The Not-So-Silver Lining of Your Anti-Microbial Outdoor Apparel

Nanotech_research_bed Simulated wetland used in silver nanoparticle research at Duke University. Photo: Benjamin Espinasse

In recent years, many outdoor apparel manufacturers have embraced a new range of anti-microbial textile coatings that are designed to inhibit the growth of bacterial and fungus that cause odors. Less stinky clothes means less stinky people, so it obviously has great marketing appeal—especially for clothing and socks that one might wear for numerous days in the backcountry. Plus, less stinky clothes means having to do less laundry, so that could add up to real energy and water savings for consumers.

But anti-microbial coatings might have a dark side. Many of these coatings use nanoparticles of silver—silver being the anti-microbial agent. A 2009 study showed that washing these textiles releases silver nanoparticles into waste water. From there, they could then enter the environment. And because silver is a known aquatic toxin, that concerns scientists. Now, a study conducted by researchers from Duke University and other institutions for the Center for the Environmental Implications of NanoTechnology, has revealed something even more troubling: Silver nanoparticles released into the environment can end up as a silver contaminant in terrestrial plants and aquatic animals. What's more, the silver was found in the organisms' offspring.

"You expose silver nanoparticles to one generation and it shows up in the next generation," says Martin Mulvihill, the executive director of U.C. Berkeley's Center for Green Chemistry and the author of a recent article about the study published in Environmental Health News. "It crosses the barrier between generations, and that is of the greatest concern. The Duke study shows silver nanoparticles persisted in the environment and underwent changes that might make it dangerous [to plants and animals]," he says.

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