Richard Feynman, Nobel prize winning physicist and science popularizer par excellence liked practical jokes, but I doubt he would have enjoyed watching people in the buff parade on Chicago’s Michigan Avenue with the title of one of his most famous lectures painted on their butt. There they were, exhibiting their derriers, adorned with the words “There’s Plenty of Room at the Bottom.” They were not exactly paying homage to Feynman’s famous lecture that introduced the concept of nanotechnology; they were protesting the use of the technology by the Eddie Bauer Company to make stain free pants. As if we didn’t have enough things to worry about, activists are now taking aim at nanotechnology, claiming that its risks have not been properly evaluated. So what is nanotechnology? Basically, it is the use of extremely small particles for practical purposes. How small? By consensus, at least one dimension of these particles must be less than 100 nanometers, a nanometer being one billionth of a meter. To put this into perspective, you would need a thousand of these particles side by side to make up the width of a human hair. And why is nanotechnology a field to itself? Because particles with such tiny dimensions behave very differently from their larger counterparts even though their chemical composition may be the same. To give a somewhat simplistic example, imagine holding a lump of coal. You could readily toss it from one hand to the other without any problem. Now if that lump were smashed into a fine powder, its properties would change dramatically. You couldn’t help inhaling the dust and it would probably produce a coughing fit. But it could also be used as a lubricant. When we are talking “nano,” we are talking about particles that are far smaller than this dust, in fact so small that individually they cannot even be seen.
Consider this example. Zinc oxide has long been used as a sunblock. This is the white stuff that has anointed many a lifeguard’s nose. It’s very good at absorbing ultraviolet light but is not very appealing esthetically. Enter nanotechnology. It is now possible to produce zinc oxide in particles so small that they appear transparent. Not only does this eliminate the chalky appearance, but a layer of such nanoparticles on the skin actually blocks ultraviolet light more effectively. Another fascinating application is in the production of self-cleaning windows. A layer of nano size particles of titanium dioxide deposited on glass serves two purposes. It absorbs ultraviolet light and produces free radicals which decompose dirt. It also has the effect of preventing water from beading. When rain hits the glass, instead of forming droplets, the water spreads into a thin transparent film. Stain resistant “nanopants” are another development. Here the effect is the opposite of that provided by nano titanium dioxide. Tiny carbon fibers are deposited on the surface of the fabric and these repel liquids, causing them to bead and roll off without staining. Why then are demonstrators opposed to this technology? They claim that the tiny nanoparticles can go through the skin or can be inhaled and potentially cause harm. That’s why they dropped their stain-resistant pants, hoping to expose the problem. The fact is that “nanotoxicology” is actually in full swing, and producers are ahead of the game. In this case testing has been done well before the products were introduced to the market place. The activists should pull up their pants and get on with their nanolives.
