CEN/TR 15822:2009

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

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.

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

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.

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.
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.
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

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:
a) Plastics added to soil should convert to CO and biomass sufficiently rapidly to ensure that they do not
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
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.
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 comp
...