EPA Releases Draft Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray

The EPA recently released a draft of its "Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray" which you can download here.  The document is 323 pages long and has 6 chapters: (i) Introduction; (ii) Introduction to Silver and Nanoscale Silver; (iii) Life-Cycle Stages; (iv) Fate and Transport in Environmental Media; (v) Exposure, Uptake, and Dose; and (vi) Characterization of Effects.

In two chapters most pertinent to our readers, the document discusses the possible EHS ramifications of the manufacturing and use of nanoscale silver disinfectants over a wide-range of issues.  Regarding Life-Cycle Stages, the document covers five primary product stages: feedstocks; manufacturing; distribution and storage; use; and disposal.  Similarly, regarding fate and transport in the environment, the document discusses air, terrestrial, and aquatic systems and factors that effect transport and fate in each media.

Overall , the document appears to mirror the approach used in EPA's prior draft case study on nanoscale titanium dioxide used in drinking water systems and in sunscreens which was published in 2009. 

Written comments on the draft are due to EPA by September 27, 2010.


EPA Set to Rule on FIFRA Nanosilver Petition in June

Inside EPA reports today that a "senior policy adviser for EPA's Office of Pesticide Programs, said EPA would issue in June a long-awaited response to a 2008 activist petition asking the agency to regulate nanoscale silver under FIFRA."  The article also mentions that EPA intends to define nanoscale ingredients for FIFRA purposes 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."

IEEE Blogger Comments on Nanosilver Article

Earlier today, an IEEE blogger commented on a nanosilver article we previously re-published on this cite.   The original article was written by the Silver Nanotechnology Working Group and was first published on the University of Massachusetts, Amherst's InterNano website (where I am Contibuting Editor for Environmental, Health and Safety and Regulation). 

Dexter Johnson comments on the Nanoclast blog of IEEE's Spectrum website:

"In what must come as a blow to NGOs around the world it turns out that the material that has fueled much of their indignation about nanotechnology, nanosilver, has not only been 'rationally manufactured, regulated, and used commercially for over a century with no significant adverse environmental, health, and safety effects', but also the EPA has specifically been looking at nanosilver as far back as the 1950s."

Working Group Makes Important Contribution to EPA's Scientific Advisory Panel on Nanosilver

This article was contributed by Dr. Rosalinda Volpe, Executive Director, Silver Nanotechnology Working Group (SNWG) and originally appeared on the National Nanomanufacturing Network's InterNano website earlier today.  It is licensed under Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported.

On November 3 – 6, 2009 the US Environmental Protection Agency (EPA) held a Scientific Advisory Panel (SAP) meeting in Arlington, Virginia to discuss the “Evaluation of Hazard and Exposure Associated with Nanosilver and Other Nanometal Oxide Pesticide Products.”[1] The meeting was well attended. Over seventy-five people from industry, regulatory, public interest, and academic sectors attended the meeting over three days. EPA received presentations and comments from the SAP panel members during the course of the meeting, as well as six presentations during the Public Comment period, and also received over 560 written comments which can be found on EPA’s website.

One group—The Silver Nanotechnology Working Group (SNWG)[2] —made a detailed presentation[3] to EPA supporting a fundamental regulatory consideration previously overlooked by many in attendance: nanosilver has been rationally manufactured, regulated, and used commercially for over a century with no significant adverse environmental, health, and safety effects. SNWG explained that nanosilver—often called by other names such as "colloidal silver" or "millimicron silver"—has been used in a wide range of consumer applications such as swimming pool treatments and drinking water filters with an established record under FIFRA of regulated and safe use dating as far back as the 1950’s. Thus, SNWG believes that nanosilver is not a “new” material requiring some type of special regulation and EPA needs to look beyond general conceptions of nano terminology and consider the broader established regulatory record of nanoscale silver products within the Agency. Simply put, SNWG believes that calls for treatment of nanosilver as a new material requiring development of expensive new test regimes and discriminatory regulation are difficult to justify.

Moreover, SNWG explained at the meeting that a detailed look at the history of silver within EPA shows that the toxicological studies that form the center of EPA’s existing general hazard limits for silver are derived from historical data from nanoscale silver materials and not conventional (bulk) silver as is often mistakenly assumed. For example, SNWG’s careful examination of EPA’s public registration database[4] for silver over a period of 6 decades revealed:

  • The very first registered silver product was a colloidal nanosilver algaecide product that has been safely used by millions of consumers for over 50 years (registered since 1954).
  • Every EPA silver registration between 1970 and 1990 was either a colloidal nanosilver or nanosilver-composite product.
  • The very first NON-nanosilver product registered by EPA was not registered until 1994.
  • An overall analysis reveals that today over 50% of all EPA registered silver products are in fact based on nanoscale silver.

Based on its analysis, SNWG took the formal position that EPA has a range of existing regulatory structures that have successfully addressed silver materials across the size spectrum for over 5 decades. Additionally, EPA has not any incidents of significance on the Agency’s formal incident reporting database (EPA OPP IDS) – indicating that thorough monitoring of real-life use supports the safety of these products.

The SWNG congratulated EPA for its record of successful monitoring and risk management for these materials despite different terminologies being used throughout this time period. Indeed, SNWG pointed out that with nanosilver there is perhaps more historical data and evidence of safe use than for many other regulatory materials, and the EPA has the opportunity to assess nanosilver products with confidence given this long history of safe use under existing EPA regulatons.

The SNWG is hopeful that the EPA and the other meeting attendees will examine SNWG’s position and supporting information in more detail to confirm that nanosilver has been successfully regulated for decades. If sufficient consideration is given, SNWG believes that EPA will conclude that there is no need to “fix” a regulatory process that is not “broken,” but has worked exceedingly well for decades in the case of nanosilver.


1.  EPA Scientific Advisory Panel meeting, Arlington VA (November 3 - 6, 2009).

2.  SNWG is an industry effort intended to foster the collection of data on silver nanotechnology in order to advance the science and public understanding of the beneficial uses of silver nanoparticles in a wide-range of consumer and industrial products.

3.  SNWG “Evaluation of Hazard and Exposure Associated with Nanosilver and Other Nanometal Oxide Pesticide Products”, Presentation to Scientific Advisory Panel (November 4th, 2009).

4.  NPIRS Public.

EPA Takes Aim at Anitmicrobial Products Under FIFRA

In this article, we note a couple of recent EPA enforcement actions against manufacturers allegedly making unsubstantiated antimicrobial claims for their products – much like occurred in the IOGEAR computer keyboard/mice episode in 2008.  Although these products do not purport to use nanoscale materials, the alleged claims for these products are similar to those made by manufacturers for certain nano-based antimicrobial products. Thus, our readers may be interested in EPA’s actions.

The EPA issued a press release today stating that the parent company of North Face camping and outdoor gear faces up to $1,000,000 in fines for allegedly making unsubstantiated health-related claims for almost 70 of its shoe products using Agion silver ion technology. The EPA press release states:

“At issue were more than 70 styles of footwear that incorporated an AgION silver treated footbed. The company sold the products making unsubstantiated claims that the footwear would prevent disease-causing bacteria. Specifically, The North Face made the following public health claims about the footwear on-line and on product packaging:  • ‘AgION antimicrobial silver agent inhibits the growth of disease-causing bacteria’ • ‘Prevents bacterial and fungal growth’ • Continuous release of antimicrobial agents”

The fines are being sought by EPA under the Federal Insecticide Fungicide and Rodenticide Act which prohibits unsubstantiated public health claims regarding unregistered products.

From Agion’s website: “Agion technology operates at the surface of a product through the controlled release of silver ions which attack microbes and inhibit their growth in three different ways. We offer a variety of silver-based technologies to suit various manufacturing and product requirements.” 

In another press release, EPA publicized a complaint it filed “against Peoria, Ariz.-based Granite Marketing, Inc. for the alleged sale and distribution of an unregistered pesticide in violation of the Federal Insecticide, Fungicide and Rodenticide Act. The EPA is seeking up to $5,200 in civil penalties from Granite Marketing, Inc., located at 8190 W. Deer Valley Road, for offering for sale the unregistered antimicrobial pesticide known as Titania Antibacterial System.”


EPA Scientific Advisory Panel to Discuss Nanoscale Silver at Public Meeting

A much valued contributor from CyberRegs provided us with the following information from the Federal Register that may be of interest to readers:

There will be a 4-day consultation meeting of the Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (FIFRA SAP) to consider and review a set of scientific issues related to the assessment of hazard and exposure associated with nanosilver and other nanometal pesticide products.

DATES: The consultation meeting will be held on November 3 - 6, 2009, from approximately 8:30 a.m. to 5:00 p.m. The consultation meeting will be held at the Environmental Protection Agency, Conference Center, Lobby Level, One Potomac Yard (South Bldg.), 2777 S. Crystal Dr., Arlington, VA 22202.

Comments. The Agency encourages that written comments be submitted by October 20, 2009 and requests for oral comments be submitted by October 27, 2009. Mail: Office of Pesticide Programs (OPP) Regulatory Public Docket (7502P), Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460-0001.

FOR FURTHER INFORMATION CONTACT: Joseph E. Bailey, DFO, Office of Science Coordination and Policy (7201M), Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone number: (202) 564-2045; fax number: (202) 564-8382; e-mail address:



New Edition of Nanotechnology Law Report

Here is the Summer 2009 edition of Nanotechnology Law Report.  The newsletter contains the below-listed articles (and more):

  • EPA Issues Significant New Use Rules for Carbon Nanotubes
  • Are Nanoparticles Released by Cutting or Compounding Nano-Composites?
  • Annual Nano TiO2 Production Estimated at 44,000 Metric Tons
  • Are Nano Consumer Products Headed Underground?
  • Oversight of Next Generation Nanotechnology
  • Regulating Nanotechnologies
  • More Interesting Nano-Regulatory Developments
  • Nano Tug of War
  • Pumpkins & Nanoparticles
  • Green Nano
  • NanoBiotech 2009
  • Take two silver nanoparticles and call me in the morning
  • International Approaches to the Regulatory Governance of Nanotechnology
  • ETUC Resolution on Nanotechnologies and Nanomaterials
  • Private Spending on Nano Exceeds Government Spending
  • EMERGNANO Released

Interesting Nano-Regulatory Developments

Inside U.S. Trade reports three interesting nano-regulatory developments: (i) the "EPA has signaled that it may soon decide to regulate nano-silver as a pesticide under " FIFRA; (ii) the "EPA may rule favorably on some points" raised in the 2008 citizen's petition filed by 14 advocacy groups seeking more restrictive regulation of nanoscale silver; and (iii) Congresswoman Kathy DahlKemper (D-Pa) on the House Science and Technology Committee "is pursuing a Cosmetics Safety Bill that would require registration of cosmetics containing nanomaterials."

Nanotechnology Law Report -- July 2008

Nanotechnology Law Report -- July 2008

Nano-Silver EHS Backgrounder

With all of the interest in nanosilver generated by the recent EPA petition filed by the International Center for Technology Assessment, I thought I would post some background material on EHS issues surrounding silver.  A couple of disclaimers: the material is not comprehensive, and you might see parts of it again in "Nanotechnology Law and Policy" which should be published by Thomson-West legal publishers sometime in 2009 (if I can keep pace with the production schedule).


Silver (CASRN 7440-22-4) is a naturally occurring metal. It is usually found in extremely low concentrations in natural waters. “Humans are exposed to small amounts of silver from dietary sources.” “Silver levels of less than 0.000001 mg silver per cubic meter of air (mg/m3), 0.2-2.0 parts silver per billion parts water (ppb) in surface waters, such as lakes and rivers, and 0.20-0.30 parts silver per million (ppm) in soils are found from naturally occurring sources.” A 50 year old person has “an average retention of 0.23-0.48 g silver.”

Silver production in 1999 was estimated at 15.5 million kilograms world-wide, with Mexico and the US leading the list of producers. It is estimated that approximately 2.5 million kgs of silver in various forms is lost to the environment in the US every year, and that 29% of that amount is released to water and 68% to land. The most prevalent release routes are purportedly from smelting operations, photographic processing supplies, manufacturing of electrical components and wires, coal combustion, electroplating operations, and cloud seeding. NIOSH estimates that 70,000 people are exposed to silver in the workplace each year and inhalation is the most important route of exposure.

People and Animals. Silver has exhibited no known toxic effects to humans. According to the EPA, human health effects from breathing, eating, and/or drinking silver are "unknown." However, if you eat, drink, or breathe enough of it, your skin may turn a blue-gray color. This permanent cosmetic condition called “argyria” is not harmful to health. It results from silver depositing in the dermis layer of skin.   Breathing high levels of silver dust may cause breathing and respiratory problems, throat irritation, or stomach pain – as with other types of particulate matter.  Silver is not a known human carcinogen, but has been shown to cause cancer when inserted in lab animals under certain conditions. There are few, if any, toxicity animal studies based on oral or respiratory silver intake. “Tests in animals show that silver compounds are likely to be life-threatening for humans only when large amounts (that is, grams) are swallowed and that skin contact with silver compounds is very unlikely to be lifethreatening.”  Some occupational studies intimate that exposure to silver may cause kidney problems, although more research is needed on this issue. 

Silver Ions.  Monovalent silver ions are very rare in the natural environment. “The acute toxicity of silver to aquatic species varies drastically by the chemical form and correlates with the availability of free ionic silver.” “For freshwater fish, the acute toxicity of silver is caused solely by silver ion interacting with the gills . . .” “On the basis of available toxicity test results, it is unlikely that bioavailable free silver ions would ever be at sufficiently high concentrations to cause toxicity in marine environments.” “About 95% of the total silver [lost to water in the environment] is removed in publicly owned treatment works from inputs containing municipal sewage and commercial photprocessing effluents, and effluents contain less than 0.07 ug ionic silver/litre.”

Drinking Water. The federal government has issued guidelines concerning the maximum level of silver allowed in drinking water (Maximum Contaminant Level – MCL): long term exposure is limited to 0.1 mg/L (previously 0.05mg/L), and short term exposure (1-10 days) is limited to 1.142 mg/L. The silver MCL was first promulgated by the United States Public Health Service in 1962 before the Environmental Protection Agency was ever formed. Silver was included on the original list on the basis of epidemiological data and the fact that it was used as an antimicrobial. The epidemiological data was based on exposures to medicinal silver and exposures through mining and metalworking. In 1989 EPA proposed changing the MCL for silver from 0.05 mg/L to 0.09 mg/L because the only potential human health concern was from argyria. “The proposal was finalized, using an CML of 0.1 mg/L, on January 30, 1991.”

Surface Water.  Silver in surface water tends to settle down into the sediment. “Silver can remain attached to oceanic sediments for about 100 years under conditions of high pH, high salinity, and high sediment concentrations of iron, manganese oxide, and organics.” Silver levels in pristine surface water in unpolluted areas are approximately 0.01 μg /L and approximately 0.01 - 0.1 μg/L in urban and industrialized areas. The federal government regulates silver in surface water through the Federal Water Pollution Control Act (aka/ Clean Water Act) -- 33 U.S.C. § 1251. “The silver criteria contains values to protect human health from ingestion of contaminated aquatic organisms and maximum acceptable concentrations to protect organisms that live in freshwater and salt water from toxic effects. The human health part of the silver criteria was drawn directly from the drinking water MCL. Criteria for the protection of aquatic life, on the other hand, were derived using a newly developed set of guidelines that called for extensive laboratory test data. The values are given as total recoverable silver.”  The freshwater criteria maximum concentration (CMC) for silver is (3.2) 100mg/L, and the saltwater CMC is (1.9).

Air. Silver is not considered an air pollutant harmful to public health or environment under the National Ambient Air Quality Standards mandated by the Clean Air Act. Purportedly “[t]reatment of air emissions containing silver is not a concern as atmospheric emissions rarely approach the federal threshold limit value for occupational exposure of 0.01 mg/m3.”

Workplace. Workplace exposures to silver present unknown/unquantified health risks to humans. Most occupational exposures to silver are purportedly through photographic processing chemicals (dermal) or inhalation of silver dust particles from the ambient air. OSHA has set the maximum air quality standard for silver at 0.01 mg/m3 based on an 8 hour workday and 40 hour workweek.

Regulation of silver hazardous waste. Resource Conservation and Recovery Act (RCRA) is designed to (in part) prevent leaching of hazardous concentrations of particular toxic constituents into groundwater, and looks back to Primary Drinking Water Standards. Any waste that contains 100 times the amount of the relevant constituent is considered a hazardous waste. The “100 times” level was designed to compensate for the dilution of materials as they pass through soil when headed for ground water. Note, howeverm that the ACRA standard does not track the 1997 amendment to the drinking water standard. Since the original drinking water standard for silver was is 0.05mg/L, the maximum allowable limit is 5.0 mg/L for RCRA purposes. Wastes containing silver at this level or above are labeled as “hazardous wastes” under RCRA and are subject to further regulation under that Act. “Under CERCLA, silver-bearing hazardous wastes are designated as hazardous substances with a reportable quantity (RQ) equal to 1 pound (.454 kg).” Any release that exceeds the RQ in a 24-hour period must be reported to the National Response Center.

Select Bibliography:

“Toxicological Profile for Silver,” Agency for Toxic Substances and Disease Registry, U.S. Public Health Service (December 1990).

P.D. Howe, et al., “Concise International Chemical Assessment Document 44: Silver and Silver Compounds: Environmental Aspects,” World Health Organization (2002).

US EPA Integrated Risk Management System (IRIS), Silver (CASRN 7440-22-4), http://www.epa.gov?IRIS/subst/0099.htm.

 “25 Years of the Safe Drinking Water Act: History and Trends.”

Many states also regulate silver. Some state standards are more restrictive than EPA standards. See, e.g., “The Regulation of Silver in Photographic Processing Facilities,” Kodak Environmental Services, J-124 (1996).

T. Purcell, et al., “Historical Impacts of Environmental Regulation of Silver,” Environmental Toxicology and Chemistry, Vol. 18, No.1, pp. 3-8, 1999.

Aquatic life testing guidelines can be found at Fed. Reg. 45:79341 – U.S. EPA. 1980. “Guidelines for determination of ambient water quality for the protection of aquatic organisms and their uses.”

65 C.F.R. 31682

“The Regulation of Silver in Photographic Processing Facilities,” Kodak Environmental Services, J-124 (1996).

US EPA, Solid Waste and Emergency Response (5305W), RCRA Photo Processing, EPA530-K-99-002, January 1999.

Environmental Pollution from Nanosilver Socks?

A recent study by two Arizona State University researchers found that socks made of fabric incorporating nanoscale silver may potentially release that silver into wash-water.

T. Benn, et al., "Nanoparticle Silver Release into Water from Commercially Available Sock Fabrics," Environmental Science & Technology, Vol. 42, at 4133-4139 (2008).

Why put silver in your socks?  Because it is a well-known antimicrobial agent and microbes cause sock odor.  Kill the microbes, and your feet smell fresh.  At least that's the marketing angle. 


Several environmental NGOs, however, are concerned with whether silver might be released from the socks, enter the wash-water and waste-water streams, and keep on killing microbes. While you may not want microbes in your socks, they are a vital part of the ecosystem. The authors theorize that "[t]he ubiquitous use of commercial products containing n-Ag could potentially compromise the health of many ecosystems." (This is yet another twist to the Samsung Silver Care washing machine controversy a couple of years ago).

As for the socks themselves, the researchers selected pairs from Sharper Image, Fox River, Arctic Shield, Zeusah, and AgActive "based on the manufacturers' claims that the socks contained nanoparticles of silver. " We checked the advertising for ourselves, and only Arctic Shield and AgActive London actually make nanosilver claims, while Fox River and Zeusah make general silver and/or silver ion claims. As for the Sharper Image socks, the company is in the final stages of bankruptcy and is closing its stores. Its new owner may or may not continue direct sales through its catalog and the internet. No work on whether they will continue to sell socks at all.

Perhaps the most interesting thing about the advertising was efficacy claims:

"Your feet feel and smell fresher for longer."
"Stay fresh no matter how long you wear them."
"You can wear our socks for days on end and they won't smell."
"Just by wearing [our] socks we guarantee no more foot odor."
Testimonial: "I bought some of [your] socks for my nephew when he came to stay with me for the holiday. His feet always smelled but with the new socks, the smell is all gone. I am very happy."
Testimonial: "I wore them three days and there was no smell at all."
Regarding the test itself, the socks were first analyzed for their nanosilver content. Three of the six socks contained silver particles in the 100-500 nm range; only one contained silver particles in the traditional nanoscale range (under 100 nm). The socks were then washed three times in ultra-pure distilled laboratory water for 24 hour or 1 hour periods using an orbital shaker/agitator. No soaps or detergents were used. The researchers analyzed the resulting wash-water.

To cut a long story short, the researchers found that "at least some of the n-Ag is released into the wash-water as nanoparticles; not just as dissolved ionic silver."

As for total silver release, three of the six socks were found to have leached silver into the wash-water. (Sharper Image, Fox River, AgActive London). During the three 24 hour tests, the AgActive socks released a total of 19 of their 20 micrograms of silver, the Fox River socks released 165 of their 31,241 micrograms of silver, and the Sharper Image socks released 1578 of their 1845 micrograms of silver. In the three, one hour tests, the Sharper Image socks released 1020 micrograms of silver, and the Fox River socks released 390 micrograms of silver.

Interestingly, socks washed in plain old tap water did not release near as much silver as those washed in the ultra-pure, distilled, laboratory water.

UPDATE: First EPA Regulation of Nanotechnology?

Since first being reported in the Washington Post, and relayed here, more information concerning EPA's proposed regulation of nanosilver under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) has been uncovered.

As initially reported, the EPA's Office of Pollution Prevention reversed its course from earlier statements, and ultimately decided to regulate nanosilver under the FIFRA.  EPA reasoned that because manufacturers were producing products containing nanosilver as a method of killing bacteria, such uses were properly the province of the FIFRA as a pesticide.  Nanosilver is found in several products available today, including food containers, shoes, air fresheners, and bandages.  The concern is that the silver may pose a threat to aquatic systems as a bio-accumulative toxin.

Upon further research into EPA's announcement, it has been determined that EPA plans to issue a Federal Register notice that will explain the requirements for using nanosilver as an anti-bacterial agent.  Greenwire is reporting that the rule will be issued "within the next few months."  It is expected that those falling under this new rule will need to show that the nanosilver additive will not pose an environmental risk when placed into commerce.  However, as reported in the November 23, 2006 Washington Post article, EPA states that to be subject to FIFRA regulation, there has to be a claim that the product will "kill pests" in order for it to be a pesticide.  Consequently, products containing nanosilver may not be subject to FIFRA regulation absent a claim that the product kills bacteria, viruses, or the like.

The most important piece of information to come out of this subsequent research is the knowledge that EPA will indeed begin regulating nanomaterials, and plans to do so soon.  Silver is already regulated under the FIFRA in several products as a pesticide, so for EPA to regulate forms of nanosilver is potentially a new step.  The Federal Register notice should provide additional details as to how nanosilver will be regulated under the FIFRA and the procedures EPA will use in determining which uses are subject to regulation and which are not.  It is important to note that nanomaterials are not currently regulated, however it appears as though regulation is now imminent, starting with nanosilver in anti-bacterial uses.