ISO/TR 18637:2016

TECHNICAL ISO/TR
REPORT 18637
First edition
2016-12-01
Nanotechnologies — Overview
of available frameworks for the
development of occupational
exposure limits and bands for nano-
objects and their aggregates and
agglomerates (NOAAs)
Nanotechnologies — Vue d’ensemble des cadres disponibles pour la
définition de limites et bandes d’exposition professionnelle applicables
aux nano-objets, à leurs agrégats et agglomérats (NOAA)
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 3
5 Description of available processes for setting OELs and OEBs . 5
5.1 General considerations . 5
5.2 Description of evidence-based process . 6
5.3 Substance-specific OELs . 8
5.4 Categorical OELs . 8
5.5 Initial or default occupational exposure bands . 9
6 Substance-specific OELs for nanomaterials .10
6.1 General overview .10
6.2 Available substance-specific OELs .10
6.2.1 Carbon nanotubes .10
6.2.2 Nanoscale TiO .
2 11
6.2.3 Fullerenes . .12
6.3 Evaluation of OEL methods .12
6.3.1 Similarities and differences .12
6.3.2 Influence of methods on derived OEL values for nanomaterials .13
6.3.3 State of the science in support of risk assessment methods for
nanomaterials OELs .14
7 Categorical OELs for nanomaterials .15
7.1 Summary of options proposed .15
7.1.1 United Kingdom .15
7.1.2 Germany .15
7.1.3 NIOSH .17
7.1.4 Japan’s (AIST’s) approaches .17
7.1.5 OECD . .18
7.2 Evaluation of categorical OEL .19
7.2.1 Similarities and differences .19
7.2.2 State of the science supporting categorical OELs .20
8 OEBs and control banding for nanomaterials .21
8.1 Overview of current hazard and control banding schemes .21
8.1.1 Comparison of hazard bands and OEBs as applied to inhaled NOAAs .22
8.1.2 ISO hazard banding scheme for NOAAs .25
8.2 Case studies on banding NOAAs .26
8.3 Evaluation of the evidence for initial (default) OEBs for categories of NOAAs .28
8.3.1 Categorical analyses and read-across .28
8.3.2 Utility of in vitro data in OEL/OEB development for NOAAs . .29
8.3.3 Options for deriving an OEL or OEB for NOAAs .30
9 Feasibility considerations in the OEL and OEB setting process .30
Annex A (informative) Standard processes for OEL setting .32
Bibliography .62
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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electrotechnical standardization.
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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
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The committee responsible for this document is ISO/TC 229, Nanotechnologies.
iv © ISO 2016 – All rights reserved

Introduction
Nano-objects and their aggregates and agglomerates (NOAAs) represent a subset of particulate materials
that can be dispersed in the air and can represent health risks via inhalation exposures. NOAAs include
structures with one, two or three external dimensions in the nanoscale from approximately 1 nm to
100 nm, which may be spheres, fibres, tubes and others as primary structures. NOAAs can consist of
individual primary structures in the nanoscale and aggregated or agglomerated structures, including
those with sizes larger than 100 nm. An aggregate comprises strongly bonded or fused particles
[1][2][3][4]
(structures). An agglomerate is a collection of weakly bound particles (structures) .
The purpose of this document is to describe a general framework for the development of occupational
exposure limits (OELs) or occupational exposure bands (OEBs) for individual NOAAs or categories of
NOAAs with different levels of available data. OELs and OEBs are important tools in the prevention
of occupational illness. OELs have a long history in industrial hygiene and are based on observations
of workers or studies of laboratory animals. OELs are established to minimize the likelihood of
[5][6]
adverse effects from exposure to potentially hazardous substances in the workplace . An OEL is
generally substance-specific (although sometimes generically expressed, such as dust). Sufficient data
to develop an OEL may not be available, especially for substances such as NOAAs used in emerging
technologies. To aid in hazard communication and exposure control decisions for substances without
[7][8][9]
OELs, hazard banding has been used for many years . Substances are assigned to a hazard band
based on limited toxicity data usually from animal studies. Hazard banding schemes typically consist of
qualitative bands ranging from low to high severity of effects. Thus, a hazard band represents a range of
potential toxicities for a particular substance or category of substances. Some hazard banding schemes
[10]
include associated OEBs . The term OEB is a general term for exposure concentration ranges used
in some hazard banding schemes that are related to the ranges of hazard potentials. In contrast to an
OEB, an exposure band is a range of potential concentrations of a substance (or category of substances)
to which workers may be exposed in a defined occupational scenario and which is based on factors
such as the amount of NOAA processed or used, the nature of the process, and the form of the NOAA
[3]
including dustiness . In control banding, the hazard band and the exposure band are combined to
determine the control band for any particular occupational scenario (e.g. ISO/TS 12901-2).
OELs and OEBs are part of an overall occupational safety and health (OSH) program and are not
intended to identify and address all safety and health risks associated with a specific process or task.
OELs and OEBs are intended to provide occupational safety and health professionals with a health
basis for assessing the effectiveness of exposure controls and other risk management practices. The
exposure assessment of nanomaterials including carbon nanomaterials [such as fullerene, graphene,
single-walled carbon nanotube (SWCNTs) and multi-walled carbon nanotube (MWCNTs)], metal oxides
(TiO , SiO , zinc oxide, iron oxide), and metals (silver and gold nanoparticles) remains a challenge in
2 2
the field of occupational hygiene, as there have been relatively few studies on the characterization of
workplace exposures to NOAA. Sampling and analytical methods that have the capabilities to accurately
measure nanomaterials are still under development. Most sampling devices that measure airborne
particle count concentra
...