oSIST prEN ISO 23977-1:2021
(Main)Plastics - Determination of the aerobic biodegradation of plastic materials exposed to seawater - Part 1: Method by analysis of evolved carbon dioxide (ISO 23977-1:2020)
Plastics - Determination of the aerobic biodegradation of plastic materials exposed to seawater - Part 1: Method by analysis of evolved carbon dioxide (ISO 23977-1:2020)
This document specifies a laboratory test method for determining the degree and rate of the aerobic biodegradation level of plastic materials. Biodegradation is determined by measuring the CO2 evolved from plastic materials when exposed to seawater sampled from coastal areas under laboratory conditions.
The conditions described in this document might not always correspond to the optimum conditions for the maximum degree of biodegradation, however this test method is designed to give an indication of the potential biodegradability of plastic materials.
NOTE This document addresses plastic materials but can also be used for other materials.
Kunststoffe - Bestimmung des aeroben Bioabbaus von Meerwasser ausgesetzten Kunststoff-Materialien - Teil 1: Verfahren mittels Analyse des freigesetzten Kohlenstoffdioxids (ISO 23977 1:2020)
Plastiques - Détermination de la biodégradation aérobie des matières plastiques exposées à l'eau de mer - Partie 1: Méthode par analyse du dioxyde de carbone dégagé (ISO 23977-1:2020)
Polimerni materiali - Določanje aerobne biorazgradljivosti polimernih materialov, izpostavljenih morski vodi - 1. del: Metoda z analizo sproščenega ogljikovega dioksida (ISO 23977-1:2020)
General Information
Standards Content (sample)
SLOVENSKI STANDARD
oSIST prEN ISO 23977-1:2021
01-september-2021
Polimerni materiali - Določanje aerobne biorazgradljivosti polimernih materialov,
izpostavljenih morski vodi - 1. del: Metoda z analizo sproščenega ogljikovegadioksida (ISO 23977-1:2020)
Plastics - Determination of the aerobic biodegradation of plastic materials exposed to
seawater - Part 1: Method by analysis of evolved carbon dioxide (ISO 23977-1:2020)
Kunststoffe - Bestimmung des aeroben Bioabbaus von Meerwasser ausgesetztenKunststoff-Materialien - Teil 1: Verfahren mittels Analyse des freigesetzten
Kohlenstoffdioxids (ISO 23977 1:2020)
Plastiques - Détermination de la biodégradation aérobie des matières plastiques
exposées à l'eau de mer - Partie 1: Méthode par analyse du dioxyde de carbone dégagé
(ISO 23977-1:2020)Ta slovenski standard je istoveten z: prEN ISO 23977-1
ICS:
13.020.40 Onesnaževanje, nadzor nad Pollution, pollution control
onesnaževanjem in and conservation
ohranjanje
83.080.01 Polimerni materiali na Plastics in general
splošno
oSIST prEN ISO 23977-1:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 23977-1:2021
INTERNATIONAL ISO
STANDARD 23977-1
First edition
2020-11
Plastics — Determination of the
aerobic biodegradation of plastic
materials exposed to seawater —
Part 1:
Method by analysis of evolved carbon
dioxide
Plastiques — Détermination de la biodégradation aérobie des
matières plastiques exposées à l'eau de mer —
Partie 1: Méthode par analyse du dioxyde de carbone dégagé
Reference number
ISO 23977-1:2020(E)
ISO 2020
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oSIST prEN ISO 23977-1:2021
ISO 23977-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
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
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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oSIST prEN ISO 23977-1:2021
ISO 23977-1:2020(E)
Contents Page
Foreword ........................................................................................................................................................................................................................................iv
Introduction ..................................................................................................................................................................................................................................v
1 Scope ................................................................................................................................................................................................................................. 1
2 Normative references ...................................................................................................................................................................................... 1
3 Terms and definitions ..................................................................................................................................................................................... 1
4 Principle ........................................................................................................................................................................................................................ 3
5 Test environment ................................................................................................................................................................................................. 3
6 Reagents ........................................................................................................................................................................................................................ 3
7 Apparatus ..................................................................................................................................................................................................................... 4
8 Procedure..................................................................................................................................................................................................................... 5
8.1 Test material ............................................................................................................................................................................................. 5
8.2 Reference materials ............................................................................................................................................................................ 5
8.3 Test set up ................................................................................................................................................................................................... 6
8.4 Pre-conditioning phase .................................................................................................................................................................... 6
8.5 Start of the test ........................................................................................................................................................................................ 6
8.6 Carbon dioxide measurement .................................................................................................................................................... 7
8.7 End of the test .......................................................................................................................................................................................... 7
9 Calculation and expression of results ............................................................................................................................................. 8
9.1 Calculation .................................................................................................................................................................................................. 8
9.1.1 Amount of CO produced .......................................................................................................................................... 8
9.1.2 Percentage of biodegradation............................................................................................................................10
9.2 Visual inspection ................................................................................................................................................................................11
9.3 Expression and interpretation of results ......................................................................................................................11
10 Validity of results ..............................................................................................................................................................................................11
11 Test report ................................................................................................................................................................................................................12
Annex A (informative) Example of a respirometric system .......................................................................................................13
Bibliography .............................................................................................................................................................................................................................15
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oSIST prEN ISO 23977-1:2021
ISO 23977-1:2020(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 61, Plastics, Subcommittee SC 14,
Environmental aspects.A list of all parts in the ISO 23997 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.iv © ISO 2020 – All rights reserved
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ISO 23977-1:2020(E)
Introduction
According to the United Nations Environment Program (UNEP), one of the most notable properties of
synthetic polymers and plastics is their durability which, combined with their accidental loss, deliberate
release and poor waste management has resulted in the ubiquitous presence of plastic in oceans (UNEP,
[16]2015 ).
It is well known and documented that marine litter can pose risks and a negative impact on living
marine organisms and on human beings. Degradability of plastic materials exposed to the marine
environment is one of the factors affecting impact and strength of effects. The uncontrolled dispersion
of biodegradables plastics in natural environments is not desirable. The biodegradability of products
cannot be considered as an excuse to spread wastes that should be recovered and recycled. However,
test methods to measure rate and level of biodegradation in natural environments are of interest in
order to better characterize the behaviour of plastics in these very particular environments. Thus, the
degree and rate of biodegradation is of major interest in order to obtain an indication of the potential
biodegradability of plastic materials when exposed to different marine habitats.ISO/TC 61/SC 14 has established several test methods for biodegradation testing of plastic materials
under laboratory conditions covering different environmental compartments and test conditions, as
shown in Table 1.Table 1 — Test methods for biodegradation testing of plastics
Conditions
Test methods
Environmental compartment Presence/absence of oxygen
ISO 14855-1
Controlled composting conditions Aerobic conditions
ISO 14855-2
High-solids anaerobic-digestion
Anaerobic conditions ISO 15985
conditions
Controlled anaerobic slurry system Anaerobic conditions ISO 13975
Soil Aerobic conditions ISO 17556
ISO 14851
Aerobic conditions
Aqueous medium ISO 14852
Anaerobic conditions ISO 14853
ISO 18830
Seawater/sandy sediment interface Aerobic conditions
ISO 19679
Marine sediment Aerobic conditions ISO 22404
ISO 23977-1
Seawater Aerobic conditions
ISO 23977-2
Test method for measuring biodegradation of plastic materials when exposed to marine microbes.
All marine biodegradation test methods are based on exposure of plastic materials to marine samples
(seawater and/or sediment) taken from shoreline areas. By a quantitative viewpoint, these methods
are not equivalent, because, for example, the microbial density in seawater is generally lower compared
to the density determined in sediment. In addition, the microbial composition and diversity can be
different. Moreover, as a rule, the nutrient concentration found in sediment is normally higher compared
to the concentration in seawater.This document provides a test method for determining the biodegradation level of plastic materials
exposed to the microbial population present in seawater from a pelagic zone under laboratory
conditions. The biodegradation is followed by measuring the evolved CO .The test is performed with either seawater only (“pelagic seawater test”) or with seawater to which
little sediment was added (“suspended sediment seawater test”).© ISO 2020 – All rights reserved v
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ISO 23977-1:2020(E)
The pelagic seawater test simulates the conditions found in offshore areas with low water currents and
low tidal movements, whereas the suspended sediment seawater test simulates conditions which might
be found in coastal areas with stronger water currents and tidal movements.vi © ISO 2020 – All rights reserved
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oSIST prEN ISO 23977-1:2021
INTERNATIONAL STANDARD ISO 23977-1:2020(E)
Plastics — Determination of the aerobic biodegradation of
plastic materials exposed to seawater —
Part 1:
Method by analysis of evolved carbon dioxide
1 Scope
This document specifies a laboratory test method for determining the degree and rate of the aerobic
biodegradation level of plastic materials. Biodegradation is determined by measuring the CO evolved
from plastic materials when exposed to seawater sampled from coastal areas under laboratory
conditions.The conditions described in this document might not always correspond to the optimum conditions for
the maximum degree of biodegradation, however this test method is designed to give an indication of
the potential biodegradability of plastic materials.NOTE This document addresses plastic materials but can also be used for other materials.
2 Normative referencesThe 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 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 8245, Water quality — Guidelines for the determination of total organic carbon (TOC) and dissolved
organic carbon (DOC)ISO 10210, Plastics — Methods for the preparation of samples for biodegradation testing of plastic
materialsISO 10523, Water quality — Determination of pH
ISO 11261, Soil quality — Determination of total nitrogen — Modified Kjeldahl method
3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp— IEC Electropedia: available at http:// www .electropedia .org/
3.1
pelagic zone
water body above the seafloor
Note 1 to entry: It is also referred to as the open water or the water column.
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ISO 23977-1:2020(E)
Note 2 to entry: The surface of the pelagic zone is moved by wind-driven waves, is in contact with the atmosphere
and exposed to sunlight. With increasing depth pressure increases, temperature decreases, and light and surface
wave energy are attenuated.[SOURCE: ISO 22766:2020, 3.4]
3.2
dissolved inorganic carbon
DIC
part of the inorganic carbon in water which cannot be removed by specified phase separation
Note 1 to entry: Phase separation can be achieved for example by centrifugation at 40 000 m⋅s for 15 min or by
membrane filtration using membranes with pores of 0,2 μm to 0,45 μm diameter.[SOURCE: ISO 14852:—, 3.4]
3.3
theoretical amount of evolved carbon dioxide
ThCO
maximum theoretical amount of carbon dioxide evolved after completely oxidizing a chemical
compound, calculated from the molecular formulaNote 1 to entry: It is expressed as milligrams of carbon dioxide evolved per milligram or gram of test compound.
[SOURCE: ISO 14852:—, 3.5]3.4
total organic carbon
TOC
amount of carbon bound in an organic compound
Note 1 to entry: It is expressed as milligrams of carbon per 100 mg of the compound.
[SOURCE: ISO 17556:2019, 3.14]3.5
dissolved organic carbon
DOC
part of the organic carbon in water which cannot be removed by specified phase separation
Note 1 to entry: Phase separation can be achieved for example by centrifugation at 40 000 m⋅s for 15 min or by
membrane filtration using membranes with pores of 0,2 μm to 0,45 μm diameter.[SOURCE: ISO 14852:—, 3.7]
3.6
lag phase
time from the start of a test until adaptation and/or selection of the degrading microorganisms is
achieved and the degree of biodegradation of a chemical compound or organic matter has increased to
about 10 % of the maximum level of biodegradation (3.8)Note 1 to entry: It is measured in days.
[SOURCE: ISO 14852:—, 3.8]
3.7
biodegradation phase
time from the end of the lag phase (3.6) of a test until the plateau phase has been reached
Note 1 to entry: It is measured in days.[SOURCE: ISO 14852:—, 3.10]
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3.8
maximum level of biodegradation
degree of biodegradation of a chemical compound or organic matter in a test, above which no further
biodegradation takes place during the testNote 1 to entry: It is measured in per cent.
[SOURCE: ISO 14852:—, 3.9]
3.9
plateau phase
time from the end of the biodegradation phase (3.7) until the end of a test
Note 1 to entry: It is measured in days.
[SOURCE: ISO 14852:—, 3.11]
3.10
pre-conditioning
pre-incubation of an inoculum under the conditions of the subsequent test in the absence of the chemical
compound or organic matter under test, with the aim of improving the test by acclimatization of the
microorganisms to the test conditions[SOURCE: ISO 14852:—, 3.13]
4 Principle
This document describes two variations of a test method for determining the biodegradability of plastic
materials by the indigenous population of microorganisms in natural seawater using a static aqueous
test system. The test is performed under mesophilic test conditions for up to two years by incubating
plastic materials with either seawater only (“pelagic seawater test”) or with seawater to which low
amount of sediment has been added (“suspended sediment seawater test”), coming from the same site
as that from which the seawater was taken.Biodegradation is followed by measuring the evolution of carbon dioxide using a suitable, analytical
method. The level of biodegradation is determined by comparing the amount of carbon dioxide evolved
with the theoretical amount [theoretical amount of evolved carbon dioxide (ThCO )] and expressed in
percentage. The test result is the maximum level of biodegradation, determined from the plateau phase
of the biodegradation curve. The principle of a system for measuring evolved carbon dioxide is given in
ISO 14852:—, Annex A.5 Test environment
Incubation shall take place in the dark or in diffused light, in an enclosure which is free from vapours
inhibitory to marine microorganisms and which is maintained at a constant mesophilic temperature.
It should preferably be between 15 °C to 25 °C, but not exceeding 28 °C, to an accuracy of ±1 °C. Any
change in temperature shall be justified and clearly indicated in the test report.
NOTE Test results are obtained for temperatures that can be different from real conditions in marine
environment.6 Reagents
Use only reagents of recognized analytical grade.
6.1 Water
Distilled or deionized water, free of toxic substances (copper in particular) and containing less than
2 mg/l of TOC.© ISO 2020 – All rights reserved 3
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6.2 Natural seawater/sediment
Sampling, preservation, handling, transport and storage of natural seawater, and, if applicable,
sediment collected from the same site as that from which the seawater is taken, shall be in accordance
with ISO 5667-3.Prior to use, remove coarse particles from the seawater and, if applicable, from the sediment by
appropriate means. The procedure used shall be reported.Seawater can be filtered using a paper filter in order to remove coarse particles. It is recommended to
reduce the amount of coarse particles in sediment by means of at least two washing steps using filtered
seawater without coarse particles.Measure TOC, pH and nitrogen content of seawater and, if applicable, of sediment samples according to
ISO 8245, ISO 10523 and ISO 11261, respectively.If the TOC content of the seawater sample is found to be high, the seawater should be pre-conditioned
for about a week prior to use. If, for instance, the background concentration of TOC exceeds about 20 %
of the total TOC after addition of the test item, then pre-condition the seawater and, if applicable, the
sediment by stirring under aerobic conditions at the test temperature and in the dark or in diffuse light
in order to reduce the content of easily degradable organic material.Provide the following information on the seawater, and, if applicable, on the sediment sample itself:
— date of collection;— depth of collection (m);
— appearance of sample - turbid, clear, etc.;
— temperature at the time of collection (°C);
— salinity (PSU);
— total organic carbon (TOC; mg/l);
— nitrogen (total-N; mg/l);
— pH;
— description of the pre-conditioning process, if applicable.
7 Apparatus
Ensure that all glassware is thoroughly cleaned and, in particular, free from organic or toxic matter.
Required is usual laboratory equipment, plus the following.7.1 Test flasks. Biometric flasks of the volume of about 300 ml are appropriate. The vessels shall be
located in a constant temperature room or in an apparatus fitted with a thermostat (e.g. water-bath).
Reactors with higher or lower volumes can be used, if environmental conditions are not affected.
7.2 Container for the CO absorber, (e.g. glass beaker) to be located in the headspace of a test flask
and filled with 10 ml of Ba(OH) 0,012 5 mol/l or 3 ml of KOH 0,5 mol/l.As an alternative to Ba(OH) and KOH 4 ml of NaOH 1 mol/l can be used as a CO -absorber.
2 2A suitable apparatus is shown in Annex A, Figure A.1.
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7.3 Analytical equipment for determining carbon dioxide, consisting of any suitable apparatus
with sufficient accuracy, such as a CO or dissolved inorganic carbon (DIC) analyser or apparatus for
titrimetric determination after complete absorption in a basic solution, shall be used.
7.4 Analytical balance, which shall have a sensitivity of at least 0,1 mg.7.5 Magnetic stirrer.
7.6 pH meter.
8 Procedure
8.1 Test material
The sample shall be of known mass and contain enough carbon to yield CO that can be adequately
measured by the chosen system. Use a test material concentration of at least 100 mg per litre of seawater.
This mass of the sample should correspond to TOC of about 60 mg/l. The maximum mass of sample per
flask is limited by the oxygen supply in the glass flask. The recommended amount per litre seawater
is 150 mg to 300 mg of test material per litre seawater. Calculate the TOC from the chemical formula
or determine it by means of a suitable analytical technique (e.g. elemental analysis or measurement in
accordance with ISO 8245) and calculate the ThCO .The test material is added to a test flask, either as powder or in the form of a film. If the test material
is used in the form of powder, particles of known, narrow size distribution should be used. A particle-
size distribution with a maximum diameter of 250 µm is recommended. The preparation of powder
shall be performed in accordance with ISO 10210. If the test material is used in the form of a film, it
can be added either as pieces in the range of 0,2 cm × 0,2 cm to 0,5 cm × 0,5 cm or as a single plastic
strip (width: approximately 1,0 cm, length: depending on weight of the polymer and thickness of the
film). It is recommended that the plastic strip is fixed in, for example, a Polytetrafluoroethylene (PTFE)
coated fibre net (size: approximately 4 cm × 9 cm, mesh size: 5 mm × 5 mm). The fibre net is folded
into 2 layers (approximately 2 cm × 9 cm) with the plastic strip test material fixed in between. Then, the
two ends of the fibre net are attached together. The test material fixed between the fibre net is placed
upright on the ground of a bottle base in the form of a cylinder (see Annex A, Figure A.2).
The form and shape of the test material can influence its biodegradability. Similar particle sizes of power
should preferably be used in the test. Similar shapes and thicknesses of the films should preferably be
used if different kinds of plastic materials are to be compared.When powder or pieces of films are used in the test, particles or film pieces can stick on the inner
wall of the testing bottle above the seawater. In such cases, a slight manual shaking of the bottle is
recommended to regain the powder or film pieces back to the seawater sample. If the material is added
as a cylindrical plastic strip fixed between, such as a Polytetrafluoroethylene (PTFE) coated fibre net
(see Annex A, Figure A.2), it is immersed in the seawater most of the time.8.2 Reference materials
Use microcrystalline cellulose or ashless cellulose filters as a reference material . If possible, the TOC,
form, and size should be comparable to that of the test material.1) PTFE Glass Fabric (product no 9002) produced by Fiberflon (https:// www .fiberflon .de/ Products/ PTFE -Coated
-Open -Mesh -Fabrics/ Page -307 -17 .aspx) has been found satisfactory for this purpose and is an example of a suitable
product available commercially. This information is given for the convenience of users of this document and does
not constitute an endorsement by ISO of this product.2) Microcrystalline Cellulose "Avicel" produced by Merck or laboratory filter paper Whatman n° 42 has been found
satisfactory for this purpose and are examples of suitable products available commercially. This information is given
for the convenience of users of this document and does not constitute an endorsement by ISO of these products.
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ISO 23977-1:2020(E)
As a negative control, a non-biodegradable polymer (e.g. polyethylene) in the same form as the test
material can be used.8.3 Test set up
Provide several flasks, so that the test includes at least the following:
a) three flasks for the test material (symbol F );
b) three flasks for the blank (symbol F );
c) three flasks for reference material (symbol F ).
In addition, if biodegradation is expected to take longer than 6 months, it is recommended that a
negative control is included:d) three flasks for negative control (symbol F ).
Two flasks for test material, blank, reference material, and negative control may be used instead of
three for screening purposes.8.4 Pre-conditioning phase
As a rule, use a test flask with a volume of 300 ml.
The test is performed in batch by incubating the test materials with either 90 ml of natural seawater
only (“pelagic seawater test”) or with 90 ml of natural seawater to which sediment of 0,1 g/l to 1,0 g/l
(wet weight) has added (“suspended sediment seawater test”).Add carbon dioxide absorber to the absorber compartments of the test flask, as a rule 10 ml Ba(OH)
0,012 5 mol/l, 3 ml of KOH 0,5 mol/l or 4 ml of NaOH 1,0 mol/l. Place the sealed flasks on a magnetic stirrer
(7.5) in a constant-temperature environment and allow all vessels to reach the desired temperature.
Agitation shall be continuous (e.g. 100 r/min agitation) in order to maintain microorganisms and, if
applicable, sediment in suspension.The abrasion of sediment in coastal areas is a natural phenomenon caused by water currents a
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