Story Highlights• Silver long known to possess antibacterial and other beneficial properties
• Scientists harness metal's potential by shrinking it down to miniscule sizes
• Recent boom of consumer products that utilize small amounts of silver
• Some environmentalists worried that pervasive silver could disrupt ecosystems
By Greg Botelho
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WASHINGTON (CNN) -- Want to get rid of germs? Mold and grime? Smelly feet?
A growing number of scientists and businessmen say such a miracle substance exists, and in fact has for millions of years: Silver.
Innovative technologies and approaches have fueled an explosion of products taking advantage of silver's antibacterial properties. Consumers today can buy clothes, disinfectants, laundry machines and other items that utilize silver as an active agent.
"People have found out you can use [silver] far more effectively when you shrink it down," says Andrew Maynard, science adviser to the Project on Emerging Nanotechnologies, a joint effort of the Woodrow Wilson International Center for Scholars and Pew Charitable Trusts. "The range is quite incredible. It's as if a lightbulb has suddenly gone off."
Though silver is generally harmless to humans, environmentalists worry that excessive use of silver may allow it to seep into the environment, kill small organisms and disrupt the ecosystem.
"The projected uses are just too broad," says Jennifer Sass, a senior scientist at the National Resources Defense Council. "It is being used around the world in anything that you would want to kill bacteria ... It's reckless [and] many of the uses are frivolous."
While hardly the only antibacterial substance, Maynard says silver's ability to use multiple mechanisms to target germs otherwise resistant to antibiotics makes it especially effective -- and also may make it persist longer in the environment.
"There isn't a huge amount that is unknown [about silver]," says Maynard. "Is there any risk to the environment? That's a little bit fuzzier. There are issues out there [for which] there aren't easy answers."
Miniscule slivers of silver
In recent years, scientists have discovered cost- and time-effective ways to divide silver into miniscule particles, some just a few nanometers across. This not only lowers the price to buy and reproduce silver, but enhances its surface area, thus compounding its effectiveness.
"We're getting incredibly small, [which] gives us unprecedented control," Maynard says. "You can make it go a lot further."
The number of nanotechnology consumer products is surging, according to the Project on Emerging Nanotechnologies, which expects its inventory to surpass 500 such products this spring. And silver leads the way, surpassing all other elements, including carbon.
"It's not going to rival photography, jewelry and coinage in terms of overall demand, but the demand [for nanosilver] is growing," says Michael DiRienzo, executive director of The Silver Institute, an industry trade group. "We've known for centuries that silver has these special properties, [but] only recently have they found how it works."
One of the most well known applications is X-Static, which Noble Biomaterials president Bill McNally says is used in 1,000 products -- from sportswear and socks to hospital linens and military uniforms.
"Silver [is] antibacterial, it's used in every burn care center, and it's naturally anti-odor because it binds with anti-odor causative agents," said McNally, who co-founded Noble 11 years ago and calls the company "the pioneers of silver." "My mission was to create a product line that allowed you to take advantage of all those attributes."
Some try to utilize silver's properties in supplements and liquid forms, known as colloidal silver. Keith Moeller is the managing director of American Biotech Labs, which sells a supplement that uses a relatively sparse 10 parts of silver per million. He cites studies that claim the company's products can boost immune systems and fight malaria, salmonella, E. coli, bird flu and other ailments. Company president Bill Moeller testified to Congress in 2005 about the products' medical potential.
But the Food and Drug Administration has not found evidence that products containing colloidal silver are safe and effective. The agency targets companies that tout the medical efficacy of silver products.
With concerns, recognition of potential
"Over-the-top" advertising of silver irks Sass. If silver claims to kill microbes, she contends, it should be regulated like a pesticide -- with steps made to prevent its infusion into the environment.
But DiRienzo says, "To single out silver is unfair," given that it is viewed as less dangerous than most other metals and is being used in microscopic quantities.
"We're encouraging the federal government not to rush headfirst into regulations," he says, adding the silver industry has worked with the Environmental Protection Agency for decades and he doesn't oppose self-touting "germ killers" registering their products.
That said, most scientists concur that silver products hold significant potential. Even Sass, while opposing "broad releases that lead to obvious exposure," has no qualms about "targeted, controlled, restricted and important" uses, particularly medical applications.
For instance, silver ions are an active agent in QuikClot, a wound dressing for severe bleeding now being used by U.S. military forces and first responders. And McNally notes X-Static has been incorporated into many medical products, including hospital garments, sheets and bandages.
"Silver [provides] bacterial protection from the worst of the worst, as well as the ability to stimulate tissue growth," he said. "We have the ability to save people's lives."
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