Not many, apparently. And one of the reasons is because 70 to 80 percent of the United States' population has not even heard of nanotechnology. Readers of science fiction might find that hard to believe, considering the frequency with which nanotech shows up in futuristic short stories and novels. Science fiction fans are clearly in the 20 to 30 percent of the public that have heard of nanotech. But what's so surprising about the polls is that nanotech is already here, and few people seem to realize it. The Woodrow Wilson International Center for Scholars estimates that as of February 2008, there were 607 nanotech-based consumer products on the market. This was up from 212 products in March 2007.
In fact, manufacturers are starting to throw the word "nano" around quite freely, even when they are vague on how nanotechnology is being used in their products. A quick Web search gives such "Technical Details" as "NanoTechnology The Future Cleaning Technology Today" and such product descriptions as "products are based upon unique polymer chemistry combined with cutting edge Nano Technologies." And of course there are the iPod Nano and now the Tata Nano, which bring the term "nano" into widespread use.
Interestingly, if you use Goggle Trends to see how many people use the search term "nanotechnology," you'll find that at the launches of the iPod Nano in 2005 and the Tata Nano in January 2008, there were surges in use of the search term "nano" but no corresponding increase in the search term "nanotechnology."
Given the rate at which products are appearing, the acceleration of scientific research, and the lack of knowledge or interest on the part of the general public, nanotech might possibly be the quietest technological revolution ever.
Here is a sampling of current products on the market:
Clothing, Textiles, and Wound Dressings
Silver nanoparticles embedded in the materials are resistant to fungi and bacteria. Their small size means a small volume of silver is used relative to the surface area of the particles that is in contact with microorganisms.
Sunscreens and Face Creams
Nanoparticles of zinc and titanium oxides absorb preferentially in the ultraviolet, and are both transparent and smooth.
Cleaning Products and "Green" Pesticides
Colloidal micelles are designed to penetrate materials and engulf hydrocarbon molecules that exist in dirt or the coatings of insects.
Nanoparticles of photoactivated catalysts (such as rhodium or titanium) are used in conjunction with UV light to produce free radicals that oxidize volatile organic compounds and kill microorganisms by oxidizing lipids in their cell walls.
Coatings for Glass, Plastics, and Ceramics
Hydrophilic (water-absorbent) nanoparticles and/or charged polymer chains work against surface tension, making water form a thin layer rather than beading up and fogging. Alternatively, a very thin layer of hydrophobic (water-repellent) molecules can cause water to form larger droplets, wicking up dirt in the process. These are often combined with photoactivated catalysts to form "self-cleaning glass."
Sealants for Stone Surfaces
The nano-sized hydrophobic molecules in the sealant are able to penetrate the surface of the material, giving it protection against moisture, cracking, and algae.
Carbon nanotubes can be used in composites to increase strength and flexibility and decrease weight.
Stain- and Wrinkle-Repellent Fabrics
Nano-sized "whiskers" stick to every fiber in the cloth, which creates a cushion of air around the fibers. Liquids bead up and roll off instead of being absorbed.
And of course the electronics industry is manufacturing semiconductors in smaller and smaller sizes, well into the nanorealm.
Regardless of public awareness, basic science on nanomaterials is forging full steam ahead. You just have to open any current major scientific journal to see current studies on nanomaterials. There is, in fact, now a specialized Nature journal dedicated to nanoscience.
Here are some recent examples from the scientific literature:
Super-strong, Super-thin Materials
A recent article in Science described the process of creating a new material by "gluing" clay platelets (about 100 nm on a side and 1 nm thick) together using a polymer in a bricks-and-mortar structure. (One nanometer, abbreviated "nm," is one millionth of a millimeter.) The layers form cooperative hydrogen bonds, and the result is a material that has extremely high stiffness and tensile strength but that is as light and thin as plastic wrap.
Bioremediation Using Nanoparticles of Iron
This study showed that iron oxide nanocrystals (12 nm in diameter) could be used to efficiently extract arsenic from ground water. The smaller the size of the particle, the larger the surface area relative to its volume and the more arsenic it can bind relative to its volume.
Bone cells were grown on carbon nanotubes that acted as a scaffold to direct the growing cells. The long-term goal is to create customized bones or to use the nanotubes to heal damaged bones.
Ultra-efficient Conversion of Heat to Electricity
Researchers found that silicon nanowires can be used to conduct electricity without also conducting heat. This means that they could theoretically be used to turn waste heat into useful energy—such as charging your cell phone from your body heat.
In terms of funding, nanotech is really big. The U.S. government is investing heavily in its future: $1.4 billion goes annually to nanotech research around the country. There are now major nanotech centers at many universities and national labs. Globally, the public and private sectors together spent over $12 billion in nanotech research and development in 2006.
But will nanotech pan out in a big and visible way? Despite the buzz over nanotech at the start of this century, it hasn't quite led to the immense changes in our lifestyles that were predicted early on. David Rejeski, director for the Project on Emerging Nanotechnologies, describes the situation:
Waiting. That feeling is creeping over the nanotechnology community: waiting for the "killer app" to burst into the commercial marketplace, into full public view before the glaring stage lights of the media.
Still, many nanotech experts are predicting a major nanotech explosion in the next decade, with exponential growth in products as "molecular manufacturing" becomes viable and easy. Lux Research estimates that $2.6 trillion worth of goods, amounting to 15 percent of global output, will use nanotech by 2014.
The Risks Versus the Perception of Risk
No article on nanotech safety can go without a reference to Bill Joy's famous piece in Wired in 2000. In it, he rails against nanotechnology, robots, and genetics because he sees them all as allowing power into the hands of individuals:
I think it is no exaggeration to say we are on the cusp of the further perfection of extreme evil, an evil whose possibility spreads well beyond that which weapons of mass destruction bequeathed to the nation-states, on to a surprising and terrible empowerment of extreme individuals.
But it has been eight years since he made those dire predictions, and life as we know it is much the same. Robotic AIs are not taking over the world, no crazy terrorist has engineered a virus to kill everyone in a particular genetic group, and nanotech has not yet reduced the entire biosphere to "gray goo."
Still, the next few years may well determine whether nanotech makes it, and a lot of that is predicated on whether its safety is accepted or rejected by the public. Genetically modified foods are an example of research that was not received well by the general public, with an enormous impact on the industry, especially in Europe.
According to Yale Law School professor Dan Kahan, "The U.S. public's perception of nanotechnology is up for grabs. . . . People who know little or nothing about 'nanotechnology' instantly react in an emotionally charged way to the concept, and their opinions divide along cultural lines as they learn more about it[.]"
Perceptions do matter. A report by ICF International, a global consulting firm, says that "perceptions of risk—not based on scientific evidence—may develop in the absence of definitive research and manifest themselves in a public backlash against nanotechnology."
According to the Hart poll, a little over half (51 percent) of people surveyed were unwilling to say whether the benefits of nanotech outweighed the risks. Another recent study showed that when asked about risks of nanotechnology, people tended to agree with the experts whose cultural values matched their own, regardless of what they actually knew or didn't know about nanotech.
As people gain greater awareness and understanding of nanotechnology, their expectations and knowledge will be increasingly managed, for good or bad. Public backlash, deserved or not, could result from one nanotech product going awry, or from the perception that investment in nanotech is a waste of money and resources. If, for instance, people associate nanotech only with face creams and bizarre images, then they might begin to perceive it as a frivolous technology.
Information about nanotech needs to get out into the public arena. But how to discuss nanotech in such a way that it does not cause a public alarm? There is growing discussion in the scientific communities about how to communicate with the public on scientific matters, especially ones that intersect with political issues and agendas. In a recent letter to Science, two scientists argue that since the general public is rarely motivated enough to weigh competing issues and arguments, scientists should "strategically avoid emphasizing the technical details of science when trying to defend it." Instead, they argue that scientists should learn to "frame" issues in terms of what the public cares about. In other words, forget the details; just tell them whether it's good or bad.
Whether people agree with this approach or not, however, is irrelevant at the moment, because there just aren't enough "details" yet.
The basic problem is that for a field as young and diverse as nanotech, the safety question is still really difficult to answer. Most studies conclude that "more work is needed." According to Andrew Maynard, science adviser for the Project on Emerging Nanotechnologies, "The more we know about nanomaterials' risks, the more we worry about what we don't know[.]"
One of the difficulties is that materials act much differently on a molecular scale than they do in bulk. Everyone knows, for instance, that gold is yellow and immutable. Only it's not when it's in the form of a nanoparticle with just a few dozen gold atoms. In that case, it is red. It is also highly chemically reactive. The smaller a thing, the more surface area it has relative to its volume—in other words, the more "edge" it has relative to "inside." This affects how a material bonds and shares electrons, and can change its fundamental properties like charge, magnetism, color, and melting point.
Another problem is that toxicity depends not just on dose but also on particle size. The difference between 10 nm and 100 nm, for instance, can cause particles to interact very differently with their environment. And the very properties that make nanoparticles particularly well suited for drug delivery or warfare—namely the fact that they are easily dispersed, absorbed through skin, ingested, or inhaled—also make them difficult to contain.
Nonetheless, several groups have started to tackle the difficult questions of nanotech safety. The Safer Nanomaterials and Nanomanufacturing Initiative at the University of Oregon, for instance, sponsors conferences on nanotechnology, and is heading the very ambitious project of creating a "library of nanoparticle knowledge" in order to thoroughly quantify the toxicity of every nanomaterial. The NIH Nanotechnology Characterization Lab is hoping to do something similar, serving as a "national resource and knowledge base for . . . nanotechnologies intended for cancer therapies and diagnostics." The FDA formed a nanotechnology task force last year to address regulatory and safety issues associated with nanomaterials and their first report came out in July 2007.
In July 2007, Consumer Reports published an article titled "Nanotech: Untold promise, unknown risk," a headline that succinctly summarizes the state of nanotechnology.
When you look at the potential range of applications, the list is impressive: alternative energy such as spray-on solar cells; consumer products such as stain-resistant fabrics; environmental cleanup such as bioremediation; medical applications in disease detection, treatment, and drug delivery; military applications such as sensors and weapons. If even a fraction of the imagined applications pan out, nanotech will have an immense impact in all areas of human life, from medicine to transportation to commerce to war.
For thousands of years, human engineering has measured its worth in terms of "how big": the largest cathedral, the tallest building, the longest wall. And in the last few decades, the measure of big has become even more sophisticated: the biggest network, the fastest computer, the most complex system. But the current century may bring the measuring stick of scientific achievement down to the atomic level, the realm of nanotechnology. It will be interesting to see how research, safety, perception of safety, and advertising all play out in the success or failure of nanotech in the coming years.
Footnotes and References
 The Cultural Cognition Project, led by Yale Law School, is studying the public response to nanotech, and in a survey in December 2006, they found that 81 percent of the public had heard either nothing at all or very little about nanotechnology: http://research.yale.edu/culturalcognition/content/view/110/89/. More recently a Hart Research survey in August 2007 found that number to be 70 percent: http://www.nanotechproject.org/news/archive/poll_reveals_public_awareness_nanotech/.
 The Woodrow Wilson Center runs the Project on Emerging Nanotechnologies, which maintains a database of consumer products using nanotech: http://www.nanotechproject.org/inventories/consumer/.
 A "Biobased Nanotechnology Concentrate" floor cleaner: http://www.amazon.com/1stenvirosafety-1st-Anyfloors-123-Nanotechnology/dp/B0006G7STO/
 Tata Motors recently unveiled the "Nano," the "People's Car." Although the connection to nanotechnology is tenuous, the car is definitely small: http://www.tatapeoplescar.com/tatamotors/.
 Nature Nanotechnology (http://www.nature.com/nnano/index.html) was started in October 2006.
 "Enhanced Thermoelectric performance of rough silicon nanowires," Nature, 2008, Vol. 451, p. 163. See also the ABC News coverage of the research: http://abcnews.go.com/Technology/GadgetGuide/Story?id=4173214&page=1.
 The National Nanotechnology Initiative (http://www.nano.gov/) describes federal funding for nanotech and gives a list of all nanotech centers.
 See, for instance, the winning entries for The 49th International Conference on Electron, Ion and Photon Beam Technology and Nanofabrication Bizarre/Beautiful Micrograph Contest: http://www.zyvexlabs.com/EIPBNuG/2005MicroGraph.html. My personal favorite is the nanotoilet.