Plastics — Soil biodegradable materials for mulch films for use in agriculture and horticulture — Requirements and test methods regarding biodegradation, ecotoxicity and control of constituents

This document is applicable to biodegradable plastic materials used to produce mulch films or biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture. This document specifies test methods and evaluation criteria by addressing the following characteristics: a) control of constituents; b) biodegradation; c) negative effects on terrestrial organisms. NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

Plastiques — Matériaux biodégradables dans le sol pour les films de paillage pour utilisation en agriculture et horticulture — Exigences et méthodes d'essai concernant la biodégradation, l'écotoxicité et le contrôle des constituants

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Published
Publication Date
22-Jul-2021
Current Stage
6060 - International Standard published
Start Date
23-Jul-2021
Completion Date
23-Jul-2021
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INTERNATIONAL ISO
STANDARD 23517
First edition
2021-07
Plastics — Soil biodegradable
materials for mulch films for use
in agriculture and horticulture —
Requirements and test methods
regarding biodegradation, ecotoxicity
and control of constituents
Plastiques — Matériaux biodégradables dans le sol pour les films de
paillage pour utilisation en agriculture et horticulture — Exigences
et méthodes d'essai concernant la biodégradation, l'écotoxicité et le
contrôle des constituants
Reference number
ISO 23517:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 23517:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 23517:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Basic requirements ............................................................................................................................................................................................ 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Control of constituents ..................................................................................................................................................................... 3

4.3 Ultimate aerobic biodegradation ............................................................................................................................................ 4

4.4 Negative effects on terrestrial organism........................................................................................................................... 4

5 Detailed requirements ................................................................................................................................................................................... 4

5.1 Control of constituents ..................................................................................................................................................................... 4

5.1.1 Regulated metals and other elements ........................................................................................................... 4

5.1.2 Organic and inorganic fluorine ............................................................................................................................ 4

5.1.3 Other hazardous substances ................................................................................................................................. 4

5.1.4 Volatile solids ...................................................................................................................................................................... 4

5.2 Ultimate aerobic biodegradation ............................................................................................................................................ 5

5.2.1 Test method and evaluation criteria ............................................................................................................... 5

5.2.2 Requirements regarding constituents ........................................................................................................... 5

5.3 Negative effects on terrestrial organism........................................................................................................................... 6

5.3.1 Ecotoxicity testing scheme ...................................................................................................................................... 6

5.3.2 Preparation of soils for ecotoxicity tests ..................................................................................................... 6

5.3.3 Acute toxicity plant growth test .......................................................................................................................... 7

5.3.4 Earthworm test ................................................................................................................................................................. 7

5.3.5 Nitrification inhibition test with soil microorganisms ................................................................... 8

6 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Examples of maximum concentrations of regulated metals and other

elements .....................................................................................................................................................................................................................10

Annex B (normative) Maximum concentrations of organic and inorganic fluorine and other

hazardous substances ..................................................................................................................................................................................11

Annex C (normative) Determination of acute effects of materials on the emergence and

growth of higher plants ..............................................................................................................................................................................13

Annex D (normative) Determination of acute effects of materials on earthworms .........................................15

Annex E (normative) Determination of effects on reproduction of earthworms................................................16

Annex F (normative) Determination of nitrification of soil microorganisms ........................................................17

Annex G (normative) Preparation of soils for ecotoxicity testing .......................................................................................18

Annex H (informative) Visual surface evaluation method of the disintegration in a slide

frame test ..................................................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................24

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 23517:2021(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.

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 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 23517:2021(E)
Introduction

Biodegradable mulch films are used worldwide in agriculture and horticulture for many years. They

enhance growing conditions and contribute to increased yields and improved crop quality by, for

example:
— inhibiting the development of weeds;
— reducing significantly the consumption of water and other resources;
— control of soil temperature;
— reduction in leaching of mineral elements and other fertilizer;
— reduction in soil compaction;
— protecting the crops from soil.

Biodegradable mulch films are not designed to be recovered from soil at the end of the intended service

life. Therefore, it is no longer necessary for farmers to retrieve the biodegradable mulch film from the

field for disposal or recycling after the harvest. Farmers can simply plow it under along with what

remains from the plants so that it is incorporated into soil.

This document defines the standard specification to be met for biodegradable mulch films to be

used in agriculture and horticulture. It is suited to characterize both the plastic materials which are

used to manufacture mulch films and the mulch films itself with respect to characteristics such as

biodegradation, adverse effects on terrestrial organisms and control of constituents.

© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 23517:2021(E)
Plastics — Soil biodegradable materials for mulch films for
use in agriculture and horticulture — Requirements and
test methods regarding biodegradation, ecotoxicity and
control of constituents
1 Scope

This document is applicable to biodegradable plastic materials used to produce mulch films or

biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture.

This document specifies test methods and evaluation criteria by addressing the following

characteristics:
a) control of constituents;
b) biodegradation;
c) negative effects on terrestrial organisms.

NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic

products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

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 amendment s applies.

ISO 10390, Soil quality — Determination of pH

ISO 11268-1, Soil quality — Effects of pollutants on earthworms — Part 1: Determination of acute toxicity

to Eisenia fetida/Eisenia andrei

ISO 11268-2, Soil  quality  —  Effects  of  pollutants  on  earthworms  —  Part  2:  Determination  of  effects  on

reproduction of Eisenia fetida/Eisenia andrei

ISO 11269-2, Soil  quality  —  Determination  of  the  effects  of  pollutants  on  soil  flora  —  Part  2:  Effects  of

contaminated soil on the emergence and early growth of higher plants

ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods

ISO 15685, Soil quality — Determination of  potential nitrification and inhibition of nitrification — Rapid

test by ammonium oxidation

ISO 17556, Plastics — Determination of the ultimate aerobic biodegradability of plastic materials in soil by

measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

EN 14582, Characterization of waste — Halogen and sulfur content — Oxygen combustion in closed

systems and determination methods

OECD. (2006), Test No. 208, Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, OECD

Guidelines for the Testing of Chemicals, Section 2
© ISO 2021 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 23517:2021(E)
3 Terms and definitions
For 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.el ectropedia. org/
3.1
mulch film

film made from thermoplastic material intended to be used in agriculture and horticulture to cover the

ground in order to improve growing conditions of crops and depending on the colour to control weeds

Note 1 to entry: It is assumed that a transparent mulch film does not allow to control weeds.

[SOURCE: EN 17033:2018, 3.1.1]
3.2
material

homogenous preparation of biodegradable polymer and additives, as necessary, such as carbon black

and colour pigments

Note 1 to entry: Additives are usually introduced under the form of masterbatches using as carrier resin a

biodegradable polymer.
[SOURCE: EN 17033:2018, 3.1.2]
3.3
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

[SOURCE: ISO 17088:2021, 3.9]
3.4
mineralization

decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides,

oxides or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]
3.5
disintegration
physical breakdown of a material into fragments
[SOURCE: ISO 18606:2013, 3.3]
3.6
degradation

irreversible process leading to a significant change in the structure of a material, typically characterized

by a change of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by

fragmentation, affected by environmental conditions, proceeding over a period of time and comprising

one or more steps
[SOURCE: ISO 472:2013, 2.262]
2 © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 23517:2021(E)
3.7
total dry solid

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
[SOURCE: ISO 17088:2021, 3.8]
3.8
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids (3.7) of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

[SOURCE: ISO 17088:2021, 3.10]
3.9
organic constituent

chemical constituent that contains carbon covalently linked to other carbon atoms and to other

elements, most commonly hydrogen, oxygen or nitrogen

Note 1 to entry: Inorganic carbonates, carbides, cyanides and simple oxides such as carbon monoxide and carbon

dioxide are not considered as organic constituent.

Note 2 to entry: Allotropes of carbon, such as diamond, graphite, carbon black, fullerenes, and carbon nanotubes

are also not considered as organic constituent.
[SOURCE: ISO 17088:2021, 3.15]
3.10
natural soil
soil collected from the surface layer of fields and/or forests
[SOURCE: EN 17033:2018, 3.3.1]
3.11
poly- and perfluoroalkyl substances
PFAS

organofluorine compounds containing only carbon-fluorine bonds and carbon-carbon bonds but also

other heteroatoms
4 Basic requirements
4.1 General

In order to be identified as a biodegradable mulch film in accordance with this document, the mulch film

or the material of the mulch film under investigation shall fulfil all requirements specified in Clause 4

and Clause 5, respectively.
If not all requirements are met, no reference to this document shall be made.
4.2 Control of constituents

The mulch film or the material of the mulch film shall be identified and characterized prior to testing

including:
— determination of the presence of regulated metals and other elements;

— determination of the presence of organic [poly- and perfluoroalkyl substances (PFAS)] and inorganic

fluorine (determined as fluorine);
© ISO 2021 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 23517:2021(E)

— evaluation of the presence of other hazardous substance as specified in Annex B;

taking legal compliance into consideration.
In addition, volatile solids shall be determined.
4.3 Ultimate aerobic biodegradation

The ultimate level of aerobic biodegradation shall be established by testing under controlled conditions

as laid down in 5.2.1.
4.4 Negative effects on terrestrial organism

The mulch film or the material of the mulch film shall have no adverse effects on terrestrial organisms.

5 Detailed requirements
5.1 Control of constituents
5.1.1 Regulated metals and other elements

The concentrations of regulated metals and other elements in a mulch film or material of the mulch film

shall be less than 50 % of those prescribed for sludges, fertilizers and composts in the country where

the final product will be placed on the market or disposed of (see Annex A for examples).

Regulated metals and other elements shall be determined and reported.
5.1.2 Organic and inorganic fluorine
5.1.2.1 Organic fluorine (PFAS)

From a precautionary perspective, poly- and perfluoroalkyl substances (PFAS) shall not be intentionally

added to the mulch film or to a material of the mulch film.

NOTE Most of poly- and perfluoroalkyl substances (PFAS) are extremely persistent in the environment and

in addition, certain PFAS are suspected to have bioaccumulative properties and adverse effects for environment

and human health.
5.1.2.2 Inorganic fluorine

The concentration of inorganic fluorine in the mulch film or in a material of the mulch film shall be less

than 100 mg fluorine/kg material (dry matter) (see Annex B).
5.1.3 Other hazardous substances

From a precautionary perspective, hazardous substances as specified in Annex B shall not be

intentionally added to a mulch film or material of the mulch film.

Information on the use of hazardous substances shall be recorded and can be based on a self-declaration.

5.1.4 Volatile solids

A mulch film or material of a mulch film shall contain a minimum of 60 % of volatile solids.

Volatile solids shall be determined and reported.
4 © ISO 2021 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 23517:2021(E)
5.2 Ultimate aerobic biodegradation
5.2.1 Test method and evaluation criteria

The ultimate aerobic biodegradability shall be determined for the whole material or for each organic

constituent.

Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or

an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to

ISO 17556.

The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil

if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as

specified hereunder:

a) 90 % of the organic carbon shall have been converted to CO by the end of the test period (relative

to a reference material). Both the reference material and the test item shall be tested for the same

length of time and the results compared at the same point in time;

b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to

carbon dioxide by the end of the test period.

If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then

the biodegradation test can be terminated. However, the test period shall be no longer than 2 years.

The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range

between 20 °C and 28 °C, preferably 25 °C.

Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder

or ashless cellulose filters). If possible, the physical form and size of the reference material should be

comparable to that of the test material.
The validity criteria as stated in ISO 17556 shall be fulfilled.

NOTE Biodegradability is assessed by measuring the mineralization level, i.e. the conversion of the organic

carbon of a product or a material into CO with the consumption of O under aerobic conditions, or into CO

2 2 2

and CH under anaerobic conditions. During biodegradation, part of the organic carbon is also assimilated as

biomass. This biomass yield typically ranges from 10 % to 40 %, depending on the substrate. As a consequence,

the mineralization level rarely reaches 100 % also when the biodegradation is 100 %, because of biomass

formation. Standard test methods for the accurate determination of product´s or material’s carbon assimilated in

biomass during biodegradation are not available yet.
5.2.2 Requirements regarding constituents

Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to

demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass).

For organic constituents which are present in the material at a concentration between 1 % and 15 % (by

dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in

5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to

be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301,

[30] [31]

Methods A to F ; OECD 310 ) are considered as biodegradable in the context of ISO 23517.

As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass),

the level of biodegradation of that organic constituent can be determined using an artificial blend of the

same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial

blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to

be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a

material on the condition that the co-substrate is present as tested in the artificial blend.

© ISO 2021 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 23517:2021(E)

Carbon black which is frequently used in mulch film is an inert solid. Therefore, it is not considered as

an organic constituent and shall not be accounted in the calculation of the degree of biodegradation.

NOTE The objective of testing an artificial blend is to demonstrate that a constituent which does not meet

the biodegradability requirements of ISO 23517 when tested alone, may become biodegradable in combination

with another biodegradable constituents of a material. The concentration of the constituent in the artificial

blend was set at a minimum of 15 % in order to avoid false-positive results, as theoretically a material with, for

example, 10 % of a non or moderately biodegradable constituent may still reach the pass level for biodegradation

specified in 5.2.1.
5.3 Negative effects on terrestrial organism
5.3.1 Ecotoxicity testing scheme

Ecotoxicity tests shall be performed in order to investigate possible adverse effects caused by

degradation products resulting from the degradation of the material of a mulch film in soil at the end of

the intended service life.
The test scheme takes into account:

— all relevant terrestrial organism groups as plants, earthworms (invertebrates) and microorganisms;

— important ecological processes critical due to their role in maintaining soil functions as breakdown

of organic matter, formulation of soil structure and cycling of materials;

— all relevant exposure pathways as soil pore water, soil pore air and soil material.

The link between soil organism groups of major ecological importance covering all significant soil

exposure pathways and suitable test methods for the evaluation of ecotoxicity of the materials of mulch

films and their degradation products is shown in Table 1.
Table 1 — Test scheme for the assessment of ecotoxicity
Organism group Ecological process Soil exposure pathway Test methods
plant growth test according to
plants: mainly soil pore water
primary production OECD 208 or ISO 11269-2 with the
- higher plants (by root uptake)
modifications specified in Annex C
diverse and multiple up-
take routes: acute earthworm test according to
ISO 11268-1 with the modifications
breakdown of organic - soil pore water;
invertebrates:
specified in Annex D or alternative-
matter; formation of
- ingestion of soil ly chronic earthworm toxicity test
- earthworms
soil structure
according to ISO 11268-2 with the
material;
modifications laid down in Annex E
- soil air
nitrification inhibition test with
microorganisms:
soil microorganisms according to
recycling of nutrients mainly soil pore water
ISO 15685 with the modifications
- bacteria
specified in Annex F

Ecotoxic effects on terrestrial organism shall be determined by comparing soils produced with or

without the addition of a test material.
5.3.2 Preparation of soils for ecotoxicity tests

The ecotoxicity of degradation products shall be evaluated according to the test methods specified in

5.3.3, 5.3.4 and 5.3.5 using test soils prepared according to Annex G.
6 © ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 23517:2021(E)

The initial test item concentration in the reactor with test material shall be 1 % dry weight.

NOTE Rationale for an initial test item concentration of 1 %: a 1 % loading is much higher than the expected

application loading of a biodegradable mulch film on soil. For example: a typical mulch film is 1,5 × 10 m thick

-3 −2 -2

and has a density of 1 250 kg m . This means 1,875 × 10 kg m for one application. The soil depth where

a mulch film is typically used or remains after use is presumed to be 0,20 m, in agreement with the normal

2 2

depth of soil tillage. Therefore, 1 m of mulch film covering 1 m of soil surface will typically be mixed with a

volume of soil equal to 0,2 m . This amount of soil weighs approximately 300 kg, considering a soil bulk density

of 1 500 kg m . Therefore, the typical loading of the mulch film in normal use will be approximately 0,006 3 %

(1,875 × 10 kg/300 kg × 100) which is far below the initial test item concentration of 1 % taking into account

also various film thickness and repeated applications.
5.3.3 Acute toxicity plant growth test

The purpose of this test is to determine the possible toxic effects of mulch films incorporated in soil

on the emergence, the early stages of growth and development of terrestrial plants. The basis for the

determination is OECD 208 or, alternatively, ISO 11269-2. The principles of the standard test methods

shall be followed with the modifications given in the Annex C.

The germination rate and the plant biomass of the tested plant species in the soil exposed to the test

material shall be more than 90 % of those from the corresponding blank soil not exposed to the test

material.

If the germination rate and the plant biomass of the tested plant species grown on the soil exposed to

the test material as well as on the soil exposed to the reference material (e.g. microcrystalline-cellulose)

is less than 90 % of those from the corresponding blank soil not exposed to any material, then this

could be considered as an indica
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23517
ISO/TC 61/SC 14
Plastics — Soil biodegradable
Secretariat: DIN
materials for mulch films for use
Voting begins on:
2021­05­03 in agriculture and horticulture —
Requirements and test methods
Voting terminates on:
2021­06­28
regarding biodegradation,
ecotoxicity and control of
constituents
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/FDIS 23517:2021(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 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23517:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 23517:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Basic requirements ............................................................................................................................................................................................ 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Control of constituents ..................................................................................................................................................................... 3

4.3 Ultimate aerobic biodegradation ............................................................................................................................................ 4

4.4 Negative effects on terrestrial organism........................................................................................................................... 4

5 Detailed requirements ................................................................................................................................................................................... 4

5.1 Control of constituents ..................................................................................................................................................................... 4

5.1.1 Regulated metals and other elements ........................................................................................................... 4

5.1.2 Organic and inorganic fluorine ............................................................................................................................ 4

5.1.3 Other hazardous substances ................................................................................................................................. 4

5.1.4 Volatile solids ...................................................................................................................................................................... 4

5.2 Ultimate aerobic biodegradation ............................................................................................................................................ 5

5.2.1 Test method and evaluation criteria ............................................................................................................... 5

5.2.2 Requirements regarding constituents ........................................................................................................... 5

5.3 Negative effects on terrestrial organism........................................................................................................................... 6

5.3.1 Ecotoxicity testing scheme ...................................................................................................................................... 6

5.3.2 Preparation of soils for ecotoxicity tests ..................................................................................................... 6

5.3.3 Acute toxicity plant growth test .......................................................................................................................... 7

5.3.4 Earthworm test ................................................................................................................................................................. 7

5.3.5 Nitrification inhibition test with soil microorganisms ................................................................... 8

6 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Examples of maximum concentrations of regulated metals and other

elements .....................................................................................................................................................................................................................10

Annex B (normative) Maximum concentrations of organic and inorganic fluorine and other

hazardous substances ..................................................................................................................................................................................11

Annex C (normative) Determination of acute effects of materials on the emergence and

growth of higher plants ..............................................................................................................................................................................13

Annex D (normative) Determination of acute effects of materials on earthworms .........................................15

Annex E (normative) Determination of effects on reproduction of earthworms................................................16

Annex F (normative) Determination of nitrification of soil microorganisms ........................................................17

Annex G (normative) Preparation of soils for ecotoxicity testing .......................................................................................18

Annex H (informative) Visual surface evaluation method of the disintegration in a slide

frame test ..................................................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................24

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23517:2021(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 61, Plastics, Subcommittee SC 14,

Environmental aspects.

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 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23517:2021(E)
Introduction

Biodegradable mulch films are used worldwide in agriculture and horticulture for many years. They

enhance growing conditions and contribute to increased yields and improved crop quality by, for

example:
— inhibiting the development of weeds;
— reducing significantly the consumption of water and other resources;
— control of soil temperature;
— reduction in leaching of mineral elements and other fertilizer;
— reduction in soil compaction;
— protecting the crops from soil.

Biodegradable mulch films are not designed to be recovered from soil at the end of the intended service

life. Therefore, it is no longer necessary for farmers to retrieve the biodegradable mulch film from the

field for disposal or recycling after the harvest. Farmers can simply plow it under along with what

remains from the plants so that it is incorporated into soil.

This document defines the standard specification to be met for biodegradable mulch films to be

used in agriculture and horticulture. It is suited to characterize both the plastic materials which are

used to manufacture mulch films and the mulch films itself with respect to characteristics such as

biodegradation, adverse effects on terrestrial organisms and control of constituents.

© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23517:2021(E)
Plastics — Soil biodegradable materials for mulch films for
use in agriculture and horticulture — Requirements and
test methods regarding biodegradation, ecotoxicity and
control of constituents
1 Scope

This document is applicable to biodegradable plastic materials used to produce mulch films or

biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture.

This document specifies test methods and evaluation criteria by addressing the following

characteristics:
a) control of constituents;
b) biodegradation;
c) negative effects on terrestrial organisms.

NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic

products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

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 10390, Soil quality — Determination of pH

ISO 11268­1, Soil quality — Effects of pollutants on earthworms — Part 1: Determination of acute toxicity

to Eisenia fetida/Eisenia andrei

ISO 11268­2, Soil quality — Effects of pollutants on earthworms — Part 2: Determination of effects on

reproduction of Eisenia fetida/Eisenia andrei

ISO 11269­2, Soil quality — Determination of the effects of pollutants on soil flora — Part 2: Effects of

contaminated soil on the emergence and early growth of higher plants

ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods

EN 14582, Characterization of waste — Halogen and sulfur content — Oxygen combustion in closed

systems and determination methods

ISO 15685, Soil quality — Determination of potential nitrification and inhibition of nitrification — Rapid

test by ammonium oxidation

ISO 17556, Plastics — Determination of the ultimate aerobic biodegradability of plastic materials in soil by

measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

OECD. (2006), Test No. 208: Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, OECD

Guidelines for the Testing of Chemicals, Section 2
© ISO 2021 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/FDIS 23517:2021(E)
3 Terms and definitions
For 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.el ectropedia. org/
3.1
mulch film

film made from thermoplastic material intended to be used in agriculture and horticulture to cover the

ground in order to improve growing conditions of crops and depending on the colour to control weeds

Note 1 to entry: It is assumed that a transparent mulch film does not allow to control weeds.

[SOURCE: EN 17033:2018, 3.1.1]
3.2
material

homogenous preparation of biodegradable polymer and additives, as necessary, such as carbon black

and colour pigments

Note 1 to entry: Additives are usually introduced under the form of masterbatches using as carrier resin a

biodegradable polymer.
[SOURCE: EN 17033:2018, 3.1.2]
3.3
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

[SOURCE: ISO 17088:2021, 3.9]
3.4
mineralization

decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides,

oxides or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]
3.5
disintegration
physical breakdown of a material into fragments
[SOURCE: ISO 18606:2013, 3.3]
3.6
degradation

irreversible process leading to a significant change in the structure of a material, typically characterized

by a change of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by

fragmentation, affected by environmental conditions, proceeding over a period of time and comprising

one or more steps
[SOURCE: ISO 472:2013, 2.262]
2 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
3.7
total dry solid

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
[SOURCE: ISO 17088:2021, 3.8]
3.8
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids (3.7) of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

[SOURCE: ISO 17088:2021, 3.10]
3.9
organic constituent

chemical constituent that contains carbon covalently linked to other carbon atoms and to other

elements, most commonly hydrogen, oxygen or nitrogen

Note 1 to entry: Inorganic carbonates, carbides, cyanides and simple oxides such as carbon monoxide and carbon

dioxide are not considered as organic constituent.

Note 2 to entry: Allotropes of carbon, such as diamond, graphite, carbon black, fullerenes, and carbon nanotubes

are also not considered as organic constituent.
[SOURCE: ISO 17088:2021, 3.15]
3.10
natural soil
soil collected from the surface layer of fields and/or forests
[SOURCE: EN 17033:2018, 3.3.1]
3.11
poly- and perfluoroalkyl substances
PFAS

organofluorine compounds containing only carbon-fluorine bonds and carbon-carbon bonds but also

other heteroatoms
4 Basic requirements
4.1 General

In order to be identified as a biodegradable mulch film in accordance with this document, the mulch film

or the material of the mulch film under investigation shall fulfil all requirements specified in Clause 4

and Clause 5, respectively.
If not all requirements are met, no reference to this document shall be made.
4.2 Control of constituents

The mulch film or the material of the mulch film shall be identified and characterized prior to testing

including:
— determination of the presence of regulated metals and other elements;

— determination of the presence of organic [poly- and perfluoroalkyl substances (PFAS)] and inorganic

fluorine (determined as fluorine);
© ISO 2021 – All rights reserved 3
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ISO/FDIS 23517:2021(E)

— evaluation of the presence of other hazardous substance as specified in Annex B;

taking legal compliance into consideration.
In addition, volatile solids shall be determined.
4.3 Ultimate aerobic biodegradation

The ultimate level of aerobic biodegradation shall be established by testing under controlled conditions

as laid down in 5.2.1.
4.4 Negative effects on terrestrial organism

The mulch film or the material of the mulch film shall have no adverse effects on terrestrial organisms.

5 Detailed requirements
5.1 Control of constituents
5.1.1 Regulated metals and other elements

The concentrations of regulated metals and other elements in a mulch film or material of the mulch film

shall be less than 50 % of those prescribed for sludges, fertilizers and composts in the country where

the final product will be placed on the market or disposed of (see Annex A for examples).

Regulated metals and other elements shall be determined and reported.
5.1.2 Organic and inorganic fluorine
5.1.2.1 Organic fluorine (PFAS)

From a precautionary perspective, poly- and perfluoroalkyl substances (PFAS) shall not be intentionally

added to the mulch film or to a material of the mulch film.

NOTE Most of poly- and perfluoroalkyl substances (PFAS) are extremely persistent in the environment and

in addition, certain PFAS are suspected to have bioaccumulative properties and adverse effects for environment

and human health.
5.1.2.2 Inorganic fluorine

The concentration of inorganic fluorine in the mulch film or in a material of the mulch film shall be less

than 100 mg fluorine/kg material (dry matter) (see Annex B).
5.1.3 Other hazardous substances

From a precautionary perspective, hazardous substances as specified in Annex B shall not be

intentionally added to a mulch film or material of the mulch film.

Information on the use of hazardous substances shall be recorded and can be based on a self­declaration.

5.1.4 Volatile solids

A mulch film or material of a mulch film shall contain a minimum of 60 % of volatile solids.

Volatile solids shall be determined and reported.
4 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
5.2 Ultimate aerobic biodegradation
5.2.1 Test method and evaluation criteria

The ultimate aerobic biodegradability shall be determined for the whole material or for each organic

constituent.

Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or

an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to

ISO 17556.

The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil

if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as

specified hereunder:

a) 90 % of the organic carbon shall have been converted to CO by the end of the test period (relative

to a reference material). Both the reference material and the test item shall be tested for the same

length of time and the results compared at the same point in time;

b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to

carbon dioxide by the end of the test period.

If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then

the biodegradation test can be terminated. However, the test period shall be no longer than 2 years.

The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range

between 20 °C and 28 °C, preferably 25 °C.

Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder

or ashless cellulose filters). If possible, the physical form and size of the reference material should be

comparable to that of the test material.
The validity criteria as stated in ISO 17556 shall be fulfilled.

NOTE Biodegradability is assessed by measuring the mineralization level, i.e. the conversion of the organic

carbon of a product or a material into CO with the consumption of O under aerobic conditions, or into CO

2 2 2

and CH under anaerobic conditions. During biodegradation, part of the organic carbon is also assimilated as

biomass. This biomass yield typically ranges from 10 % to 40 %, depending on the substrate. As a consequence,

the mineralization level rarely reaches 100 % also when the biodegradation is 100 %, because of biomass

formation. Standard test methods for the accurate determination of product´s or material’s carbon assimilated in

biomass during biodegradation are not available yet.
5.2.2 Requirements regarding constituents

Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to

demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass).

For organic constituents which are present in the material at a concentration between 1 % and 15 % (by

dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in

5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to

be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301,

[30] [31]

Methods A to F ; OECD 310 ) are considered as biodegradable in the context of ISO 23517.

As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass),

the level of biodegradation of that organic constituent can be determined using an artificial blend of the

same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial

blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to

be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a

material on the condition that the co-substrate is present as tested in the artificial blend.

© ISO 2021 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/FDIS 23517:2021(E)

Carbon black which is frequently used in mulch film is an inert solid. Therefore, it is not considered as

an organic constituent and shall not be accounted in the calculation of the degree of biodegradation.

NOTE The objective of testing an artificial blend is to demonstrate that a constituent which does not meet

the biodegradability requirements of ISO 23517 when tested alone, may become biodegradable in combination

with another biodegradable constituents of a material. The concentration of the constituent in the artificial

blend was set at a minimum of 15 % in order to avoid false-positive results, as theoretically a material with, for

example, 10 % of a non or moderately biodegradable constituent may still reach the pass level for biodegradation

specified in 5.2.1.
5.3 Negative effects on terrestrial organism
5.3.1 Ecotoxicity testing scheme

Ecotoxicity tests shall be performed in order to investigate possible adverse effects caused by

degradation products resulting from the degradation of the material of a mulch film in soil at the end of

the intended service life.
The test scheme takes into account:

— all relevant terrestrial organism groups as plants, earthworms (invertebrates) and microorganisms;

— important ecological processes critical due to their role in maintaining soil functions as breakdown

of organic matter, formulation of soil structure and cycling of materials;

— all relevant exposure pathways as soil pore water, soil pore air and soil material.

The link between soil organism groups of major ecological importance covering all significant soil

exposure pathways and suitable test methods for the evaluation of ecotoxicity of the materials of mulch

films and their degradation products is shown in Table 1.
Table 1 — Test scheme for the assessment of ecotoxicity
Organism group Ecological process Soil exposure pathway Test methods
plant growth test according to
plants: mainly soil pore water
primary production OECD 208 or ISO 11269­2 with the
­ higher plants (by root uptake)
modifications specified in Annex C
diverse and multiple up­
take routes: acute earthworm test according to
ISO 11268-1 with the modifications
breakdown of organic ­ soil pore water;
invertebrates:
specified in Annex D or alternative­
matter; formation of
­ ingestion of soil ly chronic earthworm toxicity test
­ earthworms
soil structure
according to ISO 11268­2 with the
material;
modifications laid down in Annex E
­ soil air
nitrification inhibition test with
microorganisms:
soil microorganisms according to
recycling of nutrients mainly soil pore water
ISO 15685 with the modifications
­ bacteria
specified in Annex F

Ecotoxic effects on terrestrial organism shall be determined by comparing soils produced with or

without the addition of a test material.
5.3.2 Preparation of soils for ecotoxicity tests

The ecotoxicity of degradation products shall be evaluated according to the test methods specified in

5.3.3, 5.3.4 and 5.3.5 using test soils prepared according to Annex G.
6 © ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/FDIS 23517:2021(E)

The initial test item concentration in the reactor with test material shall be 1 % dry weight.

NOTE Rationale for an initial test item concentration of 1 %: a 1 % loading is much higher than the expected

application loading of a biodegradable mulch film on soil. For example: a typical mulch film is 1,5 × 10 m thick

­3 −2 ­2

and has a density of 1 250 kg m . This means 1,875 × 10 kg m for one application. The soil depth where

a mulch film is typically used or remains after use is presumed to be 0,20 m, in agreement with the normal

2 2

depth of soil tillage. Therefore, 1 m of mulch film covering 1 m of soil surface will typically be mixed with a

volume of soil equal to 0,2 m . This amount of soil weighs approximately 300 kg, considering a soil bulk density

of 1 500 kg m . Therefore, the typical loading of the mulch film in normal use will be approximately 0,006 3 %

(1,875 × 10 kg/300 kg × 100) which is far below the initial test item concentration of 1 % taking into account

also various film thickness and repeated applications.
5.3.3 Acute toxicity plant growth test

The purpose of this test is to determine the possible toxic effects of mulch films incorporated in soil

on the emergence, the early stages of growth and development of terrestrial plants. The basis for the

determination is OECD 208 or, alternatively, ISO 11269-2. The principles of the standard test methods

shall be followed with the modifications given in the Annex C.

The germination rate and the plant biomass of the tested plant species in the soil exposed to the test

material shall be more than 90 % of those from the corresponding blank soil not exposed to the te

...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23517
ISO/TC 61/SC 14
Plastics — Biodegradable mulch films
Secretariat: DIN
for use in agriculture and horticulture
Voting begins on:
2021­05­03 — Requirements and test methods
regarding biodegradation, ecotoxicity
Voting terminates on:
2021­06­28
and control of constituents
Plastiques — Films de paillage biodégradables pour utilisation
en agriculture et horticulture — Exigences et méthodes d'essai
concernant la biodégradation, l'écotoxicité et le contrôle des
constituants
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/FDIS 23517:2021(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 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23517:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 23517:2021(E)
Contents Page

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

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

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

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

3  Terms and definitions ..................................................................................................................................................................................... 2

4 Basic requirements ............................................................................................................................................................................................ 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Control of constituents ..................................................................................................................................................................... 3

4.3 Ultimate aerobic biodegradation ............................................................................................................................................ 4

4.4 Negative effects on terrestrial organism........................................................................................................................... 4

5 Detailed requirements ................................................................................................................................................................................... 4

5.1 Control of constituents ..................................................................................................................................................................... 4

5.1.1 Regulated metals and other elements ........................................................................................................... 4

5.1.2 Organic and inorganic fluorine ............................................................................................................................ 4

5.1.3 Other hazardous substances ................................................................................................................................. 4

5.1.4 Volatile solids ...................................................................................................................................................................... 4

5.2 Ultimate aerobic biodegradation ............................................................................................................................................ 5

5.2.1 Test method and evaluation criteria ............................................................................................................... 5

5.2.2 Requirements regarding constituents ........................................................................................................... 5

5.3 Negative effects on terrestrial organism........................................................................................................................... 6

5.3.1 Ecotoxicity testing scheme ...................................................................................................................................... 6

5.3.2 Preparation of soils for ecotoxicity tests ..................................................................................................... 6

5.3.3 Acute toxicity plant growth test .......................................................................................................................... 7

5.3.4 Earthworm test ................................................................................................................................................................. 7

5.3.5 Nitrification inhibition test with soil microorganisms ................................................................... 8

6 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Examples of maximum concentrations of regulated metals and other

elements .....................................................................................................................................................................................................................10

Annex B (normative) Maximum concentrations of organic and inorganic fluorine and other

hazardous substances ..................................................................................................................................................................................11

Annex C (normative) Determination of acute effects of materials on the emergence and

growth of higher plants ..............................................................................................................................................................................13

Annex D (normative) Determination of acute effects of materials on earthworms .........................................15

Annex E (normative) Determination of effects on reproduction of earthworms................................................16

Annex F (normative) Determination of nitrification of soil microorganisms ........................................................17

Annex G (normative) Preparation of soils for ecotoxicity testing .......................................................................................18

Annex H (informative) Visual surface evaluation method of the disintegration in a slide

frame test ..................................................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................24

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23517:2021(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 61, Plastics, Subcommittee SC 14,

Environmental aspects.

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 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23517:2021(E)
Introduction

Biodegradable mulch films are used worldwide in agriculture and horticulture for many years. They

enhance growing conditions and contribute to increased yields and improved crop quality by, for

example:
— inhibiting the development of weeds;
— reducing significantly the consumption of water and other resources;
— control of soil temperature;
— reduction in leaching of mineral elements and other fertilizer;
— reduction in soil compaction;
— protecting the crops from soil.

Biodegradable mulch films are not designed to be recovered from soil at the end of the intended service

life. Therefore, it is no longer necessary for farmers to retrieve the biodegradable mulch film from the

field for disposal or recycling after the harvest. Farmers can simply plow it under along with what

remains from the plants so that it is incorporated into soil.

This document defines the standard specification to be met for biodegradable mulch films to be

used in agriculture and horticulture. It is suited to characterize both the plastic materials which are

used to manufacture mulch films and the mulch films itself with respect to characteristics such as

biodegradation, adverse effects on terrestrial organisms and control of constituents.

© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23517:2021(E)
Plastics — Biodegradable mulch films for use in
agriculture and horticulture — Requirements and test
methods regarding biodegradation, ecotoxicity and control
of constituents
1 Scope

This document is applicable to biodegradable plastic materials used to produce mulch films or

biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture.

This document specifies test methods and evaluation criteria by addressing the following

characteristics:
a) control of constituents;
b) biodegradation;
c) negative effects on terrestrial organisms.

NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic

products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

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 10390, Soil quality — Determination of pH

ISO 11268­1, Soil quality — Effects of pollutants on earthworms — Part 1: Determination of acute toxicity

to Eisenia fetida/Eisenia andrei

ISO 11268­2, Soil quality — Effects of pollutants on earthworms — Part 2: Determination of effects on

reproduction of Eisenia fetida/Eisenia andrei

ISO 11269­2, Soil quality — Determination of the effects of pollutants on soil flora — Part 2: Effects of

contaminated soil on the emergence and early growth of higher plants

ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods

EN 14582, Characterization of waste — Halogen and sulfur content — Oxygen combustion in closed

systems and determination methods

ISO 15685, Soil quality — Determination of potential nitrification and inhibition of nitrification — Rapid

test by ammonium oxidation

ISO 17556, Plastics — Determination of the ultimate aerobic biodegradability of plastic materials in soil by

measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

OECD. (2006), Test No. 208: Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, OECD

Guidelines for the Testing of Chemicals, Section 2
© ISO 2021 – All rights reserved 1
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ISO/FDIS 23517:2021(E)
3  Terms and definitions
For 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
mulch film

film made from thermoplastic material intended to be used in agriculture and horticulture to cover the

ground in order to improve growing conditions of crops and depending on the colour to control weeds

Note 1 to entry: It is assumed that a transparent mulch film does not allow to control weeds.

[SOURCE: EN 17033:2018, 3.1.1]
3.2
material

homogenous preparation of biodegradable polymer and additives, as necessary, such as carbon black

and colour pigments

Note 1 to entry: Additives are usually introduced under the form of masterbatches using as carrier resin a

biodegradable polymer.
[SOURCE: EN 17033:2018, 3.1.2]
3.3
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

[SOURCE: ISO 17088:2021, 3.9]
3.4
mineralization

decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides,

oxides or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]
3.5
disintegration
physical breakdown of a material into fragments
[SOURCE: ISO 18606:2013, 3.3]
3.6
degradation

irreversible process leading to a significant change in the structure of a material, typically characterized

by a change of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by

fragmentation, affected by environmental conditions, proceeding over a period of time and comprising

one or more steps
[SOURCE: ISO 472:2013, 2.262]
2 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
3.7
total dry solid

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
[SOURCE: ISO 17088:2021, 3.8]
3.8
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids (3.7) of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

[SOURCE: ISO 17088:2021, 3.10]
3.9
organic constituent

chemical constituent that contains carbon covalently linked to other carbon atoms and to other

elements, most commonly hydrogen, oxygen or nitrogen

Note 1 to entry: Inorganic carbonates, carbides, cyanides and simple oxides such as carbon monoxide and carbon

dioxide are not considered as organic constituent.

Note 2 to entry: Allotropes of carbon, such as diamond, graphite, carbon black, fullerenes, and carbon nanotubes

are also not considered as organic constituent.
[SOURCE: ISO 17088:2021, 3.15]
3.10
natural soil
soil collected from the surface layer of fields and/or forests
[SOURCE: EN 17033:2018, 3.3.1]
3.11
poly- and perfluoroalkyl substances
PFAS

organofluorine compounds containing only carbon-fluorine bonds and carbon-carbon bonds but also

other heteroatoms
4 Basic requirements
4.1 General

In order to be identified as a biodegradable mulch film in accordance with this document, the mulch film

or the material of the mulch film under investigation shall fulfil all requirements specified in Clause 4

and Clause 5, respectively.
If not all requirements are met, no reference to this document shall be made.
4.2 Control of constituents

The mulch film or the material of the mulch film shall be identified and characterized prior to testing

including:
— determination of the presence of regulated metals and other elements;

— determination of the presence of organic [poly- and perfluoroalkyl substances (PFAS)] and inorganic

fluorine (determined as fluorine);
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ISO/FDIS 23517:2021(E)

— evaluation of the presence of other hazardous substance as specified in Annex B;

taking legal compliance into consideration.
In addition, volatile solids shall be determined.
4.3 Ultimate aerobic biodegradation

The ultimate level of aerobic biodegradation shall be established by testing under controlled conditions

as laid down in 5.2.1.
4.4 Negative effects on terrestrial organism

The mulch film or the material of the mulch film shall have no adverse effects on terrestrial organisms.

5 Detailed requirements
5.1 Control of constituents
5.1.1 Regulated metals and other elements

The concentrations of regulated metals and other elements in a mulch film or material of the mulch film

shall be less than 50 % of those prescribed for sludges, fertilizers and composts in the country where

the final product will be placed on the market or disposed of (see Annex A for examples).

Regulated metals and other elements shall be determined and reported.
5.1.2  Organic and inorganic fluorine
5.1.2.1  Organic fluorine (PFAS)

From a precautionary perspective, poly- and perfluoroalkyl substances (PFAS) shall not be intentionally

added to the mulch film or to a material of the mulch film.

NOTE Most of poly- and perfluoroalkyl substances (PFAS) are extremely persistent in the environment and

in addition, certain PFAS are suspected to have bioaccumulative properties and adverse effects for environment

and human health.
5.1.2.2  Inorganic fluorine

The concentration of inorganic fluorine in the mulch film or in a material of the mulch film shall be less

than 100 mg fluorine/kg material (dry matter) (see Annex B).
5.1.3 Other hazardous substances

From a precautionary perspective, hazardous substances as specified in Annex B shall not be

intentionally added to a mulch film or material of the mulch film.

Information on the use of hazardous substances shall be recorded and can be based on a self­declaration.

5.1.4 Volatile solids

A mulch film or material of a mulch film shall contain a minimum of 60 % of volatile solids.

Volatile solids shall be determined and reported.
4 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
5.2 Ultimate aerobic biodegradation
5.2.1 Test method and evaluation criteria

The ultimate aerobic biodegradability shall be determined for the whole material or for each organic

constituent.

Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or

an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to

ISO 17556.

The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil

if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as

specified hereunder:

a) 90 % of the organic carbon shall have been converted to CO by the end of the test period (relative

to a reference material). Both the reference material and the test item shall be tested for the same

length of time and the results compared at the same point in time;

b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to

carbon dioxide by the end of the test period.

If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then

the biodegradation test can be terminated. However, the test period shall be no longer than 2 years.

The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range

between 20 °C and 28 °C, preferably 25 °C.

Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder

or ashless cellulose filters). If possible, the physical form and size of the reference material should be

comparable to that of the test material.
The validity criteria as stated in ISO 17556 shall be fulfilled.

NOTE Biodegradability is assessed by measuring the mineralization level, i.e. the conversion of the organic

carbon of a product or a material into CO with the consumption of O under aerobic conditions, or into CO

2 2 2

and CH under anaerobic conditions. During biodegradation, part of the organic carbon is also assimilated as

biomass. This biomass yield typically ranges from 10 % to 40 %, depending on the substrate. As a consequence,

the mineralization level rarely reaches 100 % also when the biodegradation is 100 %, because of biomass

formation. Standard test methods for the accurate determination of product´s or material’s carbon assimilated in

biomass during biodegradation are not available yet.
5.2.2 Requirements regarding constituents

Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to

demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass).

For organic constituents which are present in the material at a concentration between 1 % and 15 % (by

dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in

5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to

be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301,

[30] [31]

Methods A to F ; OECD 310 ) are considered as biodegradable in the context of ISO 23517.

As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass),

the level of biodegradation of that organic constituent can be determined using an artificial blend of the

same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial

blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to

be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a

material on the condition that the co-substrate is present as tested in the artificial blend.

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ISO/FDIS 23517:2021(E)

Carbon black which is frequently used in mulch film is an inert solid. Therefore, it is not considered as

an organic constituent and shall not be accounted in the calculation of the degree of biodegradation.

NOTE The objective of testing an artificial blend is to demonstrate that a constituent which does not meet

the biodegradability requirements of ISO 23517 when tested alone, may become biodegradable in combination

with another biodegradable constituents of a material. The concentration of the constituent in the artificial

blend was set at a minimum of 15 % in order to avoid false-positive results, as theoretically a material with, for

example, 10 % of a non or moderately biodegradable constituent may still reach the pass level for biodegradation

specified in 5.2.1.
5.3 Negative effects on terrestrial organism
5.3.1 Ecotoxicity testing scheme

Ecotoxicity tests shall be performed in order to investigate possible adverse effects caused by

degradation products resulting from the degradation of the material of a mulch film in soil at the end of

the intended service life.
The test scheme takes into account:

— all relevant terrestrial organism groups as plants, earthworms (invertebrates) and microorganisms;

— important ecological processes critical due to their role in maintaining soil functions as breakdown

of organic matter, formulation of soil structure and cycling of materials;

— all relevant exposure pathways as soil pore water, soil pore air and soil material.

The link between soil organism groups of major ecological importance covering all significant soil

exposure pathways and suitable test methods for the evaluation of ecotoxicity of the materials of mulch

films and their degradation products is shown in Table 1.
Table 1 — Test scheme for the assessment of ecotoxicity
Organism group Ecological process Soil exposure pathway Test methods
plant growth test according to
plants: mainly soil pore water
primary production OECD 208 or ISO 11269­2 with the
­ higher plants (by root uptake)
modifications specified in Annex C
diverse and multiple up­
take routes: acute earthworm test according to
ISO 11268-1 with the modifications
breakdown of organic ­ soil pore water;
invertebrates:
specified in Annex D or alternative­
matter; formation of
­ ingestion of soil ly chronic earthworm toxicity test
­ earthworms
soil structure
according to ISO 11268­2 with the
material;
modifications laid down in Annex E
­ soil air
nitrification inhibition test with
microorganisms:
soil microorganisms according to
recycling of nutrients mainly soil pore water
ISO 15685 with the modifications
­ bacteria
specified in Annex F

Ecotoxic effects on terrestrial organism shall be determined by comparing soils produced with or

without the addition of a test material.
5.3.2 Preparation of soils for ecotoxicity tests

The ecotoxicity of degradation products shall be evaluated according to the test methods specified in

5.3.3, 5.3.4 and 5.3.5 using test soils prepared according to Annex G.
6 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)

The initial test item concentration in the reactor with test material shall be 1 % dry weight.

NOTE Rationale for an initial test item concentration of 1 %: a 1 % loading is much higher than the expected

application loading of a biodegradable mulch film on soil. For example: a typical mulch film is 1,5 × 10 m thick

­3 −2 ­2

and has a density of 1 250 kg m . This means 1,875 × 10 kg m for one application. The soil depth where

a mulch film is typically used or remains after use is presumed to be 0,20 m, in agreement with the normal

2 2

depth of soil tillage. Therefore, 1 m of mulch film covering 1 m of soil surface will typically be mixed with a

volume of soil equal to 0,2 m . This amount of soil weighs approximately 300 kg, considering a soil bulk density

of 1 500 kg m . Therefore, the typical loading of the mulch film in normal use will be approximately 0,006 3 %

(1,875 × 10 kg/300 kg × 100) which is far below the initial test item concentration of 1 % taking into account

also various film thickness and repeated applications.
5.3.3 Acute toxicity plant growth test

The purpose of this test is to determine the possible toxic effects of mulch films incorporated in soil

on the emergence, the early stages of growth and development of terrestrial plants. The basis for the

determination is OECD 208 or, alternatively, ISO 11269-2. The principles of the standard test methods

shall be followed with the modifications given in the Annex C.
The germination rate and the
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23517
ISO/TC 61/SC 14
Plastics — Soil biodegradable
Secretariat: DIN
materials for mulch films for use
Voting begins on:
2021­05­03 in agriculture and horticulture —
Requirements and test methods
Voting terminates on:
2021­06­28
regarding biodegradation,
ecotoxicity and control of
constituents
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/FDIS 23517:2021(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 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23517:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Basic requirements ............................................................................................................................................................................................ 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Control of constituents ..................................................................................................................................................................... 3

4.3 Ultimate aerobic biodegradation ............................................................................................................................................ 4

4.4 Negative effects on terrestrial organism........................................................................................................................... 4

5 Detailed requirements ................................................................................................................................................................................... 4

5.1 Control of constituents ..................................................................................................................................................................... 4

5.1.1 Regulated metals and other elements ........................................................................................................... 4

5.1.2 Organic and inorganic fluorine ............................................................................................................................ 4

5.1.3 Other hazardous substances ................................................................................................................................. 4

5.1.4 Volatile solids ...................................................................................................................................................................... 4

5.2 Ultimate aerobic biodegradation ............................................................................................................................................ 5

5.2.1 Test method and evaluation criteria ............................................................................................................... 5

5.2.2 Requirements regarding constituents ........................................................................................................... 5

5.3 Negative effects on terrestrial organism........................................................................................................................... 6

5.3.1 Ecotoxicity testing scheme ...................................................................................................................................... 6

5.3.2 Preparation of soils for ecotoxicity tests ..................................................................................................... 6

5.3.3 Acute toxicity plant growth test .......................................................................................................................... 7

5.3.4 Earthworm test ................................................................................................................................................................. 7

5.3.5 Nitrification inhibition test with soil microorganisms ................................................................... 8

6 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Examples of maximum concentrations of regulated metals and other

elements .....................................................................................................................................................................................................................10

Annex B (normative) Maximum concentrations of organic and inorganic fluorine and other

hazardous substances ..................................................................................................................................................................................11

Annex C (normative) Determination of acute effects of materials on the emergence and

growth of higher plants ..............................................................................................................................................................................13

Annex D (normative) Determination of acute effects of materials on earthworms .........................................15

Annex E (normative) Determination of effects on reproduction of earthworms................................................16

Annex F (normative) Determination of nitrification of soil microorganisms ........................................................17

Annex G (normative) Preparation of soils for ecotoxicity testing .......................................................................................18

Annex H (informative) Visual surface evaluation method of the disintegration in a slide

frame test ..................................................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................24

© ISO 2021 – All rights reserved iii
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ISO/FDIS 23517:2021(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 61, Plastics, Subcommittee SC 14,

Environmental aspects.

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 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
Introduction

Biodegradable mulch films are used worldwide in agriculture and horticulture for many years. They

enhance growing conditions and contribute to increased yields and improved crop quality by, for

example:
— inhibiting the development of weeds;
— reducing significantly the consumption of water and other resources;
— control of soil temperature;
— reduction in leaching of mineral elements and other fertilizer;
— reduction in soil compaction;
— protecting the crops from soil.

Biodegradable mulch films are not designed to be recovered from soil at the end of the intended service

life. Therefore, it is no longer necessary for farmers to retrieve the biodegradable mulch film from the

field for disposal or recycling after the harvest. Farmers can simply plow it under along with what

remains from the plants so that it is incorporated into soil.

This document defines the standard specification to be met for biodegradable mulch films to be

used in agriculture and horticulture. It is suited to characterize both the plastic materials which are

used to manufacture mulch films and the mulch films itself with respect to characteristics such as

biodegradation, adverse effects on terrestrial organisms and control of constituents.

© ISO 2021 – All rights reserved v
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23517:2021(E)
Plastics — Soil biodegradable materials for mulch films for
use in agriculture and horticulture — Requirements and
test methods regarding biodegradation, ecotoxicity and
control of constituents
1 Scope

This document is applicable to biodegradable plastic materials used to produce mulch films or

biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture.

This document specifies test methods and evaluation criteria by addressing the following

characteristics:
a) control of constituents;
b) biodegradation;
c) negative effects on terrestrial organisms.

NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic

products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

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 10390, Soil quality — Determination of pH

ISO 11268­1, Soil quality — Effects of pollutants on earthworms — Part 1: Determination of acute toxicity

to Eisenia fetida/Eisenia andrei

ISO 11268­2, Soil quality — Effects of pollutants on earthworms — Part 2: Determination of effects on

reproduction of Eisenia fetida/Eisenia andrei

ISO 11269­2, Soil quality — Determination of the effects of pollutants on soil flora — Part 2: Effects of

contaminated soil on the emergence and early growth of higher plants

ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods

EN 14582, Characterization of waste — Halogen and sulfur content — Oxygen combustion in closed

systems and determination methods

ISO 15685, Soil quality — Determination of potential nitrification and inhibition of nitrification — Rapid

test by ammonium oxidation

ISO 17556, Plastics — Determination of the ultimate aerobic biodegradability of plastic materials in soil by

measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

OECD. (2006), Test No. 208: Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, OECD

Guidelines for the Testing of Chemicals, Section 2
© ISO 2021 – All rights reserved 1
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ISO/FDIS 23517:2021(E)
3 Terms and definitions
For 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.el ectropedia. org/
3.1
mulch film

film made from thermoplastic material intended to be used in agriculture and horticulture to cover the

ground in order to improve growing conditions of crops and depending on the colour to control weeds

Note 1 to entry: It is assumed that a transparent mulch film does not allow to control weeds.

[SOURCE: EN 17033:2018, 3.1.1]
3.2
material

homogenous preparation of biodegradable polymer and additives, as necessary, such as carbon black

and colour pigments

Note 1 to entry: Additives are usually introduced under the form of masterbatches using as carrier resin a

biodegradable polymer.
[SOURCE: EN 17033:2018, 3.1.2]
3.3
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

[SOURCE: ISO 17088:2021, 3.9]
3.4
mineralization

decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides,

oxides or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]
3.5
disintegration
physical breakdown of a material into fragments
[SOURCE: ISO 18606:2013, 3.3]
3.6
degradation

irreversible process leading to a significant change in the structure of a material, typically characterized

by a change of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by

fragmentation, affected by environmental conditions, proceeding over a period of time and comprising

one or more steps
[SOURCE: ISO 472:2013, 2.262]
2 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
3.7
total dry solid

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
[SOURCE: ISO 17088:2021, 3.8]
3.8
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids (3.7) of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

[SOURCE: ISO 17088:2021, 3.10]
3.9
organic constituent

chemical constituent that contains carbon covalently linked to other carbon atoms and to other

elements, most commonly hydrogen, oxygen or nitrogen

Note 1 to entry: Inorganic carbonates, carbides, cyanides and simple oxides such as carbon monoxide and carbon

dioxide are not considered as organic constituent.

Note 2 to entry: Allotropes of carbon, such as diamond, graphite, carbon black, fullerenes, and carbon nanotubes

are also not considered as organic constituent.
[SOURCE: ISO 17088:2021, 3.15]
3.10
natural soil
soil collected from the surface layer of fields and/or forests
[SOURCE: EN 17033:2018, 3.3.1]
3.11
poly- and perfluoroalkyl substances
PFAS

organofluorine compounds containing only carbon-fluorine bonds and carbon-carbon bonds but also

other heteroatoms
4 Basic requirements
4.1 General

In order to be identified as a biodegradable mulch film in accordance with this document, the mulch film

or the material of the mulch film under investigation shall fulfil all requirements specified in Clause 4

and Clause 5, respectively.
If not all requirements are met, no reference to this document shall be made.
4.2 Control of constituents

The mulch film or the material of the mulch film shall be identified and characterized prior to testing

including:
— determination of the presence of regulated metals and other elements;

— determination of the presence of organic [poly- and perfluoroalkyl substances (PFAS)] and inorganic

fluorine (determined as fluorine);
© ISO 2021 – All rights reserved 3
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ISO/FDIS 23517:2021(E)

— evaluation of the presence of other hazardous substance as specified in Annex B;

taking legal compliance into consideration.
In addition, volatile solids shall be determined.
4.3 Ultimate aerobic biodegradation

The ultimate level of aerobic biodegradation shall be established by testing under controlled conditions

as laid down in 5.2.1.
4.4 Negative effects on terrestrial organism

The mulch film or the material of the mulch film shall have no adverse effects on terrestrial organisms.

5 Detailed requirements
5.1 Control of constituents
5.1.1 Regulated metals and other elements

The concentrations of regulated metals and other elements in a mulch film or material of the mulch film

shall be less than 50 % of those prescribed for sludges, fertilizers and composts in the country where

the final product will be placed on the market or disposed of (see Annex A for examples).

Regulated metals and other elements shall be determined and reported.
5.1.2 Organic and inorganic fluorine
5.1.2.1 Organic fluorine (PFAS)

From a precautionary perspective, poly- and perfluoroalkyl substances (PFAS) shall not be intentionally

added to the mulch film or to a material of the mulch film.

NOTE Most of poly- and perfluoroalkyl substances (PFAS) are extremely persistent in the environment and

in addition, certain PFAS are suspected to have bioaccumulative properties and adverse effects for environment

and human health.
5.1.2.2 Inorganic fluorine

The concentration of inorganic fluorine in the mulch film or in a material of the mulch film shall be less

than 100 mg fluorine/kg material (dry matter) (see Annex B).
5.1.3 Other hazardous substances

From a precautionary perspective, hazardous substances as specified in Annex B shall not be

intentionally added to a mulch film or material of the mulch film.

Information on the use of hazardous substances shall be recorded and can be based on a self­declaration.

5.1.4 Volatile solids

A mulch film or material of a mulch film shall contain a minimum of 60 % of volatile solids.

Volatile solids shall be determined and reported.
4 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
5.2 Ultimate aerobic biodegradation
5.2.1 Test method and evaluation criteria

The ultimate aerobic biodegradability shall be determined for the whole material or for each organic

constituent.

Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or

an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to

ISO 17556.

The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil

if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as

specified hereunder:

a) 90 % of the organic carbon shall have been converted to CO by the end of the test period (relative

to a reference material). Both the reference material and the test item shall be tested for the same

length of time and the results compared at the same point in time;

b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to

carbon dioxide by the end of the test period.

If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then

the biodegradation test can be terminated. However, the test period shall be no longer than 2 years.

The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range

between 20 °C and 28 °C, preferably 25 °C.

Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder

or ashless cellulose filters). If possible, the physical form and size of the reference material should be

comparable to that of the test material.
The validity criteria as stated in ISO 17556 shall be fulfilled.

NOTE Biodegradability is assessed by measuring the mineralization level, i.e. the conversion of the organic

carbon of a product or a material into CO with the consumption of O under aerobic conditions, or into CO

2 2 2

and CH under anaerobic conditions. During biodegradation, part of the organic carbon is also assimilated as

biomass. This biomass yield typically ranges from 10 % to 40 %, depending on the substrate. As a consequence,

the mineralization level rarely reaches 100 % also when the biodegradation is 100 %, because of biomass

formation. Standard test methods for the accurate determination of product´s or material’s carbon assimilated in

biomass during biodegradation are not available yet.
5.2.2 Requirements regarding constituents

Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to

demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass).

For organic constituents which are present in the material at a concentration between 1 % and 15 % (by

dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in

5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to

be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301,

[30] [31]

Methods A to F ; OECD 310 ) are considered as biodegradable in the context of ISO 23517.

As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass),

the level of biodegradation of that organic constituent can be determined using an artificial blend of the

same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial

blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to

be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a

material on the condition that the co-substrate is present as tested in the artificial blend.

© ISO 2021 – All rights reserved 5
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ISO/FDIS 23517:2021(E)

Carbon black which is frequently used in mulch film is an inert solid. Therefore, it is not considered as

an organic constituent and shall not be accounted in the calculation of the degree of biodegradation.

NOTE The objective of testing an artificial blend is to demonstrate that a constituent which does not meet

the biodegradability requirements of ISO 23517 when tested alone, may become biodegradable in combination

with another biodegradable constituents of a material. The concentration of the constituent in the artificial

blend was set at a minimum of 15 % in order to avoid false-positive results, as theoretically a material with, for

example, 10 % of a non or moderately biodegradable constituent may still reach the pass level for biodegradation

specified in 5.2.1.
5.3 Negative effects on terrestrial organism
5.3.1 Ecotoxicity testing scheme

Ecotoxicity tests shall be performed in order to investigate possible adverse effects caused by

degradation products resulting from the degradation of the material of a mulch film in soil at the end of

the intended service life.
The test scheme takes into account:

— all relevant terrestrial organism groups as plants, earthworms (invertebrates) and microorganisms;

— important ecological processes critical due to their role in maintaining soil functions as breakdown

of organic matter, formulation of soil structure and cycling of materials;

— all relevant exposure pathways as soil pore water, soil pore air and soil material.

The link between soil organism groups of major ecological importance covering all significant soil

exposure pathways and suitable test methods for the evaluation of ecotoxicity of the materials of mulch

films and their degradation products is shown in Table 1.
Table 1 — Test scheme for the assessment of ecotoxicity
Organism group Ecological process Soil exposure pathway Test methods
plant growth test according to
plants: mainly soil pore water
primary production OECD 208 or ISO 11269­2 with the
­ higher plants (by root uptake)
modifications specified in Annex C
diverse and multiple up­
take routes: acute earthworm test according to
ISO 11268-1 with the modifications
breakdown of organic ­ soil pore water;
invertebrates:
specified in Annex D or alternative­
matter; formation of
­ ingestion of soil ly chronic earthworm toxicity test
­ earthworms
soil structure
according to ISO 11268­2 with the
material;
modifications laid down in Annex E
­ soil air
nitrification inhibition test with
microorganisms:
soil microorganisms according to
recycling of nutrients mainly soil pore water
ISO 15685 with the modifications
­ bacteria
specified in Annex F

Ecotoxic effects on terrestrial organism shall be determined by comparing soils produced with or

without the addition of a test material.
5.3.2 Preparation of soils for ecotoxicity tests

The ecotoxicity of degradation products shall be evaluated according to the test methods specified in

5.3.3, 5.3.4 and 5.3.5 using test soils prepared according to Annex G.
6 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)

The initial test item concentration in the reactor with test material shall be 1 % dry weight.

NOTE Rationale for an initial test item concentration of 1 %: a 1 % loading is much higher than the expected

application loading of a biodegradable mulch film on soil. For example: a typical mulch film is 1,5 × 10 m thick

­3 −2 ­2

and has a density of 1 250 kg m . This means 1,875 × 10 kg m for one application. The soil depth where

a mulch film is typically used or remains after use is presumed to be 0,20 m, in agreement with the normal

2 2

depth of soil tillage. Therefore, 1 m of mulch film covering 1 m of soil surface will typically be mixed with a

volume of soil equal to 0,2 m . This amount of soil weighs approximately 300 kg, considering a soil bulk density

of 1 500 kg m . Therefore, the typical loading of the mulch film in normal use will be approximately 0,006 3 %

(1,875 × 10 kg/300 kg × 100) which is far below the initial test item concentration of 1 % taking into account

also various film thickness and repeated applications.
5.3.3 Acute toxicity plant growth test

The purpose of this test is to determine the possible toxic effects of mulch films incorporated in soil

on the emergence, the early stages of growth and development of terrestrial plants. The basis for the

determination is OECD 208 or, alternatively, ISO 11269-2. The principles of the standard test methods

shall be followed with the modifications given in the Annex C.

The germination rate and the plant biomass of the tested plant species in the soil exposed to the test

material shall be more than 90 % of those from the corresponding blank soil not exposed to the te

...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23517
ISO/TC 61/SC 14
Plastics — Soil biodegradable
Secretariat: DIN
materials for mulch films for use
Voting begins on:
2021­05­03 in agriculture and horticulture —
Requirements and test methods
Voting terminates on:
2021­06­28
regarding biodegradation,
ecotoxicity and control of
constituents
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/FDIS 23517:2021(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 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23517:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Basic requirements ............................................................................................................................................................................................ 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Control of constituents ..................................................................................................................................................................... 3

4.3 Ultimate aerobic biodegradation ............................................................................................................................................ 4

4.4 Negative effects on terrestrial organism........................................................................................................................... 4

5 Detailed requirements ................................................................................................................................................................................... 4

5.1 Control of constituents ..................................................................................................................................................................... 4

5.1.1 Regulated metals and other elements ........................................................................................................... 4

5.1.2 Organic and inorganic fluorine ............................................................................................................................ 4

5.1.3 Other hazardous substances ................................................................................................................................. 4

5.1.4 Volatile solids ...................................................................................................................................................................... 4

5.2 Ultimate aerobic biodegradation ............................................................................................................................................ 5

5.2.1 Test method and evaluation criteria ............................................................................................................... 5

5.2.2 Requirements regarding constituents ........................................................................................................... 5

5.3 Negative effects on terrestrial organism........................................................................................................................... 6

5.3.1 Ecotoxicity testing scheme ...................................................................................................................................... 6

5.3.2 Preparation of soils for ecotoxicity tests ..................................................................................................... 6

5.3.3 Acute toxicity plant growth test .......................................................................................................................... 7

5.3.4 Earthworm test ................................................................................................................................................................. 7

5.3.5 Nitrification inhibition test with soil microorganisms ................................................................... 8

6 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Examples of maximum concentrations of regulated metals and other

elements .....................................................................................................................................................................................................................10

Annex B (normative) Maximum concentrations of organic and inorganic fluorine and other

hazardous substances ..................................................................................................................................................................................11

Annex C (normative) Determination of acute effects of materials on the emergence and

growth of higher plants ..............................................................................................................................................................................13

Annex D (normative) Determination of acute effects of materials on earthworms .........................................15

Annex E (normative) Determination of effects on reproduction of earthworms................................................16

Annex F (normative) Determination of nitrification of soil microorganisms ........................................................17

Annex G (normative) Preparation of soils for ecotoxicity testing .......................................................................................18

Annex H (informative) Visual surface evaluation method of the disintegration in a slide

frame test ..................................................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................24

© ISO 2021 – All rights reserved iii
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ISO/FDIS 23517:2021(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 61, Plastics, Subcommittee SC 14,

Environmental aspects.

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 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
Introduction

Biodegradable mulch films are used worldwide in agriculture and horticulture for many years. They

enhance growing conditions and contribute to increased yields and improved crop quality by, for

example:
— inhibiting the development of weeds;
— reducing significantly the consumption of water and other resources;
— control of soil temperature;
— reduction in leaching of mineral elements and other fertilizer;
— reduction in soil compaction;
— protecting the crops from soil.

Biodegradable mulch films are not designed to be recovered from soil at the end of the intended service

life. Therefore, it is no longer necessary for farmers to retrieve the biodegradable mulch film from the

field for disposal or recycling after the harvest. Farmers can simply plow it under along with what

remains from the plants so that it is incorporated into soil.

This document defines the standard specification to be met for biodegradable mulch films to be

used in agriculture and horticulture. It is suited to characterize both the plastic materials which are

used to manufacture mulch films and the mulch films itself with respect to characteristics such as

biodegradation, adverse effects on terrestrial organisms and control of constituents.

© ISO 2021 – All rights reserved v
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23517:2021(E)
Plastics — Soil biodegradable materials for mulch films for
use in agriculture and horticulture — Requirements and
test methods regarding biodegradation, ecotoxicity and
control of constituents
1 Scope

This document is applicable to biodegradable plastic materials used to produce mulch films or

biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture.

This document specifies test methods and evaluation criteria by addressing the following

characteristics:
a) control of constituents;
b) biodegradation;
c) negative effects on terrestrial organisms.

NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic

products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

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 10390, Soil quality — Determination of pH

ISO 11268­1, Soil quality — Effects of pollutants on earthworms — Part 1: Determination of acute toxicity

to Eisenia fetida/Eisenia andrei

ISO 11268­2, Soil quality — Effects of pollutants on earthworms — Part 2: Determination of effects on

reproduction of Eisenia fetida/Eisenia andrei

ISO 11269­2, Soil quality — Determination of the effects of pollutants on soil flora — Part 2: Effects of

contaminated soil on the emergence and early growth of higher plants

ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods

EN 14582, Characterization of waste — Halogen and sulfur content — Oxygen combustion in closed

systems and determination methods

ISO 15685, Soil quality — Determination of potential nitrification and inhibition of nitrification — Rapid

test by ammonium oxidation

ISO 17556, Plastics — Determination of the ultimate aerobic biodegradability of plastic materials in soil by

measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

OECD. (2006), Test No. 208: Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, OECD

Guidelines for the Testing of Chemicals, Section 2
© ISO 2021 – All rights reserved 1
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ISO/FDIS 23517:2021(E)
3 Terms and definitions
For 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.el ectropedia. org/
3.1
mulch film

film made from thermoplastic material intended to be used in agriculture and horticulture to cover the

ground in order to improve growing conditions of crops and depending on the colour to control weeds

Note 1 to entry: It is assumed that a transparent mulch film does not allow to control weeds.

[SOURCE: EN 17033:2018, 3.1.1]
3.2
material

homogenous preparation of biodegradable polymer and additives, as necessary, such as carbon black

and colour pigments

Note 1 to entry: Additives are usually introduced under the form of masterbatches using as carrier resin a

biodegradable polymer.
[SOURCE: EN 17033:2018, 3.1.2]
3.3
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

[SOURCE: ISO 17088:2021, 3.9]
3.4
mineralization

decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides,

oxides or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]
3.5
disintegration
physical breakdown of a material into fragments
[SOURCE: ISO 18606:2013, 3.3]
3.6
degradation

irreversible process leading to a significant change in the structure of a material, typically characterized

by a change of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by

fragmentation, affected by environmental conditions, proceeding over a period of time and comprising

one or more steps
[SOURCE: ISO 472:2013, 2.262]
2 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
3.7
total dry solid

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
[SOURCE: ISO 17088:2021, 3.8]
3.8
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids (3.7) of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

[SOURCE: ISO 17088:2021, 3.10]
3.9
organic constituent

chemical constituent that contains carbon covalently linked to other carbon atoms and to other

elements, most commonly hydrogen, oxygen or nitrogen

Note 1 to entry: Inorganic carbonates, carbides, cyanides and simple oxides such as carbon monoxide and carbon

dioxide are not considered as organic constituent.

Note 2 to entry: Allotropes of carbon, such as diamond, graphite, carbon black, fullerenes, and carbon nanotubes

are also not considered as organic constituent.
[SOURCE: ISO 17088:2021, 3.15]
3.10
natural soil
soil collected from the surface layer of fields and/or forests
[SOURCE: EN 17033:2018, 3.3.1]
3.11
poly- and perfluoroalkyl substances
PFAS

organofluorine compounds containing only carbon-fluorine bonds and carbon-carbon bonds but also

other heteroatoms
4 Basic requirements
4.1 General

In order to be identified as a biodegradable mulch film in accordance with this document, the mulch film

or the material of the mulch film under investigation shall fulfil all requirements specified in Clause 4

and Clause 5, respectively.
If not all requirements are met, no reference to this document shall be made.
4.2 Control of constituents

The mulch film or the material of the mulch film shall be identified and characterized prior to testing

including:
— determination of the presence of regulated metals and other elements;

— determination of the presence of organic [poly- and perfluoroalkyl substances (PFAS)] and inorganic

fluorine (determined as fluorine);
© ISO 2021 – All rights reserved 3
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ISO/FDIS 23517:2021(E)

— evaluation of the presence of other hazardous substance as specified in Annex B;

taking legal compliance into consideration.
In addition, volatile solids shall be determined.
4.3 Ultimate aerobic biodegradation

The ultimate level of aerobic biodegradation shall be established by testing under controlled conditions

as laid down in 5.2.1.
4.4 Negative effects on terrestrial organism

The mulch film or the material of the mulch film shall have no adverse effects on terrestrial organisms.

5 Detailed requirements
5.1 Control of constituents
5.1.1 Regulated metals and other elements

The concentrations of regulated metals and other elements in a mulch film or material of the mulch film

shall be less than 50 % of those prescribed for sludges, fertilizers and composts in the country where

the final product will be placed on the market or disposed of (see Annex A for examples).

Regulated metals and other elements shall be determined and reported.
5.1.2 Organic and inorganic fluorine
5.1.2.1 Organic fluorine (PFAS)

From a precautionary perspective, poly- and perfluoroalkyl substances (PFAS) shall not be intentionally

added to the mulch film or to a material of the mulch film.

NOTE Most of poly- and perfluoroalkyl substances (PFAS) are extremely persistent in the environment and

in addition, certain PFAS are suspected to have bioaccumulative properties and adverse effects for environment

and human health.
5.1.2.2 Inorganic fluorine

The concentration of inorganic fluorine in the mulch film or in a material of the mulch film shall be less

than 100 mg fluorine/kg material (dry matter) (see Annex B).
5.1.3 Other hazardous substances

From a precautionary perspective, hazardous substances as specified in Annex B shall not be

intentionally added to a mulch film or material of the mulch film.

Information on the use of hazardous substances shall be recorded and can be based on a self­declaration.

5.1.4 Volatile solids

A mulch film or material of a mulch film shall contain a minimum of 60 % of volatile solids.

Volatile solids shall be determined and reported.
4 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
5.2 Ultimate aerobic biodegradation
5.2.1 Test method and evaluation criteria

The ultimate aerobic biodegradability shall be determined for the whole material or for each organic

constituent.

Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or

an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to

ISO 17556.

The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil

if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as

specified hereunder:

a) 90 % of the organic carbon shall have been converted to CO by the end of the test period (relative

to a reference material). Both the reference material and the test item shall be tested for the same

length of time and the results compared at the same point in time;

b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to

carbon dioxide by the end of the test period.

If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then

the biodegradation test can be terminated. However, the test period shall be no longer than 2 years.

The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range

between 20 °C and 28 °C, preferably 25 °C.

Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder

or ashless cellulose filters). If possible, the physical form and size of the reference material should be

comparable to that of the test material.
The validity criteria as stated in ISO 17556 shall be fulfilled.

NOTE Biodegradability is assessed by measuring the mineralization level, i.e. the conversion of the organic

carbon of a product or a material into CO with the consumption of O under aerobic conditions, or into CO

2 2 2

and CH under anaerobic conditions. During biodegradation, part of the organic carbon is also assimilated as

biomass. This biomass yield typically ranges from 10 % to 40 %, depending on the substrate. As a consequence,

the mineralization level rarely reaches 100 % also when the biodegradation is 100 %, because of biomass

formation. Standard test methods for the accurate determination of product´s or material’s carbon assimilated in

biomass during biodegradation are not available yet.
5.2.2 Requirements regarding constituents

Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to

demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass).

For organic constituents which are present in the material at a concentration between 1 % and 15 % (by

dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in

5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to

be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301,

[30] [31]

Methods A to F ; OECD 310 ) are considered as biodegradable in the context of ISO 23517.

As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass),

the level of biodegradation of that organic constituent can be determined using an artificial blend of the

same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial

blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to

be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a

material on the condition that the co-substrate is present as tested in the artificial blend.

© ISO 2021 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/FDIS 23517:2021(E)

Carbon black which is frequently used in mulch film is an inert solid. Therefore, it is not considered as

an organic constituent and shall not be accounted in the calculation of the degree of biodegradation.

NOTE The objective of testing an artificial blend is to demonstrate that a constituent which does not meet

the biodegradability requirements of ISO 23517 when tested alone, may become biodegradable in combination

with another biodegradable constituents of a material. The concentration of the constituent in the artificial

blend was set at a minimum of 15 % in order to avoid false-positive results, as theoretically a material with, for

example, 10 % of a non or moderately biodegradable constituent may still reach the pass level for biodegradation

specified in 5.2.1.
5.3 Negative effects on terrestrial organism
5.3.1 Ecotoxicity testing scheme

Ecotoxicity tests shall be performed in order to investigate possible adverse effects caused by

degradation products resulting from the degradation of the material of a mulch film in soil at the end of

the intended service life.
The test scheme takes into account:

— all relevant terrestrial organism groups as plants, earthworms (invertebrates) and microorganisms;

— important ecological processes critical due to their role in maintaining soil functions as breakdown

of organic matter, formulation of soil structure and cycling of materials;

— all relevant exposure pathways as soil pore water, soil pore air and soil material.

The link between soil organism groups of major ecological importance covering all significant soil

exposure pathways and suitable test methods for the evaluation of ecotoxicity of the materials of mulch

films and their degradation products is shown in Table 1.
Table 1 — Test scheme for the assessment of ecotoxicity
Organism group Ecological process Soil exposure pathway Test methods
plant growth test according to
plants: mainly soil pore water
primary production OECD 208 or ISO 11269­2 with the
­ higher plants (by root uptake)
modifications specified in Annex C
diverse and multiple up­
take routes: acute earthworm test according to
ISO 11268-1 with the modifications
breakdown of organic ­ soil pore water;
invertebrates:
specified in Annex D or alternative­
matter; formation of
­ ingestion of soil ly chronic earthworm toxicity test
­ earthworms
soil structure
according to ISO 11268­2 with the
material;
modifications laid down in Annex E
­ soil air
nitrification inhibition test with
microorganisms:
soil microorganisms according to
recycling of nutrients mainly soil pore water
ISO 15685 with the modifications
­ bacteria
specified in Annex F

Ecotoxic effects on terrestrial organism shall be determined by comparing soils produced with or

without the addition of a test material.
5.3.2 Preparation of soils for ecotoxicity tests

The ecotoxicity of degradation products shall be evaluated according to the test methods specified in

5.3.3, 5.3.4 and 5.3.5 using test soils prepared according to Annex G.
6 © ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/FDIS 23517:2021(E)

The initial test item concentration in the reactor with test material shall be 1 % dry weight.

NOTE Rationale for an initial test item concentration of 1 %: a 1 % loading is much higher than the expected

application loading of a biodegradable mulch film on soil. For example: a typical mulch film is 1,5 × 10 m thick

­3 −2 ­2

and has a density of 1 250 kg m . This means 1,875 × 10 kg m for one application. The soil depth where

a mulch film is typically used or remains after use is presumed to be 0,20 m, in agreement with the normal

2 2

depth of soil tillage. Therefore, 1 m of mulch film covering 1 m of soil surface will typically be mixed with a

volume of soil equal to 0,2 m . This amount of soil weighs approximately 300 kg, considering a soil bulk density

of 1 500 kg m . Therefore, the typical loading of the mulch film in normal use will be approximately 0,006 3 %

(1,875 × 10 kg/300 kg × 100) which is far below the initial test item concentration of 1 % taking into account

also various film thickness and repeated applications.
5.3.3 Acute toxicity plant growth test

The purpose of this test is to determine the possible toxic effects of mulch films incorporated in soil

on the emergence, the early stages of growth and development of terrestrial plants. The basis for the

determination is OECD 208 or, alternatively, ISO 11269-2. The principles of the standard test methods

shall be followed with the modifications given in the Annex C.

The germination rate and the plant biomass of the tested plant species in the soil exposed to the test

material shall be more than 90 % of those from the corresponding blank soil not exposed to the te

...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23517
ISO/TC 61/SC 14
Plastics — Soil biodegradable
Secretariat: DIN
materials for mulch films for use
Voting begins on:
2021­05­03 in agriculture and horticulture —
Requirements and test methods
Voting terminates on:
2021­06­28
regarding biodegradation,
ecotoxicity and control of
constituents
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/FDIS 23517:2021(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 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23517:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 23517:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Basic requirements ............................................................................................................................................................................................ 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Control of constituents ..................................................................................................................................................................... 3

4.3 Ultimate aerobic biodegradation ............................................................................................................................................ 4

4.4 Negative effects on terrestrial organism........................................................................................................................... 4

5 Detailed requirements ................................................................................................................................................................................... 4

5.1 Control of constituents ..................................................................................................................................................................... 4

5.1.1 Regulated metals and other elements ........................................................................................................... 4

5.1.2 Organic and inorganic fluorine ............................................................................................................................ 4

5.1.3 Other hazardous substances ................................................................................................................................. 4

5.1.4 Volatile solids ...................................................................................................................................................................... 4

5.2 Ultimate aerobic biodegradation ............................................................................................................................................ 5

5.2.1 Test method and evaluation criteria ............................................................................................................... 5

5.2.2 Requirements regarding constituents ........................................................................................................... 5

5.3 Negative effects on terrestrial organism........................................................................................................................... 6

5.3.1 Ecotoxicity testing scheme ...................................................................................................................................... 6

5.3.2 Preparation of soils for ecotoxicity tests ..................................................................................................... 6

5.3.3 Acute toxicity plant growth test .......................................................................................................................... 7

5.3.4 Earthworm test ................................................................................................................................................................. 7

5.3.5 Nitrification inhibition test with soil microorganisms ................................................................... 8

6 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Examples of maximum concentrations of regulated metals and other

elements .....................................................................................................................................................................................................................10

Annex B (normative) Maximum concentrations of organic and inorganic fluorine and other

hazardous substances ..................................................................................................................................................................................11

Annex C (normative) Determination of acute effects of materials on the emergence and

growth of higher plants ..............................................................................................................................................................................13

Annex D (normative) Determination of acute effects of materials on earthworms .........................................15

Annex E (normative) Determination of effects on reproduction of earthworms................................................16

Annex F (normative) Determination of nitrification of soil microorganisms ........................................................17

Annex G (normative) Preparation of soils for ecotoxicity testing .......................................................................................18

Annex H (informative) Visual surface evaluation method of the disintegration in a slide

frame test ..................................................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................24

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23517:2021(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 61, Plastics, Subcommittee SC 14,

Environmental aspects.

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 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23517:2021(E)
Introduction

Biodegradable mulch films are used worldwide in agriculture and horticulture for many years. They

enhance growing conditions and contribute to increased yields and improved crop quality by, for

example:
— inhibiting the development of weeds;
— reducing significantly the consumption of water and other resources;
— control of soil temperature;
— reduction in leaching of mineral elements and other fertilizer;
— reduction in soil compaction;
— protecting the crops from soil.

Biodegradable mulch films are not designed to be recovered from soil at the end of the intended service

life. Therefore, it is no longer necessary for farmers to retrieve the biodegradable mulch film from the

field for disposal or recycling after the harvest. Farmers can simply plow it under along with what

remains from the plants so that it is incorporated into soil.

This document defines the standard specification to be met for biodegradable mulch films to be

used in agriculture and horticulture. It is suited to characterize both the plastic materials which are

used to manufacture mulch films and the mulch films itself with respect to characteristics such as

biodegradation, adverse effects on terrestrial organisms and control of constituents.

© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23517:2021(E)
Plastics — Soil biodegradable materials for mulch films for
use in agriculture and horticulture — Requirements and
test methods regarding biodegradation, ecotoxicity and
control of constituents
1 Scope

This document is applicable to biodegradable plastic materials used to produce mulch films or

biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture.

This document specifies test methods and evaluation criteria by addressing the following

characteristics:
a) control of constituents;
b) biodegradation;
c) negative effects on terrestrial organisms.

NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic

products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

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 10390, Soil quality — Determination of pH

ISO 11268­1, Soil quality — Effects of pollutants on earthworms — Part 1: Determination of acute toxicity

to Eisenia fetida/Eisenia andrei

ISO 11268­2, Soil quality — Effects of pollutants on earthworms — Part 2: Determination of effects on

reproduction of Eisenia fetida/Eisenia andrei

ISO 11269­2, Soil quality — Determination of the effects of pollutants on soil flora — Part 2: Effects of

contaminated soil on the emergence and early growth of higher plants

ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods

EN 14582, Characterization of waste — Halogen and sulfur content — Oxygen combustion in closed

systems and determination methods

ISO 15685, Soil quality — Determination of potential nitrification and inhibition of nitrification — Rapid

test by ammonium oxidation

ISO 17556, Plastics — Determination of the ultimate aerobic biodegradability of plastic materials in soil by

measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

OECD. (2006), Test No. 208: Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, OECD

Guidelines for the Testing of Chemicals, Section 2
© ISO 2021 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/FDIS 23517:2021(E)
3 Terms and definitions
For 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.el ectropedia. org/
3.1
mulch film

film made from thermoplastic material intended to be used in agriculture and horticulture to cover the

ground in order to improve growing conditions of crops and depending on the colour to control weeds

Note 1 to entry: It is assumed that a transparent mulch film does not allow to control weeds.

[SOURCE: EN 17033:2018, 3.1.1]
3.2
material

homogenous preparation of biodegradable polymer and additives, as necessary, such as carbon black

and colour pigments

Note 1 to entry: Additives are usually introduced under the form of masterbatches using as carrier resin a

biodegradable polymer.
[SOURCE: EN 17033:2018, 3.1.2]
3.3
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

[SOURCE: ISO 17088:2021, 3.9]
3.4
mineralization

decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides,

oxides or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]
3.5
disintegration
physical breakdown of a material into fragments
[SOURCE: ISO 18606:2013, 3.3]
3.6
degradation

irreversible process leading to a significant change in the structure of a material, typically characterized

by a change of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by

fragmentation, affected by environmental conditions, proceeding over a period of time and comprising

one or more steps
[SOURCE: ISO 472:2013, 2.262]
2 © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/FDIS 23517:2021(E)
3.7
total dry solid

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
[SOURCE: ISO 17088:2021, 3.8]
3.8
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids (3.7) of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

[SOURCE: ISO 17088:2021, 3.10]
3.9
organic constituent

chemical constituent that contains carbon covalently linked to other carbon atoms and to other

elements, most commonly hydrogen, oxygen or nitrogen

Note 1 to entry: Inorganic carbonates, carbides, cyanides and simple oxides such as carbon monoxide and carbon

dioxide are not considered as organic constituent.

Note 2 to entry: Allotropes of carbon, such as diamond, graphite, carbon black, fullerenes, and carbon nanotubes

are also not considered as organic constituent.
[SOURCE: ISO 17088:2021, 3.15]
3.10
natural soil
soil collected from the surface layer of fields and/or forests
[SOURCE: EN 17033:2018, 3.3.1]
3.11
poly- and perfluoroalkyl substances
PFAS

organofluorine compounds containing only carbon-fluorine bonds and carbon-carbon bonds but also

other heteroatoms
4 Basic requirements
4.1 General

In order to be identified as a biodegradable mulch film in accordance with this document, the mulch film

or the material of the mulch film under investigation shall fulfil all requirements specified in Clause 4

and Clause 5, respectively.
If not all requirements are met, no reference to this document shall be made.
4.2 Control of constituents

The mulch film or the material of the mulch film shall be identified and characterized prior to testing

including:
— determination of the presence of regulated metals and other elements;

— determination of the presence of organic [poly- and perfluoroalkyl substances (PFAS)] and inorganic

fluorine (determined as fluorine);
© ISO 2021 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO/FDIS 23517:2021(E)

— evaluation of the presence of other hazardous substance as specified in Annex B;

taking legal compliance into consideration.
In addition, volatile solids shall be determined.
4.3 Ultimate aerobic biodegradation

The ultimate level of aerobic biodegradation shall be established by testing under controlled conditions

as laid down in 5.2.1.
4.4 Negative effects on terrestrial organism

The mulch film or the material of the mulch film shall have no adverse effects on terrestrial organisms.

5 Detailed requirements
5.1 Control of constituents
5.1.1 Regulated metals and other elements

The concentrations of regulated metals and other elements in a mulch film or material of the mulch film

shall be less than 50 % of those prescribed for sludges, fertilizers and composts in the country where

the final product will be placed on the market or disposed of (see Annex A for examples).

Regulated metals and other elements shall be determined and reported.
5.1.2 Organic and inorganic fluorine
5.1.2.1 Organic fluorine (PFAS)

From a precautionary perspective, poly- and perfluoroalkyl substances (PFAS) shall not be intentionally

added to the mulch film or to a material of the mulch film.

NOTE Most of poly- and perfluoroalkyl substances (PFAS) are extremely persistent in the environment and

in addition, certain PFAS are suspected to have bioaccumulative properties and adverse effects for environment

and human health.
5.1.2.2 Inorganic fluorine

The concentration of inorganic fluorine in the mulch film or in a material of the mulch film shall be less

than 100 mg fluorine/kg material (dry matter) (see Annex B).
5.1.3 Other hazardous substances

From a precautionary perspective, hazardous substances as specified in Annex B shall not be

intentionally added to a mulch film or material of the mulch film.

Information on the use of hazardous substances shall be recorded and can be based on a self­declaration.

5.1.4 Volatile solids

A mulch film or material of a mulch film shall contain a minimum of 60 % of volatile solids.

Volatile solids shall be determined and reported.
4 © ISO 2021 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/FDIS 23517:2021(E)
5.2 Ultimate aerobic biodegradation
5.2.1 Test method and evaluation criteria

The ultimate aerobic biodegradability shall be determined for the whole material or for each organic

constituent.

Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or

an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to

ISO 17556.

The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil

if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as

specified hereunder:

a) 90 % of the organic carbon shall have been converted to CO by the end of the test period (relative

to a reference material). Both the reference material and the test item shall be tested for the same

length of time and the results compared at the same point in time;

b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to

carbon dioxide by the end of the test period.

If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then

the biodegradation test can be terminated. However, the test period shall be no longer than 2 years.

The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range

between 20 °C and 28 °C, preferably 25 °C.

Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder

or ashless cellulose filters). If possible, the physical form and size of the reference material should be

comparable to that of the test material.
The validity criteria as stated in ISO 17556 shall be fulfilled.

NOTE Biodegradability is assessed by measuring the mineralization level, i.e. the conversion of the organic

carbon of a product or a material into CO with the consumption of O under aerobic conditions, or into CO

2 2 2

and CH under anaerobic conditions. During biodegradation, part of the organic carbon is also assimilated as

biomass. This biomass yield typically ranges from 10 % to 40 %, depending on the substrate. As a consequence,

the mineralization level rarely reaches 100 % also when the biodegradation is 100 %, because of biomass

formation. Standard test methods for the accurate determination of product´s or material’s carbon assimilated in

biomass during biodegradation are not available yet.
5.2.2 Requirements regarding constituents

Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to

demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass).

For organic constituents which are present in the material at a concentration between 1 % and 15 % (by

dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in

5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to

be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301,

[30] [31]

Methods A to F ; OECD 310 ) are considered as biodegradable in the context of ISO 23517.

As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass),

the level of biodegradation of that organic constituent can be determined using an artificial blend of the

same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial

blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to

be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a

material on the condition that the co-substrate is present as tested in the artificial blend.

© ISO 2021 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/FDIS 23517:2021(E)

Carbon black which is frequently used in mulch film is an inert solid. Therefore, it is not considered as

an organic constituent and shall not be accounted in the calculation of the degree of biodegradation.

NOTE The objective of testing an artificial blend is to demonstrate that a constituent which does not meet

the biodegradability requirements of ISO 23517 when tested alone, may become biodegradable in combination

with another biodegradable constituents of a material. The concentration of the constituent in the artificial

blend was set at a minimum of 15 % in order to avoid false-positive results, as theoretically a material with, for

example, 10 % of a non or moderately biodegradable constituent may still reach the pass level for biodegradation

specified in 5.2.1.
5.3 Negative effects on terrestrial organism
5.3.1 Ecotoxicity testing scheme

Ecotoxicity tests shall be performed in order to investigate possible adverse effects caused by

degradation products resulting from the degradation of the material of a mulch film in soil at the end of

the intended service life.
The test scheme takes into account:

— all relevant terrestrial organism groups as plants, earthworms (invertebrates) and microorganisms;

— important ecological processes critical due to their role in maintaining soil functions as breakdown

of organic matter, formulation of soil structure and cycling of materials;

— all relevant exposure pathways as soil pore water, soil pore air and soil material.

The link between soil organism groups of major ecological importance covering all significant soil

exposure pathways and suitable test methods for the evaluation of ecotoxicity of the materials of mulch

films and their degradation products is shown in Table 1.
Table 1 — Test scheme for the assessment of ecotoxicity
Organism group Ecological process Soil exposure pathway Test methods
plant growth test according to
plants: mainly soil pore water
primary production OECD 208 or ISO 11269­2 with the
­ higher plants (by root uptake)
modifications specified in Annex C
diverse and multiple up­
take routes: acute earthworm test according to
ISO 11268-1 with the modifications
breakdown of organic ­ soil pore water;
invertebrates:
specified in Annex D or alternative­
matter; formation of
­ ingestion of soil ly chronic earthworm toxicity test
­ earthworms
soil structure
according to ISO 11268­2 with the
material;
modifications laid down in Annex E
­ soil air
nitrification inhibition test with
microorganisms:
soil microorganisms according to
recycling of nutrients mainly soil pore water
ISO 15685 with the modifications
­ bacteria
specified in Annex F

Ecotoxic effects on terrestrial organism shall be determined by comparing soils produced with or

without the addition of a test material.
5.3.2 Preparation of soils for ecotoxicity tests

The ecotoxicity of degradation products shall be evaluated according to the test methods specified in

5.3.3, 5.3.4 and 5.3.5 using test soils prepared according to Annex G.
6 © ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/FDIS 23517:2021(E)

The initial test item concentration in the reactor with test material shall be 1 % dry weight.

NOTE Rationale for an initial test item concentration of 1 %: a 1 % loading is much higher than the expected

application loading of a biodegradable mulch film on soil. For example: a typical mulch film is 1,5 × 10 m thick

­3 −2 ­2

and has a density of 1 250 kg m . This means 1,875 × 10 kg m for one application. The soil depth where

a mulch film is typically used or remains after use is presumed to be 0,20 m, in agreement with the normal

2 2

depth of soil tillage. Therefore, 1 m of mulch film covering 1 m of soil surface will typically be mixed with a

volume of soil equal to 0,2 m . This amount of soil weighs approximately 300 kg, considering a soil bulk density

of 1 500 kg m . Therefore, the typical loading of the mulch film in normal use will be approximately 0,006 3 %

(1,875 × 10 kg/300 kg × 100) which is far below the initial test item concentration of 1 % taking into account

also various film thickness and repeated applications.
5.3.3 Acute toxicity plant growth test

The purpose of this test is to determine the possible toxic effects of mulch films incorporated in soil

on the emergence, the early stages of growth and development of terrestrial plants. The basis for the

determination is OECD 208 or, alternatively, ISO 11269-2. The principles of the standard test methods

shall be followed with the modifications given in the Annex C.

The germination rate and the plant biomass of the tested plant species in the soil exposed to the test

material shall be more than 90 % of those from the corresponding blank soil not exposed to the te

...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23517
ISO/TC 61/SC 14
Plastics — Soil biodegradable
Secretariat: DIN
materials for mulch films for use
Voting begins on:
2021­05­03 in agriculture and horticulture —
Requirements and test methods
Voting terminates on:
2021­06­28
regarding biodegradation,
ecotoxicity and control of
constituents
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/FDIS 23517:2021(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 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23517:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 23517:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Basic requirements ............................................................................................................................................................................................ 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Control of constituents ..................................................................................................................................................................... 3

4.3 Ultimate aerobic biodegradation ............................................................................................................................................ 4

4.4 Negative effects on terrestrial organism........................................................................................................................... 4

5 Detailed requirements ................................................................................................................................................................................... 4

5.1 Control of constituents ..................................................................................................................................................................... 4

5.1.1 Regulated metals and other elements ........................................................................................................... 4

5.1.2 Organic and inorganic fluorine ............................................................................................................................ 4

5.1.3 Other hazardous substances ................................................................................................................................. 4

5.1.4 Volatile solids ...................................................................................................................................................................... 4

5.2 Ultimate aerobic biodegradation ............................................................................................................................................ 5

5.2.1 Test method and evaluation criteria ............................................................................................................... 5

5.2.2 Requirements regarding constituents ........................................................................................................... 5

5.3 Negative effects on terrestrial organism........................................................................................................................... 6

5.3.1 Ecotoxicity testing scheme ...................................................................................................................................... 6

5.3.2 Preparation of soils for ecotoxicity tests ..................................................................................................... 6

5.3.3 Acute toxicity plant growth test .......................................................................................................................... 7

5.3.4 Earthworm test ................................................................................................................................................................. 7

5.3.5 Nitrification inhibition test with soil microorganisms ................................................................... 8

6 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Examples of maximum concentrations of regulated metals and other

elements .....................................................................................................................................................................................................................10

Annex B (normative) Maximum concentrations of organic and inorganic fluorine and other

hazardous substances ..................................................................................................................................................................................11

Annex C (normative) Determination of acute effects of materials on the emergence and

growth of higher plants ..............................................................................................................................................................................13

Annex D (normative) Determination of acute effects of materials on earthworms .........................................15

Annex E (normative) Determination of effects on reproduction of earthworms................................................16

Annex F (normative) Determination of nitrification of soil microorganisms ........................................................17

Annex G (normative) Preparation of soils for ecotoxicity testing .......................................................................................18

Annex H (informative) Visual surface evaluation method of the disintegration in a slide

frame test ..................................................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................24

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23517:2021(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 61, Plastics, Subcommittee SC 14,

Environmental aspects.

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 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23517:2021(E)
Introduction

Biodegradable mulch films are used worldwide in agriculture and horticulture for many years. They

enhance growing conditions and contribute to increased yields and improved crop quality by, for

example:
— inhibiting the development of weeds;
— reducing significantly the consumption of water and other resources;
— control of soil temperature;
— reduction in leaching of mineral elements and other fertilizer;
— reduction in soil compaction;
— protecting the crops from soil.

Biodegradable mulch films are not designed to be recovered from soil at the end of the intended service

life. Therefore, it is no longer necessary for farmers to retrieve the biodegradable mulch film from the

field for disposal or recycling after the harvest. Farmers can simply plow it under along with what

remains from the plants so that it is incorporated into soil.

This document defines the standard specification to be met for biodegradable mulch films to be

used in agriculture and horticulture. It is suited to characterize both the plastic materials which are

used to manufacture mulch films and the mulch films itself with respect to characteristics such as

biodegradation, adverse effects on terrestrial organisms and control of constituents.

© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23517:2021(E)
Plastics — Soil biodegradable materials for mulch films for
use in agriculture and horticulture — Requirements and
test methods regarding biodegradation, ecotoxicity and
control of constituents
1 Scope

This document is applicable to biodegradable plastic materials used to produce mulch films or

biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture.

This document specifies test methods and evaluation criteria by addressing the following

characteristics:
a) control of constituents;
b) biodegradation;
c) negative effects on terrestrial organisms.

NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic

products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

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 10390, Soil quality — Determination of pH

ISO 11268­1, Soil quality — Effects of pollutants on earthworms — Part 1: Determination of acute toxicity

to Eisenia fetida/Eisenia andrei

ISO 11268­2, Soil quality — Effects of pollutants on earthworms — Part 2: Determination of effects on

reproduction of Eisenia fetida/Eisenia andrei

ISO 11269­2, Soil quality — Determination of the effects of pollutants on soil flora — Part 2: Effects of

contaminated soil on the emergence and early growth of higher plants

ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods

EN 14582, Characterization of waste — Halogen and sulfur content — Oxygen combustion in closed

systems and determination methods

ISO 15685, Soil quality — Determination of potential nitrification and inhibition of nitrification — Rapid

test by ammonium oxidation

ISO 17556, Plastics — Determination of the ultimate aerobic biodegradability of plastic materials in soil by

measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

OECD. (2006), Test No. 208: Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, OECD

Guidelines for the Testing of Chemicals, Section 2
© ISO 2021 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/FDIS 23517:2021(E)
3 Terms and definitions
For 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.el ectropedia. org/
3.1
mulch film

film made from thermoplastic material intended to be used in agriculture and horticulture to cover the

ground in order to improve growing conditions of crops and depending on the colour to control weeds

Note 1 to entry: It is assumed that a transparent mulch film does not allow to control weeds.

[SOURCE: EN 17033:2018, 3.1.1]
3.2
material

homogenous preparation of biodegradable polymer and additives, as necessary, such as carbon black

and colour pigments

Note 1 to entry: Additives are usually introduced under the form of masterbatches using as carrier resin a

biodegradable polymer.
[SOURCE: EN 17033:2018, 3.1.2]
3.3
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

[SOURCE: ISO 17088:2021, 3.9]
3.4
mineralization

decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides,

oxides or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]
3.5
disintegration
physical breakdown of a material into fragments
[SOURCE: ISO 18606:2013, 3.3]
3.6
degradation

irreversible process leading to a significant change in the structure of a material, typically characterized

by a change of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by

fragmentation, affected by environmental conditions, proceeding over a period of time and comprising

one or more steps
[SOURCE: ISO 472:2013, 2.262]
2 © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/FDIS 23517:2021(E)
3.7
total dry solid

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
[SOURCE: ISO 17088:2021, 3.8]
3.8
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids (3.7) of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

[SOURCE: ISO 17088:2021, 3.10]
3.9
organic constituent

chemical constituent that contains carbon covalently linked to other carbon atoms and to other

elements, most commonly hydrogen, oxygen or nitrogen

Note 1 to entry: Inorganic carbonates, carbides, cyanides and simple oxides such as carbon monoxide and carbon

dioxide are not considered as organic constituent.

Note 2 to entry: Allotropes of carbon, such as diamond, graphite, carbon black, fullerenes, and carbon nanotubes

are also not considered as organic constituent.
[SOURCE: ISO 17088:2021, 3.15]
3.10
natural soil
soil collected from the surface layer of fields and/or forests
[SOURCE: EN 17033:2018, 3.3.1]
3.11
poly- and perfluoroalkyl substances
PFAS

organofluorine compounds containing only carbon-fluorine bonds and carbon-carbon bonds but also

other heteroatoms
4 Basic requirements
4.1 General

In order to be identified as a biodegradable mulch film in accordance with this document, the mulch film

or the material of the mulch film under investigation shall fulfil all requirements specified in Clause 4

and Clause 5, respectively.
If not all requirements are met, no reference to this document shall be made.
4.2 Control of constituents

The mulch film or the material of the mulch film shall be identified and characterized prior to testing

including:
— determination of the presence of regulated metals and other elements;

— determination of the presence of organic [poly- and perfluoroalkyl substances (PFAS)] and inorganic

fluorine (determined as fluorine);
© ISO 2021 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO/FDIS 23517:2021(E)

— evaluation of the presence of other hazardous substance as specified in Annex B;

taking legal compliance into consideration.
In addition, volatile solids shall be determined.
4.3 Ultimate aerobic biodegradation

The ultimate level of aerobic biodegradation shall be established by testing under controlled conditions

as laid down in 5.2.1.
4.4 Negative effects on terrestrial organism

The mulch film or the material of the mulch film shall have no adverse effects on terrestrial organisms.

5 Detailed requirements
5.1 Control of constituents
5.1.1 Regulated metals and other elements

The concentrations of regulated metals and other elements in a mulch film or material of the mulch film

shall be less than 50 % of those prescribed for sludges, fertilizers and composts in the country where

the final product will be placed on the market or disposed of (see Annex A for examples).

Regulated metals and other elements shall be determined and reported.
5.1.2 Organic and inorganic fluorine
5.1.2.1 Organic fluorine (PFAS)

From a precautionary perspective, poly- and perfluoroalkyl substances (PFAS) shall not be intentionally

added to the mulch film or to a material of the mulch film.

NOTE Most of poly- and perfluoroalkyl substances (PFAS) are extremely persistent in the environment and

in addition, certain PFAS are suspected to have bioaccumulative properties and adverse effects for environment

and human health.
5.1.2.2 Inorganic fluorine

The concentration of inorganic fluorine in the mulch film or in a material of the mulch film shall be less

than 100 mg fluorine/kg material (dry matter) (see Annex B).
5.1.3 Other hazardous substances

From a precautionary perspective, hazardous substances as specified in Annex B shall not be

intentionally added to a mulch film or material of the mulch film.

Information on the use of hazardous substances shall be recorded and can be based on a self­declaration.

5.1.4 Volatile solids

A mulch film or material of a mulch film shall contain a minimum of 60 % of volatile solids.

Volatile solids shall be determined and reported.
4 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
5.2 Ultimate aerobic biodegradation
5.2.1 Test method and evaluation criteria

The ultimate aerobic biodegradability shall be determined for the whole material or for each organic

constituent.

Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or

an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to

ISO 17556.

The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil

if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as

specified hereunder:

a) 90 % of the organic carbon shall have been converted to CO by the end of the test period (relative

to a reference material). Both the reference material and the test item shall be tested for the same

length of time and the results compared at the same point in time;

b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to

carbon dioxide by the end of the test period.

If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then

the biodegradation test can be terminated. However, the test period shall be no longer than 2 years.

The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range

between 20 °C and 28 °C, preferably 25 °C.

Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder

or ashless cellulose filters). If possible, the physical form and size of the reference material should be

comparable to that of the test material.
The validity criteria as stated in ISO 17556 shall be fulfilled.

NOTE Biodegradability is assessed by measuring the mineralization level, i.e. the conversion of the organic

carbon of a product or a material into CO with the consumption of O under aerobic conditions, or into CO

2 2 2

and CH under anaerobic conditions. During biodegradation, part of the organic carbon is also assimilated as

biomass. This biomass yield typically ranges from 10 % to 40 %, depending on the substrate. As a consequence,

the mineralization level rarely reaches 100 % also when the biodegradation is 100 %, because of biomass

formation. Standard test methods for the accurate determination of product´s or material’s carbon assimilated in

biomass during biodegradation are not available yet.
5.2.2 Requirements regarding constituents

Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to

demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass).

For organic constituents which are present in the material at a concentration between 1 % and 15 % (by

dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in

5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to

be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301,

[30] [31]

Methods A to F ; OECD 310 ) are considered as biodegradable in the context of ISO 23517.

As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass),

the level of biodegradation of that organic constituent can be determined using an artificial blend of the

same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial

blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to

be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a

material on the condition that the co-substrate is present as tested in the artificial blend.

© ISO 2021 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/FDIS 23517:2021(E)

Carbon black which is frequently used in mulch film is an inert solid. Therefore, it is not considered as

an organic constituent and shall not be accounted in the calculation of the degree of biodegradation.

NOTE The objective of testing an artificial blend is to demonstrate that a constituent which does not meet

the biodegradability requirements of ISO 23517 when tested alone, may become biodegradable in combination

with another biodegradable constituents of a material. The concentration of the constituent in the artificial

blend was set at a minimum of 15 % in order to avoid false-positive results, as theoretically a material with, for

example, 10 % of a non or moderately biodegradable constituent may still reach the pass level for biodegradation

specified in 5.2.1.
5.3 Negative effects on terrestrial organism
5.3.1 Ecotoxicity testing scheme

Ecotoxicity tests shall be performed in order to investigate possible adverse effects caused by

degradation products resulting from the degradation of the material of a mulch film in soil at the end of

the intended service life.
The test scheme takes into account:

— all relevant terrestrial organism groups as plants, earthworms (invertebrates) and microorganisms;

— important ecological processes critical due to their role in maintaining soil functions as breakdown

of organic matter, formulation of soil structure and cycling of materials;

— all relevant exposure pathways as soil pore water, soil pore air and soil material.

The link between soil organism groups of major ecological importance covering all significant soil

exposure pathways and suitable test methods for the evaluation of ecotoxicity of the materials of mulch

films and their degradation products is shown in Table 1.
Table 1 — Test scheme for the assessment of ecotoxicity
Organism group Ecological process Soil exposure pathway Test methods
plant growth test according to
plants: mainly soil pore water
primary production OECD 208 or ISO 11269­2 with the
­ higher plants (by root uptake)
modifications specified in Annex C
diverse and multiple up­
take routes: acute earthworm test according to
ISO 11268-1 with the modifications
breakdown of organic ­ soil pore water;
invertebrates:
specified in Annex D or alternative­
matter; formation of
­ ingestion of soil ly chronic earthworm toxicity test
­ earthworms
soil structure
according to ISO 11268­2 with the
material;
modifications laid down in Annex E
­ soil air
nitrification inhibition test with
microorganisms:
soil microorganisms according to
recycling of nutrients mainly soil pore water
ISO 15685 with the modifications
­ bacteria
specified in Annex F

Ecotoxic effects on terrestrial organism shall be determined by comparing soils produced with or

without the addition of a test material.
5.3.2 Preparation of soils for ecotoxicity tests

The ecotoxicity of degradation products shall be evaluated according to the test methods specified in

5.3.3, 5.3.4 and 5.3.5 using test soils prepared according to Annex G.
6 © ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/FDIS 23517:2021(E)

The initial test item concentration in the reactor with test material shall be 1 % dry weight.

NOTE Rationale for an initial test item concentration of 1 %: a 1 % loading is much higher than the expected

application loading of a biodegradable mulch film on soil. For example: a typical mulch film is 1,5 × 10 m thick

­3 −2 ­2

and has a density of 1 250 kg m . This means 1,875 × 10 kg m for one application. The soil depth where

a mulch film is typically used or remains after use is presumed to be 0,20 m, in agreement with the normal

2 2

depth of soil tillage. Therefore, 1 m of mulch film covering 1 m of soil surface will typically be mixed with a

volume of soil equal to 0,2 m . This amount of soil weighs approximately 300 kg, considering a soil bulk density

of 1 500 kg m . Therefore, the typical loading of the mulch film in normal use will be approximately 0,006 3 %

(1,875 × 10 kg/300 kg × 100) which is far below the initial test item concentration of 1 % taking into account

also various film thickness and repeated applications.
5.3.3 Acute toxicity plant growth test

The purpose of this test is to determine the possible toxic effects of mulch films incorporated in soil

on the emergence, the early stages of growth and development of terrestrial plants. The basis for the

determination is OECD 208 or, alternatively, ISO 11269-2. The principles of the standard test methods

shall be followed with the modifications given in the Annex C.

The germination rate and the plant biomass of the tested plant species in the soil exposed to the test

material shall be more than 90 % of those from the corresponding blank soil not exposed to the te

...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23517
ISO/TC 61/SC 14
Plastics — Soil biodegradable
Secretariat: DIN
materials for mulch films for use
Voting begins on:
2021­05­03 in agriculture and horticulture —
Requirements and test methods
Voting terminates on:
2021­06­28
regarding biodegradation,
ecotoxicity and control of
constituents
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/FDIS 23517:2021(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 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23517:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 23517:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Basic requirements ............................................................................................................................................................................................ 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Control of constituents ..................................................................................................................................................................... 3

4.3 Ultimate aerobic biodegradation ............................................................................................................................................ 4

4.4 Negative effects on terrestrial organism........................................................................................................................... 4

5 Detailed requirements ................................................................................................................................................................................... 4

5.1 Control of constituents ..................................................................................................................................................................... 4

5.1.1 Regulated metals and other elements ........................................................................................................... 4

5.1.2 Organic and inorganic fluorine ............................................................................................................................ 4

5.1.3 Other hazardous substances ................................................................................................................................. 4

5.1.4 Volatile solids ...................................................................................................................................................................... 4

5.2 Ultimate aerobic biodegradation ............................................................................................................................................ 5

5.2.1 Test method and evaluation criteria ............................................................................................................... 5

5.2.2 Requirements regarding constituents ........................................................................................................... 5

5.3 Negative effects on terrestrial organism........................................................................................................................... 6

5.3.1 Ecotoxicity testing scheme ...................................................................................................................................... 6

5.3.2 Preparation of soils for ecotoxicity tests ..................................................................................................... 6

5.3.3 Acute toxicity plant growth test .......................................................................................................................... 7

5.3.4 Earthworm test ................................................................................................................................................................. 7

5.3.5 Nitrification inhibition test with soil microorganisms ................................................................... 8

6 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Examples of maximum concentrations of regulated metals and other

elements .....................................................................................................................................................................................................................10

Annex B (normative) Maximum concentrations of organic and inorganic fluorine and other

hazardous substances ..................................................................................................................................................................................11

Annex C (normative) Determination of acute effects of materials on the emergence and

growth of higher plants ..............................................................................................................................................................................13

Annex D (normative) Determination of acute effects of materials on earthworms .........................................15

Annex E (normative) Determination of effects on reproduction of earthworms................................................16

Annex F (normative) Determination of nitrification of soil microorganisms ........................................................17

Annex G (normative) Preparation of soils for ecotoxicity testing .......................................................................................18

Annex H (informative) Visual surface evaluation method of the disintegration in a slide

frame test ..................................................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................24

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23517:2021(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 61, Plastics, Subcommittee SC 14,

Environmental aspects.

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 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23517:2021(E)
Introduction

Biodegradable mulch films are used worldwide in agriculture and horticulture for many years. They

enhance growing conditions and contribute to increased yields and improved crop quality by, for

example:
— inhibiting the development of weeds;
— reducing significantly the consumption of water and other resources;
— control of soil temperature;
— reduction in leaching of mineral elements and other fertilizer;
— reduction in soil compaction;
— protecting the crops from soil.

Biodegradable mulch films are not designed to be recovered from soil at the end of the intended service

life. Therefore, it is no longer necessary for farmers to retrieve the biodegradable mulch film from the

field for disposal or recycling after the harvest. Farmers can simply plow it under along with what

remains from the plants so that it is incorporated into soil.

This document defines the standard specification to be met for biodegradable mulch films to be

used in agriculture and horticulture. It is suited to characterize both the plastic materials which are

used to manufacture mulch films and the mulch films itself with respect to characteristics such as

biodegradation, adverse effects on terrestrial organisms and control of constituents.

© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23517:2021(E)
Plastics — Soil biodegradable materials for mulch films for
use in agriculture and horticulture — Requirements and
test methods regarding biodegradation, ecotoxicity and
control of constituents
1 Scope

This document is applicable to biodegradable plastic materials used to produce mulch films or

biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture.

This document specifies test methods and evaluation criteria by addressing the following

characteristics:
a) control of constituents;
b) biodegradation;
c) negative effects on terrestrial organisms.

NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic

products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

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 10390, Soil quality — Determination of pH

ISO 11268­1, Soil quality — Effects of pollutants on earthworms — Part 1: Determination of acute toxicity

to Eisenia fetida/Eisenia andrei

ISO 11268­2, Soil quality — Effects of pollutants on earthworms — Part 2: Determination of effects on

reproduction of Eisenia fetida/Eisenia andrei

ISO 11269­2, Soil quality — Determination of the effects of pollutants on soil flora — Part 2: Effects of

contaminated soil on the emergence and early growth of higher plants

ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods

EN 14582, Characterization of waste — Halogen and sulfur content — Oxygen combustion in closed

systems and determination methods

ISO 15685, Soil quality — Determination of potential nitrification and inhibition of nitrification — Rapid

test by ammonium oxidation

ISO 17556, Plastics — Determination of the ultimate aerobic biodegradability of plastic materials in soil by

measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

OECD. (2006), Test No. 208: Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, OECD

Guidelines for the Testing of Chemicals, Section 2
© ISO 2021 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/FDIS 23517:2021(E)
3 Terms and definitions
For 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.el ectropedia. org/
3.1
mulch film

film made from thermoplastic material intended to be used in agriculture and horticulture to cover the

ground in order to improve growing conditions of crops and depending on the colour to control weeds

Note 1 to entry: It is assumed that a transparent mulch film does not allow to control weeds.

[SOURCE: EN 17033:2018, 3.1.1]
3.2
material

homogenous preparation of biodegradable polymer and additives, as necessary, such as carbon black

and colour pigments

Note 1 to entry: Additives are usually introduced under the form of masterbatches using as carrier resin a

biodegradable polymer.
[SOURCE: EN 17033:2018, 3.1.2]
3.3
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

[SOURCE: ISO 17088:2021, 3.9]
3.4
mineralization

decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides,

oxides or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]
3.5
disintegration
physical breakdown of a material into fragments
[SOURCE: ISO 18606:2013, 3.3]
3.6
degradation

irreversible process leading to a significant change in the structure of a material, typically characterized

by a change of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by

fragmentation, affected by environmental conditions, proceeding over a period of time and comprising

one or more steps
[SOURCE: ISO 472:2013, 2.262]
2 © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/FDIS 23517:2021(E)
3.7
total dry solid

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
[SOURCE: ISO 17088:2021, 3.8]
3.8
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids (3.7) of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

[SOURCE: ISO 17088:2021, 3.10]
3.9
organic constituent

chemical constituent that contains carbon covalently linked to other carbon atoms and to other

elements, most commonly hydrogen, oxygen or nitrogen

Note 1 to entry: Inorganic carbonates, carbides, cyanides and simple oxides such as carbon monoxide and carbon

dioxide are not considered as organic constituent.

Note 2 to entry: Allotropes of carbon, such as diamond, graphite, carbon black, fullerenes, and carbon nanotubes

are also not considered as organic constituent.
[SOURCE: ISO 17088:2021, 3.15]
3.10
natural soil
soil collected from the surface layer of fields and/or forests
[SOURCE: EN 17033:2018, 3.3.1]
3.11
poly- and perfluoroalkyl substances
PFAS

organofluorine compounds containing only carbon-fluorine bonds and carbon-carbon bonds but also

other heteroatoms
4 Basic requirements
4.1 General

In order to be identified as a biodegradable mulch film in accordance with this document, the mulch film

or the material of the mulch film under investigation shall fulfil all requirements specified in Clause 4

and Clause 5, respectively.
If not all requirements are met, no reference to this document shall be made.
4.2 Control of constituents

The mulch film or the material of the mulch film shall be identified and characterized prior to testing

including:
— determination of the presence of regulated metals and other elements;

— determination of the presence of organic [poly- and perfluoroalkyl substances (PFAS)] and inorganic

fluorine (determined as fluorine);
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ISO/FDIS 23517:2021(E)

— evaluation of the presence of other hazardous substance as specified in Annex B;

taking legal compliance into consideration.
In addition, volatile solids shall be determined.
4.3 Ultimate aerobic biodegradation

The ultimate level of aerobic biodegradation shall be established by testing under controlled conditions

as laid down in 5.2.1.
4.4 Negative effects on terrestrial organism

The mulch film or the material of the mulch film shall have no adverse effects on terrestrial organisms.

5 Detailed requirements
5.1 Control of constituents
5.1.1 Regulated metals and other elements

The concentrations of regulated metals and other elements in a mulch film or material of the mulch film

shall be less than 50 % of those prescribed for sludges, fertilizers and composts in the country where

the final product will be placed on the market or disposed of (see Annex A for examples).

Regulated metals and other elements shall be determined and reported.
5.1.2 Organic and inorganic fluorine
5.1.2.1 Organic fluorine (PFAS)

From a precautionary perspective, poly- and perfluoroalkyl substances (PFAS) shall not be intentionally

added to the mulch film or to a material of the mulch film.

NOTE Most of poly- and perfluoroalkyl substances (PFAS) are extremely persistent in the environment and

in addition, certain PFAS are suspected to have bioaccumulative properties and adverse effects for environment

and human health.
5.1.2.2 Inorganic fluorine

The concentration of inorganic fluorine in the mulch film or in a material of the mulch film shall be less

than 100 mg fluorine/kg material (dry matter) (see Annex B).
5.1.3 Other hazardous substances

From a precautionary perspective, hazardous substances as specified in Annex B shall not be

intentionally added to a mulch film or material of the mulch film.

Information on the use of hazardous substances shall be recorded and can be based on a self­declaration.

5.1.4 Volatile solids

A mulch film or material of a mulch film shall contain a minimum of 60 % of volatile solids.

Volatile solids shall be determined and reported.
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ISO/FDIS 23517:2021(E)
5.2 Ultimate aerobic biodegradation
5.2.1 Test method and evaluation criteria

The ultimate aerobic biodegradability shall be determined for the whole material or for each organic

constituent.

Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or

an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to

ISO 17556.

The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil

if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as

specified hereunder:

a) 90 % of the organic carbon shall have been converted to CO by the end of the test period (relative

to a reference material). Both the reference material and the test item shall be tested for the same

length of time and the results compared at the same point in time;

b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to

carbon dioxide by the end of the test period.

If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then

the biodegradation test can be terminated. However, the test period shall be no longer than 2 years.

The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range

between 20 °C and 28 °C, preferably 25 °C.

Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder

or ashless cellulose filters). If possible, the physical form and size of the reference material should be

comparable to that of the test material.
The validity criteria as stated in ISO 17556 shall be fulfilled.

NOTE Biodegradability is assessed by measuring the mineralization level, i.e. the conversion of the organic

carbon of a product or a material into CO with the consumption of O under aerobic conditions, or into CO

2 2 2

and CH under anaerobic conditions. During biodegradation, part of the organic carbon is also assimilated as

biomass. This biomass yield typically ranges from 10 % to 40 %, depending on the substrate. As a consequence,

the mineralization level rarely reaches 100 % also when the biodegradation is 100 %, because of biomass

formation. Standard test methods for the accurate determination of product´s or material’s carbon assimilated in

biomass during biodegradation are not available yet.
5.2.2 Requirements regarding constituents

Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to

demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass).

For organic constituents which are present in the material at a concentration between 1 % and 15 % (by

dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in

5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to

be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301,

[30] [31]

Methods A to F ; OECD 310 ) are considered as biodegradable in the context of ISO 23517.

As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass),

the level of biodegradation of that organic constituent can be determined using an artificial blend of the

same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial

blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to

be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a

material on the condition that the co-substrate is present as tested in the artificial blend.

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ISO/FDIS 23517:2021(E)

Carbon black which is frequently used in mulch film is an inert solid. Therefore, it is not considered as

an organic constituent and shall not be accounted in the calculation of the degree of biodegradation.

NOTE The objective of testing an artificial blend is to demonstrate that a constituent which does not meet

the biodegradability requirements of ISO 23517 when tested alone, may become biodegradable in combination

with another biodegradable constituents of a material. The concentration of the constituent in the artificial

blend was set at a minimum of 15 % in order to avoid false-positive results, as theoretically a material with, for

example, 10 % of a non or moderately biodegradable constituent may still reach the pass level for biodegradation

specified in 5.2.1.
5.3 Negative effects on terrestrial organism
5.3.1 Ecotoxicity testing scheme

Ecotoxicity tests shall be performed in order to investigate possible adverse effects caused by

degradation products resulting from the degradation of the material of a mulch film in soil at the end of

the intended service life.
The test scheme takes into account:

— all relevant terrestrial organism groups as plants, earthworms (invertebrates) and microorganisms;

— important ecological processes critical due to their role in maintaining soil functions as breakdown

of organic matter, formulation of soil structure and cycling of materials;

— all relevant exposure pathways as soil pore water, soil pore air and soil material.

The link between soil organism groups of major ecological importance covering all significant soil

exposure pathways and suitable test methods for the evaluation of ecotoxicity of the materials of mulch

films and their degradation products is shown in Table 1.
Table 1 — Test scheme for the assessment of ecotoxicity
Organism group Ecological process Soil exposure pathway Test methods
plant growth test according to
plants: mainly soil pore water
primary production OECD 208 or ISO 11269­2 with the
­ higher plants (by root uptake)
modifications specified in Annex C
diverse and multiple up­
take routes: acute earthworm test according to
ISO 11268-1 with the modifications
breakdown of organic ­ soil pore water;
invertebrates:
specified in Annex D or alternative­
matter; formation of
­ ingestion of soil ly chronic earthworm toxicity test
­ earthworms
soil structure
according to ISO 11268­2 with the
material;
modifications laid down in Annex E
­ soil air
nitrification inhibition test with
microorganisms:
soil microorganisms according to
recycling of nutrients mainly soil pore water
ISO 15685 with the modifications
­ bacteria
specified in Annex F

Ecotoxic effects on terrestrial organism shall be determined by comparing soils produced with or

without the addition of a test material.
5.3.2 Preparation of soils for ecotoxicity tests

The ecotoxicity of degradation products shall be evaluated according to the test methods specified in

5.3.3, 5.3.4 and 5.3.5 using test soils prepared according to Annex G.
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ISO/FDIS 23517:2021(E)

The initial test item concentration in the reactor with test material shall be 1 % dry weight.

NOTE Rationale for an initial test item concentration of 1 %: a 1 % loading is much higher than the expected

application loading of a biodegradable mulch film on soil. For example: a typical mulch film is 1,5 × 10 m thick

­3 −2 ­2

and has a density of 1 250 kg m . This means 1,875 × 10 kg m for one application. The soil depth where

a mulch film is typically used or remains after use is presumed to be 0,20 m, in agreement with the normal

2 2

depth of soil tillage. Therefore, 1 m of mulch film covering 1 m of soil surface will typically be mixed with a

volume of soil equal to 0,2 m . This amount of soil weighs approximately 300 kg, considering a soil bulk density

of 1 500 kg m . Therefore, the typical loading of the mulch film in normal use will be approximately 0,006 3 %

(1,875 × 10 kg/300 kg × 100) which is far below the initial test item concentration of 1 % taking into account

also various film thickness and repeated applications.
5.3.3 Acute toxicity plant growth test

The purpose of this test is to determine the possible toxic effects of mulch films incorporated in soil

on the emergence, the early stages of growth and development of terrestrial plants. The basis for the

determination is OECD 208 or, alternatively, ISO 11269-2. The principles of the standard test methods

shall be followed with the modifications given in the Annex C.

The germination rate and the plant biomass of the tested plant species in the soil exposed to the test

material shall be more than 90 % of those from the corresponding blank soil not exposed to the te

...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23517
ISO/TC 61/SC 14
Plastics — Soil biodegradable
Secretariat: DIN
materials for mulch films for use
Voting begins on:
2021­05­03 in agriculture and horticulture —
Requirements and test methods
Voting terminates on:
2021­06­28
regarding biodegradation,
ecotoxicity and control of
constituents
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/FDIS 23517:2021(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 2021
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ISO/FDIS 23517:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Basic requirements ............................................................................................................................................................................................ 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Control of constituents ..................................................................................................................................................................... 3

4.3 Ultimate aerobic biodegradation ............................................................................................................................................ 4

4.4 Negative effects on terrestrial organism........................................................................................................................... 4

5 Detailed requirements ................................................................................................................................................................................... 4

5.1 Control of constituents ..................................................................................................................................................................... 4

5.1.1 Regulated metals and other elements ........................................................................................................... 4

5.1.2 Organic and inorganic fluorine ............................................................................................................................ 4

5.1.3 Other hazardous substances ................................................................................................................................. 4

5.1.4 Volatile solids ...................................................................................................................................................................... 4

5.2 Ultimate aerobic biodegradation ............................................................................................................................................ 5

5.2.1 Test method and evaluation criteria ............................................................................................................... 5

5.2.2 Requirements regarding constituents ........................................................................................................... 5

5.3 Negative effects on terrestrial organism........................................................................................................................... 6

5.3.1 Ecotoxicity testing scheme ...................................................................................................................................... 6

5.3.2 Preparation of soils for ecotoxicity tests ..................................................................................................... 6

5.3.3 Acute toxicity plant growth test .......................................................................................................................... 7

5.3.4 Earthworm test ................................................................................................................................................................. 7

5.3.5 Nitrification inhibition test with soil microorganisms ................................................................... 8

6 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Examples of maximum concentrations of regulated metals and other

elements .....................................................................................................................................................................................................................10

Annex B (normative) Maximum concentrations of organic and inorganic fluorine and other

hazardous substances ..................................................................................................................................................................................11

Annex C (normative) Determination of acute effects of materials on the emergence and

growth of higher plants ..............................................................................................................................................................................13

Annex D (normative) Determination of acute effects of materials on earthworms .........................................15

Annex E (normative) Determination of effects on reproduction of earthworms................................................16

Annex F (normative) Determination of nitrification of soil microorganisms ........................................................17

Annex G (normative) Preparation of soils for ecotoxicity testing .......................................................................................18

Annex H (informative) Visual surface evaluation method of the disintegration in a slide

frame test ..................................................................................................................................................................................................................20

Bibliography .............................................................................................................................................................................................................................24

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ISO/FDIS 23517:2021(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 61, Plastics, Subcommittee SC 14,

Environmental aspects.

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 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
Introduction

Biodegradable mulch films are used worldwide in agriculture and horticulture for many years. They

enhance growing conditions and contribute to increased yields and improved crop quality by, for

example:
— inhibiting the development of weeds;
— reducing significantly the consumption of water and other resources;
— control of soil temperature;
— reduction in leaching of mineral elements and other fertilizer;
— reduction in soil compaction;
— protecting the crops from soil.

Biodegradable mulch films are not designed to be recovered from soil at the end of the intended service

life. Therefore, it is no longer necessary for farmers to retrieve the biodegradable mulch film from the

field for disposal or recycling after the harvest. Farmers can simply plow it under along with what

remains from the plants so that it is incorporated into soil.

This document defines the standard specification to be met for biodegradable mulch films to be

used in agriculture and horticulture. It is suited to characterize both the plastic materials which are

used to manufacture mulch films and the mulch films itself with respect to characteristics such as

biodegradation, adverse effects on terrestrial organisms and control of constituents.

© ISO 2021 – All rights reserved v
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23517:2021(E)
Plastics — Soil biodegradable materials for mulch films for
use in agriculture and horticulture — Requirements and
test methods regarding biodegradation, ecotoxicity and
control of constituents
1 Scope

This document is applicable to biodegradable plastic materials used to produce mulch films or

biodegradable mulch films ready to be used for mulch applications in agriculture and horticulture.

This document specifies test methods and evaluation criteria by addressing the following

characteristics:
a) control of constituents;
b) biodegradation;
c) negative effects on terrestrial organisms.

NOTE This document is construed in a way that it can be used to assess other soil biodegradable plastic

products that do not qualify as mulch films. For example: drip tape, twine, clips, and plant pots.

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 10390, Soil quality — Determination of pH

ISO 11268­1, Soil quality — Effects of pollutants on earthworms — Part 1: Determination of acute toxicity

to Eisenia fetida/Eisenia andrei

ISO 11268­2, Soil quality — Effects of pollutants on earthworms — Part 2: Determination of effects on

reproduction of Eisenia fetida/Eisenia andrei

ISO 11269­2, Soil quality — Determination of the effects of pollutants on soil flora — Part 2: Effects of

contaminated soil on the emergence and early growth of higher plants

ISO 11274, Soil quality — Determination of the water-retention characteristic — Laboratory methods

EN 14582, Characterization of waste — Halogen and sulfur content — Oxygen combustion in closed

systems and determination methods

ISO 15685, Soil quality — Determination of potential nitrification and inhibition of nitrification — Rapid

test by ammonium oxidation

ISO 17556, Plastics — Determination of the ultimate aerobic biodegradability of plastic materials in soil by

measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

OECD. (2006), Test No. 208: Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test, OECD

Guidelines for the Testing of Chemicals, Section 2
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ISO/FDIS 23517:2021(E)
3 Terms and definitions
For 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.el ectropedia. org/
3.1
mulch film

film made from thermoplastic material intended to be used in agriculture and horticulture to cover the

ground in order to improve growing conditions of crops and depending on the colour to control weeds

Note 1 to entry: It is assumed that a transparent mulch film does not allow to control weeds.

[SOURCE: EN 17033:2018, 3.1.1]
3.2
material

homogenous preparation of biodegradable polymer and additives, as necessary, such as carbon black

and colour pigments

Note 1 to entry: Additives are usually introduced under the form of masterbatches using as carrier resin a

biodegradable polymer.
[SOURCE: EN 17033:2018, 3.1.2]
3.3
ultimate aerobic biodegradation

breakdown of an organic compound by microorganisms in the presence of oxygen into carbon dioxide,

water and mineral salts of any other elements present (mineralization) plus new biomass

[SOURCE: ISO 17088:2021, 3.9]
3.4
mineralization

decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides,

oxides or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]
3.5
disintegration
physical breakdown of a material into fragments
[SOURCE: ISO 18606:2013, 3.3]
3.6
degradation

irreversible process leading to a significant change in the structure of a material, typically characterized

by a change of properties (e.g. integrity, molecular mass or structure, mechanical strength) and/or by

fragmentation, affected by environmental conditions, proceeding over a period of time and comprising

one or more steps
[SOURCE: ISO 472:2013, 2.262]
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ISO/FDIS 23517:2021(E)
3.7
total dry solid

amount of solids obtained by taking a known volume of test material or compost and drying at about

105 °C to constant mass
[SOURCE: ISO 17088:2021, 3.8]
3.8
volatile solids

amount of solids obtained by subtracting the residue of a known volume of test material or compost

after incineration at about 550 °C from the total dry solids (3.7) of the same sample

Note 1 to entry: The volatile-solids content is an indication of the amount of organic matter present.

[SOURCE: ISO 17088:2021, 3.10]
3.9
organic constituent

chemical constituent that contains carbon covalently linked to other carbon atoms and to other

elements, most commonly hydrogen, oxygen or nitrogen

Note 1 to entry: Inorganic carbonates, carbides, cyanides and simple oxides such as carbon monoxide and carbon

dioxide are not considered as organic constituent.

Note 2 to entry: Allotropes of carbon, such as diamond, graphite, carbon black, fullerenes, and carbon nanotubes

are also not considered as organic constituent.
[SOURCE: ISO 17088:2021, 3.15]
3.10
natural soil
soil collected from the surface layer of fields and/or forests
[SOURCE: EN 17033:2018, 3.3.1]
3.11
poly- and perfluoroalkyl substances
PFAS

organofluorine compounds containing only carbon-fluorine bonds and carbon-carbon bonds but also

other heteroatoms
4 Basic requirements
4.1 General

In order to be identified as a biodegradable mulch film in accordance with this document, the mulch film

or the material of the mulch film under investigation shall fulfil all requirements specified in Clause 4

and Clause 5, respectively.
If not all requirements are met, no reference to this document shall be made.
4.2 Control of constituents

The mulch film or the material of the mulch film shall be identified and characterized prior to testing

including:
— determination of the presence of regulated metals and other elements;

— determination of the presence of organic [poly- and perfluoroalkyl substances (PFAS)] and inorganic

fluorine (determined as fluorine);
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ISO/FDIS 23517:2021(E)

— evaluation of the presence of other hazardous substance as specified in Annex B;

taking legal compliance into consideration.
In addition, volatile solids shall be determined.
4.3 Ultimate aerobic biodegradation

The ultimate level of aerobic biodegradation shall be established by testing under controlled conditions

as laid down in 5.2.1.
4.4 Negative effects on terrestrial organism

The mulch film or the material of the mulch film shall have no adverse effects on terrestrial organisms.

5 Detailed requirements
5.1 Control of constituents
5.1.1 Regulated metals and other elements

The concentrations of regulated metals and other elements in a mulch film or material of the mulch film

shall be less than 50 % of those prescribed for sludges, fertilizers and composts in the country where

the final product will be placed on the market or disposed of (see Annex A for examples).

Regulated metals and other elements shall be determined and reported.
5.1.2 Organic and inorganic fluorine
5.1.2.1 Organic fluorine (PFAS)

From a precautionary perspective, poly- and perfluoroalkyl substances (PFAS) shall not be intentionally

added to the mulch film or to a material of the mulch film.

NOTE Most of poly- and perfluoroalkyl substances (PFAS) are extremely persistent in the environment and

in addition, certain PFAS are suspected to have bioaccumulative properties and adverse effects for environment

and human health.
5.1.2.2 Inorganic fluorine

The concentration of inorganic fluorine in the mulch film or in a material of the mulch film shall be less

than 100 mg fluorine/kg material (dry matter) (see Annex B).
5.1.3 Other hazardous substances

From a precautionary perspective, hazardous substances as specified in Annex B shall not be

intentionally added to a mulch film or material of the mulch film.

Information on the use of hazardous substances shall be recorded and can be based on a self­declaration.

5.1.4 Volatile solids

A mulch film or material of a mulch film shall contain a minimum of 60 % of volatile solids.

Volatile solids shall be determined and reported.
4 © ISO 2021 – All rights reserved
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ISO/FDIS 23517:2021(E)
5.2 Ultimate aerobic biodegradation
5.2.1 Test method and evaluation criteria

The ultimate aerobic biodegradability shall be determined for the whole material or for each organic

constituent.

Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or

an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to

ISO 17556.

The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil

if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as

specified hereunder:

a) 90 % of the organic carbon shall have been converted to CO by the end of the test period (relative

to a reference material). Both the reference material and the test item shall be tested for the same

length of time and the results compared at the same point in time;

b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to

carbon dioxide by the end of the test period.

If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then

the biodegradation test can be terminated. However, the test period shall be no longer than 2 years.

The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range

between 20 °C and 28 °C, preferably 25 °C.

Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder

or ashless cellulose filters). If possible, the physical form and size of the reference material should be

comparable to that of the test material.
The validity criteria as stated in ISO 17556 shall be fulfilled.

NOTE Biodegradability is assessed by measuring the mineralization level, i.e. the conversion of the organic

carbon of a product or a material into CO with the consumption of O under aerobic conditions, or into CO

2 2 2

and CH under anaerobic conditions. During biodegradation, part of the organic carbon is also assimilated as

biomass. This biomass yield typically ranges from 10 % to 40 %, depending on the substrate. As a consequence,

the mineralization level rarely reaches 100 % also when the biodegradation is 100 %, because of biomass

formation. Standard test methods for the accurate determination of product´s or material’s carbon assimilated in

biomass during biodegradation are not available yet.
5.2.2 Requirements regarding constituents

Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to

demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass).

For organic constituents which are present in the material at a concentration between 1 % and 15 % (by

dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in

5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to

be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301,

[30] [31]

Methods A to F ; OECD 310 ) are considered as biodegradable in the context of ISO 23517.

As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass),

the level of biodegradation of that organic constituent can be determined using an artificial blend of the

same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial

blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to

be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a

material on the condition that the co-substrate is present as tested in the artificial blend.

© ISO 2021 – All rights reserved 5
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ISO/FDIS 23517:2021(E)

Carbon black which is frequently used in mulch film is an inert solid. Therefore, it is not considered as

an organic constituent and shall not be accounted in the calculation of the degree of biodegradation.

NOTE The objective of testing an artificial blend is to demonstrate that a constituent which does not meet

the biodegradability requirements of ISO 23517 when tested alone, may become biodegradable in combination

with another biodegradable constituents of a material. The concentration of the constituent in the artificial

blend was set at a minimum of 15 % in order to avoid false-positive results, as theoretically a material with, for

example, 10 % of a non or moderately biodegradable constituent may still reach the pass level for biodegradation

specified in 5.2.1.
5.3 Negative effects on terrestrial organism
5.3.1 Ecotoxicity testing scheme

Ecotoxicity tests shall be performed in order to investigate possible adverse effects caused by

degradation products resulting from the degradation of the material of a mulch film in soil at the end of

the intended service life.
The test scheme takes into account:

— all relevant terrestrial organism groups as plants, earthworms (invertebrates) and microorganisms;

— important ecological processes critical due to their role in maintaining soil functions as breakdown

of organic matter, formulation of soil structure and cycling of materials;

— all relevant exposure pathways as soil pore water, soil pore air and soil material.

The link between soil organism groups of major ecological importance covering all significant soil

exposure pathways and suitable test methods for the evaluation of ecotoxicity of the materials of mulch

films and their degradation products is shown in Table 1.
Table 1 — Test scheme for the assessment of ecotoxicity
Organism group Ecological process Soil exposure pathway Test methods
plant growth test according to
plants: mainly soil pore water
primary production OECD 208 or ISO 11269­2 with the
­ higher plants (by root uptake)
modifications specified in Annex C
diverse and multiple up­
take routes: acute earthworm test according to
ISO 11268-1 with the modifications
breakdown of organic ­ soil pore water;
invertebrates:
specified in Annex D or alternative­
matter; formation of
­ ingestion of soil ly chronic earthworm toxicity test
­ earthworms
soil structure
according to ISO 11268­2 with the
material;
modifications laid down in Annex E
­ soil air
nitrification inhibition test with
microorganisms:
soil microorganisms according to
recycling of nutrients mainly soil pore water
ISO 15685 with the modifications
­ bacteria
specified in Annex F

Ecotoxic effects on terrestrial organism shall be determined by comparing soils produced with or

without the addition of a test material.
5.3.2 Preparation of soils for ecotoxicity tests

The ecotoxicity of degradation products shall be evaluated according to the test methods specified in

5.3.3, 5.3.4 and 5.3.5 using test soils prepared according to Annex G.
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ISO/FDIS 23517:2021(E)

The initial test item concentration in the reactor with test material shall be 1 % dry weight.

NOTE Rationale for an initial test item concentration of 1 %: a 1 % loading is much higher than the expected

application loading of a biodegradable mulch film on soil. For example: a typical mulch film is 1,5 × 10 m thick

­3 −2 ­2

and has a density of 1 250 kg m . This means 1,875 × 10 kg m for one application. The soil depth where

a mulch film is typically used or remains after use is presumed to be 0,20 m, in agreement with the normal

2 2

depth of soil tillage. Therefore, 1 m of mulch film covering 1 m of soil surface will typically be mixed with a

volume of soil equal to 0,2 m . This amount of soil weighs approximately 300 kg, considering a soil bulk density

of 1 500 kg m . Therefore, the typical loading of the mulch film in normal use will be approximately 0,006 3 %

(1,875 × 10 kg/300 kg × 100) which is far below the initial test item concentration of 1 % taking into account

also various film thickness and repeated applications.
5.3.3 Acute toxicity plant growth test

The purpose of this test is to determine the possible toxic effects of mulch films incorporated in soil

on the emergence, the early stages of growth and development of terrestrial plants. The basis for the

determination is OECD 208 or, alternatively, ISO 11269-2. The principles of the standard test methods

shall be followed with the modifications given in the Annex C.

The germination rate and the plant biomass of the tested plant species in the soil exposed to the test

material shall be more than 90 % of those from the corresponding blank soil not exposed to the te

...

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