SIST-TP CEN/TR 15822:2010
(Main)Plastics - Biodegradable plastics in or on soil - Recovery, disposal and related environmental issues
Plastics - Biodegradable plastics in or on soil - Recovery, disposal and related environmental issues
This Technical Report is intended to summarise the current state of knowledge and experience in the field of biodegradable plastics which are used on soil or end up in soil. It also addresses the links between use, disposal after use, degradation mechanisms and the environment.
Therefore, this document is intended to provide a basis for the development of future standards. Its aim is to clarify the ideas and ensure a level playing field, without hiding possible needs for further research or areas of disagreement among experts.
Kunststoffe - Bioabbaubare Kunststoffe in oder auf Böden - Verwertung, Entsorgung und verwandte Umweltthemen
Der vorliegende Technische Bericht ist dafür vorgesehen, den aktuellen Wissensstand und die Erfahrung im Bereich bioabbaubarer Kunststoffe, die auf Böden verwendet werden oder in diese gelangen, zusammen-zufassen. Weiterhin spricht er die Zusammenhänge zwischen der Verwendung, der Entsorgung nach der Verwendung, den Abbaumechanismen und der Umwelt an.
Daher ist dieses Dokument dafür vorgesehen, eine Grundlage für die Erarbeitung zukünftiger Normen zu schaffen. Das Ziel des Dokuments ist, die Ideen zu verdeutlichen und gleiche Wettbewerbsbedingungen sicherzustellen, ohne dabei eine eventuelle Notwendigkeit in weiterer Forschung oder Unstimmigkeiten zwischen Fachleuten zu verschweigen.
Plastiques - Plastiques biodégradables dans et sur les sols - Valorisation, élimination et problèmes environnementaux associés
Le présent Rapport technique a pour but de faire la synthèse de l’état actuel des connaissances et
expériences dans le domaine des plastiques biodégradables qui sont utilisés sur les sols ou éliminés dans le
sol. Il couvre également les relations existant entre l’utilisation, l’élimination après utilisation, les mécanismes
de dégradation et l’environnement.
Par conséquent, ce document est destiné à servir de base au développement de futures normes. Il a pour but
de clarifier les idées et d’assurer des règles de jeu équitables, sans masquer les besoins possibles de
recherches supplémentaires ou les points de désaccord entre experts.
Polimerni materiali - Biorazgradljivi polimerni materiali v ali na tleh - Predelava, odlaganje in sorodna okoljska vprašanja
To tehnično poročilo povzema trenutno stanje znanja in izkušenj na področju biorazgradljivih polimernih materialov, ki se uporabljajo na tleh ali v tleh končajo. Obravnava tudi povezave med uporabo, odlaganjem po uporabi, mehanizmi razgradnje in okoljem. Dokument torej zagotavlja osnovo za razvoj prihodnjih standardov. Njegov cilj je pojasnjevanje zamisli in zagotavljanje enakih pogojev delovanja, ne da bi pri tem skrival morebitne potrebe za nadaljnje raziskave ali področja nestrinjanj med strokovnjaki.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TP CEN/TR 15822:2010
01-februar-2010
Polimerni materiali - Biorazgradljivi polimerni materiali v ali na tleh - Predelava,
odlaganje in sorodna okoljska vprašanja
Plastics - Biodegradable plastics in or on soil - Recovery, disposal and related
environmental issues
Kunststoffe - Bioabbaubare Kunststoffe in oder auf Böden - Verwertung, Entsorgung und
verwandte Umweltthemen
Plastiques - Plastiques biodégradables dans et sur les sols - Valorisation, élimination et
problèmes environnementaux associés
Ta slovenski standard je istoveten z: CEN/TR 15822:2009
ICS:
13.030.99 Drugi standardi v zvezi z Other standards related to
odpadki wastes
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST-TP CEN/TR 15822:2010 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TP CEN/TR 15822:2010
TECHNICAL REPORT
CEN/TR 15822
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
November 2009
ICS 13.030.99; 83.080.01
English Version
Plastics - Biodegradable plastics in or on soil - Recovery,
disposal and related environmental issues
Plastiques - Plastiques biodégradables dans et sur les sols Kunststoffe - Bioabbaubare Kunststoffe in oder auf Böden -
- Valorisation, élimination et problèmes environnementaux Verwertung, Entsorgung und verwandte Umweltthemen
associés
This Technical Report was approved by CEN on 20 October 2008. It has been drawn up by the Technical Committee CEN/TC 249.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15822:2009: E
worldwide for CEN national Members.
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Contents Page
Foreword .3
Introduction .4
1 Scope .5
2 General background .5
3 Polymer degradation in the environment – a reminder .6
3.1 General .6
3.2 Degradation in outdoor conditions .6
4 Starting point and possible developments .7
5 Assessment of the disintegration in soil of biodegradable plastic items .9
6 Environmental safety – Uncontrolled dissemination of dangerous substances in soils .9
6.1 Hazardous substances .9
6.2 Ecotoxicity testing .9
7 Simulation of field conditions – Effect of environmental factors and appropriate pre-
teatment . 10
7.1 Testing schemes . 10
7.2 Intensity of the pre-treatment . 11
7.3 Proposed way forward . 12
8 Mineralisation – Proposal to characterise mineralisation and standard format for
reporting . 12
9 Conclusions . 13
Bibliography . 14
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Foreword
This document (CEN/TR 15822:2009) has been prepared by Technical Committee CEN/TC 249 “Plastics”, the
secretariat of which is held by NBN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
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Introduction
Biodegradable plastics are a broad class of materials, encompassing various types of very different polymers
and final products, which have been classified in different ways.
CEN/TC 249/WG 9 has previously prepared a Technical Report [1], intended to harmonise the terminology to
be used in the field of degradable and biodegradable polymers and plastic items. It is based on scientific
considerations and on a technical analysis of the various stages and mechanisms involved in the degradation
of plastics; its use should help to avoid misleading claims or statements and to increase the knowledge in the
field.
It should be clear that, as for any other material, the overall environmental impact of using biodegradable
plastics, and the related environmental issues, should be assessed on the basis of their entire life cycle in a
given system, e.g. according to the requirements of EN ISO 14040 series of standards on Life Cycle
Assessments. Furthermore, the communication of the results of such assessments is governed by other ISO
standards (e.g. EN ISO 14020 series on Environmental Labels and Self-claims, ISO 14063 on environmental
communication).
All of these standards aim to harmonise the approaches to environmental issues, and play an important role in
preventing confusion in the mind of target audiences.
In the perspective of sustainability, it is also important to note that the environmental dimension and related
issues are only one of the three dimensions which need to be considered, the others being social and
economic dimensions.
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1 Scope
This Technical Report is intended to summarise the current state of knowledge and experience in the field of
biodegradable plastics which are used on soil or end up in soil. It also addresses the links between use,
disposal after use, degradation mechanisms and the environment.
Therefore, this document is intended to provide a basis for the development of future standards. Its aim is to
clarify the ideas and ensure a level playing field, without hiding possible needs for further research or areas of
disagreement among experts.
2 General background
During the last decade several standardisation activities have been undertaken to characterise the behaviour
of biodegradable polymers when exposed to composting conditions. A group particularly active in Europe was
CEN/TC 261/SC 4/WG 2 (Packaging and environment/Organic recovery). The activity of this group was
restricted to biodegradability and compostability of packaging. Other applications or other biodegradation
environments were not addressed. This was due to the limits of the mandate given to CEN by the European
Commission [2]. The standards to be developed were intended to give presumption of conformity with the
essential requirements of the packaging and packaging waste directive [3] relating to biodegradability and
compostability of packaging claimed to be "recoverable in the form of organic recovery" (i.e. composting and
biogasification).
The resulting European Standard EN 13432 was finalized in 2000. This standard defines the requirements for
composting of packaging; a new European Standard dealing with the evaluation of the compostability of
plastics (EN 14995) has been completed recently.
In other applications of plastics, however, composting is not likely to be the final treatment. Several plastic
materials and products have been designed for applications ending up in or on soil. They have been
developed for applications where biodegradation is beneficial from a technical, environmental, social or
economic standpoint. Examples can be found in agriculture (e.g. mulching film), horticulture (twines and clips,
flower pots, pins, etc.), funeral items (e.g. body bags), recreation (e.g. plastic “clay” pigeons for shooting,
hunting cartridges), etc. In many cases recovery and/or recycling of these plastic items is either difficult or not
economically viable; various types of biodegradable plastics have been developed which have been designed
to biodegrade and disappear in situ after their useful life.
So far, it has not been possible to reach a consensus on a single testing scheme to be applied to
biodegradable plastics for such applications. The issue of "pre-treatment", i.e. exposure of specimens to
light/heat realistically representing the field conditions, before testing the biodegradation in soil, has caused
much discussion between involved parties.
Long-term effects, like the possible persistency and bio-accumulation of the remaining fragments or the
release of harmful degradation species or of additives like heavy metals or metal compounds are also of
concern.
However, there is general agreement that soil cannot be considered as a dumping location for plastic particles,
no matter if they are proven safe, with no adverse effects on terrestrial or aquatic organisms, and if they are
invisible.
Standards which define biodegradable plastics suitable for degradation in soil are important for industry, users
and all stakeholders. It is important, for the development of such standards to refer to the findings of science
and to robust evidence based on field experience as well as to identify the needs for further research and
possible environmental improvement of products. This is a prerequisite for ensuring a “level playing field” for
all biodegradable products. The only standard that currently exists is the French NF U 52-001:2005,
Biodegradable materials for use in agriculture and horticulture — Mulching products — Requirements and test
methods.
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The following is a short summary of the most relevant published scientific evidence concerned with the
degradation of biodegradable plastics in the environment. The discussion is based, at least in part, on many
years of field experience of the use of plastics in agriculture (see bibliography for fuller information).
3 Polymer degradation in the environment – a reminder
3.1 General
The ultimate fate of a biodegradable plastic in the environment depends on the intrinsic properties of the
material, in particular:
a) the chemical structure of the polymer; and
b) the way in which it has been converted to an industrial product and the nature of that product (e.g.
thickness, incorporation of additives, etc.).
It also depends upon external factors, in particular:
c) the conditions to which the material is exposed in the environment before its final disposal or degradation
into final residues; and
d) the final disposal option.
It is worth mentioning that the biodegradability of a plastic is directly related to the chemical structure of the
polymer molecules, and not to the origin of the raw materials (petrochemical or biomass).
3.2 Degradation in outdoor conditions
There are two main routes that can lead from a plastic product to the ultimate stage, mineralisation and
biomass formation, as shown in Figure 1 below (see also CEN/TR 15351 [1]). These are:
Figure 1 — Schematic of routes to biomineralisation
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a) Cell-mediated degradation
The left-hand route corresponds to the attack of cellular enzymes on a polymeric substrate, followed by
biochemical processing of the degradation products as a result of enzymatic reactions. This route requires the
presence of appropriate enzymes and thus of specific cells under viable conditions (atmosphere, water,
nutrients). In nature, enzymes cannot be found without the presence of living cells. In other words there is no
degradation by living systems under conditions which do not support living organisms.
b) Chemically-mediated degradation
The right hand route differs from that of the left side in the sense that the breakdown of the polymer depends
on abiotic chemical processes. Subsequently, only the small molecules generated by chemical degradation
have to be eliminated through biochemical pathways. Here the conditions required to trigger chemical
degradation are necessary (light, water, oxygen, heat, etc.). Without these influences there is no degradation.
On the other hand, living cells have to be present to ensure the biochemical processing of the low molar mass
molecules formed from the original polymer.
The most important abiotic factors are water, oxygen, temperature and sunlight. All may be significant for any
given plastic, though their relative importance depends on the polymer structure and the intended use (e.g.
application in/on soil). For example, plastics containing ester groups are more sensitive to hydrolysis (with or
without the promoting effect of extracellular enzymes) than are polyolefins, but all plastics are affected to
some extent by all three factors.
Sunlight is a source of both UV light and heat. The rate of photochemical reactions is also influenced by the
temperature and an increase of temperature generally causes acceleration, with the degree depending upon
the particular material. The overall effect of this combination of heat and light and humidity is normally referred
to by polymer technologists as “weathering”. The combination of different environmental influences often
produces a greater effect than either would produce alone, an effect known as synergism.
All plastics are affected by the synergistic effects of UV light, heat and water, leading to significant change in
mechanical properties (e.g. elongation at break, Eb). In the case of saturated hydrocarbon polymers (e.g.
polyethylene), this normally results in chain scission, due to peroxidation, followed by fragmentation. In the
case of hydrolytically-degrading polymers, chain scission occurs by hydrolysis, again leading to fragmentation.
However, hydrolytically-degrading polymers also photo-degrade. For example, polyesters, such as poly(lactic
acid) (PLA) initially show molecular enlargement (cross-linking) on exposure to UV, but extended exposure
leads to a rapid decrease in molecular weight.
4 Starting point and possible developments
EN 13432, applicable to packaging waste in the framework of the European directive on packaging and
packaging waste, was developed with the main purposes of
setting up a testing procedure to provide reliable and quantifiable results;
preventing misleading claims of biodegradability under composting conditions;
preventing negative effects of packaging residues on compost quality and their accumulation in or on soil;
whilst targeting two "organic recycling" options for packaging waste treatment as defined in the Directive,
namely industrial composting and biomethanisation (or anaerobic digestion).
The above objectives remain valid for any biodegradable plastic at the end of its life. However, generalisation
to all types of applications (mulching films, body bags, hygiene products, agricultural items, etc.), in all types of
environmental conditions, has to take into account scientific findings and field experience.
The following principles should always govern the development of standards as well as the related
communication on biodegradable plastics:
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a) Plastics added to soil should convert to CO and biomass sufficiently rapidly to ensure that they do not
2
show long-term accumulation in the soil.
b) Neither the plastics themselves nor their degradation products and residues should be toxic to
microorganisms, macroorganisms (e.g. worms), plants or the animals which consume them. Furthermore,
they should neither negatively influence the germination of seeds or the yield of crops, nor have
unacceptable environmental impacts on air, water and soil.
c) The evaluation of biodegradability of plastics, as materials, should be based on conditions as
representative as possible of the actual field conditions (e.g. soil burial). The requirements have to meet
market quality needs and social acceptability criteria.
d) Promotion of, and claims about, biodegradable plastics have to be based on their own benefits. Claims
and labels need to comply with EN ISO 14020, EN ISO 14021, EN ISO 14024 and ISO 14025. Eventual
biodegradability cannot be presented, even implicitly, as an excuse for uncontrolled littering.
e) Any standard should in no case jeopardise existing waste recovery schemes.
There is nevertheless so far no agreement on how to test the end-of-life biodegradability of plastics used e.g.
in agriculture. Should testing be performed on plastic materials or only on fabricated products, with pre-aging
or not? The scientific arguments outlined in the introduction may suggest that, since all polymers change in
the environment then all biodegradation tests must be performed on plastics that have been exposed to the
environment in which they are used or in a testing environment which simulates these conditions well.
During biodegradation in the soil, the organic carbon originally contained in a plastic material present in the
soil will be partly the original undigested material, part will have been converted into CO and part will give rise
2
to “intermediates” (residues, biomass, humus, other biochemical molecules). This process is schematically
illustrated in Figure 2.
Figure 2 — Metabolism of organic carbon
A biodegradable plastic suitable for use in agriculture should eventually be fully converted into inorganic
carbon, closing the carbon cycle loop. Once a plastic material is applied in the soil (no matter if biodegradable
or not) there will be an increase of its concentration in the soil. The balance between input rate (applications)
and output rate (mineralization) will cause, at equilibrium, a certain concentration of this plastic material.
Possible way forward
The biodegradability and environmental safety of a material may be verified with a basic test method,
according to standard specifications and test methods to be developed. The specific biodegradation behaviour,
in a specific location, of a plastic product made with this material will need to be checked with a specific test
approach according to specifications which also have to be developed by the relevant product committees on
the basis of existing science and field experience.
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5 Assessment of the disintegration in soil of biodegradable plastic items
After use, if the plastic product is left in the soil, it is expected firstly to “disappear”, i.e. not to leave any easily
visible fragments. In order to determine the time needed to reach a standardised level of disintegration, i.e. a
substantial disappearance of the plastic product, a standard disintegrability test would be helpful. No such
standards exist at present.
The basic idea is to expose samples in a soil under realistically representative laboratory conditions simulating
the actual end-of-life exposure of the plastic product as well as possible.
It is important to distinguish between the assessment of disintegration of a product after use, in its specific
physical form, from the assessment of its service lifetime (durability) (which is a performance characteristic of
the product). A product is expected to have the desired lifetime (in order to fulfil its service function) and
afterwards, as waste, to disintegrate relatively fast (to solve the problem of waste management). The two
behaviours are different and should be treated with a different approach.
A short service lifetime is needed for some applications, while for others a longer service life is required by the
final user. This characteristic is related to the application and to the user’s needs. Thus durability, although it
may be important in practice, is outside the scope of this report, as it concerns the final product performance.
In contrast, disintegrability is a characteristic which influences the size and the level of plastic fragments that
will, at least temporarily, remain present in the soil, constituting visual pollution and possibly changing the soil
structure.
6 Environmental safety – Uncontrolled dissemination of dangerous substances in
soils
6.1 Hazardous substances
To prevent any negative impact on the quality of the compost produced and on soils amended with such a
compost, EN 13432 defines maximum concentrations for eleven metals possibly present in biodegradable
plastic packaging. Similar regulations or legislation relating to compost quality, hazardous waste or hazardous
substances/preparations exist in Europe and in various countries [4] (e.g. Regulation (EC) No. 1907/2006 of
the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation,
Authorisation and Restriction of Chemicals (REACH)).
Unless proven not to be relevant for the specific case under consideration, biodegradable plastics
decomposing in soils should also comply with these limits and criteria.
Interactions of metals with soil and plants are out of the scope of CEN/TC 249. Other groups involved in plant
physiology, etc. should provide data and requirements about that. CEN/TC 249 can only take in criteria
already defined by regulations and standards which control the introduction of metals in soil (e.g. metals
acceptable in soil improvers, limits applicable to hazardous waste). A similar approach was followed by
CEN/TC 261 SC4 WG2 during the preparation of EN 13432. In that case, the criteria of the Community Eco-
Label to Soil Improvers (EC OJL, 219, 7.8.98, p. 39) were accepted.
In any case, the legislation applicable to soil contamination or to waste has to be complied with strictly.
6.2 Ecotoxicity testing
The aim of ecotoxicity testing is to verify that the addition of plastics to the soil does not cause the build up of
persistent molecules with toxic effects towards living organisms. For this reason, ecotoxicity should be tested
when biodegradation has reached an advanced stage. The provision of this information is as important as
information on product performance, which may include ecotoxicity testing of the original product.
The soil containing any possible residues of biodegraded plastic material should be assessed for ecotoxicity in
comparison with a reference soil, where a reference material has been degraded in parallel (e.g. cellulose).
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The assessment of the toxic activities present in soil after degradation is very informative because any
potentially poorly-degradable toxic molecules will have been produced and accumulated at this point. The
ecotoxic activity assessed in this case is the cumulative sum of all poorly-degradable toxic molecules released
during the different stages. It is, therefore, possible to verify the presence of ecotoxic materials with just one
sampling, irrespective of when they were produced.
In order to increase the sensitivity of ecotoxicity testing, it may be advisable to apply relatively high initial
concentrations of the polymer under study, simulating repeated applications, year after year.
The same ecotoxicological test as specified in EN 13432 should at least be included in any standard on soil
degradation. In this case the test should be performed on the soil in which the test material was degraded.
7 Simulation of field conditions – Effect of environmental factors and appropriate
pre-teatment
7.1 Testing schemes
To assess the biodegradability and disintegration of plastic items of any type at the end of their useful life, any
test scheme (screening test) should take into account the environmental factors to which the material is
exposed during the application phase (solar UV radiation, heat, humidity, etc.). The issue is to agree on
realistic conditions based on existing experience in standardised ageing and weathering simulation tests
gained over the last 40 years. The potential persistence of plastic fragments in the soil and of bio-
accumulation of released substances like metals (or their derivatives) or decomposition species as well as
other potentially harmful emissions into air, water and soil have been addressed in Clauses 4 and 6.
Different products can be made starting from the same base material for different applications. Some will be
exposed to sunlight, some will be only partially exposed and others will not be exposed at all, although only
those buried relatively deeply (e.g. body bags) will see no solar heating effect.
The test material could be tested following one of three possible routes, depending on the application (see
Figure 3).
Figure 3 — Schematic of possible exposure testing
a) Method A. The pre-treatment is a simulation of the simultaneous action of light and heat experienced by
products exposed to sunlight. It is important to define the irradiation parameters (intensity, duration, etc.)
in order to avoid unrealistic over-treatment, also taking into account the geographical area of application.
Such testing should be carried out and reported according to the well developed weathering standard
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methods, (e.g. ISO 4892) using instruments designed to simulate solar radiation, with control of
temperature and humidity.
b) Method B. The pre-treatment is a simulation of the heating caused by sunlight, but without light exposure.
Such testing may again be carried out with or without exposure to water, and might include soil burial
where appropriate; well developed standard methods exist for tests, using air-circulating ovens with
control of temperature and humidity; no such standard is available today for soil burial testing.
c) Method C. No pre-treatment, for those cases or applications in which the plastic is not significantly
exposed to light and/or heat before disposal.
The material after pre-treatment (Method A or B) or untreated (Method C) is then subjected to a
biodegradation test in order to determine its biodegradability and to a disintegration test to determine its
disintegradability.
This scheme does not address the performance of the plastic items (e.g. durability of a mulch film during use
and disintegration after use). It is a simulation test on the material, deemed to represent the actual
biodegradation behaviour of the plastic item at the end of its service life .The results should be confirmed by
similar tests on plastic items after field exposure.
For specific applications it might be necessary to test the same products according to the different test
methods in order to cover all possible environmental conditions.
The proposed testing scheme addresses neither the technical performance of the product nor its commercial
or social acceptability. As an example, “insufficient disintegration” should be dealt with in the disintegrability
test (Clause 5); performance aspects will be dealt with in the relevant performance assessment standards, for
the various conditions prevailing in the field (exposed to sunlight, buried, etc.).
7.2 Intensity of the pre-treatment
It is not realistic to set a fixed time for all types of applications. Even for similar applications, e.g. mulching
films, the spread of requirements and service life is very broad (from very short to much longer life spans,
depending on crop type, or even to very long ones, such as e.g. for tree-protection tubes).
An option may be to classify material
...
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