Book 'Em, Nano

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By Robert L. Wolke
Wednesday, January 24, 2007

I have been reading articles that question the safety of nanoparticles and the lack of oversight by the FDA. I saw some neat storage containers that keep produce fresh longer through the use of silver nanoparticles in the plastic. Can nanoparticles gravitate to food? Would that possibly endanger my health? What's the health risk here, and may I safely buy those nifty food storage containers?

Your health would not be compromised, but your pocketbook might be. Do you really want to spend $69.95 for a dozen plastic boxes to keep your broccoli in?

The theory is that the boxes kill bacteria and molds, allowing your fruits and vegetables to stay garden fresh for a long time. But I doubt it.

Nanoparticles -- sometimes as small as clusters of a few atoms -- are the latest weapon against America's endemic fear of germs. The prefix nano designates the one-billionth part of a measuring unit -- in this case, a meter -- just as milli means one-thousandth and micro means one-millionth. (Human hairs, to give you an idea of how small we're talking, range from about 50,000 to 180,000 nanometers in diameter.)

Over the past decade, nanotechnology has propelled biology, medicine, computing, electronics and many other fields into dazzling new realms. According to a study by the German market research firm Helmut Kaiser Consultancy, the world's food industry alone will command a $20.4 billion nanotechnology market by 2010.

Here is the basis of the claim that plastic containers made with engineered silver nanoparticles will keep your food fresh longer. The atoms of a nanoparticle, instead of being distributed throughout a large chunk of matter, are virtually all exposed on the surface, where they can react quickly and easily with adjacent substances. The chemical properties of nanoparticles can therefore be billions of times more powerful than those of the same material in bulk.

But why silver? For thousands of years, silver metal has been valued not only for its beauty but also for its apparent ability to help keep food and water from going bad. As recently as the early 20th century, people were putting silver coins in their bottles of milk to prolong its freshness. Today we know the reason: Silver atoms can actually kill bacteria, fungi, molds and even some viruses.

While we can't sprinkle nanoparticle pixie dust on our food, we can embed the nanoparticles in plastics. Plastics containing embedded silver nanoparticles are already being used to germ-proof toys, clothing, air fresheners, shoe liners, laundry detergents, washing machines, refrigerators -- and now, food storage containers.

Why do I doubt that these containers will work? For one thing, simply storing a fruit or vegetable in a nanoparticle-impregnated plastic box does not ensure that the spoilage bugs on the surface of the food will come in contact with actual silver atoms and bite the dust. Moreover, foods age and eventually rot not only because of microorganisms, but also because of oxygen and their own inherent enzymes.

Could these food storage boxes actually be harmful? No. Silver nanoparticles cannot migrate out of a polypropylene plastic container into your food; they're stuck firmly in the plastic.

While the FDA has not yet regulated the nano-silver food storage boxes from a toxicity point of view (there are still many unanswered questions), the Environmental Protection Agency recently proclaimed its concern about their possible environmental effects. Specifically, the EPA now requires any product claiming to kill germs with nanoparticles to provide scientific evidence that it poses no risk to the environment. Clearly, nobody yet knows all the answers.

The two leading retailers of silver-nanoparticle food storage containers are Sharper Image, which sells the FresherLonger Miracle Food Storage Container, and BlueMoonGoods, which sells the Fresh Box. A check of their Web sites shows that at this writing, Sharper Image has dropped its claim that FresherLonger eliminates more than 98 percent of bacteria, but BlueMoonGoods still asserts a reduction of "as much as 99.9 percent" for its Fresh Box. If there have been any independent tests of those claims, I have been unable to find them.

Labelingo: Larry Grant of Layton, Utah, writes: "Because Gilroy, Calif., labels itself the Garlic Capital of the World, I purchased a three-pack of garlic bulbs that were labeled as 'Gilroy's Best.' Imagine my surprise when I looked at the other side of the label and read, 'Product of China.' "

Robert L. Wolke (http://www.robertwolke.com) can be reached atwolke@pitt.edu.


© 2007 The Washington Post Company

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