New studies by scientists at the University of Edinburgh and Japan's National Institute of Health Sciences have raised disturbing new concerns that the physical structure of a particular type of carbon nanotube fiber, one that is already in use in the real world, may be as hazardous to your health as asbestos.
As the saying goes, if it looks like a duck and quacks like a duck, it’s reasonable to assume it’s a duck. In light of a new rodent study, environmental scientists worry that the same might apply to asbestos.
Certain long carbon nanotubes — tiny cylinders only 20 micrometers long and perhaps a few micrometers wide — have the same basic dimensions as toxic asbestos fibers. A broad body of data has suggested that the damage caused by asbestos traces more to its physical dimensions than its chemical recipe. So scientists had begun over the past few years expressing concerns that long nanotubes could trigger characteristic asbestos disease, especially mesothelioma — an unusual cancer that is nearly always fatal.
To date, the concerns that have been voiced about nanotechnology have been mostly speculative in nature, though worth careful and thorough consideration whether or not you abide by the precautionary principle, which of course our government and governments around the world largely do not, so these studies are something of a groundbreaking, and have caused nanoresearchers around the globe to pay more immediate attention to the potential health hazards of these materials, although more research is necessary since the method used in this study to induce the absorption of the carbon nanotubes by rats is not one that is realistic in the real world (where inhalation is our primary concern).
...long carbon nanotubes prompted immediate inflammation and a rapid development of lesions in treated mice. Those lesions, symptomatic of the body’s attempt to wall off persistent, irritating materials, are an early — if nonspecific — symptom of asbestos toxicity. Administering long asbestos fibers to mice caused these same responses. Injecting short asbestos fibers or short or tangled carbon nanotubes did not trigger these effects.
...[T]his study "is a long way" from showing that carbon nanotubes can cause diseases characteristic of asbestos, such as mesothelioma, says André E. Nel, director of the division of nanomedicine at the University of California, Los Angeles. Still, he adds, it demonstrates that carbon nanotubes "do have pathogenic potential." What’s more, the idea that they might be inhaled "needs to be entertained," he says, and where these long carbon nanotubes are used, "proper precautions" should be taken to ensure inhalation will be minimized.
Obviously, these studies are just the beginning of a long round of follow-up studies that will be exploring this issue, and are not the basis for drawing immediate and dire conclusions, but it is a cause for alarm as well as for reconsideration of the proper balance of precaution and innovation as we head into the great technological unknown [another diary, another time]. Along those lines, it's also important to note the distinction in the findings that only one type of nanotube [rigid multiwalled carbon nanotubes (MWNTs)] exceeding a particular length was found to cause these inflammatory effects - other types of nanotubes were apparently easily absorbed by body macrophages.
One thing is for certain - we do not want to release another asbestos into our environment.
Occupational exposure to asbestos through mining and industrial operations has led to a pandemic of lung diseases. Workers who inhale asbestos fibers develop inflammation and scarring in the mesothelial lining of the lungs, which can lead to mesothelioma.
Because certain types of carbon nanotubes are structurally similar to asbestos, scientists have speculated that nanotubes might also have asbestos' devastating health effects. "For a fiber to be harmful, it has to be thin, long, and insoluble in the lung," says Ken Donaldson of Scotland's University of Edinburgh Centre for Inflammation Research, who spearheaded one of the studies.
Without a doubt, we need to keep up on these kinds of issues, but it's very hard as citizens to do so, especially as we delve deeper into the more arcane technological applications of 21st century modern science.
Some final words:
Kristen M. Kulinowski, executive director for policy at Rice University's Center for Biological & Environmental Nanotechnology, cautions that researchers do not yet know whether carbon nanotubes can be inhaled in sufficient quantities to exhibit the biological response seen in these studies. Even so, she warns that action should be taken to protect workers and consumers.
"As a society, we cannot afford not to exploit this incredible material," says Andrew Maynard, a member of Donaldson's team and chief science adviser of the Project on Emerging Nanotechnologies, "but neither can we afford to get it wrong—as we did with asbestos."
I imagine that Mr. Maynard is engaging in a bit of hyperbole there, but perhaps there is some real reason for his being a true believer in this relatively new techology, I'm certainly not an expert so wouldn't be informed enough to say either way, but do find it somewhat hard to believe we can't afford to live without rigid multiwalled carbon nanotubes (already), but maybe I'm just being rigid and dense.
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For background on carbon nanotubes, you can check these three links for a primer:
Carbon Nanotube [Wiki]
Potential Applications [Wiki]
Buckytube Applications
In nanotechnology or the building of extremely small machines and computers, a nanotube is a long, cylindrical carbon structure consisting of hexagonal graphite molecules attached at the edges. The nanotube developed from the so-called Fullerene, a structure similar to the way geodesic domes, originally conceived by R. Buckminster Fuller, are built. Because of this, nanotubes are sometimes called buckytubes .
Some nanotubes have a single cylinder; others have two or more concentric cylinders. Nanotubes have several characteristics: wall thickness, number of concentric cylinders, cylinder radius, and cylinder length. Some nanotubes have a property called chirality, an expression of longitudinal twisting.
Researchers have suggested several applications for nanotubes. The structures might be assembled into microscopic mechanical systems called nanomachines. Because graphite can behave as a semiconductor, nanotubes might be used to build microscopic resistors, capacitors, inductors, diodes, or transistors. Concentric nanotubes might store electric charges because of capacitance among the layers, facilitating the construction of high-density memory chips.