Posts Tagged ‘nanotoxicology’

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US multicenter (Nano GO Consortium) study of engineered nanomaterial toxicology

Wednesday, May 8th, 2013

Nano Go Consortium is the name they gave a multicenter toxicology study of engineered nanomaterials which has pioneered a new approach  in the US to toxicology research. From the May 6, 2013 news item on Azonano,

For the first time, researchers from institutions around the country have conducted an identical series of toxicology tests evaluating lung-related health impacts associated with widely used engineered nanomaterials (ENMs).

The study [on rodents] provides comparable health risk data from multiple labs, which should help regulators develop policies to protect workers and consumers who come into contact with ENMs.

The May 6, 2013 North Carolina State University news release, which originated the news item, describes the results from one of two studies that were recently published by the Nano GO Consortium in Environmental Health Perspectives,

The researchers found that carbon nanotubes, which are used in everything from bicycle frames to high performance electronics, produced inflammation and inflammatory lesions in the lower portions of the lung. However, the researchers found that the nanotubes could be made less hazardous if treated to remove excess metal catalysts used in the manufacturing process or modified by adding carboxyl groups to the outer shell of the tubes to make them more easily dispersed in biological fluids.

The researchers also found that titanium dioxide nanoparticles also caused inflammation in the lower regions of the lung. Belt-shaped titanium nanoparticles caused more cellular damage in the lungs, and more pronounced lesions, than spherical nanoparticles.

Here’s a link to and a citation for this study on rodents,

Interlaboratory Evaluation of Rodent Pulmonary Responses to Engineered Nanomaterials: The NIEHS NanoGo Consortium by James C. Bonner, Rona M. Silva, Alexia J. Taylor, Jared M. Brown, Susana C. Hilderbrand, Vincent Castranova, Dale Porter, Alison Elder, Günter Oberdörster, Jack R. Harkema, Lori A. Bramble, Terrance J. Kavanagh, Dianne Botta, Andre Nel, and Kent E. Pinkerton. Environ Health Perspect (): .doi:10.1289/ehp.1205693  Published: May 06, 2013

And the information for the other study which this consortium has published,

Interlaboratory Evaluation of in Vitro Cytotoxicity and Inflammatory Responses to Engineered Nanomaterials: The NIEHS NanoGo Consortium by Tian Xia, Raymond F. Hamilton Jr, James C. Bonner, Edward D. Crandall, Alison Elder, Farnoosh Fazlollahi, Teri A. Girtsman, Kwang Kim, Somenath Mitra, Susana A. Ntim, Galya Orr, Mani Tagmount8, Alexia J. Taylor, Donatello Telesca, Ana Tolic, Christopher D. Vulpe, Andrea J. Walker, Xiang Wang, Frank A. Witzmann, Nianqiang Wu, Yumei Xie, Jeffery I. Zink, Andre Nel, and Andrij Holian. Environ Health Perspect (): .doi:10.1289/ehp.1306561 Published: May 06, 2013

Environmental Health Perspectives is an open access journal and the two studies are being offered as ‘early’ publication efforts and will be updated with the full studies at a later date.

Most interesting for me is the editorial offered by four of the researchers involved in the Nano GO Consortium, from the editorial,

Determining the health effects of ENMs presents some unique challenges. The thousands of ENMs in use today are made from an enormous range of substances, vary considerably in size, and take a diversity of shapes, including spheres, cubes, cones, tubes, and other forms. They are also produced in different laboratories across the world using a variety of methods. In the scientific literature, findings on the properties and toxicity of these materials are mixed and often difficult to compare across studies. To improve the reliability and reproducibility of data in this area, there is a need for uniform research protocols and methods, handling guidelines, procurement systems, and models.

…

Although there is still much to learn about the toxicity of ENMs, we are fortunate to start with a clean slate: There are as yet no documented incidences of human disease due to ENM exposure (Xia et al. 2009). Because ENMs are manmade rather than natural substances, we have an opportunity to design, manufacture, and use these materials in ways that allow us to reap the maximum benefits—and minimal risk—to humans.

With $13 million from the American Recovery and Reinvestment Act (2009), the National Institute of Environmental Health Sciences (NIEHS) awarded 13 2-year grants to advance research on the health impacts of ENMs (NIEHS 2013). [emphasis mine] Ten grants were awarded through the National Institutes of Health (NIH) Grand Opportunities program and three were funded through the NIH Challenge Grants program. One goal of this investment was to develop reliable, reproducible methods to assess exposure and biological response to nanomaterials.

…

Within the framework of the consortium, grantees designed and conducted a series of “round-robin” experiments in which similar or identical methods were used to perform in vitro and in vivo tests on the toxicity of selected nanomaterials concurrently at 13 different laboratories.

…

Conducting experiments in a round-robin format within a consortium structure is an unfamiliar approach for most researchers. Although some researchers acknowledged that working collaboratively with such a large and diverse group at times stretched the limits of their comfort zones, the consortium ultimately proved to be “greater than the sum of its parts,” resulting in reliable, standardized protocols that would have been difficult for researchers to achieve by working independently. Indeed, many participants reflected that participating in the consortium not only benefitted their shared goals but also enhanced their individual research efforts. The round-robin approach and the overall consortium structure may be valuable models for other emerging areas of science.

Here’s a link to and a citation for the Consortium’s editorial, which is available in full,

Nano GO Consortium—A Team Science Approach to Assess Engineered Nanomaterials: Reliable Assays and Methods by Thaddeus T. Schug, Srikanth S. Nadadur, and Anne F. Johnson. Environ Health Perspect 121(2013). http://dx.doi.org/10.1289/ehp.1306866 [online 06 May 2013]

I like the idea of researchers working together across institutional and geographical boundaries as that can be a very powerful approach. I hope that won’t devolve into a form of institutionalized oppression where individual researchers are forced out or ignored. In general, it’s the outlier research that often proves to be truly groundbreaking, which often generates extraordinary and informal (and sometimes formal) resistance. For an example of groundbreaking work that was rejected by other researchers who banded together informally, there’s Dan Shechtman, 2011 Nobel Laureate in Chemistry, famously faced hostility from his colleagues for years over his discovery of quasicrystals.

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Gold nanoparticles: more toxic than we thought?

Friday, April 19th, 2013

The research from Stony Brook University (New York State) is a bit disturbing but it should be noted that the tests were done ‘in vitro’ which means they took place in a test tube or a culture dish or somewhere else outside the body. Plus, the conditions for this type of testing are usually quite different than those in real life, e.g. the concentration of gold particles may be significantly higher than the concentration an individual would be exposed to at any one time.

Oddly, earlier this week I responded to a query about information on gold nanoparticles from an artist in New Zealand by noting that I had never come across any toxicity or toxicology testing studies but mentioned that mine is a passive approach. I scan aggregators and other news sources but I don’t usually seek out specific  information about toxicity/toxicology.

So here it is, the first gold nanoparticle toxicity study I’ve featured on this blog in almost five years,from an Apr. 18, 2013 news item on ScienceDaily,

New research reveals that pure gold nanoparticles found in everyday items such as personal care products, as well as drug delivery, MRI contrast agents and solar cells can inhibit adipose (fat) storage and lead to accelerated aging and wrinkling, slowed wound healing and the onset of diabetes. [emphasis mine] The researchers, led by Tatsiana Mironava, a visiting assistant professor in the Department of Chemical and Molecular Engineering at Stony Brook University, detail their research in the journal Nanotoxicology.

The Stony Brook University Apr. 18, 2013 news release, which originated the news item, provides details,

Together with co-author Dr. Marcia Simon, Professor of Oral Biology and Pathology at Stony Brook University, and Director of the University’s Living Skin Bank, a world-class facility that has developed skin tissue for burn victims and various wound therapies, the researchers tested the impact of nanoparticles in vitro on multiple types of cells, including adipose (fat) tissue, to determine whether their basic functions were disrupted when exposed to very low doses of nanoparticles. Subcutaneous adipose tissue acts as insulation from heat and cold, functions as a reserve of nutrients, and is found around internal organs for padding, in yellow bone marrow and in breast tissue.

They discovered that the human adipose-derived stromal cells – a type of adult stem cells – were penetrated by the gold nanoparticles almost instantly and that the particles accumulated in the cells with no obvious pathway for elimination. The presence of the particles disrupted multiple cell functions, such as movement; replication (cell division); and collagen contraction; processes that are essential in wound healing.

According to the researchers, the most disturbing finding was that the particles interfered with genetic regulation, RNA expression and inhibited the ability to differentiate into mature adipocytes or fat cells. “Reductions caused by gold nanoparticles can result in systemic changes to the body,” said Professor Mironava. “Since they have been considered inert and essentially harmless, it was assumed that pure gold nanoparticles would also be safe. Evidence to the contrary is beginning to emerge.”

The study was also the first to,

… demonstrate the impact of nanoparticles on adult stem cells, which are the cells our body uses for continual organ regeneration. It revealed that adipose derived stromal cells involved in regeneration of multiple organs, including skin, nerve, bone, and hair, ignored appropriate cues and failed to differentiate when exposed to nanoparticles. The presence of gold nanoparticles also reduced adiponectin, a protein involved in regulating glucose levels and fatty acid breakdown, which helps to regulate metabolism.

“We have learned that careful consideration and the choice of size, concentration and the duration of the clinical application of gold nanoparticles is warranted,” said Professor Mironava. “The good news is that when the nanoparticles were removed, normal functions were eventually restored.”

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

Gold nanoparticles cellular toxicity and recovery: Adipose Derived Stromal cells by Tatsiana Mironava, Michael Hadjiargyrou, Marcia Simon, & Miriam H. Rafailovich. Nanotoxicology. Posted online on February 8, 2013. (doi:10.3109/17435390.2013.769128)

As for the aging and wrinkling, you can see the basis for the claims in the paper’s abstract,

Gold nanoparticles (AuNPs) are currently used in numerous medical applications. Herein, we describe their in vitro impact on human adipose-derived stromal cells (ADSCs) using 13 nm and 45 nm citrate-coated AuNPs. In their non-differentiated state, ADSCs were penetrated by the AuNPs and stored in vacuoles. The presence of the AuNPs in ADSCs resulted in increased population doubling times, decreased cell motility and cell-mediated collagen contraction. [emphasis mine] The degree to which the cells were impacted was a function of particle concentration, where the smaller particles required a sevenfold higher concentration to have the same effect as the larger ones. Furthermore, AuNPs reduced adipogenesis as measured by lipid droplet accumulation and adiponectin secretion. These effects correlated with transient increases in DLK1 and with relative reductions in fibronectin. Upon removal of exogenous AuNPs, cellular NP levels decreased and normal ADSC functions were restored. As adiponectin helps regulate energy metabolism, local fluctuations triggered by AuNPs can lead to systemic changes. Hence, careful choice of size, concentration and clinical application duration of AuNPs is warranted.
The researchers’ paper is behind a paywall.

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‘Nano fest’ at the 245th meeting of the American Chemical Society

Tuesday, April 9th, 2013

The American Chemical Society’s (ACS) 245th meeting (April 7 – 11, 2013) features a few items about nanotechnology: the funding of it and the toxicological testing of it, in two separate news items which bear a ‘political’ link.

An April 9, 2013 news item on Azonano tells of concerns regarding recent funding cuts resulting from the US budget sequestration,

Speaking at the 245th National Meeting & Exposition of the American Chemical Society, the world’s largest scientific society, A. Paul Alivisatos, Ph.D., expressed concern that the cuts come when nanotechnology is poised to deliver on those promises. He told the meeting, which continues through Thursday, that ill-conceived cuts could set back America’s progress in nanotechnology by decades.

“The National Science Foundation announced that they will issue a thousand fewer new grants this year because of sequestration,” said Alivisatos, referring to the across-the-board mandatory federal budget cuts that took effect on March 1. “What it means in practice is that an entire generation of early career scientists, some of our brightest and most promising scientists, will not have the funding to launch their careers and begin research properly, in the pathway that has established the United States as leader in nanotechnology research. It will be a setback, perhaps quite serious, for our international competitiveness in this key field.”

Alivisatos described applications of nanotechnology that can help reduce fossil fuel consumption and the accompanying emissions of carbon dioxide, the main greenhouse gas. He is professor of chemistry and materials science and the Larry and Diane Bock Professor of Nanotechnology at the University of California at Berkeley, director of the Lawrence Berkeley National Laboratory and co-editor of the ACS journal Nano Letters. …

Alivisatos expressed concern, however, that cuts in federal funding will take a heavy toll on the still-emerging field. He explained that the reductions stand to affect scientists at almost every stage of making contributions to society. Young scientists, for instance, will find it more difficult to launch research programs in new and promising fields.[emphases mine]  Established scientists will have to trim research programs, and may not have the money to explore promising new leads.

“We haven’t been able to communicate adequately with the public and policymakers, and explain the impact of what may sound like small and unimportant cuts in funding.” Alivisatos said. “A 5 percent reduction in funding — well, to the public, it seems like nothing. In reality, these cuts will be applied in ways that do maximal damage to our ability to be globally competitive in the future.”

Coincidentally or not,  the ACS had placed an Apr. 8, 2013 news release on EurekAlert highlighting some work in the field of nanotoxicology led by a ‘young’ scientist (I imagine she received her funding prior to sequestration) doing some exciting work,

Earlier efforts to determine the health and environmental effects of the nanoparticles that are finding use in hundreds of consumer products may have produced misleading results by embracing traditional toxicology tests that do not take into account the unique properties of bits of material so small that 100,000 could fit in the period at the end of this sentence.

That was among the observations presented here today at the 245th National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society, by one of the emerging leaders in nanoscience research. The talk by Christy Haynes, Ph.D., was among almost 12,000 presentations at the gathering, which organizers expect to attract more than 14,000 scientists and others.

Haynes delivered the inaugural Kavli Foundation Emerging Leader in Chemistry Lecture at the meeting, … Sponsored by the Kavli Foundation, the Emerging Leaders Lectures recognize the work of outstanding young chemical scientists. [emphasis mine] …

“Christy Haynes is the perfect scientist to launch this prestigious lecture series,” said Marinda Li Wu, Ph.D., president of the ACS. “Haynes’ research is making an impact in the scientific community in efforts to use nanoparticles and nanotechnology in medicine and other fields. And that research has sparked the popular imagination, as well. Haynes was included in Popular Science‘s ‘Brilliant 10′ list, a group of ‘geniuses shaking up science today.’ [emphasis mine] We are delighted to collaborate with the Kavli Foundation in highlighting the contributions of such individuals.”

Moving on from politics to science, the EurekAlert Apr. 8, 2013 news release offers a standard discussion regarding gold and nanoparticle gold before highlighting the aspect that marks Haynes’ fresh approach to toxicity at the nanoscale,

A 1-ounce nugget of pure gold, for instance, has the same chemical and physical properties as a 2-ounce nugget or a 27-pound gold bar. For nanoparticles, however, size often dictates the physical and chemical properties, and those properties change as the size decreases.

Haynes said that some of the earlier nanotoxicology tests did not fully take those and other factors into account when evaluating the effects of nanoparticles. In some cases, for instance, the bottom line in those tests was whether cells growing in laboratory cultures lived or died after exposure to a nanoparticle.

“While these results can be useful, there are two important limitations,” Haynes explained. “A cell can be alive but unable to function properly, and it would not be apparent in those tests. In addition, the nature of nanoparticles — they’re more highly reactive — can cause ‘false positives’ in these assays.”

Haynes described a new approach used in her team’s work in evaluating the toxicity of nanoparticles. It focuses on monitoring how exposure to nanoparticles affects a cell’s ability to function normally, rather than just its ability to survive the exposure. In addition, they have implemented measures to reduce “false-positive” test results, which overestimate nanoparticle toxicity. One of the team’s safety tests, for instance, determines whether key cells in the immune system can still work normally after exposure to nanoparticles. In another, the scientists determine whether bacteria exposed to nanoparticles can still communicate with each other, engaging in the critical biochemical chatter that enables bacteria to form biofilms, communities essential for them to multiply in ways that lead to infections.

“So far, we have found that nanoparticles made of silver or titanium may be the most problematic, though I would say that neither is as bad as some of the alarmist media speculations, especially when they are stabilized appropriately,” said Haynes. “I think that it will be possible to create safe, stable coatings on nanoparticles that will make them stable and allow them to leave the body appropriately. We need more research, of course, in order to make informed decisions.”

Hopefully, you find this mixture of science and politics as interesting as I do.

ETA Apr. 10, 2013: Dexter Johnson has commented on and provided some contextual information about nanotechnology research funding in the US in response to the Alivisatos talk about sequestration and its possible impact on nanotechnology research in Apr. 9, 2013 posting (Note: A link has been removed),

There is always room for the argument that reassessing and reallocating resources can help make nanotechnology more efficient and productive, something observers have pointed out in NASA taking on less of its own nanotechnology research and outsourcing it to other government organizations. But it’s not always easy to tell which fundamental research projects will turn out to have been the most productive, and worse, the timing of these cuts could be extremely painful as they occur at a critical moment for U.S. nanotechnology.

Dexter’s piece is well worth reading.

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Crowdfunding nanotoxicology research and determining the results in advance

Friday, February 8th, 2013

A Feb. 7, 2013 news item on Nanowerk highlights an initiative by a not-for-profit agency, As You Sow, to crowdfund nanotoxicology research (Note: Links have been removed),

“Slipping Through the Cracks: An Issue Brief on Nanomaterials in Food” was released yesterday by As You Sow, a nonprofit organization that promotes corporate responsibility and environmental health. The brief includes results of a survey of 2,500 food companies about their use of nanomaterials in food products, as well as laboratory results showing titanium dioxide (TiO2) nanoparticles in the white powdered sugar that coats Dunkin’ Donuts Powdered Cake Donuts and Hostess Donettes.

Intent on testing more common food products, As You Sow has simultaneously launched a crowdfunding campaign on Indiegogo. “We plan to raise enough money to test M&M’s, Pop-Tarts, and Trident gum for nanomaterials,” said As You Sow CEO Andrew Behar.

The organization’s Slipping Through the Cracks: An Issue Brief on Nanomaterials in Foods can be found here. Clicking on the publication’s  Download the report (PDF) link produces a form which needs to be filled out prior to receiving it.  From the ‘Slipping Through the Cracks’  webpage,

Slipping Through the Cracks is designed to inform companies, investors, and consumers about the emerging use of engineered nanomaterials in food and food related products. It highlights the potential risks of nanotechnology for companies who are knowingly or unknowingly using it in their products and for public health.

As You Sow and other leading investors surveyed 25,000 food manufacturers and tested a range of popular donuts; the results of both inquiries proved that nanomaterials are currently being used in food products. [emphases mine]

The terminology “leading investors” is an interesting choice. Is that because activist or civil society member is considered more pejorative? From the As You Sow About Us page (Note: Links have been removed),

Founded in 1992, As You Sow promotes environmental and social corporate responsibility through shareholder advocacy, coalition building, and innovative legal strategies. Our efforts create large-scale systemic change by establishing sustainable and equitable corporate practices.

As You Sow was founded on the belief that many environmental and human rights issues can be resolved by increased corporate responsibility. As investor representatives, we communicate directly with corporate executives to collaboratively develop and implement business models that reduce risk, benefit brand reputation, and protect long term shareholder value while simultaneously bringing about positive change for the environment and human rights.

How does this work and from where do they get their funding? It’s hard to imagine an investor in IBM or Proctor & Gamble or Facebook or Monsanto or … contacting these folks and asking them to ensure corporate social responsibility and investigate nanomaterials in food. Alternatively, which food or other type of company asked them to check for nanomaterials in donuts? The whole endeavour does seems a bit odd.

In any event, As You Sow’s Feb. 6, 2013 news release about the Indiegogo campaign makes some largely unexceptional comments,

Nanomaterials have been heralded as having the potential to revolutionize the food industry – from enabling production of creamy liquids that contain no fat, to enhancing flavors, improving supplement delivery, providing brighter colors, keeping food fresh longer, or indicating when it spoils. Yet few, if any, studies adequately demonstrate the safety of nanoparticles in food. In fact, scientists are still investigating how nanoparticles will react in the body and what testing methodologies are appropriate to determine this.

“There has been a lot of buzz about the potential for nanomaterials in food, but very little information about the risks to public health,” said Danielle Fugere, As You Sow President and co‐author of the brief. “Much deeper scientific inquiry is needed to prove nanomaterials are safe before they continue to be sold commercially.” [emphasis mine]

“Deeper scientific inquiry” sounds like an excellent idea unfortunately the folks at As You Sow seem to believe that the ‘scientific inquiry’ finding proof of a predetermined outcome, from the Protect Kids from Nanomaterials in Sweets crowdfunding campaign page on Indiegogo,

Kid-friendly foods like M&Ms & Pop-Tarts may contain dangerous nanoparticles, which we found in Dunkin Donuts. Help us test more foods & keep your family safe.

As You Sow found nanomaterials in Dunkin Donuts as noted in their Feb. 6, 2013 news release. Strangely that news release does not contain any information about research proving that the nano titanium dioxide on the donuts is dangerous to anyone’s health. There is not a single piece of research or expert cited. This seems less like a scientific inquiry and more like pseudo-science. The fact that there are some dangerous nanomaterials means that all nanomaterials are dangerous and and, if upon testing, any nanomaterials are found in a foodstuff that means the foodstuff is dangerous to our health.

From a semiotic perspective, there’s a wealth of imagery and signification to work with, far too much for this post.

Shockingly, this group has raised almost 25% of the funds they’ve requested with 33 days left in the campaign.

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The yin and the yang of carbon nanotubes and toxicity

Wednesday, January 16th, 2013

 

Illustration courtesy of the University College of London (UCL). Downloaded from http://www.ucl.ac.uk/news/news-articles/0113/130115-chemistry-resolves-toxic-concerns-about-carbon-nanotubes

Illustration courtesy of the University College of London (UCL). Downloaded from http://www.ucl.ac.uk/news/news-articles/0113/130115-chemistry-resolves-toxic-concerns-about-carbon-nanotubes

Researchers at the University College of London (UCL), France’s Centre national de la recherche scientifique (CNRS), and Italy’s University of Trieste have determined that carbon nanotube toxicity issues can be addressed be reducing their length and treating them chemically. From the Jan. 15,2013 news item on ScienceDaily,

In a new study, published January 15 [2013] in the journal Angewandte Chemie, evidence is provided that the asbestos-like reactivity and pathogenicity reported for long, pristine nanotubes can be completely alleviated if their surface is modified and their effective length is reduced as a result of chemical treatment.

First atomically described in the 1990s, carbon nanotubes are sheets of carbon atoms rolled up into hollow tubes just a few nanometres in diameter. Engineered carbon nanotubes can be chemically modified, with the addition of chemotherapeutic drugs, fluorescent tags or nucleic acids — opening up applications in cancer and gene therapy.

Furthermore, these chemically modified carbon nanotubes can pierce the cell membrane, acting as a kind of ‘nano-needle’, allowing the possibility of efficient transport of therapeutic and diagnostic agents directly into the cytoplasm of cells.

Among their downsides however, have been concerns about their safety profile. One of the most serious concerns, highlighted in 2008, involves the carcinogenic risk from the exposure and persistence of such fibres in the body. Some studies indicate that when long untreated carbon nanotubes are injected to the abdominal cavity of mice they can induce unwanted responses resembling those associated with exposure to certain asbestos fibres.

In this paper, the authors describe two different reactions which ask if any chemical modification can render the nanotubes non-toxic. They conclude that not all chemical treatments alleviate the toxicity risks associated with the material. Only those reactions that are able to render carbon nanotubes short and stably suspended in biological fluids without aggregation are able to result in safe, risk-free material.

Here’s a citation and link for this latest  research, from the ScienceDaily news item where you can also read the lead researcher’s comments about carbon nanotubes, safety, and unreasonable proposals to halt production,

Hanene Ali-Boucetta, Antonio Nunes, Raquel Sainz, M. Antonia Herrero, Bowen Tian, Maurizio Prato, Alberto Bianco, Kostas Kostarelos. Asbestos-like Pathogenicity of Long Carbon Nanotubes Alleviated by Chemical Functionalization. Angewandte Chemie International Edition, 2013; DOI: 10.1002/anie.201207664

The article is behind a paywall. I have mentioned long carbon nanotubes and their resemblance to asbestos fibres in several posts. The  Oct. 26, 2009 posting [scroll down about 1/3 of the way] highlights research which took place after the study where mice had carbon nanotubes injected into their bellies; in this second piece of research they inhaled the nanotubes.

ETA Jan. 21, 2013: Dexter Johnson gives context and commentary about this latest research into long multiwalled nanotubes (MWNTs) which he sums up as the answer to this question “What if you kept the MWNTs short?”  in a Jan. 18, 2013 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website)

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

Wednesday, August 8th, 2012

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.)

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Environment influences nanomaterial reactions to biological cells

Tuesday, July 31st, 2012

The discussion I’ve seen around nanomaterials and toxicological effects has largely centered on shapes, size, aggregate/agglomerate, etc. By contrast, Carl Walkey’s July 24, 2012 Nanowerk Spotlight essay focuses on nanomaterial surfaces, bare or coated with serum proteins (Note: I have removed links),

Biomolecule adsorption to nanomaterials is usually studied from physiological fluids with suspended biomolecules. Examples include blood serum/plasma, pulmonary surfactant, and synovial fluid. However, until now the amount of those molecules has not been considered relevant to the study. In a recent article appearing in ACS Nano (“Effects of the Presence or Absence of a Protein Corona on Silica Nanoparticle Uptake and Impact on Cells”), Drs. Anna Salvati, Kenneth Dawson, and their colleagues at the University College in Dublin, Ireland, show that if nanoparticles are exposed directly to cells in the absence of suspended biomolecules, the nanoparticles will extract biomolecules directly from cells themselves.

In their experiments, the team exposed silica nanoparticles to cells in two sets. One set was introduced into cell culture media that was supplemented with the usual concentration of fetal bovine serum, and the other into media that had no serum additives. They then incubated both sets of particles with a lung cancer cell line and measured particle uptake kinetics and cell adhesion. Nanoparticles treated under both conditions associated with cells. However, the particles that were incubated in media alone associated to a much greater extent than those that were first incubated in serum. This indicates that the affinity of the bare nanoparticle surface to the cell is much higher than the affinity of an equivalent surface that is coated with serum proteins. [emphasis mine] Similar observations are reported before for other systems, where it was also found that uptake under serum-free conditions is higher.

Moe specifically,

“When the nanomaterial is put in contact with a physiological environment, it is given a menu of possible biomolecules to adsorb” explains Dawson. “It will essentially go shopping for the biomolecules that it wants. Over time, it will exchange with the environment until it finds the things that it really likes most. If you don’t give it enough biomolecules in the form of serum, it will extract components from the cells themselves.”

The same silica nanoparticles exposed to cells in the two different conditions had different cellular responses as well. Most of the serum-coated particles were taken up within vesicles in the cell cytoplasm and produced no overt signs of toxicity. In contrast, the particles without a serum coating adhered to the cell surface to a greater extent, were present in vesicles, and some were also found free-floating in the cytoplasm. Exposure to particles in absence of serum significantly decreased cell viability and caused cells to take on a rounded morphology that is indicative of cell death. Dawson believes that cell death from uncoated particles is the result of strong interactions between the particle surface and the cell surface, which may damage the cell membrane, and/or initiate aberrant signaling cascades. When serum proteins are adsorbed to the nanoparticles, they ‘passivate’ the surface and limit direct nanomaterial-cell interactions.

When considering the early interactions of a nanomaterial with a cell, Dawson points out that one cannot think of the nanomaterial alone. Instead, one must think of the nanoparticle and its adsorbed biomolecules as a fundamental unit. [emphasis mine]

Most importantly,

Dawson believes that researchers must pay closer attention to the composition of the biomolecular environment surrounding the particles and cells when performing in vitro experiments. In other words, it is as important to consider the composition of the biomolecules in the media as it is to consider the chemical nature of the nanoparticle and the cell type. [emphasis mine]

“What’s absolutely clear is that depending on the type of dispersion that you make up, whether you add 10% serum or 20% serum, you get different levels of cell uptake” says Dawson. “Indeed, you get different levels of damage as well. It is therefore not meaningful to say that the nanoparticle is or is not toxic in that simplistic way. You can make a material toxic if you really want to make it toxic. You can make many materials damage cells simply because these have high surface energy. However, in a realistic physiological environment, part of the particle surface is covered and so that kind of damage would not be applicable.”

I encourage anyone who’s interested in nanotoxicology to read Walkey’s essay in full as I’ve excerpted only a portion.

BTW, Carl Walkey is a PhD graduate student at the University of Toronto and a member of the Integrated Nanotechnology & Biomedical Sciences Laboratory (INBS). I last mentioned Walkey in my July 12, 2012 posting about his Nanowerk Spotlight essay on nanotoxicology and animal studies.

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Free the rats, mice, and zebrafish from the labs—replace them with in vitro assays to test nanomaterial toxcicity

Thursday, July 12th, 2012

The July 9, 2012 Nanowerk Spotlight article by Carl Walkey (of the University of Toronto) focuses on research by Dr. André Nel and his coworkers at the California NanoSystems Institute (CNSI) and the University of California Los Angeles (UCLA) on replacing small animal model testing for nanomaterial toxicity with in vitro assays,

Currently, small animal models are the ‘gold standard’ for nanomaterial toxicity testing. In a typical assessment, researchers introduce a nanomaterial into a series of laboratory animals, generally rats or mice, or the ‘workhorse’ of toxicity testing – zebrafish (see: “High content screening of zebrafish greatly speeds up nanoparticle hazard assessment”). They then examine where the material accumulates, whether it is excreted or retained in the animal, and the effect it has on tissue and organ function. A detailed understanding often requires dozens of animals and can take many months to complete for a single formulation. The current infrastructure and funding for animal testing is insufficient to support the evaluation of all nanomaterials currently in existence, let alone those that will be developed in the near future. This is creating a growing deficit in our understanding of nanomaterial toxicity, which fuels public apprehension towards nanotechnology.

Dr. André Nel and his coworkers at the California NanoSystems Institute (CNSI) and the University of California Los Angeles (UCLA) are taking a fundamentally different approach to nanomaterial toxicity testing.

Nel believes that, under the right circumstances, resource-intensive animal experiments can be replaced with comparatively simple in vitro assays.  The in vitro assays are not only less costly, but they can also be performed using high throughput (HT) techniques. By using an in vitro HT screening approach, comprehensive toxicological testing of a nanomaterial can be performed in a matter of days. Rapid information gathering will allow stakeholders to make rational, informed decisions about nanomaterials during all phases of the development process, from design to deployment.

I’ve excerpted a brief description of Nel’s approach,

Rather than using in vitro systems as direct substitutes for the in vivo case, Nel is using a mechanistic approach to connect cellular responses to more complex biological responses, attempting to employ mechanisms that are engaged at both levels and reflective of specific nanomaterial properties.

“You need to align what you test at a cellular level with what you want to know at the in vivo” says Nel. “If oxidative stress at the cellular level is a key initiating element, then by screening for this outcome in cells you more are likely to yield something more predictive of the in vivo outcome. We can do a lot of our mechanistic work at an implementation level that allows development of predictive screening assays.”

By measuring many relevant mechanistic responses, and integrating the results, Nel believes that the in vivo behavior of a nanomaterial can be accurately predicted, provided that enough thinking goes into the devising the systems biology approach to safety assessment.

According to Walkey’s article, this approach could result in a ‘reverse’ nanomaterial development process,

Nel’s approach will influence not only the way in which nanomaterial toxicity is assessed, but also the way in which nanomaterials are developed. Currently, nanomaterials are designed to meet the need of a particular application. Toxicity is then evaluated retrospectively. Formulations that exhibit unacceptable toxicity at that point may be abandoned after a significant investment in development. Because Nel’s approach generates toxicity information much faster than traditional techniques, it will be possible to integrate toxicity during the design of a new nanomaterial. The proactive characterization of nanomaterial toxicity will provide feedback during the design process, producing formulations that maximize efficacy and minimize risk.

This is a very interesting article (illustrated with images and peppered with accessibly explanations of the issues) for anyone following the ‘nanomaterial toxicology’ story.

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

Thursday, July 5th, 2012

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. …

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

Tuesday, July 3rd, 2012

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.

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