Before You Brush …

Tempe, Ariz.—With nanosilver popping up as an antibacterial agent in everything from food storage containers to workout clothes, Kathleen Eggleson worries about neutralizing another bullet in the gun firing at bad germs.

Nanosilver, a super-small version of a substance that’s been used for centuries, is useful in legitimate medical settings, where it’s applied to burns and major wounds, said Eggelson, a researcher at the University of Notre Dame’s Center for Nano Science and Technology.

But in most people, she said, there’s ​“just no reason for these extreme hygiene practices.”

Manufacturers are using it more and more as an ingredient to kill germs. They use it as a lining in plastic food containers, for instance. They weave it in fibers in workout shirts or socks to kill the bacteria that makes you smell. They put in toothbrushes to help kill bacteria in your mouth.

And that might be overkill. Eventually, if people use too much of it, they might develop resistance — and then when they really need it, for instance in a burn bandage, nanosilver might not do its job. There’s also the issue of the bacteria themselves mutating into something that nanosilver can’t kill.

Eggelson outlined her concerns during a talk at the Third Annual Conference of the Society for the Study of Nanoscience and Emerging Technologies, being held this week in Tempe. The main sponsors are the Centers for Nanotechnology in Society, which are located at Arizona State University and the University of California, Santa Barbara.

Doctors and scientists are grappling with drug-resistant strains of bacteria, such as MRSA, and worry that the chemical triclosan—which is nearly ubiquitous in hand sanitizers, soaps and other germ-fighters — will add to the problem.

Nanosilver has the potential to be next in line, Eggleson said.

Leaving health and environmental concerns about nanosilver aside, she said, ​“the spread of silver resistance really is the threat.”

“When I do an Amazon.com search, I’m very concerned, because there are hundreds of products,” she said. ​“It’s very troubling. People don’t know what they’re doing.”

And there’s no real mechanism in place to police these products, Eggleson said. The U.S. Environmental Protection Agency has stepped in to stop companies (like this keyboard maker) from making claims to kill germs without testing or registering its formula as a pesticide. But if companies don’t make a specific claim, the EPA can’t touch them.

Nanotechnology leverages super-small particles (a nanometer is a billionth of a meter) to create new products. These materials can make bike frames lighter and stronger and sunscreen more transparent on the skin, as well as new medical instruments and medicines that can save lives.

There is broad agreement that nanomaterials have lots of potential for a wide variety of applications. But shrinking these substances can change their properties; scientists are struggling to figure out whether, how and why that shift can make them dangerous in the process.

Nanosilver has become particularly popular because of the anti-bacterial craze. While the silver industry points to its longtime use as evidence that it’s safe, scientists and the EPA are examining whether its proliferation poses any threat — and whether size matters in those calculations.

Eggleson said some nanosilver products might not pose much of a threat. For example, if the anti-stink sweat socks release their silver after a few washings, you’re unlikely to develop a resistance. But most people buying these products aren’t thinking about any of this — if they even understand what’s inside.

It’s important to start educating the public, she said, and not just about nanosilver and the potential for resistance. At a fundamental level, Eggleson said, people just don’t understand that not all germs are bad, which is why we slather on hand sanitizer and scour our counters with disinfecting wipes.

“The goal is to kill 100 percent” of bacteria with these kinds of treatments, Eggleson said. That’s way more than most of us need.