Precision and accuracy key when discussing nano
07/01/2007
The American Association of Cancer Research’s recent article, “Nanoparticles Can Damage DNA, Increase Cancer Risk,” provides a good example of how researchers can unintentionally damage the public’s ability to develop a balanced understanding of nanotechnology.
The article covers research done at the University of Massachusetts and relays an interview with an undergraduate researcher, Sara Pacheco, who conducted a study on genotoxicity of two nanoparticle types. According to the article, Ms. Pacheco attributes a number of unfavorable qualities to “nanoparticles” and claims “such nanoparticles” are being used in a series of consumer goods.
Unhelpful and misleading
The article intimates that nanoparticles are a monolithic entity. As I am sure Ms. Pacheco is aware, there are vastly different nanoparticle forms, ranging from nano-metals to carbon nanotubes, buckyballs, nano-metal oxides, nano-clays, quantum dots, and several others. Even within a class such as carbon nanotubes, the number of walls, chirality, length, diameter, and surface chemistry all profoundly affect reactive properties.
Talking about “nanoparticles” is, in fact, a bit like talking about “materials”-and the statement “materials can damage DNA” is about as accurate and as informative as the article’s headline. Aside from the article’s assertion that nanoparticles are all approximately 100 nanometers in size (and certainly that is subject to debate), little can be said about them as a group. The article even admits this, stating that “very little is known about how [nanoparticles] behave,” a fact that surprisingly does not stop the author from making definitive statements about them.
As Ms. Pacheco is quoted as saying, studies like the one she and her colleagues conducted are valuable in that they improve our understanding of how a particular nanomaterial interacts with human biology. It is a mistake however, to use these findings to imply a threat from products that contain that nanomaterial. Just as there is a difference in toxic effect between drinking and inhaling water, there is a difference between holding a tennis racket with some nanotubes in the handle and directly introducing nanotubes to the DNA of cancer cells. The study neither uses the same formulations of carbon nanotubes found in consumer products, nor does it use an exposure route that represents how a consumer would come in contact with nanotubes through using the products.
In fact, in many cases where carbon nanotubes are incorporated into a matrix (like a plastic or ceramic), they bind very tightly to their surrounding and there is no evidence that they are released through use. Furthermore, most carbon nanotubes have a very high tendency to clump so that even if there existed a case where they were released, they would likely lump themselves into macro-scale carbon before contacting a cell.
Fundamentals
The article quotes the research team and Ms. Pacheco as using these findings to recommend that with nanoparticles, it is “prudent to limit their introduction into the environment.” This statement conveys a fundamental misunderstanding of the existing presence of nanoparticles in our world. Carbon nanotubes and C60 fullerene nanoparticles are produced as a by-product of most fossil fuel combustion, and sea salt on the surface of the ocean exists as a nanoparticle. We have been inhaling them and coming into contact with them ever since we discovered how to burn wood and walk to the beach-a fact that calls into question the entire culture of alarmism over the toxicity of nanomaterials. The difference is that the nanoparticles used in products have specifically been engineered to remain in the product and to be safe. If we truly want to limit our introduction of nanoparticles, our best bet would be to start using the nanocatalysts and ultra-light nano-materials that will cut down our fuel consumption.
To be fair, these issues are not isolated to this article, and I doubt there was any intent to mislead. Terms like “nano-particle” are a convenient shorthand, but there is no standard definition for them and they can be misleading. Nanotechnology holds significant promise and there are good reasons to be cautious as we proceed with it.
However, as the article admits, “there is not enough data yet” to warrant being alarmist. And we must not forget mass media’s penchant for alarmism. Scientists routinely demand precision and accuracy in research and engineering work. And it’s certainly time to make the same demand concerning communication with the public.
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Aatish Salvi is vice president of the NanoBusiness Alliance. He can be reached at [email protected].