ISO/TR 22293:2021

TECHNICAL ISO/TR
REPORT 22293
First edition
Evaluation of methods for assessing
the release of nanomaterials from
commercial, nanomaterial-containing
polymer composites
Évaluation des méthodes de détermination d'émission de
nanomatériaux par des polymères composites commerciaux,
contenant des nanomatériaux
PROOF/ÉPREUVE
Reference number
ISO/TR 22293:2021(E)
©
ISO 2021

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ISO/TR 22293:2021(E)

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Published in Switzerland
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Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviations. 3
5 Understanding the nano-enabled products . 4
5.1 Pathway analysis for the supply chain . 4
5.2 Matrix and MNM characteristics affecting rate and form of release. 8
5.2.1 General. 8
5.2.2 Consideration of the polymer used in the composite . 9
5.2.3 Polymer degradation .10
5.2.4 Consideration of MNM used in the composite .10
5.2.5 Polymer nanocomposites .11
5.2.6 Application areas and use phase (or lifecycle) processes .12
6 Factors affecting release measurement method selection .15
6.1 General .15
6.2 Forms of release .16
6.3 Decision support framework to determine which transformations need
consideration with examples .21
7 Approaches to detecting and quantifying the released material associated with
added manufactured nanomaterials .23
7.1 General .23
7.2 Methods for sampling released material .23
7.2.1 General.23
7.2.2 Sampling material released into air .24
7.2.3 Sampling material released into water, solids, and biological fluids .25
7.3 Methods for preparing samples of released material for subsequent analysis .26
7.3.1 General.26
7.3.2 Preparation and analysis of air samples .26
7.3.3 Preparation and analysis of waters, solids and biological fluid samples .27
7.4 Measurement challenges .28
7.4.1 General.28
7.4.2 Surface functionalization and transformations.28
7.4.3 Sample collection artefacts .29
7.4.4 Applicability of a measurement method for a given release media .29
7.4.5 Sample preparation artefacts.29
7.4.6 Capability of a measurement method .29
7.4.7 Representativeness of measurements .30
7.4.8 Composition measurements .30
7.4.9 Polymer stability .30
7.4.10 Commercial practices .30
7.5 Considerations for detection, quantification, and determination of properties of
released materials .31
7.6 Applicable measurement methods .32
8 Identification of needs for standards, methods, instrumentation, decision
frameworks, and research .32
8.1 General .32
8.2 Potential improved/new methods .32
8.3 Inter-laboratory studies .33
8.4 Protocols and assays .34
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8.5 Opportunities for standardization of methods .34
8.6 Decision frameworks .35
Annex A (informative) Example case studies.38
Bibliography .57
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Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 229, Nanotechnologies.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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Introduction
0.1 General
The use of manufactured nanomaterials (MNM) in consumer products and applications is growing as
manufacturers exploit the unique properties of nanomaterials. MNMs are an increasingly common
feature of a growing variety of commercial applications and consumer products — from computer chips
to golf clubs. So too are concerns over what is or can be released from products containing MNMs, and
the risk and potential impacts of exposure to such releases. These unique properties offer significant
commercial value, enabling the manufacture of products that that offer novel characteristics. The MNM
might be embedded in solids, might be suspended in fluid, or might be bound to the surface of solid
products. An understanding of what is released from products containing MNMs is critical to planning
and managing safe development and use of those products.
This document aims to contribute to that understanding by providing a guide to the information to
be taken into account in determining the methods for identifying and evaluating releases of MNMs
from matrices; providing a framework for understanding how these methods and the information they
produce can support decision-making; and identifying opportunities for developing standards in this
area.
This document provides practical support for decisions related to product development and use through
early consideration of the potential for release of MNM and through focus on realistic use scenarios
where exposures to the released MNM might occur.
The intended users of this document would include:
— those planning to develop or adapt technical specifications for MNM use in commercial products;
— risk managers, product developers, exposure measurement practitioners or other stakeholders
seeking guidance on the availability and utility of methods to measure releases that could occur
from uses of specific MNMs in composites;
— methods and instrumentation developers seeking to identify needs of the risk management
community;
— those planning basic and applied research programs for measurement and modelling to support
decisions around sustainably safe uses of MNMs.
The structured review of the information regarding the selection of MNM measurement methods
provided in this document is needed because technologies to produce MNMs, their uses, and MNM
measurement methods are often developing at the same time, and the development of measurement
methods can in some cases lag behind product development needs. Furthermore, the need to measure
particular characteristics of the released MNM might also evolve as greater understanding of what
might cause toxicity for a particular kind of MNM is gained. This relationship between emerging
measurement methods and emerging information about toxicity makes a structured approach to review
of measurement needs even more important, so that data are assembled to support decisions using the
most up-to-date and fit-to-purpose measurement methods. Finally, the selection process for choosing
a particular MNM-composite for a product should include the consideration of whether the available
measurement methods are feasible for the evaluating the conditions of use of that MNM-composite.
This consideration is needed because many methods available for research or for controlled conditions
in industrial hygiene settings are not useful for realistic measurement needs where consumers might
be exposed. In some cases, those methods are too difficult to conduct outside of the laboratory, and in
other cases the methods are too labour-intensive to be feasible for routine decision support.
The development of the decision-making framework presented in this document is based in large part
on initial analyses that focused on releases from polyamide or epoxy polymers to which multi-wall
carbon nanotubes (MWCNT) have been added. Nonetheless, the framework can be used to inform the
selection of methods for identifying and evaluating the releases for a wide range of MNMs and types of
matrices, as illustrated by the case studies in Annex A. The case studies have been chosen because of
the availability of information and methods relevant for actual MNM-polymer composite uses.
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Release from polymer nanocomposites can occur through processes such as physical, chemical, or
thermal degradation of a polymer matrix, resulting in particles that might include a mixture of free
MNM, free polymer, and matrix-bound MNM. This document focuses on the first release to human
exposure or to an effluent pathway. While acknowledging that subsequent MNM fate and transport
could follow from this initial release, the primary concern of this document is whether and where
release of MNMs can occur in the context of consumer or commercial use, and the need to monitor
likelihood of human exposure potential. Although other stages of the lifecycle of products containing
MNMs are discussed briefly to provide context, subsequent fate and transport events are not addressed
in detail.
The ultimate goal is to use the report structure of this document as a foundation for addressing releases
of other MNMs from other matrices in subsequent versions of the document.
0.2 Decision-Making Framework
0.2.1 General
In developing the decision-making framework set out in this document two key concepts that have
proven useful in addressing the relevant risk management issues in support of decision-making have
[1]
been applied. The first is “problem formulation” . This describes the purpose and context of the
analysis, and the nature of the decision that the analysis aims to support. By making it clear the analysis
is being conducted to support a specific decision, this approach helps to ensure the analysis remains
focused on methods that have practical application in making that decision. The second key concept
is “fit for purpose.” In other words, the nature of the analytical approach used should be sufficient for
and appropriate to addressing the specific risk management decision. This includes assuring that the
depth of analysis - including consideration of the sources and potential magnitude of uncertainty – is
consistent with the information needed to support the decision. In the context of this document, this
means that feasibility is an important consideration in the choice of analytical methods.
0.2.2 Application of concepts
In applying these concepts to the selection of methods for identifying and evaluating releases of
MNMs from matrices, the problem formulation would include an evaluation of the potential for human
exposure to the component of the nano-enabled product (NEP) that contains the MNM and the potential
for MNM release from that component.
To evaluate the potential for human exposure, an understanding of the product design and the potential
use scenarios is required. If, for example, the component containing the MNM is fully encased within a
consumer product, or is part of a machine where it is accessible only during maintenance, there are
limited opportunities for human exposure as part of the release event. Description of potential use
scenarios is also critical for understanding the potential nature of human exposure (e.g. direct dermal
contact vs. inhalation of released MNM), as well as relevant conditions of potential wear and aging (e.g.
potential and nature of abrasion, temperature, presence or absence of water and UV light).
Together, these elements of the problem formulation can aid in determining which potential release
scenarios need to be tested, as well as the nature of the analytical methods needed and, thus, aid in
determining whether it is feasible to evaluate the risk of a given choice of product composition without
substantial investment in analytical methods development.
0.2.3 Tiered approach
In some situations, a tiered approach — such as those described in Clause 8 — can be useful. For
example, if release outside of a confined structure is not expected (e.g. if the MNM is contained within
a phone, and release would not result in consumer exposure), an analytical method that simply detects
the MNM could be sufficient. In other cases, a qualitative description might be useful to predict the
potential for further interactions with other materials, and ultimately the fate and transport of the
MNM. Such information could be used, for example, in deciding between alternative designs or products
0.2.4 Quantitative risk assessment presents challenges
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Finally, in some cases it could be necessary to quantitatively evaluate the MNM release in order to feed
into a quantitative risk assessment. In such cases, it is important to ensure that exposure measurements
are made in a way that facilitates integration with hazard data to evaluate risk. Such integration
includes evaluating the MNM characteristics with regard to key determinants of toxicity (e.g. degree of
aggregation and functionalization), and reporting exposure in relevant dose units. Currently completing
an evaluation of this kind presents a significant challenge, as the key determinants of toxicity and
appropriate dose units are still being identified in many situations.
0.2.5 Data requirements
As described in this document, key data needs to support a decision related to product development
and use include:
— a description of the NEP and where in the product the MNM is found;
— a description of common use scenarios, including frequency of use and relevant populations;
— a description of potential degradation mechanisms that can lead to release under the use scenario(s)
of interest;
— a description of the nanomaterial;
— a description of the composite matrix and its resistance to degradation under the use scenario(s) of
interest.
Based on this information, the assessor can determine the potential for release (including the release
rate) and the likely media into which the release might occur. These parameters in turn inform the
nature of sampling and analytic methods that might be needed.
0.3 Document structure and use
After a brief discussion of how the topic of this document relates to Lifecycle analysis, the document
addresses the structure of the polymer and the embedded MNM, and how those structures inform
measurement methods needs through their effect on the release rate and the form of the release
(Clause 5). Clause 6 describes how the relative resilience of the polymer matrix and the embedded MNM
inform measurement methods needs through their effect on the nature of the resulting release and
proposes a tiered (stepwise) decision framework for deciding if or which transformations at the release
point need to be considered. Worked examples applying the decision framework outlined in 6.3 are
presented in Annex A. Clause 7 addresses methods for measuring and describing the characteristics of
the released material, including sampling methods in various media, methods for sample preparation
and analysis, and measurement challenges. Clause 8 addresses remaining gaps and data needs, and
briefly reviews several available decision frameworks to support risk managers in determining the
information and sampling methods needed to support product design and development decisions.
It is anticipated that the information presented in this document will find application in assisting
manufacturers and regulatory agencies to more clearly identify products and scenarios with low
consumer exposure potential (e.g. where the MNM is part of a component that is fully encased) and
those products and scenarios with higher exposure potential (e.g. the MNM is in continuous contact
with human skin or is used under conditions subject to severe weathering). This document is also
intended to aid in evaluating — at the product design stage — how variation in adducts, coatings, or
MNM composition would affect MNM release rates and measurement needs.
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TECHNICAL REPORT ISO/TR 22293:2021(E)
Evaluation of methods for assessing the release of
nanomaterials from commercial, nanomaterial-containing
polymer composites
1 Scope
This document reviews and evaluates the utility of available methods to assess material released from
commercial polymer composites in support of product use and safety decisions, and describes what
revised or additional methods are needed. The document is not focused on describing methods per
se; rather the goal is to describe information that is appropriate for consideration in the selection of
methods to support decision-making.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/TS 80004 (all parts), Nanotechnologies — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TS 80004 (all parts) and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
manufactured nanomaterial
MNM
nanomaterial intentionally produced to have selected properties or composition
[SOURCE: ISO/TS 80004-1:2015, 2.9]
3.2
nanocomposite
solid comprising a mixture of two or more phase-separated materials, one or more being nanophase
Note 1 to entry: Gaseous nanophases are excluded [they are covered by nanoporous material].
Note 2 to entry: Materials with nanoscale phases formed by precipitation alone are not considered to be
nanocomposite materials.
[SOURCE: ISO/TS 80004-4:2011, 3.2]
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3.3
carbon nanotube
CNT
nanotube composed of carbon
Note 1 to entry: Carbon nanotubes usually consist of curved graphene layers, including single-wall carbon
nanotubes and multiwall carbon nanotubes.
[SOURCE: ISO/TS 80004-3:2010, 4.3]
3.4
multi-wall carbon nanotube
MWCNT
carbon nanotube composed of nested, concentric or near-concentric graphene sheets with interlayer
distance similar to those of graphite
Note 1 to entry: The structure is normally considered to be many single-wall carbon nanotubes nesting each
other, and would be cylindrical for small diameters but tends to have a polygonal cross-section as the diameter
increases.
[SOURCE: ISO/TS 80004-3:2010, 4.6]
3.5
lifecycle
consecutive and interlinked stages of a product system, from raw material acquisition or generation
from natural resources to final disposal
[SOURCE: ISO 14044:2006, 3.1, modified — the term has been modified from "life cycle" to "lifecycle".]
3.6
nano-enabled
exhibiting function or performance only possible with nanotechnology
[SOURCE: ISO/TS 80004-1:2015, 2.15]
3.7
single wall carbon nanotube
SWCNT
carbon nanotube consisting of a single cylindrical graphene layer
Note 1 to entry: The structure can be visualized as a graphene sheet rolled into a cylindrical honeycomb
structure.
[SOURCE: ISO/TS 80004-3:2010, 4.4]
3.8
nano-enhanced
exhibiting function or performance intensified or improved by nanotechnology
[SOURCE: ISO/TS 80004-1:2015, 2.16]
3.9
nanoscale
length range approximately from 1 nm to 100 nm
Note 1 to entry: Properties that are not extrapolations from larger sizes are predominantly exhibited in this
length range.
[SOURCE: ISO/TS 80004-1:2015, 2.1]
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3.10
agglomerate
collection of weakly or medium strongly bound particles where the resulting external surface area is
similar to the sum of the surface areas of the individual components
Note 1 to entry: The forces holding an agglomerate together are weak forces, for example van der Waals forces or
simple physical entanglement.
Note 2 to entry: Agglomerates are also termed secondary particles and the original source particles are termed
primary particles.
[SOURCE: ISO 26824:2013, 1.2]
3.11
graphene oxide
GO
chemically modified graphene prepared by the oxidation of graphite causing extensive oxidative
modification of the basal plane
[SOURCE: ISO/TS 80004-13:2017, 3.1.2.13, modified — "and exfoliation" has been deleted.]
3.12
additive
substance added to polymers to improve or modify one or
...