Tag Archives: Dr. Andrew Maynard

Quality carbon nanotubes

Before launching into this latest item about carbon nanotubes (CNTs), I have an April 11, 2013 posting which offers a brief overview of the topic and a link to my Mar. 14, 2013 posting titled: The long, the short, the straight, and the curved of them: all about carbon nanotubes, which holds an embedded video by Dr. Andrew Maynard where he describes their somewhat ‘unruly’ nature.

These postings will help those unfamiliar with carbon nanotubes to better understand the importance of a June 14, 2014 news item on Nanowerk announcing a new CNT characterization and certification service for single-walled CNTs,

Intertek, a leading quality solutions provider to industries worldwide, today announced a comprehensive facility for characterising key structural and quality parameters of single-walled carbon nanotubes (SWNTs).

A June 12, 2014 Intertek press release, which originated the news item, describes the company’s reasons for adding this to their suite of services,

Carbon nanotubes are very thin tubes of elemental carbon with exceptional mechanical, optical and electrical properties that have the potential to significantly improve the performance of a wide range of materials by altering their fundamental properties. Recent advancements in manufacturing processes mean that SWNTs are now becoming available in sufficient quantity for industrial-scale evaluation and application and so it is increasingly important to be able to verify their quality though robust analytical testing. Applications currently being explored include additives for batteries, composites for the automotive and aerospace industry, electrodes and semiconductor devices such as transistors.

With dimensions of approximately 1/100000th the thickness of a single human hair, SWNTs can present analytical challenges for assessing their quality and structure. No single technique can adequately characterise a nanotube product, and so a diverse set of complementary analytical techniques which have exquisite precision and sensitivity are required. This comprehensive analytical service is commercially available to both manufacturers of nanotubes and to developers who wish to incorporate nanotubes into their products.

It seems to me this is a necessary step on the road to commercializing products utilizing single-walled CNTs.

Tech worries: nanotechnology and nickel on Slate

Dr. Andrew Maynard’s May 20, 2014 article (Small Packages; A new case study on the health risks of nanotech doesn’t tell the whole story) for Slate magazine does much to calm any fears there might be in the wake of a recent case study about the consequences of handling nickel nanoparticles in the workplace,

… The report describes a chemist who developed symptoms that included throat irritation, nasal congestion, facial flushing, and skin reactions to jewelry containing nickel, after starting to work with a powder consisting of nanometer-sized nickel particles. According to the report’s lead author, this is “case one in our modern economy” of exposure to a product of nanotechnology leading to an individual becoming ill.

… And this is why the case of the nickel nanoparticles above needs to be approached with some caution. Many people have an allergic skin reaction to nickel, and research has shown that inhaling nickel particles can cause people to become sensitized to the metal. It’s also well known that fine powders will become airborne more easily than coarse ones when they’re handled, and that the finer the powder you inhale, the more potent it is in your lungs. So it shouldn’t come as a surprise that handling nickel nanopowder in an open lab without exposure controls is not a great idea. In other words, the reported incident was more a case of bad exposure management than nanoparticle risk.

That said, the case does highlight the level of respect with which any new or unusual material should be treated. …

Reinforcing Andrew’s comments about nickel sensitivities, there’s a recent report about smartphones and metal sensitivities. From a May 21, 2014 article by Sarah Knapton for The Telegraph (UK), Note: A link has been removed,

If you have ever noticed swelling, redness, itching or blistering near your cheekbones, ears, jaw or hands, you may be allergic to your phone.

A new study suggests the nickel, chromium and cobalt found in common phones made by BlackBerry, Samsung and LG among others, can cause skin irritations.

Danish and US researchers found at least 37 incidents since 2000 where contact dermatitis was caused by mobile phones.

Here are links to and citations for the nickel case study and to the smartphone paper,

Occupational handling of nickel nanoparticles: A case report by W. Shane Journeay, MD, and Rose H. Goldman, MD. American Journal of Industrial Medicine Article first published online: 8 MAY 2014 DOI: 10.1002/ajim.22344

Mobile Phone Dermatitis in Children and Adults: A Review of the Literature by Clare Richardson, Carsten R. Hamann, Dathan Hamann, and Jacob P. Thyssen. Pediatric Allergy, Immunology, and Pulmonology. Online Ahead of Print: March 5, 2014. doi:10.1089/ped.2013.0308.

The nickel paper is behind a paywall and the smartphone paper is open access.

One comment, the smartphone literature search yielded a small sample, on the other hand, if there isn’t category for the problem, it might not get into reports and be studied.

Getting back to Andrew’s article, it is illuminating and frustratingly opaque (perhaps there was an editing issue?),

Over a couple of days in London last summer, I found myself mulling over a very similar question with a small group of colleagues. We were a pretty eclectic group—engineers, designers, toxicologists, business leaders, academics, policy wonks—but we had one thing in common: We wanted get a better handle on how dangerous realistic products of nanotechnology might be, and how these dangers might be avoided.

… Our approach was to imagine products based on engineered nanomaterials that were technologically feasible and would also have a reasonable chance of surviving a cut-throat economy—products like active food packaging labels that indicated the presence of contaminants; helium-filled balloons with solar cell skins; and materials templated from viruses to generate hydrogen and oxygen from water. We then tried to imagine how these plausible products could potentially release dangerous materials into the environment.

To our surprise, we struggled to come up with scenarios that scared us.

It sounds like this session was organized as a think tank. It would have been nice to know who organized it, who were their invitees, and what was their expertise. On that note, there is this about Andrew at the end of the Slate article,

Andrew Maynard is a leading expert on the responsible development and use of emerging technologies and is the director of the U-M [University of Michigan] Risk Science Center.

Having stumbled across Andrew many times over the years within the ‘nano blogosphere’ and having him kindly answer my amateurish questions about reading research, I feel  confidence when reading his opinion pieces that he is well informed and has carefully considered not only questions I might ask but others as well.

While I might like to know more about that 2013 think tank session in London (UK), this section towards the end of the piece suggests that Andrew has not, in an excess of enthusiasm, thrown in his lot with some hype happy group,

… the case [nickel inhalation] does highlight the level of respect with which any new or unusual material should be treated. This was also one of the conclusions from those two days in London. Just because the risks of many nanotechnology products seem relatively small, doesn’t mean that we can afford to be complacent. There’s still the possibility that someone will create a particularly dangerous new material, or will use a material that seems safe in a dangerous way. As a society we need to be vigilant when it comes to advanced materials, whether they are branded with the nano insignia or not.

As for Knapton article and smartphone research, I haven’t come to any particular conclusions but I am going to keep an eye out for evidence, anecdotal or otherwise. A friend of mine, who sometimes suffers from skin sensitivities, just switched over to her first Blackberry.

Silver ions in the environment

Earlier this week (Feb. 24, 2014), I published a post featuring Dr. Andrew Maynard, Director of the University of Michigan’s Risk Science Center in an introductory video describing seven surprising facts about silver nanoparticles. For those who want to delve more deeply, there’s a Feb. 25, 2014 news item on Nanowerk describing some Swiss research into silver nanoparticles and ions in aquatic environments,

It has long been known that, in the form of free ions, silver particles can be highly toxic to aquatic organisms. Yet to this day, there is a lack of detailed knowledge about the doses required to trigger a response and how the organisms deal with this kind of stress. To learn more about the cellular processes that occur in the cells, scientists from the Aquatic Research Institute, Eawag [Swiss Federal Institute of Aquatic Science and Technology], subjected algae to a range of silver concentrations.

In the past, silver mostly found its way into the environment in the vicinity of silver mines or via wastewater [emphasis mine] emanating from the photo industry. More recently, silver nanoparticles have become commonplace in many applications – as ingredients in cosmetics, food packaging, disinfectants, and functional clothing. Though a recent study conducted by the Swiss National Science Foundation revealed that the bulk of silver nanoparticles is retained in wastewater treatment plants, only little is known about the persistence and the impact of the residual nano-silver in the environment.

The Feb. 25, 2014 Eawag media release, which originated the news item, describes the research in further detail,

Smitha Pillai from the Eawag Department of Environmental Toxicology and her colleagues from EPF Lausanne and ETH Zürich studied the impact of various concentrations of waterborne silver ions on the cells of the green algae Chlamydomonas reinhardtii. Silver is chemically very similar to copper, an essential metal due to its importance in several enzymes. Because of that, silver can exploit the cells’ copper transport mechanisms and sneak into them undercover. This explains why, already after a short time, concentrations of silver in the intracellular fluid can reach up to one thousand times those in the surrounding environment.

A prompt response

Because silver damages key enzymes involved in energy metabolism, even low concentrations can cut photosynthesis and growth rates by a half in just 15 minutes. Over the same time period, the researchers also detected changes in the activity of about 1000 other genes and proteins, which they interpreted as a response to the stressor – an attempt to repair silver-induced damage. At low concentrations, the cells’ photosynthesis apparatus recovered within five hours, and recovery mechanisms were sufficient to deal with all but the highest concentrations tested.

A number of unanswered questions

At first glance, the results are reassuring because the silver concentrations that the algae are subject to in the environment are rarely as high as those applied in the lab, which allows them to recover quickly – at least externally. But the experiments also showed that even low silver concentrations have a significant effect on intracellular processes and that the algae divert their energy to repairing damage incurred. This can pose a problem when other stressors act in parallel, such as increased UV-radiation or other chemical compounds. Moreover, it remains unknown to this day whether the cells have an active mechanism to shuttle out the silver. Lacking such a mechanism, the silver could have adverse effects on higher organisms, given that algae are at the bottom of the food chain.

You can find the researchers’ paper here,

Linking toxicity and adaptive responses across the transcriptome, proteome, and phenotype of Chlamydomonas reinhardtii exposed to silver by Smitha Pillai, Renata Behra, Holger Nestler, Marc J.-F. Suter, Laura Sigg, and Kristin Schirmer. Proceedings of the National Academy of Sciences (PNAS) – early edition 18.February 2014, www.pnas.org/cgi/doi/10.1073/pnas.1319388111

The paper is available through the PNAS open access option.

I have published a number of pieces about aquatic enviornments and wastewater and nanotechnology-enabled products as useful for remediation efforts and as a source of pollution. Here’s a Feb. 28, 2013 posting where I contrasted two pieces of research on silver nanoparticles. The first was research in an aquatic environment and the other concerned wastewater.

Surprising facts about silver nanoparticles from the University of Michigan

Dr. Andrew Maynard, Director of the University of Michigan’s Risk Science Center, has featured seven surprising facts about silver nanoparticles in his latest video in the Risk Bites series. Before getting to the video,here’s an introduction to the topic of silver nanoparticles from a Feb. 18, 2014 posting by Ishani Hewage on the University of Michigan’s Risk Sense blog (Note: A link has been removed),

Silver – known for its germ-killing capabilities – has been used for thousands of years. In recent times though, concerns have been raised over the potential health and environmental risks associated with one particular form of silver that has been used increasingly in a range of products: engineered silver nanoparticle. In this week’s Risk Bites, Andrew Maynard, director of the Risk Science Center, rounds-up seven aspects of silver nanoparticles that might help you weigh up their risks and benefits.

“Silver has long been used for its medicinal properties,” says Andrew. “People used to intentionally dose themselves with silver nanoparticles in the form a silver laced tonic as a cure-all.”

Nowadays, the use of silver nanoparticles is not just limited to the medical field. The military, athletes and manufactures are increasingly using them to develop smart new technologies that inhibit bacterial growth and enhance overall performance.  These microscopically small particles make it easier to get silver into products without compromising them …

Without more ado, here’s the video, ‘7 surprising facts about silver nanoparticles and health':

Both the blog posting and this link will lead you to more information about silver nanoparticles.

Rising from the dead: the inventory of nanotechnology-based consumer products

The inventory of nanotechnology-based consumer products or the Consumer Products Inventory (CPI) is still cited in articles about nanotechnology and its pervasive use in consumer products despite the fact that the inventory was effectively rendered inactive (i.e., dead) in 2009 and that  it was a voluntary system with no oversight, meaning whoever made the submission to the inventory could make any claims they wanted. Now that it’s 2013, things are about to change according to an Oct. 28, 2013 news item on ScienceDaily,

As a resource for consumers, scientists, and policy makers, the Virginia Tech Center for Sustainable Nanotechnology (VTSuN) has joined the Woodrow Wilson International Center for Scholars to renew and expand the Nanotechnology Consumer Product Inventory, an important source of information about products using nanomaterials.

“We want people to appreciate the revolution, such as in electronics and medicine. But we also want them to be informed,” said Nina Quadros, a research scientist at Virginia Tech’s Institute for Critical Technology and Applied Science and associate director of VTSuN, who leads a team of Virginia Tech faculty members and students on this project. Todd Kuiken, senior program associate, and David Rajeski, director of the science and technology innovation program, lead this project at the Wilson Center.

The Oct. 28, 2013 Virginia Tech (Virginia Polytechnic Institute and State University) news release by Susan Trulove (which originated the news item),provides a brief history of the inventory and a description of its revivification,

The Wilson Center and the Project on Emerging Nanotechnology created the inventory in 2005. It grew from 54 to more than 1,000 products, many of which have come and gone. The inventory became the most frequently cited resource, showcasing the widespread applications of nanotechnology. However, in 2009, the project was no longer funded.

“I used it in publications and presentations when talking about all the ways nano is part of people’s lives in consumer products,” said Matthew Hull, who manages the Institute for Critical Technology and Applied Science’s investment portfolio in nanoscale science and engineering, which includes the Center for Sustainable Nanotechnology. “But the inventory was criticized by researchers, regulators, and manufacturers for the lack of scientific information available to support product claims.”

In a meeting with his friend, Andrew Maynard, director of the University of Michigan Risk Science Center, who had initiated the inventory when he was at the Wilson Center, Hull proposed leveraging Institute for Critical Technology and Applied Science and Center for Sustainable Nanotechnology resources to improve the inventory.

“My role was to ask ‘what if’ and [the Virginia Tech Center for Sustainable Nanotechnology] ran with it,” said Hull.

A partnership was formed and, with funding from the Virginia Tech institute, the Center for Sustainable Nanotechnology restructured the inventory to improve the reliability, functionality, and scientific credibility of the database.

“Specifically, we added scientific significance and usefulness by including qualitative and quantitative descriptors for the products and the nanomaterials contained in these products, such as size, concentration, and potential exposure routes,” said Quadros. For example, an intentional exposure route would be the way a medicine is administered. An unintentional exposure would be when a child chews on a toy that has been treated with silver nanoparticles that are used as an antimicrobial. The potential health effect of nanomaterials on children was Quadros doctoral research and she used the inventory to find products designed for children that use nanomaterials, such as plush toys.

“One of the best things about the new version of the inventory is the additional information and the ability to search by product type or the type of nanomaterial,” she said. “When researchers were first attempting to assess the potential environmental impacts of nanotechnology, one main challenge was understanding how these nanomaterials might end up in the environment in the first place. After searching the CPI and seeing the vast applications of nanotechnologies in consumer products it was easier to narrow down scenarios.”

For example, Quadros said many silver nanoparticles are used in clothing for antimicrobial protection, so we can infer that some silver nanoparticles may end up in wastewater treatment plants after clothes washing. This helped justify some of the research on the effects of silver nanoparticle in the biological wastewater treatment processes. Currently, the inventory lists 188 products under the ‘clothing’ category.”

This team also included published scientific data related to those products, where available, and developed a metric to assess the reliability of the data on each inventory entry.

The team interviewed more than 50 nanotechnology experts with more than 350 combined years of experience in nanotechnology, Quadros said. “Their answers provided valuable guidance to help us address diverse stakeholder needs.”

In addition, the site’s users can log in and add information based on their own expertise. “Anyone can suggest edits. The curator and reviewer will approve the edits, and then the new information will go live,” Quadros said.

“We’ve added the horsepower of [the Center for Sustainable Nanotechnology], but opened it by means of crowdsourcing to new information, such as refuting or supporting claims made about products,” Hull said.

“The goal of this work is to create a living, growing inventory for the exchange of accurate information on nano­enabled consumer products,” Quadros said. “Improved information sharing will allow citizens, manufacturers, scientists, policymakers, and others to better understand how nanotechnology is being used in the consumer marketplace,” she said.

As of October 2013,

The inventory currently lists more than 1,600 consumer products that claim to contain nanotechnology or have been found to contain nanomaterials.

Quadros will give a presentation about the inventory at the Sustainable Nanotechnology Organization conference in Santa Barbara on Nov. 3-5 and will present to the U.S. Environmental Protection Agency and the National Science Foundation in the spring.

Key collaborators at Virginia Tech are Sean McGinnis, an associate research professor in the materials science and engineering department; Linsey Marr, professor of civil and environmental engineering; her postdoc, Eric Vejerano, who was instrumental in development of product categories; and Michael Hochella, a university distinguished professor in the geosciences department and Virginia Tech Center for Sustainable Nanotechnology director.

You can find the Consumer Products Inventory here where it is still hosted by the Woodrow Wilson Center’s Project on Emerging Nanotechnologies. The website for the Second Sustainable Nanotechnology Organization Conference where Quadros will be presenting can be found here and is where this conference description can be found,

The objective of this conference is to bring together scientific experts from academia, industry, and government agencies from around the world to present and discuss current research findings on the subject of nanotechnology and sustainability.

The conference program will address the critical aspects of sustainable nanotechnology such as life cycle assessment, green synthesis, green energy, industrial partnerships, environmental and biological fate, and the overall sustainability of engineered nanomaterials. In principle, this involves the fundamental/applied research on the chemistry of producing new green nanomaterials; eco-manufacturing processing of nanomaterials and products, using nanotechnology to benefit society, and examining possible harmful effects of nanotechnology.

The conference will also foster new collaborations between academic and industrial participants. This community of users, researchers and developers of engineered nanomaterials will provide a long-term, scientific assessment of where the science is for sustainable nano, where it should be heading, and what steps academics, government agencies and others can take now to reach targeted goals. In addition, the conference will serve as the platform to initiate the formation of the Sustainable Nanotechnology Organization (SNO), a non-profit, international professional society dedicated to advancing sustainable nanotechnology through education, research, and promotion of responsible development of nanotechnology.

Finally because I can resist no longer, especially so near to Hallowe’en, I guess you could call the ‘renewed’ CPI, a zombie CPI as it’s back from the dead and it needs brains,

Zombies in Moscow, 26 April 2009 Credit: teujene [downloaded from http://en.wikipedia.org/wiki/File:Zombies_in_Moscow.jpg]

Zombies in Moscow, 26 April 2009 Credit: teujene [downloaded from http://en.wikipedia.org/wiki/File:Zombies_in_Moscow.jpg]

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.

The long, the short, the straight, and the curved of them: all about carbon nanotubes

I implied a question in my Mar. 12, 2013 post about the recent announcement from the US National Institute of Occupational Health and Safety (NIOSH) concerning a carbon nanotube toxicity study. I indicated some curiosity about the length of the multi-walled carbon nanotubes studied in this latest research. Coincidentally, Dr. Andrew Maynard (Executive Director of the University of Michigan Risk Science Center answered this implied question in his Mar. 14, 2013 posting about the study (on Andrew’s 2020 Science blog),

The carbon nanotubes in this study were inhaled multi-walled carbon nanotubes with a predominantly long, straight fiber-like morphology.  Mice were exposed at a level of 5 mg/m3 for 5 hours per day, over a 15 day period.

It’s well worth reading Andrew’s posting for the context he provides about the research and for links to further information.

For anyone who wants the short story, multi-walled carbon nanotubes (predominantly the long, straight fibre-type were used in the study) when combined with a known cancer-initiating chemical are more toxic than plain carbon nanotubes. The study has yet to be published but the results were discussed at the Society of Toxicity’s 2013 annual meeting.

Happily, he also provides this charming video (part of his Risk Bites video series) describing carbon nanotubes and their ‘infinite’ variety,

Thank you Andrew for clearing up some of my longstanding questions about carbon nanotubes.

Happy weekend to all!

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),