ISO/TS 11796:2023
(Main)Biological evaluation of medical devices — Requirements for interlaboratory studies to demonstrate the applicability of validated in vitro methods to assess the skin sensitization of medical devices
Biological evaluation of medical devices — Requirements for interlaboratory studies to demonstrate the applicability of validated in vitro methods to assess the skin sensitization of medical devices
This document specifies the framework and the methodology to evaluate and demonstrate the applicability of a validated non-animal method from an OECD test guideline to assess the skin sensitizing potential of a medical device or a medical device material. This document addresses: — the database of reference chemical skin sensitizers and non-skin sensitizers; — reference materials; — feasibility testing of candidate test methods, including any method optimization for use with extracts of medical devices; — prevalidation of candidate test methods; — the interlaboratory study: — sample preparation and coding; — spiking of the extracts from the negative control medical device material; — data collection; — statistical analysis to assess reliability and reproducibility. The use of the approaches described in this document to assess the applicability of a candidate test method does not imply that the candidate test method can be used as a stand-alone test for evaluating the skin sensitization potential of medical devices. For certain candidate test methods, integrated approaches and/or defined approaches are needed.[1] The evaluation of skin sensitization potential of a medical device is described in ISO 10993-10.
Évaluation biologique des dispositifs médicaux — Guide pour les études interlaboratoires visant à démontrer l'applicabilité des méthodes in-vitro validées pour évaluer la sensibilisation cutanée des dispositifs médicaux
General Information
Buy Standard
Standards Content (Sample)
TECHNICAL ISO/TS
SPECIFICATION 11796
First edition
2023-07
Biological evaluation of medical
devices — Requirements for
interlaboratory studies to
demonstrate the applicability of
validated in vitro methods to assess
the skin sensitization of medical
devices
Évaluation biologique des dispositifs médicaux — Guide pour les
études interlaboratoires visant à démontrer l'applicabilité des
méthodes in-vitro validées pour évaluer la sensibilisation cutanée des
dispositifs médicaux
Reference number
ISO/TS 11796:2023(E)
© ISO 2023
---------------------- Page: 1 ----------------------
ISO/TS 11796:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO 2023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 11796:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Consideration on the process for demonstration of the applicability domain .3
5 Positive and negative control test samples . 4
5.1 General . 4
5.2 Database of reference chemicals . 5
5.3 Reference materials . 8
5.3.1 General . 8
5.3.2 Negative control medical device material . 8
5.3.3 Positive reference material . 8
6 Preparation of the test samples .9
6.1 General . 9
6.2 Preparation of the extracts . 9
6.3 Spiking of the extracts . 9
7 Prevalidation of candidate test methods .10
8 Interlaboratory study .10
8.1 General . 10
8.2 Study organization . 10
8.2.1 General . 10
8.2.2 Management team . 11
8.2.3 Lead laboratory . 11
8.2.4 Sample management . 11
8.2.5 Independent biostatistician . 11
8.3 Sample preparation . 11
8.4 Performance review .12
9 Statistical analysis .12
10 Test report .12
Annex A (normative) Reference chemicals .14
Bibliography .29
iii
© ISO 2023 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/TS 11796:2023(E)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
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 194, Biological and clinical evaluation of
medical devices.
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.
iv
© ISO 2023 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TS 11796:2023(E)
Introduction
International Standards can be used to demonstrate the safety and compliance of medical devices.
ISO 10993-10 specifies the procedure for the assessment of medical devices and their constituent
materials with regard to their potential to induce skin sensitization (Type IV hypersensitivity reaction).
The methods included in ISO 10993-10 are based on animal or human testing, with an annex on in vitro
and in chemico tests for skin sensitization that have been validated for neat chemicals. The effort to
reduce or replace the use of animals in toxicity testing has led to the development of many new non-
animal methods. The test guidelines in References [56] and [57] include alternatives to animal testing
methods for skin sensitization that have been previously validated to confirm their equivalence/
superiority to the current in vivo methods. However, currently, none of the OECD test guideline methods
are considered sufficient stand-alone replacements for in vivo tests that assess the skin sensitization
[1]
potential of chemicals .
Current OECD test guideline methods are validated with neat chemicals and not with more complex
mixtures such as medical devices or medical devices extracts. In order to use these methods in the
specific context of medical devices, an evaluation is needed to verify their applicability for assessing
skin sensitization of medical devices. Given the number of candidate test methods and the time that
is required to assess them, it is important to ensure that the same science-based evaluation process
and criteria are consistently applied to any new candidate test method. The purpose of this document
is to provide a framework for the conduct of prevalidation and interlaboratory studies to assess the
applicability of candidate test methods for assessing one or more key events related to OECD’s adverse
[2]
outcome pathway (AOP) for skin sensitization when evaluating medical devices .
v
© ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 11796:2023(E)
Biological evaluation of medical devices — Requirements
for interlaboratory studies to demonstrate the
applicability of validated in vitro methods to assess the
skin sensitization of medical devices
1 Scope
This document specifies the framework and the methodology to evaluate and demonstrate the
applicability of a validated non-animal method from an OECD test guideline to assess the skin sensitizing
potential of a medical device or a medical device material. This document addresses:
— the database of reference chemical skin sensitizers and non-skin sensitizers;
— reference materials;
— feasibility testing of candidate test methods, including any method optimization for use with
extracts of medical devices;
— prevalidation of candidate test methods;
— the interlaboratory study:
— sample preparation and coding;
— spiking of the extracts from the negative control medical device material;
— data collection;
— statistical analysis to assess reliability and reproducibility.
The use of the approaches described in this document to assess the applicability of a candidate test
method does not imply that the candidate test method can be used as a stand-alone test for evaluating
the skin sensitization potential of medical devices. For certain candidate test methods, integrated
[1]
approaches and/or defined approaches are needed. The evaluation of skin sensitization potential of a
medical device is described in ISO 10993-10.
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 10993-12, Biological evaluation of medical devices — Part 12: Sample preparation and reference
materials
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
1
© ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/TS 11796:2023(E)
3.1
allergen
sensitizer
substance or material that is capable of inducing a specific hypersensitivity reaction upon repeated
contact with that substance or material
3.2
candidate test method
test method for in vitro skin sensitization testing of medical devices that is under evaluation
3.3
interlaboratory study
ILS
organization, performance and evaluation of measurements or tests on the same or similar items by
two or more laboratories according to predetermined conditions
3.4
interlaboratory reproducibility
between-laboratory reproducibility
measure of the extent to which different qualified laboratories, using the same protocol and testing the
same substances, can produce qualitatively and quantitatively similar results
Note 1 to entry: Interlaboratory reproducibility is determined during the prevalidation and validation processes,
[29]
and indicates the extent to which a test can be successfully transferred between laboratories.
3.5
intralaboratory reproducibility
within-laboratory reproducibility
determination of the extent that qualified people within the same laboratory can successfully replicate
results using a specific protocol at different times
3.6
prevalidation
PRE
initial phase of a validation (3.10) small-scale study intended to obtain preliminary information on the
relevance and reliability of a candidate test method (3.2)
3.7
test article
material (e.g. a final finished device or a reference material) that is to be used to generate a test sample
(3.8) (e.g. using extraction)
3.8
test sample
sample (e.g. a test article extract or spiked extract vehicle) that in its present form can be evaluated by
a candidate test method
3.9
test system
system (e.g. in vivo animal model, in vitro cellular model and in-silico computational models) that is
used for hazard identification as part of a test method
3.10
validation
confirmation, through the provision of objective evidence, that the requirements for a specific intended
use or application have been fulfilled
[SOURCE: ISO 9000:2015, 3.8.13, modified — Notes 1, 2 and 3 to entry have been deleted.]
2
© ISO 2023 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TS 11796:2023(E)
4 Consideration on the process for demonstration of the applicability domain
The process for evaluating the applicability of a candidate test method for skin sensitization testing of
medical devices shall include feasibility, prevalidation and interlaboratory studies (see Figure 1).
The required sample size was determined according to Reference [80]. The basis for the determination
was that the candidate test methods for the application to medical device extracts or medical device
material extracts, predict the spiked extracts (non-skin sensitizer versus skin sensitizer) as good as
the original OECD test method with the neat chemicals used for spiking the extracts. To demonstrate
concordance of results, it was assumed that at least 90 % of the test samples were predicted
concordantly in the candidate test method as compared to the original OECD test method. It was also
assumed that the concordance was not below 70 %. Considering a one-sided proportion of 0,05 and a
power of 0,8, a sample size of 28 was calculated. The sample size was increased to 29 to account for
potential drop-out of chemicals, e.g. due to commercial unavailability.
Prior to conducting a prevalidation study, a feasibility study may be needed to determine if any
modification of the OECD TG protocols (e.g. dilution, solvents, incubation times, volume of test sample,
stimulation index value) is necessary for the evaluation of medical devices.
Protocols for feasibility studies are not described in this document as the design of these studies should
be specific to the OECD TG method.
If the candidate test method protocols planned for the prevalidation and interlaboratory studies
deviate from the OECD TG protocol, the number and nature of the modifications as well as the data and
documentation available (e.g. from a feasibility study) to support the modifications shall be provided.
A scientific rationale for the impact of these changes on the acceptance of the method for assessing the
skin sensitizing potential of sample tests should be provided to justify that the method used remains
equivalent to the original OECD method.
The same candidate test method and protocols shall be used for both the prevalidation study and the
interlaboratory study.
As the non-animal methods considered are already validated with single chemicals (but not with
mixtures such as medical devices extracts) and integrated in OECD test guidelines (e.g. see Reference
[91] and Reference [1] on defined approaches for skin sensitization) with historical data of chemicals
assessment, the prevalidation step shall be conducted to:
a) prepare the standard operating procedures (SOPs), so that they can be readily used by other
laboratories;
b) generate preliminary data on the reliability and relevance of the candidate test method for
assessing skin sensitization of medical devices.
During the prevalidation and interlaboratory phases, evaluation of the performance of non-animal
methods shall be performed with positive and negative control test samples (in accordance with
Clause 5) that are representative of medical devices extracts. The concordance of results (compared to
the original OECD test method) and reproducibility shall be calculated and compared to the targeted
performance values in Clause 7 and Clause 8.
If the prevalidation study does not achieve the performance criteria in accordance with Clause 7, then
additional feasibility testing can be needed to optimize the assay protocol for increased concordance
and/or intralaboratory reproducibility prior to conducting a repeat prevalidation study. If the
prevalidation study meets the performance criteria in accordance with Clause 7, then an interlaboratory
study can be considered.
3
© ISO 2023 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/TS 11796:2023(E)
Figure 1 — General process for the evaluation of candidate test methods
5 Positive and negative control test samples
5.1 General
Due to the lack of existing positive reference test articles, samples for prevalidation and interlaboratory
studies are comprised of negative reference material extracts spiked with a known concentration
of a chemical skin sensitizer. By spiking an extract of an existing medical device material, the
4
© ISO 2023 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/TS 11796:2023(E)
final composition of test samples evaluated by in vitro test methods can better mimic the chemical
complexity of a real extract containing a low concentration of one or more chemical skin sensitizers.
For this purpose, chemical skin sensitizers and non-skin sensitizers that can be identified in extracts
of certain medical device materials have been selected. Annex A contains a database of reference
chemicals with animal, and human data when available, that will be used in the prevalidation and
interlaboratory studies.
5.2 Database of reference chemicals
A list of reference chemicals was developed including chemicals:
— representative of raw materials and/or leachables found in medical devices;
— representative of a balanced range of skin sensitizer potency (weak, moderate, strong and extreme);
— supported by robust reference data on potency and no-observed-adverse-effect-levels (NOAELs)
from human and animal sources, including human repeat insult patch test (HRIPT), human
maximization test (HMT), local lymph node assay (LLNA), closed-patch (Buehler) test and guinea
pig maximization test (GPMT).
Additional criteria considered for selection of chemicals are:
— to be representative of the different mechanisms by which the compounds exert a skin sensitization
effect;
— a range of physicochemical properties considered relevant to skin sensitization in Reference [1];
— commercially available compounds.
According the sample size considerations, a total of 29 chemicals are required. For each candidate test
method evaluated, the results obtained for the original OECD test methods with neat chemicals will be
collected or, when not available, generated experimentally.
NOTE The selection of chemicals already detected in medical devices or medical device materials was
based on a review of References [3][4][5][6] and [7]. Particular attention was paid to the quality of the historical
toxicological data for these chemicals. The estimated concentrations required to generate a threefold stimulation
[8]
of proliferation in draining lymph node (EC3 values) are derived from curated databases such as SkinSenseDB,
[9]
the Cosmetics Europe database, supplementary data from Reference [10], the integrated chemical environment
[11]
(ICE) from the national toxicology program (NTP), the National Toxicology Program Interagency Centre
[12]
for the Evaluation of Alternative Toxicological Methods (NICEATM) LLNA Database and the OECD curated
[13][14][15]
database for OECD Guideline 497 .
1)
®
All chemicals are presented in Table 1 with name, CAS Registry Number , medical devices application
examples and the spiking concentration to be used for prevalidation and interlaboratory studies.
Additional information on their physicochemical and skin sensitizing properties in humans and
animals is presented in Annex A (e.g. GPMT, LLNA EC3, human potency, reference publications and
complementary data).
®
1) CAS Registry Number is a trademark of the American Chemical Society (ACS). This information is given for
the convenience of users of this document and does not constitute an endorsement by ISO of the product named.
Equivalent products may be used if they can be shown to lead to the same results.
5
© ISO 2023 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/TS 11796:2023(E)
Table 1 — Database of reference chemicals for PRE and ILS
S/NS Set Name CAS Application in the medical device industry Spiking
concentration
w/v
%
Disinfectant and crosslinker for animal derived
S PRE Glutaraldehyde 111-30-8 0,08
tissue product
S PRE 1,4-Phenylenediamine 106-50-3 — 0,11
S PRE Phthalic anhydride 85-44-9 — 0,16
S PRE Cobalt chloride 7646-79-9 Orthopaedic implants, stents, pacemakers 0,4
S PRE Phenylacetaldehyde 122-78-1 — 3
S ILS Hydratropic aldehyde 93-53-8 — 6,3
Alpha-
S PRE 101-86-0 Ink, lubricants, etc. 10,8
hexylcinnamaldehyde
S PRE Linolenic acid 463-40-1 Lubricants 9,9
Acrylates, methacrylates and monomers
S PRE Ethyl acrylate 140-88-5 Found in adhesives, wearable devices, wound 10
dressings
TPO (diphenyl(2,4,6- Photo-initiator for additive manufacturing in
S PRE trimethylbenzoyl) 75980-60-8 many light-cured acrylic polymers) such as 27
phosphine oxide) composite materials, dental fillers, etc.
2,4,7,9-Tetramethyl-5-
S PRE 126-86-3 Plastic and rubber products 34,3
decyn-4,7-diol
S PRE Isopropyl myristate 110-27-0 Plasticizer, lubricant 44
S PRE Tridecane 629-50-5 Solvent, rubber industry 48,4
S PRE Methyl methacrylate 80-62-6 Bone cement, dental materials, hearing aids 75
Solvent, plasticizer, extractable associated
NS PRE Diethyl phthalate 84-66-2 1
with polyethylene and PET
Rubber accelerators
NS PRE 1,3-diphenylguanidine 102-06-7 1
Found in gloves
NS PRE Zinc oxide 1314-13-2 Anti-bacterial and anti-biofilm activity 1
2,4-Dinitrochlorobenzen
S ILS 97-00-7 — 0,06
(DNCB)
Formaldehyde Sterilization-low temperature steam and for-
S ILS 50-00-0 0,3
(act. 37 %) maldehyde (LTSF)
Plastic materials, valves, tubes lining, stoppers,
sealants, coatings, inks, glues
S ILS Isobornyl acrylate (IBOA) 5888-33-5 Found in adhesives, wearable devices such 1
as glucose monitoring sensors, insulin patch
pumps and some wound dressings
2-Mercaptobenzothiazole Rubber accelerators
S ILS 149-30-4 1,35
(MBT) Gloves
Acrylates, methacrylates and monomers
S ILS 2-hydroxyethyl acrylate 818-61-1 Wound dressings, EKG electrodes, contact 1,4
lenses
Nickel(II) sulfate hexahydrate 10101-97-0 Nickel alloys and stainless steels in implanta-
S ILS 4,8
(NiSO ) 7786-81-4 ble medical devices
4
Adhesives
S ILS Abietic acid 514-10-3 15
Wound dressing
Key
S skin sensitizer
NS non-skin sensitizer
w weight
v volume
The database of reference chemicals contains 29 chemicals, 7 non-skin sensitizers and 22 skin sensitizers. The selected chemicals are distributed in two
sets. The first set of 16 chemicals (13 skin sensitizers and 3 non-skin sensitizers) which shall be used for the prevalidation phase, are labelled “PRE” in
Table 1 and are included in Clause A.1. The second set of 13 chemicals (9 sensitizers and 4 non sensitizers) which shall be used for the interlaboratory study
phase, are labelled “ILS” in Table 1 and included in Clause A.2. The size of this set, 13 chemicals, represents half the number of chemicals originally used
for the validation of OECD test methods. It was considered appropriate from a statistical point of view because minor deviation of the protocols during the
feasibility study are unlikely to affect the transferability and interlaboratory reproducibility.
6
© ISO 2023 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/TS 11796:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
S/NS Set Name CAS Application in the medical device industry Spiking
concentration
w/v
%
Intermediate used in the manufacture of plasti-
S ILS α-Methylstyrene 98-83-9 46
cizers, resins and polymers
NS ILS Chlorobenzene 108-90-7 Intermediate in rubber, solvent in adhesives 1
NS ILS Octanoic acid 124-07-2 Antibacterial agent 1
NS ILS Glycerol 56-81-5 Lubricant 1
Monomer of polymer polylactic acid (PLA). PLA
is commonly used in biodegradable polymers
NS ILS Lactic acid 50-21-5 for drug delivery systems, tissue engineering, 1
temporary and long-term implantable devices,
etc.
Key
S skin sensitizer
NS non-skin sensitizer
w weight
v volume
The database of reference chemicals contains 29 chemicals, 7 non-skin sensitizers and 22 skin sensitizers. The selected chemicals are distributed in two
sets. The first set of 16 chemicals (13 skin sensitizers and 3 non-skin sensitizers) which shall be used for the prevalidation phase, are labelled “PRE” in
Table 1 and are included in Clause A.1. The second set of 13 chemicals (9 sensitizers and 4 non sensitizers) which shall be used for the interlaboratory study
phase, are labelled “ILS” in Table 1 and included in Clause A.2. The size of this set, 13 chemicals, represents half the number of chemicals originally used
for the validation of OECD test methods. It was considered appropriate from a statistical point of view because minor deviation of the protocols during the
feasibility study are unlikely to affect the transferability and interlaboratory reproducibility.
The selected chemicals are representative of chemicals previously found in leaching studies of medical
devices extracts (see Annex A). The skin sensitizers cover the different potency categories according
[16]
to the European Centre for Ecotoxicology and Toxicology of Chemicals (ECET
...
ISO/DTS 11796:2022(X2023(E)
ISO/TC 194/WG 8
Date: YYYY-MM-DD
Secretariat: DIN
Biological evaluation of medical devices —
Requirements for interlaboratory studies to demonstrate the
applicability of validated in vitro methods to assess the skin sensitization of medical
devices
DTS stage
Warning for WDs and CDs
This document is not an ISO International Standard. It is distributed for review and comment. It is subject to change
without notice and may not be referred to as an International Standard.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which
they are aware and to provide supporting documentation.
© ISO 2021 – All rights reserved
---------------------- Page: 1 ----------------------
© ISO 20XX
First edition
Date: 2023-01-13
---------------------- Page: 2 ----------------------
ISO/DTS 11796:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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’sISO's member body in
the country of the requester.
ISO Copyright Office
CP 401 • CH. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Email: copyright@iso.org copyright@iso.org
Website: www.iso.orgwww.iso.org
Published in Switzerland.
iv © ISO 2023 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/DTS 11796:2023(E)
Contents
Foreword . 6
Introduction . 7
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Consideration on the process for demonstration of the applicability domain . 3
5 Positive and Negative Control Test Samples . 7
5.1 Database of reference chemicals . 7
5.2 Reference materials . 12
5.2.1 Negative control medical device material . 12
5.2.2 Positive reference material . 12
6 Preparation of the test samples . 13
6.1 Preparation of the extracts . 13
6.2 Spiking of the extracts. 13
7 Prevalidation of candidate test methods . 14
8 Interlaboratory study . 14
8.1 Study organization . 15
8.1.1 General . 15
8.1.2 Management team . 15
8.1.3 Lead laboratory . 15
8.1.4 Sample management . 15
8.1.5 Independent biostatistician . 15
8.2 Sample preparation . 15
8.3 Performance review . 16
9 Statistical analysis . 16
10 Test report . 16
Annex A (informative) Reference chemicals . 18
Bibliography . 34
© ISO 2023 – All rights reserved v
---------------------- Page: 4 ----------------------
ISO/DTS 11796:2023(E)
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 194, Biological and clinical evaluation of
medical devices, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 206, Biological and clinical evaluation of medical devices, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 10993 series can be found on the ISO website.
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.
vi © ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
ISO/DTS 11796:2023(E)
Introduction
International Standards can be used to demonstrate the safety and compliance of medical devices. ISO
10993-10 specifies the procedure for the assessment of medical devices and their constituent materials
with regard to their potential to induce skin sensitization (Type IV hypersensitivity reaction). The
methods included in ISO 10993-10 are based on animal or human testing, with an informative annex on
in vitro and in chemico tests for skin sensitization that have been validated for neat chemicals. The effort
to reduce or replace the use of animals in toxicity testing has led to the development of many new non-
animal methods. The OECD test guidelines in the 442 seriesReferences [56] and [57] include alternatives
to animal testing methods for skin sensitization that have been previously validated to confirm their
equivalence/superiority to the current in vivo methods. However, currently, none of the OECD test
guideline methods are considered sufficient stand-alone replacements for in vivo tests that assess the
[1]
skin sensitization potential of chemicals. .
Current OECD test guideline methods are validated with neat chemicals and not with more complex
mixtures such as medical devices or medical devices extracts. In order to use these methods in the specific
context of medical devices, an evaluation is needed to verify their applicability for assessing skin
sensitization of medical devices. Given the number of candidate test methods and the time that is required
to assess them, it is important to ensure that the same science-based evaluation process and criteria are
consistently applied to any new candidate test method. The purpose of this document is to provide a
framework for the conduct of prevalidation and interlaboratory studies to assess the applicability of
candidate test methods for assessing one or more key events related to OECD’s adverse outcome pathway
[2]
(AOP) for skin sensitization when evaluating medical devices. .
© ISO 2023 – All rights reserved vii
---------------------- Page: 6 ----------------------
TECHNICAL SPECIFICATION ISO/DTS 11796:2023(E)
NOTE For a candidate test method evaluated per this document to be
considered for inclusion in ISO 10993-10, the test report can be
submitted to ISO/TC 194/WG 8.Biological evaluation of medical
devices — Requirements for interlaboratory studies to demonstrate
the applicability of validated in vitro methods to assess the skin
sensitization of medical devices
1 Scope
This document specifies the framework and the methodology to evaluate and demonstrate the
applicability of a validated non-animal method from an OECD test guideline to assess the skin sensitizing
potential of a medical device or a medical device material. This document addresses:
— database of reference chemical skin sensitizers and non -sensitizers;
— reference materials;
— feasibility testing of candidate test methods, including any method optimization for use with extracts
of medical devices;
— prevalidation of candidate test methods;
— interlaboratory study:
— sample preparation and coding;
— spiking of the extracts of negative control medical device material;
— collection of the data;
— statistical analysis to assess reliability and reproducibility.
The use of the approaches described in this document to assess the applicability of a candidate test
method does not imply that the candidate test method can be used as stand-alone test for the evaluation
of skin sensitization potential of medical devices. For certain candidate test methods, integrated
[1]
approaches and/or defined approaches may beare needed. The evaluation of skin sensitization
potential of a medical device is described in ISO 10993:-10.
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 10993-12:2021, Biological evaluation of medical devices — Part 12: Sample preparation and reference
materials
© ISO 2023 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO/DTS 11796:2023(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminologicalterminology databases for use in standardization at the following
addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
allergen
sensitizer
substance or material that is capable of inducing a specific hypersensitivity reaction upon repeated
contact with that substance or material
3.2
allergic contact dermatitis
clinical diagnosis based on an observed immunologically-mediated cutaneous reaction to a substance
3.3
candidate test method
test method for in vitro sensitization testing of medical devices that is under evaluation
3.43
interlaboratory study
round robin study
ILS
organization, performance and evaluation of measurements or tests on the same or similar items by two
or more laboratories in accordance withaccording to predetermined conditions
3.4
interlaboratory reproducibility
between-laboratory reproducibility
measure of the extent to which different qualified laboratories, using the same protocol and testing the
same substances, can produce qualitatively and quantitatively similar results
Note 1 to entry: Interlaboratory reproducibility is determined during the prevalidation and validation processes,
[29]
and indicates the extent to which a test can be successfully transferred between laboratories.
3.5
intralaboratory studyreproducibility
organization, performance and evaluationwithin-laboratory reproducibility
determination of measurements or tests on the same or similar itemsextent that qualified people within
the same laboratory in accordance with predetermined conditionscan successfully replicate results using
a specific protocol at different times
3.6
prevalidation
PRE
initial phase of a validation study;(3.10) small-scale study intended to obtain preliminary information on
the relevance and reliability of a candidate test method (3.2)
3.7
2 © ISO 2023 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/DTS 11796:2023(E)
test article
material (e.g.,. a final finished device or a reference material) that is to be used to generate a test sample
(3.8) (e.g.,. using extraction)
3.8
test sample
sample (e.g.,. a test article extract or spiked extract vehicle) that in its present form can be evaluated by a
candidate test method
3.9
test system
system (e.g.,. in vivo animal model, in vitro cellular model, and in-silico computational models) that is
used for hazard identification as part of a test method
3.10
validation
confirmation, through the provision of objective evidence, that the requirements for a specific intended
use or application have been fulfilled
[SOURCE: ISO 9000:2015, 3.8.13, modified – Note— Notes 1, 2 and 3 to entry hashave been deleted.]
4 Consideration on the process for demonstration of the applicability domain
The process for evaluating the applicability of a candidate test method for sensitization testing of medical
devices shall include feasibility, prevalidation, and interlaboratory studies (see Figure 1).
Prior to conducting a prevalidation study, a feasibility study may be needed to determine if any
modification of the OECD TG protocols (e.g. dilution, solvents, incubation times, volume of test sample,
stimulation index value) is necessary for the evaluation of medical devices.
Protocols for feasibility studies are not described in this document as the design of these studies should
be specific to the OECD TG method.
If the candidate test method protocols planned for the prevalidation and interlaboratory studies deviate
from the OECD TG protocol, the number and nature of the modifications as well as the data and
documentation available (e.g. from a feasibility study) to support the modifications shall be provided. A
scientific rationale for the impact of these changes on the acceptance of the method for assessing the
sensitizing potential of sample tests should be provided to justify that the method used remains
equivalent to the original OECD method.
The same candidate test method and protocols shall be used for both the prevalidation study and the
interlaboratory study.
As the non-animal methods considered are already validated with single chemicals (but not with mixtures
such as medical devices extracts) and integrated in OECD test guidelines (e.g., OECD 442 series. see
Reference [91] and OECD guideline 497Reference [1] on defined approaches for sensitization) with
historical data of chemicals assessment, the prevalidation step shall be conducted to:
a) prepare the standard operating procedures (SOPs), so that they can be readily used by other
laboratories;
b) generate preliminary data on the reliability and relevance of the candidate test method for assessing
skin sensitization of medical devices.
© ISO 2023 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO/DTS 11796:2023(E)
During the prevalidation and interlaboratory phases, evaluation of the performance of non-animal
methods shall be performed with positive and negative control test samples (in accordance with Clause 5)
that are representative of medical devices extracts. The accuracy, sensitivity, specificity and
reproducibility shall be calculated and compared to the targeted performance values in Clause 7 and
Clause 8.
If the prevalidation study does not achieve the performance criteria in accordance with Clause 7, then
additional feasibility testing may be needed to optimize the assay protocol for increased accuracy,
specificity, and/or intralaboratory reproducibility prior to conducting a repeat prevalidation study. If the
prevalidation study meets the performance criteria in accordance with Clause 7, then an interlaboratory
study can be considered.
4 © ISO 2023 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/DTS 11796:2023(E)
© ISO 2023 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO/DTS 11796:2023(E)
Figure 1 — General process for the evaluation of candidate test methods
6 © ISO 2023 – All rights reserved
---------------------- Page: 12 ----------------------
ISO/DTS 11796:2023(E)
5 Positive and negative control test samples
5.1 General
Due to the lack of existing positive reference materialstest articles, samples for prevalidation and
interlaboratory studies are comprised ofcomprise negative reference material extracts spiked with a
known concentration of a chemical skin sensitizer. By spiking an extract of an existing medical device
material, the final composition of test samples tested by candidate in vitro test methods can better mimic
the chemical complexity of a real extract containing a low concentration of one or more chemical skin
sensitizers.
For this purpose, chemical skin sensitizers and non -sensitizers that can be identified in extracts of certain
medical device materials have been selected. Annex A includes animal, and human data when available,
to serve as a reference database for prevalidation and interlaboratory studies.
5.15.2 Database of reference chemicals
A list of reference chemicals was developed including chemicals:
— representative of raw materials and/or leachables found in medical devices;
— representative of a balanced range of skin sensitizer potency (weak, moderate, and strong);
— supported by robust reference data on potency and no-observed-adverse-effect-levels (NOAELs)
from human and animal sources, including human repeat insult patch test (HRIPT), human
maximization test (HMT), local lymph node assay (LLNA), closed-patch (Buehler) test, and guinea-
pig maximization test (GPMT).
Additional criteria considered for selection of chemicals are:
— to be representative of the different mechanisms by which the compounds exert a sensitization effect;
— a range of physicochemical properties considered relevant to skin sensitization in the supporting
document to the OECD guideline 497;Reference [1];
— commercially available compounds.
NOTE The selection of chemicals already detected in medical devices or medical device materials was based on a
[3][4][5][6][7]
review of the scientific literature. Particular attention was paid to the quality of the historical toxicological
data for these chemicals. The estimated concentrations required to generate a threefold stimulation of proliferation
[8]
in draining lymph node (EC3 values) are derived from curated databases such as SkinSenseDB,, the Cosmetics
[9]
Europe database,, supplementary data from Urbish et al ,Reference [10], the integrated chemical environment
[11]
(ICE) from the national toxicology program (NTP),), the National Toxicology Program Interagency Centre for the
[12]
Evaluation of Alternative Toxicological Methods (NICEATM) LLNA Database and the OECD curated database for
[13][14][15]
OECD guideline 497. .
1
®
All chemicals are presented in Table 1 with name, CAS numberRegistry Number , medical devices
application examples and the spiking concentration to be used for prevalidation and interlaboratory
studies. Additional information on their physicochemical and skin sensitizing properties in
humanhumans and animalanimals is presented in Annex A (e.g. GPMT, LLNA EC3, human potency,
reference publications and complementary data).
1
®
CAS Registry Number is a trademark of the American Chemical Society (ACS). This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent
products may be used if they can be shown to lead to the same results.
© ISO 2023 – All rights reserved 7
---------------------- Page: 13 ----------------------
ISO/DTS 11796:2023(E)
Table 1 — Database of reference chemicals for prevalidation (PRE) and interlaboratory studies
(ILS)
8 © ISO 2023 – All rights reserved
---------------------- Page: 14 ----------------------
ISO/DTS 11796:2023(E)
S/NS Set Name CAS Application in the medical Spiking
device (MD) industry concentration
weight per
volume (w/v)
%
S PRE Glutaraldehyde 111–30–8 Disinfectant and crosslinker for 0,08
animal derived tissue product
S PRE 1,4-Phenylenediamine 106–50–3 0,11
S PRE Phthalic anhydride 85–44–9 0,16
S PRE Cobalt chloride 7646–79–9 Orthopaedic implants, stents, 0,4
pacemakers
S PRE Phenylacetaldehyde 122–78–1 3
S PRE Hydratropic aldehyde 93–53–8 6,3
S PRE Alpha- 101-86-0 Ink, lubricants, etc. 10,8
hexylcinnamaldehyde
S PRE Linolenic acid 463–40–1 Lubricants 9,9
S PRE Ethyl acrylate 140–88–5 Acrylates, methacrylates and 10
monomers
Found in adhesives, wearable
devices, wound dressings
S PRE TPO (Diphenyl(2,4,6- 75980–60–8 Photo-initiator for additive 27
trimethylbenzoyl)phos manufacturing in many light-
phine oxide) cured acrylic polymers) such as
composite materials, dental
fillers, etc.
S PRE 2,4,7,9-Tetramethyl-5- 126–86–3 Plastic and rubber products 34,3
decyn-4,7-diol
S PRE Isopropyl myristate 110–27–0 Plasticizer, lubricant 44
S PRE Tridecane 629–50–5 solvent, rubber industry 48,4
S PRE Methyl methacrylate 80–62–6 Bone cement, dental materials, 75
hearing aids
NS PRE Diethyl phtalate 84–66–2 Solvent, plasticizer, extractable 1
associated with polyethylene and
PET
NS PRE 1,3-diphenylguanidine 102–06–7 Rubber accelerators 1
Found in gloves
NS PRE Zinc oxide 1314–13–2 Anti-bacterial and anti-biofilm 1
activity
S ILS 2,4- 97–00–7 0,06
Dinitrochlorobenzen
DNCB
S ILS Formaldehyde (act. 50–00–0 Sterilization-low temperature 0,3
37 %) steam and formaldehyde (LTSF)
© ISO 2023 – All rights reserved 9
---------------------- Page: 15 ----------------------
ISO/DTS 11796:2023(E)
S ILS Isobornyl acrylate 5888–33–5 Plastic materials, valves, tubes 1
(IBOA) lining, stoppers, sealants,
coatings, inks, glues
Found in adhesives, wearable
devices such as glucose
monitoring sensors, insulin patch
pumps and some wound
dressings
S ILS 2- 149–30–4 Rubber accelerators 1,35
Mercaptobenzothiazol Gloves
e (MBT)
S ILS 2-hydroxyethyl 818–61–1 Acrylates, methacrylates and 1,4
acrylate monomers
Wound dressings, EKG electrodes,
Contact lenses
S ILS Nickel(II) sulfate 10101–97–0 Nickel alloys and stainless steels 4,8
hexahydrate (NiSO4) 7786–81–4 in implantable medical devices
S ILS Abietic acid 514–10–3 Adhesives 15
Wound dressing
S ILS α-Methylstyrene 98–83–9 Intermediate used in the 46
manufacture of plasticizers,
resins and polymers
NS ILS Chlorobenzene 108–90–7 Intermediate in rubber, solvent in 1
adhesives
NS ILS Octanoic acid 124–07–2 Lubricant 1
NS ILS Glycerol 56–81–5 1
NS ILS Lactic Acid 50–21–5 Monomer of polymer polylactic 1
acid (PLA). PLA is commonly used
in biodegradable polymers for
drug delivery systems, tissue
engineering, temporary and long-
term implantable devices, etc.
Key
S sensitizer
NS non sensitizer
The database of reference chemicals contains 29 chemicals, 7 non sensitizers and 22 skin sensitizers. The selected chemicals
are distributed in two sets. The first set of 17 chemicals (14 sensitizers and 3 non sensitizers) which shall be used for the
prevalidation phase, are labelled “PRE” in Table 1 and included in Clause A.1. The second set of 12 chemicals (8 sensitizers
and 4 non sensitizers) which shall be used for the interlaboratory study phase, are labelled “ILS” in Table 1 and included in
Clause A.2. The size of this set, 12 chemicals, represents half the number of chemicals originally used for the validation of
OECD test methods. It was considered appropriate from a statistical point of view because minor deviation of the protocols
during the feasibility study are unlikely to affect the transferability and interlaboratory reproducibility.
The selected chemicals are representative of chemicals previously found in leaching studies of medical
devices extracts (see Annex A). The skin sensitizers cover the different potency categories according to
[16]
the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) classification as
represented in Figure 2: 8 weak, 9 moderate, 3 strong and 2 extreme skin sensitizers.
10 © ISO 2023 – All rights reserved
---------------------- Page: 16 ----------------------
ISO/DTS 11796:2023(E)
Figure 2 — Distribution of EC3 values of the reference chemical skin sensitizers
The physicochemical properties considered relevant to skin sensitization in the supporting document to
the OECD guideline 497Reference [1] are presented in Table 2 for the 29 chemicals selected compared to
[13]
the 167 chemicals of the OECD database. .
Table 2 — Summary of the physicochemical property ranges that describe the chemical space of
the chemicals tested in this document and in the OECD guideline 497Reference [1]
© ISO 2023 – All rights reserved 11
---------------------- Page: 17 ----------------------
ISO/DTS 11796:2023(E)
[1]
OECD guideline 497 This document
ISO/TS 11796
Property min. to max. min. to max.
MW (g/mol) [30,0 to 512,6] [30,0 to 348,4]
LogP [−3,9 to 9,4] [−1,8 to 7,5]
LogWS (mol/l) [−7,6 to 1,2] [−7,6 to 1,2]
MP (°C) [−122,5 to 252,7] [−105 to 411]
BP (°C) [−19,1 to 445,3] [−19,1 to 1 000]
LogVP [−18,7 to 11,6] [−8,5 to 2,916]
Key
MW molecular weight
BP boiling point
MP melting point
LogVP vapour pressure
LogP octanol-water partition coefficient
LogWS water solubility
5.25.3 Reference materials
5.3.1 General
In order to reproduce the real-life conditions of a medical device evaluation, a negative control medical
device material shall be extracted under the usual extraction conditions used in an in vivo test. The
negative control medical device material shall be a material commonly used in medical devices and
known to release a complex mixture of non-sensitizing chemicals representative of a medical device
extract. The polar and non-polar extracts of this negative control medical device material shall then be
spiked with the skin sensitizing or non-sensitizing chemicals to perform the evaluation.
5.2.15.3.2 Negative control medical device material
The negative control medical device material shall be a silicone available commercially and known to
release numerous compounds without eliciting a positive sensitization response. MED-2000 silicone
2
supplied by Nusil Technology shouldcan be used as negative control medical device material. Use of any
alternative negative control medical device material shall be described and justified. After extraction
according to ISO 10993-12, the extracts shall be used as a negative control and for preparing the test
samples by spiking these extracts with skin sensitizing and non-sensitizing chemicals.
5.2.25.3.3 Positive reference material
If a positive certified refere
...
FINAL
TECHNICAL ISO/DTS
DRAFT
SPECIFICATION 11796
ISO/TC 194
Biological evaluation of medical
Secretariat: DIN
devices — Requirements for
Voting begins on:
2023-01-19 interlaboratory studies to
demonstrate the applicability of
Voting terminates on:
2023-03-16
validated in vitro methods to assess
the skin sensitization of medical
devices
Évaluation biologique des dispositifs médicaux — Guide pour les
études interlaboratoires visant à démontrer l'applicabilité des
méthodes in-vitro validées pour évaluer la sensibilisation cutanée des
dispositifs médicaux
IMPORTANT — Please use this updated version dated
2023-01-13, and discard any previous version of this DTS. Some
changes were added at Committee's request.
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/DTS 11796:2023(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 1 ----------------------
ISO/DTS 11796:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO 2023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DTS 11796:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Consideration on the process for demonstration of the applicability domain .3
5 Positive and negative control test samples . 4
5.1 General . 4
5.2 Database of reference chemicals . 5
5.3 Reference materials . 8
5.3.1 General . 8
5.3.2 Negative control medical device material . 9
5.3.3 Positive reference material . 9
6 Preparation of the test samples .9
6.1 General . 9
6.2 Preparation of the extracts . 9
6.3 Spiking of the extracts . 10
7 Prevalidation of candidate test methods .10
8 Interlaboratory study .11
8.1 General . 11
8.2 Study organization . 11
8.2.1 General . 11
8.2.2 Management team . 11
8.2.3 Lead laboratory . 11
8.2.4 Sample management . 11
8.2.5 Independent biostatistician . 11
8.3 Sample preparation . 11
8.4 Performance review .12
9 Statistical analysis .12
10 Test report .12
Annex A (informative) Reference chemicals .14
Bibliography .28
iii
© ISO 2023 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/DTS 11796:2023(E)
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 194, Biological and clinical evaluation of
medical devices.
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.
iv
© ISO 2023 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/DTS 11796:2023(E)
Introduction
International Standards can be used to demonstrate the safety and compliance of medical devices.
ISO 10993-10 specifies the procedure for the assessment of medical devices and their constituent
materials with regard to their potential to induce skin sensitization (Type IV hypersensitivity reaction).
The methods included in ISO 10993-10 are based on animal or human testing, with an annex on in vitro
and in chemico tests for skin sensitization that have been validated for neat chemicals. The effort to
reduce or replace the use of animals in toxicity testing has led to the development of many new non-
animal methods. The test guidelines in References [56] and [57] include alternatives to animal testing
methods for skin sensitization that have been previously validated to confirm their equivalence/
superiority to the current in vivo methods. However, currently, none of the OECD test guideline methods
are considered sufficient stand-alone replacements for in vivo tests that assess the skin sensitization
[1]
potential of chemicals .
Current OECD test guideline methods are validated with neat chemicals and not with more complex
mixtures such as medical devices or medical devices extracts. In order to use these methods in the
specific context of medical devices, an evaluation is needed to verify their applicability for assessing
skin sensitization of medical devices. Given the number of candidate test methods and the time that
is required to assess them, it is important to ensure that the same science-based evaluation process
and criteria are consistently applied to any new candidate test method. The purpose of this document
is to provide a framework for the conduct of prevalidation and interlaboratory studies to assess the
applicability of candidate test methods for assessing one or more key events related to OECD’s adverse
[2]
outcome pathway (AOP) for skin sensitization when evaluating medical devices .
v
© ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/DTS 11796:2023(E)
Biological evaluation of medical devices — Requirements
for interlaboratory studies to demonstrate the
applicability of validated in vitro methods to assess the
skin sensitization of medical devices
1 Scope
This document specifies the framework and the methodology to evaluate and demonstrate the
applicability of a validated non-animal method from an OECD test guideline to assess the skin sensitizing
potential of a medical device or a medical device material. This document addresses:
— database of reference chemical skin sensitizers and non sensitizers;
— reference materials;
— feasibility testing of candidate test methods, including any method optimization for use with
extracts of medical devices;
— prevalidation of candidate test methods;
— interlaboratory study:
— sample preparation and coding;
— spiking of the extracts of negative control medical device material;
— collection of the data;
— statistical analysis to assess reliability and reproducibility.
The use of the approaches described in this document to assess the applicability of a candidate test
method does not imply that the candidate test method can be used as stand-alone test for the evaluation
of skin sensitization potential of medical devices. For certain candidate test methods, integrated
[1]
approaches and/or defined approaches are needed. The evaluation of skin sensitization potential of a
medical device is described in ISO 10993-10.
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 10993-12, Biological evaluation of medical devices — Part 12: Sample preparation and reference
materials
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
1
© ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/DTS 11796:2023(E)
3.1
allergen
sensitizer
substance or material that is capable of inducing a specific hypersensitivity reaction upon repeated
contact with that substance or material
3.2
candidate test method
test method for in vitro sensitization testing of medical devices that is under evaluation
3.3
interlaboratory study
ILS
organization, performance and evaluation of measurements or tests on the same or similar items by
two or more laboratories according to predetermined conditions
3.4
interlaboratory reproducibility
between-laboratory reproducibility
measure of the extent to which different qualified laboratories, using the same protocol and testing the
same substances, can produce qualitatively and quantitatively similar results
Note 1 to entry: Interlaboratory reproducibility is determined during the prevalidation and validation processes,
[29]
and indicates the extent to which a test can be successfully transferred between laboratories.
3.5
intralaboratory reproducibility
within-laboratory reproducibility
determination of the extent that qualified people within the same laboratory can successfully replicate
results using a specific protocol at different times
3.6
prevalidation
PRE
initial phase of a validation (3.10) small-scale study intended to obtain preliminary information on the
relevance and reliability of a candidate test method (3.2)
3.7
test article
material (e.g. a final finished device or a reference material) that is to be used to generate a test sample
(3.8) (e.g. using extraction)
3.8
test sample
sample (e.g. a test article extract or spiked extract vehicle) that in its present form can be evaluated by
a candidate test method
3.9
test system
system (e.g. in vivo animal model, in vitro cellular model and in-silico computational models) that is
used for hazard identification as part of a test method
3.10
validation
confirmation, through the provision of objective evidence, that the requirements for a specific intended
use or application have been fulfilled
[SOURCE: ISO 9000:2015, 3.8.13, modified — Notes 1, 2 and 3 to entry have been deleted.]
2
© ISO 2023 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/DTS 11796:2023(E)
4 Consideration on the process for demonstration of the applicability domain
The process for evaluating the applicability of a candidate test method for sensitization testing of
medical devices shall include feasibility, prevalidation and interlaboratory studies (see Figure 1).
Prior to conducting a prevalidation study, a feasibility study may be needed to determine if any
modification of the OECD TG protocols (e.g. dilution, solvents, incubation times, volume of test sample,
stimulation index value) is necessary for the evaluation of medical devices.
Protocols for feasibility studies are not described in this document as the design of these studies should
be specific to the OECD TG method.
If the candidate test method protocols planned for the prevalidation and interlaboratory studies
deviate from the OECD TG protocol, the number and nature of the modifications as well as the data and
documentation available (e.g. from a feasibility study) to support the modifications shall be provided.
A scientific rationale for the impact of these changes on the acceptance of the method for assessing
the sensitizing potential of sample tests should be provided to justify that the method used remains
equivalent to the original OECD method.
The same candidate test method and protocols shall be used for both the prevalidation study and the
interlaboratory study.
As the non-animal methods considered are already validated with single chemicals (but not with
mixtures such as medical devices extracts) and integrated in OECD test guidelines (e.g. see Reference
[91] and Reference [1] on defined approaches for sensitization) with historical data of chemicals
assessment, the prevalidation step shall be conducted to:
a) prepare the standard operating procedures (SOPs), so that they can be readily used by other
laboratories;
b) generate preliminary data on the reliability and relevance of the candidate test method for
assessing skin sensitization of medical devices.
During the prevalidation and interlaboratory phases, evaluation of the performance of non-animal
methods shall be performed with positive and negative control test samples (in accordance with
Clause 5) that are representative of medical devices extracts. The accuracy, sensitivity, specificity and
reproducibility shall be calculated and compared to the targeted performance values in Clause 7 and
Clause 8.
If the prevalidation study does not achieve the performance criteria in accordance with Clause 7, then
additional feasibility testing may be needed to optimize the assay protocol for increased accuracy,
specificity and/or intralaboratory reproducibility prior to conducting a repeat prevalidation study.
If the prevalidation study meets the performance criteria in accordance with Clause 7, then an
interlaboratory study can be considered.
3
© ISO 2023 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/DTS 11796:2023(E)
Figure 1 — General process for the evaluation of candidate test methods
5 Positive and negative control test samples
5.1 General
Due to the lack of existing positive reference test articles, samples for prevalidation and interlaboratory
studies comprise negative reference material extracts spiked with a known concentration of a chemical
skin sensitizer. By spiking an extract of an existing medical device material, the final composition of
4
© ISO 2023 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/DTS 11796:2023(E)
test samples tested by candidate in vitro test methods can better mimic the chemical complexity of a
real extract containing a low concentration of one or more chemical skin sensitizers.
For this purpose, chemical skin sensitizers and non sensitizers that can be identified in extracts of
certain medical device materials have been selected. Annex A includes animal, and human data when
available, to serve as a reference database for prevalidation and interlaboratory studies.
5.2 Database of reference chemicals
A list of reference chemicals was developed including chemicals:
— representative of raw materials and/or leachables found in medical devices;
— representative of a balanced range of skin sensitizer potency (weak, moderate and strong);
— supported by robust reference data on potency and no-observed-adverse-effect-levels (NOAELs)
from human and animal sources, including human repeat insult patch test (HRIPT), human
maximization test (HMT), local lymph node assay (LLNA), closed-patch (Buehler) test and guinea-
pig maximization test (GPMT).
Additional criteria considered for selection of chemicals are:
— to be representative of the different mechanisms by which the compounds exert a sensitization
effect;
— a range of physicochemical properties considered relevant to skin sensitization in Reference [1];
— commercially available compounds.
NOTE The selection of chemicals already detected in medical devices or medical device materials was based
[3][4][5][6][7]
on a review of the scientific literature. Particular attention was paid to the quality of the historical
toxicological data for these chemicals. The estimated concentrations required to generate a threefold stimulation
[8]
of proliferation in draining lymph node (EC3 values) are derived from curated databases such as SkinSenseDB,
[9]
the Cosmetics Europe database, supplementary data from Reference [10], the integrated chemical environment
[11]
(ICE) from the national toxicology program (NTP), the National Toxicology Program Interagency Centre
[12]
for the Evaluation of Alternative Toxicological Methods (NICEATM) LLNA Database and the OECD curated
[13][14][15]
database for OECD guideline 497 .
®1)
All chemicals are presented in Table 1 with name, CAS Registry Number , medical devices application
examples and the spiking concentration to be used for prevalidation and interlaboratory studies.
Additional information on their physicochemical and skin sensitizing properties in humans and
animals is presented in Annex A (e.g. GPMT, LLNA EC3, human potency, reference publications and
complementary data).
®
1) CAS Registry Number is a trademark of the American Chemical Society (ACS). This information is given for
the convenience of users of this document and does not constitute an endorsement by ISO of the product named.
Equivalent products may be used if they can be shown to lead to the same results.
5
© ISO 2023 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/DTS 11796:2023(E)
Table 1 — Database of reference chemicals for PRE and ILS
S/NS Set Name CAS Application in the medical de- Spiking concen-
vice (MD) industry tration weight
per volume (w/v)
%
S PRE Glutaraldehyde 111–30–8 Disinfectant and crosslinker for 0,08
animal derived tissue product
S PRE 1,4-Phenylenediamine 106–50–3 0,11
S PRE Phthalic anhydride 85–44–9 0,16
S PRE Cobalt chloride 7646–79–9 Orthopaedic implants, stents, 0,4
pacemakers
S PRE Phenylacetaldehyde 122–78–1 3
S PRE Hydratropic aldehyde 93–53–8 6,3
S PRE Alpha-hexylcinnamal- 101-86-0 Ink, lubricants, etc. 10,8
dehyde
S PRE Linolenic acid 463–40–1 Lubricants 9,9
S PRE Ethyl acrylate 140–88–5 Acrylates, methacrylates and 10
monomers
Found in adhesives, wearable de-
vices, wound dressings
S PRE TPO (Diphenyl(2,4,6-tri- 75980–60–8 Photo-initiator for additive man- 27
methylbenzoyl)phos- ufacturing in many light-cured
phine oxide) acrylic polymers) such as compos-
ite materials, dental fillers, etc.
S PRE 2,4,7,9-Tetrame- 126–86–3 Plastic and rubber products 34,3
thyl-5-decyn-4,7-diol
S PRE Isopropyl myristate 110–27–0 Plasticizer, lubricant 44
S PRE Tridecane 629–50–5 solvent, rubber industry 48,4
S PRE Methyl methacrylate 80–62–6 Bone cement, dental materials, 75
hearing aids
NS PRE Diethyl phtalate 84–66–2 Solvent, plasticizer, extractable 1
associated with polyethylene and
PET
NS PRE 1,3-diphenylguanidine 102–06–7 Rubber accelerators 1
Found in gloves
NS PRE Zinc oxide 1314–13–2 Anti-bacterial and anti-biofilm 1
activity
S ILS 2,4-Dinitrochloroben- 97–00–7 0,06
zen DNCB
S ILS Formaldehyde (act. 50–00–0 Sterilization-low temperature 0,3
37 %) steam and formaldehyde (LTSF)
Key
S sensitizer
NS non sensitizer
The database of reference chemicals contains 29 chemicals, 7 non sensitizers and 22 skin sensitizers. The selected
chemicals are distributed in two sets. The first set of 17 chemicals (14 sensitizers and 3 non sensitizers) which shall be
used for the prevalidation phase, are labelled “PRE” in Table 1 and included in Clause A.1. The second set of 12 chemicals (8
sensitizers and 4 non sensitizers) which shall be used for the interlaboratory study phase, are labelled “ILS” in Table 1 and
included in Clause A.2. The size of this set, 12 chemicals, represents half the number of chemicals originally used for the
validation of OECD test methods. It was considered appropriate from a statistical point of view because minor deviation of
the protocols during the feasibility study are unlikely to affect the transferability and interlaboratory reproducibility.
6
© ISO 2023 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/DTS 11796:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
S/NS Set Name CAS Application in the medical de- Spiking concen-
vice (MD) industry tration weight
per volume (w/v)
%
S ILS Isobornyl acrylate 5888–33–5 Plastic materials, valves, tubes 1
(IBOA) lining, stoppers, sealants, coatings,
inks, glues
Found in adhesives, wearable
devices such as glucose monitoring
sensors, insulin patch pumps and
some wound dressings
S ILS 2-Mercaptobenzothi- 149–30–4 Rubber accelerators 1,35
azole (MBT) Gloves
S ILS 2-hydroxyethyl acrylate 818–61–1 Acrylates, methacrylates and 1,4
monomers
Wound dressings, EKG electrodes,
Contact lenses
S ILS Nickel(II) sulfate hex- 10101–97–0 Nickel alloys and stainless steels in 4,8
ahydrate (NiSO4) 7786–81–4 implantable medical devices
S ILS Abietic acid 514–10–3 Adhesives 15
Wound dressing
S ILS α-Methylstyrene 98–83–9 Intermediate used in the manu- 46
facture of plasticizers, resins and
polymers
NS ILS Chlorobenzene 108–90–7 Intermediate in rubber, solvent in 1
adhesives
NS ILS Octanoic acid 124–07–2 Lubricant 1
NS ILS Glycerol 56–81–5 1
NS ILS Lactic Acid 50–21–5 Monomer of polymer polylactic 1
acid (PLA). PLA is commonly used
in biodegradable polymers for
drug delivery systems, tissue engi-
neering, temporary and long-term
implantable devices, etc.
Key
S sensitizer
NS non sensitizer
The database of reference chemicals contains 29 chemicals, 7 non sensitizers and 22 skin sensitizers. The selected
chemicals are distributed in two sets. The first set of 17 chemicals (14 sensitizers and 3 non sensitizers) which shall be
used for the prevalidation phase, are labelled “PRE” in Table 1 and included in Clause A.1. The second set of 12 chemicals (8
sensitizers and 4 non sensitizers) which shall be used for the interlaboratory study phase, are labelled “ILS” in Table 1 and
included in Clause A.2. The size of this set, 12 chemicals, represents half the number of chemicals originally used for the
validation of OECD test methods. It was considered appropriate from a statistical point of view because minor deviation of
the protocols during the feasibility study are unlikely to affect the transferability and interlaboratory reproducibility.
The selected chemicals are representative of chemicals previously found in leaching studies of medical
devices extracts (see Annex A). The skin sensitizers cover the different potency categories according
[16]
to the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) classification as
represented in Figure 2: 8 weak, 9 moderate, 3 strong and 2 extreme skin sensitizers.
7
© ISO 2023 – All rights reserved
---------------------- Page: 12 ----------------------
ISO/DTS 11796:2023(E)
Figure 2 — Distribution of EC3 values of the reference chemical skin sensitizers
The physicochemical properties considered relevant to skin sensitization in the supporting document
to Reference [1] are presented in Table 2 for the 29 chemicals selected compared to the 167 chemicals of
[13]
the OECD database .
Table 2 — Summary of the physicochemical property ranges that describe the chemical space of
the chemicals tested in this document and in Reference [1]
[1]
OECD guideline 497 This document
ISO/TS 11796
Property min. to max. min. to max.
MW (g/mol) [30,0 to 512,6] [30,0 to 348,4]
LogP [−3,9
...
FINAL
TECHNICAL ISO/DTS
DRAFT
SPECIFICATION 11796
ISO/TC 194
Biological evaluation of medical
Secretariat: DIN
devices — Requirements for
Voting begins on:
2023-01-19 interlaboratory studies to
demonstrate the applicability of
Voting terminates on:
2023-03-16
validated in vitro methods to assess
the skin sensitization of medical
devices
Évaluation biologique des dispositifs médicaux — Guide pour les
études interlaboratoires visant à démontrer l'applicabilité des
méthodes in-vitro validées pour évaluer la sensibilisation cutanée des
dispositifs médicaux
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/DTS 11796:2023(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 1 ----------------------
ISO/DTS 11796:2023(E)
FINAL
TECHNICAL ISO/DTS
DRAFT
SPECIFICATION 11796
ISO/TC 194
Biological evaluation of medical
Secretariat: DIN
devices — Requirements for
Voting begins on:
interlaboratory studies to
demonstrate the applicability of
Voting terminates on:
validated in vitro methods to assess
the skin sensitization of medical
devices
Évaluation biologique des dispositifs médicaux — Guide pour les
études interlaboratoires visant à démontrer l'applicabilité des
méthodes in-vitro validées pour évaluer la sensibilisation cutanée des
dispositifs médicaux
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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.
RECIPIENTS OF THIS DRAFT ARE INVITED TO
ISO copyright office
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
CP 401 • Ch. de Blandonnet 8
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
CH-1214 Vernier, Geneva
DOCUMENTATION.
Phone: +41 22 749 01 11
IN ADDITION TO THEIR EVALUATION AS
Reference number
Email: copyright@iso.org
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
ISO/DTS 11796:2023(E)
Website: www.iso.org
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN
DARDS TO WHICH REFERENCE MAY BE MADE IN
ii
© ISO 2023 – All rights reserved
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 2 ----------------------
ISO/DTS 11796:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Consideration on the process for demonstration of the applicability domain .3
5 Positive and negative control test samples . 4
5.1 General . 4
5.2 Database of reference chemicals . 5
5.3 Reference materials . 8
5.3.1 General . 8
5.3.2 Negative control medical device material . 9
5.3.3 Positive reference material . 9
6 Preparation of the test samples .9
6.1 General . 9
6.2 Preparation of the extracts . 9
6.3 Spiking of the extracts . 10
7 Prevalidation of candidate test methods .10
8 Interlaboratory study .11
8.1 General . 11
8.2 Study organization . 11
8.2.1 General . 11
8.2.2 Management team . 11
8.2.3 Lead laboratory . 11
8.2.4 Sample management . 11
8.2.5 Independent biostatistician . 11
8.3 Sample preparation . 11
8.4 Performance review .12
9 Statistical analysis .12
10 Test report .12
Annex A (informative) Reference chemicals .14
Bibliography .28
iii
© ISO 2023 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/DTS 11796:2023(E)
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 nongovernmental, 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 194, Biological and clinical evaluation of
medical devices.
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.
iv
© ISO 2023 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/DTS 11796:2023(E)
Introduction
International Standards can be used to demonstrate the safety and compliance of medical devices.
ISO 10993-10 specifies the procedure for the assessment of medical devices and their constituent
materials with regard to their potential to induce skin sensitization (Type IV hypersensitivity reaction).
The methods included in ISO 10993-10 are based on animal or human testing, with an annex on in vitro
and in chemico tests for skin sensitization that have been validated for neat chemicals. The effort to
reduce or replace the use of animals in toxicity testing has led to the development of many new non-
animal methods. The test guidelines in References [56] and [57] include alternatives to animal testing
methods for skin sensitization that have been previously validated to confirm their equivalence/
superiority to the current in vivo methods. However, currently, none of the OECD test guideline methods
are considered sufficient stand-alone replacements for in vivo tests that assess the skin sensitization
[1]
potential of chemicals .
Current OECD test guideline methods are validated with neat chemicals and not with more complex
mixtures such as medical devices or medical devices extracts. In order to use these methods in the
specific context of medical devices, an evaluation is needed to verify their applicability for assessing
skin sensitization of medical devices. Given the number of candidate test methods and the time that
is required to assess them, it is important to ensure that the same science-based evaluation process
and criteria are consistently applied to any new candidate test method. The purpose of this document
is to provide a framework for the conduct of prevalidation and interlaboratory studies to assess the
applicability of candidate test methods for assessing one or more key events related to OECD’s adverse
[2]
outcome pathway (AOP) for skin sensitization when evaluating medical devices .
v
© ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/DTS 11796:2023(E)
Biological evaluation of medical devices — Requirements
for interlaboratory studies to demonstrate the
applicability of validated in vitro methods to assess the
skin sensitization of medical devices
1 Scope
This document specifies the framework and the methodology to evaluate and demonstrate the
applicability of a validated non-animal method from an OECD test guideline to assess the skin sensitizing
potential of a medical device or a medical device material. This document addresses:
— database of reference chemical skin sensitizers and non sensitizers;
— reference materials;
— feasibility testing of candidate test methods, including any method optimization for use with
extracts of medical devices;
— prevalidation of candidate test methods;
— interlaboratory study:
— sample preparation and coding;
— spiking of the extracts of negative control medical device material;
— collection of the data;
— statistical analysis to assess reliability and reproducibility.
The use of the approaches described in this document to assess the applicability of a candidate test
method does not imply that the candidate test method can be used as stand-alone test for the evaluation
of skin sensitization potential of medical devices. For certain candidate test methods, integrated
[1]
approaches and/or defined approaches are needed. The evaluation of skin sensitization potential of a
medical device is described in ISO 1099310.
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 1099312, Biological evaluation of medical devices — Part 12: Sample preparation and reference
materials
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
1
© ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/DTS 11796:2023(E)
3.1
allergen
sensitizer
substance or material that is capable of inducing a specific hypersensitivity reaction upon repeated
contact with that substance or material
3.2
candidate test method
test method for in vitro sensitization testing of medical devices that is under evaluation
3.3
interlaboratory study
ILS
organization, performance and evaluation of measurements or tests on the same or similar items by
two or more laboratories according to predetermined conditions
3.4
interlaboratory reproducibility
between-laboratory reproducibility
measure of the extent to which different qualified laboratories, using the same protocol and testing the
same substances, can produce qualitatively and quantitatively similar results
Note 1 to entry: Interlaboratory reproducibility is determined during the prevalidation and validation processes,
[29]
and indicates the extent to which a test can be successfully transferred between laboratories.
3.5
intralaboratory reproducibility
within-laboratory reproducibility
determination of the extent that qualified people within the same laboratory can successfully replicate
results using a specific protocol at different times
3.6
prevalidation
PRE
initial phase of a validation (3.10) small-scale study intended to obtain preliminary information on the
relevance and reliability of a candidate test method (3.2)
3.7
test article
material (e.g. a final finished device or a reference material) that is to be used to generate a test sample
(3.8) (e.g. using extraction)
3.8
test sample
sample (e.g. a test article extract or spiked extract vehicle) that in its present form can be evaluated by
a candidate test method
3.9
test system
system (e.g. in vivo animal model, in vitro cellular model and in-silico computational models) that is
used for hazard identification as part of a test method
3.10
validation
confirmation, through the provision of objective evidence, that the requirements for a specific intended
use or application have been fulfilled
[SOURCE: ISO 9000:2015, 3.8.13, modified — Notes 1, 2 and 3 to entry have been deleted.]
2
© ISO 2023 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/DTS 11796:2023(E)
4 Consideration on the process for demonstration of the applicability domain
The process for evaluating the applicability of a candidate test method for sensitization testing of
medical devices shall include feasibility, prevalidation and interlaboratory studies (see Figure 1).
Prior to conducting a prevalidation study, a feasibility study may be needed to determine if any
modification of the OECD TG protocols (e.g. dilution, solvents, incubation times, volume of test sample,
stimulation index value) is necessary for the evaluation of medical devices.
Protocols for feasibility studies are not described in this document as the design of these studies should
be specific to the OECD TG method.
If the candidate test method protocols planned for the prevalidation and interlaboratory studies
deviate from the OECD TG protocol, the number and nature of the modifications as well as the data and
documentation available (e.g. from a feasibility study) to support the modifications shall be provided.
A scientific rationale for the impact of these changes on the acceptance of the method for assessing
the sensitizing potential of sample tests should be provided to justify that the method used remains
equivalent to the original OECD method.
The same candidate test method and protocols shall be used for both the prevalidation study and the
interlaboratory study.
As the non-animal methods considered are already validated with single chemicals (but not with
mixtures such as medical devices extracts) and integrated in OECD test guidelines (e.g. see Reference
[91] and Reference [1] on defined approaches for sensitization) with historical data of chemicals
assessment, the prevalidation step shall be conducted to:
a) prepare the standard operating procedures (SOPs), so that they can be readily used by other
laboratories;
b) generate preliminary data on the reliability and relevance of the candidate test method for
assessing skin sensitization of medical devices.
During the prevalidation and interlaboratory phases, evaluation of the performance of non-animal
methods shall be performed with positive and negative control test samples (in accordance with
Clause 5) that are representative of medical devices extracts. The accuracy, sensitivity, specificity and
reproducibility shall be calculated and compared to the targeted performance values in Clause 7 and
Clause 8.
If the prevalidation study does not achieve the performance criteria in accordance with Clause 7, then
additional feasibility testing may be needed to optimize the assay protocol for increased accuracy,
specificity and/or intralaboratory reproducibility prior to conducting a repeat prevalidation study.
If the prevalidation study meets the performance criteria in accordance with Clause 7, then an
interlaboratory study can be considered.
3
© ISO 2023 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/DTS 11796:2023(E)
Figure 1 — General process for the evaluation of candidate test methods
5 Positive and negative control test samples
5.1 General
Due to the lack of existing positive reference test articles, samples for prevalidation and interlaboratory
studies comprise negative reference material extracts spiked with a known concentration of a chemical
skin sensitizer. By spiking an extract of an existing medical device material, the final composition of
4
© ISO 2023 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/DTS 11796:2023(E)
test samples tested by candidate in vitro test methods can better mimic the chemical complexity of a
real extract containing a low concentration of one or more chemical skin sensitizers.
For this purpose, chemical skin sensitizers and non sensitizers that can be identified in extracts of
certain medical device materials have been selected. Annex A includes animal, and human data when
available, to serve as a reference database for prevalidation and interlaboratory studies.
5.2 Database of reference chemicals
A list of reference chemicals was developed including chemicals:
— representative of raw materials and/or leachables found in medical devices;
— representative of a balanced range of skin sensitizer potency (weak, moderate and strong);
— supported by robust reference data on potency and no-observed-adverse-effect-levels (NOAELs)
from human and animal sources, including human repeat insult patch test (HRIPT), human
maximization test (HMT), local lymph node assay (LLNA), closed-patch (Buehler) test and guinea-
pig maximization test (GPMT).
Additional criteria considered for selection of chemicals are:
— to be representative of the different mechanisms by which the compounds exert a sensitization
effect;
— a range of physicochemical properties considered relevant to skin sensitization in Reference [1];
— commercially available compounds.
NOTE The selection of chemicals already detected in medical devices or medical device materials was based
[3][4][5][6][7]
on a review of the scientific literature. Particular attention was paid to the quality of the historical
toxicological data for these chemicals. The estimated concentrations required to generate a threefold stimulation
[8]
of proliferation in draining lymph node (EC3 values) are derived from curated databases such as SkinSenseDB,
[9]
the Cosmetics Europe database, supplementary data from Reference [10], the integrated chemical environment
[11]
(ICE) from the national toxicology program (NTP), the National Toxicology Program Interagency Centre
[12]
for the Evaluation of Alternative Toxicological Methods (NICEATM) LLNA Database and the OECD curated
[13][14][15]
database for OECD guideline 497 .
®1)
All chemicals are presented in Table 1 with name, CAS Registry Number , medical devices application
examples and the spiking concentration to be used for prevalidation and interlaboratory studies.
Additional information on their physicochemical and skin sensitizing properties in humans and
animals is presented in Annex A (e.g. GPMT, LLNA EC3, human potency, reference publications and
complementary data).
®
1) CAS Registry Number is a trademark of CAS corporation. This information is given for the convenience of users
of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be
used if they can be shown to lead to the same results.
5
© ISO 2023 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/DTS 11796:2023(E)
Table 1 — Database of reference chemicals for PRE and ILS
S/NS Set Name CAS Application in the medical de- Spiking concen-
vice (MD) industry tration weight
per volume (w/v)
%
S PRE Glutaraldehyde 111–30–8 Disinfectant and crosslinker for 0,08
animal derived tissue product
S PRE 1,4-Phenylenediamine 106–50–3 0,11
S PRE Phthalic anhydride 85–44–9 0,16
S PRE Cobalt chloride 7646–79–9 Orthopaedic implants, stents, 0,4
pacemakers
S PRE Phenylacetaldehyde 122–78–1 3
S PRE Hydratropic aldehyde 93–53–8 6,3
S PRE Methyl oleate 112–62–9 Ink, lubricants, etc. 8,5
S PRE Linolenic acid 463–40–1 Lubricants 9,9
S PRE Ethyl acrylate 140–88–5 Acrylates, methacrylates and 10
monomers
Found in adhesives, wearable de
vices, wound dressings
S PRE TPO (Diphenyl(2,4,6-tri 75980–60–8 Photoinitiator for additive man 27
methylbenzoyl)phos ufacturing in many light-cured
phine oxide) acrylic polymers) such as compos
ite materials, dental fillers, etc.
S PRE 2,4,7,9Tetrame 126–86–3 Plastic and rubber products 34,3
thyl-5-decyn-4,7-diol
S PRE Isopropyl Myristate 110–27–0 Plasticizer, lubricant 44
S PRE Tridecane 629–50–5 solvent, rubber industry 48,4
S PRE Methyl methacrylate 80–62–6 Bone cement, dental materials, 75
hearing aids
NS PRE Diethyl phtalate 84–66–2 Solvent, plasticizer, extractable 1
associated with polyethylene and
PET
NS PRE 1,3-diphenylguanidine 102–06–7 Rubber accelerators 1
Found in gloves
NS PRE Zinc oxide 1314–13–2 Anti-bacterial and anti-biofilm 1
activity
S ILS 2,4Dinitrochloroben 97–00–7 0,06
zen DNCB
S ILS Formaldehyde (act. 50–00–0 Sterilizationlow temperature 0,3
37 %) steam and formaldehyde (LTSF)
Key
S sensitizer
NS non sensitizer
The database of reference chemicals contains 29 chemicals, 7 non sensitizers and 22 skin sensitizers. The selected
chemicals are distributed in two sets. The first set of 17 chemicals (14 sensitizers and 3 non sensitizers) which shall be
used for the prevalidation phase, are labelled “PRE” in Table 1 and included in Clause A.1. The second set of 12 chemicals (8
sensitizers and 4 non sensitizers) which shall be used for the interlaboratory study phase, are labelled “ILS” in Table 1 and
included in Clause A.2. The size of this set, 12 chemicals, represents half the number of chemicals originally used for the
validation of OECD test methods. It was considered appropriate from a statistical point of view because minor deviation of
the protocols during the feasibility study are unlikely to affect the transferability and interlaboratory reproducibility.
6
© ISO 2023 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/DTS 11796:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
S/NS Set Name CAS Application in the medical de- Spiking concen-
vice (MD) industry tration weight
per volume (w/v)
%
S ILS Isobornyl acrylate 5888–33–5 Plastic materials, valves, tubes 1
(IBOA) lining, stoppers, sealants, coatings,
inks, glues
Found in adhesives, wearable
devices such as glucose monitoring
sensors, insulin patch pumps and
some wound dressings
S ILS 2Mercaptobenzothi 149–30–4 Rubber accelerators 1,35
azole (MBT) Gloves
S ILS 2-hydroxyethyl acrylate 818–61–1 Acrylates, methacrylates and 1,4
monomers
Wound dressings, EKG electrodes,
Contact lenses
S ILS Nickel(II) sulfate hex 10101–97–0 Nickel alloys and stainless steels in 4,8
ahydrate (NiSO4) 7786–81–4 implantable medical devices
S ILS Abietic acid 514–10–3 Adhesives 15
Wound dressing
S ILS α-Methylstyrene 98–83–9 Intermediate used in the manu 46
facture of plasticizers, resins and
polymers
NS ILS Chlorobenzene 108–90–7 Intermediate in rubber, solvent in 1
adhesives
NS ILS Octanoic acid 124–07–2 Lubricant 1
NS ILS Glycerol 56–81–5 1
NS ILS Lactic Acid 50–21–5 Monomer of polymer polylactic 1
acid (PLA). PLA is commonly used
in biodegradable polymers for
drug delivery systems, tissue engi
neering, temporary and long-term
implantable devices, etc.
Key
S sensitizer
NS non sensitizer
The database of reference chemicals contains 29 chemicals, 7 non sensitizers and 22 skin sensitizers. The selected
chemicals are distributed in two sets. The first set of 17 chemicals (14 sensitizers and 3 non sensitizers) which shall be
used for the prevalidation phase, are labelled “PRE” in Table 1 and included in Clause A.1. The second set of 12 chemicals (8
sensitizers and 4 non sensitizers) which shall be used for the interlaboratory study phase, are labelled “ILS” in Table 1 and
included in Clause A.2. The size of this set, 12 chemicals, represents half the number of chemicals originally used for the
validation of OECD test methods. It was considered appropriate from a statistical point of view because minor deviation of
the protocols during the feasibility study are unlikely to affect the transferability and interlaboratory reproducibility.
The selected chemicals are representative of chemicals previously found in leaching studies of medical
devices extracts (see Annex A). The skin sensitizers cover the different potency categories according
[16]
to the Europe
...
ISO/DTS 11796:2022(X2023(E)
ISO/TC 194/WG 8
Date: YYYY-MM-DD
Secretariat: DIN
Biological evaluation of medical devices —
Requirements for interlaboratory studies to demonstrate the
applicability of validated in vitro methods to assess the skin sensitization of medical
devices
DTS stage
Warning for WDs and CDs
This document is not an ISO International Standard. It is distributed for review and comment. It is subject to change
without notice and may not be referred to as an International Standard.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which
they are aware and to provide supporting documentation.
© ISO 2021 – All rights reserved
---------------------- Page: 1 ----------------------
© ISO 20XX
First edition
Date: 2023-01-04
---------------------- Page: 2 ----------------------
ISO/DTS 11796:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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’sISO's member body in
the country of the requester.
ISO Copyright Office
CP 401 • CH. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Email: copyright@iso.org copyright@iso.org
Website: www.iso.orgwww.iso.org
Published in Switzerland.
iv © ISO 2023 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/DTS 11796:2023(E)
Contents
Foreword . 6
Introduction . 7
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Consideration on the process for demonstration of the applicability domain . 3
5 Positive and Negative Control Test Samples . 7
5.1 Database of reference chemicals . 7
5.2 Reference materials . 12
5.2.1 Negative control medical device material . 12
5.2.2 Positive reference material . 12
6 Preparation of the test samples . 13
6.1 Preparation of the extracts . 13
6.2 Spiking of the extracts. 13
7 Prevalidation of candidate test methods . 14
8 Interlaboratory study . 14
8.1 Study organization . 15
8.1.1 General . 15
8.1.2 Management team . 15
8.1.3 Lead laboratory . 15
8.1.4 Sample management . 15
8.1.5 Independent biostatistician . 15
8.2 Sample preparation . 15
8.3 Performance review . 16
9 Statistical analysis . 16
10 Test report . 16
Annex A (informative) Reference chemicals . 18
Bibliography . 34
© ISO 2023 – All rights reserved v
---------------------- Page: 4 ----------------------
ISO/DTS 11796:2023(E)
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 194, Biological and clinical evaluation of
medical devices, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 206, Biological and clinical evaluation of medical devices, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 10993 series can be found on the ISO website.
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.
vi © ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
ISO/DTS 11796:2023(E)
Introduction
International Standards can be used to demonstrate the safety and compliance of medical devices. ISO
10993-10 specifies the procedure for the assessment of medical devices and their constituent materials
with regard to their potential to induce skin sensitization (Type IV hypersensitivity reaction). The
methods included in ISO 10993-10 are based on animal or human testing, with an informative annex on
in vitro and in chemico tests for skin sensitization that have been validated for neat chemicals. The effort
to reduce or replace the use of animals in toxicity testing has led to the development of many new non-
animal methods. The OECD test guidelines in the 442 seriesReferences [56] and [57] include alternatives
to animal testing methods for skin sensitization that have been previously validated to confirm their
equivalence/superiority to the current in vivo methods. However, currently, none of the OECD test
guideline methods are considered sufficient stand-alone replacements for in vivo tests that assess the
[1]
skin sensitization potential of chemicals. .
Current OECD test guideline methods are validated with neat chemicals and not with more complex
mixtures such as medical devices or medical devices extracts. In order to use these methods in the specific
context of medical devices, an evaluation is needed to verify their applicability for assessing skin
sensitization of medical devices. Given the number of candidate test methods and the time that is required
to assess them, it is important to ensure that the same science-based evaluation process and criteria are
consistently applied to any new candidate test method. The purpose of this document is to provide a
framework for the conduct of prevalidation and interlaboratory studies to assess the applicability of
candidate test methods for assessing one or more key events related to OECD’s adverse outcome pathway
[2]
(AOP) for skin sensitization when evaluating medical devices. .
© ISO 2023 – All rights reserved vii
---------------------- Page: 6 ----------------------
TECHNICAL SPECIFICATION ISO/DTS 11796:2023(E)
NOTE For a candidate test method evaluated per this document to be
considered for inclusion in ISO 10993-10, the test report can be
submitted to ISO/TC 194/WG 8.Biological evaluation of medical
devices — Requirements for interlaboratory studies to demonstrate
the applicability of validated in vitro methods to assess the skin
sensitization of medical devices
1 Scope
This document specifies the framework and the methodology to evaluate and demonstrate the
applicability of a validated non-animal method from an OECD test guideline to assess the skin sensitizing
potential of a medical device or a medical device material. This document addresses:
— database of reference chemical skin sensitizers and non -sensitizers;
— reference materials;
— feasibility testing of candidate test methods, including any method optimization for use with extracts
of medical devices;
— prevalidation of candidate test methods;
— interlaboratory study:
— sample preparation and coding;
— spiking of the extracts of negative control medical device material;
— collection of the data;
— statistical analysis to assess reliability and reproducibility.
The use of the approaches described in this document to assess the applicability of a candidate test
method does not imply that the candidate test method can be used as stand-alone test for the evaluation
of skin sensitization potential of medical devices. For certain candidate test methods, integrated
[1]
approaches and/or defined approaches may beare needed. The evaluation of skin sensitization
potential of a medical device is described in ISO 10993:-10.
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 10993-12:2021, Biological evaluation of medical devices — Part 12: Sample preparation and reference
materials
© ISO 2023 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO/DTS 11796:2023(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminologicalterminology databases for use in standardization at the following
addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
allergen
sensitizer
substance or material that is capable of inducing a specific hypersensitivity reaction upon repeated
contact with that substance or material
3.2
allergic contact dermatitis
clinical diagnosis based on an observed immunologically-mediated cutaneous reaction to a substance
3.3
candidate test method
test method for in vitro sensitization testing of medical devices that is under evaluation
3.43
interlaboratory study
round robin study
ILS
organization, performance and evaluation of measurements or tests on the same or similar items by two
or more laboratories in accordance withaccording to predetermined conditions
3.4
interlaboratory reproducibility
between-laboratory reproducibility
measure of the extent to which different qualified laboratories, using the same protocol and testing the
same substances, can produce qualitatively and quantitatively similar results
Note 1 to entry: Interlaboratory reproducibility is determined during the prevalidation and validation processes,
[29]
and indicates the extent to which a test can be successfully transferred between laboratories.
3.5
intralaboratory studyreproducibility
organization, performance and evaluationwithin-laboratory reproducibility
determination of measurements or tests on the same or similar itemsextent that qualified people within
the same laboratory in accordance with predetermined conditionscan successfully replicate results using
a specific protocol at different times
3.6
prevalidation
PRE
initial phase of a validation study;(3.10) small-scale study intended to obtain preliminary information on
the relevance and reliability of a candidate test method (3.2)
3.7
2 © ISO 2023 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/DTS 11796:2023(E)
test article
material (e.g.,. a final finished device or a reference material) that is to be used to generate a test sample
(3.8) (e.g.,. using extraction)
3.8
test sample
sample (e.g.,. a test article extract or spiked extract vehicle) that in its present form can be evaluated by a
candidate test method
3.9
test system
system (e.g.,. in vivo animal model, in vitro cellular model, and in-silico computational models) that is
used for hazard identification as part of a test method
3.10
validation
confirmation, through the provision of objective evidence, that the requirements for a specific intended
use or application have been fulfilled
[SOURCE: ISO 9000:2015, 3.8.13, modified – Note— Notes 1, 2 and 3 to entry hashave been deleted.]
4 Consideration on the process for demonstration of the applicability domain
The process for evaluating the applicability of a candidate test method for sensitization testing of medical
devices shall include feasibility, prevalidation, and interlaboratory studies (see Figure 1).
Prior to conducting a prevalidation study, a feasibility study may be needed to determine if any
modification of the OECD TG protocols (e.g. dilution, solvents, incubation times, volume of test sample,
stimulation index value) is necessary for the evaluation of medical devices.
Protocols for feasibility studies are not described in this document as the design of these studies should
be specific to the OECD TG method.
If the candidate test method protocols planned for the prevalidation and interlaboratory studies deviate
from the OECD TG protocol, the number and nature of the modifications as well as the data and
documentation available (e.g. from a feasibility study) to support the modifications shall be provided. A
scientific rationale for the impact of these changes on the acceptance of the method for assessing the
sensitizing potential of sample tests should be provided to justify that the method used remains
equivalent to the original OECD method.
The same candidate test method and protocols shall be used for both the prevalidation study and the
interlaboratory study.
As the non-animal methods considered are already validated with single chemicals (but not with mixtures
such as medical devices extracts) and integrated in OECD test guidelines (e.g., OECD 442 series. see
Reference [91] and OECD guideline 497Reference [1] on defined approaches for sensitization) with
historical data of chemicals assessment, the prevalidation step shall be conducted to:
a) prepare the standard operating procedures (SOPs), so that they can be readily used by other
laboratories;
b) generate preliminary data on the reliability and relevance of the candidate test method for assessing
skin sensitization of medical devices.
© ISO 2023 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO/DTS 11796:2023(E)
During the prevalidation and interlaboratory phases, evaluation of the performance of non-animal
methods shall be performed with positive and negative control test samples (in accordance with Clause 5)
that are representative of medical devices extracts. The accuracy, sensitivity, specificity and
reproducibility shall be calculated and compared to the targeted performance values in Clause 7 and
Clause 8.
If the prevalidation study does not achieve the performance criteria in accordance with Clause 7, then
additional feasibility testing may be needed to optimize the assay protocol for increased accuracy,
specificity, and/or intralaboratory reproducibility prior to conducting a repeat prevalidation study. If the
prevalidation study meets the performance criteria in accordance with Clause 7, then an interlaboratory
study can be considered.
4 © ISO 2023 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/DTS 11796:2023(E)
© ISO 2023 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO/DTS 11796:2023(E)
Figure 1 — General process for the evaluation of candidate test methods
6 © ISO 2023 – All rights reserved
---------------------- Page: 12 ----------------------
ISO/DTS 11796:2023(E)
5 Positive and negative control test samples
5.1 General
Due to the lack of existing positive reference materialstest articles, samples for prevalidation and
interlaboratory studies are comprised ofcomprise negative reference material extracts spiked with a
known concentration of a chemical skin sensitizer. By spiking an extract of an existing medical device
material, the final composition of test samples tested by candidate in vitro test methods can better mimic
the chemical complexity of a real extract containing a low concentration of one or more chemical skin
sensitizers.
For this purpose, chemical skin sensitizers and non -sensitizers that can be identified in extracts of certain
medical device materials have been selected. Annex A includes animal, and human data when available,
to serve as a reference database for prevalidation and interlaboratory studies.
5.15.2 Database of reference chemicals
A list of reference chemicals was developed including chemicals:
— representative of raw materials and/or leachables found in medical devices;
— representative of a balanced range of skin sensitizer potency (weak, moderate, and strong);
— supported by robust reference data on potency and no-observed-adverse-effect-levels (NOAELs)
from human and animal sources, including human repeat insult patch test (HRIPT), human
maximization test (HMT), local lymph node assay (LLNA), closed-patch (Buehler) test, and guinea-
pig maximization test (GPMT).
Additional criteria considered for selection of chemicals are:
— to be representative of the different mechanisms by which the compounds exert a sensitization effect;
— a range of physicochemical properties considered relevant to skin sensitization in the supporting
document to the OECD guideline 497;Reference [1];
— commercially available compounds.
NOTE The selection of chemicals already detected in medical devices or medical device materials was based on a
[3][4][5][6][7]
review of the scientific literature. Particular attention was paid to the quality of the historical toxicological
data for these chemicals. The estimated concentrations required to generate a threefold stimulation of proliferation
[8]
in draining lymph node (EC3 values) are derived from curated databases such as SkinSenseDB,, the Cosmetics
[9]
Europe database,, supplementary data from Urbish et al ,Reference [10], the integrated chemical environment
[11]
(ICE) from the national toxicology program (NTP),), the National Toxicology Program Interagency Centre for the
[12]
Evaluation of Alternative Toxicological Methods (NICEATM) LLNA Database and the OECD curated database for
[13][14][15]
OECD guideline 497. .
1
®
All chemicals are presented in Table 1 with name, CAS numberRegistry Number , medical devices
application examples and the spiking concentration to be used for prevalidation and interlaboratory
studies. Additional information on their physicochemical and skin sensitizing properties in
humanhumans and animalanimals is presented in Annex A (e.g. GPMT, LLNA EC3, human potency,
reference publications and complementary data).
1
®
CAS Registry Number is a trademark of CAS corporation. This information is given for the convenience of users of this
document and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they
can be shown to lead to the same results.
© ISO 2023 – All rights reserved 7
---------------------- Page: 13 ----------------------
ISO/DTS 11796:2023(E)
Table 1 — Database of reference chemicals for prevalidation (PRE) and interlaboratory studies
(ILS)
8 © ISO 2023 – All rights reserved
---------------------- Page: 14 ----------------------
ISO/DTS 11796:2023(E)
S/NS Set Name CAS Application in the medical Spiking
device (MD) industry concentration
weight per
volume (w/v)
%
S PRE Glutaraldehyde 111–30–8 Disinfectant and crosslinker for 0,08
animal derived tissue product
S PRE 1,4-Phenylenediamine 106–50–3 0,11
S PRE Phthalic anhydride 85–44–9 0,16
S PRE Cobalt chloride 7646–79–9 Orthopaedic implants, stents, 0,4
pacemakers
S PRE Phenylacetaldehyde 122–78–1 3
S PRE Hydratropic aldehyde 93–53–8 6,3
S PRE Methyl oleate 112–62–9 Ink, lubricants, etc. 8,5
S PRE Linolenic acid 463–40–1 Lubricants 9,9
S PRE Ethyl acrylate 140–88–5 Acrylates, methacrylates and 10
monomers
Found in adhesives, wearable
devices, wound dressings
S PRE TPO (Diphenyl(2,4,6- 75980–60–8 Photo-initiator for additive 27
trimethylbenzoyl)phos manufacturing in many light-
phine oxide) cured acrylic polymers) such as
composite materials, dental
fillers, etc.
S PRE 2,4,7,9-Tetramethyl-5- 126–86–3 Plastic and rubber products 34,3
decyn-4,7-diol
S PRE Isopropyl Myristate 110–27–0 Plasticizer, lubricant 44
S PRE Tridecane 629–50–5 solvent, rubber industry 48,4
S PRE Methyl methacrylate 80–62–6 Bone cement, dental materials, 75
hearing aids
NS PRE Diethyl phtalate 84–66–2 Solvent, plasticizer, extractable 1
associated with polyethylene and
PET
NS PRE 1,3-diphenylguanidine 102–06–7 Rubber accelerators 1
Found in gloves
NS PRE Zinc oxide 1314–13–2 Anti-bacterial and anti-biofilm 1
activity
S ILS 2,4- 97–00–7 0,06
Dinitrochlorobenzen
DNCB
S ILS Formaldehyde (act. 50–00–0 Sterilization-low temperature 0,3
37 %) steam and formaldehyde (LTSF)
© ISO 2023 – All rights reserved 9
---------------------- Page: 15 ----------------------
ISO/DTS 11796:2023(E)
S ILS Isobornyl acrylate 5888–33–5 Plastic materials, valves, tubes 1
(IBOA) lining, stoppers, sealants,
coatings, inks, glues
Found in adhesives, wearable
devices such as glucose
monitoring sensors, insulin patch
pumps and some wound
dressings
S ILS 2- 149–30–4 Rubber accelerators 1,35
Mercaptobenzothiazol Gloves
e (MBT)
S ILS 2-hydroxyethyl 818–61–1 Acrylates, methacrylates and 1,4
acrylate monomers
Wound dressings, EKG electrodes,
Contact lenses
S ILS Nickel(II) sulfate 10101–97–0 Nickel alloys and stainless steels 4,8
hexahydrate (NiSO4) 7786–81–4 in implantable medical devices
S ILS Abietic acid 514–10–3 Adhesives 15
Wound dressing
S ILS α-Methylstyrene 98–83–9 Intermediate used in the 46
manufacture of plasticizers,
resins and polymers
NS ILS Chlorobenzene 108–90–7 Intermediate in rubber, solvent in 1
adhesives
NS ILS Octanoic acid 124–07–2 Lubricant 1
NS ILS Glycerol 56–81–5 1
NS ILS Lactic Acid 50–21–5 Monomer of polymer polylactic 1
acid (PLA). PLA is commonly used
in biodegradable polymers for
drug delivery systems, tissue
engineering, temporary and long-
term implantable devices, etc.
Key
S sensitizer
NS non sensitizer
The database of reference chemicals contains 29 chemicals, 7 non sensitizers and 22 skin sensitizers. The selected chemicals
are distributed in two sets. The first set of 17 chemicals (14 sensitizers and 3 non sensitizers) which shall be used for the
prevalidation phase, are labelled “PRE” in Table 1 and included in Clause A.1. The second set of 12 chemicals (8 sensitizers
and 4 non sensitizers) which shall be used for the interlaboratory study phase, are labelled “ILS” in Table 1 and included in
Clause A.2. The size of this set, 12 chemicals, represents half the number of chemicals originally used for the validation of
OECD test methods. It was considered appropriate from a statistical point of view because minor deviation of the protocols
during the feasibility study are unlikely to affect the transferability and interlaboratory reproducibility.
The selected chemicals are representative of chemicals previously found in leaching studies of medical
devices extracts (see Annex A). The skin sensitizers cover the different potency categories according to
[16]
the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) classification as
represented in Figure 2: 8 weak, 9 moderate, 3 strong and 2 extreme skin sensitizers.
10 © ISO 2023 – All rights reserved
---------------------- Page: 16 ----------------------
ISO/DTS 11796:2023(E)
Figure 2 — Distribution of EC3 values of the reference chemical skin sensitizers
The physicochemical properties considered relevant to skin sensitization in the supporting document to
the OECD guideline 497Reference [1] are presented in Table 2 for the 29 chemicals selected compared to
[13]
the 167 chemicals of the OECD database. .
Table 2 — Summary of the physicochemical property ranges that describe the chemical space of
the chemicals tested in this document and in the OECD guideline 497Reference [1]
© ISO 2023 – All rights reserved 11
---------------------- Page: 17 ----------------------
ISO/DTS 11796:2023(E)
[1]
OECD guideline 497 ISO/TS 11796
Property min to max min to max
MW (g/mol) [30,0 to 512,6] [30,0 to 348,4]
LogP [−3,9 to 9,4] [−1,8 to 7,5]
LogWS (mol/l) [−7,6 to 1,2] [−7,6 to 1,2]
MP (°C) [−122,5 to 252,7] [−105 to 411]
BP (°C) [−19,1 to 445,3] [−19,1 to 1 000]
LogVP [−18,7 to 11,6] [−8,5 to 2,916]
Key
MW molecular weight
BP boiling point
MP melting point
LogVP vapour pressure
LogP octanol-water partition coefficient
LogWS water solubility
5.25.3 Reference materials
5.3.1 General
In order to reproduce the real-life conditions of a medical device evaluation, a negative control medical
device material shall be extracted under the usual extraction conditions used in an in vivo test. The
negative control medical device material shall be a material commonly used in medical devices and
known to release a complex mixture of non-sensitizing chemicals representative of a medical device
extract. The polar and non-polar extracts of this negative control medical device material shall then be
spiked with the skin sensitizing or non-sensitizing chemicals to perform the evaluation.
5.2.15.3.2 Negative control medical device material
The negative control medical device material shall be a silicone available commercially and known to
release numerous compounds without eliciting a positive sensitization response. MED-2000 silicone
2
supplied by Nusil Technology shouldcan be used as negative control medical device material. Use of any
alternative negative control medical device material shall be described and justified. After extraction
according to ISO 10993-12, the extracts shall be used as a negative control and for preparing the test
samples by spiking these extracts with skin sensitizing and non-sensitizing chemicals.
5.2.25.3.3 Positive reference material
If a positive certified reference material supported by animal or human data is avai
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.