Larry Greenemeier, Scientific American, May 20, 2008
EXCERPTS FROM THE ARTICLE:
Inhaling carbon nanotubes could be as harmful as breathing in asbestos, and its use should be regulated lest it lead to the same cancer and breathing problems that prompted a ban on the use of asbestos as insulation in buildings, according a new study posted online today by Nature Nanotechnology.
During the study, led by the Queen's Medical Research Institute at the University of Edinburgh/MRC Center for Inflammation Research (CIR) in Scotland, scientists observed that long, thin carbon nanotubes look and behave like asbestos fibers, which have been shown to cause mesothelioma , a deadly cancer of the membrane lining the body's internal organs (in particular the lungs) that can take 30 to 40 years to appear following exposure. Asbestos fibers are especially harmful, because they are small enough to penetrate deep into the lungs yet too long for the body's immune system to destroy.
The researchers reached their conclusions after they exposed lab mice to needle-thin nanotubes: The inside lining of the animals' body cavities became inflamed and formed lesions.
Carbon nanotubes are generally made from sheets of graphite no thicker than an atom—about a nanometer, or one billionth of a meter wide—and formed into cylinders, with the diameter varying from a few nanometers up to tens of nanometers. (They can be hundreds or even thousands of nanometers long.) There is a greater concern about "multiwalled" nanotubes consisting of several reinforced cylinders, because they are able to retain their pointy shapes better than thinner nanotubes.
"There is an immediate need to examine how carbon nanotubes are being used and see if there's any chance that [people] are being exposed to dangerous materials," Maynard says, adding that no one paid attention to the dangers of asbestos until it was too late for a lot of people.