Supplementary Information (SI)
Figure Legend
SI Figure 1: Panelists and discussants in the December 2013 symposium built on previous work to identify research priorities for
multiwalled carbon nanotube (MWCNT) risk assessment and management. The previously identified MWCNT research priorities are
depicted here schematically with more information on the comprehensive environmental assessment (CEA) process used to identify
the research priorities, and the priorities themselves, available in reports (RTI International 2012; U.S. EPA 2013). Briefly, areas in
red are considered the highest priorities for research that informs MWCNT risk assessment and management. Areas in yellow, orange
and green are respectively lower priority areas. The subset of high research priorities (i.e., areas in red) that panelists focused on in the
December 2013 symposium are listed in tables.
SI Tables
The following tables summarize information that experts presented in the December 2013 Society for Risk Analysis Symposium.
Topic-areas for each table correspond with areas that a separate group of experts identified as high research priorities for MWCNT
during the 2012 CEA (SI Figure 1). The second column of each table contains an example of the specific research questions that
experts identified during the 2012 CEA. Experts in the 2013 SRA Symposium used these questions as a starting point to discuss next
steps for MWCNT research; however, in some instances, symposium experts modified the questions developed in 2012 to reflect
their understanding or perspective of the topic area. Additional information on the development of the original questions is available
in summary reports (RTI International 2012; U.S. EPA 2013). Note that Columns 3 through 6 of each table contain examples
developed by panelists in preparation for the December 2013 SRA symposium. References included in Column 3 were identified as
relevant examples by Commentary authors as a resource for readers. As such, information in each table is not intended to be
comprehensive.
SI Table 1: Product Life Cycle Research for Multiwalled Carbon Nanotubes (MWCNTs): Product Manufacturing Release Rate
Research area
Key research questions
for MWCNT flame
retardants
What research related to
this question is currently
underway?
Who is doing that
research?
What are barriers
to initiating or
continuing
research related
to this question?
What incentives could
encourage more research
related to this question?
Product Life
Cycle
1. What is the step in
manufacturing that
poses the greatest
risk of release to the
environment?
Example products:
Academic and agency
research groups,
including:
Intellectual
property
Public-private partnerships
Product
Manufacturing–
Release Rate
2. What is the step in
manufacturing that
poses the greatest
risk of occupational
exposure?
 CNT nanocomposites,
epoxy, coatings, including
for brakes (Hirth et al.
2013; Schlagenhauf et al.
2012a; Schlagenhauf et
al. 2012b)
Example release processes:
 Abrasion, degradation
(Huang et al. 2012)
Example conditions/
settings:
 Manufacturing facilities
 Lab-simulated natural
environments (e.g.,
representative
temperatures, relative
humidities, ultraviolet
light) (Orlov et al. 2012)
Example analytical methods:
Detection method
development (Ulrich et al.
2012)
 University of Iowa
 University of Illinois
 State University of
New York at Stony
Brook
 U.S. Environmental
Protection Agency
 BASF: The Chemical
Company
 Centers for Disease
Control/ National
Institute of
Occupational Health
Swiss Federal
Institute for
Materials Testing
and Research/
Institute of
Environmental
Engineering, ETH
Zurich
Regulatory
uncertainty
Proprietary
information
Research dollars
and scientific
interest
Limitations in
current
instrumentation
Funded work on a specific
“project” basis that is relevant
to BOTH an academic or
agency researcher and a
developer/marketer (e.g.,
nanoproduct company)
Job opportunities
More industry consortia, or
similar, organizations that
provide research venues that
provide collaborative research
and reporting, which enhances
scientific robustness of
resulting data
Table 2: Environmental Transport, Transformation, and Fate Research for MWCNTs: Wastewater Persistence
Research Area
Key research
questions for
MWCNT flame
retardants
What research related to
this question is currently
underway?
Who is doing that
research?
What are barriers to
initiating or continuing
research related to this
question?
What incentives could
encourage more
research related to
this question?
Environmental
Transport,
Transformation, and
Fate:
Persistence in
Wastewater
1. How does the degree
of functionalization
and changes in
wastewater
treatment processes
affect the rate of
transformation?
Most research is centered on
ENM types other than CNTs
(Kiser et al. 2009)
 NIST group
Standards/methods for
conducting tests, and
applicability of available
methods
Finding interested
stakeholders
 Center for
Environmental
Implications of
Nanotechnology,
Duke University
(e.g., Wiesner
group)
Identifying key MWCNT or
environmental properties
that most affect fate and
transport, and relating
laboratory experiments to
real- world environmental
conditions
Standardized
methods/criteria
 EMPA (Swiss
Federal
Laboratories for
Materials Science
and Technology)
(e.g., Gottschalk
and Nowack
groups)
Techniques for detection
and analysis
2. What are the
transformation
byproducts from
MWCNT and
flame-resistant
fibers?
 Analytics for other ENM
types more straightforward
(Kaegi et al. 2011;
Lecoanet et al. 2004)
Most research is done by
government labs and
universities, focused on a very
small subset of the overall
topic (Gottschalk et al. 2009;
Nowack 2010)
Environmental media are
complex; lab tests tend to
simplify simulated systems so
they can be more well defined
(and controlled) (Chen et al.
2010)
 Arizona State
University (e.g.,
Westerhoff group)
 Johns Hopkins
University group
Interested stakeholders
Identifying applications
with potential releases
Identify and prioritize
key properties
Development of
reliable and costefficient detection and
analysis methods for
CNTs that have quick
turnaround times
Table 3: Human Exposure and Dose Research for MWCNTs: Occupational Inhalation and Absorption
Research Area
Key research questions for
MWCNT flame retardants
What research related
to this question is
currently underway?
Who is doing that
research?
What are barriers to
initiating or
continuing research
related to this
question?
What incentives
could encourage
more research
related to this
question?
Human exposure
1. What research has been
started to connect human
occupational exposures
and design of relevant
(dose-level) studies?
Occupational exposure
studies are growing
(Methner et al. 2009)
Government and academic
(and some private) research
organizations, such as:
Availability of
standardized
MWCNTs
 MWCNT
manufacturing and
applications
(Shvedova et al.
2003)
 Multi-metric
approach still needed
(Donaldson et al.
2006)
 NIOSH-West Virginia
University partnership
 NSF Centers
 Brown University,
 Oregon Nanoscience
and Microtechnologies
Institute (ONAMI)
-Netherlands
Organisation for
Applied Scientific
Research (TNO)
Demonstrating the
effect of design on
biological response:
safer design?
Occupational –
Inhalation
And
Toxicokinetics:
Human –
Absorption
2. What principles are being
evaluated to design safer
nanomaterials?
3. Are the metrics adequate
to characterize the
exposure/dose level?
Inhalation is a key
exposure route;
respirable fraction is a
main focus (Schulte et
al. 2010)
 Low-dose studies
 Better
characterization
studies
Private-public collaborators,
such as:
 European Chemical
Industry Council (CEFIC)
Long-range Research
Initiative (LRI) to develop
criteria for safe design
 NIOSH partnerships with
private companies to
translate or link (human)
exposure data to dose data
from animal bioassays
Lack of access to
occupational settings
Changes in MWCNT
properties along the
life cycle: yes, no, or
maybe?
Unknown significance
of agglomeration in
air
Removing (at least
reducing) uncertainty
for regulators
Linking occupational
exposure experience to
toxicology and risk
assessments for
accurate risk
characterization
Effective risk
management measures
Table 4a: Human Toxicity Research for MWCNT: Non-cancer health impacts
Research Area
Key research questions for
MWCNT flame retardants
What research related to this
question is currently
underway?
Who is doing that
research?
What are barriers
to initiating or
continuing research
related to this
question?
What incentives
could encourage
more research
related to this
question?
Human health
1. Conduct acute and chronic
rodent bioassay studies
after inhalational exposure
at relevant doses using
well-characterized material
Evaluation of dermal and eye
irritation and skin sensitization
due to carbon nanotubes (Ema et
al. 2011)
National Institute of
Advanced Science
and TechnologyJapan (e.g., Ema,
Nakanishi)
Identifying product
formulations,
including
physicochemical
properties of the
nano-product and
each component part
Establishment of
consortia groups
with pooled funds
available to conduct
consuming studies
Non-cancer
2. Perform experiments to test
impacts of exposure on
immune-compromised
individuals
Biocompatibility of
nanoparticles and nanotubes
(Parvinzadeh Gashti et al. 2012)
Acute pulmonary dose-response
to inhaled MWCNTs (Li et al.
2012; Porter et al. 2010)
Interaction between CNTs and
human cells (Tsuchiya et al.
2014)
Islamic Azad
University – Iran
(e.g., Gashti,
Almasian)
Beihang UniversityChina (e.g., Li) and
Tsinghua University
(e.g.,Cui)
NIOSH- U.S.: (e.g.,
Porter, Castranova)
Research dollars to
perform studies on
the nanoproduct over
dose and time and
include appropriate
controls
Venues to publicize
and present findings
as well as to
communicate to
nonscientific
community
Tokai UniversityJapan (e.g.,
Tsuchiya, Kimura)
NIEHS Nano
Consortium
a
In the December 2013 SRA Symposium, the presentation on MWCNT research related to human health focused on examples of ongoing work within one
particular research consortium rather than providing information specific to each column in Table 4. As such, examples in Table 4 were developed by
Commentary authors as a resource for readers.
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