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The rapid emergence of nanotechnology suggests that size does, indeed, matter. It turns out that if you break common substances like silver and nickel into really, really tiny particles-measured in nanometers, which are billionths of a meter-they behave in radically different ways. For example, regular silver, the stuff of fancy tableware, doesn’t have any obvious place in sock production. But nano-size silver particles apparently do. According to boosters, when embedded in the fabric of socks, microscopic silver particles are “strongly antibacterial to a wide range of pathogens, absorb sweat, and by killing bacteria help eliminate unpleasant foot odor.” (By most definitions, a particle qualifies as “nano” when it’s 100 nanometers wide or less. By contrast, a human hair clocks in at about 80,000 nanometers in diameter.)

According to the Project on Emerging Nanotechnologies (PEN)-a joint venture of Virginia Tech and the Wilson Center-there are more than 1,600 nanotechnology-based consumer products on the market today. If SmartSilver Anti-Odor Nanotechnology Underwear sounds like a rather intimate application for this novel technology, consider that the PEN database lists 96 food items currently on US grocery shelves that contain unlabeled nano ingredients. Examples include Dannon Greek Plain Yogurt, Silk Original Soy Milk, Rice Dream Rice Drink, Hershey’s Bliss Dark Chocolate, and Kraft’s iconic American Cheese Singles, all of which now contain nano-size titanium dioxide. As recently as 2008, only eight US food products were known to contain nanoparticles, according to a recent analysis from Friends of the Earth-a more than tenfold increase in just six years.      

All of which raises the question of safety. Radically miniaturized particles are attractive to the food and textile industries for their novel properties. Nano-size titanium dioxide, for example, is used as a color enhancer-it makes white foods like yogurt and soy milk whiter, and brightens dark products like chocolate. But what

unintended effects might it have?

That’s where the nano story gets murky. Remarkably, the US Food and Drug Administration, which oversees the safety of the food supply, both 1) acknowledges that nanoparticles pose risks that are substantially different from those of their regular-sized counterparts, and 2) has done nothing to slow down their rapid move into the food supply.