EN ISO 846:2019

Plastics - Evaluation of the action of microorganisms (ISO 846:2019)

This document specifies methods for determining the deterioration of plastics due to the action of fungi and bacteria and soil microorganisms. The aim is not to determine the biodegradability of plastics or the deterioration of natural fibre composites.
The type and extent of deterioration can be determined by
a)    visual examination and/or
b)    changes in mass and/or
c)    changes in other physical properties.
The tests are applicable to all plastics that have an even surface and that can thus be easily cleaned. The exceptions are porous materials, such as plastic foams.
This document uses the same test fungi as IEC 60068-2-10. The IEC method, which uses so-called "assembled specimens", calls for inoculation of the specimens with a spore suspension, incubation of the inoculated specimens and assessment of the fungal growth as well as any physical attack on the specimens.
The volume of testing and the test strains used depend on the application envisaged for the plastic.

Kunststoffe - Bestimmung der Einwirkung von Mikroorganismen auf Kunststoffe (ISO 846:2019)

Die in diesem Dokument beschriebenen Prüfungen dienen zur Beurteilung des Verhaltens von Kunststoffen gegen Einwirkung bestimmter Pilze und Bakterien sowie der in Erde vorhandenen Mikroorganismen. Das Ziel ist es, nicht die biologische Abbaubarkeit von Kunststoffen oder den Abbau von Naturfaserverbund-werkstoffen zu bestimmen.
Die Art und das Ausmaß der Einwirkung können bestimmt werden:
a)   durch eine visuelle Beurteilung und/oder
b)   Änderung der Masse und/oder
c)   Bestimmung der Änderung anderer physikalischer Eigenschaften.
Diese Prüfungen können auf alle Kunststoffe angewendet werden, die eine allseits geschlossene Oberfläche haben und sich gut reinigen lassen. Ausgeschlossen sind daher poröse Materialien, wie z. B. Schaumstoffe.
Dieses Dokument verwendet die gleichen Prüfpilze wie IEC 60068 2 10. Das IEC Verfahren, bei dem so genannte "zusammengesetzte Prüfkörper" verwendet werden, fordert eine Beimpfung der Prüfkörper mit einer Sporensuspension eines Prüfpilzgemisches, Bebrütung der beimpften Prüfkörper und bewertet den auf¬tretenden Pilzbewuchs ebenso wie mögliche physikalische Eigenschaftsänderungen.
Art und Umfang der vorzunehmenden Prüfungen sowie die zu verwendenden Teststämme hängen von dem vorgesehenen Verwendungszweck der Kunststoffe ab.

Plastiques - Évaluation de l'action des micro-organismes (ISO 846:2019)

Le présent document spécifie des méthodes pour la détermination de la détérioration des plastiques lorsqu'ils sont exposés à l'action des champignons et des bactéries, et à celle des micro-organismes vivant dans le sol. Il n'a pas pour but de déterminer la biodégradabilité des plastiques ou la détérioration des composites en fibres naturelles.
Le type et l'ampleur de la détérioration engendrée peuvent être déterminés:
a)    par un examen visuel; et/ou
b)    à partir des variations de masse; et/ou
c)    à partir des variations d'autres propriétés physiques.
Les essais sont applicables à tous les plastiques ayant une surface plane et qui peuvent, de ce fait, être aisément nettoyés, exception faite des matériaux poreux, tels que les mousses en plastique.
Le présent document utilise les mêmes champignons pour essai que l'IEC 60068‑2‑10. La méthode IEC, qui utilise ce qu'on appelle des «spécimens assemblés», nécessite l'inoculation des éprouvettes avec une suspension de spores, l'incubation des éprouvettes ensemencées et l'évaluation de la croissance fongique ainsi que de l'attaque physique des éprouvettes.
Le volume des essais et les souches d'essai à utiliser dépendront de l'application prévue pour le plastique.

Polimerni materiali - Vrednotenje delovanja mikroorganizmov (ISO 846:2019)

Ta dokument določa metode za ugotavljanje razkroja polimernih materialov zaradi delovanja gliv, bakterij in mikroorganizmov v tleh. Cilj ni ugotavljanje biorazgradljivosti polimernih materialov ali razkroja kompozitov iz naravnih vlaken.
Vrsto in razpon razkroja je mogoče ugotoviti z
a) vizualnim pregledom in/ali
b) spremembo mase in/ali
c) spremembami drugih fizičnih lastnosti.
Preskusi so uporabni za vse polimerne materiale, ki majo enakomerno površino in jih je tako mogoče zlahka čistiti. Izjema so porozni materiali, kot so polimerne pene.
Ta dokument uporablja enake preskusne glive kot standard IEC 60068-2-10. Metoda IEC, ki uporablja tako imenovane »sestavljene primerke«, zahteva inokulacijo primerkov s suspenzijo spor, inkubacijo inokuliranih primerkov ter vrednotenje rasti gliv in morebitnega fizičnega napada na primerke.
Obseg preskušanja in uporabljeni preskusni sevi so odvisni od predvidene uporabe polimernih materialov.

General Information

• Status: Published
• Publication Date: 30-Jul-2019
• Withdrawal Date: 30-Oct-2019
• ICS: 07.100.01 - Microbiology in general
• ICS: 07.100.99 - Other standards related to microbiology
• ICS: 83.080.01 - Plastics in general
• Technical Committee: CEN/TC 249 - Plastics
• Drafting Committee: CEN/TC 249/SC 1/WG 6 - Ageing, chemical and environmental resistance
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 03-Apr-2019
• Completion Date: 03-Apr-2019
• Ref Project: SIST EN ISO 846:2019 - Plastics - Evaluation of the action of microorganisms (ISO 846:2019)

Relations

• Replaces: EN ISO 846:1997 - Plastics - Evaluation of the action of microorganisms (ISO 846:1997)
• Effective Date: 08-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 846:2019
01-junij-2019
1DGRPHãþD
SIST EN ISO 846:1999
Polimerni materiali - Vrednotenje delovanja mikroorganizmov (ISO 846:2019)
Plastics - Evaluation of the action of microorganisms (ISO 846:2019)
Kunststoffe - Bestimmung der Einwirkung von Mikroorganismen auf Kunststoffe (ISO
846:2019)
Plastiques - Évaluation de l'action des micro-organismes (ISO 846:2019)
Ta slovenski standard je istoveten z: EN ISO 846:2019
ICS:
07.100.99 Drugi standardi v zvezi z Other standards related to
mikrobiologijo microbiology
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 846:2019 en,fr,de

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

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SIST EN ISO 846:2019
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SIST EN ISO 846:2019
EN ISO 846
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2019
EUROPÄISCHE NORM
ICS 07.100.99; 83.080.01 Supersedes EN ISO 846:1997
English Version
Plastics - Evaluation of the action of microorganisms (ISO
846:2019)

Plastiques - Évaluation de l'action des micro- Kunststoffe - Bestimmung der Einwirkung von

organismes (ISO 846:2019) Mikroorganismen auf Kunststoffe (ISO 846:2019)
This European Standard was approved by CEN on 5 March 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 846:2019 E

worldwide for CEN national Members.
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SIST EN ISO 846:2019
EN ISO 846:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 846:2019
EN ISO 846:2019 (E)
European foreword

This document (EN ISO 846:2019) has been prepared by Technical Committee ISO/TC 61 "Plastics" in

collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by NBN.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by October 2019, and conflicting national standards shall

be withdrawn at the latest by October 2019.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 846:1997.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 846:2019 has been approved by CEN as EN ISO 846:2019 without any modification.

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SIST EN ISO 846:2019
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SIST EN ISO 846:2019
INTERNATIONAL ISO
STANDARD 846
Third edition
2019-03
Plastics — Evaluation of the action of
microorganisms
Plastiques — Évaluation de l'action des micro-organismes
Reference number
ISO 846:2019(E)
ISO 2019
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SIST EN ISO 846:2019
ISO 846:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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SIST EN ISO 846:2019
ISO 846:2019(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ..............................................................................................................................................................................................................................vii

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

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

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

4.1 General ........................................................................................................................................................................................................... 2

4.2 Resistance to fungi ............................................................................................................................................................................... 2

4.2.1 Method A: Fungal-growth test ............................................................................................................................. 2

4.2.2 Method B: Determination of fungistatic effects .................................................................................... 2

4.3 Method C: Resistance to bacteria ............................................................................................................................................ 3

4.4 Method D: Resistance to microbially active soil (soil-burial test) .............................................................. 3

4.5 Choice of properties for assessment of biodeterioration ................................................................................... 3

5 Apparatus and materials.............................................................................................................................................................................. 3

5.1 For all tests ................................................................................................................................................................................................. 3

5.2 For tests with fungi ......... ..................................................................................................................................................................... 4

5.3 For tests with bacteria ...................................................................................................................................................................... 6

5.4 For soil-burial tests ............................................................................................................................................................................. 6

6 Test specimens........................................................................................................................................................................................................ 7

6.1 Shape and dimensions ...................................................................................................................................................................... 7

6.2 Specimen test series and numbers in each test series.......................................................................................... 7

6.2.1 Specimen test series ..................................................................................................................................................... 7

6.2.2 Numbers in each test series ................................................................................................................................... 8

7 Preparation of specimens ........................................................................................................................................................................... 8

7.1 Cleaning ......................................................................................................................................................................................................... 8

7.2 Labelling and storage ........................................................................................................................................................................ 8

7.3 Conditioning and weighing .......................................................................................................................................................... 8

8 Procedures .................................................................................................................................................................................................................. 9

8.1 Test temperature ................................................................................................................................................................................... 9

8.2 Test methods ............................................................................................................................................................................................. 9

8.2.1 General...................................................................................................................................................................................... 9

8.2.2 Fungal-growth test (method A) .......................................................................................................................... 9

8.2.3 Determination of fungistatic effect (method B) .................................................................................11

8.2.4 Procedure with bacteria (method C) ...........................................................................................................12

8.2.5 Soil-burial test (method D) ..................................................................................................................................13

9 Assessment ..............................................................................................................................................................................................................14

9.1 Assessment of fungal growth on the specimens by visual examination (methods A,

B and D) ......................................................................................................................................................................................................14

9.2 Evaluation of the test specimens for the determination of changes in mass and/or

in other physical properties .....................................................................................................................................................15

9.2.1 Cleaning ................................................................................................................................................................................15

9.2.2 Change in mass ...............................................................................................................................................................15

9.2.3 Determination of changes in other physical properties .............................................................16

10 Expression of results .....................................................................................................................................................................................16

10.1 General ........................................................................................................................................................................................................16

10.2 Visual assessment .............................................................................................................................................................................16

10.3 Change in mass ....................................................................................................................................................................................16

10.4 Changes in other physical properties ...............................................................................................................................16

11 Accuracy of the measurements ..........................................................................................................................................................17

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ISO 846:2019(E)

12 Test report ................................................................................................................................................................................................................17

Annex A (normative) Determination of the water content and water holding capacity of a soil .......19

Annex B (normative) Negative control for Test A .................................................................................................................................21

Annex C (normative) Grid for evaluation of fungal surface growth (Test A) ...........................................................22

Annex D (informative) Information on test fungi .................................................................................................................................24

Bibliography .............................................................................................................................................................................................................................26

iv © ISO 2019 – All rights reserved
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SIST EN ISO 846:2019
ISO 846:2019(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 on 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 the following

URL: www .iso .org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 6, Ageing,

chemical and environmental resistance.

This third edition cancels and replaces the second edition (ISO 846:1997), which has been technically

revised. The main changes compared to the previous edition are as follows.

— The size of the test specimens has been defined as (50 mm ± 1 mm) × (50 mm ± 1 mm). A fixed size

allows the determination of any edge effects associated with the area 5 mm from the outer edge (see

new Annex C). In this way, the evaluation of growth on the test specimens is harmonized.

— New Annexes B and C have been added and the old annexes have been renumbered.
— The former Annex C has been updated and renumbered as Annex D.
— Test A only:

Stainless steel coupons acting as negative control specimens have been introduced to provide a

reference for where fungal growth occurs in the Petri dish, even though no nutrients have been

added to the test design.

The test design does not use an agar-medium any more to provide the source of moisture to allow

95 % ± 5 % relative humidity to be achieved. Instead the test specimens are stored in closed

containers that include a water reservoir to provide a relative humidity 95 % ± 5 % around the test

specimens during incubation;

A grid has been introduced for use during the evaluation of the area of growth observed on the

surface of the test specimens. The use of the grid provides and objective mechanisms for assessing

growth and is explained in the new Annex C.
— Test B has been deleted.

— Positive control specimens (test specimens that allow fungal growth) have been introduced to allow

the determination of basic fungistatic effects of samples that contain biocides.
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SIST EN ISO 846:2019
ISO 846:2019(E)

— The fungal inoculum has been revised to be consistent with other referenced test standards and

changes to the names of fungal strains have been incorporated.

— The media used in the test have been revised based on the experience of various laboratories.

— A staining method has been proposed to aim assessment.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
vi © ISO 2019 – All rights reserved
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SIST EN ISO 846:2019
ISO 846:2019(E)
Introduction

Under certain climatic and environmental conditions, microorganisms can settle on and colonize the

surface of plastics or plastics products. Their presence and/or their metabolic products might not

only damage the plastic itself, but can also affect the serviceability of building materials and systems

containing plastic parts.

The tests and test conditions specified in this document are empirical and cover most but not all

potential applications.

For specific applications and for long-term tests, procedures which reflect performance under actual

conditions are agreed upon.

The actions of microorganisms on plastics are influenced by two different processes.

a) Direct action: the deterioration of plastics which serve as a nutritive substance for the growth of

the microorganisms.

b) Indirect action: the influence of metabolic products of the microorganisms, e.g. discolouration or

further deterioration.
This document deals with both processes as well as their combined action.

Changes to the method are based on discussions among laboratories that have performed the test for

at least 5 years. On an international level, discussions have taken place within the Plastic Group of the

International Biodeterioration Research Group (IBRG) between scientists with extensive experience

with this document as well as the testing of the interaction between microorganisms and plastics.

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SIST EN ISO 846:2019
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SIST EN ISO 846:2019
INTERNATIONAL STANDARD ISO 846:2019(E)
Plastics — Evaluation of the action of microorganisms

WARNING — Handling and manipulation of microorganisms which are potentially hazardous

requires a high degree of technical competence. Only personnel trained in microbiological

techniques should carry out such tests. Codes of practice for disinfection, sterilization and

personal hygiene shall be strictly observed. It is recommended that workers consult IEC 60068-

2-10 and ISO 7218.
1 Scope

This document specifies methods for determining the deterioration of plastics due to the action of fungi

and bacteria and soil microorganisms. The aim is not to determine the biodegradability of plastics or

the deterioration of natural fibre composites.
The type and extent of deterioration can be determined by
a) visual examination and/or
b) changes in mass and/or
c) changes in other physical properties.

The tests are applicable to all plastics that have an even surface and that can thus be easily cleaned. The

exceptions are porous materials, such as plastic foams.

This document uses the same test fungi as IEC 60068-2-10. The IEC method, which uses so-called

“assembled specimens”, calls for inoculation of the specimens with a spore suspension, incubation of

the inoculated specimens and assessment of the fungal growth as well as any physical attack on the

specimens.

The volume of testing and the test strains used depend on the application envisaged for the plastic.

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 13934-1:2013, Textiles — Tensile properties of fabrics — Part 1: Determination of maximum force and

elongation at maximum force using the strip method
EN 10088-1, Stainless steels — Part 1: List of stainless steels

EN 10088-2, Stainless steels — Part 2: Technical delivery conditions for sheet/plate and strip corrosion

resisting steels for general purposes

EN 13697:2015, Chemical disinfectants and antiseptics — Quantitative non-porous surface test for the

evaluation of bactericidal and/or fungicidal activity of chemical disinfectants used in food, industrial, domestic

and institutional areas — Test method and requirements without mechanical action (phase 2, step 2)

IEC 60068-2-10, Environmental testing — Part 2-10: Tests — Test J and guidance: Mould growth

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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SIST EN ISO 846:2019
ISO 846:2019(E)

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
biodeterioration

undesired change in the properties, such as colour, strength, mass, of a material due to the action of a

microorganism
3.2
fungistatic effect

antimycotic effect of an antimicrobial treatment which prevents a given material from being overgrown

by fungi under moist conditions
4 Principle
4.1 General

The test involves exposing test specimens of plastic to the action of selected test strains of fungi and

bacteria (or, in the case of the soil-burial test, to microbially active soil) for specified or agreed periods

of time under specified conditions of temperature and humidity.

At the end of the exposure, the test specimens are assessed before and/or after cleaning by visual

examination and/or any change in mass or other physical properties is determined.

The results obtained with the specimens exposed to microorganisms (test series I) are compared with

those obtained from retained reference specimens (test series 0) or sterile specimens (test series S)

kept under the same conditions.

In the case of testing fungistatic properties, a visual assessment is made between test specimens free of

biocides and with those containing biocides to demonstrate the effect of a biocide in a qualitative manner.

Short descriptions of the test methods used to determine the resistance of plastics to fungi (method A)

or the fungistatic effects (method B), resistance to bacteria (method C) and resistance to soil

microorganisms (method D) are given in 4.2 to 4.4.
4.2 Resistance to fungi
4.2.1 Method A: Fungal-growth test

Test specimens are exposed to a mixed suspension of fungal spores in the presence of a humidity ≥95 %

relative humidity. After the limited nutrients from the spore itself are depleted through formation of

a germination tube, the fungi can only grow at the expense of the material of the test specimens. If

the specimens contain no nutritive component, the fungi cannot develop mycelia and there will be no

deterioration of the plastic.

Method A is suitable for the assessment of the inherent resistance of plastics to fungal attack in the

absence of other organic matter.
4.2.2 Method B: Determination of fungistatic effects

Test specimens are exposed to a mixed suspension of fungus spores in the presence of a complete

nutrient medium, i.e. with a carbon source. Even if the plastic does not contain any nutritive elements,

the fungi can grow over the specimens and their metabolic products can attack the material by

metabolizing the nutrient-agar medium.
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ISO 846:2019(E)

Any inhibition of growth either on the plastic or in the nutrient-agar medium (zone of inhibition) shows

fungistatic activity of the plastic or the presence of a fungicidal treatment.

In order to show a basic qualitative effect of a biocide in a plastic material, specimens free from biocide

shall be included in the test. Only if these biocide-free specimens show more growth than the specimens

containing biocides can a qualitative indication of fungistatic or fungicidal efficacy be determined.

4.3 Method C: Resistance to bacteria

The action of bacteria on test specimens is assessed using an incomplete medium without a carbon

source . If there is no growth in the agar surrounding the specimen, then the specimen does not contain

any nutritive components.

If a material to be tested claims added functionality, such as a product with hygienic effects, the plastic

material should be tested according to ISO 22196 which provides guidance for measuring the basic

antibacterial performance of non-porous (plastic) materials that have been treated with a biocide with

the intention of introducing antibacterial/hygienic properties into that material.

4.4 Method D: Resistance to microbially active soil (soil-burial test)

Test specimens are completely buried in natural soil with a known water-holding capacity and a

specified moisture content (see Annex A).

The soil-burial test has been included in this document because many plastics are used in permanent

contact with soil and exposed to high humidities.
4.5 Choice of properties for assessment of biodeterioration

The choice of the properties to be determined depends on the aim of the test. A visual assessment of

biological attack shall always be made as the first stage in assessing the resistance of the plastic.

It is recommended that determinations be made of those properties which clearly indicate surfac

...