Transcript Document

Risk and Regulatory Issues Associated
with the Disposal of Nanomaterials
Stephen M. Beaulieu
Nanomedicine and Molecular Imaging Summit, January 31-February 1, 2010
SNM Midwinter Meeting – Albuquerque, NM
www.rti.org
phone 919-541-7425 • mobile 919-475-9474 • e-mail [email protected]
RTI International is a trade name
of Research Triangle Institute
Will regulations designed to deal with
disposal issues work for nanotechnology?
 In US, EPA has primary responsibility for safe and effective
disposal of materials and products at the end of the life cycle
 Two key EPA-administered laws that provide the regulatory
framework for end-of-life management strategies
1.
Resource Conservation and Recovery Act (RCRA)
2.
Comprehensive Environmental Response, Compensation and
Liability Act (CERCLA)
 Other laws such as the Clean Water Act (CWA) and Toxic
Substances Control Act (TSCA) also regulate the disposition
of chemicals
 In terms of “disposal,” however, RCRA is unquestionably the
most important regulatory authority that determines how
residuals are managed at the end of the life cycle
2
Why focus on RCRA?
 RCRA regulates the handling, reuse, recycling, storage,
treatment, and disposal of solid and hazardous wastes,
including medical wastes and mixed wastes
 Relatively little research on the environmental, health, and
safety issues associated with how NMs are managed as
waste residuals or spent products
 Recent studies suggest that the risk of release of NMs will be
highest during disposal, destruction, or recycling
(Breggin & Pendergass, 2007)
 RCRA requires EPA to characterize the risks to human
health and the environment associated with the management
of potentially hazardous wastes
3
How are management options determined for a
“new” chemical, waste, or material under RCRA?
Problem Formulation
Initial Data
Collection
Analysis
Review studies,
reports, etc.
Tier I – Hazard Characterization
Compare total conc Compare leach data
data to health/eco
to TC limits
A risk assessment is
conducted to determine
whether potential
management options
pose unacceptable risks
to human health and the
environment
Develop
Conceptual
Models
Risk Characterization
Evaluate completeness of
data vis a vis conceptual
models and life cycle
Potential
risk?
yes
Tier II – Screening Assessment
Secondary
Data
Collection
Decision
Interpretation
Develop exposure
scenarios and conduct
screening-level
modeling
Potential
risk?
Tier III – 3MRA Model Simulation
yes
Tertiary
Data
Collection
4
no
Develop exposure
scenarios and conduct
screening-level
modeling
no
What types of approaches are used in the initial
tiers of a risk assessment?
A simple Risk Assessment Matrix (RAM) approach is often used in the
initial tier 1 hazard characterization to focus on the agents (e.g., chemical,
biological) that are most likely to be of concern.
Severity
Likelihood
5
Catastrophic
Rare
(1)
Negligible
(2)
Marginal
(3)
Critical
(4)
Improbable
(1)
1
2
3
4
5
Remote
(2)
2
4
6
8
10
Occasional
(3)
3
6
9
12
15
Probable
(4)
4
8
12
16
20
Frequent
(5)
5
10
15
20
25
(5)
Why are modeling approaches often used in
higher level risk assessment tiers?
 Modeling allows us to develop quantitative insight into
different types of risk questions, to predict potential
health and environmental outcomes

What are future risks likely to be?

What are the most significant risks?

What are the critical risk factors?

What are the most effective risk reduction options?
 Importantly, modeling allows us to deal with data
limitations, uncertainties, and variability in exposure
and toxicological response
6
What are the basic data needs for predictive
quantitative risk assessments under RCRA?
 Partition coefficients
 Biodegradation rates
 Solubility
 Particle sizes
 Bioaccumulation factors
 Biotransfer factors
 Food ingestion rates
 Water consumption rates
 Meteorological data
 Soil characteristics
 Hydrogeologic regions
 Human health toxicity
 Ecological toxicity
7
Can existing risk assessment modeling tools
be used for NMs if data are available? (hint: no)
8
Are sufficient data available for any NM to
support quantitative risk assessment? (hint: no)
 In The known unknowns for nanomaterials: describing and
characterizing uncertainty within environmental, health, and
safety risks, Grieger, Hansen, and Baun (2009) make a
compelling case regarding NM data deficiencies
 Authors reviewed 31 recent reports and articles describing the
state-of-the-science with regard to NMs and risk assessment
 Methodology divided the uncertainties into four “locations”
including (1) Testing, (2) Characteristics of NM, (3) Exposure
Assessment, and (4) Effects Assessment
 Authors concluded that “Given these data, it is unclear if
quantitative risk estimates including most quantitative uncertainty
analyses are able to provide meaningful results.”
9
How can we think about risk assessment
given the uncertainties associated with NMs?
Perhaps we should focus on developing an answer to the question: “what
level of research and data are needed to develop a predictive tool that can
reliably be used to support waste management decisions under RCRA?”
Lower Cost
Simpler Models
Limited Data Requirements
Higher Uncertainty
10
Higher Cost
More Complex Models
Greater Data Requirements
Lower Uncertainty
How can we conceptualize NM risk
assessment in a meaningful way?
Perhaps we should draw on our previous RA experience to create a modeling
framework that provides useful (not perfect) information to support the
decision making process
Chemical-Physical
Properties
NM Release
NM Fate and
Transport
Predictive
Risk Model
NM Effects
Environmental Behavior
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Simulation
NM Exposure
Health and Ecological
Endpoints
Risk Estimates
DECISION
What about other regulatory entities that use
RA to support decision making?
 Under the CWA, the EPA regulates the management of an enormous
volume of sewage sludge (aka biosolids) that are treated and used as
a soil amendment for agricultural lands – same problems
 Under TSCA, the EPA has broad authority to regulate the
manufacture, use, distribution in commerce, and disposal of new and
existing chemical substances – same problems
 FDA is responsible for product safety and effectiveness, and the
Agency is a frequent user of risk assessment to address safety
concerns – same problems
 The NRC and DOE are responsible for regulating the radioactive
aspects of solid wastes, including wastes that contain nanomaterials
and radionuclides – same problems
Potential keys to the path forward for
assessing end-of-life risks?
 Most statutes (certainly RCRA), in their current form, contain
sufficient regulatory breadth to cover nanomaterials; however, some
changes will likely be needed to define the products and wastes in
terms of nanomaterial characteristics
 In the absence of reliable tools/data to perform predictive, quantitative
risk assessments, alternative approaches such as multi-criteria
decision analysis may provide a transparent method to determine the
most appropriate management option
 Other structured approaches to managing uncertainty in
environmental modeling may provide a sound basis for the
development of simple models that incorporate new research data as
it becomes available (e.g., Koprogge, van der Sluijs, and Peterson, 2009)
A few references of interest ….
14

Grieger, K.D., S.F. Hansen, and A. Baun (2009). The known unknowns for nanomaterials:
describing and characterizing uncertainty within environmental, health, and safety risks.
Nanotoxicology. 3:3.

Kloprogge, P., J.P. van der Sluijs, and A.C. Peterson (2009). A method for the analysis of
assumptions in model-based environmental assessments. Environmental Modelling and
Software. In press.

Breggin, L.K., and J. Pendergrass (2007). Where Does the Nano Go? End-of-Life Regulation of
Nanotechnologies. Project on Emerging Nanotechnologies, PEN 10, Woodrow Wilson
International Center for Scholars.

Refsgaard, J.C., J.P. van der Sluijs, A.L. Hojberg, and P.A. Vanrolleghem (2007). Uncertainty in
the environmental modelling process – A framework and guidance. Environmental Modelling
and Software. Vol. 22, pp 1543-1556.

Thomas, T., K. Thomas, N. Sadrieh, N. Savage, P. Adair, and R. Bronaugh (2006). Research
Strategies for Safety Evaluation of Nanomaterials, Part VII: Evaluating Consumer Exposure to
Nanoscale Materials. Toxicological Sciences. Vol. 91, No. 1, pp 14-19.

Walker, W.E., P. Harremoes, J. Rotmans, J.P. van der Sluijs, M.B.A. van Asselt, P. Janssen,
and M.P.Krayer von Krauss (2003). Defining Uncertainty: A Conceptual Basis for Uncertainty
Management in Model-Based Decision Support. Integrated Assessment. Vol. 4, No. 1, pp 5-17.