Silver-based textiles may prove hazardous to the environment

According to an April 7 report in the Sacramento Bee, the University of California, Davis, may be on its way to uncovering a dark side to silver nanotechnology.

It is no secret that apparel makers and sock companies have been widely touting the benefits of silver nanotechnology as a “natural” means to kill bacteria that cause odor. Certainly, odor reduction is a plus, but researchers at UC Davis have discovered during initial research for a grant application that the silver nanoparticles, which can be as small as a billionth of a meter, can leach out of socks and clothing after only a few washings.

Subsequently, those silver nanoparticles are then free to travel into wastewater and, possibly, end up in the soil via leach lines from septic systems or in fertilizer derived from the sludge at sanitation facilities. As a result, they could target and possibly eradicate valuable microbes.

UC Davis is competing for a $25 million grant from the National Science Foundation to establish a search center. At the time of the news report, it had made the first cut and is one of 10 applicants being considered.

SNEWS® View: In a rush to be green — and tout products that provide human benefits via supposed natural means rather than chemical — SNEWS® wonders if, sometimes or perhaps more frequently than not, deeper thought regarding possible consequences gets pushed aside in favor of economic gain. This questioning of silver reminds us a bit of the rush to bamboo as a miracle plant for natural fibers in 2005, only to discover in 2006 that — oops — one of the favored ways of turning bamboo wood into fiber suitable for weaving was to submerge the wood fibers into sulfuric acid or lye, which has obvious human and environmental health consequences. Certainly, there are mechanical processes for performing the same task, but they are much more labor and time intensive and, consequently, not as popular.

The concern over silver is not a new one. Scientists called to light concerns over nanotechnology, including silver, in 2006 during a Washington, D.C., conference. Getting more specific regarding questions over silver in our wastewater, a fall 2007 article in OnEarth Magazine (www.onearth.org) quoted Patrick Lin, director of the Nanoethics Group based in San Luis Obispo, Calif., as saying: “The manufacturers say that nanosilver is the key ingredient to kill bacteria in your laundry, but in the same breath, they say (at least implicitly) that nanosilver won’t have a significant impact after it is released into the water system. Well, which is it — is nanosilver an effective killer or not?”

Science is calling for more testing, but is well short of calling for a moratorium on production of goods. What is known right now is that there is a vast unknown. Manufacturers are proceeding rapidly down the road of embracing technologies that are known and used in one application (presumably safely), but may not be appropriate for a separate and unrelated application and could possibly, as a result, cause environmental harm. Just because nanosilver is used successfully in medical products does not mean it is necessarily appropriate for mass production in clothing and socks, for example.

UC Davis hopes to find out. And so do we. In the meantime, perhaps we might all exercise a bit more restraint in the rush to embracing new technologies and methods in our headlong rush to be green? Just a thought.