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Posted: September 13, 2007
Professor compares nanomaterials to asbestos - really?
(Nanowerk News) Cosmetics Design-Europe.com runs an article today saying that "Nanomaterials used in cosmetics have been compared to the invisible airborne killer, asbestos, by a high-profile chemistry professor at the BA Festival of Science in York."
Kristen Kulinowski, director of the International Council on Nanotechnology, and director of external affairs of the NSF Center for Biological and Environmental Nanotechnology, put her analysis of this article on her (unfortunately very infrequently updated) NanoRisk blog:
Taken out of context, i.e., without having heard the whole talk, it's difficult to say whether the scientist or the journalist got the story wrong. How does this story fail to meet the mark of good science/science reporting? Let me count the ways:
1. Equating carbon nanotubes and buckyballs.
"During a talk on nanotechnology and the environment, Tony Ryan, director of the Polymer Centre at the University of Sheffield, compared carbon nonotubes, otherwise known as buckyballs, to the construction material."
Leaving aside the possible Freudian slip in the misspelling of nanotube, carbon nanotubes are not buckyballs. They both belong to a class of materials known as fullerenes and can be referred to as "carbon-based nanomaterials" but they are not the same thing. The buckyball is the soccer-ball-shaped molecule and the nanotube is its longer, more slender cousin.
2. Assuming idealized form of carbon nanotube.
"One of the potential dangers with carbon nanotubes is: are we creating a new asbestos? The asbestos response is based on the shape of the particle. Part of the issue is in the shape of the molecule and how they're introduced," said Ryan.
We've all seen images of carbon nanotubes that look like rigid little sticks. I've also seen plenty of images of nanotube spaghetti where the tubes, which have a natural affinity for one another, all clump together into a tangled mess. Unlike asbestos. It's actually very difficult to individualize a sample of carbon nanotubes into single particles.
3. Assuming same route of exposure for nanotubes as asbestos, i.e., inhalation of individual particles.
"It is asbestos fibres rather than asbestos itself that causes serious health problems because they can become airborne and lodge themselves in the skin or lungs."
While it is true that liquid suspensions of carbon nanotubes injected in the lungs of rodents have been shown to pose hazards to lung tissue, there is little to no evidence that carbon nanotubes can be aerosolized into an inhalable form.
4. Equating carbon nanotubes and buckyballs. (see also #1)
"Although there has been no conclusive evidence to suggest that the size of carbon nanotubes poses serious health risks, Ryan advised caution with regards to cosmetic applications. The professor said: 'I wouldn't put buckyballs anywhere near my face.'"
I suspect this was the reporter's fault and that Professor Ryan probably said "nanomaterials" or "carbon nanoparticles" or some other more general term. This illustrates a very common issue that arises in discussions of nano EHS: the lumping together of all nanomaterials into a single class and then transferring documented effects from one type of particle onto another or even all nanomaterials.
5. Getting an organization's name wrong.
"Despite widespread anxiety about the use of nanomaterials there are 22 sunscreens and 77 cosmetic products, on the market that have been developed using nanotechnology, according to the Project on Emerging Technology."
A minor point, perhaps, but the inventory is maintained by the Project on Emerging Nanotechnologies.