Technical Notes for Guidance
Guidance document on the evaluation of efficacy of
disinfectants PT2
These Technical Notes for Guidance
were endorsed during the 51st CA meeting for release for a 6-month
consultation period of stakeholders.
At the end of this consultation
period, these Technical Notes for Guidance would, if appropriate, be revised on
the basis of the comments received.
Meanwhile, Member States competent
authorities and stakeholders could already apply the principles laid down in
these Technical Notes for Guidance.
PRODUCT TYPES 1 TO 5 -
DISINFECTANTS AND GENERAL BIOCIDAL PRODUCTS
Only Product type 2, is described in more
detail. Other product types will follow later.
DRAFT Guidance (version 19) to replace part of
Appendices to chapter 7 (page 111 to 134) from TNsG on Product evaluation
This chapter deals with the
evaluation methodology of efficacy tests for disinfectants for the national
authorisation of products under the EU Biocidal Products Directive 98/8/EC (BPD)
and the EU Biocidal Products Regulation 528/2012 (BPR).
The general introduction is written
for disinfectants in Main Group 1 (PT 1 to 5). Detailed guidance is currently
only available for PT2, and guidance on the other PTs will be included at a
later date. This guidance is a “living document”, which will be revised
regularly.
This chapter describes the nature and extent of
data which should be available to support the label claims for biocidal
products within the Main Group 1: Disinfectants. This group covers 5 product
types:
Product type 1: Human
hygiene
Products in this group are biocidal products
used for human hygiene purposes, applied on or in contact with human skin or
scalps for the primary purpose of disinfecting the skin or scalp.
Product
type 2: Disinfectants and algaecides not
intended for direct application to humans or animals
Products used for the disinfection of surfaces,
materials, equipment and furniture which are not used for direct contact with
food or feeding stuffs.
Usage areas include, inter alia, swimming
pools, aquariums, bathing and other waters; air-conditioning systems; and walls
and floors in private, public, and industrial areas and in other areas for
professional activities.
Products used for disinfection of air, water not used for human or animal
consumption, chemical toilets, waste water, hospital waste and soil.
Products used as algaecides for treatment of swimming
pools, aquariums and other waters and for remedial treatment of construction
materials.
Products used to be incorporated in textiles,
tissues, masks, paints and other articles or materials with the purpose of
producing treated articles with disinfecting properties.
Product type 3: Veterinary
hygiene
Products used for veterinary hygiene purposes
such as disinfectants, disinfecting soaps, oral or corporal hygiene products or
with anti-microbial function. Products used to disinfect the materials and surfaces
associated with the housing or transportation of animals.
Product type 4: Food
and feed area
Products used for the disinfection of
equipment, containers, consumption utensils, surfaces or pipework associated
with the production, transport, storage or consumption of food or feed
(including drinking water) for humans and animals.
Product type 5: Drinking
water
Products used
for the disinfection of drinking water for both humans and animals.
Products in this main group are meant for the control
of micro-organisms, such as bacteria (including vegetative cells, spores and
mycobacteria), fungi (including moulds and yeasts), and viruses (including
bacteriophages), algae and protozoa. Control may be carried out on inanimate
surfaces or skin or in liquids.
The most important fields of use include the
medical, veterinary, and food and drinking water sectors. Applications in
public, commercial and industrial areas, where application is to surfaces
without direct contact with food are included in Product type 2. If contact
between disinfected surfaces and food is possible (e.g. food industry, private
and restaurant kitchens), applications are included in Product type 4.
Disinfectants for
medical instruments and medical equipment that are considered medical
devices are covered under
the Medical Device Directive 93/42/EEC. However, disinfectants with a broader claim, e.g. disinfection of
instruments and surfaces, are under the BPD or BPR.
Cleaning products which are not intended as
biocides, including liquid detergents, washing powders etc., are excluded
from these product types.
Treated articles with claimed disinfecting or
biostatic properties or function also fall within PTs 1 to 5, when they have a
primary biocidal function. These articles can include a wide variety of
products, with different applications, matrices etc..
There is currently little guidance on data
requirements and acceptance criteria available for treated articles. A chapter
on treated articles will be included in this guidance at a later date.
A “Glossary of Terms” is included as Appendix 1
of this chapter.
The following aspects are relevant for the
evaluation of the efficacy of disinfectants:
1.
The
label claim and instructions for use
2.
Efficacy
data of the product
3.
The
possible occurrence of resistance, cross resistance or tolerance.
1.3 Label claim
For each product, clear label claims should be provided. When the label
itself cannot contain all the necessary information, any accompanying
leaflet containing instructions
for use should also be considered. To simplify the text only the term
"label claim" will be used below.
The types of efficacy claims made for a disinfectant depend upon, among other
things, the types of micro-organisms the disinfectant targets (e.g. fungi,
yeasts, (myco)bacteria or bacterial spores) and the disinfectant’s intended use
(e.g. in hospitals, in contact with food, in stables). Label claims and
recommendations for use, including concentration and contact time, must be
supported by the results of bactericidal, fungicidal, etc. tests appropriate to
the area of application, which are normally performed on the basis of the
specific standards.
Applicants must clearly indicate the spectrum of antimicrobial activity
claimed for the proposed product on the product label.
Examples of the common fields of applications
are presented in Appendix 2: Claim matrix (note: this list is not intended to
be exhaustive).
1.3.1 Target
organisms
The target organisms for which claims are made should be specified on
the product label.
As the claimed antimicrobial efficacy for disinfectant products will
encompass a large spectrum of potential target organisms, it is not necessary
or indeed feasible to include all the possible micro-organisms in an efficacy
test designed to support a label claim.
Instead the types of target organism the product is intended for are mentioned,
e.g. fungi, yeasts, viruses, algae, protozoa, (myco)bacteria or spore forming
bacteria. Specifying the groups of
organisms (e.g. bacteria, fungi) is also relevant as products are not normally
specific to single species.
Specific species are mentioned on the label where they are the only or
most relevant organism, or where they have a different susceptibility to
biocides than the rest of the group. For instance, mycobacteria are less
susceptible then other bacteria and it is only relevant to control them in
certain situations such as tuberculosis wards.
In general it is not possible to claim against specific single species
without claiming (and demonstrating) efficacy against the group of organisms
(e.g. no claim against Mycobacterium tuberculosis without also making a
general bactericidal claim, no claims against Rotavirus without a general
virucidal claim). However, there are some cases in which it can be justified
that a single or a small number of species are relevant (for instance
bacteriophages in milk industry).
Standard test methods normally specify one or more representative
species that should be tested per group of organisms claimed. For instance, a
bactericidal product should be tested on gram-positive and gram-negative
bacteria, a fungicidal product should be tested on yeast and fungi. The species
used are representative species that take into account their relevance to
practical use, susceptibility for disinfectants and adequacy for laboratory
testing.
The test organisms and strains which should be used are normally stated
in standard efficacy test methods, i.e. according to EN 14885 or OECD-guidance
and guidelines.
When it is not possible to use standard test methods for efficacy
testing and other tests are used, the test organisms listed in Appendix 4
should be employed. If test organisms other than those listed in Appendix 4 are
used, their relevance should be justified.
Wherever possible strains should be selected from international
collections (their genetic stability should be checked regularly). The
preservation procedures must be clearly described (EN12353).
Other test organisms, in addition to those specified in the test
standards, can also be tested. When efficacy against specific additional
species is claimed, efficacy tests with those species should also be performed.
In general, claims should not be made against the specific reference species
used in a standard test as this can give a misleading impression that the
product shows activity beyond that covered by the general (e.g. bactericidal,
fungicidal) claim.
Mentioning specific organisms on the label is still subject of
discussion between Member States. The above paragraphs reflect the position at
the time this guidance is written.
Disinfectants are used almost everywhere people
want to “eliminate” micro-organisms. They are used to kill or irreversibly
inactivate bacteria, fungi and viruses on animate and in-animate surfaces and
matrices, in hospitals, households, schools, restaurants, offices, swimming
pools, kitchens, bathrooms, dairy farms, on medical and dental instruments,
eating utensils and at many other locations.
Applicants should clearly indicate the intended areas of use for the
product on the label e.g. areas of use could include (not exhaustive):
Hospital and other medical areas
Domestic use
Institutional use (offices, schools etc.)
Industrial applications, e.g. food, cosmetic, pharmaceutical industry
etc.
Veterinary areas (animal housing, animal health care etc.)
Recreational areas
In addition to the types of efficacy claimed (e.g. bactericidal,
fungicidal, tuberculocidal) and the intended area of use, the applicant must
specify the use patterns for which the disinfectant is recommended on the
label.
Broad examples of use patterns (not exhaustive) could include areas such
as:
· Use on intact skin
· Use in hospitals, operating
theatres, isolation wards, use on instruments etc.
· Use in food manufacturing,
retailing, processing areas etc.
· Use in animal housing and equipment,
e.g. pigs, sheep, poultry etc.
· Use on work surfaces, cutting boards
etc.
· Use on fabrics or textiles
· Use on toilets, bathrooms, sinks,
etc.
· Use against micro-organisms
associated with human or animal wastes
· Use in air conditioning systems
· Use in swimming pools, spas,
aquariums and bathing waters
· Use in tanks, pipelines, equipment
soak or bottle wash
The label claim must specify the application method of the product. For
disinfectants there is a broad range of application methods (e.g. aerosol,
wiping, spraying). The in-use concentration of the solution and the contact
time, which are essential for safe and effective use, should be described on
the label. Any other directions for use should also be specified, such as
whether the surface should be cleaned first, and claims regarding the number of
times a prepared use solution of an antimicrobial product can be used (or
re-used) before a fresh solution must be prepared.
The application method can have a strong influence on the efficacy of a product,
therefore the testing of a product should be appropriate for the application
method. If specific equipment is used for application of the product (e.g.
vaporisers) this should be taken into account when testing the product for
efficacy.
Any other circumstances that can effect the
efficacy of a product should be mentioned on the label (e.g. temperature or pH
requirements). For example, when a surface should be cleaned before applying
the biocide and no rinsing step is involved, alkaline cleaning fluids should
not be used with acidic biocides, and vice versa.
For efficacy testing of disinfectants in
general only quantitative tests methods should be used.
For efficacy testing of disinfectants a tiered
approach is recommended. The following tiers can be distinguished (in
accordance with EN 14885: 2006):
Phase 1 tests are quantitative
suspension tests to establish that a product has bactericidal, fungicidal,
virucidal etc. activity without regard to specific conditions of intended use.
Phase 2 comprises two steps:
Phase 2 step 1 tests are
quantitative suspension tests to establish that a product has bactericidal,
fungicidal, virucidal etc. activity, simulating practical conditions
appropriate to its intended use.
Phase 2 step 2 tests are
quantitative laboratory tests, often using carriers or living tissues with
dried-on micro-organisms, simulating practical conditions to establish that the
product has bactericidal, fungicidal, virucidal etc. activity.
Phase 3 tests are field tests under practical
conditions.
1.4.1.1 Phase 1
Phase 1 tests are laboratory suspension tests
to establish the basic activity of the product or active substance. These tests
may be used during the development of the product, but are not accepted for
product authorisation. However, a phase 1 test can be used to demonstrate that
a co-formulant does not have any biocidal activity in the product.
1.4.1.2 Phase 2 step 1
Phase 2 step 1 tests are laboratory suspension tests in which the
ultimate purpose is to establish at what concentrations the product meets
specified requirements under “in-use” conditions. In these tests in-use
conditions (e.g. temperature, contact time, interfering substances) are
considered in the test method.
Various laboratory methods have been developed for biocide activity
testing.
Although these experiments differ in their design and experimental detail, they
are all based on the principle of adding a test inoculum to disinfectant (or
vice versa) and taking samples at specified times. The biocide in each sample
is then neutralised and the survival of the organisms assessed. In practice the
methods can be classified into 2 groups, according to how the end-point of the
test is determined:
Quantitative tests
Samples of untreated and biocide-treated cells are plated on nutrient
medium after neutralisation. After incubation, the number of colony forming
units is determined and the log reduction in viable counts determined.
Capacity tests
The biocide is challenged successively with the test organism at defined
time intervals. This type of test can be used for instance for swimming pools
and toilet disinfectants which are challenged by new bacteria periodically.
Following each inoculation samples are taken, and after a suitable contact
period has elapsed, the biocide is neutralised and the sample incubated in a
suitable growth medium to determine the surviving micro-organisms. The result
is expressed as the amount of the accumulated inoculum that was required to
produce the “failure”.
1.4.1.3 Phase 2 step 2
Phase 2 step 2 tests are simulated use or
practical tests, which mimic real-life conditions, for instance by pre-drying
the micro-organisms onto surfaces. These tests are used in a second testing
stage. After measuring the time-concentration relationship of the disinfectant
in an in-vitro test (phase 2 step 1), these practical tests are performed to
verify that the proposed use dilution is likely to be adequate in real life
conditions. For several uses standardised simulated use tests exist (surface
disinfection, hand wash or rub, instrument disinfection) but there are no
standard tests available for many others.
Longer-lasting activity is claimed for some products. When these
products are applied to surfaces, it is common that they will not be completely
removed or rinsed off after application. This might lead to longer-lasting
activity of the biocide on the surface, which can be determined by modified
efficacy tests.
1.4.1.4 Phase 3 Field or in-use tests
In-use testing involves the antimicrobial evaluation of the product
under actual conditions of use on specified surfaces or materials in a
specified environment. As with standard and non-standard laboratory methods, representative
organisms or actual organisms of concern may be used.
Validated methodologies for these types of tests are not currently
available, although some are in development.
The practical use conditions under which a product can be used can be
very variable and are therefore difficult to standardise. Field tests, although
not standardised, can however give valuable additional information on the
efficacy of the product, provided that the studies are scientifically robust,
well reported and provide a clear answer to the question. In these types of
test, a control treatment without biocide should be included. Where this is not
possible, efficacy should be judged on a comparison of the situation before and
after application.
Until validated standards are prepared, the responsibility for
determining the acceptability of data derived from field trials in support of
the claim will lie with the Competent Authority.
Ideally, data should be generated using
international or national recognised testing methods (CEN, OECD, ISO, etc.).
Several international standard test methods currently exist for disinfectant
products. A list of recommended standard tests is presented in Appendix 3 to
this document.
If there are no guidelines available for the
specific use of a product or guidelines are not suitable, the applicant may use
other methods (such as intra-company Standard Operating Procedures), where the
studies are scientifically robust, well reported and provide a clear answer to
the question. In addition, the test methods used, together with the test
conditions, should be clearly and fully described and must address the efficacy
claim that appears on the product label. The use of existing guidelines, with
revisions to make the guideline more suitable for the specific product or use
conditions, is also possible.
At the time of production of this guidance document, a broad range of
CEN methods is available, as described in Appendix 3. Further the development
of a series of phase 2 / step 2 methods for the disinfection on hard surfaces
is under progress by the CEN and OECD. The use of CEN or OECD test methods is
highly recommended, where these are available and relevant.
These methods described below typically give a standard set of test
parameters, test organisms and pass criteria. Where specific conditions apply
for a field of use, such as high/low level soiling, high/low temperatures,
relevant contact times etc., these conditions should be included in the
efficacy tests.
1.4.2.1 CEN Standard Test Methods
A Technical
Committee (TC 216) was established in the European Committee for
Standardisation (CEN), to produce harmonised European methods for testing the
activity of disinfectants used in medical, veterinary, food, industrial,
domestic and institutional areas. The standards are based on suspension tests
(phase 1 and phase 2/step 1) and some simulated use tests like surface tests
(phase 2/step 2).
European standard EN 14885 gives information on the application and
interpretation of European Standards for the testing of chemical disinfectants
within product types 1, 2, 3 and 4 of the Directive / Regulation.
This document outlines the various standards currently available and provides
guidance as to the choice of available standards that may be
used to demonstrate the effectiveness of disinfectants in particular situations
(such as medical, veterinary and food hygiene) and on the interpretation of
results from such tests in making and supporting efficacy claims.
In EN14885 products intended for domestic use are grouped with products
for use in food and industrial areas, and therefore the tests specified are not
always relevant to domestic areas. For instance, the virus test EN13610 only
tests on phages. In these cases the test from the medical area should be used
where relevant. In cases where no test method is available for one area of use
(e.g. sporicidal test in medical area), a test from another area can be used
instead, provided that the test parameters (soiling, temperature, etc.) are
adapted to the intended use area.
The application of disinfectants to water systems such as swimming
pools, spas, and drinking water is not addressed in EN 14885 (2006). For the
evaluation of activity against Legionella in aqueous systems (water
used in cooling towers and water for general purposes, like spas, pools,
showers and other uses) a
quantitative suspension test is available (EN 13623).
CEN TC 216 is revising EN 14885 and the new version will include
guidance on how a field trial shall be conducted. This guidance is intended to
advise on the factors to be taken into account and controlled when carrying out
a field trial.
The use of CEN test methods is highly recommended, provided that the
methods are applicable for the use of a product. In some cases, the method can
be adapted (other contact time, soiling, etc.) to fit the use conditions. Any
deviation from a standard must be clearly described and a justification for any
deviations provided.
1.4.2.2 OECD Standard Test Methods
OECD has several draft phase 2/step 2 test methods for the efficacy
testing of disinfectants to be used on hard surfaces under development,
although it is currently uncertain if they will be accepted as Test Guidelines
or as Guidance Documents. Guidelines on the testing of disinfectants used in
treated articles are also in preparation.
An OECD guidance document “Guidance document on the evaluation of the
efficacy of antimicrobial treated articles with claims for external effects”
and an OECD Guidance Document for pool and spa disinfectants have been
published.
As with the CEN test methods, the use of OECD test methods is also
highly recommended, provided that the methods are relevant to the use of a
product. Again, the methods can be adapted (other contact time, soiling, etc.)
to better fit the use conditions, provided that any deviations from the
standard are clearly described and justified.
1.4.2.3 Other Standard Test Methods
While CEN and OECD standards are highly recommended,
there are circumstances in which these tests cannot be applied, i.e. they are
not available, or relevant to a particular product or use pattern. In those
cases other test methods can be used.
Other test methods, e.g. DGHM, EPA, AOAC or
ASTM methods, are available and might be used when no international standard is
available for a specific application. Where these methods lack predefined test
parameters, target organisms or pass criteria, the applicant has to provide
evidence why the chosen parameters are appropriate for the intended
application.
Where no standard tests are available, suitable
test protocols may be designed (and justified) by the applicant, but these
should be discussed with and agreed by the Competent Authority before testing takes
place.
Label claims and recommendations must be
supported by the results of tests appropriate to the area of application.
In each test the composition of the tested
product should be clearly described: including the identity of the active
substances and co-formulants, and their concentrations in the tested
formulation. As the formulation may affect the efficacy of the product, the
composition of the product tested should be the same as the product under
consideration. If not, justifications should be provided for any differences,
and these will be assessed on a case by case basis. In cases where the test
report does not report the formulation of the test product (e.g. it may only
state a code for the product for the purposes of confidentiality with the
testing organisation), the full composition of the product should also be
provided.
As Phase 1 tests do not take practical use
conditions into account, they are not considered acceptable to support
claims during product authorisation. In general phase 1 tests are used during
the development of the product, for inclusion of an active substances on Annex
I of the BPD or “Union list of approved substances” under the BPR or to prove
that a co-formulant has no biocidal activity.
In general at least phase 2 step 1 and step 2
tests are required to support label claims during product authorisation. The
phase 2 step 1 test will provide basic information on the efficacy of the
product (in a standard test) that can be compared to similar biocides, while
phase 2 step 2 tests investigate the effects of more in-use factors (such as
interfering substances). The combination of phase 2 step 1 and step 2 tests
will generally provide a robust data package to demonstrate the efficacy of a
product. Deviations from the tiered approach should be justified.
In some cases, e.g. when disinfection is done
in suspension under real use conditions, a phase 2 step 1 test is sufficient on
its own, as this already simulates practical conditions.
A phase 2 step 2 test may be replaced by a
phase 3 test where a phase 2 step 2 tests is not appropriate. In general, a
phase 3 test will be done in combination with a standard phase 2 step 1 test,
as phase 3 tests are often variable.
Where in-use conditions cannot be simulated,
phase 3 tests are required (e.g. drinking water disinfection with ionisation
equipment).
If more than one test method is available and
applicable in phase 2, step 2 to substantiate a label claim for efficacy, it is
sufficient to provide data from only one of the test methods. The test method
selected should be one which best represents the way in which the product is
used. For example, in the case of a disinfectant used for “hard, non-porous
surfaces by spraying”, the test method should be one for such surfaces without
mechanical action and with representative conditions of use, such as contact
time, soiling, temperature and test organisms.
Tests have to be performed with relevant target
organisms, which are selected in accordance with the standard and the intended
use of the product. This is further discussed in Section 1.3.1. A list of
standard test organisms in given in Appendix 4.
The concentrations used in testing should be
selected to demonstrate the threshold of product efficacy. Suspension test should
be performed with several dose rates, including at least one rate lower than
the effective rate. Competent Authorities will evaluate dose response data
generated in these tests in order to assess if the recommended dose is
appropriate (i.e. the concentration is not too high, or at the minimum) to
achieve the desired effect.
For biocidal products which claim a biostatic
effect (bacteriostatic, fungistatic, etc. i.e. the ability to inhibit growth of
bacteria, fungi etc. without killing them) both suspension and surface tests
should be performed. The suspension test should be performed with and without
neutralisation and with a water control (where water is tested instead of the
product). The results from this testing should show that the product prevents
growth of the test micro-organism (i.e. a lower level of test organism compared
to the water control) but does not necessarily inactivate them (the
micro-organism survive in the test without neutralisation).
Biocidal products that claim a biostatic effect
bear the risk of development of resistant organisms. For this reason, efficacy
of these types of products has to be examined carefully.
Other products, which do not have biocidal or
biostatic activity, might fall within the scope of BPD or BPR, i.e. which
“deter, render harmless, prevent the action or otherwise exert a controlling
effect on any harmful micro-organism”. No EU standards are available for these
types of product yet, so applicants should provide a method following the
principles of this guidance and based on scientific evidence. During
development of new tests, or when an applicant is considering using a
non-standard test or using novel testing methods, they should discuss this with
the Competent Authority as to the acceptability and applicability of the test.
In the following sections, guidance on the
requirements per product type and use will be given.
A detailed but non-exhaustive list of most
relevant product applications and uses of biocides, together with the required
test methodology, is given in Appendix 2 (Claims matrix).
1.4.4 Relevant
factors of the test procedure
1.4.4.1 Formulation
of the tested product
A product authorisation is given to a specific
product with a defined composition, and the efficacy of this specific
formulation should be demonstrated. Therefore it is important that the
formulation tested is clearly reported in each test report (or provided
alongside the test report with a statement that it is the formulation which has
been tested). The formulation details should specify the active substances and
co-formulants present, together with their respective concentrations, and
should confirm that all tested formulations contain the same co-formulants and
concentrations. Any deviations should be mentioned and justified in a statement
or in the relevant efficacy reports. Where there are deviations in the
formulation from that in the product for which authorisation is sought, the
tests will only be considered relevant where it is evident that the deviations
have no effect on efficacy.
1.4.4.2 Hard
Water Claims
The degree of hardness of the water used to dilute the disinfectant may
affect its performance (by the presence of metal ions such as Ca2+ and Mg2+).
Generally the harder the water is, the less effective the diluted disinfectant
will be. Therefore, test programmes which require that products are diluted
with potable water must be diluted in water of standard hardness for the
purpose of efficacy testing.
It follows that any product that carries label claims for effectiveness
in hard water must be tested by the appropriate method in water with defined
hardness at the level claimed.
1.4.4.3 Presence
of Interfering Substances
Where disinfectants are applied to either inanimate surfaces or the
hands, substances may be present on the surface which may affect the
disinfectant’s activity.
The nature, amount and condition of the soiling present will affect the
efficacy of a disinfectant.
In many cases, however, residual contamination must be expected, and in
some situations (e.g. in the treatment of blood spillages) disinfectants are
specifically used to decontaminate soiling, to prevent infection transfer and
to assist in safe disposal.
Blood, urine, faeces, food debris, fats and oils, dust and proteinaceous
materials are the most likely organic soils to be encountered. Limescale,
milkstone and soil are the most common inorganic soils.
Where claims are made for use under soiled or dirty conditions, the use
concentrations of the product must be determined from tests carried out in the
presence of suitable soil. Soiling materials commonly used in efficacy test
methods include albumin serum, blood, yeast and yeast extract.
In practice, with exception of a few situations (e.g., clean rooms) the
presence of soiling on surfaces or in liquids to be disinfected can not be
ruled out. For this reason, a small amount of interfering substance should
always be added in testing the product. In the CEN methods this is called
"under clean conditions". Tests under clean conditions can be used
when the surface is clean before disinfection. When a product claims combined
cleaning and disinfection the product should be tested under dirty conditions.
When a product is to be recommended for certain uses where the soiling
is of a specific type (such as soap film residue or hard water scum), the
product must be tested in the presence of that specific soil.
Generally, soiling will reduce the efficacy of the disinfectant, and
where soiling is present, longer contact times, higher concentrations,
pre-cleaning or a combination of these elements may be necessary.
1.4.4.4 Temperature
Generally, disinfection performance increases with temperature, although
this depends on the active substances and the effect on individual species may
vary depending on the specific properties. Therefore, the test temperature
should be representative of the intended use of the product (e.g. low
temperature in stables, high temperature in contact with skin).
1.4.4.5 Contact Time
The contact time of a product on a surface etc. is an important aspect
in the evaluation of the efficacy of disinfectants. In general, the longer the
contact time, the more effective the disinfectant is.
In trials where test organisms are taken from treated samples for further
analysis, the contact time between the biocide and the test organisms should be
stopped. Neutralisers, membrane filtration or subculture techniques are used to
prevent residual carry over of active substances. Neutralisation is discussed
further in section 1.4.4.6 below.
Some disinfectants act very quickly, whereas others require an extended
contact time to achieve adequate performance. Mycobacteria, bacterial spores,
fungal spores and non-enveloped viruses take longer to be irreversibly
inactivated than most vegetative micro-organisms.
The contact time that is practical in real life use should be taken into
consideration when testing. In phase 2 and phase 3 tests the product should
pass the test at the contact time recommended on the product label.
1.4.4.6 Neutralisation
Neutralisers are used to stop the product’s activity in trials where the
test organisms are taken from treated samples for further analysis, such as
plate count following biocidal treatment. An effective neutraliser for the test
product should be identified, and evidence demonstrating the effectiveness of
the neutraliser against the active ingredient, and showing that the neutraliser
itself does not have antimicrobial activity, must be included in a test report.
Appropriate controls for determining the efficacy of the neutraliser should be
performed.
Membrane filtration or subculture techniques can be used to neutralise
the product’s activity, in combination with or instead of chemical
neutralisation.
1.4.4.7 pH
The prevailing degree of acidity or alkalinity during disinfection can
also affect the performance and choice of disinfectant, and must be included in
the test report.
1.4.4.8 Texture of Surfaces
Smooth impervious surfaces are easier to disinfect (and also to clean) than
rough or pitted ones. In some circumstances the micro-organisms might be
protected from the action of disinfectants by being protected in porous
surfaces. Clumps of micro-organisms may also be more difficult to inactivate,
as cells inside are protected by dead micro-organisms on the outside.
Bacteria and fungi can adhere to surfaces forming biofilms. In biofilms,
the cell resistance is increased (the bacteria are in a different physical
state) and penetration of biocide can be difficult to achieve due to the matrix
surrounding the bacteria. This makes bacteria in biofilm more difficult to
inactivate.
The topic of resistance is discussed in the
general part of the TNsG on Product Evaluation (Chapter 6). Additionally, in
support of the review for each active substance information on resistance is
given in the Competent Authority Report of this active substance.
Resistance will be assessed on the basis of expert judgement.
The Biocides Product Directive 98/8/EC (Annex VI 90-93) and Biocidal
Product Regulation 528/2012 (Annex VI) stipulates rules for decision making for
biocides (see Biocides chapter Efficacy General).
The test results shall meet the requirements of the standards or other
criteria for acceptance which are described below per type of use. Where a
product does not perform to these criteria, the applicant should provide a
justification in the application as to why the product should still be
recommended for authorisation.
The CA assessor/expert assesses the performance
of the product as demonstrated in the submitted efficacy tests against the
label claims made for the product and the above criteria. If the product is
judged to be sufficiently effective in laboratory (and, where relevant, field)
tests, the product will be recommended for authorisation as far as efficacy is
concerned.
In exceptional cases the applicant can provide justification why the
specified acceptance criteria are not met but the product is still acceptable.
The Competent Authority will evaluate the justification on a case by case
basis, possibly in consultation with the other Competent Authorities, and
decide whether it is acceptable or not.
The following sections give more specific dossier requirements per type
of disinfectant.
Will be
added later.
Product type 2 contains disinfectants and algaecides not intended for direct application to
humans or animals. This includes inter alia:
-
products
used for the disinfection of surfaces, materials, equipment and furniture which
are not used for direct contact with food or feeding stuffs,
-
usage
areas like swimming pools, aquariums, bathing and other waters;
air-conditioning systems; and walls and floors in private, public, and
industrial areas and in other areas for professional activities.
-
products
used for disinfection of air, water not used for human or animal
consumption, chemical toilets, waste water, hospital waste and soil.
-
products
used as algaecides for treatment of swimming pools, aquariums and other waters
and for remedial treatment of construction materials.
-
products
used to be incorporated in textiles, tissues, masks, paints and other articles
or materials with the purpose of producing treated articles with disinfecting
properties.
The data requirements (test
standards and test organisms) and assessment criteria for the most common uses
are specified below. A detailed but non-exhaustive list of most relevant
product applications and uses of disinfectants within PT2, together with the
relevant test methodologies is given in Appendix 2 (Claims matrix).
All of the possible uses in this PT
cannot be covered in the Appendix. For less common uses, there is often no
international standard test available. Where this is the case, the applicant
should provide tests that show the efficacy of the product and a justification
for the use of these tests. The assessment of these products will be based on
expert judgement and will be handled case by case.
There are some general data requirements which apply to all uses in PT2,
and these are described below. There are also specific data requirements which
apply to different types of use, and these are described in the sections
covering those uses.
The intended uses of the disinfectant determine which tests will be
required to support the product. Tests which most closely reproduce the
practical application conditions should be selected.
In general it is not known which organisms are present on a surface or
matrix to be disinfected. Therefore a disinfectant must have a broad spectrum
of activity, in order to control all of the organisms which may be present.
For general applications in the medical sector, products should be at
least sufficiently effective against bacteria and yeasts (which are responsible
for most common nosocomial infections). Additionally efficacy against other
organisms can be claimed.
If the product is to be used on tuberculosis departments, the product
should be efficacious as general disinfectant used in health care (efficacy
against bacteria and yeast), but efficacy against mycobacteria (representative
for M. tuberculosis) must also be demonstrated.
Products against viruses must be effective against viruses with and
without an “envelope” (protein or lipid mantle). Products can claim virucidal
efficacy if efficacy against non-enveloped viruses has been proven. Such
products can be regarded as efficacious against enveloped and non-enveloped
viruses.
The virus test EN13610, which is recommended in EN14885 for food,
domestic and industrial areas, is not relevant for use in domestic areas, as it
only tests on phages. Instead, the test specified for the medical area,
EN14476, should be used for products against viruses used in domestic areas.
For biocidal products with a biostatic effect (bacteriostatic,
fungistatic, etc.), both suspension and surface tests should be performed. The
suspension test should be performed with and without neutralisation. The
results from this test should show that the product prevents growth of the test
organism (a reduction in numbers compared to the negative control) but does not
kill them (survival of the test organism in the test without neutralisation).
There are specific requirements for products claiming control of
organisms which cause malodour. Phase 2/step1 and step 2 tests should be
performed with odour producing micro-organisms. A justification for which
bacteria, fungi, etc. are relevant to the intended use should be provided. Next
to these laboratory tests an odour test can be performed.
Tests (phase 2, step 1) should be carried out at a range of concentrations
in order to verify that the use concentration is suitable for the desired
effect (e.g. not too high or not at the minimum effective level).
When small changes are made to the non-active ingredients in a product,
it is not always necessary to redo all the tests with the new formulation. The
applicant may provide a justification for changes and the effects they have on
the efficacy of the product. In case of a minor change, a robust justification
might be sufficient (to be decided by the Competent Authority). In other cases,
new efficacy tests will have to be provided. This can be a full set of efficacy
tests or a test with the most resistant organism in the former test.
Biocides can
be used to disinfect hard surfaces in areas such as hospitals, industry,
institutions or private homes. These surfaces can be tables, floors, walls, the
outsides of machinery and hard furniture, etc.. Products are often wiped or
sprayed onto the surfaces, and may be washed or wiped off after a certain
contact time.
The testing
requirements for some specific uses of hard surface disinfectants are discussed
in separate sections e.g. toilets, room disinfection with vaporised biocide,
immersion of equipment into the product, etc.. As the areas of use can be as
diverse as private homes, operating theatres etc., the test requirements might
vary depending on the area of use.
See general data requirements PT2 (section 3.2). A detailed, but
non-exhaustive list of most relevant product applications and uses of hard
surface disinfectants and the required test methodologies is given in Appendix
2 (Claims matrix, table Hard surfaces).
3.3.2.1 Test methods
For efficacy testing of hard surface disinfectants, the tiered approach
as described in section 1.4.1 is preferred.
The following tests are normally required for a
hard surface disinfectant:
-
a
quantitative suspension test (phase 2/step 1),
-
and
a quantitative surface test (phase 2/step 2),
both simulating practical conditions appropriate to its intended use
(temperature, soiling, different surfaces, contact time, etc.).
Tests in phase 3 are optional, as no validated test methods are
available yet.
Several test methods for testing the efficacy of hard surface
disinfectants are available.
Appendix 3 gives a list of recommended test methods.
The following documents are recommended for surface disinfection:
·
EN
14885: gives an overview of which EN phase2/step1 and step2 tests to use for different
uses.
·
OECD
guidance and guidelines for the testing of chemicals: Quantitative method for
evaluating activity of microbiocides used on hard non-porous surfaces. (These
are surface tests which would be considered phase 2/step 2 tests)
The use of the specified tests is strongly recommended where they are
relevant and appropriate. Where the tests are not appropriate to the product
other tests can be used, although a justification for the relevance of the
tests used should also be provided.
Preferably, tests should be selected that correspond to the use area of
the product (e.g. tests from medical area for use in hospitals and tests for
industrial areas for use in cosmetic industry). Where the product is intended
for use in several areas it is acceptable to perform the tests specified for
only one of the areas, as long as the test with the highest/most stringent pass
criteria is used.
A phase 2/step 2 surface test is not yet available for the medical
sector. However the surface test for the food/industrial sector can be used,
with medical area specific soiling, instead.
Currently only validated surface tests without mechanical action are
available (EN and OECD). Validated surface tests with mechanical action are
being developed, and should be used for products that are intended to be used
with mechanical action when they are available.
Where specific conditions apply for a field of use, such as high/low
level soiling, high/low temperatures, relevant contact times etc. (see
introduction 1.4.4), these conditions should be included in the efficacy
testing.
Disinfectant towels/wipes
For disinfectant towels, the phase 2/1 tests should be done with liquid
extracted from the towel. Phase 2/2 tests should be tests with mechanical
action (CEN in preparation). Until these tests are available, surface tests can
be done with liquid extracted from the towel, although a justification of the
volume that is applied per square centimetre will also be required. In
additional, a test has to be performed that shows that either the towel will
still disinfect if the towel dries out or that the towel stays wet long enough
to disinfect according to the claim. Alternatively, the use directions can
address these issues, for instance, stating on the label that only wet towels
are efficacious, defining the surface area each towel can disinfect (e.g. 0.5 m2),
or giving expiry dates for resealable packages.
3.3.2.2 Test organisms
The test organisms used in efficacy tests are normally stated in the
applicable standard test methods.
If standard tests are not used (there will normally need to be a
justification for this), the test organisms used to support a general claim
should be demonstrated to be equivalent to the reference organisms given in
Appendix 4.
Tests with test organisms other than those mentioned in Appendix 4 are
acceptable, if adequate scientific evidence is submitted on which the relevance
of the test organism to the field of use can be judged.
Also see the general data requirements PT2 for specific claims and minimum
requirements in health care.
A product will be assessed to be
sufficiently effective if the required laboratory and, where relevant, field
tests have been carried out (using the required test organisms and test
conditions), and when the pass criteria for the tests have been met.
Where pass criteria are available in the standard test these should be
met.
If the test doesn’t provide these criteria, the general criteria in
Appendix 5 can be taken as guidance for the level of reduction required.
Deviations from the pass criteria are possible, but must be justified in the
application. The Competent Authority will evaluate any justification on a case
by case basis, consulting the other Competent Authorities where appropriate,
and decide whether it is acceptable or not.
Disinfectants for use on soft furnishings are
intended to be used on fabrics in the home, institutional environment, healthcare
and healthcare facilities. These can be used to treat porous soft surfaces such
as curtains, sofas, upholstery, mattresses and carpets. The products are often
sprayed onto the surfaces.
See PT2 general data requirements. A
detailed, but non-exhaustive list of most relevant product applications and
uses of hard surface disinfectants and the required test methodology is given
in Appendix 2 (Claims matrix, table “Soft furnishings”).
3.4.2.1 Test methods
For efficacy testing of surface disinfectants for use on soft furnishing
the tiered approach as described in section 1.4.1 is preferred.
The following tests are normally required for a
these surface disinfectant:
-
a
quantitative suspension test (phase 2/step 1),
-
and
a quantitative surface test (phase 2/step 2),
both simulating practical conditions appropriate to its intended use
(temperature, soiling, different surfaces, contact time, etc.).
Tests in phase 3 are optional as no validated test methods are available
yet.
Where possible, the phase 2 step 1 test should
be selected from EN14885 from the table that corresponds to the use area of the
product (e.g. test from medical area for use in hospitals and test for domestic
areas for use in private homes). In case the product is intended for several
areas, it is acceptable to perform the tests from only one area, as long as the
test with the highest pass criteria is used.
For the phase 2 step 2 test it is suggested
that EN13697 be modified to include suitable fabric types in place of the
standard stainless steel carriers. ISO 20743 can also be used, or other
quantitative methods including textile as carrier.
3.4.2.2 Test organisms
The same test organisms as given for hard surfaces should be tested. See
section 3.3.2.2 and Appendix 4.
A product will be assessed to be sufficiently effective if the required
laboratory and, where relevant, field tests have been carried out (using the
required test organisms and test conditions), and when the pass criteria for
the tests have been met.
Where pass criteria are available in the standard tests these should be
met.
If the test doesn’t provide these criteria, the general criteria in
Appendix 5 can be taken as guidance for the level of reduction required.
Deviations from the pass criteria are possible, but must be justified in the
application. The Competent Authority will evaluate any justification on a case
by case basis, consulting the other Competent Authorities where appropriate,
and decide whether it is acceptable or not.
Room disinfection involves the reduction and inactivation of
micro-organisms on the surfaces of the walls, floor and ceiling of the room, as
well as on external surfaces of the furniture and equipment present in the
treated room. The product is applied by airborne diffusion of an aerosol, a
smoke, a vapour or a gas. The technical characteristics of the diffuser
equipment play a central role, ensuring an homogeneous distribution of the
biocide product in the volume of the room and reaching all surfaces (including
ceilings and the undersides of horizontal surfaces), therefore the diffuser
equipment contributes in a decisive way to the efficacy of the product. Manual
spraying is not covered in this section, but under hard surface disinfection
(section 3.3).
Room disinfection may not disinfect the inside parts of furniture, and
will not disinfect the air itself, so these uses are not considered in this
chapter. Room disinfection is therefore closely related to surface disinfection
without mechanical action. As this causes complications in cases of organic
contamination, cleaning of surfaces is necessary prior to room disinfection.
3.5.1.1 Process:
The application of the product consists of four phases:
(1) The preparation phase (required depending on type of active
substance and application procedure), during which the environmental conditions
(relative humidity, temperature) are modified to an optimal level for the
product,
(2) The conditioning phase, during which the product is diffused into
the room, in order to reach the desired effective concentration,
(3) The disinfection phase, which corresponds to the contact time
required to obtain the expected level of efficacy, and
(4) The terminal phase, which includes aeration of the room to remove
any disinfectant present in the air, or other procedures for inactivation of
the active substance, before access of people or animals into the room can be
permitted (figure 5.1).
Particular
attention must given to the dispersal time and contact time. The dispersal time
is the time necessary to reach a target concentration of the product on the
surfaces to be disinfected in a given volume, while the contact time is the
time necessary to reach the expected efficacy.
Note: the
various phases of the cycle presented are theoretical and can be adapted
according to the process. The maintenance of a concentration of biocide in the
atmosphere may be achieved by the regular introduction of additional biocide
during the contact phase.
Airborne disinfection differs from direct application of liquids to
surfaces. Therefore the EN phase 2/ step 2 standards for surface disinfection
are not applicable for room disinfection. The tiered approach is still
possible, however, by using different test methods.
The following tests are normally required for a
room disinfectants:
-
when
applicable a quantitative suspension test (phase 2/step 1),
-
semi-field
trial such as NF T 72-281 or European standard (EN standard in preparation) for
disinfection using airborne application (phase 2/step 2).
The CEN phase 2/step 1 tests are suitable as suspension tests under
clean or dirty conditions, although only applicable for products that can be
tested in suspension (e.g. not for gasses). These tests are not sufficient on
their own, and should be combined with a semi-field trial, such as NF T 72-281
for disinfection using airborne application. Where it is not possible to test
the product in a suspension test, the semi-field trial will be sufficient.
NF T 72-281 was developed by AFNOR (the French standardisation body) in
1986, updated in 2009, and proposed as new item within the framework of TC 216
in November 2010. This semi-field method evaluates the efficacy of
disinfectants when vaporised in a room (automatic diffusion process) or when
sprayed into the direction of a surface (manual application). Only application
by vaporisation is discussed in this section. Once this method has been
finalised and adopted at European level, any method variations should be taken
into account.
Inert and dry carriers infected with a known number of micro-organisms (bacteria,
yeast, fungi or bacterial spores) are placed in a room of defined volume,
temperature and relative humidity. The size of the test room should be relevant
to the claims for the product. The carriers used are often stainless steel, but
other relevant (generally non-porous) materials can also be used, for instance,
glass, filter paper, or plastic.
When the disinfection of textiles (curtains etc.) and other materials
(e.g. wallpaper. filters in flow cabinets, etc.) is claimed, appropriate
carriers should be used to demonstrate efficacy.
The standard NF T 72-281 does not include tests against viruses.
Inoculation of carriers with viruses according to the protocols of CEN or OECD
surface tests and exposure to the airborne disinfection process as according NF
T 72-281 is acceptable.
The inoculated carriers must be placed in a vertical position with
inocula facing away from the diffuser. Their distance to diffuser depends on
the room dimensions (for instance: see Appendix B of NF T 72-281). The test
method defines obligatory conditions for parameters that may influence the
success of the disinfection.
This test includes the use of milk as interfering substances in order to
maintain viability of the micro-organisms on the carriers during the test.
Depending on the area of use, other suitable interfering substances should be
tested (e.g. blood for use in hospitals).
Similar carriers are placed in a second room nearby, which is not
treated with diffused product, as controls.
Additional tests can be performed to simulate specific conditions that
are encountered in the practice and to fit with label instructions. In that
case, all experimental conditions should be clearly described in the test
reports. The standard lists the information that must be included in the final
report.
As mentioned earlier, the disinfection efficacy is closely related to
the technical characteristics of the diffuser. Chapter 5 “intended uses and
efficacy” of the “Guidance on data requirements for active substances and biocide
products” requires applicants to take into account the technical equipment used
together with the product to be authorised.
A detailed description of the equipment and its characteristics must be
provided in sufficient detail to distinguish it from other equipment:
Ø
equipment
name and model,
Ø
diffusion
principles (fogging, vapour, fumigation, …) and particles size distribution of
aerosols or powder,
Ø
description
of the diffusion performance of the equipment (volume to disinfect, diffusion
speed…),
Ø
description
of the ambient conditions (humidity, temperature, …) in which the process can
be used,
Ø
diffusion
time for a specific volume
Ø
precautions
for over- and under-dosing.
The product authorisation will only be granted for use with the
equipment described in the application. After authorisation, any modification
to the equipment should be validated and reported to the Competent Authority
for evaluation.
For major modifications which can affect the efficacy (pipe, pump,
nozzles…), it should be demonstrated that the efficacy of the process has not
been affected (for example: by a new study on the most resistant organism).
For minor modifications which do not change the efficacy of the process,
only a notification of the modifications to the equipment must be provided.
3.5.2.1.3
Contact time
As room disinfection may necessitate a long period of treatment, the
contact time to be tested is not defined. The testing should demonstrate
efficacy at contact time proposed for the intended use. This should be relevant
to practical use and depends on substance concentration, volume of room, power
of the diffuser equipment, etc... All of these parameters should be stated on
the product label or in a technical information sheet.
Since room diffusion is used to disinfect hard (and soft) surfaces the
same organisms should be tested as for hard surface disinfection (section 3.3).
Appendix 4 contains a table of reference organisms.
The general data requirements for PT2 for specific claims and minimal
requirements in health care also apply for room disinfection with vaporised
biocide.
A product will be assessed to be sufficiently effective if the required
laboratory and, where relevant, field tests have been carried out (using the
required test organisms and test conditions), and when the pass criteria for
the tests have been met.
Where pass criteria are available in the standard tests these should be
met.
If the test doesn’t provide these criteria, the general criteria in
Appendix 5 can be taken as guidance for the level of reduction required.
Deviations from the pass criteria are possible, but must be justified in the
application. The Competent Authority will evaluate any justification on a case
by case basis, consulting the other Competent Authorities where appropriate,
and decide whether it is acceptable or not.
3.5.4.1 Limitations
Any limitations of the procedure should be specified in the application.
Literature has shown that disinfection by vaporised biocide may not be
as effective on wet surfaces (lower concentration of the product) or inside
closed cupboards and closets (where the vapour cannot penetrate). Therefore
carriers should be tested under these conditions, and if efficacy is not
proven, the label instructions should provide appropriate information (such as
stating that cupboard doors should be opened, surfaces should be dried and wet
areas (such as sinks and toilet bowls) should be disinfected with suitable
alternative products.
Other factors which may influence the efficacy of the process in the
practical use (such as the equipment, furniture, special structures (e.g. bumps
on the walls) or special materials (copper in hydrogen peroxide procedures)
including environmental conditions (e.g. temperature, relative humidity) which
may affect the success of the disinfection have also to be considered. The
conditions of a sufficient vaporisation should also be specified.
Disinfectants can be used to disinfect water in swimming pools, spas and
hot tubs. These may be public pools (which may be used by many people daily) or
household pools or tubs (which might be used only occasionally). An
intermediate situation consists of facilities in hotels, housing complexes or
sports clubs, where the bather load may be lower than in a fully public
facility, but still high compared to private, domestic facilities.
Disinfectant products can be added to a pool continuously,
intermittently, by shock dosing or through generation in situ. Large public
facilities may have dedicated staff to maintain the pool using automated
control systems, whereas smaller pools may be treated using manual methods by
janitorial staff. Private pools may be treated by individual householders, supplemented
in some cases by professional pool treatment personnel. Disinfection is only
one aspect of pool maintenance and other activities, such as ensuring the
correct pH and the removal of pollutants by oxidation, flocculation and
filtration, are essential to ensure adequate water quality.
The principal purpose of disinfection is to disinfect the water to
prevent the water-borne transmission of pathogens between pool users.
Supplementary purposes are to ensure the aesthetic quality of a pool (by ensuring
that algae do not result in turbid water or unsightly microbial growth on pool
surfaces, such as the floor and walls of the pool) and to prevent microbial
slime and biofilm formation in pipework and related equipment.
This section only deals with disinfection of the pool water and the
pipework and related equipment containing pool water. The disinfection of hard
surfaces surrounding the pool is covered in section 3.3.
See PT2 general data requirements.
A detailed, non-exhaustive list of the most relevant applications and of
appropriate test methodology is given in Appendix 2 (Claims matrix, table
“Swimming pools”).
For efficacy testing of pool disinfectants the tiered approach as described
in section 1.4.1 is preferred.
The following tests are normally required for a
pool disinfectant following a tiered approach:
-
a
quantitative suspension test (phase 2/step 1),
-
simulated-use
tests with pool water or a surface test (phase 2/step 2)*
-
and
a field test (phase 3)**,
all simulating practical conditions appropriate to its intended use
(temperature, contact time, soiling/bather load etc.).
* A phase 2/step 2 test may be
appropriate in cases where a product has a specific use in surface
disinfection. Otherwise, a simulated use test is appropriate for products
intended to disinfect the water in a pool or spa.
** In some cases the field trial
can be waived. The OECD guidance document (described below) is based on
experience with hypochlorous acid/hypochlorite. Therefore, it is acceptable
that for products based on hypochlorous acid/ hypochlorite the field test is
waived and only laboratory test data are provided. In some other cases, waiving
the phase 3 test can also be justified.
The OECD ”Guidance Document for Demonstrating Efficacy of Pool and Spa
Disinfectants in Laboratory and Field testing” (OECD Series of Testing and
Assessment No 170, version dated 08 October 2012) describes laboratory and
field test methods, conditions and criteria needed to demonstrate efficacy of a
pool disinfectant. The protocol for field tests should be agreed between the
applicant and Competent Authority before a field test is initiated.
For products that are used for specific purposes such as disinfecting pipework,
filters and filter media, it may be more appropriate to test using the EN 14885
methods for the disinfection of surfaces in institutional applications.
3.6.2.2 Test organisms
Besides bacteria and viruses, protozoa can also be of importance in
swimming pools. Fungi may pose a health hazard on wet surfaces surrounding the
pool and can cause slime build up in pipework. Table 6.1 lists the organisms
that normally should be tested. Although algae and protozoa in pools are in
general only a problem when maintenance of the pool is not carried out
properly, data against algae and/or protozoa should be provided where claims
against these targets are made.
A product will be assessed to be sufficiently effective if the required laboratory
and, where relevant, field tests have been carried out (using the required test
organisms and test conditions), and when the pass criteria for the tests have
been met.
When pass criteria are available in the standard tests these should be
met.
The OECD guidance document sets out criteria for laboratory and field
tests. Table 6.1 and 6.2 show these default criteria.
Table 6.1 Criteria for laboratory tests
Test Organisms for both swimming & spa pools
|
Number of log10 reductions to be achieved
|
Time of exposure to test disinfectant at normal
concentration during which reduction is to be achieved
|
Bacteria
|
Escherichia coli
|
4
|
30 seconds
|
Enterococcus faecium
|
4
|
2 minutes
|
Pseudomonas aeruginosa
|
4
|
30 seconds
|
Legionella pneumophila
|
4
|
30 seconds
|
Staphylococcus aureus
|
4
|
30 seconds
|
Viruses a
|
Adenovirus (disaggregated) b
|
3
|
10 minutes
|
Rotavirus (disaggregated) b
|
3
|
2 minutes
|
Protozoa c
|
Naegleria fowleri - (cysts)
|
4
|
30 minutes
|
cGiardia intestinalis d or Giardia muris e - (cysts)
|
3
|
45 minutes
|
Algae
|
None specified f
|
|
|
a Among viruses, Enterovirus can be
added to the above list, but the performance characteristics against free
chlorine are not known.
b Prior to the test exposure, virus
suspensions should be treated to disassociate aggregated clusters of virus
particles
c Among protozoa, Cryptosporidium can
be added to the above list, but the performance characteristics against free
chlorine are not known
d Giardia intestinalis is the human
pathogen – in the literature this species may also be referred to as Gardia
lamblia and the more general mammal parasite Giardia duodenalis.
e The rodent pathogen Giardia muris can
be used as a surrogate for the human pathogen
f There are no European or international
standardised test methods for activity against algae; species selected should
be representative of those that require control. Algaecidal properties are not
covered by the OECD guidance document
Table 6.2. Criteria for field tests
Test Organisms
|
Test Method
|
Maximum Count Allowable
|
Culturable micro-organisms colony count (also called
„aerobic” colony count or „heterotrophic” colony count)
|
ISO 6222:1999 – Enumeration of culturable
micro-organisms – Colony count by inoculation in a nutrient agar culture
medium.
|
100 Colony Forming Units (CFU) per ml
|
Thermotolerant coliforms
|
ISO 9308-1 – Detection and enumeration of E. Coli
and coliforms – Part 2: Membrane filtration method.
|
Not detectable in 100 ml
|
Pseudomonas aeruginosa
|
ISO 16266 – Detection and enumeration of Pseudomonas
aeruginosa – Method by membrane filtration.
|
Not detectable in 100 ml
|
Where these criteria are not met, the applicant can provide a
justification as to why the product should still be considered acceptable.
However, the Competent Authority will evaluate any justifications on a
case-by-case basis, consulting the other Competent Authorities as necessary,
and will decide whether it is acceptable or not.
The OECD guidance document contains more details on factors to be
considered.
Biocides can
be used to disinfect toilet bowl surfaces in diverse environments including;
hospitals, industry, institutions or households. Toilet bowl biocides are
available in a wide variety of forms, including liquids, foams, powders, and
tablets. These products are often applied via pouring around the inside rim of
the toilet bowl surfaces, with the area scrubbed after a minimum contact time.
Toilet rim block biocides are used in flush toilets, are attached over
the rim of a toilet, hanging down into the bowl. The block slowly dissolves in
water as the toilet gets flushed. These biocides also come loose for placement
directly in the cistern (water reservoir), and these variants usually dissolve
slower with the constant contact with water.
Hard surfaces on the inside of toilets are covered by this section.
Surfaces on the outside and toilet seats, lids etc. are covered by section 3.3
“hard surfaces”.
The use of biocides in chemical toilets, most commonly found on
airplanes, trains, and in portable toilets is not covered in this section.
See PT2 general data requirements.
A detailed, non-exhaustive list of the most relevant applications and of
appropriate test methodology for is given in Appendix 2 (Claims matrix, table
“Toilet bowls”).
3.7.2.1 Test methods
For efficacy testing of toilet disinfectants the tiered approach as
described in section 1.4.1 is preferred.
The following tests are normally required for a
hard surface disinfectant:
-
a
quantitative suspension test (phase 2/step 1),
-
and
a quantitative surface test (phase 2/step 2),
both simulating practical conditions appropriate to its intended use
(temperature, soiling, contact time, etc.).
Several test methods for quantitative suspension and surface tests are
available.
Appendix 3 gives a list of recommended test methods. The following
documents are recommended for surface disinfection:
·
EN
14885: gives an overview of what EN phase2/step1 and step2 test to use for
different uses.
·
OECD
guidance and guidelines for the testing of chemicals: Quantitative method for
evaluating activity of microbiocides used on hard non-porous surfaces. These
are surface tests which would be considered phase 2/step 2 tests.
The use of the specified tests is strongly recommended where they are
relevant and appropriate. Where tests are not appropriate to the product other
tests can be used, although a justification for the relevance of the tests used
should also be provided.
For products intended to be added to the water reservoir or hanging down
from to the rim of the bowl, the concentration of the product (or at least the
active substance) in the water before, in between and after flushing should be
determined. This can be done by an analysis of the water under in-use
conditions or, for products were all parameters are defined, by calculation.
The laboratory efficacy tests should be performed with these concentrations.
Tests in phase 3 are optional.
3.7.2.2 Test organisms
The same test organisms as for hard surfaces should be tested. See
section 3.3.2.2 and Appendix 4.
Fungi are not relevant to target in toilets, so products will normally
only target bacteria and yeasts (and optionally viruses).
A product will be assessed to be sufficiently effective if the required
laboratory and, where relevant, field tests have been carried out (using the
required test organisms and test conditions), and when the pass criteria for
the tests have been met.
Where pass criteria are available in the standard tests these should be
met.
If the test doesn’t provide these criteria, the general criteria in
Appendix 5 can be taken as guidance for the level of reduction required.
Deviations from the pass criteria are possible, but must be justified in the
application. The Competent Authority will evaluate any justification on a case
by case basis, consulting the other Competent Authorities where appropriate,
and decide whether it is acceptable or not.
Disinfection
of air-conditioning systems is similar to hard surface disinfection since only
the surfaces in the system are disinfected and not the air itself. The
difference with general surface disinfection is that the surfaces are mostly
hidden inside the system and cannot be reached easily without taking it apart
(for instance for air-conditioning systems in cars, dismantling the system
would not be desirable).
In general
disinfectants for air-conditioning systems are applied by airborne diffusion of
an aerosol, a smoke, a vapour or a gas. The biocide is applied to an operating
air-conditioning system at the inlet of the system. This way the biocide is
sucked into and passes through the whole system.
Preservation
of cooling liquids is not covered under PT2 but rather within PT11
(preservatives for liquid cooling and processing systems).
3.8.1.1 Data requirements
For products that are applied by airborne diffusion of an aerosol, smoke,
vapour or gas the same test methods and test organisms should be used as for
room disinfection. Therefore, the same data requirements as for section 3.5
(Room disinfection with vaporised biocide) are applicable here.
The following tests are normally required for a disinfectant for air-conditioning
systems:
-
when
applicable a quantitative suspension test (phase 2/step 1),
-
semi-field
trial such as NF T 72-281 for disinfection using airborne application (phase
2/step 2).
See section 3.5 for specifications.
In the semi-field test the carriers with test organisms are placed in
the air-conditioning system at the beginning and at the end of the system. When
it is not possible to put carriers in the system they should be between the
biocide application site and the inlet of the system and at the end of the
system, in the out flowing air. If carriers at both sides full fill the
criteria it can be assumed that the surfaces in between are also disinfected
sufficiently.
For products that are applied by manual spray the test methods and test
organisms should be used as for hard surface disinfection. See section 3.3
(Hard surface disinfection) for data requirements.
In addition to these data, the applicant should provide a justification
that the spray apparatus is capable of reaching all (hidden) surfaces of the
air conditioning system.
3.8.2 Acceptance
criteria
A product will be assessed to be sufficiently effective if the required
laboratory and, where relevant, field tests have been carried out (using the
required test organisms and test conditions), and when the pass criteria for
the tests have been met.
The same pass criteria can be used as for other surface disinfection
(section 3.3.3). The criteria in Appendix 5 can be taken as guidance for what
level of log reduction is normally required. Deviations from the norm are
possible, but have to be justified in the application.
Although instrument or equipment disinfection can be considered equal to
hard surface disinfection, it differs from the intended use in section 3.3
because it is mainly applied by immersion of the instruments in the biocide
solution or by filling equipment with the solution (disinfection of inner
surfaces). The products are intended for instruments used in health care
facilities, laboratories and industry.
Some of the products used for disinfection of medical instruments, which
are to be used specifically for diagnostic and/or therapeutic purposes for
human beings, are not under the scope of the BPD. Disinfectants that are
specifically used for disinfection of medical devices or a group of medical
devices (anaesthetic equipment, endoscopes, surgical instruments, incubators)
are covered under the Medical Device Directive 93/42/EEC. However,
disinfectants with a broader claim, e.g. disinfection of instruments and
surfaces, are under the BPD. The BPR states that such biocidal products should
comply, in addition to the requirements laid down in this Regulation, with the
relevant essential requirements set out in Annex I to Council Directive
90/385/EEC of 20 June 1990 on the approximation of the laws of the Member
States relating to active implantable medical devices, Council Directive
93/42/EEC of 14 June 1993 concerning medical devices and Directive 98/79/EC of
the European Parliament and of the Council of 27 October 1998 on in vitro
diagnostic medical devices.
3.9.2.1 Test methods
For efficacy testing of equipment disinfectants the tiered approach as
described in section 1.4.1 is preferred.
The following tests are normally required for a
instrument disinfectant:
-
a
quantitative suspension test (phase 2/step 1),
-
and
a quantitative carrier test (phase 2/step 2),
both simulating practical conditions appropriate to its intended use
(temperature, soiling, different surfaces, contact time, etc.).
Methods for testing efficacy of instrument disinfectants are
available.
Appendix 3 gives a list of recommended test methods. The following
document is recommended for instrument disinfection:
·
EN
14885: gives an overview of which EN phase2/step1 and step2 test to use for
different uses.
The use of the specified tests is strongly recommended where they are relevant
and appropriate.
For use in industry and institutional areas, no specific tests for
instrument disinfection are given in EN14885. While these tests are not
available for the phase 2/step 1, either the surface disinfectants test from
the industry and institutional areas or the instrument tests for medical areas
can be used, by employing area specific soiling. For phase 2/step 2 the
instrument tests for medical areas are most appropriate, also with area
specific soiling.
3.9.2.2 Test organisms
For general disinfection of medical instruments, efficacy against
bacteria, yeasts, viruses and fungi must be demonstrated. For all other uses
the test organisms specified for hard surfaces should be tested. See section
3.3.2.2 and Appendix 4.
A product will be assessed to be sufficiently effective if the required
laboratory and, where relevant, field tests have been carried out (using the
required test organisms and test conditions), and when the pass criteria for
the tests have been met.
Where pass criteria are available in the standard tests these should be
met.
If the test doesn’t provide these criteria, the general criteria in
Appendix 5 can be taken as guidance for the level of reduction required.
Deviations from the pass criteria are possible, but must be justified in the
application. The Competent Authority will evaluate any justification on a case
by case basis, consulting the other Competent Authorities where appropriate,
and decide whether it is acceptable or not.
Biocides can
be used to treat textiles and fabrics in hospitals, health care facilities,
industry, institutions or private homes, when relevant micro-organisms
(pathogenic, spoiling) in the textiles have to be reduced. These products can
be in the form of laundry products which combine detergent and biocide or can
be specialised products in the form of laundry additives which are added to the
wash cycle or as finishing products (e.g. fabric softeners) which are added in
the last rinsing step or as pre-treatment.
Typically
contaminated clothes, linen or other washable textiles are treated in an
appropriate washing machine. The biocide is added in concentrated form and
diluted in the machine with water according to the specification of the
manufacturer to get a defined concentration in the machine. The automated
chemical-thermal process normally comprises an (optional) initial pre-treatment
step for heavily soiled laundry, followed by the main washing step (at a
defined temperature and defined contact time) and 3 to 4 rinsing steps with
cold water.
In some cases
laundry can be treated through a hand-wash process in diluted biocide, which
can be as pre-soak (after which machine washing is used), as a hand wash only,
or through soaking to disinfect textiles before they are destroyed (for
example, in an infectious disease outbreak situation).
Biocidal
laundry products, either as combined biocide/detergent/conditioner or as
special additives, are available for either targeted pre-treatment of
contaminated articles or for whole-wash use.
See PT2 general data requirements. A detailed, non- exhaustive list of
the most relevant applications and of appropriate test methodology for is given
in Appendix 2 (Claims matrix, table Laundry products).
3.10.2.1 Test methods
For efficacy testing of textile disinfectants the tiered approach as
described in section 1.4.1 is preferred.
The following tests are normally required for a
textile disinfectant:
-
a
quantitative suspension test (phase 2/step 1),
-
a
quantitative carrier test involving carriers made of test fabric (cotton,
polyester) (phase 2/step 2),
Both should simulate practical conditions relevant to its intended use
(concentration of the product, temperature, soiling, different fabrics, contact
time, etc.).
At this moment three types of test are available:
- phase 2/step 1 suspension
tests as described in EN14885,
- phase 2/ step 2 tests
involving test fabrics in a small scale laboratory setting (e.g. ASTM E2406) or
a full-scale laundry machine test (as a CEN draft TC 216/N 472, or DGHM).
In the phase 2/step 2 tests fabric is contaminated with test organisms
and then exposed to the disinfectant.
The EN tests are strongly recommended where available and appropriate.
3.10.2.1.1
Test conditions
For products intended to be added to washing machines, information on
the following in-use conditions should be provided:
-
the
concentration of the product (or at least the active substance) in the
water during disinfecting process (i.e. washing or rinsing). The water volume
used can differ between wash and rinse cycle and different washing programmes,
but also between washing machines
-
the
water to textile ratio in the test is an important factor that should reflect
the in-use conditions
-
the
temperature during the disinfection process (high when added in wash process,
low in rinse process)
-
the
contact time (differs between various washing programmes and washing
machines)
The laboratory tests should be performed under
these conditions. The identified conditions of effective disinfection can
normally only be carried out in professional washing machines.
If the exact conditions cannot be met, e.g. in household machines,
reasonable worst case conditions shall be tested.
Worst case conditions:
-
the
lowest temperature
-
the
highest volume of water (i.e. maximum dilution of the product)
-
the
shortest contact time
-
the
maximum load of laundry (i.e. smallest water to textile ratio).
When phase 2, step 2 tests involving fabric test carriers are performed,
both the micro-organisms remaining on the test carriers, those released into
the washing liquid and those transferred to previously uncontaminated control
carriers should be assessed.
Manual soaking or pre-soaking can be done at room temperature but for some
intended uses the temperature might start high and will cool down during the
contact time (e.g. where hot water is used, which cools naturally). This should
also be taken into account in the tests.
3.10.2.1.2
Soiling:
The interfering substance most appropriate for
the in-use conditions should be used. For instance, blood for products used in
the medical area and protein for products used in industry, institutional and
domestic areas is recommended. The soiling on a domestic product for use in
pre-soak (dirty clothes) will be very higher than the soil for a post-wash
rinse additive (clean clothes). For products used during pre-soak and wash
tests should be done under dirty conditions. For products used during post-wash
rinse test should be done under clean conditions.
A product will be assessed to be sufficiently effective if the required
laboratory and, where relevant, field tests have been carried out (using the
required test organisms and test conditions), and when the pass criteria for
the tests have been met.
EN and DGMH tests provide pass criteria.
No acceptance criteria have been specified in the ASTM standards for
laundry (ASTM E 2406-04).
If the test doesn’t provide pass criteria, the general criteria in
Appendix 5 can be taken as guidance for the level of reduction required.
Deviations from the pass criteria are possible, but must be justified in the
application. The Competent Authority will evaluate any justification on a case
by case basis, consulting the other Competent Authorities where appropriate,
and decide whether it is acceptable or not.
A biofilm is a complex aggregation of micro-organisms distinguished by
the excretion of a protective and adhesive matrix attached to a solid surface
in contact with a fluid. The matrix may incorporate other components derived
from the environment.
Once the first cell succeeds to attach to the solid surface and biofilm
starts to form, growth of the biofilm may become very fast, as subsequent free
floating bacteria find it much easier to attach to the developing matrix.
Biofilms can grow in areas such as inside water tanks and distribution
pipelines of hospitals, hotels, industries and in general in all those water
systems which have adequate temperature and nutrients for the microbial growth.
The consequences of biofilm formation into a water system or facility
may be severe depending on environmental conditions and any safety and
performance requirements.
In healthcare facilities, biofilm contamination of medical equipment or
water systems may increase the risk of nosocomial infections; in industrial
facilities biofilm may cause microbial contamination of production
(pharmaceuticals, cosmetics, etc.); in other situations biofilms may be
responsible for significant reduction of the performance of water systems by
obstructing normal water flow or they may induce corrosion of the pipelines.
Several factors may contribute to biofilm formation, with important factors
including the chemical composition and roughness characteristics of the pipe,
tank or tube circuit.
Bacteria in biofilms are more resistant to disinfection than free
floating bacteria of the same species, as the presence of extracellular
polymeric substances acts as a physical barrier to the biocide. This matrix may
hamper biocidal penetration to the lower layers of the biofilm or may interact
with the biocide and neutralise it. Additionally, the physiological state of
the bacteria in the biofilm differs from bacteria in suspension, which can also
influence the susceptibility of the bacteria to biocides.
Two types of activities of biocides against biofilm can be identified:
a) Prevention of biofilm
formation: the biocide acts on biofilm formation (i.e. in this case the biocide
is present before the biofilm is formed and may affect the early adhesion of
cells to the surface or the viability of the cells).
b) Biofilm disinfection
(“curative”): the biocide acts on a mature biofilm (i.e. when the biofilm is
already present on a surface and the biocide interacts with the
biofilm-embedded cells, with a -cidal effect). Biocidal products of this type
may also achieve detachment of the biofilm (possibly in conjunction with
physical action).
In case where the biofilm is not removed as a result of the biocide
treatment, it should be followed by mechanical removal of the biofilm.
Industry is increasingly developing new technologies for prevention,
inactivation and/or detachment of biofilms and/or inactivation of biofilm
embedded organisms, for example through the use of UV light, water ionization
or impregnated or coated materials and new biocides which claim specific
efficacy against biofilms.
There are currently no standard laboratory tests available to verify the
efficacy of biocides against biofilms. As this is an area in which the science is developing rapidly, the
information below should be considered as general guidance reflecting the state
of knowledge at the time of writing.
Tests to demonstrate the efficacy of disinfectants according to EN and
OECD are based on simpler models than are found in biofilms. The available
surface/carrier tests are not representative of biofilm models, as they do not
consider the presence of extra cellular polymeric substances which act as a
physical barrier to the biocide.
Other characteristics of the biofilm and biocidal product should be
taken into account. For example, if biocide impregnated materials claim a
preventive effect on biofilm formation, the prevention of biofilm formation
should be demonstrated, taking into consideration the half-life of the
impregnating substance which may differ depending on the material
characteristics. The active substance may be released from the surface and/or
may be inactivated by environmental factors.
A standard suspension test can only be used to confirm basic activity of
the product against the claimed organisms in a tiered approach.
A suggested general approach could be:
1) a
suspension test: any biocide claiming to act on biofilm, has to be first
evaluated in standard suspension test (preferably EN)
2) a
simulated use efficacy test to demonstrate the ability of the product to exert
a controlling effect on the biofilm under either static condition or under flow
conditions depending on the use pattern (claim). This controlling effect can be
to destroy and detach, inhibit or prevent the formation of a biofilm
3) a
field trial, where the biofilm is formed under (simulated) use conditions.
These tests should be performed in sequence to obtain more complete
information on the activity of the product on biofilm.
For biofilm disinfection (curative) a suspension test (as for (1) above)
and suitable robust data from either a simulated use test (2) or field trial
(3) should be performed. If there are no robust data from a simulated use test
(2), a field test (3) is mandatory.
For biofilm prevention the approach is different to that for biofilm
disinfection, as the biocide is present before the biofilm is formed and may
affect the early adhesion of cells to the surface or the viability of the
cells. In this case the suspension test (1) may not be useful since the product
might not have a –cidal effect.
3.11.2.1 Test Methodologies
3.11.2.1.1
Suspension tests
The first step in the tiered approach is a suspension test. The CEN
phase 2/step 1 tests are suitable as suspension tests. This test is only
applicable for products that can be tested in suspension and which have a
–cidal effect.
3.11.2.1.2
Simulated use tests
Standard laboratory tests to verify the efficacy of biocides against
biofilms are not currently available. Therefore, before carrying out a biofilm
test, any test methods should be agreed with the Competent Authority.
Applicants should provide a method following the principles in this guidance
and based on scientific evidence. During development of the tests Competent
Authorities of member states should be consulted to make sure that the tests
are acceptable.
Biofilms can be formed and evaluated in static or flow conditions. The
way the biofilm is formed has an effect on the susceptibility of the biofilm to
biocides: biofilms formed under flow conditions are generally more resistant to
biocides than biofilm formed under static conditions.
The conditions under which the biocidal products will have to operate
should also be taken into account. Under static conditions the disinfectant
operates without the aid of the removal effect of a fluid flow or shear stress.
Under flow conditions the contact time might be shorter when shock dosing is used.
Static tests are less expensive and easier to standardise, but flow
tests are generally closer to the real use scenarios.
In both cases, the reproducibility and repeatability of results over
time should be ensured; so a method that allows a series of observations,
rather than a single one, should be employed.
Laboratory for testing the efficacy of biofilm disinfectants should
emulate the critical factors of a real-world environment.
In cases where only efficacy against biofilm formed under static conditions
is claimed (e.g. use in tanks without flow) it is sufficient to only test
against these biofilms.
Examples of methods for testing under flow and static conditions are
described below, but other protocols are available in literature or may be
under development.
3.11.2.2 Static condition assay
Standard laboratory tests to verify the efficacy of biocides against
biofilms formed under static conditions are not currently available. However,
literature describes several methods of how to create a biofilm in the laboratory
under static conditions.
An example of a semi-quantitative method for biofilm evaluation is the
microplate test, where biofilm is formed in static conditions and the amount of
biofilm can be quantified by spectrophotometric measurements. The amount of
living cells in the biofilm before and after treatment can also be determined.
In this case, the disinfectant operates without the aid of the removal effect
of a fluid flow or shear stress.
A positive aspect of such assay is that it is a low cost,
easy-to-conduct test, that allows several replicates and/or testing of several
conditions (several biocide concentrations, more species, etc) to be carried
out, which would provide the basis for a more accurate and closer-to-reality
test.
This method consists of the formation of a biofilm by the species of
interest on the bottom of 96 well plates (the material and coating of the
plates should be specified); the disinfectant may be present before (preventive
effect) or after (inhibition/removal effect) the biofilm is formed. The amount
of biofilm (biomass) is quantified after staining of the adherent material and
spectrophotometric measurement. Detecting agents such as ATP to measure bacterial
viability may also be used.
3.11.2.3 Flow condition assay
Standard laboratory tests to verify the efficacy of biocides against
biofilm formed under flow conditions are not currently available. However,
systems to generate a standard biofilm have been developed by CEN (CEN ISO/TS
15883-5:2005 Annex F) and ASTM (ASTM E2196 and ASTM E2562). Using either of
these reproducible biofilms, a method for the assessment of prevention and/or
elimination of biofilm in terms of viable cells reduction and bacterial biomass
reduction can be carried out.
The CEN method consists of the production of a standard Pseudomonas
aeruginosa biofilm inside a Teflon tube, using a flowing system to simulate
a real world situation.
ASTM E2196 and ASTM E2562 standards use biofilm rotating disc reactors,
which are especially suited for high shear forces.
The biofilm is then treated with a disinfectant to evaluate the biocidal
capacity to remove or to reduce the biofilm.
Other carrier types (e.g. silicon, steel, PVC, etc.) can be selected and
used depending on the biofilm development system, and the experimental
conditions can be adapted to compare the efficacy of different treatments in
preventing biofilm formation.
A reference substance of known activity shall be tested in parallel (e.g.
chlorine dioxide, sodium hypochlorite).
3.11.2.4 Field trials
As for other situations in which biocides are used, only field tests
(phase 3 tests) would be fully representative of the activity of the biocide on
biofilms, but these tests are difficult to standardise, and such tests, if
used, should be complemented by laboratory suspension or simulated use tests,
which have a higher degree of robustness and reproducibility.
A field trail should reproduce the in-use conditions of the worst case
situation of the intended uses.
Prevention and/or elimination of biofilm (in terms of viable cells
reduction and bacterial biomass reduction) should be demonstrated by sampling
before and after disinfection.
A field test can be waived if a suitably robust simulated use test,
which adequately mimics the in-use conditions is provided. A robust test could
for instance be a complex pipe system, in which natural biofilm formation takes
place, either in combination with the addition of standard organisms or not.
3.11.2.5 Test organisms
The choice of micro-organisms for a test is relevant, since the use of
only one organism per test is limitating and may not be fully representative of
the real events leading to micro-organism aggregation (biofilms in settings
where disinfectants are used, are normally multi-microbial, i.e. composed by
several different species). Moreover contaminants from environmental sources
may be embedded in the biofilm matrix which may reduce the disinfectant’s
efficacy.
Bacteria are not the only inhabitants of biofilms, as both fungi and
algae may also inhabit biofilms. Protozoans that consume bacteria may feed on
biofilms. Protozoan oocysts and virus particles can become entrapped in a
biofilm and later detach, returning to the environment.
In a suspension test, the standard organisms per claimed group
(bacteria, fungi, etc.) should be tested.
For a general claim of efficacy against biofilm, as a minimum bacteria
should be tested in laboratory biofilm tests. When action against other groups of
organisms (e.g. fungi, algae) is claimed these should be tested too.
In suspension tests the standard organisms should be tested (see
Appendix 4).
Pseudomonas aeruginosa and Staphylococcus aureus are
acceptable test organisms for the laboratory biofilm tests. Mixtures of test
organisms for producing biofilms are only acceptable as additionally testing,
as it is difficult to standardise these tests.
In simulated use or field trials the biofilm may be formed in vivo
with naturally occurring micro-organisms.
A product will be assessed to be sufficiently effective if the required
laboratory and, where relevant, field tests have been carried out (using the
required test organisms and test conditions), and when the pass criteria for the
tests have been met.
Where pass criteria are available in the standard tests these should be
met.
If the test doesn’t provide these criteria, the general criteria in
Appendix 5 can be taken as guidance for the level of reduction required.
Deviations from the pass criteria are possible, but must be justified in the
application. The Competent Authority will evaluate any justification on a case
by case basis, consulting the other Competent Authorities where appropriate,
and decide whether it is acceptable or not.
Disinfection of soil and other substrates (in playgrounds) with biocides
is not common (and so far not claimed for Annex I of the BPD). This is more
often done for plant protection. Therefore, plant protection guidelines and
EPPO standards on soil treatments should be referred to for test methods. The
use of the test methods should be justified with the application.
A treated article within PT2 is any article
which has been treated with or intentionally incorporates one or more biocidal
products and which claims disinfecting or biostatic properties or function,
when they have a primary biocidal function.
For PT2 this includes for instance
self-disinfecting surfaces, surfaces which prevent biofilm formation,
etc..
There is currently little guidance on data
requirements and acceptance criteria available for treated articles, although
OECD test methods are in development.
Several other uses are mentioned in the description of PT2: waste water
and hospital waste disinfection, algaecides for swimming pools and
indoor/outdoor aquatic area (aquaria / garden ponds). No data requirements and
acceptance criteria for these uses are currently available.
Guidance on the requirements for testing “clean-in-place” products is
not currently included.
The guidance will be updated when methods are available.
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