The EPA is deciding whether to class an antimicrobial keychain as a pesticide, according to an article http://www.nytimes.com/2008/03/06/business/smallbusiness/06sbiz.html?pagewanted=2&ei=5087&em&en=2d26da9be22cce03&ex=1204952400 in the New York Times.

The product, called the handler - http://www.handlerusa.com/home.php, is basically a small, plastic pirate's claw impregnated with nanoscale silver particles. The particles prevent bacteria from getting a foothold on the hook. Have to go to the ATM and come into contact with filthy keys that other flu-ridden people have pawed? No problem, just pull out your hook.

Not so fast!

Apparently, the EPA thinks that, because of those pesky silver particles, the product may be considered a pesticide according to a 1947 law: "The law at issue the Federal Insecticide, Fungicide and Rodenticide Act, better known as FIFRA was conceived in 1947 to protect humans from agri-chemicals sprayed by the millions of gallons to kill weeds, plant viruses and bugs."

Since nanoparticles are so new, they have not been thoroughly evaluated for safety. And the Times notes that there may be some health risks, since those silver particles are so small: One of the biggest concerns with such particles is that they may easily penetrate the brain and other organs that larger particles cannot reach.

Moreover, some critics worry that the technology may contribute to the evolution of microbes resistant to silver poisoning. And some health experts say that constantly reducing exposure to troublesome microbes may eventually weaken the human immune system.

But even if the EPA does decide the handler is a pesticide, it is easy for the company to wriggle out of the regulations, by simply dropping the health claim that the product is antimicrobial.

As the E.P.A. interprets the regulation, a product is not "designed" to be a health-protecting antimicrobial -- and thus subject to registration requirements -- if it is not advertised as such.