Workplace exposure - Assessment of dermal exposure to nano-objects and their aggregates and agglomerates (NOAA) (ISO/TS 21623:2017)

ISO/TS 21623:2017 describes a systematic approach to assess potential occupational risks related to nano-objects and their agglomerates and aggregates (NOAA) arising from the production and use of nanomaterials and/or nano-enabled products. This approach provides guidance to identify exposure routes, exposed body parts and potential consequences of exposure with respect to skin uptake, local effects and inadvertent ingestion.
ISO/TS 21623:2017 also considers occupational use of products containing NOAA by professionals, e.g. beauticians applying personal care products, cosmetics or pharmaceuticals, but does not apply to deliberate or prescribed exposure to these products by consumers.
ISO/TS 21623:2017 is aimed at occupational hygienists, researchers and other safety professionals to assist recognition of potential dermal exposure and its potential consequences.

Exposition am Arbeitsplatz - Leitfaden zur Beurteilung der Hautbelastung durch Nano-Objekte sowie deren Aggregate und Agglomerate (NOAA) (ISO/TS 21623:2017)

Dieses Dokument beschreibt einen systematischen Ansatz bezüglich der Bewertung möglicher Risiken am Arbeitsplatz im Hinblick auf Nanoobjekte und deren Agglomerate und Aggregate (NOAA), die sich aus der Herstellung und Nutzung von Nanomaterialien und/oder nanobasierten Produkten ergeben. Dieser Ansatz bietet Leitlinien zur Bestimmung von Expositionswegen, der Exposition ausgesetzten Körperteilen und möglichen Auswirkungen der Exposition bezüglich der Aufnahme über die Haut, lokalen Effekten und der unbeabsichtigten Aufnahme.
In diesem Dokument wird auch die Nutzung von Produkten, die NOAA enthalten, am Arbeitsplatz durch Fachleute berücksichtigt, z. B. Kosmetiker, die Körperpflegeprodukte, Kosmetika oder Pharmazeutika aufbringen; diese gilt aber nicht für die freiwillige oder verschriebene Exposition gegenüber diesen Produkten seitens der Kunden.
Dieses Dokument gilt für hauptberufliche Hygieniker, Forscher und andere Sicherheitsfachleute und dient zur Unterstützung bei der Erkennung einer möglichen Hautbelastung sowie von deren möglichen Folgen.

Exposition sur les lieux de travail - Évaluation de l'exposition cutanée aux nano-objets et à leurs agrégats et agglomérats (NOAA) (ISO/TS 21623:2017)

Izpostavljenost na delovnem mestu - Ocena dermalne izpostavljenosti nanodelcem ter njihovim agregatom in aglomeratom (NOAA) (ISO/TS 21623:2017)

Ta tehnična specifikacija CEN opisuje sistematičen pristop za ocenjevanje potencialnih poklicnih tveganj zaradi nanodelcev ter njihovih aglomeratov in agregatov (NOAA), ki nastajajo pri proizvodnji in uporabi nanomaterialov in/ali izdelkov, ki jih omogoča nanotehnologija. Ta pristop zagotavlja smernice za ugotavljanje načinov izpostavljenosti, izpostavljenih delov telesa in morebitnih posledic izpostavljenosti v povezavi z vnosom prek kože, lokalnimi učinki in nenamernim zaužitjem.  Ta tehnična specifikacija upošteva tudi poklicno uporabo izdelkov za osebno nego, kozmetike in zdravil, ki jih omogoča nanotehnologija, ne zajema pa namerne ali predpisane izpostavljenosti tem izdelkom. Ta tehnična specifikacija je namenjena poklicnim higienikom, strokovnjakom s področja zdravja in varnosti ter raziskovalcem kot pomoč pri prepoznavanju in obvladovanju potencialnih tveganj.

General Information

Status
Published
Publication Date
06-Feb-2018
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
07-Feb-2018
Completion Date
07-Feb-2018

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SLOVENSKI STANDARD
SIST-TS CEN ISO/TS 21623:2018
01-julij-2018
Izpostavljenost na delovnem mestu - Ocena dermalne izpostavljenosti nanodelcem
ter njihovim agregatom in aglomeratom (NOAA) (ISO/TS 21623:2017)
Workplace exposure - Assessment of dermal exposure to nano-objects and their
aggregates and agglomerates (NOAA) (ISO/TS 21623:2017)

Exposition am Arbeitsplatz - Leitfaden zur Beurteilung der Hautbelastung durch Nano-

Objekte sowie deren Aggregate und Agglomerate (NOAA) (ISO/TS 21623:2017)

Exposition sur les lieux de travail - Évaluation de l'exposition cutanée aux nano-objets et

à leurs agrégats et agglomérats (NOAA) (ISO/TS 21623:2017)
Ta slovenski standard je istoveten z: CEN ISO/TS 21623:2018
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
SIST-TS CEN ISO/TS 21623:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS CEN ISO/TS 21623:2018
CEN ISO/TS 21623
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
February 2018
TECHNISCHE SPEZIFIKATION
ICS 13.040.30
English Version
Workplace exposure - Assessment of dermal exposure to
nano-objects and their aggregates and agglomerates
(NOAA) (ISO/TS 21623:2017)

Exposition sur les lieux de travail - Évaluation de Exposition am Arbeitsplatz - Leitfaden zur Beurteilung

l'exposition cutanée aux nano-objets et à leurs agrégats der dermalen Exposition an Nano-Objekten sowie

et agglomérats (NOAA) (ISO/TS 21623:2017) deren Aggregaten und Agglomeraten (NOAA) (ISO/TS

21623:2017)

This Technical Specification (CEN/TS) was approved by CEN on 6 October 2017 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to

submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS

available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in

parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 21623:2017 E

worldwide for CEN national Members.
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CEN ISO/TS 21623:2018 (E)
Contents Page

European Foreword ...................................................................................................................................................... 3

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SIST-TS CEN ISO/TS 21623:2018
CEN ISO/TS 21623:2018 (E)
European Foreword

This document (CEN ISO/TS 21623:2018) has been prepared by Technical Committee ISO/TC 146 " Air

quality " in collaboration with Technical Committee CEN/TC 137 “Assessment of workplace exposure to

chemical and biological agents” the secretariat of which is held by DIN.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

Endorsement notice

The text of ISO 21623:2018 has been approved by CEN as CEN ISO/TS 21623:2018 without any

modification.
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SIST-TS CEN ISO/TS 21623:2018
TECHNICAL ISO/TS
SPECIFICATION 21623
First edition
2017-11
Workplace exposure — Assessment
of dermal exposure to nano-
objects and their aggregates and
agglomerates (NOAA)
Exposition sur les lieux de travail — Évaluation de l'exposition
cutanée aux nano-objets et à leurs agrégats et agglomérats (NOAA)
Reference number
ISO/TS 21623:2017(E)
ISO 2017
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SIST-TS CEN ISO/TS 21623:2018
ISO/TS 21623:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
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ISO/TS 21623:2017(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Dermal exposure to NOAA — Evidence and exposure routes ................................................................................ 4

4.1 General ........................................................................................................................................................................................................... 4

4.2 Source domains ...................................................................................................................................................................................... 4

4.3 Exposure routes ..................................................................................................................................................................................... 5

5 Stepwise approach for assessment of dermal exposure to NOAA ..................................................................... 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 Step 1: Desk evaluation .................................................................................................................................................................... 7

5.2.1 Step 1A: Evaluation of toxicological hazard based on NOAA composition .................... 7

5.2.2 Step 1B: Screening for potential risks associated with dermal exposure to

insoluble (non-flexible) NOAA ............................................................................................................................. 8

5.2.3 Step 1C: Screening for potential risks associated with dermal exposure

based on job title ........................................................................................................................................... ................10

5.3 Step 2: Observation of potential for dermal exposure .......................................................................................11

5.4 Step 3: Additional observation of worker behaviour..........................................................................................11

5.5 Step 4: Quantification of NOAA ..............................................................................................................................................11

5.6 Step 5: Evaluation and review ................................................................................................................................................12

Annex A (informative) Industries associated with use of nanomaterials or nano-

enabled products ..............................................................................................................................................................................................13

Annex B (informative) How to determine skin disruption? ......................................................................................................16

Annex C (informative) DeRmal Exposure Assessment Method (DREAM) ...................................................................18

Annex D (informative) Inadvertent ingestion exposure ...............................................................................................................24

Annex E (informative) Exploring dermal exposure measurements of nanoparticles ....................................27

Bibliography .............................................................................................................................................................................................................................31

© ISO 2017 – All rights reserved iii
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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 on 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 the following

URL: www.iso.org/iso/foreword.html.

ISO/TS 21623 was prepared by the European Committee for Standardization (CEN) Technical Committee

CEN/TC 137, Assessment of workplace exposure to chemical and biological agents, in collaboration with

ISO Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2, Workplaces atmospheres, in

accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

iv © ISO 2017 – All rights reserved
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Introduction

Dermal exposure assessment explores the dynamic interaction between environmental contaminants

and the skin. In contrast to inhalation exposure assessment, the assessment of dermal exposure

requires a different set of exposure considerations. During the last decades, the body of knowledge with

regard to dermal exposure has expanded for many types of substances, which amongst others resulted

in publications for the evaluation of dermal exposure to chemical substances that can be found, for

example, in CEN/TR 15278, CEN/TS 15279, and ISO/TR 14294.

Currently, engineered/manufactured nanomaterials and nano-enabled products are produced and

used on a wide scale. Occupational skin exposure to these substances can have biological relevance

to human health. Potential adverse effects include local skin effects, systemic toxicity following skin

absorption/uptake and inadvertent ingestion through the hand-to-mouth pathway. This document

provides guidance for the evaluation of potential dermal exposure to manufactured nano-objects, their

agglomerates and aggregates (NOAA).

This document is a compilation of the results of a pre-normative research project, executed under

Mandate M/461 for standardization activities regarding nanotechnologies and nanomaterials as issued

by the European Commission. This pre-normative research gives an overview of the mechanisms of

occupational dermal exposure to nanoparticles or nano-enabled products. This includes potential

concomitant for intake or uptake. It is based on relevant evidence of exposure for identified job

titles. Part of the pre-normative research comprised experimental work on the skin penetration

of nanoparticles, transfer of nanoparticles from a surface to the skin, and exploratory work on the

[4]-[6]
feasibility to quantify dermal exposure to NOAA .
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TECHNICAL SPECIFICATION ISO/TS 21623:2017(E)
Workplace exposure — Assessment of dermal exposure to
nano-objects and their aggregates and agglomerates (NOAA)
1 Scope

This document describes a systematic approach to assess potential occupational risks related to

nano-objects and their agglomerates and aggregates (NOAA) arising from the production and use of

nanomaterials and/or nano-enabled products. This approach provides guidance to identify exposure

routes, exposed body parts and potential consequences of exposure with respect to skin uptake, local

effects and inadvertent ingestion.

This document also considers occupational use of products containing NOAA by professionals, e.g.

beauticians applying personal care products, cosmetics or pharmaceuticals, but does not apply to

deliberate or prescribed exposure to these products by consumers.

This document is aimed at occupational hygienists, researchers and other safety professionals to assist

recognition of potential dermal exposure and its potential consequences.
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.

EN 1540, Workplace exposure — Terminology
ISO 18158, Workplace air — Terminology
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 1540, ISO 18158 and the

following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
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/TS 80004-2:2015, 3.4]
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3.2
aggregate

particle comprising strongly bonded or fused particles where the resulting external surface area is

significantly smaller than the sum of surface areas of the individual components

Note 1 to entry: The forces holding an aggregate together are strong forces, for example, covalent or ionic bonds

or those resulting from sintering or complex physical entanglement, or otherwise combined former primary

particles.

Note 2 to entry: Aggregates are also termed secondary particles and the original source particles are termed

primary particles.
[SOURCE: ISO/TS 80004-2:2015, 3.5]
3.3
dermal contact volume

volume containing the mass of the agent that contacts the dermal exposure surface (3.7)

Note 1 to entry: This is equivalent to the volume of the skin contaminant layer and for practical reasons

represents the volume of the compartment where the mass of the substance is all contained.

[SOURCE: CEN/TR 15278:2006, 2.2, modified — Note 1 adapted]
3.4
dermal exposure concentration

dermal exposure mass (3.6) divided by the dermal contact volume (3.3) or the dermal exposure mass

divided by the mass contained in the skin contaminant layer

Note 1 to entry: Dermal exposure concentration is expressed in g/l or g/kg or other appropriate units as

necessary.
[SOURCE: CEN/TR 15278:2006, 2.4, modified — Note 1 adapted]
3.5
dermal exposure loading
dermal exposure mass (3.6) divided by the dermal exposure surface (3.7) area

Note 1 to entry: For practical reasons, it can be expressed as mass of agent in an exposed part of the skin

contaminant layer divided by the surface area of that part.
[SOURCE: CEN/TR 15278:2006, 2.5]
3.6
dermal exposure mass
mass of agent present in the dermal contact volume (3.3)

Note 1 to entry: For practical reasons, it is defined by the amount of agent in g present in the skin contaminant

layer, or other appropriate units as necessary.

Note 2 to entry: The outcome of the process of dermal exposure, i.e. the contact, can be expressed by different

parameters of exposure.
[SOURCE: CEN/TR 15278:2006, 2.6, modified — Note 1 adapted]
3.7
dermal exposure surface
skin surface area where an agent is present

Note 1 to entry: For practical reasons, this is represented by a two-dimensional representation of the skin

contaminant layer in cm .
[SOURCE: CEN/TR 15278:2006, 2.7]
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3.8
nanocomposite

solid comprising a mixture of two or more phase-separated materials, one or more being nanophase (3.13)

Note 1 to entry: Gaseous nanophases are excluded.

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]
3.9
nano-enabled
exhibiting function or performance only possible with nanotechnology

Note 1 to entry: Potential release of NOAA from nano-enabled products is considered relevant in view of dermal

exposure assessment.
[SOURCE: ISO/TS 80004-1:2015, 2.15, modified — Note 1 added]
3.10
nanomaterial

material with any external dimensions in the nanoscale or having internal structure or surface

structure in the nanoscale (3.14)
[SOURCE: ISO/TS 80004-1:2015, 2.4, modified — Notes 1 and 2 deleted]
3.11
nano-object

discrete piece of material with one, two or three external dimensions in the nanoscale (3.14)

Note 1 to entry: The second and third external dimensions are orthogonal to the first dimension and to each other.

[SOURCE: ISO/TS 80004-1:2015, 2.5]
3.12
nanoparticle

nano-object (3.11) with all external dimensions in the nanoscale (3.14) where the lengths of the longest

and the shortest axes of the nano-object do not differ significantly

Note 1 to entry: If the dimensions differ significantly (typically by more than three times), terms such as

nanofibre or nanoplate may be preferred to the term nanoparticle.
[SOURCE: ISO/TS 80004-2:2015, 4.4]
3.13
nanophase

physically or chemically distinct region or collective term for physically distinct regions of the same

kind in a material with the discrete regions having one, two or three dimensions in the nanoscale (3.14)

Note 1 to entry: Nano-objects embedded in another phase constitute a nanophase.
[SOURCE: ISO/TS 80004-4:2011, 2.12]
3.14
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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3.15
perioral region
perioral area
area surrounding the mouth
Note 1 to entry: See Reference [10].
3.16
skin contaminant layer compartment
SCL

three-dimensional compartment on top of the stratum corneum (SC) of the human skin where sebum

lipids, sweat and additional water from transepidermal water loss (TEWL) are present, including

products from cornification and unshed corneocytes
3.17
source domain

generation mechanism that determines particle emission characteristics for a particular life cycle stage

Note 1 to entry: Different mechanisms determine the emission rate, particle size distribution, source location

and transport of NOAA during the various life cycle stages (synthesis, downstream use, application or treatment

[11]
of products and end of life) .
4 Dermal exposure to NOAA — Evidence and exposure routes
4.1 General

The mechanisms of occupational dermal exposure and evidence for skin penetration and local skin

effects have been defined in this document.

The relevance of dermal exposure to NOAA outlined in this document considers the following outcomes:

a) potential for penetration and systemic effects;
b) absorption by the stratum corneum (SC) and potential for local (skin) effect;
c) inadvertent ingestion.
4.2 Source domains

A conceptual source-receptor framework suitable for nanomaterials and nano-enabled products has

been developed. This links the source domains concept, as developed for modelling occupational

[11]

inhalation exposure to NOAA with the conceptual framework for dermal exposure. The dermal

exposure framework describes the various pathways, underlying mechanisms, and potential

[12]
consequences for NOAA contamination of the skin .

The source domains (SD) reflect different mechanisms of release and consequently possible different

nature of released aerosols and are thus associated with the life cycle stages of NOAA.

— SD 1: During the production phase (synthesis) prior to harvesting the bulk material, point source

or fugitive emission, e.g. emissions from the reactor, leaks through seals and connections, and

incidental releases, can take place. In these cases, discrete nanoparticles and homogeneous and

inhomogeneous agglomerates will be formed.

— SD 2: During the manufacturing of products, the handling and transfer of bulk manufactured

nanomaterial powders with relatively low energy nanoparticles can be released, e.g. during

collection, harvesting, bagging/bag dumping/bag-emptying, dumping, scooping, weighing,

dispersion/compounding in composites, etc. However, the powders are already in agglomerated

stage and high shear forces are needed for deagglomeration. Therefore, the majority of the released

particles will be agglomerates.
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— SD 3: During further processing or in the use phase of a ready-to-use nano-product, release can be

expected during the relatively high-energy dispersion/application of

— solid, powdery or (liquid) intermediates containing highly concentrated (>25 %) nanoparticles,

e.g. pouring/injection moulding, (jet) milling, stirring/mixing. As higher shear forces can occur

during high energy dispersion, de-agglomeration can occur, and

— relatively low concentrated (<5 %) ready-to-use products, e.g. application of coatings or spraying

of solutions that can form nano-sized aerosols after evaporation of the liquid phase component,

usually of mixed composition.

— SD 4: During the use phase of a product or its end-of-life phase, activities resulting in fracturing and

abrasion of manufactured nanoparticles-enabled end products at work sites can result in release

of NOAA, e.g. a) low energy abrasion, manual sanding or b) high energy machining (e.g. sanding,

grinding, drilling, cutting, shredding, etc.). High temperature processes like burning are included.

In case of release, most likely multi-composed aerosols will be emitted, and in case of machining

also matrix-bound nanoparticles, whereas during thermal processes nanoparticles can also be

formed following nucleation and condensation of vapours.

Process conditions will determine the release process (i.e. mechanism, form, composition and level

of release) and together with handling the process of skin contamination (i.e. through direct contact,

deposition from the air compartment or transfer from contaminated surfaces). In addition, professional

use of personal care products can result in direct contact of the product with the skin. Transformation

(e.g. change in particle size distribution, agglomeration, etc. of the nanomaterial on the skin compared

to the release) can occur either directly by the exposure process or route (e.g. transfer or direct contact),

or during time of residence in the air compartment.

The level of exposure, either dermal exposure concentration, mass or surface area of exposed (body)

location(s) will be determined by the underlying processes of release and exposure. In addition,

the exposure time, characteristics of the substances and skin physiological conditions need to be

considered.
4.3 Exposure routes

Observational studies show that the most highly exposed body parts are the hands, and the

[13]-[15]

predominating exposure pathway is nanoparticle transfer from contaminated surfaces .

However, deposition of airborne aerosols or direct contact with products containing NOAA can also

contaminate other body parts (e.g. forearms and forehead). Laboratory experiments carried out

as part of the pre-normative research, showed that transfer efficiency for nano-size particles was

approximately 30 times higher than that of micron-size particles, and showed for each particle size that

the higher the log-transformed loading, the lower the transfer efficiency (after accounting for particle

[4][6]

size) . Location of the exposure is of particular interest, since both the thickness of the SC and the

density of the hair follicles varies substantially over body locations, which is an important parameter

[16]-[19]

with regard to potential penetration and local effects of nanoparticles through the skin . In

addition to skin physiology, skin conditions and time of contact, the actual contact site is also relevant

[20]
for potential inadvertent oral exposure due to hand-to-mouth contact .

Dermal exposure risk by industrial sector and job title are based on reported use of nanomaterials and

nano-enabled products (see Annex A). No indication on the level of dermal exposure can be extracted

from available information. However, based on the form of NOAA and nano-enabled products present

in the work environment and the type of activities performed by the worker, it is possible to have a

first indication of the potential for dermal exposure occurring at the workplace and the accompanying

potential risk.

Nanoparticles on the skin can penetrate SC reaching viable epidermis using different pathways:

a) through sweat glands and hair follicles, which is probably the most efficient way for penetration

and permeation of NOAA;
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b) the intercellular route, which is only possible for very small NOAA (<4 nm) or in damaged skin

condition;

c) the intracellular pathway is unlikely to be relevant for NOAA, but might be relevant for released

(metal) ions.

Present evidence suggests that only very small particles (<4 nm) can penetrate intact skin, whereas

insoluble, nonreactive particles with sizes >45 nm will not be absorbed by the intact skin. Penetration

...

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