Created By: Dean Marinchek Supervised By: Dr. Larry Miller
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Nanotechnology is the engineering and manipulation of materials
at the molecular level The dimension of nanomaterials are between 1
and 100 nanometers 1nm is 1 billionth of a meter A human hair is
50,000 nanometers in diameter
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Particles created at the nanoscale have different chemical and
physical properties than larger particles of the same material
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Carbon Nanotubes (CNTs) in particular have unique electrical,
mechanical, and thermal properties with a large potential in
electronics, aerospace, and many other industries. CNTs exist in
two forms, single-wall (SWCNTs) and multi-wall (MWCNTs)
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Due to the relatively new nature of nanotechnology, research is
still being conducted on the health hazards Two facts must be known
to determine if workers are at risk The type and concentration of
nanoparticles in the workplace The specific properties of the
nanoparticles that could potentially affect the body
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Workplace tasks that increase the risk of exposure Handling
powders of nanomaterials Maintenance on equipment and processes
used to produce or fabricate nanomaterials and the cleaning-up of
spills and waste material containing nanomaterials Cleaning of dust
collection systems used to capture nanoparticles Machining,
sanding, drilling, grinding, cutting, or other mechanical
disruptions of materials containing nanoparticles
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In lab animals, some nanoparticles reach blood, brain, and
other organs when inhaled This causes adverse effects such as
inflammation and fibrosis in the lungs and other organs Recent
studies have shown that size, surface area, surface chemistry,
solubility, and possibly shape all play a role in determining the
potential to cause harm
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Studies in workers exposed to aerosols of some manufactured or
incidental microscopic and nanoscale particles have reported
adverse lung effects including lung function decrements and
obstructive and fibrotic lung disease
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CNTs may contain metal catalysts as byproducts of their
production, which could contribute to their toxicity Regardless of
the process by which CNTs were synthesized and the types and
amounts of metals they contained, CNTs were capable of producing
inflammation, epithelioid granulomas (microscopic nodules),
fibrosis, and biochemical/toxicological changes in the lungs
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SWCNTs have been shown to produce adverse effects at mass doses
at which ultrafine carbon black did not produce adverse effects.
Both are carbon based but SWCNTs have a unique structure SWCNTs
were shown to be more toxic than quartz, which is considered a
serious occupational health hazard if it is chronically
inhaled
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MWCNTs have been shown to produce lung lesions similar to those
observed in studies with SWCNTs These results indicate that, if CNT
particulates reach the lung in sufficient quantity, they will
produce a toxic response
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These studies do not answer the important health risk question
of whether airborne CNT particles can reach the lungs, because in
all cases the CNTs were placed inside the lungs of animals, not
inhaled
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The lungs arent the only organ affected by CNTs Studying the
effects on mouse hearts, scientists found damage to the DNA, an
increase of plaque in the aortic area, and an increase of
atherosclerotic lesions in the brachiocephalic arteries
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The risk of nanotubes is often compared to that of asbestos
Exposure to asbestos is not the same exposure that could occur with
CNTs. According to Lance Criscuolo, president of Zyvex Performance
Materials, an Ohio- based company that uses CNTs, CNTs, once mixed
into a polymer matrix, are bound up and no longer releasable into
air or water.
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This means the workers in most concern are the ones actually
creating the CNTs and putting them into plastics The EPA is most
concerned with the fibrous, dry powder and less concerned with CNTs
that are integrated into polymer materials, said David Burton,
General Manager, Applied Sciences Inc.
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Criscuolo said Zyvex has done air monitoring studies throughout
the entire process. These studies were performed by a certified
company. They were not able to detect any significant amount of
CNTs in the airstream. This testing was also included in the
composite cutting and sanding area. This provides some solid
evidence that once CNTs are encapsulated within a resin system,
that they are not able to become free from that system.
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Inhalation This is the most common and most dangerous type of
exposure It has been determined that the factors that have a role
in pulmonary toxicity include, but are not limited to: particle
number and size distribution dose of particle to target tissue
surface treatment on particles
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the degree to which engineered nanoparticles
aggregate/agglomerate surface charge on particles particle shape
and/or electrostatic attraction potential method of particle
synthesis i.e., whether formed by gas phase or liquid phase
synthesis and post- synthetic modifications, which likely influence
aggregation behavior.
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Ingestion Nanoparticles may enter the gastrointestinal tract as
they are cleared from the upper respiratory tract and they appear
to pass through relatively quickly It is known that some
nanoparticles, specifically nanotubes and nanofibers, can undergo
surface oxidation and length shortening in presence of strong acid
conditions, so it is possible that the acidic gastric environment
will not only be unable to destroy the nanoparticles, but it may
functionalize and shorten the particles to a point that their
toxicological effect on the surrounding environment might change
drastically
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Dermal Some studies show that nanoparticles may penetrate the
skin due to their small size. This possibility is being
investigated
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Traditional industrial hygiene sampling methods can be used to
measure airborne nanoparticles Scientists are developing more
sensitive and specific sampling techniques
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Workers need the development of sensors that simultaneously
detect airborne nanoparticles and determine their potential to
generate reactive oxygen species- possibly providing early
indications of harm
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These materials are used in the production of the CNTs
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Employers should use engineering controls to reduce workers
exposure to nanoparticles Source enclosure Isolating the generation
source from the worker Local exhaust ventilation systems Exhaust
ventilation systems that use HEPA filters are effective in removing
nanoparticles (See next slide)
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Prevent food and beverages in workplaces where nanomaterials
are handled Its a good idea to systematically evaluate exposure to
ensure that control measures are working properly and that workers
are being provided the appropriate personal protective
equipment
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Existing U.S. regulations do not specifically address
nanomaterials The EPA apparently intends to designate CNT releases
into US waters as a significant new use, which would likely trigger
a major amount of additional compliance record- keeping for
companies For a specific examples of a protocol for handling of
nanotubes see: PROTOCOLS FOR HANDLING NANOTUBE COMPOSITES.doc
PROTOCOLS FOR HANDLING NANOTUBE COMPOSITES.doc C-nano Material
Safety Data Sheet.pdf
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EPA is issuing significant new use rules (SNURs) under section
5(a)(2) of the Toxic Substances Control Act (TSCA) for two chemical
substances which were the subject of Premanufacture Notices (PMNs).
The two chemical substances are identified generically as
multi-walled carbon nanotubes (MWCNT) (PMN P08177) and
single-walled carbon nanotubes (SWCNT) (PMN P08328). This action
requires persons who intend to manufacture, import, or process
either of these two chemical substances for a use that is
designated as a significant new use by this final rule to notify
EPA at least 90 days before commencing that activity. EPA believes
that this action is necessary because these chemical substances may
be hazardous to human health and the environment.
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Exclusions include: After they have been completely reacted
(cured); Incorporated or embedded into a polymer matrix that itself
has been reacted (cured); or, Embedded in a permanent solid polymer
form that is not intended to undergo further processing except for
mechanical processing.
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Personal Environmental Monitors can detect the amount of
nanomaterials in the air that a worker is exposed to This is
crucial in the production of nanomaterials Examples of PEMs
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Inhalation and ingestion protection can be provided by
respirators Must be(NIOSH)-approved air-purifying, tight- fitting
full-face respirator equipped with N100 filters) Ingestion
protection can be aided by frequent washing of the hands and
maintaining a clean work environment Dermal penetration can be
prevented by the use of nitrile gloves and full-coverage lab
coats
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Accidental spills of nanotubes are inevitable during their
production, and the massive use of nanotubes-based materials could
lead to increased environmental pollution Research is being
conducted to help aid in this situation Scientists have found that
CNTs deteriorate when exposed to the natural enzyme horseradish
peroxidase, also called HRP Once fully developed the method could
be administered as easily as chemical cleanups in todays labs
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The use of HEPA filtered vacuums and/or wet wiping techniques
should be use often to keep the workplace clean Workers must wash
hands frequently Setting up conforming hazardous waste management
practices is a good idea