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Mae Wu’s Blog

Nanosilver Stinks

Mae Wu

Posted September 15, 2010

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No one wants to smell bad when they’re playing sports or camping, so everyone should go out and buy antibacterial, odor-fighting clothes. At least that’s what companies like HeiQ Materials Ag are betting on, by making antibacterial clothes and other textiles by treating them with nanosilver. Ignoring the silly idea that you have to smell pretty when you’re sweating, should we be allowing our clothes to be treated with this pesticide?

A month ago, EPA announced its plan to allow nanosilver to be registered as a pesticide for use as a preservative on textiles like clothing, towels, and bed sheets. NRDC submitted comments opposing EPA’s plans because it is illegal, irresponsible, and potentially dangerous to the public.

Silver is a well-recognized antimicrobial; it is very toxic to aquatic organisms (of all the metals, only mercury is more toxic), can bioaccumulate in ocean plants, and is persistent in the environment.  Nanosilver – or silver nanoparticles – works because it is designed to release silver ions, meaning people who wear them will be exposed to them, and that when these textiles are laundered, nanosilver will be washed into our waterways.  

When a company applies to register a pesticide, it must submit a specific list of data to be used by EPA to determine  whether the pesticide can be used without harming humans or the environment. Sometimes, EPA will ask the company to submit additional data; when it does, it can grant the company a time-limited “conditional registration” so the pesticide goes onto the market while the company works on developing this additional data. Then, EPA is supposed to look at this new data and decide whether the pesticide should continue to be registered.   

On paper, this process seems to be a fair way to collect newly required data and not punish the company. However, in reality, it is grossly misused. And at least in the case of nanosilver, EPA is using it illegally. As it turns out, EPA is proposing to allow the company to use nanosilver for the next 4 years while it develops and submits a host of missing data. The problem is that some of this data is legally required to be submitted as part of the initial application, not after. In essence, EPA is giving this company a four year free pass to generate data that EPA’s own regulations written 26 years ago have always required to be submitted upfront. For a pesticide that has some potentially devastating effects when released into the environment, and potentially damaging effects when absorbed by humans, EPA should be more discriminating about who gets a conditional registration. 

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Mike SinatraSep 15 2010 09:55 PM

You are a shill for the drug industry and have no idea what you are talking about. Those like you at the NRDC are paid handsomely to purport dangers that don't exist. Get a real job. Please. Get a real job. Create something. Invent. Don't scare people for no reason.

Timothy McLeanSep 16 2010 09:18 AM

Mae, it would be advisable for you to actually read the EPA report where it is clearly stated that there is enough evidence to suggest there is no harm using nanosilvers. EPA has registered over 40 nanosilver products during the last 50 years and effectively monitored these products for the same amount of time, without any negative remarks during this time. You are also seemingly unaware of the fact that it is NOT illegal for EPA to grant such approval but that this is done at the discretion of the agency. If you really want to do your homework as a sound environmentalist, think about the positive aspects of innovation leading to using less natural resources (silver) to achieve a good protection against bacteria. Then think about the massive hospital acquired infection rate and what to do with it. If you then know maths you will be able to compute that a harmless product which can save peoples lives may not be worth screaming negatively about after all.

Frank SinatraSep 16 2010 09:54 AM

Right on, Frank. There is no evidence that use of nanosilver as an antimicrobial in fabrics has any impact on fish or even reaches aquatic environments. There is no law that requires the EPA to collect any data on nanosilver. While any antimicrobial is classified as a "pesticide," the use of the term in this article is intended to scare and not to inform. Silver is a naturally occurring mineral in the environment, is not mutagenic and is not toxic to humans. Silverware has been used for generations without any ill effects. Antipersperants are likely to be much more harmful to humans and the environment than this use of nanosilver.

Mae WuSep 16 2010 11:40 AM

Thank you for reading my blog and taking the time to comment. There seem to be some misconceptions about our comments to EPA (which I linked to in my blog) on this issue. I’d like to respond to a couple of the points that yall have raised.

First, any pesticide that is distributed or sold in the US must first be registered by EPA under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), which requires that the registrant submit data on product chemistry, exposure, toxicology, and environmental impact. Nanosilver is a pesticide that is regulated under FIFRA, and EPA is required to collect data from the registrant in order to register the product.

Second, EPA is allowed to grant conditional registrations of pesticides when three criteria are met. 7 USC section 136a(c)(7)(C). For the reasons you’ll see detailed in our comments, those criteria have not been met and so EPA cannot grant the conditional registration.

Finally, silver and nanosilver could behave in very different ways because of the difference in sizes. This is why we want to make sure EPA has data on nanosilver, before it floods our shelves.

Jen SassSep 16 2010 11:49 AM

Thank you for your comments. As the NRDC scientist working on the nano issues, i'd like to respond to your technical concerns about our position.

In its assessment of nanosilver, the EPA relied too heavily on silver hazard data, not nanosilver data, to make its safety determination. This is contrary to the advice of its Scientific Advisory Panel (SAP) of independent technical experts, which stated that “there are several major differences that could potentially result in a distinct hazard profile for nanosilver” (SAP report at 10).

EPA’s over-reliance on silver hazard data is not scientifically supported, and is not consistent with the legal requirements for registering a new pesticide like nanosilver.

Further, EPA clearly recognized teh potential for harm from these uses of nanosilver, because it conditioned the registration on the submission of more data, including data on its potential mutagenicity or carcinogenicity (EPA Appendix A at 10).

Moreover, EPA acknowledged in its report that it expected human exposures to occur through workplace tasks making the nanosilver fabrics, as well as through normal wearing of the fabrics (EPA Appendix A at 10 and 13). EPA also stated that the use of nanosilver fabrics “may lead to surface water contamination that could impact fish, invertebrates, avian, and algal communities” (EPA Appendix A at 9)

And, there is some scientific evidence that the silver ions (the toxic component of silver) are released during normal washing. In a 2009 study, between 1% and 45% of the silver was released from one normal washing of treated clothing. (Geranio et al, 2009). EPA was aware of this study and references it in its assessment.

I hope that this helps to clarify the scientific support for our position.


Nanosilver released from treated socks:

Ref: L. Geranio, et al., "The Behavior of Silver Nanotextiles during Washing," Environ. Sci. Technol. (Sept. 2009).

The SAP report can be accessed here:

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