Tag Archives: clothes washers

Sweating out silver nanoparticles

I’ve often wondered if the  silver nanoparticles, which coat the textiles used for clothing that doesn’t smell or need to be cleaned often, gets washed off by your sweat. As Michael Berger noted in his November 4, 2009 article on Nanowerk, researchers have found that silver nanoparticles do get washed off into the water,

Researchers in Switzerland have now examined what happens to these silver nanoparticle-treated textiles during washing. The scientists studied release of nanoparticles in laundry water from nine different textiles, including different brands of commercially available anti-odor socks. Studies like these will help address the question what the chances are of nanoparticles from nanofinished textiles being released into the environment.

“We found that the total released varied considerably from less than 1 to 45 percent of the total nanosilver in the fabric and that most came out during the first wash,” Bernd Nowack, head of the Environmental Risk Assessment and Management Group at the Empa-Swiss Federal Laboratories for Materials Testing and Research, tells Nanowerk. “These results have important implications for the risk assessment of silver textiles and also for environmental fate studies of nanosilver, because they show that under certain conditions relevant to washing, primarily coarse silver-containing particles are released.”

As it turns out, Thai researchers have recently discovered that sweat will also wash off those silver nanoparticles (from the news item on Nanowerk),

A recent study by researchers at National Nanotechnology Center (NANOTEC) in Thailand has provided the data on detecting silver released from antibacterial fabric products using artificial sweat as a model to represent the human skin environment.

“The amount of silver released from fabrics into artificial sweat was dependent upon the initial amount of silver coating, the fabric quality, pH and artificial sweat formulations “said Dr Rawiwan Maniratanachote, head of Nano Safety and Risk Assessment Lab. “The study could be useful to evaluate potential human risk when exposed to silver nanoparticles from textile materials.”

I guess the next couple of questions to be answered are: do the silver nanoparticles being washing off by your sweat penetrate your skin and/or do the silver nanoparticles wash off your skin and into the water supply?

German report on nanosilver toxicity and some thoughts on the US EPA silver nanomaterials consultation

More about nanosilver toxicology (see earlier posting about US EPA silver nanomaterials consultation) this week courtesy of an article by Michael Berger about a new report from a group of German researchers. From the article on Nanowerk,

Silver had already been recognized in ancient Greece and Rome for its infection-fighting properties but in modern times pharmaceutical companies made more money developing antibiotics. However, thanks to emerging nanotechnology applications, silver has made a comeback in the form of antimicrobial nanoparticle coatings for textiles, surgical instruments, lab equipment, floors or wall paints (see for instance: “Antibacterial nanotechnology multi-action materials that work day and night”).

The flip side of silver’s desired toxicity towards microbes is that it might have toxic effects for humans as well (“As nanotechnology goes mainstream, ‘toxic socks’ raise concerns”) and this has raised debate about the safety of nanosilver products. Although scientists have worked to reduce the toxicity of antimicrobial nanosilver in products, concerns remain.

Not helping to put these concerns to rest is a new report from a group of researchers in Germany that shows that toxicity of silver nanoparticles increases during storage because of slow dissolution under release of silver ions.

According to Epple [Matthias Epple, a professor for inorganic chemistry at the University of Duisburg-Essen], there is a general agreement that dissolved silver ions are responsible for the biological action that is especially pronounced against microorganisms. The lethal silver concentration of silver nanoparticles for human mesenchymal stem cells is about three times higher than that of silver ions (in terms of the absolute concentration of silver in a given solution).

The report has been published by the American Chemical Society in Chemistry of Materials. You can find an abstrect here, the full article is behind a paywall.

I was interested to note that the focus for the report is on the dissolution of nanoscale silver in water. By contrast, the US EPA consultation uses, as its starting point for the case study, nanoscale silver in an antibacterial spray. While laboratory researchers tend to focus on specifics such as the dissolution of  silver nanoparticles and ions, the EPA’s strategy allows for a 360o view. Theoretically, commenters could focus on anything from the production of the air spray, its own packaging, its use in various situations such as hospitals or food packaging, etc., and the various ways it dissipates into the environment, e.g. being washed off and ending up in the water supply.  This can lead to a comprehensive framework for future research activities examining more specific questions which provide answers that fit back into the framework.

Berger’s article reminds me of an October 29, 2009 news item on Science Daily about Swiss researchers, clothes washers, and nanosilver,

Scientists in Switzerland are reporting results of one of the first studies on the release of silver nanoparticles from laundering those anti-odor, anti-bacterial socks now on the market. Their findings may suggest ways that manufacturers and consumers can minimize the release of these particles to the environment, where they could harm fish and other wildlife.

They found that most of the released particles were relatively large and that most came out of the fabrics during the first wash. The total released varied from 1.3 to 35 percent of the total nanosilver in the fabric. Bleach generally did not affect the amount released. “These results have important implications for the risk assessment of silver textiles and also for environmental fate studies of nanosilver, because they show that under certain conditions relevant to washing, primarily coarse silver-containing particles are released,” the paper says.

The research report was published by the American Chemical Society’s Environmental Science and Technology journal. The abstract is available here, the full article is behind a paywall.

When is a nano-enabled product not nano-enabled?

Dietram Scheufele over at nanopublic has highlighted some research that David Berube (author of Nanohype—book and blog and professor at the University of North Carolina) and colleagues have published in Nanotechnology Law & Business (research article is behind a paywall). From Dietram’s July 3, 2010 blog posting (I’m unable to link to the specific post, so please scroll to or hunt for the date) about Berube’s research into the Project on Emerging Nanotechnologies’ (PEN) Consumer Products Inventory (CPI),

The article takes a critical look at the Project on Emerging Nanotechnologies (PEN) consumer product inventory. The inventory has been used widely as a gauge of the number and types of nano consumer products currently on the U.S. market.

… [the authors concluded]

“that the CPI is not wholly reliable, and does not have sufficient validity to justify its prominence as evidence for claims associated with the pervasiveness of nanotechnology on the U.S. and global markets. In addition, we caution researchers to approach the CPI with care and due consideration because using the CPI as a rhetorical flourish to amplify concerns about market intrusions seems unjustified.”

In other words, use the CPI with care. Unfortunately, I haven’t been able to read Berube’s paper but I did go to the Project on Emerging Nanotechnologies website and looked at the criteria for inclusion in the CPI where PEN clearly states the inventory’s limitations,

Selection of products

Most products in this inventory satisfy three criteria:

1. They can be readily purchased by consumers, and

2. They are identified as nano-based by the manufacturer OR another source, and

3. The nano-based claims for the product appear reasonable.

In every instance, we have tried to identify specific products from specific producers. However, since nanotechnology has broad applications in a variety of fields, we have included a number of “generic” products that you can find in many places on the market such as computer processor chips. These are clearly labeled in the inventory. In some cases, companies offer several similar nanotechnology-based products and product lines. To reduce redundancy, we have just included a few samples in this inventory and hope that they will provide an initial baseline for understanding how nanotechnology is being commercialized.

There are probably some products in the inventory which producers allege are “nano,” but which may not be. We have made no attempt to verify manufacturer claims about the use of nanotechnology in these products, nor have we conducted any independent testing of the products. We have tried to avoid including products that clearly do not use nanotechnology, but some have undoubtedly slipped through.

Finally, some products are marked “Archive” to indicate that their availability can no longer be ascertained. When these products were added to the inventory we included live links, but since then the company may have discontinued the product, gone out of business, removed a self-identifying “nano” claim or simply changed their web address. In these instances we have attempted to locate a cached version of the product website using The Internet Archive.

I imagine that despite PEN’s clearly statements some folks have referenced it carelessly hence the concern about using it as hype from Berube and his colleagues.

The bit about manufacturers removing the ‘nano’ claim hit home since I did some research into washers that use nanosilver. A friend was disturbed by a recent article about them and I remembered that the US EPA (Environmental Protection Agency) had made a special designation for these types of washers. As it turns out, I got it 1/2 right. From the December 4, 2006 article by Susan Morissey in Chemical and Engineering News,

Silver—claimed to be nanoparticles—employed to kill bacteria in washing machines will now be regulated as a pesticide, EPA announced late last month. Currently, washers that generate silver ions are classified as devices and are not required to be registered with EPA.

The products at issue are Samsung washing machines that are advertised as using silver ions to kill 99.9% of odor-causing bacteria. This technology, called SilverCare, generates ions by applying current to two silver plates housed next to the machine’s tub. The ions are then directed into the tub during the wash cycle.

“EPA has determined that the Samsung silver ion-generating washing machine is subject to registration requirements under the Federal Insecticide, Fungicide & Rodenticide Act,” according to an EPA statement. The agency decided to change the classification of the washer because it releases silver ions into the laundry “for the purpose of killing microbial pests,” the statement explains.

For its part, Samsung has pledged to comply with the change of policy. “Samsung has and will continue to work with EPA and state regulators regarding regulation of the silver washing machine,” the company says.

Several groups concerned about the environmental impact of nanoparticles of silver had asked EPA to reevaluate the way products containing such materials are regulated. For example, environmental group Natural Resources Defense Council (NRDC) noted in a letter to EPA that there are currently more than 40 products on the market in addition to Samsung’s washing machine that have made or implied claims of using nanoparticles of silver to kill bacteria.

NRDC praised EPA for taking what it called a “step in the right direction” by reclassifying nanosilver generated in a washer as a pesticide. The group also said this revised policy should lead to EPA reassessing other products that use nanoparticles of silver for their biocidal qualities.

A pesticide is not exactly a special designation but it certainly is unique as applied to clothes washers. The EPA announcement was made around the US Thanksgiving period (late November) according to a December 6, 2006 article by Scott E. Rickert in Industry Week. From Rickert’s article,

First, let’s backtrack and get the facts behind the headline. The trigger for the EPA decision was a Samsung washing machine. The “SilverWash” contains silver nanoparticles and claims that it helps to kill bacteria in clothes by releasing silver ions into the water during the wash.

Various U.S water authorities became concerned that discharged nanosilver might accumulate in the water system, particularly in wastewater treatment plants where beneficial bacteria are used to purify water of its toxins. This opinion means that nanosilver could be viewed as an environmental pesticide, requiring the product to be registered and tested under the Federal Insecticide, Fungicide and Rodenticide Act. In the words of EPA spokesperson Jennifer Wood, “The release of silver ions in the washing machines is a pesticide, because it is a substance released into the laundry for the purpose of killing pests.”

So what does this really mean to nano-industry? Specifically, we’re not sure yet. It will take several months for the final rules to be detailed in the Federal Register. But some of the early responses have me scratching my head.

One company has removed any reference to nanosilver from their marketing information for antimicrobial devices. Apparently, in the short run, that excludes them from any ruling. As Jim Jones, director of the EPA’s Office of Pesticide Programs, said, “Unless you’re making a claim to kill a pest, you’re not a pesticide.”

This is not a simple ‘good guy vs. bad guy’ situation. Defining nanotechnology, nanoparticles, nanomaterials, etc. is a work in progress which makes attempts to regulate products and production in this area an even earlier work in progress. This situation is not confined to the US or to Canada. In fact, it doesn’t seem to be confined to any one country, which makes the situation applicable globally.

There is work being done and changes instituted, for example, the EPA has announced (from the PEN website),

At an April 29 presentation to the Pesticide Programs Dialogue Committee in Washington, D.C. EPA’s William Jordan announced a new working definition of nanomaterials as “an ingredient that contains particles that have been intentionally produced to have at least one dimension that measures between approximately 1 and 100 nanometers.” In addition EPA is preparing a Federal Register Announcement due out in June which announces a new interpretation of FIFRA/regulations and proposes a new policy stating that the presence of a nanoscale material in a pesticide product is reportable under FIFRA section 6(a)(2) and applies to already registered products as well as products pending registration.

As well, statements from the NanoBusiness Alliance suggest (in a previous posting on this blog) that there is some support within the business community for thoughtful regulation. As to what thoughtful means in this context, I think that’s something we, as a a society, need to work out.