Well this is embarrassing. I have been covering ecofashion and sustainable design for almost 15 years and I had no idea that silver nanoparticles are pretty much terrible for the environment.

Confession: I have two sports bras with silver in them — my thinking was that if they didn't get stinky so quickly, they would last longer, which would be an environmental and financial gain since I wouldn't have to replace them as often. With an almost-daily running/biking/hiking/movement practice, I go through a couple of bras a year, and it's not because I wear them out. It's because they end up stinking, even after they are washed. 

That's probably because, as NPR recently reported, a special kind of smelly bacteria proliferates on polyester especially. And polyester, in various combinations and mixes, forms the base of most modern quick-dry workout wear. Cotton doesn't harbor this stinky microbe—but it notoriously gets uncomfortably clammy minutes after you start sweating. I thought poly with the silver nanoparticles (which do seem to work to keep the stink out — the silver is an anti-bacterial) was the answer. 

But research has found that silver nanomaterials make their way — via the washing machine, where silver ions are released — into our water supplies. There, the silver ions are toxic to a variety of organisms. And if the sludge from the treatment plants is used as fertilizer often is — on agricultural fields — the results are even more far-reaching. (This process is more fascinating than it sounds, as detailed in this RadioLab episode.)

Rickard Ardvissen's doctoral thesis took a closer look an nanomaterials. "Clothing is considered to be a large source of nanosilver emissions already," Arvidsson told Phys.org. "If silver usage in clothing continues to increase, the consequences for the environment can be major.  For example, silver can accumulate in soil if sludge from waste water treatment plants is used as fertilizer, which can result in long-term damage to soil ecosystems."

The extremely informative Risk Bites video above agrees, detailing how silver ions are not likely to affect human health (in fact, some alt-health practitioners think it can be efficacious in small doses), but how they are definitely problematic for environmental reasons. 

Add to that the fact that silver nanoparticle protection against bacteria only lasts for about 10 or so washes, and you may (like I have) paid extra for fleeting de-stink protection. 

Guess I need to think of some kind of upcycling solution to my sports bra problem since I'm going to have to replace them anyway. 

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Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.