Nature Nanotechnology published findings from researchers in the United Kingdom showing that when mice were injected with long, thin stands of carbon nanotubes that share a similar shape with asbestos fibers, they suffered inflammation and lesions. The results prompted researchers to conclude that such exposure to carbon nanotubes potentially could lead to mesothelioma – a cancer of the lung lining that can take 30-40 years to appear following exposure.
“The results were clear,” said Professor Kenneth Donaldson from the University of Edinburgh, who lead the research team. “Long, thin carbon nanotubes showed the same effects as long, thin asbestos fibers.”
Donaldson stressed that researchers must still fill in some pieces of the puzzle. “We still don’t know whether carbon nanotubes will become airborne and be inhaled, or whether, if they do reach the lungs, they can work their way to the sensitive outer lining. But if they do get there in sufficient quantity, there is a chance that some people will develop cancer – perhaps decades after breathing the stuff,” he stated.
Donaldson added, however, that there is a silver lining to the research, as not all the carbon nanotubes behaved like asbestos. He stated that the short and curly carbon nanotubes did not appear to behave like asbestos. He also said that by finding out about the possible danglers of the long, thin carbon nanotubes, scientists can work to find ways to control the risks.
“It’s a good news story, not a bad one. It shows that carbon nanotubes and their products could be made to be safe,” Donaldson said, but added that the present study only tested for fiber-like behavior and does not exonerate carbon nanotubes from damaging the lungs in other ways.
The Question of Safety
Carbon nanotubes were discovered nearly 20 years ago and have been described as the wonder material of the 21st century. Light as plastic and stronger that steel, they are developed for use in new drugs, energy-efficient batteries and futuristic electronics.
But questions surround these nanoscale materials, including whether they cause harm or undermine a nascent market for all types of carbon nanotubes, including multi- and single-walled carbon nanotubes. Leading forecasting firms say sales of all nanotubes could reach $2 billion annually within the next four to seven years, according to an article in Chemical & Engineering News.
Andrew Maynard, chief science advisor to the Project on Emerging Nanotechnologies and a co-author on the paper, said that although scientists have been raising concerns about the safety of carbon nanotubes for over a decade, no existing research in the United States has addressed the issue.
“This study is exactly the kind of strategic, highly focused research needed to ensure the safe and responsible development of nanotechnology,” Maynard said. “It looks at a specific nanoscale material expected to have widespread commercial applications and asks specific questions about a specific health hazard.”
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.
Asbestos fibers are harmful because they are thin enough to penetrate deep into the lungs, but sufficiently long to confound the lungs’ built-in clearance mechanisms for getting rid of particles. Scientists fear that the carbon nanotubes with similar structures may have the same effect.
“This is a wakeup call for nanotechnology in general and carbon nanotubes in particular,” said Maynard. “As a society, we cannot afford not to exploit this incredible material, but neither can we afford to get it wrong – as we did with asbestos.”