nanotechnology and exposure: the pathway to a safe and ... · •carbon nanotubes 1 μg/m3 (2013)...
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Nanotechnology and Exposure:
The Pathway to a Safe and Healthy Environment
Professor Candace Tsai
Colorado State University
Bogotá, 14-15 FEB 2017
Nanotechnology and Nanomaterials
Engineered Nanoparticles- Intentional Materials
Carbon nanotubeCarbon black Titanium dioxide
20 nm
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Lee et al. ACS Nano 4(7) 2010
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Ref: Canada NanoPortal
Ref: Lowry, et al., ES&T, 2012, 46(13), 6893
•Nanomaterials is released and distributed into water and air
•Environmental transformations of nanomaterials cause complicated exposure and effect
•Iron oxide nanomaterials
•Carbon nanotubes (CNT)
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Use carbon nanotubes to remove microorganisms from large quantities of water quickly, provide drinking water for astronauts.
Ref: Nasa website
Nanomaterials use for water purification
Nanomaterials use in wastewater treatment
CNT Properties and Application
•High electrical conductivity
•High thermal conductivity
•Very high tensile strength
•Highly flexible
•High surface to volume ratio! …..and more7
flexible carbon
nanotube battery
CNTs expand epoxy
applications
Nanotube Textile
Nanoparticles at beach
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Ref: National Geographic, May 2015
Nanoparticles (Titanium dioxides, TiO2) used in sunscreens and other consumer products may harm marine creatures by disabling the defense mechanisms that protect their embryos.
Nanoparticles for newborn?
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Needle-like particles of hydroxyapatite found in infant formula by researchers. Westerhoff and Schoepf/ASU, CC BY-ND
•Drug delivery
•Inhalation, injection or ingestion
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Effect to fetus?
Exposure at Workplaces
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Pleura
Inhalation Exposure
From Respiratory Tract to Brain
Human Exposure CaseA chemist formulated polymers and coatings usually using silver ink particles. When she later began working with “nickel nanoparticle powder” weighed out and handled on a lab bench with no protective measures, she developed throat irritation, nasal congestion, post nasal drip, facial flushing, and…..
This incident triggered the company to make plans for “better control measures” for working with nickel nanoparticles.
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Ref: 2014, American J of Industrial Medicine, Journeay and Goldman
Some nanoparticles are potential carcinogens
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International Agency for Research on Cancer (IARC) classified
Multiwalled Carbon Nanotubes (MWCNT) type 7 and TiO2 as 2B carcinogens in 2014.
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CNT in children’s lung in Paris
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Ref: Kolosnjaj-Tabi, EBioMedicin, 2015
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Exposure Assessment
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Invisible Airborne Particles
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NanoaluminaNanoalumina particle 45 nm
100 nm
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TEM grid (diameter 3.05 mm),
Polycarbonate filter, 0.2µm
pore (diameter 25 mm)
Bottom support
Cassette base
Air stream
Pump
Sampling Technique
Tsai diffusion sampler (TDS)
o Operated at low flowrate of 0.3L/min.
o Collected nanoparticles on grid by Brownian motion.
o Analyze particles using SEM on filter and TEM on grid. 26
Exposure Control and Protection
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Laboratory fume hood
o Airflow pattern is the major issue to cause exposure.
o Nanoparticles behave like a gas.
o Proper controls are necessary and important.Publication: Tsai et al. JNR 2009; Tsai et al. Annals of Occu H, 2010; Tsai, JNR 2013.
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oExposure from manufacturing and cutting nanocomposites oControls to reduce exposureoMaterial property test
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Near-field, source
Far-field, 2nd port
Tsai et al., AAQR, 2008.Tsai et al., NANO, 2008.Ashter et al., Polymer Eng. Sci. J.,2009.Tsai et al., JNR , 2012
Air velocity at 2nd port, 0.74m away
from the enclosure open slot, was
reduced to 67 ft/min from 2400 ft/min.
Silverman equation
Lx
QxV
7.3)(
Hopper & Enclosure
Isolation Ventilation Filtration
2nd port
o Exposure studied at near field and far fieldo Isolation significantly reduced particle escape o Enclosure and modified airflow/air velocity controlled exposureo Emission during processing at 2nd port contain individual particle
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Protective Clothing?
Improve property of fabric fiber to peel off nanoparticle
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(c) (d)
(e) (f)
Tsai, S., Contamination and Release of Nanomaterials Associated with the Use of Personal Protective Clothing, Annals of Occupational Hygiene, 2015, 1-13
Polyester (c, d) and Tyvek (e, f) fabric contaminated with nanoalumina particles
Polyester fabric
Tyvek fabric
Regulations and Actions
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Ref: US EPA 2017
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Toxic Substance Control
Act (TSCA) reporting
Final rule for Chemical Substances When Manufactured or Processed as Nanoscale Materials
•US National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limits (REL)
• Carbon nanotubes 1 μg/m3 (2013)
• As measured by NIOSH 5040 (elemental carbon)
Based on Limit of Quantification (LOQ)
•UK British Standard Institute (BSI) Occupational Exposure Limit (OEL), Swiss Accident Insurance Funds, German Institute for Occupational Safety and Health• Carbon nanotube 0.01 fibers/cm3
• As measured by scanning or transmission electron microscopy SEM/TEM
•Japan OEL• 30 g/m3 for SWCNT, 80 g/m3 MWCNT
• Based on no observed effect levels (NOELs)
Active non-profit organizations
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•American Industrial Hygiene Association (AIHA), Nanotechnology Working Group
•Sustainable Nanotechnology Organization (SNO)
•GoodNanoGuide, https://nanohub.org/groups/gng