Tag Archives: US National Institute of Occupational Health and Safety

Happy (belated) US National Nanotechnology Day (October 9, 2022)

Leave a reply

H/t to Lynn L. Bergeson’s and Carla N. Hutton’s October 8, 2022 posting on The National Law Review website for the news about the US National Nanotechnology Day on October 9, 2022.

Here’s more from the US National Institute of Occupational Safety and Health (NIOSH) October 6, 2022 posting by Adrienne Eastlake, Gary Roth, and Nicole Neu-Baker on the NIOSH Science blog (Note: Links and footnotes have been removed),

Every year on October 9th we celebrate National Nanotechnology Day. The date 10-9 pays homage to the nanometer scale: 10–9 (one billionth of a meter). Anything that can be measured in nanometers is extremely small! For instance, the width of a strand of human hair is about 90,000 nanometers, bacteria are between 300–5,000 nanometers, viruses are 5–300 nanometers, the diameter of deoxyribonucleic acid (DNA) is 2.5 nanometers, and a single atom is 0.1–0.5 nanometers. A healthy young adult’s fingernail grows an average of just over 1 nanometer per second (3.47 millimeters per month on average)!1 National Nanotechnology Day was created to help raise awareness of nanotechnology, to show how it is currently used in products that enrich our daily lives and to consider future challenges and opportunities.

…

Engineered nanomaterials (ENMs) are materials intentionally produced to have particle sizes between 1 and 100 nanometers in at least one dimension. These materials can be nanoparticles, nanotubes, or nanoplates, depending on their shape. ENMs typically have new or unique properties different from those of larger forms of the same material, making them desirable for specific product applications. These properties can contribute to increased elasticity, tensile strength, electrical conduction, and reactivity. Increasingly, they are added into existing materials to give these properties to bulk materials (such as plastics or metals). Consumer products using ENMs include cosmetics, sunscreen, food storage products, appliances, clothing, electronics, computers, sporting goods, and coatings. ENMs are also used in state-of-the-art sensors and biomedical technologies. COVID-19 research and the development of vaccines depend heavily on nanotechnology, and many vaccines use nanotechnology to improve their effectiveness. You probably are interacting with nanotechnology-enabled products every day!

…

Since the early 2000s, NIOSH has been at the forefront of efforts to characterize potential workplace hazards for those working with ENMs and to ensure safe and healthy workplaces, including the creation of the NIOSH Nanotechnology Research Center in 2004. Since then, NIOSH has published a quantitative risk assessment and an elemental mass-based recommended exposure limit (REL) for each of the following: carbon nanotubes/nanofibers,4 nanoscale titanium dioxide, 5 and silver nanomaterials.6 In addition, the poster Controlling Health Hazards When Working With Nanomaterials: Questions to Ask Before You Start is a helpful and easy-to-use visual resource for the workplace.

…

In collaboration with RTI International, NIOSH administered a survey developed by the RAND Corporation to North American companies working with nanomaterials to assess health and safety practices and the impact of efforts made by NIOSH to protect worker health and safety.9 Forty-five companies in the United States and Canada that fabricate, manufacture, handle, dispose, or otherwise use nanomaterials completed the online survey in 2019. The survey included research questions about nanomaterials in use and the overall occupational health and safety culture at the companies. Additionally, other questions asked about whether the companies interacted with NIOSH or used NIOSH resources to inform their health and safety practices and policies. More than a third (37.8%) of the 45 respondents reported using at least one NIOSH resource for information about safe handling of nanomaterials. Larger companies were more likely to report using NIOSH resources than companies employing fewer than 50 employees. While the survey was limited by the small sample size, it provided valuable insight, including that future NIOSH outreach should specifically target small businesses that use or handle nanomaterials.

We hope you find a way to celebrate National Nanotechnology Day! The National Nanotechnology Initiative (nano.gov) suggests running a 100 Billion Nanometer Dash. Sounds like quite a distance, but it is just 100 meters (328 feet) or 6.2% of a mile. As we continue to provide guidance and recommendations to keep workers safe when working with ENMs, we will be right there with you until you cross the finish line… one nanometer at a time. Good luck!

You can find other activities to celebrate the day (even belatedly) at nano.gov here on their National Nanotechnology Day webpage.

US National Institute of Occupational Health and Safety (NIOSH) released four new documents for handling nanomaterials

Leave a reply

A March 12, 2018 news item on Nanowerk announced the latest from the US National Institute of Occupational Health and Safety (NIOSH) on the safe handling of nanomaterials in the workplace,

Realizing the promise of any scientific advancement requires understanding of its potential human health effects, and its safe and responsible development, even at the level of engineered nanomaterials, which can be nearly atomic-sized. The National Institute for Occupational Safety and Health (NIOSH) launched four new products this week intended to provide options to companies for controlling possible exposure of their workers to nanomaterials on the job.

A March 12, 2018 NIOSH news release, which originated the news item, fills in some details,

Engineered nanomaterials are intentionally produced to have at least one primary dimension less than 100 nanometers (nm). These very small particles have unique shapes and physical and chemical properties. These materials become desirable for specific product applications in areas including medicine, electronics, biomaterials, and consumer products. Workers in industries that use or make these uniquely engineered nanomaterials may inhale nanoparticles on a daily basis, posing a potential respiratory hazard.

“Researching, developing, and utilizing these nano properties is at the heart of new technology, just as worker safety is at the heart of what we do at NIOSH,” said NIOSH Director John Howard, M.D. “The information contained in these new workplace design solution documents provide employers with strategic steps towards making sure their employees stay safe while handling nanomaterials.”

The four new documents provide helpful recommendations on minimizing exposures during common processes and tasks, including:

Each workplace design solutions document provides key tips on the design, use, and maintenance of exposure controls for nanomaterial production, post processing, and use. The poster poses questions that employers and workers should consider before starting work with a nanomaterial. For each question, the poster provides options to reduce exposures to nanomaterials based on the physical form. The poster can be displayed in a lab or work environment, making it an easily accessible reminder of the important health and safety considerations for working with nanomaterials.

To access the products, and for more information about nanotechnology research at NIOSH, please visit https://www.cdc.gov/niosh/topics/nanotech/pubs.html

NIOSH is the federal institute that conducts research and makes recommendations for preventing work-related injuries and illnesses. More information about NIOSH can be found at www.cdc.gov/niosh.

That’s all folks!

US National Insitute for Occupational Health and Safety issues report on strategies for handling nanomaterials

Leave a reply

A Dec. 19, 2013 news item on Nanowerk announces the release of a recent publication about the safe handling of nanomaterials from the US National Institute of Occupational Health and Safety (NIOSH), Note: A link has been removed,

Occupational health risks associated with manufacturing and using nanomaterials are not yet clearly understood. However, initial toxicological data indicate that there is reason for caution. NIOSH is committed to promoting the responsible development and advancement of nanotechnology through its research and communication efforts to protect workers. NIOSH has taken a leading role in conducting research and making recommendations for nanotechnology safety in work settings. See the nanotechnology topic page for a list of documents and resources.

Recently, NIOSH has released a document titled, Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes, which provides information on how to control exposures for many of the most common processes seen in facilities that use or produce nanomaterials or nano-enabled products.

A Nov.8, 2013 NIOSH news release provides some additional insight into NIOSH’s strategy,,

Engineering controls are favored over administrative controls and personal protective equipment for lowering worker exposures, because they are designed to remove the hazard at the source, before it comes into contact with the worker. However, evidence showing the effectiveness of controls during the manufacture and downstream use of engineered nanomaterials in specific applications has been scarce.

The NIOSH recommendations fill a gap for science-based guidance that employers and workers can apply now, as research continues for better understanding of nanomaterial characteristics, and ways in which workers may be exposed, that may pose the risk of adverse health effects.

The consumer products market currently has more than 1,000 nanomaterial-containing products including makeup, sunscreen, food storage products, appliances, clothing, electronics, computers, sporting goods, and coatings. As more nanomaterials are introduced into the workplace and nano-enabled products enter the market, it is essential that producers and users of engineered nanomaterials ensure a safe and healthy work environment, the new document states.

Processes discussed in the document and for which controls are recommended and described include reactor operations and cleanout processes, small-scale weighing and handling of nanopowders, intermediate and finishing processes, and maintenance tasks. The document also includes recommendations for evaluating the performance of control technologies and control systems.

There’s a Dec. 9, 2013 NIOSH blog posting written by Jennifer L. Topmiller and Kevin H. Dunn which provides more detail about workers’ exposure to nanomaterials,,

Engineered nanomaterials are materials that are intentionally produced and have at least one primary dimension less than 100 nanometers (nm). Nanomaterials have properties different from those of larger particles of the same material, making them unique and desirable for specific product applications.  The consumer products market currently has more than 1,000 nanomaterial-containing products including makeup, sunscreen, food storage products, appliances, clothing, electronics, computers, sporting goods, and coatings [WWICS 2011].

It is difficult to estimate how many workers are involved in this field. By one estimate, there are 400,000 workers worldwide in the field of nanotechnology, with an estimated 150,000 of those in the United States [Roco et al. 2010]. The National Science Foundation has estimated that approximately 6 million workers will be employed in nanotechnology industries worldwide by 2020.

Occupational health risks associated with manufacturing and using nanomaterials are not yet clearly understood.  However, initial toxicological data indicate that there is reason for caution. NIOSH is committed to promoting the responsible development and advancement of nanotechnology through its research and communication efforts to protect workers. NIOSH has taken a leading role in conducting research and making recommendations for nanotechnology safety in work settings. …

…

The greatest exposures to raw nanomaterials are likely to occur in the workplace during production, handling, secondary processing, and packaging. In a review of exposure assessments conducted at nanotechnology plants and laboratories, Dr. Derk Brouwer determined that activities which resulted in exposures included harvesting (e.g., scraping materials out of reactors), bagging, packaging, and reactor cleaning [Brouwer 2010]. Downstream activities that may release nanomaterials include bag dumping, manual transfer between processes, mixing or compounding, powder sifting, and machining of parts that contain nanomaterials.  Similar to controlling hazards in traditional macro-scale manufacturing, engineering controls are recommended to reduce exposures to nanomaterials.

… Because little has been published on exposure controls in the production and use of nanomaterials, this document focuses on applications that have relevance to the field of nanotechnology and on engineering control technologies currently used, and known to be effective, in other industries.

Assessing how well the exposure control works is also essential for verifying that the exposure goals of the facility have been successfully met. This document covers a range of control evaluation tools including airflow visualization and measurement and containment test methods, such as tracer gas testing. Additional methods, such as video exposure monitoring, also provide information on critical task-based exposures and helps identify high-exposure activities and help provide the basis for interventions.

intriguingly, there’s also a plea for partnership at the end of this Dec. 9, 2013 NIOSH posting,

Producers and users of engineered nanomaterials are invited and encouraged to partner with NIOSH. Companies that have installed exposure controls, such as local exhaust ventilation, or are interested in assessing and reducing worker exposures can work with NIOSH engineers to develop and evaluate exposure mitigation options. Partnering with NIOSH not only benefits your company by providing an assessment of process emissions and recommending effective exposure control approaches  but also expands the knowledge base that benefits the industry as a whole.  Please feel free to contact us through the comment section below or by sending an e-mail to nioshblog@cdc.gov.  Thank for your interest in protecting workers!

You can find the NIOSH report, Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes here.

Gloves, Québec’s (Canada) Institut de recherche Robert-Sauvé en santé et en sécurité du travail, and a workplace nanotoxicity methodology report

Leave a reply

A new report on a workplace health and safety issue in regard to nanoparticles (Development of a Method of Measuring Nanoparticle Penetration through Protective Glove Materials under Conditions Simulating Workplace Use)  was released in June 2013 by Québec’s Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST). Little research has been done on exposure through skin (cutaneous exposure), most research has focused on exposure by inhalation according to the report (en français version here),

In the workplace, the main pathway to NP exposure is inhalation (Ostiguy et al., 2008a). Exposure by the cutaneous route has not been studied much, partly because of the widely held belief that skin offers an impermeable barrier to NPs (Truchon et al., 2008). Yet a growing number of studies have pointed to the possible percutaneous absorption of NPs, such as in the case of skin damaged by abrasion (Zhang et al., 2008), repeated flexion (Rouse et al., 2007) or even through intact skin (Ryman-Rasmussen et al., 2006). Pores, hair follicles and sweat glands may also play a role in facilitating absorption of NPs through the skin (Hervé-Bazin, 2007). The nanoparticles are then carried throughout the body by the lymphatic circulatory system (Papp et al., 2008). Induced direct toxic effects have also been reported for epidermal keratinocyte cells exposed to carbon nanotubes and other types of NPs (Shvedova, 2003). [p. 17 PDF version; p. 1 print version; Note: See report bibliography for citations]

The researchers examined gloves made of four different types of material: nitrile, latex, neoprene, and butyl rubber under a number of different conditions. One type of nanoparticle was used for the study, titanium dioxide in powder and liquid forms. The report summary provides a bit more detail about the decision to develop a methodology and the testing methods,

With the exponential growth in industrial applications of nanotechnologies and the increased risk of occupational exposure to nanomaterials, the precautionary principle has been recommended. To apply this principle, and even though personal protective equipment against nanoparticles must be considered only as a last resort in the risk control strategy, this equipment must be available. To respond to the current lack of tools and knowledge in this area, a method was developed for measuring the penetration of nanoparticles through protective glove materials under conditions simulating workplace use.

This method consists of an experimental device for exposing glove samples to nanoparticles in powder form or in colloidal solution, while at the same time subjecting them to static or dynamic mechanical stresses and conditions simulating the microclimate in the gloves. This device is connected to a data control and acquisition system. To complete the method, a sampling protocol was developed and a series of nanoparticle detection techniques was selected.

Preliminary tests were performed using this method to measure the resistance of four models of protective gloves of different thicknesses made of nitrile, latex, neoprene and butyl to the passage of commercial TiO2 nanoparticles in powder form or colloidal solution. The results seem to indicate possible penetration of the nanoparticles in some types of gloves, particularly when subjected to repeated mechanical deformation and when the nanoparticles are in the form of colloidal solutions. Additional work is necessary to confirm these results, and consideration should be given to the selection of the configurations and values of the parameters that best simulate the different possible workplace situations. Nevertheless, a recommendation can already be issued regarding the need for regular replacement of gloves that have been worn, particularly with the thinnest gloves and when there has been exposure to nanoparticles in colloidal solution.

For interested parties, here’s a citation for and a link to the report (PDF),

Development of a Method of Measuring Nanoparticle Penetration through Protective Glove Materials under Conditions Simulating Workplace Use by Dolez, Patricia; Vinches, Ludwig; Perron, Gérald; Vu-Khanh, Toan; Plamondon, Philippe; L’Espérance, Gilles; Wilkinson, Kevin; Cloutier, Yves; Dion, Chantal; Truchon, Ginette
Studies and Research Projects / Report  R-785, Montréal, IRSST, 2013, 124 pages.

I last wrote about gloves and toxicity in a June 11, 2013 posting about gloves with sensors (they turned blue when exposed to toxic levels of chemicals). It would be interesting if they could find a way to create gloves with sensors that warn you when you are reaching dangerous levels of exposure through your gloves. Of course, first they’d have to determine what constitute a dangerous level of exposure. The US National Institute of Occupational Health and Safety (NIOSH) recently released its recommendations for exposure to carbon nanofibers and carbon nanotubes (my April 26, 2013 posting). In layperson’s terms, the recommended exposure is close to zero exposure. Presumably, the decision was based on the principle of being ‘safe rather than sorry’.

One final comment about exposure to engineered nanoparticles through skin, to date there has been no proof that there has been any significant exposure via skin. In fact, the first significant breach of the skin barrier was achieved for medical research, Chad Mirkin and his team at Northwestern University trumpeted their research breakthrough (pun intended) last year, from my July 4, 2012 posting,

Researchers at Northwestern University (Illinois, US) have found a way to deliver gene regulation technology using skin moisturizers. From the July 3, 2012 news item on Science Blog,

A team led by a physician-scientist and a chemist — from the fields of dermatology and nanotechnology — is the first to demonstrate the use of commercial moisturizers to deliver gene regulation technology that has great potential for life-saving therapies for skin cancers.

The topical delivery of gene regulation technology to cells deep in the skin is extremely difficult because of the formidable defenses skin provides for the body. The Northwestern approach takes advantage of drugs consisting of novel spherical arrangements of nucleic acids. These structures, each about 1,000 times smaller than the diameter of a human hair, have the unique ability to recruit and bind to natural proteins that allow them to traverse the skin and enter cells.

This goes a long way to explaining why primary occupational health and safety research has focused on exposure via inhalation rather than skin.  That said, I think ensuring safety means minimizing exposure by all routes until more is known about the hazards.

No more carbon nanotubes from Bayer MaterialScience

Leave a reply

A May 8, 2013 news item on Nanowerk proclaims,

Bayer MaterialScience intends to focus its development activities more intently on topics that are closely linked to its core business. For that reason the company will bring its work on carbon nanotubes (CNTs) to a close. Precisely how the research results and know-how for the production and application CNT will be used further will be determined shortly.

Researchers from Bayer MaterialScience had collaborated with external partners in recent years to resolve complex issues related to the safe production of specific carbon nanotubes. [emphasis mine] Methods for scaling up the production processes were developed, as were new generations of catalysts and new types of products.

The timing for this announcement from Bayer MateriaScience is interesting given that the US National Institute of Occupational Health and Safety (NIOSH) just announced some stringent recommendations (almost zero) for occupational exposure to carbon nanofibers and carbon nanotubes (my Apr. 28, 2013 posting).

The May 8, 2013 Bayer MaterialScience news release, which originated the news item, provides more detail about the business decision,

Much of the knowledge gleaned over recent years was made available to other companies and research institutions within the Innovation Alliance Carbon Nanotubes (Inno.CNT), which counts Bayer MaterialScience among its roughly 90 members.

“We remain convinced that carbon nanotubes have huge potential,” says Patrick Thomas, Chief Executive Officer of Bayer MaterialScience. It has been found, however, that the potential areas of application that once seemed promising from a technical standpoint are currently either very fragmented or have few overlaps with the company’s core products and their application spectrum.

“For Bayer MaterialScience, groundbreaking applications for the mass market relating to our own portfolio and therefore comprehensive commercialization are not likely in the foreseeable future,” says Thomas. Nonetheless, this know-how provides an important basis for a possible later use of CNT, for example in the optimization of lithium ion batteries, Thomas says. “We are currently in contact with potential interested parties regarding the specific application of the know-how generated,” Thomas adds.

The conclusion of the nano projects has no impact on the headcount. All 30 people employed in this sector will be transferred to other suitable positions within the Group.

I”m glad to hear no one will lose their job.

Finally, I recall reading somewhere that there was a glut of carbon nanotube production and taking that with the recent NIOSH recommendation and Bayer’s claim of poor prospects for commercialization, it seems like one of those decisions that made itself.

ETA May 20, 2013: Dexter Johnson provides some insight into carbon nanotube production and the glut in his May 18, 2013 posting on Nanoclast (on the IEEE [Institute of Electrical and Electronics Engineers] website),

This [Bayer MaterialScience decision] is no surprise since there was a huge glut of product resulting in industry utilization rates that must have been in the single digits. This oversupplied market was the result of a MWNT [multi-walled nanotube] capacity arms race that started in the mid-2000s.

I recommend reading the rest of the posting where Dexter goes on to describe how pricing dropped precipitously from 2006 to 2009  and the resultant efforts to develop markets for the product.

US National Institute of Occupational Health and Safety sets recommendations for workplace exposure to carbon nanofibers/nanotubes

1 Reply

Earlier this week, the US National Institute of Occupational Health and Safety (NIOSH) set recommendations for workplace exposure to carbon nanotubes and carbon nanofibers. According to the Apr. 24, 2013 media advisory from the US Centers for Disease Control and Prevention (NIOSH’s parent agency), the recommendations have been issued in the new Current Intelligence Bulletin (CIB) no. 65. From CIB No. 65,

NIOSH is the leading federal agency conducting research and providing guidance on the occupational safety and health implications and applications of nanotechnology. As nanotechnology continues to expand into every industrial sector, workers will be at an increased risk of exposure to new nanomaterials. Today, nanomaterials are found in hundreds of products, ranging from cosmetics, to clothing, to industrial and biomedical applications. These nanoscale-based products are typically called “first generation” products of nanotechnology. Many of these nanoscale-based products are composed of engineered nanoparticles, such as metal oxides, nanotubes, nanowires, quantum dots, and carbon fullerenes (buckyballs), among others. Early scientific studies have indicated that some of these nanoscale particles may pose a greater health risk than the larger bulk form of these materials.

Results from recent animal studies indicate that carbon nanotubes (CNT) and carbon nanofibers (CNF) may pose a respiratory hazard. CNTs and CNFs are tiny, cylindrical, large aspect ratio, manufactured forms of carbon. There is no single type of carbon nanotube or nanofiber; one type can differ from another in shape, size, chemical composition (from residual metal catalysts or functionalization of the CNT and CNF) and other physical and chemical characteristics. Such variations in composition and size have added to the complexity of understanding their hazard potential. Occupational exposure to CNTs and CNFs can occur not only in the process of manufacturing them, but also at the point of incorporating these materials into other products and applications. A number of research studies with rodents have shown adverse lung effects at relatively low-mass doses of CNT and CNF, including pulmonary inflammation and rapidly developing, persistent fibrosis. Although it is not known whether similar adverse health effects occur in humans after exposure to CNT and CNF, the results from animal research studies indicate the need to minimize worker exposure.

This NIOSH CIB, (1) reviews the animal and other toxicological data relevant to assessing the potential non-malignant adverse respiratory effects of CNT and CNF, (2) provides a quantitative risk assessment based on animal dose-response data, (3) proposes a recommended exposure limit (REL) of 1 μg/m3 elemental carbon as a respirable mass 8-hour time-weighted average (TWA) concentration, [emphasis mine] and (4) describes strategies for controlling workplace exposures and implementing a medical surveillance program. The NIOSH REL is expected to reduce the risk for pulmonary inflammation and fibrosis. However, because of some residual risk at the REL and uncertainty concerning chronic health effects, including whether some types of CNTs may be carcinogenic, continued efforts should be made to reduce exposures as much as possible.

The recommended exposure, for those of us who can’t read the technical notation, translates to one microgram per cubic meter per eight-hour workday.  In other words, almost zero. Note that this is a recommendation and not a regulation. H/T Apr. 26, 2013 article by Elizabeth Wiese for USA Today

My Mar. 12, 2013 posting highlights some of the NIOSH research which preceded this recommendation.

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

1 Reply

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

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

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

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

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

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

Happy weekend to all!

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

1 Reply

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.

Carbon nanotubes safe handling guide from Australia

2 Replies

For anyone who’s been looking for a guide on handling carbon nanotubes, it seems the Australians released a relevant publication back in March 2012. There’s some really good information in it (happily, they covered a few items I have long been curious about). The Aug. 1, 2012 news item on Nanowerk provides more details about the document,

The potential risks from exposure to carbon nanotubes have been identified and examined in research studies. To help people work safely with carbon nanotubes, Safe Work Australia commissioned the Commonwealth Scientific and Industrial Research Organisation (CSIRO) to develop the guidance document Safe Handling and Use of Carbon Nanotubes (pdf).

I went to look at the 42-page PDF document and found this description of single-walled and multi-walled carbon nanotubes (CNT)  along with a description of the health concerns as outlined in a US NIOSH (National Institute of Occupational Safety and Health) document on p. 4 print version, p. 6 PDF,

SINGLE-WALLED AND MULTI-WALLED CARBON NANOTUBES

In general, there are two groups of CNTs:

  • Single walled carbon nanotubes (SWCNTs) are a single cylinder of carbon atoms forming a tube. They are normally around 1nm in diameter, but may be up to 5nm.
  • Multi walled carbon nanotubes (MWCNTs) consist of two or more concentric layers of carbon nanotubes with a hollow core typically 2-30nm in diameter. For example, double-walled carbon nanotubes have two concentric layers. MWCNTs may be stiffer than SWCNTs and may potentially be of greater health and safety risk due to the possibility of piercing the body’s pleural tissue.

Potential health concerns

The toxicity of CNTs is the subject of much discussion and experimentation. This document does not aim to consider or analyse this literature in detail. However, CNTs can be bio-persistent and have the potential to exist as fibre-like structures.

NIOSH (2010) reports that currently there are no studies reported in the literature of adverse health effects in workers producing or using CNTs. However use is not yet widespread, and there can be a long latency before the development of disease. The concern about worker exposure to CNTs arises from results of animal studies, showing adverse lung effects including pulmonary inflammation and fibrosis.

NIOSH (2010) also reports that animal studies have also shown asbestos-type pathology associated with exposure to longer, straighter CNT structures. Mesothelial tumors have been reported in a susceptible strain of mice after intraperitoneal injection of longer MWCNTs (10-20 μm in length) but not by short MWCNTs (<1 μm in length).

In a recent review, Toxikos (2009) reports: “Evidence leads to a conclusion that as a precautionary default: all biopersistent CNTs, or aggregates of CNTs, of pathogenic fibre dimensions could be considered as presenting a potential fibrogenic and mesothelioma hazard unless demonstrated otherwise by appropriate tests…” (Toxikos 2009).

There is also evidence that CNTs and structures of CNTs that are not of fibre-like shape may also be hazardous.

They give guidance on on two methods for risk management (pp. 5 – 7 print version, pp. 7-9 PDF),

Risk management methods — Overview

Risk management, including work with CNTs, is focused on preventing incidents, injury, illness, property damage, and environmental harm.

The general risk management process, which is applicable to working safely with CNTs, is illustrated in Figure 1. It shows that risks may be controlled with or without conducting a detailed risk assessment. If, after identifying a hazard, you already know the risk and how to control it effectively, you may implement the controls without further assessment.

Guidance on the general risk management process is available in the Code of Practice: How to Manage Work Health and Safety Risks.

This document provides guidance on two options to manage the risks.

Method 1 — Carbon nanotubes risk management with detailed hazard analysis and exposure assessment 1

This approach should be used when it is necessary to gather and evaluate information on characteristics of the carbon nanotubes or structures of carbon nanotubes and/or on potential levels of exposure throughout the process and associated work, to assess risk. The approach involves:

collecting relevant information to identify the hazards

assessing the risks

implementing appropriate control measures, and

monitoring and reviewing the effectiveness of control measures.

Information can be collected from external sources, including the manufacturer and supplier. This will include information on:

physical and chemical characteristics of carbon nanotubes

potential health effects

control options.

Specialised knowledge of the production processes, analysis methods and controls will be required to undertake a full risk management process.

Method 2 — Carbon nanotubes risk management by Control Banding

Control banding for CNTs involves a simplified form of the risk management approach, where specific controls are recommended based on process risk. The CNTs are considered to be hazardous, therefore the controls are based on the potential level of exposure. Control banding can be used when production and manufacturing processes are well understood, potential exposure routes are known and safe work procedures are developed.

As with Method 1 above, this approach involves implementing appropriate controls for specific processes and monitoring and reviewing control effectiveness.

After my encounter with Canadian firefight Peter McBride (he disagreed vociferously with some of my comments in an April 25, 2012 posting), I’ve been interested in any fire safety issues posed by nanomaterials. There’s not much in this report but here it is (p. 10 of the print version, p. 12 PDF),

Safety hazards are considered in the CSIRO’s safety data sheet for MWCNTs (CSIRO 2009). CNTs are not considered to be dangerous goods. In relation to fire and explosion hazards the following points are noted:

  • CNTs are difficult to combust and ignite.
  • However in general, accumulations of fine dust (420 microns or less) may burn rapidly and fiercely if ignited; once initiated larger particles up to 1400 microns diameter will contribute to the propagation of an explosion.

This is the last bit I’m excerpting from the report and it’s an example of how ventilation practices were changed to bring exposure rates to airborne CNTs below recommended levels,

REDUCING EXPOSURE TO AIRBORNE CNTS — EXAMPLE

An assessment of airborne exposure to MWCNTs in a research laboratory manufacturing and handling MWCNTs found a total particulate concentration of 430 μg/m3 for a blending process in the absence of exposure controls (Han 2008). The implementation of ventilated enclosure of the blending process reduced airborne concentrations of MWCNTs from 172.9-193.6 tubes/cm3 to 0.018-0.05 tubes/cm3. At airborne levels of 0.018-0.05 tubes/cm3, the airborne MWCNTs concentration is significantly below the NIOSH REL of 7 μg/m3.

I included that last bit as it demonstrates the possibilities for minimizing risk. Unfortunately, there’s no way yet of ascertaining whether the minimum levels for exposure have been set correctly.

So, here’s my final word on this guide, it provides some good introductory material, guidelines for analyzing  the best safety practices, a helpful bibliography, and a reminder that we still don’t know much about the risks of handling CNTs. For those who won’t make their way through a 40-page document, there’s an information sheet.