Tag Archives: US Environmental Protection Agency

Cleaning up water polluted by agricultural fertilizers

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Researchers at Rice University (Texas, US) have announced a new catalyst for cleaning nitrites from water polluted by agricultural fertilizers (from the Rice University November 25, 2013 news release ,[also on EurekAlert]),

Chemical engineers at Rice University have found a new catalyst that can rapidly break down nitrites, a common and harmful contaminant in drinking water that often results from overuse of agricultural fertilizers.

Nitrites and their more abundant cousins, nitrates, are inorganic compounds that are often found in both groundwater and surface water. The compounds are a health hazard, and the Environmental Protection Agency places strict limits on the amount of nitrates and nitrites in drinking water. While it’s possible to remove nitrates and nitrites from water with filters and resins, the process can be prohibitively expensive.

There is a map illustrating the problem,

CAPTION: Many areas of the United States are at risk of contamination of drinking water by nitrates and nitrites due to overuse of agricultural fertilizers. CREDIT: USGS

CAPTION: Many areas of the United States are at risk of contamination of drinking water by nitrates and nitrites due to overuse of agricultural fertilizers.
CREDIT: USGS Courtesy: Rice University

Here’s more about these new catalysts designed to ‘scrub’ water clean (from the news release; Note: Links have been removed),

.. Michael Wong, professor of chemical and biomolecular engineering at Rice and the lead researcher on the new study [says] “Our group has studied engineered gold and palladium nanocatalysts for several years. We’ve tested these against chlorinated solvents for almost a decade and in looking for other potential uses for these we stumbled onto some studies about palladium catalysts being used to treat nitrates and nitrites; so we decided to do a comparison.”

Catalysts are the matchmakers of the molecular world: They cause other compounds to react with one another, often by bringing them into close proximity, but the catalysts are not consumed by the reaction.

In a new paper in the journal Nanoscale, Wong’s team showed that engineered nanoparticles of gold and palladium were several times more efficient at breaking down nitrites than any previously studied catalysts. The particles, which were invented at Wong’s Catalysis and Nanomaterials Laboratory, consist of a solid gold core that’s partially covered with palladium.

Over the past decade, Wong’s team has found these gold-palladium composites have faster reaction times for breaking down chlorinated pollutants than do any other known catalysts. He said the same proved true for nitrites, for reasons that are still unknown.

“There’s no chlorine in these compounds, so the chemistry is completely different,” Wong said. “It’s not yet clear how the gold and palladium work together to boost the reaction time in nitrites and why reaction efficiency spiked when the nanoparticles had about 80 percent palladium coverage. We have several hypotheses we are testing out now. ”

He said that gold-palladium nanocatalysts with the optimal formulation were about 15 times more efficient at breaking down nitrites than were pure palladium nanocatalysts, and about 7 1/2 times more efficient than catalysts made of palladium and aluminum oxide.

I gather this team will be doing more work before promoting the use of gold-palladium nanocatalysts (from the news release),

Wong said he can envision using the gold-palladium catalysts in a small filtration unit that could be attached to a water tap, but only if the team finds a similarly efficient catalyst for breaking down nitrates, which are even more abundant pollutants than nitrites.

“Nitrites form wherever you have nitrates, which are really the root of the problem,” Wong said. “We’re actively studying a number of candidates for degrading nitrates now, and we have some positive leads.”

Here’s a link to and a citation for the paper,

Supporting palladium metal on gold nanoparticles improves its catalysis for nitrite reduction by Huifeng Qian, Zhun Zhao, Juan C. Velazquez, Lori A. Pretzer, Kimberly N. Hecka and Michael S. Wong. Nanoscale, 2014, Advance Article DOI: 10.1039/C3NR04540D First published online 30 Oct 2013

This paper is behind a paywall.

Nanosilver—US Environmental Protection Agency (EPA) gets wrist slapped over nanosilver decision in textiles while Canadian Broadcasting Corporation (CBC) publishes article about nanosilver

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I have two pieces about nanosilver today (Nov. 11 ,2013). The first concerns a Nov. 7, 2013 court ruling in favour of the Natural Resources Defense Council (NRDC) stating that the US Environmental Protection Agency (EPA) failed to follow its own rules when it accorded HeiQ Materials (a Swiss textile company) permission to market and sell its nanosilver-based antimicrobial fabric treatment in the US. From the NRDC’s Nov. 7, 2013 press release,

Court Ruling in NRDC’s Favor Should Limit Pesticide Nanosilver in Textiles

In a decision handed down today, the court said the EPA had improperly approved the use of nanosilver by one U.S. textile manufacturer [HeiQ Materials; headquarteed in Switzerland]. The court vacated the approval and sent it back to the agency for reevaluation. The lawsuit has been closely watched as a test case for the growing use of nanotechnology in consumer products.

“The court’s ruling puts us a step closer toward removing nanosilver from textiles,” said Mae Wu, an attorney in NRDC’s Health Program. “EPA shouldn’t have approved nanosilver in the first place. This is just one of a long line of decisions by the agency treating people and our environment as guinea pigs and laboratories for these untested pesticides.”

NRDC sued the U.S. Environmental Protection Agency in early 2012 to limit the use of nanosilver out of a concern for public health. Today the 9th U.S. Circuit Court of Appeals agreed with a key point NRDC raised: that the EPA didn’t follow its own rules for determining whether the pesticide’s use in products would be safe.

Beginning in December 2011, EPA approved the company HeiQ Materials to sell nanosilver used in fabrics for the next four years and required the company to provide data on toxicity for human health and aquatic organisms. In early 2012, NRDC filed a lawsuit against EPA seeking to block nanosilver’s use, contending, among several points, that the agency had ignored its own rules for determining the safety of nanosilver.

The key part of today’s Ninth Circuit ruling addressed EPA’s determination that there is no risk concern for toddlers exposed to nanosilver-treated textiles. The agency’s rules state that if there’s an aggregate exposure to the skin or through ingestion at or below a specific level, there is a risk of health concerns. But the Ninth Circuit found that the EPA had data showing that nanosilver was right at the level that should have triggered a finding of potential risk, but approved the pesticide anyway. That led to the Ninth Circuit vacating EPA’s approval and sending it back down to the agency for reevaluation.

Published in July 2013 (?), Nate Seltenrich’s article, Nanosilver: Weighing the Risks and BenefitsNanosilver: Weighing the Risks and Benefits, for the journal, Environmental Health Perspectives (EHP) [published with support from the National Institute of Environmental Health Sciences, National Institutes of Health, U.S. Department of Health and Human Services]) provides some insight into the court case and the issues,

It takes a special sort of case to spur attorneys into a debate over the drooling habits of toddlers. Yet that’s where lawyers from the Natural Resources Defense Council (NRDC), the U.S. Environmental Protection Agency (EPA), and Swiss chemicals company HeiQ found themselves in January 2013 as they debated in a federal appeals court the extent to which 1-year-olds and 3-year-olds chew, salivate, and swallow.1

At issue in the NRDC’s suit against the EPA, which is still awaiting ruling, was whether the agency was right in granting a conditional registration in December 2011 to a nanosilver-based antimicrobial fabric treatment manufactured by HeiQ.2 The EPA’s risk assessment was based in part on assumptions about exposure of 3-year-olds by sucking or chewing on nanosilver-laced textiles such as clothing, blankets, and pillowcases.

NRDC lawyer Catherine Rahm, however, begged to differ with the agency’s methods. In the January hearing, she argued that the agency record shows infants are more likely than any other subset of children to chew on fabrics that could contain the pesticide, and that if the agency were to recalculate its risk assessment based on the body weight of a 1-year-old, nanosilver concentrations in HeiQ’s product could result in potentially harmful exposures.

It’s an obscure but critical distinction as far as risk assessment goes. And given the implications for HeiQ and other companies looking to follow in its footsteps, the case has landed at the center of a prolonged conflict over the regulation of nanosilver and the growing deployment of this antimicrobial ingredient in a variety of commercial and consumer products.

Yet regardless of which side prevails in the case, the truth about nanosilver is not black and white. Even the loudest voices joining the NRDC’s call for strict regulation of nanosilver concede that context is key.

Seltenrich goes on to recount a little of the history of nanosilver and provide a brief a relatively balanced overview of the research. At the end of the article, he lists 37 reference documents and offers links, should you wish to research further. For anyone interested in HeiQ, here’s the company website.

The second nanosilver news item is from the CBC (Canadian Broadcasting Corporation( online. In an article by Evelyn Boychuk titled, Silver nanoparticle use spurs U.S. consumer database; Database tracks growing number of consumer goods containing nanomaterials, these nanoparticles are discussed within the context of a resuscitated Project on Emerging Nanotechnologies (PEN) Consumer Products Inventory (CPI), which was mentioned in my Oct. 28, 2013 posting titled: Rising from the dead: the inventory of nanotechnology-based consumer products. The articles offers an easy introduction to the topic and refers to a database of silver,nanotechnology in commercial products (complementary to the larger CPI).

Life-cycle assessment for electric vehicle lithium-ion batteries and nanotechnology is a risk analysis

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A May 29, 2013 news item on Azonano features a new study for the US Environmental Protection Agency (EPA) on nanoscale technology and lithium-ion (li-ion) batteries for electric vehicles,

Lithium (Li-ion) batteries used to power plug-in hybrid and electric vehicles show overall promise to “fuel” these vehicles and reduce greenhouse gas emissions, but there are areas for improvement to reduce possible environmental and public health impacts, according to a “cradle to grave” study of advanced Li-ion batteries recently completed by Abt Associates for the U.S. Environmental Protection Agency (EPA).

“While Li-ion batteries for electric vehicles are definitely a step in the right direction from traditional gasoline-fueled vehicles and nickel metal-hydride automotive batteries, some of the materials and methods used to manufacture them could be improved,” said Jay Smith, an Abt senior analyst and co-lead of the life-cycle assessment.

Smith said, for example, the study showed that the batteries that use cathodes with nickel and cobalt, as well as solvent-based electrode processing, show the highest potential for certain environmental and human health impacts. The environmental impacts, Smith explained, include resource depletion, global warming, and ecological toxicity—primarily resulting from the production, processing and use of cobalt and nickel metal compounds, which can cause adverse respiratory, pulmonary and neurological effects in those exposed.

There are viable ways to reduce these impacts, he said, including cathode material substitution, solvent-less electrode processing and recycling of metals from the batteries.

The May 28, 2013 Abt Associates news release, which originated the news item, describes some of the findings,

Among other findings, Shanika Amarakoon, an Abt associate who co-led the life-cycle assessment with Smith, said global warming and other environmental and health impacts were shown to be influenced by the electricity grids used to charge the batteries when driving the vehicles.
“These impacts are sensitive to local and regional grid mixes,” Amarakoon said.  “If the batteries in use are drawing power from the grids in the Midwest or South, much of the electricity will be coming from coal-fired plants.  If it’s in New England or California, the grids rely more on renewables and natural gas, which emit less greenhouse gases and other toxic pollutants.” However,” she added, “impacts from the processing and manufacture of these batteries should not be overlooked.”
In terms of battery performance, Smith said that “the nanotechnology applications that Abt assessed were single-walled carbon nanotubes (SWCNTs), which are currently being researched for use as anodes as they show promise for improving the energy density and ultimate performance of the Li-ion batteries in vehicles.  What we found, however, is that the energy needed to produce the SWCNT anodes in these early stages of development is prohibitive. Over time, if researchers focus on reducing the energy intensity of the manufacturing process before commercialization, the environmental profile of the technology has the potential to improve dramatically.”

Abt’s Application of Life-Cycle Assessment to Nanoscale Technology: Lithium-ion Batteries for Electric Vehicles can be found here, all 126 pp.

This assessment was performed under the auspices of an interesting assortment of agencies (from the news release),

The research for the life-cycle assessment was undertaken through the Lithium-ion Batteries and Nanotechnology for Electric Vehicles Partnership, which was led by EPA’s Design for the Environment Program in the Office of Chemical Safety and Pollution Prevention and Toxics, and EPA’s National Risk Management Research Laboratory in the Office of Research and Development.  [emphasis mine] The Partnership also included industry partners (i.e., battery manufacturers, recyclers, and suppliers, and other industry groups), the Department of Energy’s Argonne National Lab, Arizona State University, and the Rochester Institute of Technology

I highlighted the National Risk Management Research Laboratory as it reminded me of the lithium-ion battery fires in airplanes reported in January 2013. I realize that cars and planes are not the same thing but lithium-ion batteries have some well defined problems especially since the summer of 2006 when there was a series of li-ion battery laptop fires. From Tracy V. Wilson’s What causes laptop batteries to overheat? article for How stuff works.com (Note: A link has been removed),

In conjunction with the United States Consumer Product Safety Commission (CPSC), Dell and Apple Computer announced large recalls of laptop batteries in the summer of 2006, followed by Toshiba and Lenovo. Sony manufactured all of the recalled batteries, and in October 2006, the company announced its own large-scale recall. Under the right circumstances, these batteries could overheat, potentially causing burns, an explosion or a fire.

Larry Greenemeier in a Jan. 17, 2013 article for Scientific American offers some details about the lithium-ion battery fires in airplanes and elsewhere,

Boeing’s Dreamliner has likely become a nightmare for the company, its airline customers and regulators worldwide. An inflight lithium-ion battery fire broke out Wednesday [Jan. 16, 2013] on an All Nippon Airways 787 over Japan, forcing an emergency landing. And another battery fire occurred last week aboard a Japan Airlines 787 at Boston’s Logan International Airport. Both battery failures resulted in release of flammable electrolytes, heat damage and smoke on the aircraft, according to the U.S. Federal Aviation Administration (FAA).

…

Lithium-ion batteries—used to power mobile phones, laptops and electric vehicles—have summoned plenty of controversy during their relatively brief existence. Introduced commercially in 1991, by the mid 2000s they had become infamous for causing fires in laptop computers.

More recently, the plug-in hybrid electric Chevy Volt’s lithium-ion battery packs burst into flames following several National Highway Traffic Safety Administration (NHTSA) tests to measure the vehicle’s ability to protect occupants from injury in a side collision. The NHTSA investigated and concluded in January 2012 that Chevy Volts and other electric vehicles do not pose a greater risk of fire than gasoline-powered vehicles.

Philip E. Ross in his Jan. 18, 2013 article about the airplane fires for IEEE’s (Institute of Electrical and Electronics Engineers) Spectrum provides some insight into the fires,

It seems that the batteries heated up in a self-accelerating pattern called thermal runaway. Heat from the production of electricity speeds up the production of electricity, and… you’re off. This sort of things happens in a variety of reactions, not just in batteries, let alone the Li-ion kind. But thermal runaway is particularly grave in Li-ion batteries because they pack a lot more power than the tried-and-true metal-hydride ones, not to speak of Ye Olde lead-acid.

It’s because of this very quality that Li-ion batteries found their first application in small mobile devices, where power is critical and fires won’t cost anyone his life. It’s also why it took so long for the new tech to find its way into electric and hybrid-electric cars.

…

Perhaps it would have been wiser of Boeing to go for the safest possible Li-ion design, even if it didn’t have quite as much oomph as possible. That’s what today’s main-line electric-drive cars do, as our colleague, John Voelcker, points out.

“The cells in the 787 [Dreamliner], from Japanese company GS Yuasa, use a cobalt oxide (CoO2) chemistry, just as mobile-phone and laptop batteries do,” he writes in greencarreports.com. “That chemistry has the highest energy content, but it is also the most susceptible to overheating that can produce “thermal events” (which is to say, fires). Only one electric car has been built in volume using CoO2 cells, and that’s the Tesla Roadster. Only 2,500 of those cars will ever exist.” Most of today’s electric cars, Voelcker adds, use chemistries that trade some energy density for safety.

The Dreamliner (Boeing 787) is designed to be the lightest of airplanes and using a more energy dense but safer lithium-ion battery seems not to have been an acceptable trade-off.  Interestingly, Boeing according to Ross still had a backlog of orders after the fires.

I find that some of the discussion about risk and nanotechnology-enabled products oddly disconnected. There are the concerns about what happens at the nanoscale (environmental implications, etc.) but that discussion is divorced from some macroscale issues such as battery fires. Taken to absurd lengths, technology at the nanoscale could be considered safe while macroscale issues are completely ignored. It’s as if our institutions are not yet capable of managing multiple scales at once.

For more about an emphasis on scale and other minutiae (pun intended), there’s my May 28, 2013 posting about Steffen Foss Hansen’s plea to revise current European Union legislation to create more categories for nanotechnology regulation, amongst other things.

For more about airplanes and their efforts to get more energy efficient, there’s my May 27, 2013 posting about a biofuel study in Australia.

US Environmental Protection Agency (EPA) releases Application of Life-Cycle Assessment to Nanoscale Technology: Lithium-ion Batteries for Electric Vehicles

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There’s more about the Application of Life-Cycle Assessment to Nanoscale Technology: Lithium-ion Batteries for Electric Vehicles (final report) in the Apr. 30, 2013 news item on Nanowerk (Note: Links were removed),

The final report for the life-cycle assessment (LCA) of current and emerging energy systems used in plug-in hybrid and electric vehicles conducted by the DfE [Design for the Environment]/ORD [Office of Research and Development] Li-ion Batteries and Nanotechnology Partnership is now available. The LCA results will help to promote the responsible development of these emerging energy systems, including nanotechnology innovations in advanced batteries, leading to reduced overall environmental impacts and the reduced use and release of more toxic materials.

This partnership was led by EPA’s Design for the Environment (DfE) Program, in the Office of Pollution Prevention and Toxics, and the National Risk Management Research Laboratory, in EPA’s Office of Research and Development.

US EPA’s Partnership for “Application of Life-Cycle Assessment to Nanoscale Technology: Lithium-ion Batteries for Electric Vehicles” webspace describes the project and the report,

The partnership conducted a screening-level life-cycle assessment (LCA) of currently manufactured lithium-ion (Li-ion) battery technologies for electric vehicles, and a next generation battery component (anode) that uses single-walled carbon nanotube (SWCNT) technology.

A quantitative environmental LCA of Li-ion batteries was conducted using primary data from both battery manufacturers and recyclers–and the nanotechnology anode currently being researched for next-generation batteries.

This type of study had not been previously conducted, and was needed to help grow the advanced-vehicle battery industry in a more environmentally responsible and efficient way. The LCA results are expected to mitigate current and future impacts and risks by helping battery manufacturers and suppliers identify which materials and processes are likely to pose the greatest impacts or potential risks to public health or the environment throughout the life cycle of their products. The study identifies opportunities for environmental improvement, and can inform design changes that will result in the use of less toxic materials and reduced overall environmental impacts, and increased energy efficiency.

The opportunities for improving the environmental profile of Li-ion batteries for plug-in and electric vehicles identified in the draft LCA study have the potential to drive a significant reduction of potential environmental impacts and risks, given that advanced batteries are an emerging and growing technology.

The study also demonstrates how the life-cycle impacts of an emerging technology and novel application of nanomaterials (i.e., the SWCNT anode) can be assessed before the technology is mature, and provides a benchmark for future life-cycle assessments of this technology.

For anyone who’s interested the final report (all 126 pp) of the LCA is available here.

Soybeans and nanoparticles

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They seem ubiquitous today but there was a time when hardly anyone living in Canada  knew much about soybeans.  There’s a good essay about soybeans and their cultivation in Canada by Erik Dorff for Statistics Canada, from Dorff’s soybean essay,

Until the mid-1970s, soybeans were restricted by climate primarily to southern Ontario. Intensive breeding programs have since opened up more widespread growing possibilities across Canada for this incredibly versatile crop: The 1.2 million hectares of soybeans reported on the Census of Agriculture in 2006 marked a near eightfold increase in area since 1976, the year the ground-breaking varieties that perform well in Canada’s shorter growing season were introduced.

Soybeans have earned their popularity, with the high-protein, high-oil beans finding use as food for human consumption, animal rations and edible oils as well as many industrial products. Moreover, soybeans, like all legumes, are able to “fix” the nitrogen the plants need from the air. This process of nitrogen fixation is a result of a symbiotic interaction between bacteria microbes that colonize the roots of the soy plant and are fed by the plant. In return, the microbes take nitrogen from the air and convert it into a form the plant can use to grow.

This means legumes require little in the way of purchased nitrogen fertilizers produced from expensive natural gas-a valuable property indeed.

Until reading Dorff’s essay, I hadn’t early soybeans had been introduced to the Canadian agricultural sector,

While soybeans arrived in Canada in the mid 1800s-with growing trials recorded in 1893 at the Ontario Agricultural College-they didn’t become a commercial oilseed crop in Canada until a crushing plant was built in southern Ontario in the 1920s, about the same time that the Department of Agriculture (now Agriculture and Agri-Food Canada) began evaluating soybean varieties suited for the region. For years, soybeans were being grown in Canada but it wasn’t until the Second World War that Statistics Canada began to collect data showing the significance of the soybean crop, with 4,400 hectares being reported in 1941. In fact, one year later the area had jumped nearly fourfold, to 17,000 hectares…

As fascinating as I find this history, this bit about soybeans and their international importance explain why research about soyboans and nanoparticles is of wide interest (from Dorff’s essay),

The soybean’s valuable characteristics have propelled it into the agricultural mix in many parts of the world. In 2004, soybeans accounted for approximately 35% of the total harvested area worldwide of annual and perennial oil crops according to the Food and Agriculture Organization of the United Nations (FAO) but only four countries accounted for nearly 90% of the production with Canada in seventh place at 1.3% (Table 2). Soymeal-the solid, high-protein material remaining after the oil has been extracted during crushing-accounts for over 60% of world vegetable and animal meal production, while soybean oil accounts for 20% of global vegetable oil production.

There’s been a recent study on the impact of nanoparticles on soybeans at the University of California at Santa Barbara (UC Santa Barbara) according to an Aug. 20, 2012 posting by Alan on the Science Business website, (h/t to Cientifica),

Researchers from University of California in Santa Barbara found manufactured nanoparticles disposed after manufacturing or customer use can end up in agricultural soil and eventually affect soybean crops. Findings of the team that includes academic, government, and corporate researchers from elsewhere in California, Texas, Iowa, New York, and Korea appear online today in the Proceedings of the National Academy of Sciences.

The research aimed to discover potential environmental implications of new industries that produce nanomaterials. Soybeans were chosen as test crops because their prominence in American agriculture — it is the second largest crop in the U.S. and the fifth largest crop worldwide — and its vulnerability to manufactured nanomaterials. The soybeans tested in this study were grown in greenhouses.

The Aug. 20, 2012 UC Santa Barbara press release has additional detail abut why the research was undertaken,

“Our society has become more environmentally aware in the last few decades, and that results in our government and scientists asking questions about the safety of new types of chemical ingredients,” said senior author Patricia Holden, a professor with the Bren School [UC Santa Barbara’s Bren School of Environmental Science & Management]. “That’s reflected by this type of research.”

Soybean was chosen for the study due to its importance as a food crop –– it is the fifth largest crop in global agricultural production and second in the U.S. –– and because it is vulnerable to MNMs [manufactured nanomaterials]. The findings showed that crop yield and quality are affected by the addition of MNMs to the soil.

The scientists studied the effects of two common nanoparticles, zinc oxide and cerium oxide, on soybeans grown in soil in greenhouses. Zinc oxide is used in cosmetics, lotions, and sunscreens. Cerium oxide is used as an ingredient in catalytic converters to minimize carbon monoxide production, and in fuel to increase fuel combustion. Cerium can enter soil through the atmosphere when fuel additives are released with diesel fuel combustion.

The zinc oxide nanoparticles may dissolve, or they may remain as a particle, or re-form as a particle, as they are processed through wastewater treatment. At the final stage of wastewater treatment there is a solid material, called biosolids, which is applied to soils in many parts of the U.S. This solid material fertilizes the soil, returning nitrogen and phosphorus that are captured during wastewater treatment. This is also a point at which zinc oxide and cerium oxide can enter the soil.

The scientists noted that the EPA requires pretreatment programs to limit direct industrial metal discharge into publicly owned wastewater treatment plants. However, the research team conveyed that “MNMs –– while measurable in the wastewater treatment plant systems –– are neither monitored nor regulated, have a high affinity for activated sludge bacteria, and thus concentrate in biosolids.”

The authors pointed out that soybean crops are farmed with equipment powered by fossil fuels, and thus MNMs can also be deposited into the soil through exhaust.

The study showed that soybean plants grown in soil that contained zinc oxide bioaccumulated zinc; they absorbed it into the stems, leaves, and beans. Food quality was affected, although it may not be harmful to humans to eat the soybeans if the zinc is in the form of ions or salts, in the plants, according to Holden.

In the case of cerium oxide, the nanoparticles did not bioaccumulate, but plant growth was stunted. Changes occurred in the root nodules, where symbiotic bacteria normally accumulate and convert atmospheric nitrogen into ammonium, which fertilizes the plant. The changes in the root nodules indicate that greater use of synthetic fertilizers might be necessary with the buildup of MNMs in the soil.

At this point, the researchers don’t know how zinc oxide nanoparticles and cerium oxide nanoparticles currently used in consumer products and elsewhere are likely to affect agricultural lands. The only certainty is that these nanoparticles are used in consumer goods and, according to Holden, they are entering agricultural soil.

The citation for the article,

Soybean susceptibility to manufactured nanomaterials with evidence for food quality and soil fertility interruption by John H. Priester, Yuan Ge, Randall E. Mielke, Allison M. Horst Shelly Cole Moritz, Katherine Espinosa, Jeff Gelb, Sharon L. Walker, Roger M. Nisbet, Youn-Joo An, Joshua P. Schimel, Reid G. Palmer, Jose A. Hernandez-Viezcas, Lijuan Zhao, Jorge L. Gardea-Torresdey, Patricia A. Holden. Published online [Proceedings of the National Academy of Sciences {PNAS}] before print August 20, 2012, doi: 10.1073/pnas.1205431109

The article is open access and available here.

 

Nanosilver disinfectant spray: final report from the US Environmental Protection Agency

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The Aug.5, 2012 news item on Nanowerk is an announcement of the final report from the US Environmental Protection Agency’s (EPA) National Center for Environmental Assessment on nanosilver  (nano Ag) disinfectant spray,

This report presents a case study of engineered nanoscale silver (nano-Ag), focusing on the specific example of nano-Ag as possibly used in disinfectant sprays.
This case study is organized around the comprehensive environmental assessment (CEA) framework, which structures available information pertaining to the product life cycle, environmental transport and fate, exposure-dose in receptors (i.e., humans, ecological populations, and the environment), and potential impacts in these receptors. The document does not draw conclusions about potential risks. Instead, it is intended to be used as part of a process to identify what is known and unknown about nano-Ag in a selected application. In turn, the external review draft of the document provided a starting point to identify and prioritize possible research directions to support future assessments of nanomaterials.

The Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray (Final Report) is approximately 423 pages and the comprehensive environmental assessment framework mentioned seems to be an analytical tool used to establish directions for future research. In a July 5, 2012 posting (Toxicology convo heats up: OECD releases report on inhalation toxicity testing and Nature Nanotechnology publishes severe critique of silver toxicity overanalysis) I made note of some comments on inhalation testing and reports about nanosilver toxicity issued by international institutions that seem à propos in this context. (I first wrote about this study in an Aug. 17, 2010 posting when the EPA had released a draft version for comments.)

The relationship of silver ions & nanoparticles, Nietzsche, and Rice University

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My hat’s off to Mike Williams for introducing Nietzsche into a news item about silver nanoparticles and toxicity. Here’s the line from his July 11, 2012 Rice University news release (Note: I have removed some links),

Their work comes with a Nietzsche-esque warning: Use enough. If you don’t kill them, you make them stronger.

Scientists have long known that silver ions, which flow from nanoparticles when oxidized, are deadly to bacteria. Silver nanoparticles are used just about everywhere, including in cosmetics, socks, food containers, detergents, sprays and a wide range of other products to stop the spread of germs.

But scientists have also suspected silver nanoparticles themselves may be toxic to bacteria, particularly the smallest of them at about 3 nanometers. Not so, according to the Rice team that reported its results this month in the American Chemical Society journal Nano Letters.

This next bit describing the research is an example of what I find so compelling (curiosity and persistence) about science,

To figure that out, the researchers had to strip the particles of their powers. “Our original expectation was that the smaller a particle is, the greater the toxicity,” said Zongming Xiu, a Rice postdoctoral researcher and lead author of the paper. Xiu set out to test nanoparticles, both commercially available and custom-synthesized from 3 to 11 nanometers, to see whether there was a correlation between size and toxicity.

“We could not get consistent results,” he said. “It was very frustrating and really weird.”

Here’s what they did next, what they found, and the implications of their findings,

Xiu decided to test nanoparticle toxicity in an anaerobic environment – that is, sealed inside a chamber with no exposure to oxygen — to control the silver ions’ release. He found that the filtered particles were a lot less toxic to microbes than silver ions.

Working with the lab of Rice chemist Vicki Colvin, the team then synthesized silver nanoparticles inside the anaerobic chamber to eliminate any chance of oxidation. “We found the particles, even up to a concentration of 195 parts per million, were still not toxic to bacteria,” Xiu said. “But for the ionic silver, a concentration of about 15 parts per billion would kill all the bacteria present. That told us the particle is 7,665 times less toxic than the silver ions, indicating a negligible toxicity.”

“The point of that experiment,” Alvarez [Pedro Alvarez, George R. Brown Professor and chair of Rice’s Civil and Environmental Engineering Department] said, “was to show that a lot of people were obtaining data that was confounded by a release of ions, which was occurring during exposure they perhaps weren’t aware of.”

Alvarez suggested the team’s anaerobic method may be used to test many other kinds of metallic nanoparticles for toxicity and could help fine-tune the antibacterial qualities of silver particles. In their tests, the Rice researchers also found evidence of homesis; [e.g..,] E. coli became stimulated by silver ions when they encountered doses too small to kill them.

“Ultimately, we want to control the rate of (ion) release to obtain the desired concentrations that just do the job,” Alvarez said. “You don’t want to overshoot and overload the environment with toxic ions while depleting silver, which is a noble metal, a valuable resource – and a somewhat expensive disinfectant. But you don’t want to undershoot, either.”

He said the finding should shift the debate over the size, shape and coating of silver nanoparticles. [emphasis mine] “Of course they matter,” Alvarez said, “but only indirectly, as far as these variables affect the dissolution rate of the ions. The key determinant of toxicity is the silver ions. So the focus should be on mass-transfer processes and controlled-release mechanisms.”

Interestingly, this is a joint US-UK effort (US Environmental Protection Agency and the U.K. Natural Environment Research Council). H/T to Will Soutter’s July 12, 2012 news item on Azonano for the information about this latest silver nanoparticle research from Rice University. The July 11, 2012 news item on Nanowerk also features information about the silver nanoparticles, ions, and Rice University.

I have mentioned Vicki Colvin’s work previously including this Jan. 28, 2011 posting about a UK/US joint environmental research effort. I have also mentioned Pedro Alvarez a few times including this Aug. 2, 2010 posting about nanomaterials and the construction industry.

Nanomaterials and toxicology (US Environmental Protection Agency and National Institute of Occupational Health and Safety)

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It seems to be ‘toxicology and nanomaterials’ season right now. In addition to the ISO (International Standards Organization) technical report on nanomaterials and toxicology which was released in early June (mentioned in my June 4, 2012 posting), the US Environmental Protection Agency (EPA) and the US National Institute of Occupational Safety and Health (NIOSH) have released new reports.

Yesterday (July 2, 2012), the EPA posted a notice on the US Federal Register about a report, a commenting period, and a public information exchange meeting for “Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether Flame-Retardant Coatings Applied to Upholstery Textiles.”

As I noted in an Aug. 27, 2010 posting, the EPA has adopted a very interesting approach to studying possible toxicological effects due to nanomaterials (and other materials),

Such case studies do not represent completed or even preliminary assessments; rather, they are intended as a starting point in a process to identify and prioritize possible research directions to support future assessments of nanomaterials.

Part of the rationale for focusing on a series of nanomaterial case studies is that such materials and applications can have highly varied and complex properties that make considering them in the abstract or in generalities quite difficult. Different materials and different applications of a given material could raise unique questions or issues as well as some issues that are common to various applications of a given nanomaterial or even to different nanomaterials. After several individual case studies have been examined, refining a strategy for nanomaterials research to support long-term assessment efforts should be possible. (p. 19 PDF, p. 1-1 in print version of a  US EPA silver nanomaterials draft report)

The July 3, 2012 news item on Nanowerk offers more detail about this latest case study (Note: I have removed a link),

EPA announces the release of the draft report, Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotube and Decabromodiphenyl Ether Flame-Retardant Coatings Applied to Upholstery Textiles (External Review Draft), for public viewing and comment. This was announced in a July 2, 2012 Federal Register Notice  along with information about the upcoming public Information Exchange Meeting scheduled for October 29, 2012. The purpose of this meeting is to receive comments and questions on the draft document, as well as provide information on the draft document and a workshop process that it will be used in, which is being conducted independently by RTI International, a contractor for EPA. The deadline for comments on the draft document is August 31, 2012. [emphases mine]

The notice on the EPA website offers details and extensive links to satisfy your information needs on this matter,

The draft document is intended to be used as part of a process to identify what is known and, more importantly, what is not yet known that could be of value in assessing the broad implications of specific nanomaterials. Like previous case studies (see History/ Chronology below [on the EPA website]), this draft case study on multiwalled carbon nanotubes (MWCNTs) is based on the comprehensive environmental assessment (CEA) approach, which consists of both a framework and a process. Unlike previous case studies this case study incorporates information about a traditional (i.e., “non-nano-enabled”) product, against which the MWCNT flame-retardant coating applied to upholstery textiles (i.e., the “nano-enabled” product) can be compared. The comparative element serves dual-purposes: 1) to provide a more robust database that facilitates identification of data gaps related to the nano-enabled product and 2) to provide a context for identifying key factors and data gaps for future efforts to evaluate risk-related trade-offs between a nano-enabled and non-nano-enabled product.

This draft case study does not represent a completed or even a preliminary assessment of MWCNTs; rather, it uses the CEA framework to structure information from available literature and other resources (e.g., government reports) on the product life cycle, fate and transport processes in various environmental media, exposure-dose characterization, and impacts in human, ecological, and environmental receptors. Importantly, information on other direct and indirect ramifications of both primary and secondary substances or stressors associated with the nanomaterial is also included when available. The draft case study provides a basis for the next step of the CEA process, whereby collective judgment is used to identify and prioritize research gaps to support future assessment efforts that inform near-term risk management goals.

Meanwhile, NIOSH has released a safety guide (from the June 29, 2012 news item on Nanowerk),

The National Institute for Occupational Safety and Health (NIOSH) has published “General Safe Practices for Working with Engineered Nanomaterials in Research Laboratories” (pdf).
…

With the publication of this document, NIOSH hopes to raise awareness of the occupational safety and health practices that should be followed during the synthesis, characterization, and experimentation with engineered nanomaterials in a laboratory setting. The document contains recommendations on engineering controls and safe practices for handling engineered nanomaterials in laboratories and some pilot scale operations. This guidance was designed to be used in tandem with well-established practices and the laboratory’s chemical hygiene plan. As our knowledge of nanotechnology increases, so too will our efforts to provide additional guidance materials for working safely with engineered nanomaterials.

Here is more information  from the executive summary of the General Safe Practices for Working with Engineered Nanomaterials in Research Laboratories,

Risk Management

Risk management is an integral part of occupational health and safety. Potential expo­sures to nanomaterials can be controlled in research laboratories through a flexible and adaptive risk management program. An effective program provides the framework to anticipate the emergence of this technology into laboratory settings, recognize the po­tential hazards, evaluate the exposure to the nanomaterial, develop controls to prevent or minimize exposure, and confirm the effectiveness of those controls.

Hazard Identification

Experimental animal studies indicate that potentially adverse health effects may result from exposure to nanomaterials. Experimental studies in rodents and cell cultures have shown that the toxicity of ultrafine particles or nanoparticles is greater than the toxicity of the same mass of larger particles of similar chemical composition.

Research demonstrates that inhalation is a significant route of exposure for nanoma­terials. Evidence from animal studies indicates that inhaled nanoparticles may deposit deep in lung tissue, possibly interfering with lung function. It is also theorized that nanoparticles may enter the bloodstream through the lungs and transfer to other or­gans. Dermal exposure and subsequent penetration of nanomaterials may cause local or systemic effects. Ingestion is a third potential route of exposure. Little is known about the possible adverse effects of ingestion of nanomaterials, although some evidence sug­gests that nanosized particles can be transferred across the intestinal wall.

Exposure Assessment

Exposure assessment is a key element of an effective risk management program. The ex­posure assessment should identify tasks that contribute to nanomaterial exposure and the workers conducting those tasks. An inventory of tasks should be developed that in­cludes information on the duration and frequency of tasks that may result in exposure, along with the quantity of the material being handled, dustiness of the nanomaterial, and its physical form. A thorough understanding of the exposure potential will guide exposure assessment measurements, which will help determine the type of controls re­quired for exposure mitigation.

Exposure Control

Exposure control is the use of a set of tools or strategies for decreasing or eliminating worker exposure to a particular agent. Exposure control consists of a standardized hi­erarchy to include (in priority order): elimination, substitution, isolation, engineering controls, administrative controls, or if no other option is available, personal protective equipment (PPE).

Substitution or elimination is not often feasible for workers performing research with nanomaterials; however, it may be possible to change some aspects of the physical form of the nanomaterial or the process in a way that reduces nanomaterial release.

Isolation includes the physical separation and containment of a process or piece of equipment, either by placing it in an area separate from the worker or by putting it within an enclosure that contains any nanomaterials that might be released.

Engineering controls include any physical change to the process that reduces emissions or exposure to the material being contained or controlled. Ventilation is a form of engi­neering control that can be used to reduce occupational exposures to airborne particu­lates. General exhaust ventilation (GEV), also known as dilution ventilation, permits the release of the contaminant into the workplace air and then dilutes the concentration to an acceptable level. GEV alone is not an appropriate control for engineered nano­materials or any other uncharacterized new chemical entity. Local exhaust ventilation (LEV), such as the standard laboratory chemical hood (formerly known as a laboratory fume hood), captures emissions at the source and thereby removes contaminants from the immediate occupational environment. Using selected forms of LEV properly is ap­propriate for control of engineered nanomaterials.

Administrative controls can limit workers’ exposures through techniques such as us­ing job-rotation schedules that reduce the time an individual is exposed to a substance. Administrative controls may consist of standard operating procedures, general or spe­cialized housekeeping procedures, spill prevention and control, and proper labeling and storage of nanomaterials. Employee training on the appropriate use and handling of nanomaterials is also an important administrative function.

PPE creates a barrier between the worker and nanomaterials in order to reduce expo­sures. PPE may include laboratory coats, impervious clothing, closed-toe shoes, long pants, safety glasses, face shields, impervious gloves, and respirators.

Other Considerations

Control verification or confirmation is essential to ensure that the implemented tools or strategies are performing as specified. Control verification can be performed with traditional industrial hygiene sampling methods, including area sampling, personal sampling, and real-time measurements. Control verification may also be achieved by monitoring the performance parameters of the control device to ensure that design and performance criteria are met.

Other important considerations for effective risk management of nanomaterial expo­sure include fire and explosion control. Some studies indicate that nanomaterials may be more prone to explosion and combustion than an equivalent mass concentration of larger particles.

Occupational health surveillance is used to identify possible injuries and illnesses and is recommended as a key element in an effective risk management program. Basic medical screening is prudent and should be conducted under the oversight of a qualified health-care professional. (pp. 9 – 11 PDF or pp. vii – ix in print)

The guidance as per the executive summary seems to rely heavily on what I imagine are industrial hygiene practices that should be followed whether or not laboratories are researching nanomaterials.

Two (Denmark & US) contrasting documents about nanomaterials and risk

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The Danes released their NanoRiskCat (NRC) document in early December 2011 while the US National Research Council released its report on the US research strategy on environmental and health impact of engineered nanomaterials today, Jan. 25, 2012.

(BTW, There”s going to be an alphabet soup situation in this posting with two different NRCs [the catalogue] and the US National Research Council for starters. I’ll do my best to keep these entities distinct from each other.)

The documents represent an interesting contrast regarding approaches to nanomaterials and their risks. From the Jan. 25, 2012 Nanowerk Spotlight article about Denmark’s NanoRiskCat,

The project’s aim was to identify, categorize and rank the possible exposure and hazards associated with a nanomaterial in a product. NanoRiskCat is using a stepwise approach based on existing data on the conventional form of the chemical as well as the data that may exist on the nanoform. However, the tool still needs to be further validated and tested on a series of various nano products in order to adjust and optimize the concept and thereby to achieve a screening tool as informative and practical as possible.

Meanwhile, here’s the description of the US NRC’s latest report, from the Jan. 25, 2012 news item on Nanowerk,

Despite extensive investment in nanotechnology and increasing commercialization over the last decade, insufficient understanding remains about the environmental, health, and safety aspects of nanomaterials. Without a coordinated research plan to help guide efforts to manage and avoid potential risks, the future of safe and sustainable nanotechnology is uncertain, says a new report (“A Research Strategy for Environmental, Health, and Safety Aspects of Engineered Nanomaterials“)from the National Research Council. The report presents a strategic approach for developing research and a scientific infrastructure needed to address potential health and environmental risks of nanomaterials. Its effective implementation would require sufficient management and budgetary authority to direct research across federal agencies.

I find it interesting that the US government which has poured billions into its National Nanotechnology Initiative (NNI) is still trying to develop a research strategy for environmental and health impacts while the Danish (who have likely spent far less and, to be fair, likely have less bureaucracy) have created an assessment tool designed to evaluate the exposure to and hazards posed by nanomaterials found in consumer and industrial use.

One other interesting tidbit, both the Danish and the US Environmental Protection Agencies (EPAs) were instigators of their country’s respective documents. The Danish EPA was one of the three funders (the other two were the Danish Technical University and the National Research Centre for the Working Environment) for their NanoRiskCat. The US EPA was one of the sponsors  for the strategy report. The other sponsors include the The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council.

I have to admit I’m getting a little tired of strategy documents and I’m please to see an attempt to evaluate the situation. I’m not sure which version (alpha or beta) of the tool they’ve released but there’s definitely some tweaking to be done as the Danes themselves admit,

It is the view of the Danish EPA that the traffic light ranking [I’m assuming they assign a colour [red, amber, yellow] as a means of quickly identifying a risk level in their documentation of specific nanomaterials) of the health effects may be further modified to obtain a better ranking in the various categories. Thus titanium dioxide in sunscreen is ranked as red due to lung effects of titanium dioxide, because the tool in its present form does not sufficiently take account of which type of health effects that are most relevant for the most relevant exposure route of the product. In this case the inhalational exposure of titanium dioxide from a sun screen seems less relevant.

Yes, I agree that exposure to nanoscale titanium dioxide via inhalation is an unlikely when you’re using a nanosunscreen. Although given some folks I’ve known, it’s not entirely out of the question. (It’s been my experience that people will inhale anything if they think they can get high from it.)

US Environmental Protection Agency needs to do more about possible nanomaterial risks

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The US Environmental Protection Agency (EPA) has its own watchdog, the EPA Office of Inspector General. According to a Jan. 5, 2012 news item on Nanowerk that watchdog has published a report suggesting the EPA should do more to manage nanomaterials risks,

EPA has the statutory authority to regulate nanomaterials but currently lacks the environmental and human health exposure and toxicological data to do so effectively. The Agency proposed a policy under the Federal Insecticide, Fungicide, and Rodenticide Act [FIFRA] to identify new pesticides being registered with nanoscale materials. After minimal industry participation in a voluntary data collection program, the Agency has proposed mandatory reporting rules for nanomaterials under the Federal Insecticide, Fungicide, and Rodenticide Act, and is also developing proposed rules under the Toxic Substances Control Act [TSCA]. However, even if mandatory reporting rules are approved, the effectiveness of EPA’s management of nanomaterials remains in question for a number of reasons:

  • Program offices do not have a formal process to coordinate the dissemination and utilization of the potentially mandated information.
  • EPA is not communicating an overall message to external stakeholders regarding policy changes and the risks of nanomaterials.
  • EPA proposes to regulate nanomaterials as chemicals and its success in managing nanomaterials will be linked to the existing limitations of those applicable statutes.
  • EPA’s management of nanomaterials is limited by lack of risk information and reliance on industry-submitted data.

The full report is titled EPA Needs to Manage Nanomaterial Risks More Effectively, Report No. 12-P-0162.