The Los Angeles Times (5/21, Zarembo) reports that "[c]ertain types of carbon nanotubes — microscopic graphite cylinders used in a small, but growing, number of Space Age applications — could pose a cancer risk similar to that of asbestos if inhaled," according to a study published online May 20 in the journal Nature Nanotechnology. Nanotubes, which "were discovered in the early 1990s,…have been billed as wonder particles for their incredible strength, low weight, and ability to conduct heat and electricity." Nevertheless, some experts have long "suspected that certain types of nanotubes could pose the same danger as asbestos fibers."
For the study, lead author Dr. Ken Donaldson, of the MRC/University of Edinburgh Centre for Inflammation Research, and colleagues, "tracked the short-term effects of various kinds of carbon nanotubes and asbestos fibers injected into the…abdomens" of mice, "near the mesothelium," according to the Washington Post (5/21, A2, Weiss). The "tissue surrounding the lungs and other organs" is typically "where certain kinds of asbestos fibers tend to migrate after being inhaled."
The researchers "injected four groups of mice: one with short nanotubes about five microns in length, one with long nanotubes about 20 microns in length, one with asbestos, and one with small carbon clumps," the New York Times (5/21, A22, Chang) adds. The authors found that rodents "injected with the short nanotubes or small carbon clumps did not develop disease." But, "[t]hose injected with long nanotubes or asbestos developed lesions on the tissue lining." Dr. Donaldson stated that "given more time, the lesions caused by the long nanotubes would have developed into mesothelioma."
Still, "the researchers said the link between long, straight, multi-walled carbon nanotubes and cancers was not proven," the BBC (5/20) explained. In fact, Dr. Donaldson noted, "We are a long way from saying that any form of carbon nanotubes causes mesothelioma."
The AFP (5/21) points out that "this is the first study to show that…carbon nanotubes can have the same damaging impact on the mesothelium" as asbestos. Study co-author Andrew Maynard said that the world is "at the very, very beginning of using these materials commercially." Therefore, "[g]reat caution must be exercised before introducing such products into the market if long-term harm is to be avoided," he added.
Due to the uncertainty posed by nanotubes, "the researchers hope to pressure companies developing carbon nanotube-based materials to reveal whether they are using longer strands such as the ones that appear to act like asbestos — which was once a wonder material, too, before its cancerous consequences were discovered," the AP (5/21, Bergstein) reports. The San Francisco Chronicle (5/21, Fernholm) also covers the story.
