PDF) - Supplemental Material - Related EHP Articles - PubMed:Related Articles - PubMed:Citation - Cited in PMC - Purchase This Issue

Aasgeir Helland,^1,2 Peter Wick,³ Andreas Koehler,¹ Kaspar Schmid,⁴ and Claudia Som¹

¹Technology and Society Lab, EMPA (Swiss Federal Laboratories for Materials Testing and Research), St. Gallen, Switzerland; ²Institute for Human-Environment Systems, ETH (Swiss Federal Institute of Technology) Zurich, Zurich, Switzerland; ³Laboratory for Biocompatible Materials, EMPA, St. Gallen, Switzerland; ⁴Institute for Occupational Health Sciences, Lausanne, Switzerland

Abstract
Carbon nanotubes (CNTs) are considered one of the most promising materials in nanotechnology, with attractive properties for many technologic applications. The different synthesis, purification, and postprocessing methods produce CNTs with different physical characteristics, which can be applied in different fields ranging from composite materials, medical applications, and electronics to energy storage. The widespread projected use of CNTs makes it important to understand their potential harmful effects. In this environmental health review we observed a remarkable range of results of some of the toxicology studies. The comparability should be improved by further standardization and introduction of reference materials. However, at present the findings of this review suggest several key points: a) there are different types of CNTs, and therefore they cannot be considered a uniform group of substances ; and b) in environmental compartments, CNTs can be bioavailable to organisms. The properties of CNTs suggest a possible accumulation along the food chain and high persistence. In organisms the absorption, distribution, metabolism, excretion, and toxicity of CNTs depend on the inherent physical and chemical characteristics such as CNT functionalization, coating, length, and agglomeration state that are influenced by the external environmental conditions during CNT production, use, and disposal stages. Characterized exposure scenarios could therefore be useful when conducting toxicologic studies. However, CNTs produce a toxic response upon reaching the lungs in sufficient quantity ; this reaction is produced in a time- and dose-dependent manner. The identification of possible risks to human health and environment is a prerequisite for a successful introduction of CNTs in future applications. Key words: carbon nanotubes, cytotoxicology, ecotoxicology, environment, environmental fate, human health, in vitro, in vivo, nanomaterials, nanotechnology, nanotoxicology. Environ Health Perspect 115:1125–1131 (2007) . doi:10.1289/ehp.9652 available via http://dx.doi.org/ [Online 10 May 2007]

Address correspondence to A. Helland, Technology and Society Lab, EMPA, Lerchenfeldstrasse 5, CH-9014 St. Gallen, Switzerland. Telephone: 41 712747848. Fax: 41 712747862. E-mail: asgeir.helland@empa.ch

Supplemental Material is available online (http://www.ehponline.org/docs/2007/9652/suppl.pdf) .

We thank A. Bruinink, V. Colvin, A. Maynard, H. Krug, and J. Wöörle-Knirsch for their comments on this paper.

We acknowledge the funding within the project "Nanorisk" from the Swiss Federal Office for the Environment (FOEN) , the Federal Office of Public Health (BAG) , the Federal Office for Professional Education and Technology (OPET-CTI) , and EMPA Materials Science and Technology.

The authors declare they have no competing financial interests.

Received 25 August 2006 ; accepted 10 May 2007.