The next asbestos: Carbon nanotubes linked with mesothelioma in rodent study
Posted May 20, 2008
Multi-walled carbon nanotubes cause asbestos-like damage in test mice. That is what a new study is just out today in Nature Nanotechology is reporting, titled: Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study. The International Council on Nanotechnology (ICON), Rice University has posted an excellent scientific review of this and an earlier study with similar results.
NRDC summarized the findings of five different research groups that since 2004 have reported that single-walled carbon nanotubes (SWCNTs) cause lung damage in test rodents, including dose-dependent rapid lung inflammation, rapid progressive fibrosis, and granulomas.
Carbon nanotubes are atom-thick sheets of graphite formed into cylinders. They may be formed from a single layer of graphite or they may consist of multiple concentric layers of graphite, resulting in multi-walled carbon nanotubes. They are estimated to be 100-times stronger and six-times lighter than steel, making them useful to strenthen building materials. Already they are found in many consumer products including super-strong tennis rackets, hockey sticks, racing bike frames, car parts, and golf clubs.
The ropelike filaments of carbon nanotubes are long, thin, and insoluble; these qualities are associated with the cancer-causing effects of asbestos and other deadly fibers.
In the trade press (Nanowerk), Donaldson is quoted as saying that, " "The results were clear ...Long, thin carbon nanotubes showed the same effects as long, thin asbestos fibers."
The website of the Woodrow Wilson Center Project on Emerging Nanotechnologies notes that "widespread exposure to asbestos has been described as the worst occupational health disaster in U.S. history and the cost of asbestos-related disease is expected to exceed $200 billion, according to major U.S. think tank RAND Corporation."
But, dollars don't tell the human toll. NRDC reports that in the United States, we still have more than one death per hour—approximately 10,000 per year—as a legacy from past and continuing exposure to asbestos. The global death rate is estimated to be 10 times higher.
Today's study authors report their results thus: "Here we show that exposing the mesothelial lining of the body cavity of mice, as a surrogate for the mesothelial lining of the chest cavity, to long multiwalled carbon nanotubes results in asbestos-like, length-dependent, pathogenic behaviour. This includes inflammation and the formation of lesions known as granulomas. This is of considerable importance, because research and business communities continue to invest heavily in carbon nanotubes for a wide range of products under the assumption that they are no more hazardous than graphite. Our results suggest the need for further research and great caution before introducing such products into the market if long-term harm is to be avoided."
Recklessly exposing workers and the general population to deadly chemicals is neither humane nor civilized. Our society can do better this time around. Regulators must step in and prevent nanomaterials from being used in ways that may result in human exposure or environmental releases until they are safety tested and regulated.
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