Tag Archives: multi-walled carbon nanotubes

Multi-walled carbon nanotubes and blood clotting

There’s been a lot of interest in using carbon nanotubes (CNTs) for biomedical applications such as drug delivery. New research from Trinity College Dublin (TCD) suggests that multi-walled carbon nanotubes (MWCNTs) may have some limitations when applied to biomedical uses. From a Jan. 20, 2014 news item on Nanowerk (Note: A link has been removed),

Scientists in the School of Pharmacy and Pharmaceutical Sciences in Trinity College Dublin, have made an important discovery about the safety issues of using carbon nanotubes as biomaterials which come into contact with blood. The significance of their findings is reflected in their paper being published as the feature story and front page cover of the international, peer-reviewed journal Nanomedicine (“Blood biocompatibility of surface-bound multi-walled carbon nanotubes”).

A Jan. 19, 2015 TCD press release, which originated the news item, offers a good description of the issues around blood clotting and the research problem (nonfunctionalized CNTs and blood compartibility) the scientists were addressing (Note: Links have been removed),

When blood comes into contact with foreign surfaces the blood’s platelets are activated which in turn leads to blood clots being formed. This can be catastrophic in clinical settings where extracorporeal circulation technologies are used such as during heart-lung bypass, in which the blood is circulated in PVC tubing outside the body. More than one million cardiothoracic surgeries are performed each year and while new circulation surfaces that prevent platelet activation are urgently needed, effective technologies have remained elusive.

One hope has been that carbon nanotubes, which are enormously important as potentially useful biomedical materials, might provide a solution to this challenge and this led the scientists from the School of Pharmacy and Pharmaceutical Sciences in collaboration with Trinity’s School of Chemistry and with colleagues from UCD and the University of Michigan in Ann Arbour to test the blood biocompatibility of carbon nanotubes. They found that the carbon nanotubes did actually stimulate blood platelet activation, subsequently leading to serious and devastating blood clotting. The findings have implications for the design of medical devices which contain nanoparticles and which are used in conjunction with flowing blood.

Speaking about their findings, Professor Marek Radomski, Chair of Pharmacology, Trinity and the paper’s senior author said: “Our results bear significance for the design of blood-facing medical devices, surface-functionalised with nanoparticles or containing surface-shedding nanoparticles. We feel that the risk/benefit ratio with particular attention to blood compatibility should be carefully evaluated during the development of such devices. Furthermore, it is clear that non-functionalised carbon nanotubes both soluble and surface-bound are not blood-compatible”.

The press release also quotes a TCD graduate,

Speaking about the significance of these findings for Nanomedicine research, the paper’s first author Dr Alan Gaffney, a Trinity PhD graduate who is now Assistant Professor of Anaesthesiology in Columbia University Medical Centre, New York said: “When new and exciting technologies with enormous potential benefits for medicine are being studied, there is often a bias towards the publication of positive findings. [emphasis mine] The ultimate successful and safe application of nanotechnology in medicine requires a complete understanding of the negative as well as positive effects so that un-intended side effects can be prevented. Our study is an important contribution to the field of nanomedicine and nanotoxicology research and will help to ensure that nanomaterials that come in contact with blood are thoroughly tested for their interaction with blood platelets before they are used in patients.”

Point well taken Dr. Gaffney. Too often there’s an almost euphoric quality to the nanomedicine discussion where nanoscale treatments are described as if they are perfectly benign in advance of any real testing. For example, I wrote about surgical nanobots being used in a human clinical trial in a Jan. 7, 2015 post which features a video of the researcher ‘selling’ his idea. The enthusiasm is laudable and necessary (researchers work for years trying to develop new treatments) but as Gaffney notes there needs to be some counter-ballast and recognition of the ‘positive bias’ issue.

Getting back to the TCD research, here’s a link to and a citation for the paper (or counter-ballast),

Blood biocompatibility of surface-bound multi-walled carbon nanotubes by Alan M. Gaffney, MD, PhD, Maria J. Santos-Martinez, MD, Amro Satti, Terry C. Major, Kieran J. Wynne, Yurii K. Gun’ko, PhD, Gail M. Annich, Giuliano Elia, Marek W. Radomski, MD. January 2015 Volume 11, Issue 1, Pages 39–46 DOI: http://dx.doi.org/10.1016/j.nano.2014.07.005 Published Online: July 26, 2014

This paper is open access.

Government of Canada’s risk assessment for multi-walled carbon nanotubes

Lynn Bergeson’s Jan. 15, 2015 post on the Nanotechnology Now website mentions a newly issued Canadian risk assessment for multi-walled carbon nanotubes (MWCNTs),

Canada announced on January 9, 2015, that the New Substances Program has published six new risk assessment summaries for chemicals and polymers, including a summary for multi-wall carbon nanotubes.

… Environment Canada and Health Canada conduct risk assessments on new substances. These assessments include consideration of information on physical and chemical properties, hazards, uses, and exposure to determine whether a substance is or may become harmful to human health or environment as set out in Section 64 of the Canadian Environmental Protection Act, 1999 (CEPA 1999), and, if harm is suspected, to introduce any appropriate or required control measures. …

Here’s more information from the Summary of Risk Assessment Conducted Pursuant to subsection 83(1) of the Canadian Environmental Protection Act, 1999
Significant New Activity No. 17192: Multi-wall carbon nanotubes webpage,

Substance Identity

The substance is a short tangled multi-walled carbon nanotube that can be classified as a nanomaterial. [emphasis mine]

Notified Activities

The substance is proposed to be manufactured in or imported into Canada in quantities greater than 1000 kg/yr for use as an additive in plastics.

Environmental Fate and Behaviour

Based on its physical and chemical properties, if released to the environment, the substance will tend to partition to water, sediment, soil, and ambient air. The substance is expected to be persistent in these compartments because it is a stable inorganic chemical that will not degrade. Based on the limited understanding of uptake by organisms, more data is required to assess the bioaccumulation potential of this substance at the current schedule notification.

Ecological Assessment

Based on the available hazard information on the substance and surrogate data on structurally related nanomaterials, the substance has low to moderate (1-100 mg/L) acute toxicity in aquatic life (fish/daphnia/algae). The predicted no effect concentration was calculated to be less than 1 mg/L using the ErC50 from the most sensitive organism (P. subcapitata), which was used to estimate the environmental risk.

The notified and other potential activities in Canada were assessed to estimate the environmental exposure potential of the substance throughout its life cycle. Environmental exposure from the notified activities was determined through a conservative generic single point-source release blending scenario. The predicted environmental concentration for notified activities is estimated to be 2.1 µg/L.

Based on the current use profile in conjunction with low to moderate ecotoxicity endpoints, the substance is unlikely to cause ecological harm in Canada.

However, based on the current understanding of carbon nanotubes and nanomaterials in general, a change in the use profile of the substance (SNAc No. 17192) may significantly alter the exposure resulting in the substance becoming harmful to the environment.  Consequently, more information is necessary to better characterize potential environmental risks.

Human Health Assessment

Based on the available hazard information on the substance, the substance has a low potential for acute toxicity by the oral, dermal and inhalation routes of exposure (oral and dermal LD50 greater than 2000 mg/kg bw; inhalation LC50 greater than 1.3 mg/m3). It is a severe eye irritant (MAS score = 68), a mild skin irritant (PII = 1.08) and at most a weak sensitizer (because the positive control was tested at a concentration 10X higher than the test substance). It is not an in vitro mutagen (negative in a mammalian cell gene mutation test and in a mammalian chromosome aberration test).  Therefore the substance is unlikely to cause genetic damage.

Hazards related to substances used in the workplace should be classified accordingly under the Workplace Hazardous Materials Information System (WHMIS).

However, based on the available information on structurally related nanomaterials, the substance may cause respiratory toxicity, immunotoxicity, cardiovascular toxicity and carcinogenicity following oral and inhalation exposure.

When used as an additive in plastics, the substance is expected to be manufactured in or imported into Canada encapsulated in a solid polymer matrix. The potential site of exposure to the substance is expected to be within industrial facilities. Therefore, direct exposure of the general population is expected to be low. No significant environmental release is anticipated due to the specialized use under this notification and therefore indirect exposure of the general population from environmental media is also expected to be low. However, if the substance is produced in different forms (e.g. liquid polymer form), applied in different formulations or used in any other potential applications, an increased direct or indirect exposure potential may exist.

Based on the low potential for direct and indirect exposure of the general population under the industrial uses identified in this submission, the substance is not likely to pose a significant health risk to the general population, and is therefore unlikely to be harmful to human health.

However, based on the current understanding of carbon nanotubes and of nanomaterials in general, the risk arising from the use of the substance in consumer products is not known at this time.  The use of the substance in consumer products or in products intended for use by or for children may significantly alter the exposure of the general population resulting in the substance becoming harmful to human health.  Similarly, the import or manufacture of the substance in quantities greater than 10 000 kg/yr may significantly increase the exposure levels of the general population resulting in the substance becoming harmful to human health.  Consequently, more information is necessary to better characterize potential health risks.

I would like to see a definition for the word short as applied, in this risk assessment, to multi-walled carbon nanotubes. That said, this assessment is pretty much in line with current thinking about short, multi-walled carbon nanotubes. In short (wordplay noted), these carbon nanotubes are relatively safe (although some toxicological issues have been noted) as far as can be determined. However, the ‘relatively safe’ assessment may change as more of these carbon nanotubes enter the environment and as people are introduced to more products containing them.

One last comment, I find it surprising I can’t find any mention in the risk assessment of emergency situations such as fire, earthquake, explosions, etc. which could conceivably release short multi-walled carbon nanotubes into the air exposing emergency workers and people caught in a disaster. As well, those airborne materials might subsequently be found in greater quantity in the soil and water.

Lung injury, carbon nanotubes, and aluminum oxide

It’s pretty much undisputed that long, multi-walled carbon nanotubes (MWCNTs) are likely to present a serious health hazard given their resemblance to asbestos fibres. It’s a matter of some concern that has resulted in a US National Institute of Occupational Safety and Health (NIOSH) recommendation for workplace exposure to all carbon nanotubes that is stringent. (My April 26, 2013 posting features the recommendation.)

Some recent research from North Carolina State University (NCSU) suggests that there may be a way to make long, multi-walled carbon nanotubes safer. From an Oct. 3, 2014 news item on Nanowerk,

A new study from North Carolina State University and the National Institute of Environmental Health Sciences (NIEHS) finds that coating multiwalled carbon nanotubes (CNTs) with aluminum oxide reduces the risk of lung scarring, or pulmonary fibrosis, in mice.

“This could be an important finding in the larger field of work that aims to predict and prevent future diseases associated with engineered nanomaterials,” says James Bonner, a professor of environmental and molecular toxicology at NC State …

An Oct. 3, 2014 NCSU news release, which originated the news item, describes the research in a little more detail,

Multiwalled CNTs have a wide array of applications, ranging from sporting goods to electronic devices. And while these materials have not been associated with adverse health effects in humans, research has found that multi-walled CNTs can cause pulmonary fibrosis and lung inflammation in animal models.

“Because multiwalled CNTs are increasingly used in a wide variety of products, it seems likely that humans will be exposed to them at some point,” Bonner says. “That means it’s important for us to understand these materials and the potential risk they pose to human health. The more we know, the better we’ll be able to engineer safer materials.”

For this study, the researchers used atomic layer deposition to coat multiwalled CNTs with a thin film of aluminum oxide and exposed mice to a single dose of the CNTs, via inhalation.

The researchers found that CNTs coated with aluminum oxide were significantly less likely to cause pulmonary fibrosis in mice. However, the coating of aluminum oxide did not prevent lung inflammation.

“The aluminum oxide coating doesn’t eliminate health risks related to multi-walled CNTs,” Bonner says, “but it does lower them.”

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

Atomic Layer Deposition Coating of Carbon Nanotubes with Aluminum Oxide Alters Pro-Fibrogenic Cytokine Expression by Human Mononuclear Phagocytes In Vitro and Reduces Lung Fibrosis in Mice In Vivo by Alexia J. Taylor, Christina D. McClure, Kelly A. Shipkowski, Elizabeth A. Thompson, Salik Hussain, Stavros Garantziotis, Gregory N. Parsons, and James C. Bonner. Published: September 12, 2014 DOI: 10.1371/journal.pone.0106870

This is an open access article.

The researchers offered this conclusion (part of the paper’s abstract),

These findings indicate that ALD [atomic layer deposition] thin film coating of MWCNTs with Al2O3 reduces fibrosis in mice and that in vitro phagocyte expression of IL-6, TNF-α, and OPN, but not IL-1β, predict MWCNT-induced fibrosis in the lungs of mice in vivo.

However, what I found most striking was this from the paper’s Discussion (section),

While the Al2O3 coating on MWCNTs appears to be the major factor that alters cytokine production in THP-1 and PBMCs in vitro, nanotube length is still likely an important determinant of the inflammatory and fibroproliferative effects of MWCNTs in the lung in vivo. In general, long asbestos fibers or rigid MWCNTs (i.e., >20 µm) remain in the lung and are much more persistent than shorter fibers or nanotubes [20]. Therefore, the nanotube fragments resulting from breakage of A-MWCNTs coated with 50 or 100 ALD cycles of Al2O3 would likely be cleared from the lungs more rapidly than uncoated long MWCNTs or those coated with only 10 ALD cycles of Al2O3. We observed that the fracturing of A-MWCNTs occurred only after sonication prior to administration to cells in vitro or mice in vivo. However, unsonicated A-MWCNTs could be more likely to fracture over time in tissues as compared to U-MWCNTs [uncoated]. We did not address the issue of A-MWCNT clearance before or after fracturing in the present study, but future work should focus the relative clearance rates from the lungs of mice exposed to A-MWCNTs in comparison to U-MWCNTs. Another potentially important consideration is whether or not ALD coating with Al2O3 alters the formation of a protein corona around MWCNTs. It is possible that differences in cytokine levels in the supernatants from cells treated with U- or A-MWCNTs could be due to differences in protein corona formation around functionalized MWCNTs that could modify the adsorptive capacity of the nanomaterial. Characterization of the protein corona and the adsorptive capacity for cytokines after ALD modification of MWCNTs should be another important focus for future work. [emphases mine]

In other words, researchers think coating long, MWCNTs with a certain type of aluminum might be safer due to its effect on various proteins and because coated MWCNTs are likely to fracture into smaller pieces and we know that short MWCNTs don’t seem to present a problem when inhaled.

Of course, there’s the research from Duke University (my Oct. 3, 2014 post) which suggests CNTs could present a different set of problems over time as they accumulate in the environment.

Super-black nanotechnology, space exploration, and carbon nanotubes grown by atomic layer deposition (ALD)

Super-black in this context means that very little light is reflected by the carbon nanotubes that a team at the US National Aeronautics and Space Administration (NASA) have produced. From a July 17, 2013 NASA news release (also here on EurekAlert),

A NASA engineer has achieved yet another milestone in his quest to advance an emerging super-black nanotechnology that promises to make spacecraft instruments more sensitive without enlarging their size.

A team led by John Hagopian, an optics engineer at NASA’s Goddard Space Flight Center in Greenbelt, Md., has demonstrated that it can grow a uniform layer of carbon nanotubes through the use of another emerging technology called atomic layer deposition or ALD. The marriage of the two technologies now means that NASA can grow nanotubes on three-dimensional components, such as complex baffles and tubes commonly used in optical instruments.

“The significance of this is that we have new tools that can make NASA instruments more sensitive without making our telescopes bigger and bigger,” Hagopian said. “This demonstrates the power of nanoscale technology, which is particularly applicable to a new class of less-expensive tiny satellites called Cubesats that NASA is developing to reduce the cost of space missions.”

(It’s the first time I’ve seen atomic layer deposition (ALD) described as an emerging technology; I’ve always thought of it as well established.)  Here’s a 2010 NASA video, which  provides a good explanation of this team’s work,

With the basic problem being less data due to light reflection from the instruments used to make the observations in space, the researchers determined that ALD might provide carbon nanotubes suitable for super-black instrumentation for space exploration. From the NASA news release,

To determine the viability of using ALD to create the catalyst layer, while Dwivedi [NASA Goddard co-investigator Vivek Dwivedi, University of Maryland] was building his new ALD reactor, Hagopian engaged through the Science Exchange the services of the Melbourne Centre for Nanofabrication (MCN), Australia’s largest nanofabrication research center. The Science Exchange is an online community marketplace where scientific service providers can offer their services. The NASA team delivered a number of components, including an intricately shaped occulter used in a new NASA-developed instrument for observing planets around other stars.

Through this collaboration, the Australian team fine-tuned the recipe for laying down the catalyst layer — in other words, the precise instructions detailing the type of precursor gas, the reactor temperature and pressure needed to deposit a uniform foundation. “The iron films that we deposited initially were not as uniform as other coatings we have worked with, so we needed a methodical development process to achieve the outcomes that NASA needed for the next step,” said Lachlan Hyde, MCN’s expert in ALD.

The Australian team succeeded, Hagopian said. “We have successfully grown carbon nanotubes on the samples we provided to MCN and they demonstrate properties very similar to those we’ve grown using other techniques for applying the catalyst layer. This has really opened up the possibilities for us. Our goal of ultimately applying a carbon-nanotube coating to complex instrument parts is nearly realized.”

For anyone who’d like a little more information about the Science Exchange, I posted about this scientific markeplace both on Sept. 2, 2011 after it was launched in August of that year and later on Dec. 19, 2011 in a followup about a specific nano project.

Getting back to super-black nanotechnology, here’s what the NASA team produced, from the news release,

During the research, Hagopian tuned the nano-based super-black material, making it ideal for this application, absorbing on average more than 99 percent of the ultraviolet, visible, infrared and far-infrared light that strikes it — a never-before-achieved milestone that now promises to open new frontiers in scientific discovery. The material consists of a thin coating of multi-walled carbon nanotubes about 10,000 times thinner than a strand of human hair.

Once a laboratory novelty grown only on silicon, the NASA team now grows these forests of vertical carbon tubes on commonly used spacecraft materials, such as titanium, copper and stainless steel. Tiny gaps between the tubes collect and trap light, while the carbon absorbs the photons, preventing them from reflecting off surfaces. Because only a small fraction of light reflects off the coating, the human eye and sensitive detectors see the material as black.

Before growing this forest of nanotubes on instrument parts, however, materials scientists must first deposit a highly uniform foundation or catalyst layer of iron oxide that supports the nanotube growth. For ALD, technicians do this by placing a component or some other substrate material inside a reactor chamber and sequentially pulsing different types of gases to create an ultra-thin film whose layers are literally no thicker than a single atom. Once applied, scientists then are ready to actually grow the carbon nanotubes. They place the component in another oven and heat the part to about 1,832  F (750 C). While it heats, the component is bathed in carbon-containing feedstock gas.

Congratulations to the team, I gather they’ve been working on this light absorption project for quite a while.

What do you do with a problem like regulating nanotechnology risks?

You get points for recognizing the “Sound of Music’ reference. Of course, the points aren’t useful for anything, which leads me in a roundabout way to Michael Berger’s fascinating May 28, 2013 Nanowerk Spotlight article, Does the EU’s chemical regulation sufficiently address nanotechnology risks? It’s a digest of a discussion, published in Nature Nanotechnology’s May 2013 issue, about nanotechnology regulations in light of the European Commission’s (EC; a unit in the European Union structure) Second Regulatory Review on Nanomaterials.

Berger summarizes Steffen Foss Hansen’s The European Union’s chemical legislation needs revision (article is behind a paywall) and Antonio Tajani’s response to Hansen, Substance identification of nanomaterials not key to ensuring their safe use (article is behind a paywall; Note: Links have been removed from the following excerpt),

The European Union’s chemical legislation known as REACH needs revision argues Steffen Foss Hansen, Associate Professor at DTU Environment, Technical University of Denmark. In a correspondence to the Editor of Nature Nanotechnology (“The European Union’s chemical legislation needs revision”), Hansen argues that REACH needs to be revised in three major areas.

First of all, a distinction needs to be made in the legal text of REACH between the bulk and the nano form of a given material and Hansen argues that the European Commission should acknowledge that nanomaterials cannot be identified solely by chemical composition. Additional main identifiers (such as primary particle size distribution, shape – including aspect ratio – specific surface area and surface treatment) are needed as this is the only manner in which it can be made clear that the properties and behavior of nanomaterials differ fundamentally from each other and from the bulk material.

In a response to Hansen’s Correspondence, Antonio Tajani, Vice-President of the European Commission and Commissioner for Industry and Entrepreneurship, writes that substance identification of nanomaterials is not key to ensuring their safe use (“Substance identification of nanomaterials not key to ensuring their safe use”).

Tajani argues that substance identification is only one element and that trying to identify unambiguous rules for substance identification is probably elusive and might result in ever more complex rules on what is considered as the same substance as opposed to different substances, without necessarily resulting in more safety of nanomaterials. Instead, Tajani and the European Commission wish to focus on clarifying what is needed to demonstrate the safe use while also noting that the implementation of regulatory changes would take several years and hence is not desirable.

As per my Oct. 25, 2011 posting (Nanoparticle size doesn’t matter), my thinking on environmental, health, and safety issues regarding engineered nanomaterials has been in the process of change and I note that focusing on the size, shape, and other factors would make regulation next to impossible. So, I’m inclined to agree with Tajani’s arguments that trying to develop “unambiguous rules for substance identification” is not a worthwhile approach to dealing with any EHS issues that nanomaterials may present and will likely prove futile in the same way as gaining points for recognizing my attempted ‘Sound of Music’ reference.

I assume that Tajani and Hansen are referring to engineered nanomaterials as opposed to naturally occurring nanomaterials. (I too forget to specify but unless otherwise noted I’m usually referring to engineered nanomaterials.)

For me, two of the most compelling issues that Hansen presents revolve around a lack of data and standardized testing (from Hansen’s article in Nature),

… there are few measured exposure data and that few environmental fate and behaviour studies are available. …

… there are currently no standardized (eco)toxicity test guidelines in use …

I do wonder how many the word ‘few’ represents as I’m reminded of the plethora of studies on silver nanoparticles and on long, multi-walled carbon nanotubes. Certainly, they are attempting to address the situation regarding consistent testing protocols in the US as per my May 8, 2013 post about the NanoGo Consortium. Perhaps the EC folks could consider using these protocols as a model for a European version?  I assume that Hansen is commenting on a broader, European-inflected picture rather than the piecemeal, ‘globalish’ picture I have formed from my meanderings in the nanosphere.

Hansen also points this out in his Nature article (Note: Footnotes have been removed),

Another disturbing aspect of the Second Regulatory Review on Nanomaterials is that it focuses only on first-generation nanomaterials (that is, passive nanostructures such as nanoparticles). The Staff Working Paper acknowledges that second- and third-generation nanomaterials (for example, targeted drug-delivery systems and novel robotic devices) are entering early stages of market development, …

I’m beginning to find the discussion about definitions and resultant regulations wearing and am coming to the conclusion that the focus should be on bringing the information already gathered together, standardizing tests, determining what is  known and not known, and establishing some forward momentum.

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

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.

Multi-walled carbon nanotubes, cancer, and the US National Institute of Occupational Health and Safety’s (NIOSH) latest findings

A Mar. 11, 2013 news item on Nanowerk reveals some of the latest research performed by US National Institute of Occupational Health Safety (NIOSH) researchers into the question of whether or not multi-walled carbon nanotubes (MWCNT) cause cancer,

Earlier today, at the annual meeting of the Society of Toxicology, NIOSH researchers reported preliminary findings from a new laboratory study in which mice were exposed by inhalation to multi-walled carbon nanotubes (MWCNT). The study was designed to investigate whether these tiny particles have potential to initiate or promote cancer. By “initiate,” we mean the ability of a substance to cause mutations in DNA that can lead to tumors. By “promote,” we mean the ability of a substance to cause cells that have already sustained such DNA mutations to then become tumors.

It is very important to have new data that describe the potential health hazards that these materials might represent, so that protective measures can be developed to ensure the safe advancement of nanotechnology in the many industries where it is being applied.

The Mar. 11, 2013 posting (which originated the news item) by Vincent Castranova, PhD; Charles L Geraci, PhD; Paul Schulte, PhD  on the NIOSH blog provides details about the experimental protocols and the outcome of the experiments,

In the NIOSH study, a group of laboratory mice were injected with a chemical that is a known cancer initiator, methylcholanthrene.  Another group of mice were injected with a saline solution as a control group.  The mice then were exposed by inhalation either to air or to a concentration of MWCNT.   These protocols enabled the researchers to investigate whether MWNCT alone would initiate cancer in mice, or whether MWCNT would promote cancer where the initiator, methylcholanthrene, had already been applied.

Mice receiving both the initiator chemical plus exposure to MWCNT were significantly more likely to develop tumors (90% incidence) and have more tumors (an average of 3.3 tumors/mouse lung) than mice receiving the initiator chemical alone (50% of mice developing tumors with an average of 1.4 tumors/lung).  Additionally, mice exposed to MWCNT and to MWCNT plus the initiator chemical had larger tumors than the respective control groups.  The number of tumors per animal exposed to MWCNT alone was not significantly elevated compared with the number per animal in the controls.  These results indicate that MWCNT can increase the risk of cancer in mice exposed to a known carcinogen.  The study does not suggest that MWCNTs alone cause cancer in mice.

That last sentence is quite important because (from the NIOSH blog post),

Several earlier studies in the scientific literature indicated that MWCNT could have the potential to initiate or promote cancer. The new NIOSH study is the first to show that MWCNT is a cancer promoter in a laboratory experiment, and reports the growth of lung tumors in laboratory mice following inhalation exposure to MWCNT rather than injection, instillation, or aspiration.  Inhalation exposure most closely resembles the exposure route of greatest concern in the workplace. In the study, laboratory mice were exposed to one type of MWCNT through inhalation at a concentration of 5 milligrams per cubic meter of air for five hours per day for a period of 15 days.

Risk of occupational cancer depends on the potency of a given substance to cause or promote cancer and the concentration and duration of worker exposure to that substance.  This research is an important step in our understanding of the hazard associated with MWCNT, but before we can determine whether MWCNT pose an occupational cancer risk, we need more information about actual exposure levels and the types and nature of MWCNT being used in the workplace, and how that compares to the material  used in this study.

This study is part of a larger program designed to establish safety practices with regard to handling nanomaterials/nanoparticles (from the NIOSH blog post),

These laboratory studies are part of a strategic program of NIOSH research to better understand the occupational health and safety implications of nanoparticle exposure, and to make authoritative science-based recommendations for controlling exposures so that the technology is developed responsibly as the research advances, and the societal benefits of nanotechnology can be realized.  NIOSH has worked closely with diverse public and private sector partners over the past decade to incorporate occupational health and safety into practical strategies for safe development of this revolutionary technology. More information is available on the NIOSH nanotechnology topic page.

There is no mention in the blog post as to whether the MWCNTs in this latest work were long or short or a mixture of both. Unfortunately, the study has not yet been published in a journal, so it’s not yet available for reading purposes. I did mention carbon nanotubes and toxicity in a Jan. 16, 2013 posting about a recent study,

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.

While I find this latest work from NIOSH interesting, it’s hard for me to understand why there’s no mention of length. Unless, the NIOSH work is focused on what happens when MWCNTs are inhaled along with known cancer initiators and they believe that length is not a factor.

ETA Mar. 15, 2013: I did find get some information about the length (long carbon nanotubes for the most part) as per this Mar. 14, 2013 posting or you can find the update in my Mar. 15, 2013 posting here.

Natural and engineered nanoparticles in an Orion magazine podcast & in a NanoBosc machinima piece

The Jan. 16, 2013 Orion magazine podcast discussion (more about that later) regarding safety and engineered and natural nanoparticles arose from an article (worth reading) by Heather Millar in the magazine’s January/February 2013 issue, Pandora’s Boxes.

For anyone familiar with the term ‘Pandora’s box’, Millar’s and the magazine’s bias is made clear immediately, nanoparticles are small and threatening. From the Pandora’s box Wikipedia essay,

Today, the phrase “to open Pandora’s box” means to perform an action that may seem small or innocuous, but that turns out to have severe and far-reaching consequences. [emphases mine]

Millar’s article is well written and offers some excellent explanations. For example, there’s this from Pandora’s Boxes,

So chemistry and physics work differently if you’re a nanoparticle. You’re not as small as an atom or a molecule, but you’re also not even as big as a cell, so you’re definitely not of the macro world either. You exist in an undiscovered country somewhere between the molecular and the macroscopic. Here, the laws of the very small (quantum mechanics) merge quirkily with the laws of the very large (classical physics). Some say nanomaterials bring a third dimension to chemistry’s periodic table, because at the nano scale, long-established rules and groupings don’t necessarily hold up.

Then, she has some dodgier material,

Yet size seems to be a double-edged sword in the nanoverse. Because nanoparticles are so small, they can slip past the body’s various barriers: skin, the blood-brain barrier, the lining of the gut and airways. Once inside, these tiny particles can bind to many things. They seem to build up over time, especially in the brain. Some cause inflammation and cell damage. Preliminary research shows this can harm the organs of lab animals, though the results of some of these studies are a matter of debate.

Some published research has shown that inhaled nanoparticles actually become more toxic as they get smaller. Nano–titanium dioxide, one of the most commonly used nanoparticles (Pop-Tarts, sunblock), has been shown to damage DNA in animals and prematurely corrode metals. Carbon nanotubes seem to penetrate lungs even more deeply than asbestos. [emphases mine]

I think it’s worth ‘unpacking’ these two paragraphs, so here goes.  Slipping past the body’s barriers is a lot more difficult than Millar suggests in the first paragraph. My July 4, 2012 posting on breakthough research  where they penetrated the skin barrier includes this comment from me,

After all the concerns  about nanosunscreens and nanoparticles penetrating the skin raised by civil society groups, the Friends of the Earth in particular, it’s interesting to note that doctors and scientists consider penetration of the skin barrier to be extremely difficult. Of course, they seem to have solved [as of July 2012] that problem which means the chorus of concerns may rise to new heights.

I had a followup in my Oct.3, 2012 posting titled, Can nanoparticles pass through the skin or not?, suggesting there’s still a lot of confusion about this topic even within the scientific community.

Moving on to the other ‘breaches’. As I recall, there was a recent  (Autumn 2012?) nanomedicine research announcement that the blood-brain barrier was breached by nanoparticles. I haven’t yet encountered any mention of breaching the gut and I mention lungs in my next paragraph where I discuss carbon nanotubes.

As for that second paragraph, it’s an example of scaremongering. ‘Inhaled nanoparticles become more toxic as their size decreases’—ok. Why mention nano-titanium oxide in pop tarts and sunblocks, which are not inhaled, in the followup sentence? As for the reference to DNA damage and corroded metals further on, this is straight out of the Friends of the Earth literature which often cites research in a misleading fashion including those two pieces.  There is research supporting part of Millar’s statement about carbon nanotubes—provided they are long and multiwalled. In fact, as they get shorter, the resemblance to asbestos fibers in the lungs or elsewhere seems to disappear as per my Aug 22, 2012 posting and my Jan. 16, 2013 posting.

You don’t need to read the article before listening to the fascinating Jan. 16, 2013 Orion magazine podcast with Millar (reading portions of her article) and expert guests, Mark Wiesner from Duke University and director of their Center for Environmental Implications of Nano Technology (CEINT was first mentioned in my April 15, 2011 posting), Ronald Sandler from Northeastern University and author of Nanotechnology: The Social And Ethical Issues, and Jaydee Hanson, policy director for the International Center for Technology Assessment.

The discussion between Wiesner, Sandler, and Hanson about engineered and natural nanoparticles is why I’ve called the podcast fascinating. Hearing these experts ‘fence’ with each other highlights the complexities and subtleties inherent in discussions about emerging technologies (nano or other) and risk. Millar did not participate in that aspect of the conversation and I imagine that’s due to the fact that she has only been researching this area for six months while the other speakers all have several years worth experience individually and, I suspect, may have debated each other previously.

At the risk of enthusing too much about naturally occurring nanoparticles, I’m mentioning, again (my Feb. 1, 2013 posting), the recently published book by Nanowiki, Nanoparticles Before Nanotechnology, in the context of the stunning visual images used to illustrate the book. I commented previously about them and Victor Puntes of the Inorganic Nanoparticles Group at the Catalan Institute of Nanotechnology (ICN) and one of the creators of this imagery, kindly directed me to a machinima piece (derived from the NanoBosc Second Life community) which is the source for the imagery. Here it is,

NanoBosc from Per4mance MetaLES ..O.. on Vimeo.

Happy Weekend!

Canada-US Regulatory Cooperation Council’s Nanotechnology Work Plan

Thanks for Lynn L. Bergeson for her Dec. 1, 2012 posting on the Nanotechnology Now website for the information about a Nov. 28, 2012 webinar that was held to discuss a Nanotechnology Work Plan developed by the joint Canada-US Regulatory Cooperation Council (or sometimes it’s called the US-Canada Regulatory Cooperation Council),

The RCC requested that industry provide more information on the commercial distribution of nanomaterials, as well as more transparency by claiming confidentiality of only that information absolutely critical to market advantage.

To compare risk assessment and risk management practices to highlight and identify best practices, data gaps, and differences between the two jurisdictions, the RCC sought nominations of a nanomaterial substance for a case study. Four nanomaterial substances were nominated: multiwall carbon nanotubes, nanocrystalline cellulose, nano silver, and titanium dioxide. The RCC has selected multiwall carbon nanotubes for the case study. The RCC intends to hold in March 2013 a workshop in Washington, D.C., to discuss information collected to date and approaches moving forward. In spring 2013, the RCC will hold one or two conference calls or webinars to discuss information gathered between countries and the path forward. Finally, in fall 2013, the RCC expects to hold a stakeholder consultation/workshop on results to date.

Here’s some background on the RCC. First announced in February 2011, the RCC had its first ‘stakeholder’ session (attended by approximately 240)  in January 2012 in Washington, DC. where a series of initiatives, including nanotechnology, were discussed (from the US International Trade Administration RCC Stakeholder Outreach webpage),

Agriculture and Food, Session A

  • Perimeter approach to plant protection

Agriculture and Food, Session B

  • Crop protection products

Agriculture and Food, Session C

  • Meat/poultry – equivalency
  • Meat/poultry – certification requirements
  • Meat cut nomenclature

Agriculture and Food, Session D

  • Veterinary drugs
  • Zoning for foreign animal disease

Agriculture and Food, Session E

  • Financial protection to produce sellers

Agriculture and Food, Session F

  • Food safety – common approach
  • Food safety – testing

Road Transport – Motor Vehicles

  • Existing motor vehicle safety standards
  • New motor vehicle safety standards

Air Transport

  • Unmanned aircraft


  • Intelligent Transportation Systems


  • Dangerous goods means of transportation

Marine Transport

  • Safety and security framework & arrangement for the St. Lawrence Seaway & Great Lakes System
  • Marine transportation security regulations
  • Recreational boat manufacturing standards
  • Standard for lifejackets

Rail Transport

  • Locomotive Emissions
  • Rail Safety Standards


  • Emission standards for light-duty vehicles

Personal Care Products & Pharmaceuticals

  • Electronic submission gateway
  • Over-the-counter products – common monographs
  • Good manufacturing practices

Occupational Safety Issues

  • Classification & labelling of workplace hazardous chemicals


  • Nanotechnology

Led jointly by senior officials from Canada and the United States, the purpose of the various technical review sessions was to seek expert advice and technical input from the approximately 240 stakeholders in attendance.

Since the Jan. 2012 meeting, a Nanotechnology Work Plan has been developed and that’s what was recently discussed at the Nov. 28, 2012 webinar. I did find more on a Canadian government website, Canada’s Economic Action Plan Nanotechnology Work Plan webpage,

Nanotechnology Work Plan

 Canada Leads: Karen Dodds, Assistant Deputy Minister, Science and Technology Branch, Environment Canada (EC)

Hilary Geller, Assistant Deputy Minister, Healthy Environments and Consumer Safety Branch, Health Canada (HC)

U.S. Lead: Margaret Malanoski, Office of Information and Regulatory Affairs, Office of Management and Budget

Deliverable Outcome: Share information and develop common approaches, to the extent possible, on foundational regulatory elements, including criteria for determining characteristics of concern/no concern, information gathering, approaches to risk assessment and management, etc. Develop joint initiatives to align regulatory approaches in specific areas such that consistency exists for consumers and industry in Canada and the US.

Principles: Identification of common principles for the regulation of nanomaterials to help ensure consistency for industry and consumers in both countries

3-6 months:

Canada provides initial feedback on US “Policy Principles for the US Decision-Making Concerning Regulation and Oversight of Applications of Nanotechnology and Nanomaterials”.

6-12 months:

Countries complete an initial draft of shared principles for the regulation of nanomaterials.

12-18 months:

Update of draft principles informed from on-going stakeholder and expert consultations.

18th month:

Stakeholder consultation / workshop on results to date and future ongoing engagement.

Beyond 18 months:

Countries complete final draft of shared principles for the regulation of nanomaterials.

Workplan for Industrial Nanomaterials

Priority-Setting: Identify common criteria for determining characteristics of industrial nanomaterials of concern/no-concern

1-3 months:

  1. Define and finalize workplan (1st month)
  2. Develop mechanisms for stakeholder outreach and engagement (1st month)
  3. Conference call with relevant stakeholders to share and discuss workplan and call for Industry to volunteer nanomaterials for joint CAN/US review

3-6 months:

Share available scientific evidence regarding characteristics of industrial nanomaterials including that obtained from existing international fora (e.g. OECD Working Party on Manufactured Nanomaterials [Canada is a lead in the OECD Working Party on Manufactured Nanomaterials]).

8th month:

Stakeholder workshop to discuss information collected to date and approaches moving forward.

6-12 months:

Initiate an analysis of characteristics of select nanomaterials: similarities, differences, reasons for them.

Initiate discussions on approaches to consider for common definitions and terminology.

12th month:

Second conference call with relevant stakeholders to discuss non-CBI information gathered between the Countries and to discuss path forward in terms of development of reports and analyses.

12-18 months:

Develop draft criteria for determining characteristics of industrial nanomaterials of concern/no-concern.

15th month:

Third conference call with relevant stakeholders to discuss progress and to prepare for the upcoming stakeholder consultation/workshop.

Here’s information for the leads should you feel compelled to make contact,


(Lead) Karen Dodds, Assistant Deputy Minister, Science and Technology, Environment Canada ([email protected]; ph. 613- 819-934-6851)

Hilary Geller, Assistant Deputy Minister, Healthy Environments and Consumer Safety Branch ([email protected]; ph. 613-946-6701)

United States

(Lead) Margaret Malanoski, Office of Management and Budget ([email protected])

I gather that the ‘stakeholders’ are business people, researchers, and policy analysts/makers as there doesn’t seem to be any mechanism for public consultation or education, for that matter.

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

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.