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Illumination magazine.
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BRIDGE OVER TROUBLED BACTERIA: Zhiqiang Hu stands atop a span above a ‘settling' basin at the Columbia treatment plant. Hu has shown how beneficial bacteria can suffer from nanosilvers in sewage.

Luoma, too, says the laws will have to be modified to fit nanomaterials. "It is likely that the approaches we have used traditionally to test the toxicity of materials do not work very well with nanomaterials," he says. "Chemical toxicity can be tested by dissolving the chemical in water and exposing a test species. Nanomaterials aggregate, change forms, stick to materials that are eaten, etc. They are much more complex to test, and again, the regulatory agencies do not yet have the methods to get around these difficulties."

Currently, most of the nanosilver products on the market are regulated by the EPA under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). That's because they tout silver's effectiveness at killing bacteria, a claim that categorizes them as a pesticide.

The act makes it illegal for anyone to sell, distribute or use a pesticide unless it is registered with the EPA, except for emergencies and certain minimum-risk pesticides. As silver meets neither of these exemptions, one might assume that the hundreds of nanosilver products on the market have passed the registration process.

But that's not the case. In fact, Dale Kemery, an EPA press officer, says the EPA "has neither received an application nor approved any pesticide product that contains a nanomaterial, including silver."

This seems to suggest nano-product manufacturers are out of compliance, but Kemery will not say so. Neither will he say whether the EPA has taken action against any manufacturers of nanosilver products.

"We don't discuss whether we have investigations ongoing or not," he explains. "We do this to protect the integrity of any possible ongoing investigations."

Kemery will say that in many cases, manufacturers of nanosilver products can avoid registration if they make no antimicrobial claims because, strangely enough, a product's claims usually have more bearing on its pesticide classification than do its components.

As Kemery explains, "Products not making a pesticidal claim would not be subject to FIFRA unless the active ingredients are inherently pesticidal in nature and have no other significant commercially valuable use as distributed or sold, other than use for pesticidal purpose."

Though this loophole may provide a pass to some nanosilver products, most are making antimicrobial claims of some sort. In May 2008, a coalition of consumer, health and environmental groups joined the International Center for Technology Assessment -- a self-described "nanotech watchdog" based in Washington D.C. -- to file a legal petition with the EPA. It "demanding the agency use its pesticide regulation authority to stop the sale of numerous consumer products now using nano-sized versions of silver."

While the petition itself cites hundreds of studies to build its case for potential harm, the press release regarding the petition references only two: a 2008 Arizona State University study documenting nanosilver "escapes" from laundered nanosilver-enhanced socks, and Hu's study.

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