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In vivo comet assay of multi-walled carbon nanotubes using lung cells of rats intratracheally instilled


Correspondence to: Makoto Ema, Research Institute of Science for Safety and Sustainability, National Institute of Advanced Industrial Science and Technology (AIST), 16–1 Onogawa, Tsukuba, Ibaraki 305–8569, Japan. E-mail:


The genotoxicity of multi-walled carbon nanotubes (MWCNTs) was evaluated in vivo with comet assays using the lung cells of rats given MWCNTs. The MWCNTs were intratracheally instilled as a single dose at 0.2 or 1.0 mg kg–1 or a repeated dose at 0.04 or 0.2 mg kg–1, once a week for 5 weeks, to male rats. The rats were sacrificed 3 or 24 h after the single instillation and were sacrificed 3 h after the last instillation in the repeated instillation groups. Histopathological examinations of the lungs revealed that MWCNTs caused inflammatory changes including the infiltration of macrophages and neutrophils after a single instillation and repeated instillation at both doses. In comet assays using rat lung cells, no changes in % Tail DNA were found in any group given MWCNTs. These findings indicate that MWCNTs do not have the potential to cause DNA damage in comet assays using the lung cells of rats given MWCNTs at doses causing inflammatory responses. Copyright © 2012 John Wiley & Sons, Ltd.