One of the things I’ve noticed about the nanomaterials safety debate is how quickly it devolves to: nanomaterials are good (some media reporters, business and corporate lawyers) vs nanomaterials are bad (some media reporters and civil society groups). Unfortunately, we still don’t know much about nanomaterials and their possible effects on health and the environment but there is enough evidence to support a single position if you’re willing discount evidence that doesn’t support your case. There are even people (pro and con) who will use evidence that doesn’t support their case very well unless they leave out details.
Take for example, this interview with Pat Roy Mooney (executive director of the ETC Group) at the Elevate Festival, October 2009 in Austria. Much of what he has to say is quite right (more work needs to be done to ensure safety) but you might get the impression that all this nanotechnology research that’s been talked about has resulted only in consumer products such as sunscreens and cosmetics. At about 4 mins., 15 secs., the reporter challenges Mooney and points out that the research may be very helpful in cleaning water (vital in some areas of the world) and could have other benefits. Mooney concedes the point, grudgingly.
Oddly, Mooney spends quite a bit of time suggesting that gold nanoparticles are a problem. That may be but the more concerning issue is with silver nanoparticles which are used extensively in clothing and which wash off easily. This means silver nanoparticles are ending up in the water supply and in our fish populations. Studies with zebrafish strongly suggest far more problems with silver nanoparticles than gold nanoparticles. You can check this paper (which compares the two nanoparticles), this paper (about silver only) and this paper (about silver only) or run a search.
Mooney goes on to describe problems with other nanomaterials that I’m unfamiliar with, but I don’t know how far I can trust the information he’s giving me.
Mooney isn’t the only one who likes to remove nuance and shading. In a recent interview on the Metropolitan Corporate Counsel website, one of the interview subjects, William S. Rogers, Jr., essentially dismisses concerns about carbon nanotubes with this:
Rogers: Before the EPA announcement in January, 2010 concerning the proposed SNUR, a series of studies was done beginning in the United Kingdom with a study led by Poland, et al. (2008). That study involved the injection of multi-walled nanotubes into the abdomen of mice, the mucosal lining of which is identical to the mesothelium of the pleura or chest. The injection directly into the abdomen was intended to simulate exposure of the mesothelium in the chest due to inhalation exposure. Approximately 90 days later they examined the biological changes who had taken place as a result of exposure of the abdominal mesolthelial lining to the carbon nanotubes. They reportedly found evidence of inflammation that was consistent with the type of inflammation that had traditionally been recognized in people who had inhalation exposure to asbestos fibers and who later developed mesothelioma. They did not find actual mesothelioma in the mice, but rather what were thought to be precursors to such cancers. The result of publication of these findings was an alarmist reaction that carbon nanotubes posed a danger to humans analogous to that of asbestos fibers. This became headline news.
Up to this point I could agree with him, but now Rogers goes on to point out the study’s shortcomings,
The problem with the study was that the mice were exposed to massive doses of nanotubes by injection, which is not a natural or likely cause of human exposure. The test methodologies were a poor analog for what likely human exposure would be in any setting. Many commentators criticized the study’s findings and suggested that its conclusions about a potential relationship between carbon nanotubes and asbestos fibers was flawed because it rested largely on their shape similarity (long and thin); however, for the last two years there has been talk in the popular media about whether the risks associated with all nanomaterials are akin to those associated with asbestos fibers. The only similarities between carbon nanotubes and asbestos fibers is their long aspect ratio, unlike other nanomaterials. There has been more focus on carbon nanotube toxicity than on other nanomaterial substances, which has percolated up to the EPA. EPA has now decided to treat carbon nanotubes separately from other nano-objects.
Rogers fails to mention that this was a pilot study which was intended to lay the basis for further research. Dr. Andrew Maynard, one of the authors of the study, noted in a March 26, 2009 posting on his blog (2020 Science) further work had been done,
I’m looking at an electron microscope image of a carbon nanotube – as I cannot show it here, you’ll have to imagine it. It shows a long, straight, multi-walled carbon nanotube, around 100 nanometers wide and 10 micrometers long. There is nothing particularly unusual about this. What is unusual is that the image also shows a section of the lining of a mouse’s lung. And the nanotube is sticking right through the lining, like a needle through a swatch of felt.
The image was shown at the annual Society of Toxicology meeting in Baltimore last week, and comes from a new study by researchers at the National Institute for Occupational Safety and Health (NIOSH) on the impact of inhaled multi-walled carbon nanotubes on mice. [You can find out more about the NIOSH study here]
It’s highly significant because it takes scientists a step closer to understanding whether carbon nanotubes that look like harmful asbestos fibers, could cause asbestos-like disease…
Both the carbon nanotube studies mentioned here are studies of long, multi-walled carbon nanotubes. This distinction is important as substances at the nanoscale can behave differently from each other depending on their shape and size. Both Maynard and the NIOSH researchers suggest that more study is required but clearly the evidence is mounting.
Interestingly, the Good Nano Guide (GNG)* page on carbon nanotubes mentions the Poland study but not the NIOSH Study. The page also notes that at least one study indicates issues with single-walled and multi-walled carbon nanotubes as well as C60 (fullerenes). I wonder if there’s a policy about including only studies that have been published in peer-reviewed journals.
(*a ‘best practices for nanomaterials’ wiki hosted by the International Council on Nanotechnology ETA (April 12, 2010: From Dr. Kristen Kulinowski, “As to your question about our policy for posting information at the GNG, there is no policy that states we only publish peer-reviewed papers.” Dr. KK has offered this and more information about the GNG in the comments.)
The media also are playing a role in this discussion. I’ve noted before Andrew Schneider’s nanotechnology series for AOL News, from his article Obsession with Nanotech Growth Stymies Regulators,
Separately, the NIOSH team discovered that beyond the well-documented lung damage that comes from inhalation of carbon nanotubes, [emphasis mine] those heavily used carbon structures were causing inflammation of the brain in the test animals.
Except for the fact that “well-documented lung damage that comes from inhalation” is an over statement, Schneider’s article is a good read although as I’ve noted elsewhere I don’t know how far to trust his information. [ETA: April 21, 20010, Schneider also fails to note the the type of carbon nanotube (likely the long, multi-walled ones) on which he bases his unsubstantiated claim. ]
After writing all this, I’m torn. On the one hand, I do think that if people like Schneider and Mooney had their way, none of us would be eating potatoes, tomatoes, or eggplants. After all, they’re members of the nightshade family and the ill effects of ingesting other members of that family, belladonna (deadly nightshade) and datura (jimson weed), are well documented. On the other hand, folks like William Rogers are all too willing dismiss some very troubling research as their clients strive to bring products to market, seemingly regardless of any consequences.
ETA: Happy Weekend!