Nanotechnology Blog

Handling of Nanomaterials

Posted on October 13, 2013 by Walt | Permalink 0

Unfortunately, there currently is not a site or an authority that you can go to and find the proper methods for handling nanomaterials. We don’t know the properties of the materials throughout the size ranges to be able to develop a specific directions for handling each different material. The Compact Fluorescent Light Bulbs (CFLs), which contain micrograms of mercury, have an Environmental Protection Agency (EPA) procedure for cleaning up the residue of a broken light (http://www2.epa.gov/cfl/cleaning-broken-cfl). The procedure starts with having people and pets leave the area. What do we do with nanomaterials?

Are nanomaterials more dangerous than CFLs? or less dangerous? In the vast majority of cases we don’t know. There has been initial efforts undertaken. OHSA awarded Rice University a contract to develop a short course on nanotechnology safety. This 8 hour course is available on the OSHA web site. In January 2013, NSF awarded Texas State University a contract to develop two courses (Introduction and Advanced) on nanotechnology safety education. The first roll out to students was started in Summer 2013. Modules from the courses are being evaluated during the Fall semester. More will be discussed on this effort in future blogs.

This takes us back to the question of “How do we handle nanomaterials?” First, let’s start with different categories of potential dangers. We will cover the handling issues in future blogs.

The first consideration is Toxicity Issues. Are there any known issues regarding the material under investigation/application? If there are, then existing procedures must be followed. One can not assume that a change in size reduces the toxicity. If Chemical Dangers are present, the established precautions must be followed. There are certain materials that have a high probability of Fire dangers. Others have concern about Explosion possibilities, which also ties into concern about Dust. Supposedly benign materials like flour can create an explosive environment if sufficient dust becomes airborne. Dust has additional hazards due to the ability to ingest the dust, which can aggregate in lungs or other parts of the body. Electrostatic issues are of a concern due to the fact that particles can cling to the researcher without his/her being aware and cause contamination outside the controlled environment.

There are other considerations that impact the approach to handling various materials. The Volume of the material is an important consideration as well as its Density. The Concentration of the material also fits into the considerations for the appropriate means of handling it. There are concerns that the Shape of the material will impact its ability to enter the human body. Straight shaped materials have the ability to more readily enter into a person’s body than Curved material. The fact that carbon nanotubes are needle-shaped, which is similar to asbestos, has raised concerns about the applications of the nanotubes. As a free floating “dust” there could be significant issues. Curved materials have a harder task in getting through some of the body’s defenses and are of somewhat less concern. The last item in today’s list is Size. There are some materials that have different shape characteristics depending on whether they are < 8nm, 8 to 20nm, or >20nm. One can not assume that the nanomaterials will keep the same structure as the size changes.

So what does one do? One method, which is reasonable safe, is to treat all materials as potentially dangerous until proven otherwise. In the evaluation of the potential dangers, one must consider all aspects of the material’s known properties and any proven properties of the nanomaterial. We will have more comments on this in the next few weeks.

Nanotechnology Risk Management, Nanotechnology Safety

Health & Environment

Posted on October 6, 2013 by Walt | Permalink 0

Building on the overview, two weeks ago, of Nano-Safety, this week’s blog will present some thoughts from the second pillar of Nano-Safety, which is the “Impact on People and the Environment.”

There are various applications on nanotechnology that make products lighter, stronger, more durable, and able to have unique properties, like stain repellant. It is possible to acknowledge the benefits of various nanomaterials and then have a long conversation on whether the benefits are worth the risk. However, the issues of applying various nanomaterial technologies to cure serious illnesses and save lives is a different story. Lives are precious and so a greater understanding of the impact of nanomaterials on the human body is important. For instance, significant advances are being made in the treatment of cancer by employing customized molecules that incorporate nanoparticles and deliver them to cancerous sites. These specialized molecules either deliver specific chemicals or other material like gold or carbon nanotubes to the site requiring treatment. The chemicals will react with the cancer and begin destroying it. The other materials can be heated by many different methods and destroy the cancerous cells through the elevated temperatures. These approaches promise significant advances in treatment of diseases; however, the long-term impact on the body is under investigation and no definitive answers exist.

The first issue is, of course, what will be the impact on the person undergoing treatment. Will they be cured or at least put into remission? If we consider that the outcome will not be certain for 5 years, 10 years, or longer, how do we make a short term decision? In addition, since the effort is being conducted on people, the approval process for the U.S. Federal Drug Administration can take 7 or more years to obtain all approvals for a wide distribution of the process/product. Consequently, the situation exists that any development efforts can take a very long time to determine the effectiveness. So, controls are needed for the handling of these materials. The next issue that arises is what happens to the nanomaterials after they have performed their function. Fundamentally, either these particles are retained in the body or they are eliminated from the body.

If the nanomaterials are retained, the question that must be answered is the accumulation of these elements beyond a point where they themselves become toxic. There have been studies on toxicity levels and regulations by Government agencies on the maximum exposure permissible, which is significantly below the point of toxicity. As new compounds are developed, constant evaluation provides for adding information for guidance.

What about the situation where the particles are eliminated from the body? If there are environmental dangers, hopefully, the process is well contained and proper disposal is performed. Some people are alarmed that controls will not be followed and it will cause environmental damage. Yes, there needs to be an understanding of the potential environmental damage. In of itself, that is a good goal, but it is not sufficient. We, human beings, do not fully understand the working of the ecological system that is the Earth. One example of this is that the oceans naturally leak various types of petroleum. It has been found that there are microbes that live on reducing the leakage residue to a benign state. Certain type of pine trees (Bishop Pine among others) require a fire to destroy the mature trees for them to regenerate.

We need to understand the properties of nanomaterials and their effect on people and the environment. Then we can make sound judgments on the handling of the materials. But, this brings up the question, what are the nanomaterial properties? Nanosilver is known to prevent bacteria from causing infection. Bacteria appears not to be able to develop a resistance to the nanosilver as the bacteria has been able to do against modern medicines. The other side of the issue is that minute concentrations of nanosilver can be toxic to small life forms, which can be harmful to the environment. How do we determine the potential danger of materials with unknown properties?

What should be done? One answer that you will hear is any usage of the questionable material should be banned. Governments have tried that in many different ways. It drives the application and experimentation underground or to other places that do not have the ban. So that is not a good answer.

Currently, there are many industries that use materials that are considered toxic. The key to the successful application of these materials is that the workers are trained and procedures in place to reduce the potential for any accidental exposure or release of the material. But, we don’t know the potential dangers of most nanomaterials. What do we do? Next week I will discuss how to approach the process for training people to handle the unknowns of nanomaterials.

Nanotechnology Health

Regulations of nanomaterials

Posted on September 29, 2013 by Walt | Permalink 0

Regulations and MSDS

Entering into the world of nanotechnology provides numerous surprises. In our last blog, we provided an overview of the four pillars of Nano-Safety. This week will be about material properties, but from a regulatory perspective. There are many concerns by regulatory agencies regarding the effect of nanomaterials on both people and the environment. Rules are passed and orders issued that researchers and companies need to follow. While the details below are from a few years back, they indicate the potential impact of regulations. The first case demonstrates how different organizations within a Government Agency can issue conflicting directions.

Manufacturers of nanoengineered products are getting frustrated by the uncertainties about the regulatory definitions of chemicals, materials, and products made with nanotechnologies. In 2010, the U.S. Environmental Protection Agency’s Office of Pesticide Programs (OPP) came out with its definition of a “nanoscale material”: “an ingredient that contains particles that have been intentionally produced to have at least one dimension that measures between approximately 1 and 100 nanometers,” along with a new policy stating that an active or inert ingredient will be considered new if it is nanoscale. But the size-based focus of that definition is different from the 2010 one used by the EPA’s Office of Pollution Prevention and Toxics (OPPT), which says size alone does not determine whether or not a chemical is new, and therefore subject to review under the Toxic Substances Control Act (TSCA). [1]

Unfortunately, one is not given the ability to choose which rules to follow. Typically, one can be cited for non-compliance for not following either of them, even though there are in conflict with each other. And, it is not possible to follow both of them.

Consider the next case where a city government issues an ordinance that researchers are required to observe.

The City of Berkeley, California passed an ordinance in December 2006 requiring information be provided on all nanomaterial that will be brought into the city. [2] However, Material Safety Data Sheets (MSDS) do not exist for the majority of nanomaterials. So what to people do? They must comply with the regulations. So what are the options? CNTs have been classified as graphite (a form of carbon). Diamonds and coal dust are also forms of carbon. So does that mean that the MSDS for graphite can be employed for other forms of carbon? Of course not. But, what does a researcher do? There is no simple answer.

If laws are passed requiring information that is not known, people will provide the best information available, which may not be accurate. We need to be able to address these issues, but there is not a systematic approach in place. This is the real problem. We do not have accurate information that can provide guidance in developing regulations and standards. This blog is more of raising awareness. Quick solutions are not available.

On a different note, there have been some very interesting research papers that have come to my attention in the last few days. “MIT and Harvard create new, lightsabber-like state of matter: Photonic Molecules.” [3] Research done in vacuum and at very low temperatures has created “two-photon” molecules. These photons behave like a molecule. The reference link provides for some interesting reading. Another MIT paper [4] indicates researchers have found a new type of magnetism. The projection is that the “quantum spin liquid” could lead to new type so memory devices. As with any experimental results, these need to be verified by independent researchers. However, the concepts themselves are interesting. If the work can develop further, there could be some significant advances in devices. One thing that underlies these findings are the tools that permit the measurement of interactions in the nano realm. As the tools improve, more and more “interesting” properties will be found. Which fact brings us back to the question, how can we appropriately regulate materials that we have no idea of their true nature?

From Meridian Institute Nanotechnology Portal on Tuesday, May 18, 2010 http://www.merid.org/NDN/
http://www.seektress.com/berkeley.htm
http://www.extremetech.com/extreme/167439-mit-and-harvard-create-new-lightsaber-like-state-of-matter-photonic-molecules
http://www.extremetech.com/extreme/143782-mit-discovers-a-new-state-of-matter-a-new-kind-of-magnetism

Nanotechnology Risk Management

Nanotube Computer

Posted on September 26, 2013 by Walt | Permalink 0

There has been an interesting report from Stanford University. The researchers have developed a working computer that is based on carbon nanotube electronics. This is the first time that a working computer, albeit primitive by today’s standards, has been demonstrated using wafer-type manufacturing. The article in the Wall Street Journal is available at http://online.wsj.com/article/SB10001424052702304795804579097201829598522.html.

As significant developments occur in nanotechnology, we post links for further exploration of the information.

Nanotechnology, Technology

Nano-Safety

Posted on September 21, 2013 by Walt | Permalink 3

Nano-Safety

What is safety with respect to nanotechnology? In the simplest terms, it is the development, manufacture, application, and control of nanomaterials in a manner that minimizes potential issues, both known and unknown that may impact both people and the environment. All chemicals can kill one, it is just a matter of quantity. Dangerous materials, even poisons, can be beneficial if applied in the proper dosage. Just because something is dangerous does not mean it should not be used. Fire is dangerous if mishandled, but does that mean we should not use it?

One concern about safety in handling nanomaterials is based on the unknown issues. Not knowing the impact on people or the environment can lead to unfounded concerns and a reluctance to accept developments. This is not only true for nanomaterials but many commonly employed materials/processes when they were first introduced. If you want to examine issues that have long had proponents and opponents, examine the application of milk pasteurization or the case of adding fluoride to drinking water.

In approaching this problem, I have proposed that the issue of Nano-Safety can be addressed a systematic manner that involves 4 key concepts or pillars, which are: 1) Nanomaterial properties; 2) Impact on people and the environment; 3) Handling of nanomaterials; and, 4) Business focus. Last week’s blog covered some of the different material properties that have been found. I will cover each of the remaining ones in future blogs. This concept was developed in a white paper on Nano-Safety in 2007.[1] The 4 concepts below are from the white paper and used with permission.

”1) Material Properties: Obviously, one aspect is the development of an understanding of the properties of all the materials, a situation complicated by the lack of availability of metrology tools. A more fundamental question is what properties should be investigated. If the starting point is to ensure an understanding of the impact of the nanomaterials on people and the environment, then investigations can be focused on material properties within the expected operational parameters, like room temperature, atmospheric pressures, etc. Understanding the properties is necessary before it is possible to understand their impact.

“2) Impact on People and the Environment: Another aspect is a greater understanding of the impact of nanomaterials on the human body. For instance, significant advances are being made in the treatment of cancer by employing customized molecules that incorporate nanoparticles and deliver them to cancerous sites. These specialized molecules either deliver specific chemicals or other material like gold or carbon nanotubes to the site requiring treatment. The chemicals will react with the cancer and begin destroying it. The other materials can be heated by many different methods and destroy the cancerous cells through the elevated temperatures. These approaches promise significant advances in treatment of diseases; however, the long-term impact on the body is under investigation and no definitive answers exist.

“3) Handling of Nanomaterials: The question of handling and storing Nanomaterials is important from both the implications for the people involved and the impact on the environment. Yet, without any knowledge of the basic properties, the extent of the precautions required is unknown. One always wants to err on the side of safety, but potentially onerous procedures, based on worst-case scenarios, will diminish the progress being made in applying nanotechnology to everyday problems. Procedures are required based on fundamental evaluations and historical efforts.

“4) Business Focus: The business aspect is important. Given the fact that businesses need to protect their workers as well as their corporate liability, they need to operate according to established guidelines. These guidelines do not exist! Consequently, there is the potential for significant corporate liability.

“NANO-SAFETY is not something that will come into place before there is a need, and the need is today. The application of nanomaterials has been happening for some time. Unlike earlier times in history when people simply proceeded and ignored the consequences, today’s environment requires that people and organizations be responsible for their actions. Action is required.”

Closing thoughts

The intent of including references is to provide a starting point for anyone who wants to learn more. I received one post that indicated the writer was going to do some checking of both the included references and others to check the assumptions presented. That is great. Investigate, Learn, Decide.

References:

Available at http://www.tryb.org/a_white_paper_on_nano-safety.pdf

Nanotechnology Safety

When is “nano” really nano

Posted on September 14, 2013 by Walt | Permalink 5

The common definition of “nano” is when one dimension of a material is less than 100 nm. The definition from a Google search [1] on “What is nanotechnology?” yields the following: “the branch of technology that deals with dimensions and tolerances of less than 100 nanometers, esp. the manipulation of individual atoms and molecules”. Wikipedia references [2] the National Nanotechnology Initiative’s definition, which includes: “…which defines nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers.“ Since governmental regulations are based on this definition, let’s consider if this is a realistic method of defining nanomaterials. There is a wealth of material to consider, but only the following properties will be considered in this blog: surface adhesion, color, melting point, conductivity, reactivity, and magnetic moments.

SURFACE ADHESION: There are a number of different ways to consider surface adhesion. The nano realm does not behave in ways we normally experience. The semiconductor industry requires extreme cleanliness. The issue of adhesion came to the forefront when the removal of 50 nm particles from imaging masks was an absolute necessity. The evaluation of the particle removal indicated that particles below 70 nm or 80 nm would adhere more strongly to surfaces. When the size of the material drops below 80 nm, van der Waals forces become the dominant mechanism for particle adhesion. Work in other areas have provided the ability to make glass that is self-cleaning by minimizing the ability of particles to the surface. Contrary to the perception that the flatter the surface, the harder it will be for particles to adhere is not a truism. The picture below shows a lotus leaf structure [3] which is the basis of the design of self-cleaning surfaces. By creating a surface that does not present a flat surface for materials to adhere to, the contaminate is naturally rejected.

COLOR: As mentioned in a previous blog (August 30^th, 2013), the application of nanomaterials has been employed for millennia. Nanoparticles of gold have been used to give glass a red color. The picture below is from a Smithsonian article [4] and references the pictures as being supplied by the British museum. The goblet appears to be green colored until light illuminates it from the rear. It then shows its reddish color. The effect is caused by particles about 50 nm imbedded in the glass.

MELTING POINT: Over the centuries, one constant that people learned is that materials have a constant melting point. Gold melts at 1064.18^oC, which has been determined experimentally. In fact, the various melting points for different materials can be employed to remove impurities and obtain more pure amounts of the specific material desired. Recently, the ability exists to examine the behavior of smaller sized particles. What has been found is that below 50 nm the melting point of materials begins to diminish. The curve below [5] shows the decrease of the melting point of gold as the size is diminished. [A starting point for additional information on this effect is available in reference 6.]

CONDUCTIVITY: In many respects, the conductivity issues is similar to the melting point issue. Conductivity is a bulk material property that is perceived as being a constant. Except that we are now able to work with very small material. Copper, a material valued for is conductivity, starts to have potential issues as the width of the conductors shrink below 50 nm. Effects of grain boundaries and crystal orientation can cause two similar sized conductors to have different conductivity. Consequently, precautions are required in semiconductor manufacturing processes to minimize the potential variance among conductors.

REACTIVTY: The increase of surface area provides for an increase in reactivity. This is one of my favorite points when someone wants to include all material under 100 nm as being nano and should be considered the same regardless of the size. Consider a jar of 80 nm aluminum particles. How carefully should it be handled? There is the obvious concern about opening it and having some of the dust inhaled or possible attached to one clothing. It is advisable to be cautious, but there is nothing obviously dangerous about the container and its contents as long s proper handling is observed.

According to the desire to create one classification of all 100 nm or smaller similar material, in this case aluminum, it makes no difference as regard to the size of the material. Consider a jar of 30 nm aluminum. Obviously, the same precautions need to be taken as the 80 nm material. BUT, and this is a key difference, 30 nm aluminum particles react when exposed to air (oxygen). Chemists classify the reaction as being very energetic. To the lay person, it is an explosion! Yet some regulation agencies want to classify both sizes as being identical. Really? There is some effort in France to include exposed surface area in the classification of nanomaterial.

MAGNETIC MOMENTS: There are a limited number of materials that are considered to have magnetic properties. The nano realm always provides surprises. “There are a number of materials that are known to have magnetic properties, and they do not include either silver or platinum. However, 13 atoms of silver have been shown theoretically to have a magnetic moment, and 13 atoms of platinum has been shown experimentally to have a magnetic moment. [8 & 9] This is a new property for these metals.”[7]

THOUGHTS: Establishing a standard or regulation based on a simple property as 100 nm or less does not guarantee that the issued document appropriately addresses the concerns. Material Safety Data Sheets (MSDS) become questionable at best. A nano-MSDS that is 17 pages long will not be effective, nor are there enough resources to produce an MSDS for each 1 nm variation of particle size.. The effort of DuPont and the Environmental Defense Fund to develop the Risk Framework is an excellent starting point. But, how does one really know what the material properties are. If there are a distribution of particles, and there are always some size differences, how does one quantify the material properties? Our experience is that we can go to a table and find a property, but at the nano scale the properties are changing with size. Does a distribution of 10 nm gold particles (0.5 nm half-width) have the same properties as a similarly sized distribution with a half-width of 3 nm? Will they melt the same way? What happens when one looks at the impact of multiple effects on the nanoparticles? Currently, bulk material properties have two-dimensional curves for the properties, e.g., the boiling point of water is a function of temperature and pressure. Does this imply that the proper description of nanoparticles will need to be three-dimensional? Or multi-dimensional? More on this topic in a later blog. Please feel free to submit comments and/or questions.

References:

https://www.google.com/#q=what+is+nanotechnology Google
http://en.wikipedia.org/wiki/Nanotechnology Wikipedia
http://phys.org/news2730.html
http://www.smithsonianmag.com/history-archaeology/This-1600-Year-Old-Goblet- Shows-that-the-Romans-Were-Nanotechnology-Pioneers-220563661.html
http://www.carolina.com/teacher-resources/Interactive/what’s-so-unusual-about-nanomaterial-melting-points%3F/tr23010.tr Carolina site
http://en.wikipedia.org/wiki/Melting-point_depression
Chapter 14 Nano Risk Assessment, W. Trybula and D. Newberry, Nanotechnology Safety, Ramazan Asmatulu editor, Elsevier Publisher 2013/4
NanoTechWeb.org, May 30, 2006 posting http://nanotechweb.org/cws/article/tech/24983
NanoTechWeb.org, January 10, 2007 posting on University of Stuttgart report

Misc Ramblings, Nanotechnology

Two-dimensional Materials?

Posted on September 8, 2013 by Walt | Permalink 2

Graphene is one form of carbon atoms arranged in a densely packed hexagonal lattice. It has been called a two-dimensional material due to the fact that most references are to the form of the material that is only one atom thick. The properties of the material are, of course, significantly different from bulk graphite. Not surprisingly, two atom thick material has different properties from one atom or three atom thick material. As the number of atomic layers increases, the material properties become the bulk properties. There is large amount of research that needs to be completed before we can truly understand the benefits and challenges of the material.

As with almost all novel materials, there are reports of possible dangers. The three references at the end of this blog link to comments about work originally published from the Brown University [1] and the University of Edinburgh, UK [2, 3]. If one reads the reports, they present a scenario where it might be possible to have an adverse effect on people. But, knowing the potential and ensuring the necessary precautions are taken should mitigate the possibility of harm. A very sharp knife is dangerous if mishandled. Hopefully, all of us handle them with adequate caution.

Graphene is a pure form of carbon. There are other possibilities where other atoms are introduced into the carbon matrix and result in totally different properties. However, having the same dimensional thickness, the concerns raised above will still apply.

Graphane has the same honeycomb structure as graphene, except hydrogen atoms are introduced into the lattice and attach themselves to the carbon. The resulting bonds between the hydrogen and carbon atoms effectively change the conducting structure of graphene to the insulating properties of graphene. Even with this addition, graphane retains the thinness, super-strength, flexibility and density of graphene.

There are other two-dimensional materials that also have interesting properties. Boron Nitride has seen significant research. There is a 2012 article in IEEE Spectrum [4] that indicates Molybdenum Disulfide cold be a choice for future electronics.

Carbon Nano Tubes (CNT) are the same basic structure as graphene, but exist in a tubalar form. Depending on the chirality (direction of roll of the carbon matrix), the material exhibits conductive or semiconducting properties. With conductive, insolating, and semiconducting properties, the question is how soon will there be electronic applications of these materials.

The answer requires that there be a manufacturing process developed. Current semiconductor manufacturing produces billions of transistors for single devices through a process that creates the transistors via an additive process. Considering that millions of devices are produced each week, the number of individual transistors produced per second is very large. Current development efforts of nanoelectronics are still very slow compared to semiconductors. Developments in the manufacturing process are required before nanomaterial based electronics become affordable.

One parting thought for this week’s blog. If we can change graphene (conductive) to graphene (insulating) by adding hydrogen, will this or other changes occur naturally when the device is exposed to an operating environment? If it happens, then the properties of the device will change in a way that will not be beneficial.

Next week’s blog will consider the classification of nanomaterials based on size alone.

Nanotechnology, Technology

nanotechnology research

Posted on September 2, 2013 by Walt | Permalink 0

Nanotechnology can be a controversial topic. There are numerous reports that are published showing that a specific nanomaterial (pick your favorite one) is beneficial or is harmful and dangerous. The editorial cartoon by Gary Markstein on coffee readily applies to the current state of nanotechnology. Just substitute your favorite material in the place of the word coffee.

So what is the truth? One must realize that there are many ways to approach an evaluation of the results of scientific study. Without scientific results, one only has speculation and projections by interested parties. Reported “scientific” findings that do not contain data are suspect. (In a future blog, we will consider the corruption of scientific research.) The purpose of publishing scientific experiments and results is so that others can replicate the experiment and validate the results. The purpose of including data is so that people can understand the significance of the results. A statement that carbon nanotubes have shown effects similar to asbestos in reacting with lung tissue without providing data will cause a reaction to “do something” immediately. Adding the fact that the carbon nanotubes were made to be extra-long and applied in a very great concentration that would not normally be encountered does not create the same urgency.

The British Royal Society of Chemistry states: “While there is no such thing as a safe chemical, it must be realized there is no chemical that cannot be used safely by limiting the dose or exposure. Poisons can be safely used and be of benefit to society when used appropriately.“ So our approach to development and applications of nanomaterials should also be one of caution, but the results need to be truthful.

Nanotechnology, Science

nanotechnology

Posted on August 30, 2013 by Walt | Permalink 0

Nanotechnology has been applied since the time of ancient Greece. Our ability to observe, measure, control, and modify in this size realm is of recent development. The ability to work with nanomaterials has opened up numerous possibilities with both proponents and opponents of various developments. This blog is directed at providing information and not judgments on nanotechnology.

Nanotechnology normally refers to the size of the material being considered. Nano is a modifier that is employed to indicate 10^-9, or one billionth of the object in question. A nanometer (nm) is one billionth of a meter. A 1/2 in marble is approximately one billionth of the size of our world. How the modifier is employed makes a difference. Actually, the term “nanosafety” means one billionth safety, which is not very safe. The appropriate use in talking about safety with nano is either “nanotechnology safety” or a shorter “nano-safety”.

Nanotechnology