nanotechnology and exposure: the pathway to a safe and ... · •carbon nanotubes 1 μg/m3 (2013)...

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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252525

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

Question?

Dr. Candace Tsai, Candace.Tsai@colostate.edu