There has been some concerns about carbon nanotubes could have asbestos-like properties [1] if not handled properly. Maybe that could be part of the reason? [

There has been some concerns about carbon nanotubes could have asbestos-like properties [1] if not handled properly. Maybe that could be part of the reason? [1] http://www.ucl.ac.uk/news/news-articles/0113/130115-chemistry-resolves-toxic-concerns-about-carbon-nanotubes http://www.ucl.ac.uk/news/news-articles/0113/130115-chemistr...