NanoRelease Developing Methods to Measure Release of Nanomaterials from Solid Matrices

NanoRelease

Developing Methods to Measure Release of Nanomaterials from Solid Matrices

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NanoRelease@ilsi.org www.riskscience.org

A multinational public private partnership with administrative support by the ILSI Research Foundation

NanoRelease “Consumer Products” Project Overview

Goals

• Identify best practices for measuring release at critical points of the life cycle of current products

• Use inter-laboratory testing to advance the state of science for release measurement

• Develop/refine methodologies and demonstrate transportability

• Work with Standard Development Organizations to develop standard methodologies for release

• Come to the point of “cross stakeholder agreed-to” methods on release detection and characterization for nanoparticles

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NanoRelease Consumer ProductsSteering Committee

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Co-Chair: Darrell Boverhof DowCo-Chair: Yasir Sultan Environment CanadaRichard Canady ILSI RFBill Kojola AFL-CIOJoAnne Shatkin CLF Carolyn Cairns Consumers UnionMichael Hansen Consumers UnionBernd Nowack EMPAShaun Clancy Evonik DegussaAndrew Atkinson Health CanadaLie Chen Health CanadaMyriam Hill Health CanadaChristopher Kingston NRC-Canada

John Monica Porter WrightDick Brouwer TNO Research GroupTreye Thomas US CPSCCathy Fehrenbacher US EPAPhil Sayre US EPARichard Zepp US EPAAleksandr Stefaniak US NIOSHCharles Geraci US NIOSHVladimir Murashov US NIOSH and WHOBarbara Karn US NSFDebra Kaiser US NISTJanet Carter US OSHA

NanoRelease@ilsi.org www.riskscience.org

Hazard 78%

Exposure 21%

Release 1%

- based on NCBI citations 2011

Within the 1%, there are very few of what is actually released from real-world uses

Where are we looking for risk information on nanomaterials now?

4Data/Graphic Source: Shaun Clancy

Initial literature review on “nanorelease” measurement methods

• www.ilsi.org/ResearchFoundation/Documents/NanoRelease%20Background%20Doc.pdf

• Many qualitative methods available to detect, characterize or measure nanomaterials under controlled conditions

• Quantification difficult and not routine

• Differentiation of engineered nanomaterial particles from nanoparticles of the composite generally not addressed

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A nanomaterial is NOT the chemistry and electron micrograph of a particle.

It is a set of continuous distributions.

%Coating

Size Aspect ratio

Composition

Pb As Hg Se Fe Sb yy xx

Surface adherentsNanoRelease@ilsi.org

“Neat” nanomaterialIn composite

In product

Released material

In exposure medium

Transformations Alter the Distributions

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The “Neat” nanomaterial in hazard studies is not what is released or what is in exposure media from uses

Multiple Paths Make Multiple OutcomesWhere is the toxic part?

What do we relate to the tox studies?

Released nanomaterial

Receptor population C

Receptor population B

Receptor population A

Soil

Water

Air

NanoRelease@ilsi.org 8

Release is the defining conditionRisk depends on what is released at specific points along the life cycle

Release conditions and pathways to receptor cause different and unpredictable exposures

Without labeling, we may never know how to measure the real exposure at the receptor

How do we measure release to assess the risk of the product?

To make progress we must focus on the release as the control point for understanding risk. Not the pristine

material in a controlled suspension.9

NanoRelease General Work Plan

• Phase 1: Nanomaterial/Scope Selection• The Consumer Products Steering Committee chose multi-

walled carbon nanotubes in polymer for the first evaluation

• Phase 2: Methods Evaluation• Expert Task Groups

• Compile & catalogue database of data/info

• White Papers

• State of the Science Document

• Workplan for Inter-laboratory Studies

• Phase 3: Inter-laboratory Studies

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Project Outputs

• Separate evaluations of methods, materials, life cycle release scenarios for potential uses of MWCNT in polymers

• State of the Science evaluation of release of MWCNT from polymers, including methods-needs

• Measurement methods development plan for release of MWCNT from polymer for key life cycle release scenarios

• Agreed-to methods to measure MWCNT release from current commercial uses in polymer composites

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The project will translate developing science of measurement of release of nanomaterials into – best practice

– infrastructure

– experience, and

– risk assessment confidence

This will aid – development of guidance for risk assessment and

management,

– safe development of products, and

– public confidence in the safe uses of the technology

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Phase 2 Methods Evaluation: MWCNTs in Polymer

• 3 Task Groups

– Compile & catalogue database of data/info

– White Papers (for publication & informing SOS)• TG1: Measurement Methods

• TG2: Materials

• TG3: Exposure/Release Scenarios

• June 21/22 2012 Workshop at CPSC in Bethesda, MD, US

– White paper presentations

– Draft State of Science and Methods Workplan sections

• State of the Science Team (SOST)

– An independent integrative document

• Inter-Laboratory Testing Group

– Begin to design and coordinate inter-laboratory testing13

Task Group 1: Measurement Methods

How can MWCNT release from polymers be measured?

• Co-chairs:

Debra Kaiser (US NIST),

Aleksandr Stefaniak (US NIOSH)

• 13 Experts from: NIOSH, NIST, US EPA, U. Mass, U. Vienna, CSIRO, U. Iowa, Lockheed Martin

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The Meaning of Release Measurement Release measurement has multiple components1) Choosing and modeling the release

– Life cycle: fabrication, use/wear, destruction, environmental degradation, incineration, recycling

– Air, water, dust– How to mimic the real world condition?

2) Sampling the release– Dispersion, statistics, etc

3) Analyzing the sample4) Reporting the necessary information

– Detection <==> Characterization (recursive: you need to define the nano-characteristic of interest in order to know if you have detected it)

– Integration of release measurement to pathway modeling, exposure assessment, and toxicity data…

– Informatics! (and interface to in silico modeling?!)15

Findings/Challenges• Complexity of considering measurement for multiple

forms of released material, the media into which it is released, and the time frame of interest (consider immediate exposure or further transformation in transport?).

• It is critical to tackle “problem formulation” first in order to select between detection, characterization, and quantitative vs. qualitative methods. What do you need to decide, and what data are possible to generate that can support the decision.

• Many possible methods to specifically detect and characterize released MWCNT/polymer material; however, except for simple mass and particle counts, none appear to be sufficiently selective and quantitative for specific MWCNT related exposure assessment now. 

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The materials released to a pathway can vary

Source: Wendel Wohlleben

The release scenarios affect what is released

Source: Wendel Wohlleben

• Co-chairs:

Christopher Kingston (NRC Canada),

Richard Zepp (US EPA)

• 16 Experts from: NRC, US EPA, NC State, Applied Nanotech, Nano-C, Dow, BASF, Environment Canada, Lockheed Martin, Arkema

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Task Group 2: Materials

How do MWCNTs in polymer behave/interact with regard to measurement of release?

Initial focus on 5 polymer typesTo limit scope to the most commercially relevant

applications of MWCNT, using expert opinion and review of market surveys the project initially focused review on MWCNT applications in:– Epoxy– Polycarbonate– Polyamide– Polyurethane– Polyethylene

Even with this limitation the scope of variation is tremendous.

However, the purpose of the review is to identify ranges of material characteristics that should be captured within the methods we develop, not be exhaustive in review.

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• There is tremendous variety in materials and uses, but very little data on actual or anticipated uses

• Factors considered in materials evaluation include UV exposure, changes in temperature, exposure to acids/ bases, mechanical stresses

• UV stabilizers, coatings, and MWCNT functionalization and load can have a large effect on MWCNT release

• “Pristine” polymer abrasion and/or degradation characteristics are informative but not necessarily indicative of MWCNT release from commercial articles

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Findings/Challenges

• Co-chairs:

Bernd Nowack (EMPA Switzerland),

Charles Geraci (NIOSH),

Dick Brouwer (TNO Research Group Q&S)

• 17 Experts from: EMPA, NIOSH, TNO, SafeWork Australia, Northeastern U., CLF Ventures, USEPA, Lockheed Martin, Bayer, Tech. U. of Dresden, BASF, CPSC, U. Duisburg-Essen

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Task Group 3: Exposure/Release Scenarios

What are the most likely MWCNTs-polymer release scenarios?

Scope limiting decisions for Life Cycle Assessment evaluations

• Release scenarios were selected to represent a range of situations– injection molding– mechanical stress during manufacturing, – sports equipment – electronics– non-abrasive outdoor use – small parts in automobiles – tires– end of life treatment (incineration/landfills)

• Life cycle evaluations beginning at master batch – We are not considering free MWCNT prior to polymer

compositing23

• Focus is release scenarios, but will discuss how findings relate to “risk relevant” exposure

• It is possible in some scenarios there is essentially zero release

• Polymer and scenario selections interact and will be considered in the evaluations (but the combinations are difficult to bound)

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There are many potential sources for initiation of an exposure pathway

Source: Bernd Nowack

Source: Bernd Nowack

The likelihood of release for a given stage of life cycle varies by use

• Low release potential for electronic component or car component uses in consumers hands

• Higher release during industrial fabrication (but controlled conditions, so exposure can be managed)

• Relatively low release potential in landfill due to binding

• Potentially higher release under recycling scenarios (but again, conditions can be controlled if the materials are known)

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• Knowledge of actual uses is limited, the material choice will matter, and theoretical combinations of materials with uses/scenarios are quite varied.

• Nonetheless, some general observations can be made based on the types of uses and the polymers

• For most uses evaluated, MWCNT release likelihood during “consumer” life cycle phase seems very low based on inaccessibility of the product (e.g., encased as a component in a car), so detection methods may be all that are needed (rather than spending resources on full characterization and quantification methods).

• Release during fabrication and recycling would be higher and may be worthy of release quantification methods development, for conditions where control of release and exposure is uncertain.

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Findings/Challenges

State of the Science Team (SOST)

• Integrate release measurement knowledge and the needs for methods development

– Andrew Maynard (University of Michigan, USA)

– Bernd Nowack (EMPA Swiss Federal Laboratories for Materials Science and Technology)

– Maria Doa (US Environmental Protection Agency)

– Richard Canady (ILSI Research Foundation)

– Shaun Clancy (Evonik Degussa)

– Stacey Harper (Oregon State University, USA)

– Wendel Wohlleben (BASF Chemical Company)

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Phase 3: Interlaboratory Testing(pilot phase beginning 2013)

• To enable improvements, standardization, and widespread use of methods

• Interlaboratory Testing Group (ITG)– Co-chairs: Janet Carter (US OSHA), Carolyn Cairns

(Consumers Union)

– ~20 Experts: OSHA, Consumers Union, CSIRO, NRC Canada, U. Iowa, NIST, US Army, U. Mass, Bayer, NERL, BASF, US EPA

– Build from TG & SOS reports to create testing workplan

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• Phase 3 Testing: ― Multi-lab participation to test methods with highest potential― Use “round-robin” approach

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Plan for Phase 3 Inter-laboratory Methods Development (beginning 2013)

International Public Private Partnership• The NanoRelease platform

– Established for over 2 years,

– Methods for measuring release of carbon nanotubes in polymer matrices, now starting on food additives.

– Over 80 experts active from industry, NGO, government, academia in US, Canada, Europe, Australia, and more

• Funding is ~50/50 private/public

– Pew Charitable Trusts, Health Canada, Environment Canada, US EPA, US FDA, American Chemistry Council, ILSI North America, Nanotechnology Industries Association, Institute for Food Safety and Health, and more.

NanoRelease@ilsi.org

www.riskscience.org Thank you

Sponsors• US Environmental Protection Agency, Office of

Research and Development

• Environment Canada, Emerging Priorities Division

• Health Canada, New Substances Assessment and Control Bureau

• American Chemistry Council, Nanotechnology Panel

• Society of Chemical Manufacturers & Affiliates

• National Institute of Standards and Technology

• The Adhesive and Sealant Council

• American Cleaning Institute32