ASTM F1608-00(2004)
(Test Method)Standard Test Method for Microbial Ranking of Porous Packaging Materials (Exposure Chamber Method)
Standard Test Method for Microbial Ranking of Porous Packaging Materials (Exposure Chamber Method)
SIGNIFICANCE AND USE
The exposure-chamber method is a quantitative procedure for determining the microbial-barrier properties of porous materials under the conditions specified by the test. Data obtained from this test are useful in assessing the relative potential of a particular porous material to contribute to the loss of sterility to the contents of the package versus another porous material. This test method is not intended to predict the performance of a given material in a specific sterile-packaging application. The maintenance of sterility in a particular packaging application will depend on a number of factors, including, but not limited to the following:
5.1.1 The bacterial challenge (number and kinds of microorganisms) that the package will encounter in its distribution and use. This may be influenced by factors such as shipping methods, expected shelf life, geographic location, and storage conditions.
5.1.2 The package design, including factors such as adhesion between materials, the presence or absence of secondary and tertiary packaging, and the nature of the device within the package.
5.1.3 The rate and volume exchange of air that the porous package encounters during its distribution and shelf life. This can be influenced by factors including the free-air volume within the package and pressure changes occurring as a result of transportation, manipulation, weather, or mechanical influences (such as room door closures and HVAC systems).
5.1.4 The microstructure of a porous material which influences the relative ability to adsorb or entrap microorganisms, or both, under different air-flow conditions.
SCOPE
1.1 This test method is used to determine the passage of airborne bacteria through porous materials intended for use in packaging sterile medical devices. This test method is designed to test materials under conditions that result in the detectable passage of bacterial spores through the test material.
1.1.1 A round-robin study was conducted with eleven laboratories participating. Each laboratory tested duplicate samples of six commercially available porous materials to determine the LRV. Materials tested under the standard conditions described in this test method returned average values that range from LRV 1.7 to 4.3.
1.1.2 Results of this round-robin study indicate that caution should be used when comparing test data and ranking materials, especially when a small number of sample replicates are used. In addition, further collaborative work (such as described in Practice E691) should be conducted before this test method would be condsidered adequate for purposes of setting performance standards.
1.2 This test method requires manipulation of microorganisms and should be performed only by trained personnel. The U.S. Department of Health and Human Services publication Biosafety in Microbiological and Biomedical Laboratories (CDC/NIH-HHS Publication No. 84-8395) should be consulted for guidance.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:F1608–00 (Reapproved 2004)
Standard Test Method for
Microbial Ranking of Porous Packaging Materials (Exposure
Chamber Method)
This standard is issued under the fixed designation F1608; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1.1 This test method is used to determine the passage of
E691 Practice for Conducting an Interlaboratory Study to
airborne bacteria through porous materials intended for use in
Determine the Precision of a Test Method
packagingsterilemedicaldevices.Thistestmethodisdesigned
to test materials under conditions that result in the detectable
3. Terminology
passage of bacterial spores through the test material.
3.1 Definition:
1.1.1 Around-robin study was conducted with eleven labo-
3.1.1 porous packaging material, n—a material used in
ratories participating. Each laboratory tested duplicate samples
medical packaging which is intended to provide an environ-
of six commercially available porous materials to determine
mentalandbiologicalbarrier,whileallowingsufficientairflow
the LRV. Materials tested under the standard conditions de-
to be used in gaseous sterilization methods (for example, EO,
scribed in this test method returned average values that range
steam, gas plasma).
from LRV 1.7 to 4.3.
1.1.2 Results of this round-robin study indicate that caution
4. Summary of Test Method
should be used when comparing test data and ranking materi-
4.1 Samples of porous materials are subjected to an aerosol
als, especially when a small number of sample replicates are
of Bacillus subtilis var. niger spores within an exposure
used.Inaddition,furthercollaborativework(suchasdescribed
chamber. Spores which pass through the porous sample are
in Practice E691) should be conducted before this test method
collected on membrane filters and enumerated. The logarithm
would be condsidered adequate for purposes of setting perfor-
reduction value (LRV) is calculated by comparing the loga-
mance standards.
rithm of the number of spores passing through the porous
1.2 This test method requires manipulation of microorgan-
material with the logarithm of the microbial challenge.
isms and should be performed only by trained personnel. The
4.2 Standard Set of Conditions—This test method specifies
U.S. Department of Health and Human Services publication
a standard set of conditions for conducting the exposure
Biosafety in Microbiological and Biomedical Laboratories
chambertestmethod.Astandardsetofconditionsisrequiredto
(CDC/NIH-HHS Publication No. 84-8395) should be con-
enable evaluation of materials between laboratories. The con-
sulted for guidance.
ditions stated in this test method were chosen for several
1.3 This standard does not purport to address all of the
reasons. First, it is difficult to maintain an aerosol of spores
safety concerns, if any, associated with its use. It is the
over long periods of time. (Also, if the spore challenge time is
responsibility of the user of this standard to establish appro-
long, the cost of the test increases). Second, to determine the
priate safety and health practices and determine the applica-
differences between materials, it is necessary to test the
bility of regulatory limitations prior to use.
materials under conditions which allow passage of bacterial
2. Referenced Documents spores. If a material does not allow any passage of spores, all
2 that can be stated is that it has better resistance to penetration
2.1 ASTM Standards:
than the severity of the challenge conditions. Third, it is
necessary to have a large spore challenge level to be able to
ThistestmethodisunderthejurisdictionofASTMCommitteeF02onFlexible
detect the passage of spores through the entire range of
Barrier Materials and is the direct responsibility of Subcommittee F02.15 on
commercially available porous packaging materials. The stan-
Chemical/Safety Properties.
dard conditions stated in this test method are based upon these
Current edition approved Oct. 1, 2004. Published October 2004. Originally
approved in 1995. Last previous edition approved in 2000 as F1608–00. DOI: factors. (Additional information may be found in the Refer-
10.1520/F1608-00R04.
ences section). However, since many factors influence the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
determination of an appropriate porous material (outlined in
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.1.1-5.1.4), each user may modify these conditions (that is,
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1608–00 (2004)
bacterial challenge, time, flow rate) after first conducting within the package and pressure changes occurring as a result
studiesatthespecifiedstandardconditions.Thestandardsetof of transportation, manipulation, weather, or mechanical influ-
targetparametersforconductingthetestmethodareasfollows:
ences (such as room door closures and HVAC systems).
4.2.1 Flow Rate Through Sample—2.8 L/min.
5.1.4 The microstructure of a porous material which influ-
4.2.2 Exposure Time— 15 min.
ences the relative ability to adsorb or entrap microorganisms,
4.2.3 Target Microbial Challenge—1 310 colonyforming
or both, under different air-flow conditions.
units (CFU)/sample port.
6. Apparatus
5. Significance and Use
6.1 This procedure should be conducted in a microbiologi-
5.1 The exposure-chamber method is a quantitative proce-
cal laboratory by trained personnel. As a result, it is assumed
dure for determining the microbial-barrier properties of porous
thatbasicmicrobiologicalequipmentandsuppliesforconduct-
materials under the conditions specified by the test. Data
ing routine microbiological manipulations (that is, standard
obtained from this test are useful in assessing the relative
plate counts, sterilization with an autoclave, and so forth) will
potentialofaparticularporousmaterialtocontributetotheloss
be available.
ofsterilitytothecontentsofthepackageversusanotherporous
material. This test method is not intended to predict the
6.2 Exposure Chamber, constructed primarily from acrylic
performance of a given material in a specific sterile-packaging
sheeting and consists of two major sections, as illustrated in
application. The maintenance of sterility in a particular pack-
Fig. 1. The bottom section contains a six-place manifold
aging application will depend on a number of factors, includ-
connected to six flowmeters, one per port, containing hoses
ing, but not limited to the following:
attached to six filtering units. The port to the manifold is
5.1.1 The bacterial challenge (number and kinds of micro-
attached to a vacuum source. A vacuum gage is mounted
organisms) that the package will encounter in its distribution
between the manifold and the vacuum source. The upper
and use. This may be influenced by factors such as shipping
chamber contains a fan for dispersion of the bacterial aerosol,
methods, expected shelf life, geographic location, and storage
aportforattachmentofthenebulizer,aportforexhaustingthe
conditions.
chamber, and a plate for attachment of disposable or steriliz-
5.1.2 The package design, including factors such as adhe-
ablefilterunits.Thechambermayusedisposablefilterunitsor
sion between materials, the presence or absence of secondary
reusable filter units, or both.
and tertiary packaging, and the nature of the device within the
package.
7. Materials
5.1.3 The rate and volume exchange of air that the porous
package encounters during its distribution and shelf life. This 7.1 Bacillus subtilis var. niger (ATCC9372), aqueous spore
can be influenced by factors including the free-air volume suspension in water.
FIG. 1 Exposure Chamber
F1608–00 (2004)
7.2 Soybean Casein Digest Agar—Bottles for pour plates 9.1.2 Connect the top of each of the six flowmeters to the
and pre-poured plates (;25 mL in 100 by 15-mm plates) manifold using 0.65-cm inside diameter hoses. Connect the
prepared commercially or in accordance with standard tech- manifold to a filtered vacuum source.
niques. 9.1.3 Connect the bottom of each sample flowmeter to a
filter unit with 0.65-cm inside diameter hose using an end
7.3 Sterile Cellulose Nitrate Filters, 47 or 50-mm diameter,
depending upon filter unit specification, 0.45-µm pore size. connector.
9.1.4 Using a rubber hose, attach the nebulizer to a tee
7.4 Sterile Bottle-Top Filter Units, (Falcon-type 7104 or
connector made of a 0.65-cm PVC and three pieces of 0.6-cm
filter holders with funnel 310-4000 or equivalent).
inside diameter PVC piping approximately 7.5 cm long.
7.5 Glass Nebulizer.
9.1.5 Attach the vertical leg of the tee to a trap jar using a
7.6 Sterile Forceps.
rubber stopper with a 0.65-cm diameter hole. The trap jar is
7.7 Incubator, 30 to 35°C.
intended to retain any unsuspended droplets produced by the
7.8 Disk Cutter, 47 or 50-mm diameter, depending upon
nebulizer.
filter unit specification.
9.1.6 Attach the second end of the tee to a 1.3-cm inside
7.9 Sterile Gloves.
3 diameterrubbertubingapproximately3.8cmlongandconnect
7.10 Sterile Syringe, 3-cm with needle or micropipette.
to the front port of the chamber.
7.11 Sterile Pipettes, to deliver 0.1, 1, 10, and 25 mL.
9.1.7 Attach a 1.3-cm inside diameter rubber tubing ap-
7.12 Blender, with sterile ⁄2-pt jar(s).
proximately16cmlongtothemouthofthenebulizer.Connect
7.13 Vortex Mixer.
the loose end of the tubing to the third end of the tee.
7.14 Vacuum Pump, with air filter.
9.1.8 Connect the nebulizer inlet port with a 0.5-cm inside
7.15 Calibrated Timer.
diameterrubbertubingtothetopportofacalibratedflowmeter
7.16 Calibrated Flowmeters—Oneeachwitharangefrom5
(from 5 to 30-L/min range).
to 30 L/min; six each with a range from 1.0 to 5.0 L/min.
9.1.9 Connect the bottom port of the nebulizer to a filtered
7.17 Sterile Petri Plates.
air source.
7.18 Sterile Water, 100 and 9.9-mL aliquots, or other
9.1.10 Attach the exhaust port of the chamber that is used
appropriate volumes for membrane grinding and dilutions.
for evacuation to a 1.3-cm inside diameter tubing which, in
7.19 Hoses and Piping— See Section 9 for lengths and
turn, leads to an air filter and to a vacuum source.
diameters.
9.2 Filter Unit-Holder Preparation:
7.20 Rubber Stoppers with Holes—See Section 9 for sizes.
9.2.1 Wrap each non-sterile sterilizable filter unit in a
7.21 Trap Jar.
sterilizable wrap.
7.22 Calibrated Vacuum Gage.
9.2.2 Sterilize the filter units as specified by the manufac-
7.23 Compressed Air Source, with air filter.
turer. Presterilized filter units do not need to be resterilized.
7.24 Biocontainment Hood.
10. Apparatus Validation
7.25 Chlorine Bleach, or suitable sporocide.
10.1 The test apparatus (see Fig. 1) must be validated for
bacterialchallengetoeachport.Thisstepshouldbeperformed
8. Sample Preparation
upon first use of the chamber and a minimum of three runs
8.1 Cutrandomsamplesofmaterialintodisksinaccordance
should be conducted. The following description outlines vali-
with the size required for the filter holder being used (47 or 50
dation of the test procedure for a challenge of 1 310 colony
mm) using a disk cutter. It is suggested that additional samples
forming units (CFU) per port in 15 min at a flow rate of 2.8
be cut to allow for errors during the procedure. Typically, the
L/min. If testing is to be conducted using other parameters, a
sample disks are sterilized prior to testing using a test method
validation should be conducted using those parameters.
appropriate for the specific material. Materials may also be
10.1.1 Aseptically place a sterile 0.45-µm membrane filter
tested before or after they are subjected to other conditions
on the base of each filter unit using sterile forceps and gloves
such as heat or cold, relative humidity, different sterilization
(Fig. 2).
processes, real time, or accelerated aging.The samples may be
10.1.2 Attach the top of the filter unit to the bottom of the
stored in sterile petri plates or other suitable sterile containers
exposure chamber.Then attach each filter unit to its respective
before testing.
flowmeter.
8.2 The minimum sample size for a given material is two,
10.1.3 Dispense 3.0 mL of the desired aqueous spore
which was used in the round-robin study of this test method.
suspension into the nebulizer. When using the DeVilbiss #40
However,itisstronglysuggestedthatmoresamplesbeusedto 7
nebulizer, a volume of 3.0 mL at a concentration of 5 310
improve precision and bias (Section 14).
spores/mLis necessary to achieve a challenge of 1 310 CFU
(60.5 log) per port in 15 min.
9. Apparatus Preparation
10.1.4 Turn on the chamber fan.
9.1 Since aerosols containing bacterial spores are formed 10.1.5 Adjust port flowmeters to 2.8 L/min. It is important
duringtheuseofthisapparatus,theexposurechamber(seeFig.
that all ports be set to the same flow and monitored during the
1) should be assembled and used within a biological safety exposure period. Before adjusting each flowmeter, open each
cabinet.
valve completely, then slowly open the vacuum and fine adjust
9.1.1 Place the top of the chamber on the bottom base. until the desired flow is achieved.
F1608–00 (2004)
FIG. 3 Dilution Scheme
round-robin study, includes plating 10.0, 1.0, and 0.1-mL
aliquotsoftheblendedmembraneinduplicate.Anadditional1
FIG. 2 Sample and Control Material Setup
to 100 dilution is prepared by placing 0.1 mL in 9.9 mL of
sterile water and plating 1.0 and 0.1-mL aliquots of this
dilution in duplicate. This scheme produces dilution factors of
10.1.6 Adjust the nebulizer flow rate as recommended by
−1 −2 −3 −4 −5
10 ,10 ,10 ,10 , and 10 . Other dilution protocols may
the nebulizer manufacturer to produce droplets that are within
be used. Plates having between 25 and 250 CFU should be
the appropriate particle size range. When using the DeVilbiss
used for enumeration. If alternative test conditions are used,
#40 nebulizer, a flow rate of 8.5 L/min is used.
then the previously described dilution scheme may not be
10.1.7 Immediately start the 15-min timer.At regular inter-
appropriate. In instances where colony counts are less than 30
vals, observe and adjust (if necessary) all flowmeters to
CFU, the limit of detection is dependent upon the volume of
maintain the appropriate flow rate settings during the 15-mi
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.