From Chicago, at the EPA Emerging Pollutants Workshop
Carbon nanotubes could carry the same dangers to human lungs that asbestos does, says an Environmental Protection Agency researcher. Philip M. Cook of the EPA's Duluth, Minn., research laboratory and other scientists had previously linked the toxic potential of various needlelike fibers to their length, width, and shape. Fibers that damage lungs tend to fall into a size range comparable to some carbon nanotubes, an emerging family of synthetic fibers with a variety of potential industrial applications.
Cook and his colleagues have shown that short, thin mineral fibers are retained longer in the lungs than larger fibers are and that the short fibers can trigger cancer. Some commercially produced carbon nanotubes are 0.1 micrometer wide and 5 to 20 µm long, just about "the asbestos-fiber size that everyone believes is toxic," notes Cook.