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THE ISSUE WITH CARBON NANOTUBES: TOXICITY AND NANOETHICS
Angela Chang (anc156@pitt.edu)
BACKGROUND
The interest in the field of nanotechnology has
burgeoned to great heights in recent years and as a result
carbon nanotubes have been popularized and become
prevalent uses in many products. Carbon nanotubes can be
used to create photovoltaic cells for solar energy, which has
been very promising in replacing oil from the latest research.
Developers in carbon nanotubes have found methods of
making the energy efficiency improve so much that it is now
a viable option and competitor with other forms of alternate
energies in the energy industry. However, the use of carbon
nanotubes, in some cases, has become extremely
controversial. There is evidence that may suggest that there
are harmful effects of exposure to carbon nanotubes; but not
all types of carbon nanotubes are detrimental to the
environment and people’s health. There are so many
different attributes and processes to the creation of a carbon
nanotube, that some combinations and additives may make
them dangerous, while others are fit to be part of the human
body. In the following sections, I will discuss the overall
situation of my team’s current project, controversies of
carbon nanotube radiation, the different violations of code of
ethics and how some of the canons in engineering codes of
ethics conflict with one another.
BASICS OF NANOTUBES
Carbon nanotubes are essentially thin sheets of
carbon rolled into a tube the size of a nanometer (onebillionth of a meter.) Because of the size of carbon
nanotubes, basic laws of physics do not apply. Rather,
carbon nanotubes follow rules on a quantum level [12].
CREATING CARBON NANOTUBES
Carbon nanotubes can be created through a process
called laser ablation. This is when a laser causes graphite(an
allotrope of carbon) particles to undergo vaporization and
are baked in an oven-like mechanism. When the carbon
atoms begin to cool off, they recombine and form tube-like
structures and eventually become solidified [13].
ELECTRICAL CURRENT
In a photovoltaic cell composed of nanotubes, the
photons from the sun are absorbed and converted into
electron hole pairs called excitons [14]. The exitons quickly
travel to another layer of the device so it will not get
absorbed by the material and is able to generate an electrical
current due to the charge separation [14].
University of Pittsburgh, Swanson School of Engineering 1
Submission Date 2014-10-28
FIGURE 1 [12]
Electric current produced by carbon nanotubes.
Nanotubes can have different diameters and twist
on the tube. This is known as chirality. Different chiralities
can affect the way light is absorbed and the type of light that
gets absorbed based upon the light’s wavelength and
frequency [15]. A single-chirality nanotube can only take in
approximately one percent of the sunlight’s energy, making
them have little efficiency. Researchers at Northwestern
University have recently discovered a new method of
making nanotubes to have multi-chirality. This new method
has allowed for scientists to see up to three percent
efficiency of absorbing the sun’s electromagnetic
radiation(light)[15]. Though this is not a dramatic increase,
the efficiency still rose to three times its original amount by
making a few small altercations. The increase in power
conversion efficiency (PCE) in a certain type of organic
carbon nanotubes started from “less than 1% in 2005 to 45% in 2005, 6% in 2009, 7.4% in 2009, and 8.3% in
2011”[4]. From this data, we can see that there has been a
steady increase ever since the popularity of carbon
nanotubes began and is projected to continue to rise. More
methods were later found by making further changes to the
efficient model of the carbon nanotube. This would allow
the carbon nanotube to have energy conversion efficiencies
that could compete with other major renewable energy
methods in the solar industry.
INCREASING ENERGY EFFICIENCY
Single-walled nanotubes absorb a wide range of
wavelengths. Researchers at MIT have combined the effects
of both the multi-chirality and single walled trait in carbon
nanotubes to create single-walled poly-chiral nanotubes that
Angela Chang
absorbs more of the infrared spectrum as well as the visible
light spectrum and generates a quicker current, which
increases the efficiency of the photovoltaic cells. These
researchers also maximized the voltage from the solar
energy cells by creating an interface between the
photovoltaic layer and the transport hole layer, allowing
electrons to better recombine, and making an efficiency of
forty-two percent [3]. This matches up to some of the more
widely used metal solar panels. However, carbon nanotube
photovoltaics have other competing qualities that overpower
those of metal solar panels.
being much lighter than steel by a factor of six. The reason
for this strength is because carbon-carbon bonds have a very
stable electron configuration. Another reason for its strength
and durability is because carbon nanotubes are made only
out of sp2 bonds which are more durable than the sp3 bonds
in the structure of a diamond [5].” Sp2 hybrid orbitals have
shorter bonds that sp3 which means that the effect of the
strong nuclear force is greater on sp2 orbitals in the carbon
nanotube, which is why they are stronger than diamond, and
therefore the strongest material on earth. The hollow inside
of the tube structure makes the carbon nanotube easy
flexible and easy to manipulate. This is probably why
“CNT’s are the second most used nano-product today
[5].”The average atomic mass of carbon is less than that of
steel, meaning that carbon bonds would be lighter. If carbon
nanotubes became even more prevalent than they already
are, the costs of shipping materials and final products such
as solar cells would be dramatically reduced, and materials
would not suffer from heat damage or breakage during the
transport. This would reduce the amount of defective
products that go into trash bins every year.
NANOTUBES VS SOLAR PANELS
EFFECTS OF HEAT
In recent years after the introduction of metal solar
panels, there have been incidents of fires due to the
excessive heat caused from energy absorption of the solar
cells[3]. This issue has harmed and even killed a multitude
of individuals, along with damaging the reputation of solar
energy as a viable option for the future of the world’s power.
But since carbon nanotubes are nonmetal semiconductors,
they are poorer conductors of heat. Thus, using carbon
nanotubes for conducting electricity will be economically
efficient because the nanotube device will not get damaged
and wasted before their time. Metal solar cells that may have
same degree of energy efficiency but suffer heat damage and
have to be disposed [5] The reason why carbon nanotubes
are more resistant to heat yet still good conductors of
electrical current is due to the fact that carbon nanotubes are
spherical, whereas metals are ions that form in the shape of a
lattice(three dimensional array) and during electricity
conduction, the electrons create heat by friction between one
another. Carbon nanotubes are composed of “spheres” called
fullerenes that have an empty center. These sphere-like
molecules have little contact between its electrons. This also
means that with less electron-electron interference, carbon
nanotubes are much quicker at moving through an electrical
current [5].
POSSIBLE IMPLICATIONS OF CARBON
NANOTUBES
If carbon nanotube photovoltaics truly become safe
and successful, the biggest impact of their low cost energy
efficiency and clean sustainability will be on third world
countries. Particularly the rural areas many people do not
have access to electricity. With carbon nanotube
photovoltaics, we can supply solar energy to the millions
living below the poverty line at a very low cost [17]. Once
supplied, because the strength and durability of carbon
nanotubes, maintenance costs will be minimized compared
to other forms of energy.
TOXICITY
Initially some people were not sure if these
nanotubes were toxic to the human body, but it is now
confirmed that certain types of do have toxicity. Structurally,
carbon nanotubes are asbestos like in their fibers: long, fine
and needle-like structures that are inhaled without
recognition until it is too late [16]. For normal particles, our
macrophages will engulf and clear particles that are inhaled
from the lungs, however, for longer and thinner structures
such as asbestos and carbon nanotubes, macrophages will
have a harder time dealing with the recalcitrant and
hazardous fibers. In order to minimize reactivity and
toxicity, it is best to keep the raw form of CNT without any
additives, which can sometimes produce a metallic character
in the carbon nanotubes. Heating the carbon nanotube can
also reduce overall toxicity [3].
AN OPTIMISTIC PRODUCT
PRACTICALITY AND STRENGTH
Since carbon nanotubes can only display the
properties of a nonmetal, this must also mean that unlike
metals, carbon cannot oxidize and would therefore last a
much longer time before the carbon nanotube photovoltaic
cells begin to rust from weather. In addition, since carbon
nanotubes are millions of times smaller than the metal solar
panel analogs, they can also fulfill a society’s aesthetic
purposes by having less clutter in suburban and urban areas.
Carbon nanotubes are hard to break and have properties
stronger than that of steel by a factor of 100, while also
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Angela Chang
We developed a unique form of carbon nanotube
that has a sixty-seven percent rate of energy efficiency after
several trials and structural adjustments by the first two
weeks. We sent the finished product to the lab for regulation
testing. A few days ago, we received the report of the effects
of our developed carbon nanotube on mice. However, we
decided that in order to save money, we only asked for them
to find and give us the raw data and we would hire a
statistician to interpret it after it was received. When we
received the data, I and two other workers decided to
interpret the data ourselves to get a good sense on the carbon
nanotube safety. Unfortunately, we have found that the
specific type of carbon nanotube we have created have a
significantly high risk of cell death. We kept a copy of the
raw data and our statistical analysis on a flash drive.
Two days later, the statistician supplied us with his
results and interpretations of the raw data on the effects of
our carbon nanotube on mice. Shockingly, he said that there
was no statistical significance that the nanotubes were toxic
at all, and were actually relatively safe for humans to be
exposed to it and use. A colleague and I look at the
“original” raw data and compare it to the raw data from two
days ago. We discover that the original results have been
adulterated. I later come into the office to see colleague Z
who sent in the data to the statistician. As I was about to talk
about my findings, I notice that in his trash bin are the old
results of his original interpretation for the data that
indicated the nanotubes were hazardous. On his desk were
the incongruous results that were obviously changed. I
pretend that I don’t notice.
I confront the boss who he says that he approved of
the colleague Z to alter the data because he’s good at
statistics. He said that, although the data was not undisputed,
the toxicity of the carbon nanotubes was only statistically
significant to a small degree and that they were virtually
harmless. The company was doing well, and he did not want
to risk losing the support from the organization. He said that
if I kept quiet about the situation, I would get a higher
commission for the project than the other members.
FIGURE 2 [11]
Researchers tested carbon nanotubes on the lungs of mice.
They discovered that not only have the lungs become
inflamed from the carbon nanotubes, the conspicuous black
carbon nanotubes have built up inside the lungs as well
[11]. Although humans will not be exposed as directly as
shown through this experiment at such large
concentrations[17], the human lungs and filtration process
are so homologous to mice that the above display could be
the build up in a span of a few decades from toxicity.
TOXIC VS NON-TOXIC NANOTUBES
The risks of the carbon nanotubes depend on type,
shape, arrangement of the nanotube and whether it is single
or multi-walled. These different combinations can produce
anywhere from benign to adverse affects on the human body
and the environment [3]. Carbon nanotubes also have
additives to them that are more difficult to remove once put
in. Some of these chemicals may have serious chemical
reactions depending on what it is exposed to in the air [3].
Therefore, the safer type of carbon nanotube is the pure kind
where no additives are present. It is also uncertain whether
the additive will have a different reaction when it is inside
the carbon nanotube versus when it is taken out of the
carbon nanotube. This type of analysis requires several trials
and more research, something that may be hard to do
because of the demand of nanoproducts. It will be very hard
to see the long-term effects of the many different carbon
nanotubes.
POSSIBLE PROCEDURES TO TAKE
A deontological decision would be to keep my
loyalty to the company and do nothing. On one hand, it is
necessary to “Act for each employer or client as faithful
agents or trustees [1]”, meaning that I should be a loyal team
member to my co-workers and build trust without deception.
Canon five states that I should also “avoid deceptive acts
[1].” This means that I should not go behind my fellow
teammate and boss’ back to alert the authorities about their
behavior. On the other hand, if I kept my loyalty to the
company, I would also be in part of deceiving everyone else
who would later suffer the consequences. The boss has also
committed bribery, a violation of canon five that prohibits
the giving of a reward in order to “secure work [1].” If I
accepted this bribe, I would be in the part of encouraging
THE DILEMMA
I am on a team of fourteen engineers at EmiSol Inc,
a nanotechnology company based in Switzerland that is
working on improving the use of carbon nanotubes for solar
power. Because of the progress we have made in the recent
months and the increasing demand of solar energy, the
Global Solar Energy Society, has decided to increase its
funding for this project, and set the quota to have the project
finished by the end of this month. If we do not finish the
project, we might risk losing the funding from energy
society because of a similar but original project being done
by a competitor.
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Angela Chang
unlawful practice [1], violating the fifth rule of practice in
the engineering code. I would also be hugely disrespectful to
the other team members, who have done equal amounts of
work for a different pay.
Both the boss and the colleague have disregarded a
professional obligation and distorted the truth, putting an
uncountable amount of people at risk based on the success of
the product. The boss and colleague Z act of self-interest in
altering the data exposing the hazard of nanoparticles has put
the entire team at a reliable and possibly vulnerable
situation. Their self-serving goal has violated the
professional obligation to not let selfishness influence their
professional duty in engineering.
A chemical engineering code is that we should be
“Striving to increase the competence and prestige of the
engineering profession described in canon six [2].” In the
future when people find out the toxicity of our carbon
nanotube solar cells, we could make this field of engineering
receive extremely bad reputation, lose some of its overall
funding, all because of a mistake that would have been fixed
if I simply brought the issue to our attention and tried to ask
for more time to improve the carbon nanotubes being used,
even if it would mean possibly losing the funding of this
project and having to abandon.
Our test on the lab rats is also a company report that
can be used as a research item for this particular
nanoproduct. By having falsified results, we are not allowing
information that is “as accurate as possible [10]” along with
deceiving everyone in the company who was not involved in
the trickery. This type of carbon nanotube can be a prototype
to be modeled after, possibly producing even more toxic
nanotubes because other scientists and engineers have the
belief that this model is safe. Also, within the company,
rather than being ethical and self-regulatory [10], we have
put the company’s selfish needs as a priority. One of the
responsibilities of the company’s research facilities and the
general solar energy industry is protection reciprocity [10].
This cannot be done because we have allowed a faulty,
dangerous product that is likely to be discovered to be
hazardous and recalled, harming the industry’s overall
reputation and possibilities for growth.
Canon one states that an engineer must “Use their
knowledge and skill for the enhancement of human welfare
[2].” and the first rule of practice is to “hold paramount the
safety, health, and welfare of the public [1].” If I decide to
alert the authorities of the deceitful behavior of my
colleagues, I would maintain the precedence of keeping the
good of the general public secure and the utmost priority. I
would also uphold the professional obligation to protect the
environment and “serve the public interest [1],” rather than
allowing harmful agents into the environment and
completely undoing the benefits of the solar energy from
carbon nanotube solar cells.
Canon two states that engineers must only do the
work they competent and experienced in. Although
colleague Z and I have both performed separate statistical
analyses of the raw data of mice and carbon nanotubes
without being licensed statisticians, we have both taken
sufficient courses in statistics and are competent in
performing the analysis. Even if we were not legible to do
the analyses, they were for personal reasons to find out a
general idea of whether the project could succeed and the
final statistical report was still done by the statistician.
Canon three is also not used in this ethical scenario because
no public statements to the press had to be made. Thus these
two canons are not very useful in this situation.
POPULATIONS INVOLVED
The population included in the effect of the toxic
nanotubes is completely unpredictable in this situation. This
idea is known as penetrance, when the damage is completely
impossible to measure and all things in the ecosystem are
affected. There is also an unpredictability effect brought by
hazardous carbon nanotubes because no one can be sure
what the other effects/damages are and/or how the problem
will be able to be controlled [8].
We also do not know if there are “unforeseen risks
[9]” since the product we have developed in two weeks has
only been tested in the span of a few days. There could be a
plethora of other issues with this newly developed item and
it could even affect other parts of society that we would not
have expected. Since the discovery of carbon nanotubes,
there has been very little, yet much needed regulation of the
product. Even with further testing, there is the precautionary
principle, which states “threats in the future are forever
uncertain [9].”
Allowing people to be exposed to this radiation is
like forcing down people’s throats an unnecessary dosage of
harmful pills every day without their knowledge of it. If we
allowed the product to go with fake results and little
research, we will have created an inhumane experiment on
the general population to see they will react to this type of
carbon nanotube. This would go against all humane practices
in experimentation, taking away the choice to participate or
be.
If we decide to pull through with this product, this
type of carbon nanotube, along with any unregulated carbon
nanotube, will have adverse effects on many different
populations. The carcinogenic material will reach anyone
and everyone involved in the manufacture process when the
system is not isolated, researchers, people who clean the
production area, people who dispose of the waste products
and anyone exposed to accidental spillage. Besides this wide
bracket population, if this product is for everyday use, it can
be sold online by anyone who is interested in purchasing,
having anyone who is around them inhale this carcinogenic
product. However, it is not just for people completely
uninvolved with the carbon nanotubes, and they should have
the least exposure [6]. Yet, they might have equal exposure,
including high school and college students at research
facilities.
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Angela Chang
[2](2012) “Code of Ethics.” The Global Home of Chemical
Engineers.(online article) http://www.aiche.org/about/codeethics
FINAL DECISION
The best method that obeys the ethical code would
be to alert the authorities because the safety of the public
always takes the highest precedence in any given situation.
Although it would mean losing the funding to a competitor
company, it would not endanger a large set of people, and in
the end hurting the company’s reputation because of a small
group of peoples’ mistakes. With more time available, we
can find ways to perfect the carbon nanotube, test it, and
then bring it to the market. As this product and similar ones
becomes more in demand, the detriment will grow at an
exponential rate if radiation is not tested. We may not notice
anything wrong until years when people realize that this
product must be recalled because of its asbestos-like
properties. Therefore a utilitarian way of approaching such a
problem, if the carbon nanotubes did have any potential
dangers, is to find a way of isolating it, and still allow the
same abilities for usage. Coating the potentially toxic carbon
nanotubes with a plastic polymer like coating can reduce the
danger of exposure to asbestos like radiation [7]. This
method can be one of the many solutions towards promoting
worker safety and global environmental safety.
[3] Riskbites. “Carbon Nanotubes Risks - exposure,
chemistry and physical form” Online Video Clip. Youtube.
YouTube, 11 Mar. 2013. Web 26 Oct
2014. https://www.youtube.com/watch?v=lq_l09kxzh0
[4]Museum of Life and Science. “Are Carbon Nanotubes the
Next Asbestos?” Online Video Clip. Youtube. Youtube, 23
Feb. 2009. Web 26 Oct 2014.
https://www.youtube.com/watch?v=6L7xXgWcbrQ
[5]Anna Julie Rasmussen. (2014) “Characteristics,
Properties and Ethical Issues of Carbon Nanotubes in
Biomedical Applications.” Springer Science+Business
Media Dordrecht. (online article)
http://link.springer.com/article/10.1007/s11569-014-01879/fulltext.html
[6](2009) “Risk management of carbon nanotubes” Health
and Safety Executive. (online
article)http://www.steptoe.com/assets/htmldocuments/UK%
20HSE%20Risk%20Mgmt%20Carbon%20Nanotubes.pdf
[7] Tabet, Lyes.(2011) “Coating carbon nanotubes with a
polystyrene-based polymer protects against pulmonary
toxicity.” Particle and Fibre Toxicology.(online article)
http://www.particleandfibretoxicology.com/content/8/1/3
[8] Tuma, Julio R. (2009) “Nanoethics and the Breaching of
Boundaries:A Heuristic for Going from Encouragement to a
FullerIntegration of Ethical, Legal and Social Issues and
Science.” Springer Science & Business Media B.V.(online
article)
http://content.ebscohost.com/ContentServer.asp?T=P&P=A
N&K=69806578&S=R&D=aph&EbscoContent=dGJyMNH
r7ESeqLQ4zdnyOLCmr0yep7VSsK%2B4TLCWxWXS&C
ontentCustomer=dGJyMO7f8oy549%2BB7LHjgO3p8gAA
RECOMMENDATIONS TO ENGINEERS
What I have learned from my research on
nanoethics and from the engineering codes of conduct is that
the proper method of approaching an issue can be a
convoluted process because different canons and
responsibilities stated in the code can sometimes oppose one
another. As engineers, it is usually best to choose the canon
or responsibility that sounds the most ethical based on the
situation, and that will bring positive effects to the greatest
number of people possible. Also, it is advised that if self
interest may block ethical reasoning, then it is always right
to alert a supervisor or the rest of the team members to
stimulate group/community thought rather than self-thought
based on self interest. Often times, although the group’s goal
may not have been met, there can be a compromise such as
extra time to complete the project and vital ethical
responsibilities like product safety can be verified, making
the project an ethical success rather than a financial one.
[9] Rassmussen, Anna Julie. (2012) “Nanoethics—A
Collaboration Across Disciplines.” Springer
Science+Business Media Dordrecht.(online article)
http://ejournals.ebsco.com/Direct.asp?AccessToken=293129
S8SEZ2EXWEL93EYHAL29BX892S3&Show=Object
[10] “Ethics in Engineering.” Crystal Graphics. (Online
powerpoint presentation)
http://www.powershow.com/view/92741ZjQ4M/Ethics_in_Engineering_powerpoint_ppt_presentatio
n
REFERENCES
[1] (2007) “NSPE Code of Ethics for Engineers.” National
Society of Professional Engineers.(online article)
http://www.nspe.org/resources/ethics/code-ethics
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Angela Chang
[11] Kaydee. “Carbon Nanotubes and Cancer: A Hazard
Forestalled?” BlogSpot. Blogspot, 30 June 2008. Web 25
October 2014.
http://engineeringethicsblog.blogspot.com/2008/06/carbonnanotubes-and-cancer-hazard.html
[12] (2014) “ Carbon Nanotubes Are Superior To Metals
For Electronics, According to Engineers” University at
Buffalo. (online article).
http://www.sciencedaily.com/releases/2009/03/0903201340
41.htm
(2014)“ETHICS CASES” Texas Tech Center. (online
article)
http://www.depts.ttu.edu/murdoughcenter/products/cases.ph
p
[13] P.M. Bota. (2014) “Synthesis of single-wall carbon
nanotubes by excimer laser ablation.” Surface Engineering
and Applied Electrochemistry. (online article.)
http://link.springer.com/article/10.3103%2FS106837551404
005X
I would like to thank my Engineering Analysis professor,
Dr. R. Schaub, Professor Kirchner and Professor Faina for
writing assistance.
(2014) “Ethics Case Studies in Biodesign.” Stanford
Biodesign.
(online
article)
://www.biodesign.stanford.edu/bdn/resources/ethicscases.jsp
ACKNOWLEDGMENTS
[14] B. Dume. (2014) “Making better solar cells with
polychiral carbon nanotubes.” Physicsworld. (online article).
http://physicsworld.com/cws/article/news/2014/aug/15/maki
ng-better-solar-cells-with-polychiral-carbon-nanotubes
[15] M. Gong(2014) “Breakthrough for Carbon Nanotube
Solar Cells: Twice as efficient as current models.” Science
Daily. (online article)
http://www.sciencedaily.com/releases/2014/09/1409031058
41.htm
[16] J. Tan.(2012) “Photovoltaic effect of individual
polymer nanotube.” American Institute of Physics. (online
article)
http://scitation.aip.org/content/aip/journal/apl/100/17/10.106
3/1.4705373
[17] Alhoff, Fritz. (2007) “On the Autonomy and
Justification of Nanoethics.” Springer Science and Business
Media.
(online
article)
http://ejournals.ebsco.com/Direct.asp?AccessToken=8PUY4
P0V091U3J0OUFNY9W90JNT1VP90U&Show=Object
ADDITIONAL SOURCES
(2007) “NSPE Code of Ethics for Engineers.” National
Society of Professional Engineers.(online article)
http://www.nspe.org/sites/defualt/files/BER%20Case%20No
%2013-11-FINAL.pdf
(2014) “Cases and Scenarios” National Academy of
Sciences. (online article)
http://www.onlineethics.org/Resources/Cases.aspx
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