Draft Interim Guidance for Non-Residual Sanitization of Hard Inanimate
Food Contact Surfaces Using Pre-Saturated Towelettes
April 12, 2001
SUBJECT: Draft Interim Guidance for Non-Residual Sanitization of Hard
Inanimate Food Contact Surfaces Using Pre-Saturated Towelettes
The attached draft, interim guidance has been developed for use by AD
staff to provide guidance to applicants regarding appropriate methodology
that should be utilized when conducting efficacy testing for pre-saturated
towelettes. It is a model protocol, which if followed, is likely to provide
the type of testing required by the Agency.
This document addresses the Agency’s recommendations for evaluating
the non-residual sanitizing efficacy of antimicrobial products (specifically
pre-saturated towelettes) after application to hard, inanimate surfaces
with which food may come in contact.
Specifically, the guidance provides details on the following: 1) purpose
and scope of the guidance document, 2) test substance, 3) test methods,
4) reporting of data, 5) test standard, (which includes discussion of
the test organisms, procedure, organic soil load, single pack towelettes
versus roll of towelettes, towelette size and treatment surface area,
and data generation), and 6) performance standard.
This draft, interim guidance should be followed when evaluating efficacy
protocols for products of this type. This document may be released to
the public when requested. If you have any questions, please contact your
branch chief, team leader, or Laura Morris-Bailey.
Attachment
EPA/AD/Method Guidance #02 April 12, 2001
Draft Interim Guidance for AD Staff
Non-Residual Sanitization of Hard Inanimate Food Contact Surfaces Using
Pre-Saturated Towelettes
1. Purpose and Scope
The purpose of this document is to provide interim guidance for the
evaluation of the sanitizing efficacy of antimicrobial products, specifically
pre-saturated towelettes, after application to hard inanimate, nonporous
surfaces. This approach may be used to substantiate bacterial sanitizing
claims for pre-saturated towelettes applied on hard inanimate surfaces
in food contact areas (such as counter tops in restaurants, kitchen cabinets,
etc.). This guidance is limited to single use towelettes in both commercial
and residential environments. Note: This guidance does not address products
for use on utensils, glasses, food containers, dishes, and food processing
equipment.
2. Test Substance
Unless otherwise specified, antimicrobial pesticides are to be tested
with the formulation to be offered for sale using the product packaged
in the same packaging intended to be marketed. Towelettes are a unique
combination of antimicrobial chemical products pre-packaged as a unit
in fixed proportions for application. Therefore, the complete products,
as packaged in the manner to be offered for sale, must be tested according
to the directions for use to insure efficacy as a hard surface sanitizer.
The product tested must be from three batches as referenced in Section
5.6. Simulated re-use is not required since the product is intended to
be removed from the package, used immediately, and discarded after use.
3. Test Methods
Test antimicrobial products in accordance with the proposed directions
for use. Depending upon the type of antimicrobial agent, target microorganisms,
and the site to be treated, all tests are to address those factors that
would normally be expected to be encountered in the use pattern intended
for the product, including, but not limited to, the method of application;
the nature of the surface (i.e., hard non-porous surface), item surface
to be treated; the presence or absence of soil or other interfering conditions;
ambient temperature and exposure period of 30 seconds.
Modification of the standard AOAC Germicidal Spray Products Test, official
final method, (Official Methods of Analysis of the AOAC International.
Chapter 6, Disinfectants, Official Method 961.02 Germicidal Spray Products
as Disinfectants, Seventeenth edition. AOAC International, Suite 500,
481 North Frederick Avenue, Gaithersburg, MD 20877-2417) is appropriate
for this scenario. Instead of spraying the inoculated surface of the glass
slide (as noted in the AOAC Germicidal Spray Products Test method), the
towelette product is tested by wiping the surface of the glass slide with
the saturated towelette, and then subculturing the slides after a 30 second
exposure time. Liquid expressed from the used towelette needs to be subcultured
separately. Subcultures of the liquid expressed from the used towelettes
are expected to be negative for growth.
4. Reporting of Data
Systematic and complete descriptions of the tests employed and (see
item #3 above) the results obtained are essential for proper review and
evaluation of product performance by the Agency. All test reports must
include identification of the testing laboratory or organization, when
and where the tests were conducted and the name of the person(s) responsible
for conducting the tests and those who prepared the study report.
5. Test Standard
The following parameters need to be taken into account when developing
efficacy data for sanitizing activity of towelettes used on hard inanimate
surfaces:
5.1 Test Organisms
Testing is to be based upon an adequately controlled in-use study or
simulated in-use study. At a minimum, the microorganisms that must be
tested are Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC
11229). Testing also must be undertaken for any additional microorganisms
that are claimed on the label. The starting inocula of the test microorganisms
must be of sufficient concentration to provide between 75 - 125 x 106
cfu/ml on the parallel control surface.
5.2 Procedure
Based on the claims, a variety of surfaces may be treated with the product.
Each of the different types of test surfaces claimed may be used in the
efficacy testing of the product (i.e., glass, stainless steel, plastic,
and ceramic). At a minimum, the applicant must test:1) a stainless steel
or glass surface, and 2) a plastic with a rough surface (i.e., plastic
cutting boards). Inoculate the test surface with the challenge microorganisms.
After inoculation, the test surface is dried for 40 minutes in an incubator
at 30 - 37EC. A "zero-time" bacterial numbers recovery test
must be performed to demonstrate the efficiency of the recovery process,
and must be reported.
The towelette is removed from its container and handled with sterile
gloves. The inoculated surfaces are to be tested by wiping the surfaces
with the saturated towelette. The area of the towelette used for wiping
is rotated so as to expose a maximum amount of its surface in the course
of wiping the contaminated test surface. After wiping the contaminated
surface with the towelette, all remaining liquid is to be expressed from
the used towelette into an empty sterile container and subcultured separately.
Run parallel tests on the towelette (as well as expressed liquid from
the used towelette) with the active ingredients omitted in an identical
manner to serve as the control.
After the 30 second contact time, recover the test microorganisms by
washing the treated surfaces with adequate agitation in an appropriate
media or dilution fluid containing appropriate neutralizers. Enumerate
microorganisms on appropriate nutrient agar, containing the same neutralizers,
by the pour or spread plate technique.
The environmental conditions, such as relative humidity and temperature,
employed in the test must also be reported. These conditions must be the
same as those likely to be encountered under normal conditions of use.
5.3 Organic Soil Load
For products making one-step sanitization claims, the test surface must
have an organic soil load applied to the surface prior to the initial
treatment and challenge (at a minimum 5% bovine serum). The organic soil
level indicated is considered appropriate for simulating lightly or moderately
soiled surface conditions. When the surface to be treated has heavy soil
deposits, a cleaning step must be required on the label prior to the application
of the antimicrobial agent. In the absence of testing with an organic
soil load, a one-step claim cannot be made and a pre-cleaning step is
required and must be noted on the label.
5.4 Single Pack Towelettes Versus Roll of Towelettes
There may be more moisture retained in a towelette from single pack
towelettes than in a towelette from a roll of towelettes. If the towelette
roll container does not remain closed, there is a possibility that the
towelettes at the end of the roll may not contain as much moisture as
those towelettes at the start of the roll. Therefore, to ensure continued
efficacy, the label needs to state that the towelette must be visibly
wet (saturated) before use, and that the surface treated must be visibly
wet after use.
5.5 Towelette Size and Surface Area
At this time, there are no limitations/restrictions regarding the size
of the towelette. The Agency’s suggested minimum surface area to
be treated per towelette is 2' x 2'. However, the size of the surface
area treated must be representative of the area that the towelette will
treat effectively and reflective of the surface area to be tested in the
study. The size of the surface area to be treated, as demonstrated by
the data, must also be stated on the label as the recommended maximum
surface area to be treated.
5.6 Data Generation
Three samples, representing three different batches, one of which is
at least 60 days old, must be evaluated for efficacy against Escherichia
coli (ATCC 11229) and Staphylococcus aureus (ATCC 6538). Testing for additional
microorganisms claimed on the label is to be conducted on two batches
of product. Tests are to be conducted in triplicate.
6. Performance standard
The product must demonstrate at least a 99.999% reduction in the number
of test microorganisms (bacteria) within 30 seconds. The result must be
reported according to the actual count and percentage reduction over the
control.
Guidance approved as Agency standard April 12, 2001 by the Office of
Pesticide Programs/Antimicrobials Division.
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