They are bacteria-killers, more and more common in products we use every day and at least a million of them will fit on the head of a pin. But are silver nanoparticles safe?
Little is known about the health effects of these inventions.
“We have no idea how some of these structures interact in biological systems — nor do we understand the potential toxicological risks they impose on our environment,” says James Bonner, an associate professor in the Department of Environmental and Molecular Toxicology at North Carolina State University
An Environmental Protection Agency science panel began a four-day hearing Tuesday in Washington examining the hazards associated with the odor-ending nanosilver.
Those concerns will also be underscored this week when Swiss scientists release what they say is the first comprehensive study on the escape of silver nanoparticles from clothing to rivers, streams and lakes, often major sources of drinking water.
Textile manufactures are cranking out millions of pairs of sweet-smelling bras, panties, socks, undershirts and other clothing that are spiked with nanosilver, advertising the garments as containing odor and germ-fighting material.
In the Swiss study, being published this week in the American Chemical Society’s journal Environmental Science & Technology, the scientists measured the nanosilver particles released from a variety of brands of socks made from different textiles, finding that most of were relatively large and that as much as 35 percent of the total silver came out of the fabrics during the first wash.
Most filters in water treatment plants are unable to screen out the nano-sized particles of silver, which may be no thicker than 1/50,000th the width of a human hair.
“These results have important implications for the risk assessment of silver textiles and also for environmental fate studies of nanosilver,” said Dr. Bernd Nowack and his colleagues from the Swiss Federal Laboratories for Materials Testing and Research.
For decades, scientists have shown that silver in many forms has great medicinal effects, including being toxic to most bacteria, viruses, and fungi.
While silver is useful, there is growing concern that no one has yet completed, or, at least published research on whether nano-sized silver in the water may harm the environment or the people and animals who drink it.
While this study dealt with a clothes hamper of socks, to understand the potential size of the problem, consider that there are thousands of individual items being sold that tout nanosilver as an antibacterial agent.
The Internet is filled with hundreds of products from underwear for astronauts, campers and hikers, to thongs, frilly bras and hospital scrubs.
The anti-odor, anti-bacterial clothing is selling well around the world and new lines of products are being added almost weekly.
The Internet offers page after page of the latest nanosilver products for sale. One clothing website based in Wisconsin described its presentation as “scantily clad models who we can be sure smell as good as they look.”
But it’s infants and children that give marketers their biggest payday. They count on new parents’ fears of germs to sell an almost endless list of products that will kill the bugs on things their offspring may put in their mouths.
But nanosilver products didn’t slink quietly into the marketplace.
The Korean electronics manufacturer Samsung had a Hollywood-style gala to launch its “Silver Wash” clothes washer with a nanosilver-coated drum that it said it would kill over 600 different bacteria.
Most of the high end women’s and design magazines had slick ads proclaiming that the ‘Silver Wash’ “released 400 billion nanoscale silver particles during the wash and rinse cycles and achieved 99.9 percent sterilization of bacteria.’’ It boast leaving behind a residual silver coating on clothing “to keep it smelling fresh for up to 30 days.”
So when you think about what’s going out with the rinse water, think bigger than a few pair of socks.
Andrew Maynard, Chief Science Advisor for the Project on Emerging Nanotechnologies, warned Congress last year that hundreds of products with nanoparticles are on the market, with three to five new ones added every week.
“What we know at the moment is that silver does have the potential to cause environmental harm if released in sufficient quantities, and that silver used as nanoparticles might exacerbate the problem in some circumstances,” he told me this weekend.
He is concerned that current research won’t provide a clear picture of potential risks presented by nanoscale silver for some time.
“And it’s not even clear whether the right research is being funded – in other words, there’s a disconnect between where we need to be on nanosilver, and what we are doing to get there,” added Maynard, who’s at the Woodrow Wilson International Center for Scholars.
In June 2008, The International Center for Technology Assessment and a coalition of consumer, health, and environmental groups filed a petition with the EPA demanding the agency use its pesticide regulation authority to stop the sale of hundreds of consumer products now using nano-sized versions of silver.
No one involved in the nano safety fight could tell me of any products that EPA pulled off the market. But, under powers of the almost unpronounceable Federal Insecticide, Fungicide, and Rodenticide Act, EPA declared Samsung’s “Silver Wash” a pesticide.
The EPA’s nano Scientific Advisory Panel will be evaluating statements on the “Assessment of Hazard and Exposure Associated with Nanosilver.”
Here are three of the many topics they are likely to debate, or at least consider as they ponder what regulations this multi-billion dollar industry needs and will accept:
- An antibacterial agent like nanosilver is a pesticide. It kills bugs.
- Not only does nanosilver kill harmful bacteria, but it doesn’t distinguish between good and bad bacteria. This means it will also kill microbes that water treatment plants need to operate and that we need to live.
- The potential hazards associated with exposure to nano particles – both metals and chemicals – are likely to differ from the same substance that hasn’t been reduced in size.
The most common reply when nano scientists and marketers are asked about the safety of their almost invisible creations is something like: “Well, we know the toxicity limits for (insert chemical of your choice) Why should we test it just because we’ve made it smaller?”
Many toxicologists and public health specialists disagree.
“Unfortunately, that’s the mantra,” said PEN scientist Maynard. “One size fits all is not a viable concept when it comes to assessing risk or toxicity of any substance.”
Dr. Jennifer Sass, senior scientist and nano specialist for the Natural Resources Defense Council has long been concerned about the toxicity of nano particles.
In material she submitted to the EPA panel, Sass said that unless multiple, well-designed studies demonstrate otherwise, nanosized material should not be automatically declared safe.
Sass, who for years has studied EPA and industry’s testing for children’s exposure to toxic material, says that NRDC is particularly concerned about exposures to infants and children through the use of nanosilver and other nano-chemical antimicrobials.
Many who will attend the hearings or who submitted testimony believe passionately that no new government regulations are needed.
For example, some groups that sell cosmetics or nutritional or medical supplements made with silver are adamantly against EPA imposing any controls on silver products. They insist that nutritional supplements containing nanosilver have never been demonstrated to pose any threat to the environment.
Other federal and state agencies will be watching the outcome of the EPA’s effort.
Almost everyone sees the enormous actual and potential benefit to medicine, engineering and a hundred other fields from the advances in nanotechnology. But many people in government, public health and the nano industry worry that there must be some mechanism to weigh the benefits against what could be an enormous risk.