Tag Archives: toxicity

The Swiss come to a better understanding of nanomaterials

Just to keep things interesting, after the report suggesting most of the information that the OECD (Organization for Economic Cooperation and Development) has on nanomaterials is of little value for determining risk (see my April 5, 2017 posting for more) the Swiss government has released a report where they claim an improved understanding of nanomaterials than they previously had due to further research into the matter. From an April 6, 2017 news item on Nanowerk,

In the past six years, the [Swiss] National Research Programme “Opportunities and Risks of Nanomaterials” (NRP 64) intensively studied the development, use, behaviour and degradation of engineered nanomaterials, including their impact on humans and on the environment.

Twenty-three research projects on biomedicine, the environment, energy, construction materials and food demonstrated the enormous potential of engineered nanoparticles for numerous applications in industry and medicine. Thanks to these projects we now know a great deal more about the risks associated with nanomaterials and are therefore able to more accurately determine where and how they can be safely used.

An April 6, 2017 Swiss National Science Foundation press release, which originated the news item, expands on the theme,

“One of the specified criteria in the programme was that every project had to examine both the opportunities and the risks, and in some cases this was a major challenge for the researchers,” explains Peter Gehr, President of the NRP 64 Steering Committee.

One development that is nearing industrial application concerns a building material strengthened with nanocellulose that can be used to produce a strong but lightweight insulation material. Successful research was also carried out in the area of energy, where the aim was to find a way to make lithium-ion batteries safer and more efficient.

Promising outlook for nanomedicine

A great deal of potential is predicted for the field of nanomedicine. Nine of the 23 projects in NRP 64 focused on biomedical applications of nanoparticles. These include their use for drug delivery, for example in the fight against viruses, or as immune modulators in a vaccine against asthma. Another promising application concerns the use of nanomagnets for filtering out harmful metallic substances from the blood. One of the projects demonstrated that certain nanoparticles can penetrate the placenta barrier, which points to potential new therapy options. The potential of cartilage and bone substitute materials based on nanocellulose or nanofibres was also studied.

The examination of potential health risks was the focus of NRP 64. A number of projects examined what happens when nanoparticles are inhaled, while two focused on ingestion. One of these investigated whether the human gut is able to absorb iron more efficiently if it is administered in the form of iron nanoparticles in a food additive, while the other studied silicon nanoparticles as they occur in powdered condiments. It was ascertained that further studies will be required in order to determine the doses that can be used without risking an inflammatory reaction in the gut.

What happens to engineered nanomaterials in the environment?

The aim of the seven projects focusing on environmental impact was to gain a better understanding of the toxicity of nanomaterials and their degradability, stability and accumulation in the environment and in biological systems. Here, the research teams monitored how engineered nanoparticles disseminate along their lifecycle, and where they end up or how they can be discarded.

One of the projects established that 95 per cent of silver nanoparticles that are washed out of textiles are collected in sewage treatment plants, while the remaining particles end up in sewage sludge, which in Switzerland is incinerated. In another project a measurement device was developed to determine how aquatic microorganisms react when they come into contact with nanoparticles.

Applying results and making them available to industry

“The findings of the NRP 64 projects form the basis for a safe application of nanomaterials,” says Christoph Studer from the Federal Office of Public Health. “It has become apparent that regulatory instruments such as testing guidelines will have to be adapted at both national and international level.” Studer has been closely monitoring the research programme in his capacity as the Swiss government’s representative in NRP 64. In this context, the precautionary matrix developed by the government is an important instrument by means of which companies can systematically assess the risks associated with the use of nanomaterials in their production processes.

The importance of standardised characterisation and evaluation of engineered nanomaterials was highlighted by the close cooperation among researchers in the programme. “The research network that was built up in the framework of NRP 64 is functioning smoothly and needs to be further nurtured,” says Professor Bernd Nowack from Empa, who headed one of the 23 projects.

The results of NRP 64 show that new key technologies such as the use of nanomaterials need to be closely monitored through basic research due to the lack of data on its long-term effects. As Peter Gehr points out, “We now know a lot more about the risks of nanomaterials and how to keep them under control. However, we need to conduct additional research to learn what happens when humans and the environment are exposed to engineered nanoparticles over longer periods, or what happens a long time after a one-off exposure.”

You can find out more about the Opportunities and Risks of Nanomaterials; National Research Programme (NRP 64) here.

The volatile lithium-ion battery

On the heels of Samsung’s Galaxy Note 7 recall due to fires (see Alex Fitzpatrick’s Sept. 9, 2016 article for Time magazine for a good description of lithium-ion batteries and why they catch fire; see my May 29, 2013 posting on lithium-ion batteries, fires [including the airplane fires], and nanotechnology risk assessments), there’s new research on lithium-ion batteries and fires from China. From an Oct. 21, 2016 news item on Nanotechnology Now,

Dozens of dangerous gases are produced by the batteries found in billions of consumer devices, like smartphones and tablets, according to a new study. The research, published in Nano Energy, identified more than 100 toxic gases released by lithium batteries, including carbon monoxide.

An Oct. 20, 2016 Elsevier Publishing press release (also on EurekAlert), which originated the news item, expands on the theme,

The gases are potentially fatal, they can cause strong irritations to the skin, eyes and nasal passages, and harm the wider environment. The researchers behind the study, from the Institute of NBC Defence and Tsinghua University in China, say many people may be unaware of the dangers of overheating, damaging or using a disreputable charger for their rechargeable devices.

In the new study, the researchers investigated a type of rechargeable battery, known as a “lithium-ion” battery, which is placed in two billion consumer devices every year.

“Nowadays, lithium-ion batteries are being actively promoted by many governments all over the world as a viable energy solution to power everything from electric vehicles to mobile devices. The lithium-ion battery is used by millions of families, so it is imperative that the general public understand the risks behind this energy source,” explained Dr. Jie Sun, lead author and professor at the Institute of NBC Defence.

The dangers of exploding batteries have led manufacturers to recall millions of devices: Dell recalled four million laptops in 2006 and millions of Samsung Galaxy Note 7 devices were recalled this month after reports of battery fires. But the threats posed by toxic gas emissions and the source of these emissions are not well understood.

Dr. Sun and her colleagues identified several factors that can cause an increase in the concentration of the toxic gases emitted. A fully charged battery will release more toxic gases than a battery with 50 percent charge, for example. The chemicals contained in the batteries and their capacity to release charge also affected the concentrations and types of toxic gases released.

Identifying the gases produced and the reasons for their emission gives manufacturers a better understanding of how to reduce toxic emissions and protect the wider public, as lithium-ion batteries are used in a wide range of environments.

“Such dangerous substances, in particular carbon monoxide, have the potential to cause serious harm within a short period of time if they leak inside a small, sealed environment, such as the interior of a car or an airplane compartment,” Dr. Sun said.

Almost 20,000 lithium-ion batteries were heated to the point of combustion in the study, causing most devices to explode and all to emit a range of toxic gases. Batteries can be exposed to such temperature extremes in the real world, for example, if the battery overheats or is damaged in some way.

The researchers now plan to develop this detection technique to improve the safety of lithium-ion batteries so they can be used to power the electric vehicles of the future safely.

“We hope this research will allow the lithium-ion battery industry and electric vehicle sector to continue to expand and develop with a greater understanding of the potential hazards and ways to combat these issues,” Sun concluded.

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

Toxicity, a serious concern of thermal runaway from commercial Li-ion battery by Jie Sun, Jigang Li, Tian Zhou, Kai Yang, Shouping Wei, Na Tang, Nannan Dang, Hong Li, Xinping Qiu, Liquan Chend. Nano Energy Volume 27, September 2016, Pages 313–319  http://dx.doi.org/10.1016/j.nanoen.2016.06.031

This paper appears to be open access.

Study nanomaterial toxicity without testing animals

The process of moving on from testing on animals is laborious as new techniques are pioneered and, perhaps more arduously, people’s opinions and habits are changed. The People for the Ethical Treatment of Animals (PETA) organization focusing the research end of things has announced a means of predicting carbon nanotube toxicity in lungs according to an April 25, 2016 news item on Nanowerk (Note: A link has been removed),

A workshop organized last year [2015] by the PETA International Science Consortium Ltd has resulted in an article published today in the journal Particle and Fibre Toxicology (“Aerosol generation and characterization of multi-walled carbon nanotubes [MWCNTs] exposed to cells cultured at the air-liquid interface”). It describes aerosol generation and exposure tools that can be used to predict toxicity in human lungs following inhalation of nanomaterials.

An April 25, 2016 PETA press release on EurekAlert, which originated the news item, explains further without much more detail,

Nanomaterials are increasingly being used in consumer products such as paints, construction materials, and food packaging, making human exposure to these materials more likely. One of the common ways humans may be exposed to these substances is by inhalation, therefore, regulatory agencies often require the toxicity of these materials on the lungs to be tested. These tests usually involve confining rats to small tubes the size of their bodies and forcing them to breathe potentially toxic substances before they are killed. However, time, cost, scientific and ethical issues have led scientists to develop methods that do not use animals. The tools described in the new article are used to deposit nanomaterials (or other inhalable substances) onto human lung cells grown in a petri dish.

Co-authors of the Particle and Fibre Toxicology article are scientists from the PETA Science Consortium , The Dow Chemical Company, Baylor University, and the U.S. NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM).

“Promoting non-animal methods to assess nanotoxicity has been a focus of the PETA International Science Consortium”, said Dr. Monita Sharma, co-author of the publication and Nanotechnology Specialist at the Consortium, “we organized an international workshop last year on inhalation testing of nanomaterials and this review describes some of the tools that can be used to provide a better understanding of what happens in humans after inhaling these substances.” During the workshop, experts provided recommendations on the design of an in vitro test to assess the toxicity of nanomaterials (especially multi-walled carbon nanotubes) in the lung, including cell types, endpoints, exposure systems, and dosimetry considerations. Additional publications summarizing the outcomes of the workshop are forthcoming.

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

Aerosol generation and characterization of multi-walled carbon nanotubes exposed to cells cultured at the air-liquid interface by William W. Polk, Monita Sharma, Christie M. Sayes, Jon A. Hotchkiss, and Amy J. Clippinger. Particle and Fibre Toxicology201613:20 DOI: 10.1186/s12989-016-0131-y Published: 23 April 2016

This is an open access paper.

Research into nanosilver’s antibiotic properties and nanogold’s detection skills

There is a puzzling and exciting announcement from the Canadian Light Source in a May 27, 2015 news item on Nanowerk,

Precious metals like silver and gold have biomedical properties that have been used for centuries, but how do these materials effectively combat the likes of cancer and bacteria without contaminating the patient and the environment?

These are the questions that researchers from Dalhousie University and the Canadian Light Source are trying to find out.

Perhaps I’m misreading the announcement but the statement that nanosilver and nanogold don’t contaminate the patient or the environment is a bit exuberant. There are published studies examining questions about whether or not nanosilver may affect the environment and health and the answer is that no one is certain yet. You can read more about two studies highlighted in my February 28, 2013 posting titled:  Silver nanoparticles, water, the environment, and toxicity. As for nanosilver and nanogold not contaminating patients, that too is a problematic statement. For example, I have this paper which cites several studies on nanogold and possible toxicity. The paper itself is a plea to standardize testing and protocols so researchers can do a better job of establishing toxicity issues with nanogold.


Reservations aside, it’s good to learn of some Canadian research in this area. From a May 26, 2015 Canadian Light Source news release, which originated the news item, provides more details about the research and its current focus on nanosilver,

“Gold and silver are both exciting materials,” said Peng Zhang, Associate Professor of Chemistry at Dalhousie. “We can use gold to either detect or kill cancer cells. Silver is also excited and a very promising material as an antibacterial agents.”

Zhang said that if you compare silver to current antibiotics, silver does not show drug-resistant behaviour. “But with silver, so far, we are not finding that,” he added.

Finding out why silver is such a great antibacterial agent is the focus of Zhang’s research, recently published in the journal Langmuir.

“We want to understand the relationship between the atomic structure and bioactivity of nanosilver as to why it is so efficient at inhibiting bacterial activity. It’s a big puzzle.”

Zhang said it is very hard to understand what is happening at the atomic level. Using small nanosilver particles is the most effective way, because when you make silver small, you can expect higher activity because of the increased surface area.

This poses another problem however, as the nanosilver needs to be stabilized with a coating or the silver particles will bond together forming large pieces of silver that do not efficiently interact with the bacteria.

Zhang’s group used two different coatings to compare the effectiveness of the silver as an antibacterial agent. The first was a small amino acid coating and the other was a larger polymer coating. And after testing the interactions between the nanosilver and the bacteria, and looking at the atomic structure of nanosilver using the CLS and the Advanced Photon Source, the researchers were surprised to find that the thicker, larger polymer coating actually created a better delivery method for sliver to inhibit the bacteria.

“We proposed that the small amino acid coating would bind so tightly to the silver surface that it would be difficult for  the silver atoms to interact with the bacteria, whereas the polymers are actually very good at staying in place and still releasing sufficient amount of silver with the bacteria.”

Zhang said the next steps will be to find out if the nanosilver is actually attacking good cells in living systems before they can make any further progress on determining whether nanosilver is an effective and efficient antibactieral agent that could be used to cure human and animal diseases.

Here’s an illustration provided by the researchers,

The atomic structure of nanosilver, revealed by synchrotron X-ray spectroscopy, is proving to be a determinant of silver’s antibacterial activity. Padmos, J. Daniel, et al. "Impact of Protecting Ligands on Surface Structure and Antibacterial Activity of Silver Nanoparticles." Langmuir 31.12 (2015): 3745-3752.

The atomic structure of nanosilver, revealed by synchrotron X-ray spectroscopy, is proving to be a determinant of silver’s antibacterial activity.
Padmos, J. Daniel, et al. “Impact of Protecting Ligands on Surface Structure and Antibacterial Activity of Silver Nanoparticles.” Langmuir 31.12 (2015): 3745-3752.

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

Impact of Protecting Ligands on Surface Structure and Antibacterial Activity of Silver Nanoparticles by J. Daniel Padmos, Robert T. M. Boudreau, Donald F. Weaver, and Peng Zhang. Langmuir, 2015, 31 (12), pp 3745–3752
DOI: 10.1021/acs.langmuir.5b00049 Publication Date (Web): March 15, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Copper nanoparticles, toxicity research, colons, zebrafish, and septic tanks

Alicia Taylor, a graduate student at UC Riverside, surrounded by buckets of effluent from the septic tank system she used for her research. Courtesy: University of California at Riverside

Alicia Taylor, a graduate student at UC Riverside, surrounded by buckets of effluent from the septic tank system she used for her research. Courtesy: University of California at Riverside

Those buckets of efflluent are strangely compelling. I think it’s the abundance of orange. More seriously, a March 2, 2015 news item on Nanowerk poses a question about copper nanoparticles,

What do a human colon, septic tank, copper nanoparticles and zebrafish have in common?

They were the key components used by researchers at the University of California, Riverside and UCLA [University of California at Los Angeles] to study the impact copper nanoparticles, which are found in everything from paint to cosmetics, have on organisms inadvertently exposed to them.

The researchers found that the copper nanoparticles, when studied outside the septic tank, impacted zebrafish embryo hatching rates at concentrations as low as 0.5 parts per million. However, when the copper nanoparticles were released into the replica septic tank, which included liquids that simulated human digested food and household wastewater, they were not bioavailable and didn’t impact hatching rates.

A March 2, 2015 University of California at Riverside (UCR) news release (also on EurekAlert), which originated the news item, provides more detail about the research,

“The results are encouraging because they show with a properly functioning septic tank we can eliminate the toxicity of these nanoparticles,” said Alicia Taylor, a graduate student working in the lab of Sharon Walker, a professor of chemical and environmental engineering at the University of California, Riverside’s Bourns College of Engineering.

The research comes at a time when products with nanoparticles are increasingly entering the marketplace. While the safety of workers and consumers exposed to nanoparticles has been studied, much less is known about the environmental implications of nanoparticles. The Environmental Protection Agency is currently accessing the possible effects of nanomaterials, including those made of copper, have on human health and ecosystem health.

The UC Riverside and UCLA [University of California at Los Angeles] researchers dosed the septic tank with micro copper and nano copper, which are elemental forms of copper but encompass different sizes and uses in products, and CuPRO, a nano copper-based material used as an antifungal agent to spray agricultural crops and lawns.

While these copper-based materials have beneficial purposes, inadvertent exposure to organisms such as fish or fish embryos has not received sufficient attention because it is difficult to model complicated exposure environments.

The UC Riverside researchers solved that problem by creating a unique experimental system that consists of the replica human colon and a replica two-compartment septic tank, which was originally an acyclic septic tank. The model colon is made of a custom-built 20-inch-long glass tube with a 2-inch diameter with a rubber stopper at both ends and a tube-shaped membrane typically used for dialysis treatments within the glass tube.

To simulate human feeding, 100 milliliters of a 20-ingredient mixture that replicated digested food was pumped into the dialysis tube at 9 a.m., 3 p.m. and 9 p.m. for five-day-long experiments over nine months.

The septic tank was filled with waste from the colon along with synthetic greywater, which is meant to simulate wastewater from sources such as sinks and bathtubs, and the copper nanoparticles. The researchers built a septic tank because 20 to 30 percent of American households rely on them for sewage treatment. Moreover, research has shown up to 40 percent of septic tanks don’t function properly. This is a concern if the copper materials are disrupting the function of the septic system, which would lead to untreated waste entering the soil and groundwater.

Once the primary chamber of the septic system was full, liquid began to enter the second chamber. Once a week, the effluent was drained from the secondary chamber and it was placed into sealed five-gallon containers. The effluent was then used in combination with zebrafish embryos in a high content screening process using multiwall plates to access hatching rates.

The remaining effluent has been saved and sits in 30 five-gallon buckets in a closet at UC Riverside because some collaborators have requested samples of the liquid for their experiments.

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

Understanding the Transformation, Speciation, and Hazard Potential of Copper Particles in a Model Septic Tank System Using Zebrafish to Monitor the Effluent* by Sijie Lin, Alicia A. Taylor, Zhaoxia Ji, Chong Hyun Chang, Nichola M. Kinsinger, William Ueng, Sharon L. Walker, and André E. Nel. ACS Nano, 2015, 9 (2), pp 2038–2048 DOI: 10.1021/nn507216f
Publication Date (Web): January 27, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

* Link added March 10, 2015.

Glove sensors and toxic substances

Gloves that change colour as a signal you’re handling toxic substances have been developed by a research team at  the Fraunhofer Institute according to a May 2, 2013 Fraunhofer Research Institution for Modular Solid State Technologies EMFT news release (also on EurekAlert as a re-issued June 7, 2013 news release),

Employees in chemical production, the semiconductor industry or in laboratories are frequently exposed to harmful substances. The problem: Many of these aggressive substances are imperceptible to human senses, which makes handling them so risky. That’s why there is a broad range of solutions that employers can use to protect their staff from hazardous substances – from highly sensitive measuring equipment to heat imaging cameras. Soon, this spectrum will be enhanced by one more clever solution that is easy to handle, and that dispenses with a power supply. Researchers at the Fraunhofer Research Institution for Modular Solid State Technologies EMFT in Regensburg have engineered a glove that recognizes if toxic substances are present in the surrounding air.

Here’s an image of the glove,

The sensor glove turns blue in the presence of hazardous substances. (© Fraunhofer EMFT)

The sensor glove turns blue in the presence of hazardous substances. (© Fraunhofer EMFT)

The news release provides more details,

The protective glove is equipped with custom-made sensor materials and indicates the presence of toxic substances by changing colors. In this regard, the scientists adapted the materials to the corresponding analytes, and thus, the application. The color change – from colorless (no toxic substance) to blue (toxic substance detected), for example – warns the employee immediately. …


The warning signal is triggered by an indicator dye integrated into the glove that reacts to the presence of analytes, in this case, the toxic substances. The experts at EMFT used a variety of techniques in order to furnish textiles with sensor-activated dyes. The sensor-activated dyes are applied to the clothing with the customary dye and print process, for example, by affixing them in an immersion bath. Previously, the researchers used targeted chemical modification to adapt the color molecules to the fiber properties of the respective textile. Alternatively, the textiles can also be coated with sensor particles that are furnished with sensor dyes. For this purpose, the scientists integrated the dye molecules either into commercial pigments or they built them up on an entirely synthetic basis. The pigments are then manufactured according to the customary textile finishing process, for instance, the sensor particles are also suitable for silkscreening. “Which version we opt for depends on the requirements of the planned application,” says Trupp [Dr. Sabine Trupp, head of the Fraunhofer EMFT Sensor Materials group].

The challenge lies foremost in the tailored development of sensor dyes. “The dye molecule must detect a specific analyte in a targeted manner – only then will a chemical reaction occur. Moreover, the dye must adhere securely; it cannot disappear due to washing. We aim for the customer’s preferences in the color selection as well. All of these aspects must be kept in mind when developing the molecule and pigment properties,” explains Trupp.

The technology could be extended to do more and could be adapted for other applications (from the news release),

The expert already has new ideas about how the solution could be developed further. For example, a miniaturized sensor module, integrated into textiles, could record toxic substances, store the measurement data and even transmit them to a main unit. This way, you could document how frequently an individual within a hazardous environment was exposed to poisonous concentrations over a longer period of time.

The researchers also envision other potential applications in the foodstuffs industry: In the future, color indicator systems integrated into foils or bottle closures are intended to make the quality status of the packaged foods visible. Because the sell-by date does not represent a guarantee of any kind. Foodstuffs may often spoil prematurely – unnoticed by the consumer – due to a packaging error, or in the warehousing, or due to disruptions in the refrigeration chain. Oil-based and fat-containing products are specifically prone to this, as are meats, fish and ready meals.

The notion that food packaging could be designed to include sensors that alert consumers and retailers about product spoilage is not new and was mentioned recently and briefly in my Mar. 25, 2013 posting which featured excerpts from an interview with biotechnologist Christoph Meili about nanotechnology-enabled food packaging.

NanoSustain published four case studies: zinc oxide, titanium dioxide, carbon nanotubes, and nanocellulose

A May 17, 2013 news item on Nanowerk highlight a European Commission-funded project, NanoSustain and its publication of a fact sheet and four case studies,,

NanoSustain, a €2.5 million NMP small collaborative project (2010-2013) funded by the European Union under FP7, has published a fact sheet and four case studies addressing these issues.

How do nanotechnology-based products impact human health and the environment?
Can they be recycled?
Can they be safely disposed of?
How can you find out?

The March 20, 2013 NanoSustain news release, which originated the news item, goes on to explain,

… the EC-funded NanoSustain project has been developing new sustainable solutions through an investigation of the life-cycle of nanotechnology-based products, in particular the physical and chemical characteristics of materials, hazard and exposure aspects, and end-of-life disposal or recycling to determine the fate and impact of nanomaterials.

A summary of the different materials and products tested within NanoSustain:

• Case Study #1: Titanium dioxide for paints
• Case Study #2: Zinc oxide for glazing products
• Case Study #3: Carbon nanotubes epoxy resins for plastics
– for structural or electrical/antistatic applications
• Case Study #4: Nanocellulose for advanced paper applications

Information about the individual experimental approaches

Descriptions of the different techniques developed

How these techniques have been successfully applied in physical-chemical characterisation; life-cycle analysis; final disposal; recycling.

Getting access to the case case studies and the fact sheet requires filling out a form but once you’ve done that you get instant access to the materials.

Here’s some information from EuroSustain’s fact sheet,


Analytical Techniques

Development of sustainable solutions for nanotechnology-based products based on hazard characterization and LCA1 The primary goal of the NanoSustain project is to develop new technical solutions for the sustainable design and use, recycling and final treatment of selected nanotechnology-based products.

To achieve this the project has the following objectives: 1) to assess the hazard of selected nanomaterials based on a comprehensive data survey and generation concerning their physicochemical (PC) and toxicological properties, exposure probabilities, etc., and the adaptation, evaluation, validation and use of existing analytical, testing and life-cycle assessment (LCA) methods; 2) to assess the impact of selected products during their life cycle in relation to material and energy flows (LCA); 3) to assess possible exposure routes and risks associated with the handling of these materials, their transformation and final fate; and 4) to explore the feasibility and sustainability of new technical solutions for end-of=life processes, such as reuse/recycling, final treatment or disposal.

Within NanoSustain an assessment has been made of the PC properties, exposure and toxicity, energy and material inputs and outputs at relevant stages of a material or product’s life-cycle. This means: material production, processing, manufacturing, use, transportation, and end-of-life (recycling/disposal). At each stage potential risks to human health and the environment have also been assessed, through a number of experimental models and test systems using materials that would be expected to be released from products containing nanomaterials.

Four nanomaterials were investigated that either already feature in commercial products or are expected to be commercialized on a large scale: titanium dioxide (TiO2) in paint, zinc oxide (ZnO) as a coating for glass, multi-walled carbon nanotubes (MWCNT) in epoxy resins, and nanocellulose in paper.

Detailed information on the nanomaterials have been summarized in internal project material datasheets (MDS), and will be made available as part of peer-reviewed publications on release studies and toxicological investigations. [emphases mine]

Having looked at the four case studies, each of which is two pages, I would describe them as teasers. There’s not a lot of information in them as to the results of the testing which makes sense when you see that they will be publishing in various publications.

I find the inclusion of titanium dioxide, zinc oxide and carbon nanotubes for life-cycle assessments easily understandable as they  have been integrated into many consumer products. However, it’s my understanding that nanocellulose has not reached that level of product integration. Still, given the number of times I’ve been told this is a ‘safe’ product, it’s interesting to see what NanoSustain has to say about its toxicity (from the NanoSustain’s nanocellulose case study),

Work in NanoSustain has provided new data and information on the physicochemical properties, potential human and environmental hazard and risk associated with relevant stages of the life-cycle of nanocellulose based products as well as on the overall energy and material input/output that may happen during manufacturing, use and disposal. Initial results indicate that the nanocellulose degrades efficiently under standard composting conditions, but does not in aquatic environments. Furthermore nanocellulose does not demonstrate any ecotoxicity. Unfortunately nanocellulose forms a gel when suspended in media for inhalation studies, and so no toxicology experiments could be performed (as for the other engineered nanomaterials studied in NanoSustain). Final results will be made available once published in peer-reviewed journals.

I have written many times about nanocellulose, a topic featuring some interesting and confusing nomenclature and taking this opportunity to highlight a couple of responses from folks who took the time to clarify things for me (from my Aug. 2, 2012 posting),

KarenS says:

Hi Maryse!

From my understanding, nanocrystaline cellulose (NCC), cellulose nanocrystals (CNC), cellulose whiskers (CW) and cellulose nanowhiskers (CNW) are all the same stuff: cylindrical rods of crystalline cellulose (diameter: 5-10 nm; length: 20-1000 nm). Cellulose nanofibers or nanofibrils (CNF), on the contrary, are less crystalline and are in the form of long fibers (diameter: 20-50 nm; length: up to several micrometers).

There is still a lot of confusion on the nomenclature of cellulose nanoparticles, but nice explanations (and pictures!) are given here (and also in other papers from the same conference):


and there’s this from my Sept. 26, 2012 posting,

Gary Chinga Carrasco says:

The definition of cellulose nanofibrils as “diameter: 20-50 nm; length: up to several micrometers)” is somewhat simplified. For terminology on MFC terms you may want to take a look at: http://www.nanoscalereslett.com/content/6/1/417

Bringing this piece back to where I started, I look forward to seeing the NanoSustain case studies published with more details in the future.

Note: Since the folks at NanoSustain are likely using their form to collect data, I’m not linking back to the factsheet or nanocellulose case study as I would usually. So, if you want to look at the material, you do need to register via the form.

Beginner’s guide to carbon nanotubes and nanowires

There’s a very nice Apr. 11, 2013  introductory article by David L. Chandler for the Massachusetts Institute of Technology (MIT) news office) about carbon and other nanotubes and nanowires,

The initial discovery of carbon nanotubes — tiny tubes of pure carbon, essentially sheets of graphene rolled up unto a cylinder — is generally credited to a paper published in 1991 by the Japanese physicist Sumio Ijima (although some forms of carbon nanotubes had been observed earlier). Almost immediately, there was an explosion of interest in this exotic form of a commonplace material. Nanowires — solid crystalline fibers, rather than hollow tubes — gained similar prominence a few years later.

Due to their extreme slenderness, both nanotubes and nanowires are essentially one-dimensional. “They are quasi-one-dimensional materials,” says MIT associate professor of materials science and engineering Silvija Gradečak: “Two of their dimensions are on the nanometer scale.” This one-dimensionality confers distinctive electrical and optical properties.

For one thing, it means that the electrons and photons within these nanowires experience “quantum confinement effects,” Gradečak says. And yet, unlike other materials that produce such quantum effects, such as quantum dots, nanowires’ length makes it possible for them to connect with other macroscopic devices and the outside world.

The structure of a nanowire is so simple that there’s no room for defects, and electrons pass through unimpeded, Gradečak explains. This sidesteps a major problem with typical crystalline semiconductors, such as those made from a wafer of silicon: There are always defects in those structures, and those defects interfere with the passage of electrons.

H/T Nanowerk Apr. 11, 2013 news item. There’s more to read at the MIT website and I recommend this as a good beginner’s piece since the focus is entirely on what carbon nanotubes and nanowires are , how they are formed, and which distinctive properties are theirs. You can find some of this information in the odd paragraph of a news release touting the latest research but I’m very excited to find this much explanatory material in one place.

Another very good explanatory piece, this one focused on carbon nanotubes and risk, is a video produced by Dr. Andrew Maynard for his Risk Bites series. I featured and embedded it in my Mar. 15, 2013 posting. titled, The long, the short, the straight, and the curved of them: all about carbon nanotubes.  You can also find the video in Andrew’s Mar. 14, 2013 posting on his 2020 Science blog where he also writes about the then recently released information from the US National Institute of Occupational Health and Safety on carbon nanotubes and toxicity.

Looking blue? Maybe it’s silver nanoparticles

Looking blue can mean feeling sad or it can indicate that you have argyria, a condition caused by ingesting too much silver. An Oct. 29, 2012 news item on Nanowerk about research on argyria taking place at Brown University reveals the latest insight on the cause for this condition,

Researchers from Brown University have shown for the first time how ingesting too much silver can cause argyria, a rare condition in which patients’ skin turns a striking shade of grayish blue.

“It’s the first conceptual model giving the whole picture of how one develops this condition,” said Robert Hurt, professor of engineering at Brown and part of the research team. “What’s interesting here is that the particles someone ingests aren’t the particles that ultimately cause the disorder.”

Scientists have known for years argyria had something to do with silver. The condition has been documented in people who (ill advisedly) drink antimicrobial health tonics containing silver nanoparticles and in people who have had extensive medical treatments involving silver. Tissue samples from patients showed silver particles actually lodged deep in the skin, but it wasn’t clear how they got there.

As it turns out, argyria is caused by a complex series of chemical reactions, Hurt said. His paper on the subject, authored with Brown colleagues Jingyu Liu, Zhongying Wang, Frances Liu, and Agnes Kane, is published in the journal ACS Nano (“Chemical Transformations of Nanosilver in Biological Environments” [behind a paywall]).

The Oct. 25, 2012 Brown University news release (which originated the news item) provides more detail,

Hurt and his team have been studying the environmental impact of silver, specifically silver nanoparticles, for years. They’ve found that nanosilver tends to corrode in acidic environments, giving off charged ions — silver salts — that can be toxic in large amounts. Hurt’s graduate student, Jingyu Liu (now a postdoctoral fellow at the National Institute of Standards and Technology), thought those same toxic ions might also be produced when silver enters the body, and could play a role in argyria.

To find out, the researchers mixed a series chemical treatments that could simulate what might happen to silver inside the body. One treatment simulated the acidic environment in the gastrointestinal tract; one mimicked the protein content of the bloodstream; and a collagen gel replicated the base membranes of the skin.

They found that nanosilver corrodes in stomach acid in much the same way it does in other acidic environments. Corrosion strips silver atoms of electrons, forming positively charged silver salt ions. Those ions can easily be taken into the bloodstream through channels that absorb other types of salt. That’s a crucial step, Hurt said. Silver metal particles themselves aren’t terribly likely to make it from the GI tract to the blood, but when they’re transformed into a salt, they’re ushered right through.

From there, Hurt and his team showed that silver ions bind easily with sulfur present in blood proteins, which would give them a free ride through the bloodstream. Some of those ions would eventually end up in the skin, where they’d be exposed to light.

To re-create this end stage, the researchers shined ultraviolet light on collagen gel containing silver ions. The light caused electrons from the surrounding materials to jump onto the unstable ions, returning them to their original state — elemental silver. This final reaction is ultimately what turns patients’ skin blue. The photoreaction is similar to the way silver is used in black and white photography [emphasis mine]. When exposed to light, silver salts on a photographic film reduce to elemental silver and darken, creating an image.

While I find the notion that the body’s reaction to silver is similar to the processing of silver in black and white photography, it’s the discussion about toxicity that most interests me. The scientists at Brown are suggesting that   standard ‘ingestable’ silver could be more dangerous than silver nanoparticles when they are consumed in the body,

This research, however, “would be one piece of evidence that you could treat nanoparticles in the same way as other forms of silver,” Hurt says.

That’s because the bioavailable form of silver — the form that is absorbed into the bloodstream — is the silver salt that’s made in the stomach. Any elemental silver that’s ingested is just the raw material to make that bioavailable salt. So ingesting silver in any form, be it nano or not, would have basically the same effect, Hurt said.

“The concern in this case is the total dose of silver, not what form it’s in,” Hurt said. “This study implies that silver nanoparticles will be less toxic than an equivalent amount of silver salt, at least in this exposure scenario [emphasis mine].”

This research provides more evidence supporting Dr. Andrew Maynard’s contention that creating definitions and regulations for nanomaterials based on size may not be the best approach. Here’s his response to my question (in an Oct. 24, 2011 posting) about the then newly adopted Health Canada definition (which includes size) for nanomaterials,

The problem is that, while the Health Canada is a valiant attempt to craft a definition based on the current state of science, it is still based on a premise – that size within a well defined range is a robust indicator of novel risk – that is questionable [emphasis mine].  Granted, they try to compensate for the limitations of this premise, but the result still smacks of trying to shoehorn the science into an assumption of what is important.

One can only wait as the evidence continues to mount on one side or the other. In the meantime, I don’t one can ever go wrong with BB King, one of the great blues guitar players (Blues Boys Tune),

Toxicology convo heats up: OECD releases report on inhalation toxicity testing and Nature Nanotechnology publishes severe critique of silver toxicity overanalysis

This has to be one of the rawest reports I’ve seen and that’s not a criticism. The OECD (Organization for Economic Cooperation and Development) has released no. 35 in its Series on the Safety of Manufactured Nanomaterials titled, INHALATION TOXICITY TESTING: EXPERT MEETING ON POTENTIAL REVISIONS TO OECD TEST GUIDELINES AND GUIDANCE DOCUMENT.

This report is the outcome of a meeting which took place in fall 2011 according to the July 4, 2012 news item on Nanowerk,

The expert meeting on Inhalation Toxicity Testing for Nanomaterials was held on 19-20 October 2011 in The Hague, hosted by the Netherlands, with the aim of discussing the results of the OECD Sponsorship Programme (under the responsibility of SG3) on this specific topic and addressing issues relevant to inhalation toxicity. Fifty experts from the WPMN as well as the OECD Working Group of the National Coordinators for the Test Guidelines programme (WNT) participated in the meeting.

This is a partial list of recommendations from the report,

Recommendations raised by the speakers for the discussion

7. Various recommendations were raised by the speakers that served as points for discussion. These recommendations do not necessarily reflect a general agreement. …

• “Provide explicit guidance for the generation of aerosols (sample preparation) based on the exposure scenario”. Hans Muijser

• “Generation of a test atmosphere should have workplace characteristics, but should be adapted to adjust for rodent respirability”. Günter Oberdörster

• “A choice for a dry aerosol or a liquid aerosol should depend on the given test substance and planned test approach (hazard- or risk driven)”. Otto Creutzenberg

• “Aerosol characterization should include size distribution, mass, number and morphology of the material”. Günter Oberdörster

• “Mass concentration is not sufficient for comparison of nanomaterials of the same chemical composition”. Flemming Cassee

• “Dry powders will appear as agglomerate upon aerosolization, which needs to be addressed in the sample preparation guidelines”. Flemming Cassee

• “Dissolution behaviour of the test substance should be assessed in physiological fluids mimicking various lung-specific pH ambiences (neutral, acid)”. Otto Creutzenberg

• “Data analysis should include interpretation of aerosol characteristics, NOAEL, risk assessment implications, mode of action and a strategy for dosimetric extrapolation to humans. The inclusion of biokinetic data is important”. Günter Oberdörster

• “Include biokinetics in the guidance, since different distribution patterns in the whole organism are likely dependent on physicochemical characteristics of nanoparticle aerosols and the dose at the target site will therefore be different. This will allow the assessment of accumulation of nanomaterials in the body at low exposure levels and long-term exposure. A way to perform it is by radiolabelled materials, chemical elemental analysis to determine organ concentrations and transmission electron microscopy”. Wolfgang Kreyling. Others who have suggested inclusion of biokinetics or recognized the importance were Otto Creutzenberg, Frieke Kuper, Günter Oberdörster and David Warheit. (p. 13)

You actually see who made the recommendations! Speakers discussed carbon nanotubes, titanium dioxide, cerium oxide, zinc oxide and more, all of which you can read about in summary form in this 38 pp. report.

Meanwhile, Nature Nanotechnology has published an incendiary commentary about nanosilver and the latest request by the European Commission for another study.  Michael Berger has devoted a July 4, 2012 Nanowerk Spotlight article to the commentary,

A commentary by Steffen Foss Hansen and Anders Baun in this week’s Nature Nanotechnology (“When enough is enough”  [behind a paywall]) pointedly asks “when will governments and regulatory agencies stop asking for more reports and reviews, and start taking regulatory action?”

Hansen and Baun, both from the Technical University of Denmark’s Department of Environmental Engineering, take issue with yet another scientific opinion on nanosilver that has been requested by the European Commission in late 2011: “SCENIHR – Request for a scientific opinion on Nanosilver: safety, health and environmental effects and role in antimicrobial resistance” (pdf). Specifically, the EC wants SCENIHR to answer four questions under the general heading of ‘Nanosilver: safety, health and environmental effects, and role in antimicrobial resistance’.

“Most of these questions – and possibly all of them – have already been addressed by no less than 18 review articles in scientific journals, the oldest dating back to 2008, plus at least seven more reviews and reports commissioned and/or funded by governments and other organizations” Hansen tells Nanowerk. “Many of these reviews and reports go through the same literature, cover the same ground and identify many of the same data gaps and research needs.”

Here’s a prediction from Hansen and Baun as to what will be in the next report due in 2013  (from the Nature Nanotechnology commentary When enough is enough in 7, 409–411 (2012) published online  July 1, 2012 [Note: I have removed links and footnotes]),

… we predict that the SCENIHR’s upcoming review will consist of five main sections summarizing: the properties and uses of nanosilver; human and environmental toxicity; microbial resistance; risk assessment; and research needs. We also predict that the SCENIHR’s report will say something along the following lines: “Nanosilver is reportedly one of the most widely used nanomaterials in consumer products today but the scale of production and use is unknown. The antibacterial properties of nanosilver are exploited in a very diverse set of products and applications including dietary supplements, personal care products, powdered colours, textile, paper, kitchenware and food storage.” And like many previous reviews and reports, the new report is likely to cite the Consumer Product Inventory maintained by the Project on Emerging Nanotechnologies.

We acknowledge that answering the question of how to regulate the use of nanosilver is not easy given the different views of the different stakeholders in this debate and the complex regulatory landscape associated with the many applications of nanosilver. …

Arguably, we all want that the pros and cons of regulatory policy options be based on the best available science while taking broader socio-economical and ethical aspects into consideration before deciding on the appropriate regulatory measures concerning human and environmental exposure to nanosilver. Although it is common for independent scientific experts to be commissioned to gather, analyse and review the available scientific information, and to provide recommendations on how to address a given risk, we do not see the need for further reviews. It is time for the European Commission to decide on the regulatory measures that are appropriate for nanosilver. These measures should then be implemented wholeheartedly and their effectiveness monitored.

I predict this commentary will provoke some interesting responses and I will try to add the ones I can find to this posting as they become available.

ETA July 6, 2012: Dexter Johnson weighed in with his July 5, 2012 posting (Note: I have removed a link),

What may make the matter even worse is that we may already have a pretty substantial framework—in the US, at least—on which to base nanosilver regulations, which dates back to the 1950s. It concerned what was called at the time collodial silver, which is essentially what today is called nanosilver.

But getting back to current stagnant state of affairs, it’s hard to know exactly what’s causing the paralysis. It could be concern over implementing regulations in a depressed economy, or just a fear of taking a position. But in both these instances, the lack of action is making the situation worse. …