EN ISO 846:1997

SLOVENSKI STANDARD
01-maj-1999
Polimerni materiali - Vrednotenje delovanja mikroorganizmov (ISO 846:1997)
Plastics - Evaluation of the action of microorganisms (ISO 846:1997)
Kunststoffe - Bestimmung der Einwirkung von Mikroorganismen auf Kunststoffe (ISO
846:1997)
Plastiques - Evaluation de l'action des micro-organismes (ISO 846:1997)
Ta slovenski standard je istoveten z: EN ISO 846:1997
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

IS0
INTERNATIONAL
STANDARD
Second edition
1997006- 15
Evaluation of the action
Plastics -
of microorganisms
Plastiques - haha tion de /‘action des micro-organismes
Reference number
IS0 846:1997(E)
IS0 846: 1997(E)
Page
Contents
iv
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.
Introduction
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 Scope
................................................................
2 Normative references
..................................................................................
3 Definitions
Principle .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 Apparatus and materials
Test specimens .
..........................................................
7 Preparation of specimens
Procedures .
...............................................................................
9 Assessment
Expression of results .
.................................................
11 Accuracy of the measurements
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12 Test report
..~............................................................................
13 Bibliography
Annexes
A Determination of the water content and water-holding capacity
of a soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B Precision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C Information on test fungi
0 IS0 1997
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
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Printed in Switzerland
ii
Q IS0 IS0 846: 1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 846 was prepared by Technical Committee
lSO/TC 61, Plastics, Subcommittee SC 6, Ageing, chemical and environ-
mental resistance.
This second edition cancels and replaces the first edition (IS0 846:1978),
which has been technically revised.
The Plastics Project Group of the IBRG (International Biodeterioration
Research Group) carried out several interlaboratory tests between 1984
and 1990, using the 1978 edition of this standard, with the aim of checking
the reproducibility of the test results. The experience gained from these
tests has been incorporated in the present edition. In addition, a soil-burial
test method has been included in subclause 8.5, based on a specification
the Eidgenossische Materialprijfungsanstalt in St. Gallen, Switzerland.
Annex A forms an integral part of this International Standard. Annexes B
and C are for information only.
. . .
III
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IS0 846: 1997(E)
Introduction
Under certain climatic and environmental conditions, microorganisms may
settle on and colonize the surface of plastics or plastics products. Their
presence and/or their metabolic products may not only damage the plastic
itself, but may also affect the serviceability of building materials and
systems containing plastic parts.
The tests and test condit :ions l specif #ied in this lnternationa ,I Standard are
empirical and cover most- but not all- poten tial applications.
For specific applications and for long -term tests, procedures
agreed upon which reflect performance under actual conditions.
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;
indirect action: the influence of metabolic products of the micro-
b)
or fu rther deterioration.
organisms, e.g. discolouration
This International Standard deals with both of these two processes, as well
as their combined action.
iv
-
IS0 846:1997( E)
INTERNATIONAL STANDARD 0 Iso
Plastics - Evaluation of the action of microorganisms
WARNING - Handling and manipulation of microorganisms which are potentially hazardous requires
a high degree of technical competence and may be subject to current national legislation and regulations.
Only personnel trained in microbiological techniques should carry out such tests. Codes of practice for
disinfection, sterilization and personal hygiene must be strictly observed.
It is recommended that workers consult IEC 6812110:1988, appendix A “Danger to personnel”, and
General rules for microbiological
IS0 7218:1996, Microbiology of food and animal feeding stuffs -
examinations.
1 Scope
This International Standard 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.
The type and extent of deterioration may be determined by
a) visual examination
and/or
b) changes in mass
and/or
changes in other physical properties.
C)
The tests are applicable to all articles made of plastic that have an even surface and that can thus be easily
cleaned. The exceptions are porous materials, such as plastic foams.
This International Standard uses the same test fungi as IEC 68-2- 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 will depend on the application envisaged for the plastic. These
parameters should therefore be agreed upon before the tests and should be stated in the test report.

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2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 291 :-I), Plasfics - Standard atmospheres for conditioning and testing.
IEC 68 -2 - IO: 1988, Basic environmental testing procedures - Par? 2: Tests - Test J and guidance: Mould growth.
3 Definitions
For the purposes of this International Standard, the following definitions apply:
3.1 biodeterioration: A change in the chemical or physical properties of a material due to the action of a
microorganism.
3.2 fungistatic effect: The antimycotic effect of an antimicrobial treatment which prevents a given material from
being overgrown by fungi under moist conditions.
3.3 biodegradation: The term “biodegradation” is being discussed by TC 61/SC 5/W/G 22, Biodegradability, and
the official definition will be included here when it is available.
4 Principle
4.1 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 clean ing by visual examination
r other physical properties is determined.
and/or change in mass o
any
(batch I) are compared with
The results obtained with the specimens exposed to biological attack those obtained
from untreated specimens (batch 0) or sterile specimens (batch S) kept under the sa ,me conditions.
4.2 Short descriptions of the test methods used to determine the resistance of plastics to fungi (method A)
or the fungistatic effects (methods B and B’), resistance to bacteria (method C) and resistance to soil
microorganisms (method D) are given below.
4.2.1 Resistance to fungi
4.2.1.1 Method A: Fungal-growth test
Test specimens are exposed to a mixed suspension of fungus spores in the presence of an incomplete nutritive
medium (without a carbon source). The fungi can only grow at the expense of the material. If the specimens contain
no nutritive component, the fungi cannot develop mycelia and there is no deterioration of the plastic.
1) To be published. (Revision of IS0 291:1977)
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Method A is suitable for the assessment of the inherent resistance of plastics to fungal attack in the absence of
other organic matter.
It is recommended that, when method A is carried out, methods B and B’ are also carried out to assist in the
interpretation of the results.
4.2.1.2 Methods B and B’: Determination of fungistatic effects
Test specimens are exposed to a mixed suspension of fungus spores in the presence of a complete 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.
Any inhibition of the growth either on the plastic or in the growth medium (zone of inhibition) shows fungistatic
activity of the plastic or the presence of a fungicidal treatment.
In method B’, the specimens are not placed on the nutritive medium until it is completely overgrown.
Methods B and B’ are used when surface contamination is expected. In order to save time, and for a better
understanding of the phenomenon, it is recommended that the two methods are carried out simultaneously.
4.2.2 Method C: Resistance to bacteria
The action of bacteria on test specimens is assessed using a n incomplete medium. If there is no g rowth in the agar
round the specimen, then the specimen does not contain any nutritive components.
4.2.3 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 International Standard because many plastics are used in permanent
contact with soil and exposed to high humidities.
4.3 Choice of properties for assessment of biodeterioration
The choice of the properties to be determined depends on the aim of the test. A visual assessme nt of biological
attack should preferably always be made as the first stage in assessing the resistance of the plastic.
The measurement of changes in mass is recommended, especially for those plastics that contain biologically
degradable substances, such as plasticizers, lubricants and stabilizers (as in plasticized PVC, for instance). The
measured loss is, in this case, often lower than the actual loss as the biologically degradable substance is only
partly utilized and the metabolic products often remain in the plastic.
When, above a .II, the surface is affected, it is recommended that determinations be made of those properties which
clearly indicate surface changes, such as surface gloss, flexural properties, impa ct resistance and hardness.
5 Apparatus and materials
5.1 For all tests
5.1 .l Incubators
That used for tests involving fungal and bacterial attack shall be capable of controlling the temperature to -t-j OC
at any temperature from 20 “C to 35 “C at a relative humidity of 90 % or greater.

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That used for soil-buri
...