&EPA
United States
Environmental Protection
Agency
REPORT ON
Destruction of Spores on Building
Decontamination Residue in a
Commercial Autoclave
National Homeland Security Research Center
Office of Research and Development
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EPA/600/R-05/081
April 2005
Destruction of Spores on
Building Decontamination Residue
in a Commercial Autoclave
by:
Roy Sieber and Aaron Osborne
Eastern Research Group, Inc.
14555 Avion Parkway, Suite 200
Chantilly, VA20151
Dr. Paul Lemieux
U.S. Environmental Protection Agency
Office of Research and Development
National Homeland Security Research Center
Research Triangle Park, NC 27711
EP-C-04-056
Project Officer
Alice Gagnon
U.S. Environmental Protection Agency
Office of Research and Development
National Risk Management Research Laboratory
Research Triangle Park, NC 27711
U.S. Environmental Protection Agency
Office of Research and Development
National Homeland Security Research Center
Decontamination and Consequence Management Division
Research Triangle Park, NC 27711
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NOTICE
The U.S. Environmental Protection Agency (EPA), through its Office of Research
and Development, funded this study under Contract Number EP-C-04-056, Work Assignment 0-
7 to Eastern Research Group, Inc. (ERG). This report presents the methodology followed and the
results of this study to evaluate the effectiveness of a commercial autoclave sterilizing simulated
building decontamination residue. Simulated building decontamination residue consisting of
wallboard, ceiling tiles, carpet, and upholstered furniture was prepared with 106 population
biological indicator test strips of Geobacillus stearothermophilus. The residue was then
autoclaved under different conditions to evaluate the influence of the following variables on
sterilization: time, temperature, pressure, item type, moisture content, packing density, packing
orientation, autoclave bag integrity, and autoclave process sequence. While the results of this
study provide valuable data on autoclave performance, this report is not EPA guidance and
should not be viewed as such.
Mention of trade names, products, or services does not convey, and should not be
interpreted as conveying, official EPA approval, endorsement, or recommendation.
This report has been subjected to the Agency's peer and administrative review
and has been approved for publication as an EPA document.
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FOREWARD
The U.S. EPA National Homeland Security Research Center (NHSRC),
Decontamination and Consequence Management Division (DCMD), one of three divisions of
NHSRC, is located in Research Triangle Park, North Carolina. The current focus of DCMD is on
the decontamination of buildings that have been intentionally contaminated with biological or
chemical agents. DCMD scientists study the biological or chemical contamination of air and
indoor surfaces; provide methods for upgrading buildings in ways that increase occupant
protection; supply information on decontamination methods, including safety, efficiency, cost;
and analyze disposal options for decontamination wastes.
This study was conducted as part of the DCMD research goal of evaluating
commercial decontamination methods and systems. This report is being published to disseminate
the findings of this study to the potential user community and other interested parties.
11
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ACKNOWLEDGMENTS
This study was led by Dr. Paul Lemieux, U.S. EPA, Office of Research and
Development, National Homeland Security Research Center, Decontamination and Consequence
Management Division. ERG prepared simulated building decontamination residue and conducted
the autoclave testing. The ERG test team included Roy Sieber, Aaron Osborne, Scott Sholar,
and Steve Strackbein. Dave Dayton of ERG designed and built the temperature acquisition
system described herein. Dr. Alan Woodard, New York State Department of Environmental
Conservation, provided invaluable technical input during the planning and conduct of this study.
The autoclave test would not have been possible without the facility access, cooperation, and
technical expertise provided by Healthcare Environmental, Inc. Thank you to Richard Geisser,
Vice President, Russ Hilton, Plant Manager, and all the dedicated members of the Healthcare
Environmental team.
in
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ABSTRACT
In the event of a terrorist attack on a building where biological weapons such as anthrax
might be used, much of the porous material in the building will be shipped for disposal after
decontamination activities. This material is collectively termed "building decontamination
residue" (BDR). Although the BDR will have been disinfected or decontaminated, it is possible
that residual biological agent will remain in the material.
Autoclaves are commonly used to sterilize regulated medical waste by exposing the
waste to elevated pressures and temperatures for extended periods of time (e.g., 31.5 psig, 275°F,
and 40 minutes). However, some types of BDR may be densely packed or have low thermal
conductivity and may require longer periods of time to reach the operating temperature of an
autoclave. This report addresses whether the standard operating procedure in a commercial
autoclave will provide sufficient time/temperature/pressure to adequately destroy bacteria spores
bound on BDR.
This study investigated the effect of several variables related to autoclaving BDR,
including time, temperature, pressure, item type, moisture content, packing density, packing
orientation, autoclave bag integrity, and autoclave process sequence. The test team created
simulated BDR from wallboard, ceiling tiles, carpet, and upholstered furniture, embedded with
106 population Geobacillus stearothermophilus biological indicator (BI) strips and
thermocouples to obtain time/temperature profile data associated with each BI strip.
Study results indicate that bags of BDR should be placed in an autoclave so that
all sides of individual bags are exposed to autoclave conditions, and not nested or stacked in a
manner that precludes full exposure. All materials tested were effectively sterilized when dry.
Increasing moisture content made autoclaving more difficult, but wet wallboard and ceiling tiles
were also effectively sterilized. Autoclave cycles of 120 minutes at 31.5 psig/ 275°F and 75
minutes at 45 psig/ 292°F effectively sterilized the BDR material. Two standard autoclave cycles
of 40 minutes and 31.5 psig/ 275°F run in sequence proved to be particularly effective, probably
because the second cycle's evacuation step pulled the condensed water out of the pores of the
materials, allowing effective steam penetration.
iv
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TABLE OF CONTENTS
Page
1.0 INTRODUCTION 1-1
2.0 EXPERIMENTAL APPROACH 2-1
2.1 Autoclave Description 2-1
2.2 Testing Approach 2-1
2.3 Test Matrix and Conditions 2-2
2.3.1 Item Type 2-3
2.3.1.1 Wallboard 2-6
2.3.1.2 Ceiling Tiles 2-7
2.3.1.3 Carpet 2-8
2.3.1.4 Sofa 2-10
2.3.2 Autoclave Packing Density 2-10
2.3.3 Moisture Content 2-11
2.3.4 Temperature and Pressure 2-11
2.3.5 Time 2-12
2.3.6 Packing Orientation 2-12
2.3.7 Open Bags 2-13
2.3.8 Multiple Short Cycles 2-13
2.4 Test Schedule 2-13
3.0 RESULTS 3-1
3.1 Time/Temperature Data 3-1
3.2 Biological Indicator Data 3-1
3.3 Quality Assurance Data 3-2
3.3.1 Process Measurements 3-2
3.3.2 Experimental Measurements 3-2
3.3.2.1 RunTime 3-2
3.3.2.2 Temperature 3-10
3.3.2.3 Test Conditions 3-11
3.3.2.4 BI Test Strip Results 3-11
4.0 DISCUSSION 4-1
4.1 Time and Temperature Effect on Sterilization 4-1
4.2 Item Type and Moisture Content 4-2
4.3 Autoclave Packing Density and Location 4-3
4.4 Temperature and Pressure 4-5
4.5 Packing Orientation 4-5
4.6 Open Bags 4-6
4.7 Two Sequential Cycles 4-6
5.0 CONCLUSIONS 5-1
6.0 REFERENCES 6-1
Appendix A PHOTOGRAPHIC LOG
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LIST OF TABLES
Page
Table 2-1. Originally Planned Healthcare Environmental Autoclave Test Matrix 2-4
Table 2-2. Healthcare Environmental Autoclave Test Matrix as Completed 2-5
Table 3-1. Biological Indicator Data 3-3
VI
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LIST OF FIGURES
Page
Figure 2-1. Side View Sketch of Dense Packing Arrangement 2-7
Figure 2-2. Configuration of Sample Points in a Large Carpet Roll 2-10
Figure 3-1. Run 1 Time/Temperature Data 3-13
Figure 3-3. Run 4 Time/Temperature Data 3-15
Figure 3-4. Run 8 Time/Temperature Data 3-16
Figure 3-5. Run 5 Time/Temperature Data 3-17
Figure 3-6. Run 6 Time/Temperature Data 3-18
Figure 4-1. Run 2 Spore Viability 4-8
Figure 4-2. Run 4 Spore Viability 4-9
Figure 4-3. Run 5 Spore Viability 4-10
Figure 4-4. Run 1 Moisture Content and Item Type Comparison 4-11
Figure 4-5. Run 8 Moisture Content and Item Type Comparison 4-12
Figure 4-6. Run 5 Moisture Content and Item Type Comparison (Uncut Bags Only) 4-13
Figure 4-7. Run 6 Moisture Content and Item Type Comparison 4-14
Figure 4-8. Wallboard Packing Density Comparison 4-15
Figure 4-9. Carpet Packing Density Comparison 4-16
Figure 4-10. Run 2 Dense Packing Layer Comparison 4-17
Figure 4-11. Comparison of Sampling Points within Selected Wallboard Bags 4-18
Figure 4-12. Comparison of Sampling Points within Selected Ceiling Tile Bags 4-19
Figure 4-13. Autoclave Temperature Comparison for Wallboard 4-20
Figure 4-14. Autoclave Temperature Comparison for Ceiling Tiles 4-21
Figure 4-15. Horizontal Versus Vertical Packing Orientation for Wallboard 4-22
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Figure 4-16. Horizontal Versus Vertical Packing Orientation for Ceiling Tiles 4-23
Figure 4-17. Horizontal Versus Vertical Packing Orientation for Carpet 4-24
Figure 4-18. Cut Versus Uncut Wallboard Bags 4-25
Figure 4-19. Cut Versus Uncut Ceiling Tile Bags 4-26
Figure 4-20. Cut Versus Uncut Carpet Bags 4-27
Vlll
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i.o INTRODUCTION
In the event of a terrorist attack on a building where biological weapons (BW)
such as anthrax might be used, much of the porous material in the building will be shipped for
disposal after decontamination activities. These materials are collectively termed "building
decontamination residue" (BDR). Although the BDR will have been disinfected or
decontaminated, it is possible that residual BW agent will remain in the material. Many of these
materials might be tightly packed and possibly wet. Autoclaves are commonly used to
effectively treat regulated medical waste by exposing the waste to elevated pressures and
temperatures for extended periods of time (e.g., 31.5 psig, 275°F, and 40 minutes at the test
facility). However, BDR has low thermal conductivity and may require more time to reach the
operating temperature of an autoclave.
It is unknown whether the standard operating procedure in a commercial
autoclave will provide sufficient time/temperature/pressure to adequately destroy bacteria spores
bound on BDR. The primary objective of this study was to determine what recommended
operating conditions at a commercial medical waste autoclave are sufficient to destroy bacteria
spores found on BDR. The secondary objective of this study was to investigate the
time/temperature dependence of Geobacillus stearothermophilus spore destruction as a function
of autoclove operating conditions and BDR composition. The commercial autoclave tested is
operated by Healthcare Environmental, Inc., in Oneonta, NY. Viability of bacteria spores was
tested using 106 population biological indicator (BI) strips of viable spores of Geobacillus
stearothermophilus, embedded in the materials processed by the autoclave. BDR materials
tested included carpeting, wallboard, and ceiling tiles, both dry and wetted with water.
Additionally, a sofa was processed to test the efficacy of autoclaving upholstered furniture.
This study was performed according to an approved Quality Assurance Project
Pla (QAPP), Destruction of Spores on Building Decontamination Residue in a Commercial
Autoclave (1).
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2.0 EXPERIMENTAL APPROACH
2.1 Autoclave Description
This test was conducted at the Healthcare Environmental, Inc. facility located in
Oneonta, Oswego County, approximately 90 miles from Albany, New York. The facility
operates a permitted, regulated medical waste autoclave process with approximately 84 tons/day
(TPD) capacity. The facility has two large autoclaves 8 feet in diameter and 32 feet long, which
accept large bins (80 inches by 54 inches by 69 inches) on rollers. Each autoclave can process 6
bins, with a total mass of approximately 3,000-4,000 pounds per cycle. Photographs 17 through
20 show the autoclave configuration. All photographs of the test are provided in Appendix A to
this report.
The nominal autoclave operating cycle time is 40 minutes plus cool-down time to
prepare for subsequent charges. At the start of each cycle, the autoclave is sealed and air is
evacuated for 3 minutes using a vacuum pump to approximately -10 psig. Steam is then injected
to reach and maintain the desired operating pressure and temperature, which are typically
achieved in approximately 5 minutes. The nominal operating conditions during the cycles are
31.5 psig and 275°F. Steam is injected through three ports at the top of the autoclave, located at
the front, center and rear. The steam is injected over distributor plates to cause turbulent,
disbursed steam flow throughout the autoclave. At the end of each cycle, steam is evacuated by
again pulling vacuum. Both autoclave units are identical. The facility continuously measures
the operating temperature and pressure within each autoclave unit using a digital readout and
paper chart recorder.
2.2 Testing Approach
Autoclave performance was judged based on two parameters: real-time
measurements from thermocouples embedded in each simulated load of BDR material tested and
viability of 106 Geobacillus stearothermophilus BI test strips embedded within each load tested.
The testing comprised a series of test runs at different conditions on one of the facility autoclaves
(Unit Al). Section 2.3 discusses the conditions tested.
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For each test run, the BDR material processed was wired with 24 thermocouples
to record the time/temperature profile at different locations embedded within the load. A BI
pouch was paired with a thermocouple at each test location. Each BI pouch contained two
Geobacillus stearothermophilus indicator strips, labeled 'A' and 'B'. After the test, the A strips
were analyzed for a growth/no-growth indication, and a population assay was performed on the
B strips if the A strips grew, as discussed in Section 3.2. Additionally, control thermocouples
not embedded in BDR recorded the temperature inside and outside the autoclave. Three types of
control BI test pouches, further explained in Section 3.3.2.4, were also collected: BI test pouches
fully exposed to the autoclave conditions, BI test pouches packaged and handled similarly to
other BDR but not autoclaved, and duplicate BI test pouches.
2.3 Test Matrix and Conditions
As discussed in the QAPP, the following variables were identified as having a
potential impact on sterilization capability:
1. Item type;
2. Autoclave packing density (i.e., loose packing versus dense packing);
3. Moisture content of autoclaved materials;
4. Autoclave temperature/pressure; and
5. Time in autoclave.
The test matrix presented in Table 2-1 was designed to investigate the effects of
each of these variables.
Temperature data from initial test runs indicated that internal temperatures of
densely packed material responded slowly to autoclave conditions, and therefore, this material
was not likely being sterilized after 120 minutes, the maximum autoclave run time established
for the test. After discussion among the EPA Work Assignment Manager (WAM), ERG WAM,
New York State Department of Environmental Conservation (NYSDEC) representative, and the
autoclave facility manager, originally planned Runs 2, 5, 6, and 7 were deleted and three
2-2
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additional factors were identified and tested to determine if they improved sterilization
capability:
1. Positioning sample bags of BDR vertically instead of horizontally;
2. Cutting open the bags of BDR to facilitate steam penetration; and
3. Running two shorter process cycles in sequence instead of one long cycle.
A revised test matrix was developed based on the temperature results of the initial
runs and the objective of testing additional factors to improve sterilization. The changes to the
test matrix were based partially on altering test conditions within easily adjusted facility
operating constraints. Table 2-2 presents the revised test matrix. All run numbers discussed in
this document are the revised test matrix run numbers. Run numbers were assigned based on the
set of prenumbered thermocouples and corresponding BDR used in the run. Runs are typically
discussed in the order in which they were conducted: 1, 2, 4, 8, 5, 6. Each variable tested is
discussed in further detail below.
2.3.1 Item Type
The BDR tested included %-inch thick, 4 feet by 8 feet sheets of LaFarge regular
grade drywall (wallboard), %-inch thick, 2 feet by 4 feet Armstrong Contractor Series Ceiling
Panels Model #942 (ceiling tiles), and Mannington Nepenthe II Blue commercial grade carpeting
(Nylon 6,6 fibers). New, unused wallboard and ceiling tiles were purchased from a building
material supplier. Used commercial carpeting, in rolls of varying sizes, was obtained from a
carpet installation contractor. Additionally, a used queen-sized sleeper sofa was obtained from a
thrift store.
Test material was cut up and packaged to simulate likely BDR generated from a
building decontamination scenario. Decontamination personnel are expected to size BDR to be
easily handled and pack it for shipment using a double-bagging technique. The techniques used
are similar to those from the State Department Sterling, Virginia mail facility anthrax cleanup
(2). The steps used to reduce the size and package each of these items are discussed below.
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Table 2-1. Originally Planned Healthcare Environmental Autoclave Test Matrix
Run
1
2
3
4
5
6
7
8
Item Type
Mixed, loose pack
Wallboard, dense
pack
Wallboard, dense
pack
Carpet
Ceiling tiles,
dense pack
Ceiling tiles,
dense pack
Carpet
Mixed, loose pack
Temp/
pressure
275°F/
31.5psig
275°F/
31.5psig
292°F/
45 psig
Select based
on runs 1, 2, 3
275°F/
31. 5 psig
292°F/
45 psig
Select based
on prior runs
292°F/
45 psig
Time
Target time at
250°F(121°C)for
all thermocouples is
15 minutes.
Provide a minimum
run time of 40
minutes. Extend run
time as needed to
achieve temperature
targets.
Position/Bin 1
Thermal Mass
(~7001bs)
Thermal Mass
(~7001bs)
Thermal Mass
(~7001bs)
Thermal Mass
(~7001bs)
Thermal Mass
(~7001bs)
Thermal Mass
(~7001bs)
Thermal Mass
(~7001bs)
Thermal Mass
(~7001bs)
Position/Bin 2
Loose Pack
CT, Dry
WB, Dry
-250 Ibs (10 TC)
Dense Pack
WB, Dry
-700 Ibs (12 TC)
Dense Pack
WB, Dry
-700 Ibs (12 TC)
Small rolls, loose
pack, wet and dry
-250 Ibs
(8TC)
Dense Pack
CT, Dry
-700 Ibs (12 TC)
Dense Pack
CT, Dry
-700 Ibs (12 TC)
Small rolls, loose
pack, wet and dry
-250 Ibs
(8TC)
Loose Pack
CT, Dry
WB, Dry
-250 Ibs (10 TC)
Position/Bin 3
Loose Pack
CT, Wet
WB, Wet
-300 Ibs (10 TC)
Dense Pack
WB, Wet
-850 Ibs (12 TC)
Dense Pack
WB, Wet
-850 Ibs (12 TC)
Small rolls,
dense pack
wet and dry -700
Ibs (8 TC)
Dense Pack
CT, Wet
-850 Ibs (12 TC)
Dense Pack
CT, Wet
-850 Ibs (12 TC)
Small rolls,
dense pack
wet and dry -700
Ibs (8 TC)
Loose Pack
CT, Wet
WB, Wet
-300 Ibs (10TC)
Position/Bin 4
Thermal Mass
(-700 Ibs)
Thermal Mass
(-700 Ibs)
Thermal Mass
(-700 Ibs)
Position/Bin 5
Carpet, small
rolls, dry (4 TC)
Open
Open
Large roll, wet (8 TC)
Thermal Mass
(-700 Ibs)
Thermal Mass
(-700 Ibs)
Open
Open
Large roll, wet (8 TC)
Sofa (4 TC)
Comments
Loose packing will provide one level of
bagged BDR in each bin. (6 x 40 Ib. bags)
Steam can easily penetrate to top and bottom
of all bags.
Similar to Run 1, but packing is denser,
approximately 3 to 4 levels deep (25 x 40 Ib.
bags per bin)
Similar to Run 2, but temperature is increased
to upper limit.
Test packing style and temperature profile
within carpet roll. Array thermocouples at
varying depths within rolls.
Similar to Run 2, ceiling tile instead of
wallboard
Similar to Run 5, temperature increased to
upper limit.
Test packing style and temperature profile
within carpet roll. Array thermocouples at
varying depths within rolls.
Similar to run 1, temperature at upper limit.
to
(x TC) designates "x" thermocouples per bin.
WB = Wallboard.
CT = Ceiling Tile.
CP = Carpet.
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Table 2-2. Healthcare Environmental Autoclave Test Matrix as Completed
Run
1
2
4
8
5
6
Original
Matrix
Run
1
3
4
8
Not
Included
Not
Included
Item Type
Mixed, loose
pack
Wallboard,
dense pack
Carpet
Mixed, loose
pack
Mixed, loose
vertical pack
Mixed, loose
vertical pack
Temp/
pressure
275°F/
31.5psig
292°F /
45 psig
275°F/
31.5 psig
292°F /
45 psig
275°F/
31. 5 psig
275°F/
31.5 psig
Time
120 min
120 min
120 min
75 min
2 cycles
each 40
min
2 cycles
each 40
min
Position/Bin 1
Thermal Mass
(~8001bs)
Thermal Mass
(~8001bs)
Thermal Mass
(~8001bs)
Thermal Mass
(~8001bs)
Thermal Mass
(~8001bs)
Thermal Mass
(~8001bs)
Position/Bin 2
Loose Pack
WB, Wet and Dry
-215 Ibs (10 TC)
Dense Pack
WB, Wet
-850 Ibs (12 TC)
Small rolls, dense
pack, wet and dry
-250 Ibs
(8TC)
Loose Pack
WB, Wet and Dry
-215 Ibs (10 TC)
Vertical Pack
CT, Wet and Dry
CP, Wet and Dry
-125 Ibs (12 TC)
Vertical Pack
CT, Wet and Dry
CP, Wet and Dry
-125 Ibs (12 TC)
Position/Bin 3
Loose Pack
CT, Wet and Dry
-170 Ibs (10 TC)
Dense Pack
WB, Dry
-750 Ibs (12 TC)
Small rolls,
loose pack
wet and dry -850 Ibs
(8TC)
Loose Pack
CT, Wet and Dry
-170 Ibs (10 TC)
Vertical Pack
CT, Wet and Dry
WB, Wet and Dry
-125 Ibs (12 TC)
Vertical Pack
CT, Wet and Dry
WB, Wet and Dry
-125 Ibs (12 TC)
Position/Bin 4
Carpet, small
rolls, dry
-150 Ibs (4 TC)
Thermal Mass
(-800 Ibs)
Position/Bin 5
Thermal Mass
(-800 Ibs)
Open
Large roll, wet (8 TC)
Sofa (4 TC)
Thermal Mass
(-800 Ibs)
Thermal Mass
(-800 Ibs)
Open
Open
Comments
One level of bagged BDR in each bin. (6 bags)
Steam could easily penetrate to top and bottom of
all bags; however, still took a considerable amount
of time.
Went directly to higher temperature (skipped
originally planned Run 2) because of the slow
heating of Run 1 .
Test packing style and temperature profile within
carpet roll. Array thermocouples at varying depths
within rolls.
Similar to run 1, temperature at upper limit. Run
time was terminated after 75 minutes due to
concern of the sofa temperature rising significantly
above the autoclave temperature, indicating the
potential initiation of exothermic reaction.
Test to determine if vertical packing and two
sequential shorter cycles would be effective.
Similar to Run 5, but all bags were cut.
to
(x TC) designates "x" thermocouples per bin.
WB = Wallboard.
CT = Ceiling Tile.
CP = Carpet.
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2.3.1.1 Wallboard
The wallboard was cut into approximately 2 feet by 2 feet sections as described in
the QAPP. Sample BDR bags were formed by placing five, 2 feet by 2 feet sections face to face
in autoclave bags. Samples requiring wetting were submerged in tank of water for 30 seconds
and placed on a drain rack for 5 minutes prior to being placed in the bag. Dry test bags weighed
approximately 34 pounds, and wet bags weighed approximately 37 pounds. Samples were
double bagged in 1.8 mil polypropylene autoclave bags, and the bags were individually goose-
necked and taped shut using duct tape. A section of nylon rope was attached to the gooseneck to
allow ERG personnel to easily and safely load and unload the bags from the autoclave bins.
Three types of wallboard bags were created. Some test bags were assembled
with one thermocouple and one test strip pouch placed together, between the second and third
wallboard section. These are referred to as "1-sample" bags. Other test bags were assembled
with three thermocouples paired with three test strip pouches placed between the first and
second, second and third, and fourth and fifth wallboard sections. These are referred to as "3-
sample" bags. Photographs 2 through 8 in Appendix A show how the bags were assembled.
Additional bags were made without thermocouples and BI test pouches to be used as fillers when
packing the autoclave bins.
Bags were placed in the autoclave bins in either a loose packing or dense packing
arrangement as indicated on the test matrix in Table 2.2. In the loose packing arrangement, six
bags were placed per bin: two 3-sample bags and four 1-sample bags. Ten total samples were
collected per bin in loose density packing. See Photograph 27 for the loose packing arrangement
of wallboard bags.
In the dense-packing arrangement, 23 bags were placed in each bin including
three, 3-sample bags and three 1-sample bags. The remaining 17 bags were used to fill out the
load. Bags were layered within the bin, in approximately three to four layers of four to six bags
each. Bags were placed in the bin with one 3-sample and one 1-sample bag in each layer, so that
sample bags were dispersed throughout the loaded bin. Twelve total samples were collected per
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bin in the dense packing arrangement. See the side view sketch in Figure 2-1 and Photograph 29
dense packing arrangement of bags.
For the vertical packing arrangement, one dry 3-sample and one wet 3-sample bag
were placed in a bin. Ropes tied to opposite edges of the autoclave bin wall were used to
maintain the vertical alignment, as shown in Photograph 35.
Figure 2-1. Side View Sketch of Dense Packing Arrangement
2.3.1.2
Ceiling Tiles
Ceiling tiles were cut into approximately 2 feet by 2 feet sections as described in
the QAPP. Samples were prepared similarly to wallboard; however, bags contained nine 2 feet
by 2 feet sections placed face to face. Dry test bags weighed approximately 23 pounds, and wet
bags weighed approximately 31 pounds.
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One-sample bags contained one thermocouple and one test strip pouch placed
together, between the fourth and fifth ceiling tile section. Three-sample bags contained three
thermocouples paired with three test strip pouches placed between the second and third, fourth
and fifth, and seventh and eighth ceiling tile sections. Additional bags were made without
thermocouples and BI test pouches to be used as fillers.
As discussed previously, originally planned runs of densely packed ceiling tiles
were deleted from the test matrix. In the loose packing arrangement, two 3-sample bags and four
1-sample bags were placed per bin. Ten total samples were collected per bin in loose density
packing. See the Photograph 30 for the loose packing arrangement of bags.
For the vertical packing arrangement, one dry 3-sample and one wet 3-sample bag
were placed in a bin. Ropes tied to opposite edges of the autoclave bin wall were used to
maintain the vertical alignment, as shown in Photograph 35.
2.3.1.3 Carpet
Carpet was tested in two general configurations, small and large rolls. For small
rolls, the contractor cut the carpet into strips 26 inches wide by 20 feet long, representing how
carpet would most likely be removed from a building. Samples requiring wetting were soaked
with a hose-end sprayer. After wetting, samples were rolled and placed on end to allow free-
flowing water to drain. Small rolls were bagged in a similar manner to wallboard and ceiling
tiles. Dry test bags weighed approximately 26 pounds, and wet bags weighed approximately 40
pounds. As a worst case, larger sections of carpet 6 feet wide and 24 feet long also were
requested and obtained from the contractor. Large rolls were only prepared wet, and weighed
approximately 200 pounds, which represented the maximum size that could be handled by two
workers. Large rolls were wrapped in polypropylene and all seams sealed with duct tape.
Photographs 10 through 15 in Appendix A show the assembly process for carpet bags.
For the small carpet rolls, 1- and 3-sample bags were prepared. One-sample bags
contained one thermocouple and one test strip pouch placed together, at the approximate mid-
point of the radius of the carpet roll. Three-sample bags contained three thermocouples paired
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with three test strip pouches placed two laps in from the top, at the mid-point of the radius, and
two laps from the center of the carpet roll. Additional bags were made without thermocouples
and BI test pouches to be used as fillers.
Bags with small rolls of carpet were placed in the autoclave bins in either a loose
packing or dense packing arrangement. In the loose packing arrangement, two, 3-sample bags
and two, 1-sample bags were placed in a bin. Bags that did not contain sample points were used
to fill out the load. Eight total samples were collected per bin in the loose packing arrangement.
In the dense packing arrangement, shown in Photograph 33, 25 bags were placed
per bin including two 3-sample bags and two 1-sample bags. The remaining 21 bags were used
to fill out the load. Bags were layered within the bin, in approximately three to four layers of six
to eight bags each. Bags were placed in the bin so that two 3-sample bags were placed in the
middle layer and two 1-sample bags were placed in the bottom layer. Eight total samples were
collected per bin in the dense packing arrangement.
For the vertical packing arrangement, one dry 3-sample and one wet 3-sample bag
were placed in a bin. Ropes tied to opposite edges of the autoclave bin wall were used to
maintain the vertical alignment, as shown in Photograph 35.
The large roll of carpet was assembled with eight thermocouples paired with eight
test strip pouches placed at eight locations throughout the roll. The locations were arrayed
progressively deeper within the rolled carpet, as depicted in Figure 2-2. The large roll of carpet
was placed in the autoclave on a wood pallet rather than in a bin, as shown in Photograph 34.
2-9
-------
Center of Carpet Roll
Sample Point
2.3.1.4
Figure 2-2. Configuration of Sample Points in a Large Carpet Roll
Sofa
A used queen-sized sleeper sofa was obtained from a thrift store and autoclaved in
Run 4. The sofa was not wetted prior to being autoclaved. Four thermocouple and test strip
pouches were paired and embedded in different locations in the sofa. Samples were inserted in
holes cut approximately 6 inches deep in a back cushion and a seat cushion. The holes were then
covered with duct tape. One sample was also placed in between the folded sleeper mattress, and
one in between the seat cushions. The sofa was wrapped in polypropylene and all seams sealed
with duct tape, as shown in Photograph 16. The sofa was placed in the autoclave on a sheet of
plywood.
2.3.2
Autoclave Packing Density
The Healthcare Environmental autoclave is designed to operate with six loaded
bins of material, loaded with approximately 700 pounds of material each.
Wallboard was tested at two different bin packing densities. Low density packing
involved placing six bags in a bin. In a low density arrangement, shown in Photograph 27, the
2-10
-------
bags formed a single layer at the base of the bin, and all bag surfaces were readily exposed to
autoclave temperatures. High density packing, shown in Photograph 29, involved placing 23
bags in each bin. The bags were layered approximately three to four levels deep, exposing some
bags directly to autoclave conditions while others were buried within the load in the bin. Ceiling
tiles were only tested in a low density arrangement, as described above for wallboard. Runs of
densely packed ceiling tiles were deleted from the test matrix because densely packed BDR
material could not be brought up to autoclave temperatures within the 120-minute duration
specified in the test plan.
Carpet was tested in three configurations. Small rolls, approximately 1 foot in
diameter and 26 inches long, were placed in bags. Six bags were placed in a bin for low density
packing, as above (see Photograph 31). Twenty-five bags were placed in a bin for high density
packing, as above (see Photograph 33). In addition, the effect of the autoclave on a large, intact
roll of carpet 6 feet long and approximately 1.5 feet in diameter, shown in Photograph 34, was
tested in Run 4.
2.3.3 Moisture Content
Materials were tested both dry and wet. In this context, dry means in as-is
condition at ambient humidity, with no additional moisture added. Wet conditions were created
by briefly immersing wallboard and ceiling tile pieces in water and allowing them to drain.
Immediately after draining, the wallboard and ceiling tiles were placed in sealed polyethylene
bags. Carpet was soaked with a hose-end sprayer until saturated, and then allowed to drain.
After draining, carpet pieces were rolled up and sealed in either polyethylene bags (small rolls)
or wrapped in polyethylene sheeting (large rolls). Wet and dry bags of BDR were weighed to
determine the additional water weight. On average, wetting increased the weight of wallboard
bags by 9 percent, ceiling tile bags by 34 percent, and carpet bags by 53 percent.
2.3.4 Temperature and Pressure
Temperature and pressure are related variables, as the autoclave is designed to
operate at saturated steam conditions. The study investigated two conditions: 31.5 psig / 275°F,
2-11
-------
the typical operating pressure of the autoclave, and 45 psig / 292°F, the maximum operating
pressure of the autoclave. Pressure is the parameter controlled by the autoclave controller.
These temperatures and pressures are as measured in the interior space of the autoclave.
Temperatures within the autoclaved items lagged behind these temperatures, as discussed in
Section 2.3.5.
2.3.5 Time
A minimum run time of 40 minutes at elevated temperature was established,
according to standard operation of the Healthcare Environmental autoclave. Literature data
indicate that 15 minutes at 250°F is required for assured moist heat sterilization (3,4). Therefore,
the test plan called for extending the run time beyond 40 minutes to achieve a 250°F temperature
target at all, or at least most embedded thermocouples. Even if the 250°F target had not been
achieved, the test plan established a maximum run time of 120 minutes to enable the autoclave to
process multiple test runs each day. Runs 1, 2, and 4 were terminated after 120 minutes, prior to
all thermocouples reaching the target temperature. Run 8 was stopped after 75 minutes due to
concerns that the sofa temperature was rising above the temperature of the autoclave, indicating
a potential exothermic reaction in the sofa. Because such a reaction and possible associated
hazards were not well understood, the run was terminated. Conducting two 40-minute runs in
sequence was investigated in Runs 5 and 6. This variation is discussed further in Section 2.3.8.
2.3.6 Packing Orientation
Material was tested both lying horizontally in the autoclave bins and positioned
vertically, with all sides exposed. Material was positioned vertically by tying two ropes to the
top of the bag and attaching the ends of the rope to opposite sides of the autoclave bin wall, as
shown in Photograph 35. This packing orientation was introduced as a test variable to simulate
using a rack system to position bags so that all sides are exposed to autoclave steam. We
theorized that vertical orientation of the BDR would reduce compression from its own weight,
and also would allow steam condensate to drain more easily as it formed. If these theories are
correct, both would facilitate steam penetration and improve heating of the material in the
autoclave.
2-12
-------
2.3.7 Open Bags
All BDR was double-bagged in 1.8 mil polypropylene bags. The bags were
individually goose-necked and sealed with duct tape. This procedure was adopted based on
packaging information from the State Department Sterling, Virginia mail facility anthrax cleanup
(2). After autoclaving, some of the bags had clearly ruptured due to temperature and pressure
changes. However, in many cases bag surfaces bubbled and became deformed in the autoclave,
but it was not clear if they had fully opened. To test if the bags opening had an effect on
sterilization, two bags in Run 5 and all of the bags in Run 6 were opened prior to autoclaving, by
slicing two sides of each bag open with a utility knife across their entire length.
2.3.8 Multiple Short Cycles
As steam in the autoclave was evacuated to end Runs 2, 4, and 8, the test team
observed that, as the vacuum was drawn, most thermocouple readings converged toward a mid-
point temperature. Not only were high readings falling, but most of the lower readings were
rising and converged together. It is not known if this was a result of increased turbulence during
the post-vacuum cycle, condensed water being drawn out of BDR under vacuum, or some
combination of these and other factors. However, in consultation with EPA WAM, we decided
that it would be worthwhile to further investigate this phenomenon. Therefore, in Runs 5 and 6,
two complete normal autoclave operating cycles were run in succession. Each cycle consisted of
a pre-vacuum, steam pressurization, and post-vacuum phase. The cycles were conducted in
immediate succession and the autoclave remained sealed throughout both cycles.
2.4 Test Schedule
ERG conducted BDR size reduction, wetting, sample placement, and packaging at
its Chantilly, Virginia facility between February 15 and February 24, 2005. Materials were
stored at room temperature until March 1, 2005.
2-13
-------
Materials were placed on truck trailers on March 1, 2005 and transported to
Oneonta, New York by Roadway Express, Inc. Trailers were delivered in Oneonta on March 3,
2004. ERG sealed the trailers in Chantilly, and broke the seals in Oneonta.
Test materials were unloaded and staged for processing on March 4, 2005, and
autoclaved on March 5 and 6, 2005.
2-14
-------
s.o RESULTS
This section presents the time/temperature, biological indicator, and quality
assurance data collected during this test. Section 4 presents the analysis of the data.
3.1 Time/Temperature Data
Real-time temperature measurements were monitored and recorded at each
sampling point using a GEC Instruments Model S27TC temperature measurement system and
Type "T" thermocouples. Figures 3-1 through 3-6 (located at the end of this section) present
plots of the time/temperature data recorded during each of the six runs. Temperature data were
recorded at each location approximately every 10 seconds. The figures also include readings
from the control thermocouple inside the autoclave, the reference thermocouple outside the
autoclave, and the autoclave set point pressure/temperature. Note that Figures 3-1 through 3-6
are designed to present an overview of all time/temperature data associated with each run.
Section 4.0 provides further analysis of these data and distinction between the variables.
The facility monitoring system collected additional process measurement data.
Operating temperature and pressure within the autoclave were measured using the existing
autoclave thermocouple and pressure gauge and synchronized against 24-hour clock time. The
time, temperature, and pressure were recorded during the test on a 24-hour circular chart
recorder.
3.2 Biological Indicator Data
A BI test pouch, containing two BI test strips, was placed at each sampling point.
Each BI strip contained a 106 population of Geobacillus stearothermophilus on Schleicher &
Schuell filter paper (#470) encased in a glassine peel-open envelope. The test pouch consisted of
medical grade paper with a plastic facing. Raven Biological Laboratories, Inc. (Raven) provided
the BI pouches (American Type Culture Collection #7953, Lot #3167091, expiration January
2007). The strips within each pouch were designated 'A' strips and 'B' strips. Following the
test, Raven cultured all A strips for an indication of growth or no-growth. For A strips indicating
3-1
-------
growth, Raven performed a population assay of the B strip to quantify the survivor population.
Table 3-1 presents the results from these analyses.
3.3 Quality Assurance Data
This section presents quality assurance data collected and compares all data
collected with the acceptance criteria presented in Section 7.0 of the QAPP.
3.3.1 Process Measurements
Autoclave temperature, autoclave pressure, and run time were recorded on a 24-
hour circular chart recorder. Record data where accurate to the following levels, meeting the
acceptance criteria:
• Autoclave temperature: ± 5°F
• Autoclave pressure: ±0.5psig
• Run time: ± 1 minute
3.3.2 Experimental Measurements
Quality data for each of the experimental measurements are presented in the
following subsections.
3.3.2.1 Run Time
The temperature logging system was synchronized to ± 1 minute with the
autoclave data recorder clock at the beginning of each day. All time/temperature data was time
stamped to ± 1 second. All data was time stamped and therefore is considered usable.
5-2
-------
Table 3-1. Biological Indicator Data
Run
Number
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Thermocouple
Number
101
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
115
116
117
118
119
120
121
122
123
124
125
Material Type
(WB = Wallboard,
CT = Ceiling Tiles,
CP= Carpet)
WB
WB
WB
WB
WB
WB
CT
CT
CT
CT
CT
WB
WB
WB
WB
WB
WB
CT
CT
CT
CT
CT
CP
CP
CP
CP
N/A
Moisture
Content
(W = Wet,
D = Drv)
D
D
D
D
D
D
D
D
D
D
D
W
W
W
W
W
W
W
W
W
W
W
D
D
D
D
N/A
Depth in
Bin
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
N/A
Packing Density/ Additional
Notes
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Control Inside Autoclave
BI Test Pouch
Number
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
165
166
167
168
217
Type of BI Control
Sample
Duplicate
Duplicate
Run 1 Full Exposure
Control
Growth/No
Growth Result
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
Population
Assay Result
(CFU)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
-------
Table 3-1 (Continued)
Run
Number
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Thermocouple
Number
201
202
203
204
204
205
206
207
208
209
210
211
212
213
214
215
216
217
217
218
219
220
221
222
223
224
225
Material Type
(WB = Wallboard,
CT = Ceiling Tiles,
CP= Carpet)
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
WB
N/A
Moisture
Content
(W = Wet,
D = Drv)
D
D
D
D
D
D
D
D
D
D
D
D
D
W
W
W
W
W
W
W
W
W
W
W
W
W
N/A
Depth in
Bin
B
T
M
M
M
M
M
T
T
T
B
B
B
T
M
B
B
B
B
B
T
T
T
M
M
M
N/A
Packing Density/ Additional
Notes
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Control Inside Autoclave
BI Test Pouch
Number
1
2
3
4
13
5
6
7
8
9
10
11
12
66
67
68
69
72
70
71
73
74
75
76
77
78
218
Type of BI Control
Sample
Duplicate
Duplicate
Run 2 Full Exposure
Control
Growth/No
Growth Result
No Growth
No Growth
No Growth
No Growth
No Growth
Growth
Growth
Growth
Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
Growth
No Growth
No Growth
Growth
Growth
Growth
Growth
Growth
Growth
Growth
Population
Assay Result
(CFU)
N/A
N/A
N/A
N/A
N/A
183,000
220,000
150,000
61,000
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
<100
N/A
N/A
283,000
9,330
13,000
47,300
13,000
39,700
330
-------
Table 3-1 (Continued)
Run
Number
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Thermocouple
Number
401
402
403
404
405
406
407
408
409
410
411
411
412
413
414
415
416
417
418
419
420
420
421
422
423
424
425
Material Type
(WB = Wallboard,
CT = Ceiling Tiles,
CP= Carpet)
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
CP
N/A
Moisture
Content
(W = Wet,
D = Drv)
W
W
W
W
W
W
W
W
D
D
D
D
D
D
D
D
D
W
W
W
W
W
W
W
W
W
N/A
Depth in
Bin
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
B
B
B
B
B
M
B
B
B
B
B
B
B
B
M
T
T
T
N/A
Packing Density/ Additional
Notes
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Dense Pack
Dense Pack
Dense Pack
Dense Pack
Control Inside Autoclave
BI Test Pouch
Number
136
137
138
139
140
141
142
143
169
170
171
172
173
174
175
176
177
187
188
189
190
191
192
193
194
195
219
Type of BI Control
Sample
Duplicate
Duplicate
Run 4 Full Exposure
Control
Growth/No
Growth Result
Growth
Growth
Growth
Growth
Growth
Growth
Growth
Growth
No Growth
Growth
Growth
Growth
Growth
Growth
Growth
Growth
Growth
Growth
No Growth
No Growth
No Growth
No Growth
Growth
Growth
Growth
No Growth
No Growth
Population
Assay Result
(CFU)
63,700
370,000
473,000
131,000
140,000
277,000
280,000
113,000
N/A
72,000
54,300
13,700
100
117,000
537,000
197,000
347,000
<100
N/A
N/A
N/A
N/A
100,000
18,300
80,000
N/A
N/A
-------
Table 3-1 (Continued)
Run
Number
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
Thermocouple
Number
801
802
803
804
805
806
807
808
809
810
810
811
812
812
813
814
815
816
817
818
819
820
821
822
823
824
825
Material Type
(WB = Wallboard,
CT = Ceiling Tiles,
CP= Carpet)
WB
WB
WB
WB
WB
CT
CT
CT
CT
CT
CT
WB
WB
WB
WB
WB
WB
CT
CT
CT
CT
CT
Couch
Couch
Couch
Couch
N/A
Moisture
Content
(W = Wet,
D = Drv)
D
D
D
D
D
D
D
D
D
D
D
W
W
W
W
W
W
W
W
W
W
W
D
D
D
D
N/A
Depth in
Bin
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
N/A
N/A
N/A
N/A
N/A
Packing Density/ Additional
Notes
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
Loose Pack - Horizontal
N/A
N/A
N/A
N/A
Control Inside Autoclave
BI Test Pouch
Number
101
102
103
104
105
106
107
108
109
110
111
112
114
113
115
116
117
118
119
120
121
122
213
214
215
216
220
Type of BI Control
Sample
Duplicate
Duplicate
Run 8 Full Exposure
Control
Growth/No
Growth Result
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
Population
Assay Result
(CFU)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
<100
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
-------
Table 3-1 (Continued)
Run
Number
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
Thermocouple
Number
501
502
503
504
505
505
506
507
508
509
510
511
512
513
514
515
516
517
518
518
519
520
521
522
523
524
525
Material Type
(WB = Wallboard,
CT = Ceiling Tiles,
CP= Carpet)
WB
WB
WB
CT
CT
CT
CT
WB
WB
WB
CT
CT
CT
CP
CP
CP
CP
CP
CP
CP
CT
CT
CT
CT
CT
CT
N/A
Moisture
Content
(W = Wet,
D = Drv)
W
W
W
W
W
W
W
D
D
D
W
W
W
W
W
W
D
D
D
D
D
D
D
D
D
D
N/A
Depth in
Bin
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Packing Density/ Additional
Notes
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Uncut
Vertical - Uncut
Vertical - Uncut
Control Inside Autoclave
BI Test Pouch
Number
159
160
161
43
44
45
46
130
131
132
50
51
52
202
203
204
179
180
181
182
60
61
62
63
64
65
221
Type of BI Control
Sample
Duplicate
Duplicate
Run 5 Full Exposure
Control
Growth/No
Growth Result
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
Growth
Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
Population
Assay Result
(CFU)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
500
470
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
-------
Table 3-1 (Continued)
Run
Number
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
Thermocouple
Number
601
602
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
616
617
618
619
620
621
623
624
625
626
Material Type
(WB = Wallboard,
CT = Ceiling Tiles,
CP= Carpet)
WB
WB
WB
WB
CT
CT
CT
WB
WB
WB
CT
CT
CT
CP
CP
CP
CT
CT
CT
CT
CP
CP
CP
N/A
CT
CT
CT
Moisture
Content
(W = Wet,
D = Drv)
W
W
W
W
D
D
D
D
D
D
D
D
D
W
W
W
W
W
W
W
D
D
D
N/A
W
W
W
Depth in
Bin
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Packing Density/ Additional
Notes
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Vertical - Cut
Control Inside Autoclave
Vertical - Cut
Vertical - Cut
Vertical - Cut
BI Test Pouch
Number
147
148
149
150
17
18
19
133
134
135
24
25
26
198
199
200
30
31
32
33
184
185
186
222
37
38
39
Type of BI Control
Sample
Duplicate
Duplicate
Run 6 Full Exposure
Control
Growth/No
Growth Result
Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
No Growth
Population
Assay Result
(CFU)
<100
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
<100
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
-------
Table 3-1 (Continued)
Run
Number
Control
Control
Control
Control
Control
Control
Control
Control
Control
Thermocouple
Number
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Material Type
(WB = Wallboard,
CT = Ceiling Tiles,
CP= Carpet)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Moisture
Content
(W = Wet,
D = Drv)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Depth in
Bin
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Packing Density/ Additional
Notes
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
BI Test Pouch
Number
205
206
207
208
209
210
211
212
223
Type of BI Control
Sample
Negative Control - Dry
Wallboard
Negative Control - Wet
Wallboard
Negative Control - Dry
Ceiling Tiles
Negative Control - Wet
Ceiling Tiles
Negative Control - Dry
Carpet
Negative Control - Wet
Carpet
Negative Control - Dry
Empty Bag
Negative Control - Wet
Empty Bag
Negative Control - Dry
Empty Bag
Growth/No
Growth Result
Growth
Growth
Growth
Growth
Growth
Growth
Growth
Growth
Growth
Population
Assay Result
(CFU)
1,200,000
1,670,000
1,270,000
1,800,000
1,300,000
703,000
990,000
1,430,000
843,000
N/A - Not applicable.
-------
3.3.2.2 Temperature
All thermocouples were checked for quality using the procedure outlined in
Section 6.3 of the QAPP prior to the test. All thermocouples met the acceptance criteria and
were accurate to within ± 0.7°F compared to a known reference thermometer. Reference testing
was conducted at 275°F.
Thermocouples placed into each load were connected to a data logger through a
27-channel interface device. The thermocouple at each sample location was uniquely numbered
using a system where the last two digits ran in a sequence from 01 to 24. Channels 25, 26, and
27 were used as spares or controls. Numbered thermocouples were connected in the same
sequence to corresponding data logging channels. For example, thermocouple 101 was
connected to channel 01, 102 to 02, and so forth. The instrumentation technician made the
connections, which were verified by the ERG test director.
One thermocouple channel was used to monitor ambient conditions outside the
autoclave to verify the data acquisition system was functioning properly. This temperature
stayed relatively constant throughout each run, varying between 60 and 75°F. A thermocouple
also was mounted near the top of one of the autoclave bins in each run, fully exposed to
autoclave conditions. These data tracked closely with the process temperature measurements for
all runs except Run 2. The thermocouple reading for the fully exposed autoclave temperature in
Run 2 (thermocouple 225) suddenly dropped approximately 20°F, 18 minutes into cycle. After
the autoclave cycle was complete, the thermocouple and corresponding BI test pouch were found
to have fallen from their mount on the autoclave bin wall into the bulk of BDR mass being
tested. For all subsequent runs, the thermocouple was mounted using a c-clamp rather than duct
tape, and a second control thermocouple was placed near the bottom of the bin so that fully
exposed thermocouples were placed near the top and toward the bottom of an autoclave bin.
Note that a fully exposed control BI test pouch was only placed next to the top control
thermocouple. Fully exposed control thermocouple readings were consistent with process
temperature readings on all subsequent runs.
3-10
-------
During the runs, thermocouples 102, 401, and 423 failed and either stopped
providing a signal or sent negative temperature readings. Significant signal noise was also
observed in thermocouples 108, 117, 118, 121, and 814. During Run 1, condensate from steam
that traveled inside the sheathed thermocouple wire collected on the thermocouple connectors
outside the autoclave. The condensate collecting within the connectors likely caused the signal
noise and in some cases failure of the thermocouples in Run 1. After Run 1, the connectors were
inverted to force the condensate to drip off the wires instead of collecting in the connectors,
which eliminated most of the signal noise and failure problems. Of the 162 time/temperature
data series, 156 were collected satisfactorily, resulting in 96 percent complete data. Therefore,
the acceptance criteria of at least 80 percent of the data being collected satisfactorily was met.
No data from the three thermocouples that failed were used for the analyses in this
report. Data from the five thermocouples with significant noise were used. Most of the noise
resulted in abrupt temperature spikes or dips of less than 50°F. However, there were two data
spikes for thermocouple 118 where the temperature reading more than doubled for
approximately 20 seconds. This is characteristic of no signal being received by the data logger
for a short period. Data from the data point immediately preceding the spikes were extrapolated
and used for data analyses instead of the temperature spike data for these two instances for
thermocouple 118. All other temperature data were used as recorded.
3.3.2.3 Test Conditions
The ERG test engineer recorded the test conditions on log sheets as identified in
the QAPP. The ERG test engineer and ERG test director verified and signed all log sheets for
each run.
3.3.2.4 BI Test Strip Results
Raven Biological Laboratories, Inc. analyzed the BI test strips. All samples were
successfully analyzed, providing alOO percent complete data set.
3-11
-------
Three sets of control BI pouches were analyzed. First, two duplicate sample
pouches were placed within each test run, adjacent to the sample pouch it was duplicating. Of
the 12 duplicate pouches, 10 yielded the same results as the corresponding sample pouches (i.e.,
growth was found in both in one case and no growth was found in both in nine cases). However,
at two of the sample points (thermocouples 217 and 812) the growth/no-growth results for the
duplicates did not match (i.e., the 'A' strip for the duplicate indicated growth and the 'A' strip
for the sample did not). The 'B' strips for the duplicates were assayed and no viable survivor
population was found (<100 CPU), consistent with the A strip of the original sample. These data
suggest that, in some cases, a growth indication alone may be a false positive result (2 of the 12
cases measured). However, the growth/no-growth indication coupled with the BI assay data is a
reliable measure of sterilization and spore viability.
Additionally, nine blind control samples were analyzed that were not exposed to
autoclave conditions, but in all other respects handled the same as other BI test pouches. These
nine controls all yielded positive results for growth, and the assay data confirm that no
significant reduction in viable spores was caused by the handling, packaging, and shipping of the
BI pouches.
Finally, one blind control test pouch was autoclaved in each run, not embedded in
any building material and exposed fully to autoclave conditions. These controls for all runs
except Run 2 yielded negative results for growth. Upon analyzing the assay data for the Run 2
control, only a 104 reduction in viable spores was achieved. As mentioned previously, the
thermocouple and corresponding BI test pouch for Run 2 fell from their mount on the autoclave
bin wall and became embedded in the BDR mass in Run 2. This caused the BI test pouch not to
be fully exposed to the autoclave conditions and is likely the cause of the remaining spore
viability. No growth was observed in every other quality assurance sample fully exposed
throughout the test.
3-12
-------
Run1 -31.5psig/275°F
Multiple BDR Types
Loose Pack
LL 230 -
1
£ 190
20
40
80
100
60
Time (min)
Figure 3-1. Run 1 Time/Temperature Data
DWB - Dry Wallboard; WWB - Wet Wallboard; DCT - Dry Ceiling Tiles; WCT - Wet Ceiling Tiles; DCP - Dry Carpet; CON - Fully
Exposed Control; REF - Exterior Reference Temperature
120
•101 DWB
•103 DWB
•104 DWB
105 DWB
•106 DCT
•107 DCT
•108 DCT
109 DCT
110 DCT
111 WWB
112WWB
113WWB
114 WWB
115 WWB
•116 WCT
•117 WCT
118 WCT
119 WCT
120 WCT
•121 DCP
•122 DCP
123 DCP
124 DCP
•125 CON
•126 REF
-------
310
290
270
Run 2 - 45psig/292°F
Wallboard - Dense Pack
70
50
20
40
100
120
140
60 80
Time (min)
Figure 3-2. Run 2 Time/Temperature Data
DWB - Dry Wallboard; WWB - Wet Wallboard; T - Top of Dense Pack Bin; M - Middle of Dense Pack Bin; B - Bottom of Dense Pack Bin
CON - Fully Exposed Control; REF - Exterior Reference Temperature
•201 DWB-B
•202 DWB-T
203 DWB-M
204 DWB-M
205 DWB-M
206 DWB-M
207 DWB-T
208 DWB-T
209 DWB-T
•210 DWB-B
•211 DWB-B
•212 DWB-B
•213WWB-T
•214 WWB-M
•215 WWB-B
•216WWB-B
•217 WWB-B
•218 WWB-B
•219WWB-T
•220 WWB-T
•221 WWB-T
222 WWB-M
•223 WWB-M
224 WWB-M
•225 CON
•226 REF
-------
Run4-31.5psig/275°F
Carpet - Loose, Dense, and
Large Roll
20
40 60 80 100
Time (min)
Figure 3-3. Run 4 Time/Temperature Data
120
140
•402 WCP Roll
•403 WCP Roll
•404 WCP Roll
•405 WCP Roll
406 WCP Roll
407 WCP Roll
408 WCP Roll
•409 DCP Loose
•410 DCP Loose
411 DCP Loose
412 DCP Loose
413DCPDense-M
414 DCP Dense-B
415 DCP Dense-B
416 DCP Dense-B
•417 WCP Loose
•418 WCP Loose
•419 WCP Loose
420 WCP Loose
•421 WCP Dense-M
422 WCP Dense-T
424 WCP Dense-T
•425 CON
•426 REF
DCP - Dry Carpet; WCP - Wet Carpet; Roll - Large Carpet Roll; T - Top of Dense Pack Bin; M - Middle of Dense Pack Bin; B - Bottom of
Dense Pack Bin CON - Fully Exposed Control; REF - Exterior Reference Temperature
-------
Run 8 - 45psig/292°F
Multiple BDR Types
Loose Pack
50
20
40
60
80
Time (min)
Figure 3-4. Run 8 Time/Temperature Data
DWB - Dry Wallboard; WWB - Wet Wallboard; DCT - Dry Ceiling Tiles; WCT - Wet Ceiling Tiles; CON - Fully Exposed Control; REF •
Exterior Reference Temperature
•801 DWB
•802 DWB
•803 DWB
804 DWB
805 DWB
•806 DCT
•807 DCT
•808 DCT
809 DCT
810 DCT
811 WWB
812 WWB
813 WWB
814 WWB
815 WWB
•816 WCT
•817 WCT
818 WCT
819 WCT
820 WCT
•821 SOFA
•822 SOFA
823 SOFA
824 SOFA
•825 CON
•827 REF
-------
Run5-31.5psig/275°F
Multiple BDR Types
Vertical - Two Cycles
50
10
20
30
70
80
90
40 50 60
Time (min)
Figure 3-5. Run 5 Time/Temperature Data
DWB - Dry Wallboard; WWB - Wet Wallboard; DCT - Dry Ceiling Tiles; WCT - Wet Ceiling Tiles; DCP - Dry Carpet;
WCP - Wet Carpet; CON - Fully Exposed Control; REF - Exterior Reference Temperature
100
•501 WWB
•502 WWB
503 WWB
•504 WCT
•505 WCT
•506 WCT
•507 WWB
•508 WWB
509 WWB
•510 WCT
•511 WCT
512 WCT
513 WCP
514 WCP
515 WCP
516 DCP
517 DCP
518 DCP
•519 DCT
•520 DCT
•521 DCT
•522 DCT
523 DCT
524 DCT
•526 CON
•527 REF
-------
oo
50
Run6-31.5psig/275°F
Multiple BDR Types - Vertical
Two Cycles - All Bags Cut
10
20
30
50
60
70
40
Time (min)
Figure 3-6. Run 6 Time/Temperature Data
DWB - Dry Wallboard; WWB - Wet Wallboard; DCT - Dry Ceiling Tiles; WCT - Wet Ceiling Tiles; DCP - Dry Carpet;
WCP -Wet Carpet; CON - Fully Exposed Control; REF - Exterior Reference Temperature
80
•601 WWB
•602 WWB
603 WWB
•604 DCT
•605 DCT
•606 DCT
•607 DWB
•608 DWB
609 DWB
•610 DCT
611 DCT
612 DCT
613 WCP
614 WCP
615 WCP
•616 WCT
•617 WCT
•618 WCT
619 DCP
620 DCP
621 DCP
•623 CON
•624 WCT
•625 WCT
626 WCT
•627 REF
-------
4.0 DISCUSSION
As discussed previously, the following variables were identified as having a
potential impact on sterilization capability:
1. Item type;
2. Autoclave packing density (i.e., loose packing versus dense packing);
3. Moisture content of autoclaved materials;
4. Autoclave temperature/pressure; and
5. Time in autoclave.
During the test, three additional factors were identified as potentially influencing
sterilization capability:
1. Positioning sample bags of BDR vertically instead of horizontally;
2. Cutting open the bags of BDR to facilitate steam penetration; and
3. Running two shorter process cycles in sequence instead of one long cycle.
One additional factor that may affect sterilization not investigated in this study
was the packaging technique. BDR was cut up, double bagged in 1.8 mil autoclave bags, and
goose-necked closed with duct tape, to mimic BDR generated from a likely disposal incident.
Other packaging techniques (e.g., bag/container type, bag thickness, quantity of BDR per bag,
and sealing method) that may also influence sterilization ability were not evaluated.
This section first discusses the impact of the observed time/temperature profiles
on BDR sterilization, measured using the BI growth/no-growth and assay results. The section
then presents how each of the variables above affected the temperature profile and associated
sterilization results.
4.1 Time and Temperature Effect on Sterilization
Figures 4-1 through 4-3 present the time and temperature affect on sterilization
for Runs 2, 4, and 5. All figures are located at the end of this section. On each figure, the
time/temperature profile is plotted, and the lines are color coded to indicate whether the
4-1
-------
associated BI data indicated viable spores or no viable spores. A viable spore designation is used
if growth was found in both the growth/no-growth test and the assay analysis. Sterilization or a
no viable spore designation is used if no growth was found in the growth/no-growth test with an
106 initial BI population. In a limited number of cases, the growth/no-growth test indicated a
positive result; however, no quantifiable population was measured by the subsequent assay
analysis (reported result of <100 CPU). These data series are labeled as indeterminate.
No figures are provided for Runs 1, 8, and 6 because no viable spores were found
in these runs. The temperature profiles for these runs can be viewed on Figures 3-1,3-4, and 3-6,
respectively. Each of these runs contained loose pack BDR materials, processed at different
conditions.
The spores were sterilized in all cases where the target of 15 minutes at 250°F
was achieved. While spores were also sterilized in several instances below this target, 15
minutes at 250°F was required to ensure sterilization. The effect of each variable on sterilization
is discussed in the following subsections.
4.2 Item Type and Moisture Content
The temperature profiles for Runs 1, 8, 5, and 6, presented in Figures 4-4 through
4-7, respectively, show the influence of item type on temperature profile. Within each of these
runs, different item types were autoclaved under the same conditions. An average data series is
provided for each item type on each figure. The average data series were calculated as the
arithmetic average of the temperature at each time T, at every sampling location of that type. For
example, in Run 1, there were five wet ceiling tile sampling locations. The temperature plotted
for the wet ceiling tile series at T = 20 minutes is the average of the temperatures at each of the
five wet ceiling tile locations at T = 20 minutes. Where averages were calculated, the number of
sample points averaged is presented next to each series.
As shown on the figures, dry carpet and dry ceiling tiles heated more rapidly than
wet carpet and wet ceiling tiles, respectively. Dry wallboard and wet wallboard heated at
approximately the same rate in three of the four runs where comparison can be made (Figures 4-
4-2
-------
4, 4-5, 4-7). In Run 5 (Figure 4-6), the wet wallboard heated significantly faster. These
differences are believed to be functions of the moisture content of each material. The difference
between dry and wet carpet and ceiling tile results are likely due to the significant water
absorbing-capacity of carpet (53 percent increase in weight when wet) and ceiling tiles (34
percent increase in weight when wet). The significant water content of the wet carpet and ceiling
tiles increases the thermal load needed to boil the water and heat the material in the autoclave
and may also decrease steam penetration.
Wallboard does not absorb as much water when wet (9 percent increase in weight
when wet). This would explain the relatively similar results for wet and dry wallboard observed
on Figures 4-4, 4-5, and 4-7.
With respect to differing item types, wet wallboard heated faster than wet ceiling
tiles, which heated faster than wet carpet. This relationship was observed in all runs and is
consistent with the relative water-absorbing capacity of each material, as discussed above. When
moisture content is eliminated as a variable and dry BDR items are compared to each other, there
is no apparent trend. For example, dry carpet heated fastest in Run 1, but slower than dry ceiling
tiles and dry wallboard in Run 6. Similarly, dry ceiling tiles heated fastest in Run 6, but slower
than dry wallboard and dry carpet in Run 5. These observations suggest that trends and
differences in heating rates between BDR item types depends primarily on the moisture content
of wet items, and not on the BDR material itself.
The sofa, tested dry, heated more rapidly than wallboard and ceiling tiles in the
one run where it was tested (Figure 4-5). If it had been saturated with water, the results may
have been significantly different, based on the findings for ceiling tiles and carpet.
4.3 Autoclave Packing Density and Location
The effect of autoclave packing density is best isolated from other variables by
examining the data for Runs 2, 4, and 8. Wet and dry wallboard were tested in both loose pack
(one layer of bags) and dense pack arrangement (approximately four layers of bags) in Runs 2
and 8, respectively. Both runs were conducted at 45 psig (292°F). Figure 4-8 presents average
4-3
-------
time/temperature profile data for each set of conditions. Carpet was tested in both a loose pack
and dense pack arrangement in Run 4 at 31.5 psig (275°F); Figure 4-9 presents average
time/temperature profile data. As shown by these figures, loose pack items heat significantly
faster than dense pack. Most of the dense pack sample points never achieved the target
temperature of 250°F for 15 minutes, and resulted in significant remaining spore viability (see
Figures 4-1 and 4-2). The majority of the positive growth results found during the test were in
the dense packing configuration.
The temperature profile within the thermal mass was investigated using data from
Run 2. Figure 4-10 presents average data from dense pack wallboard in Run 2 at varying levels
within the mass. Top layer data points are from thermocouples in bags at the top of the mass,
exposed to the autoclave conditions; middle layer data points are from bags in between other
bags; and bottom layer data point are from bags touching the bottom of the bin. As shown by
these data, the bags at the bottom of the bin heated fastest, indicating conduction through the
metal bin may be a factor in heating the BDR. However, remaining viable spores were found in
all three layers of densely packed material.
Selected wallboard bags were examined to investigate the temperature profile
within the 3-sample bags. Figure 4-11 presents two examples, comparing the temperature profile
within a dry loose pack wallboard bag and a dry dense pack, middle layer wallboard bag. As
shown in the loose pack bag, while the center of the bag generally heated more slowly, all three
temperature readings gradually converge, and the spores were all sterilized at all three locations.
However, there was not enough time for the bag in the dense pack configuration to reach a
sterilization temperature. Sterilization was only achieved between the first and second sheet.
Figure 4-12 presents the temperature profile within selected loose pack ceiling tile
bags. Similarly, the center of the bags heated slowest. However, all sample points came up to
temperature and all spores were sterilized in the loose pack arrangement.
4-4
-------
4.4 Temperature and Pressure
As mentioned previously, autoclave temperature and pressure are related
variables, as the autoclave is designed to operate at saturated steam conditions. Two conditions
were investigated: 31.5 psig/275°F, the typical operating pressure of the autoclave, and 45
psig/292°F, the maximum operating pressure of the autoclave. The effect of autoclave
temperature and pressure is best isolated from other variables by examining the data from Runs 1
and 8. Loose pack, wet and dry wallboard and ceiling tiles were processed in Run 1 at 31.5
psig/275°F and in Run 8 at 45 psig/292°F. Figure 4-13 compares the wallboard data collected
for Run 1 versus Run 8, and Figure 4-14 compares the ceiling tile data for both runs. For both
materials, the higher temperature and pressure accelerated the BDR heating process significantly.
However, all Bis from both runs exhibited no growth. Run 1 at the lower temperature was
conducted for 120 minutes while Run 8 at the higher temperature was terminated after 75
minutes.
4.5 Packing Orientation
Materials were tested both lying horizontally and positioned vertically. The
vertical packing arrangement was only tested in loose packing configuration using two 40-
minute autoclave cycles in sequence. The packing orientation variable is best isolated by
comparing wallboard and ceiling tile data between Runs 1 and 5 and carpet data between Runs 4
and 5. Figures 4-15 through 4-17, respectively, present the average data for these runs for each
item type. In reviewing these figures, only data for the first 40 minutes should be considered for
comparison purposes, as that is when the postvacuum cycle began during Run 5, which is
different from Runs 1 and 4. Accounting for the different starting temperatures between the
runs, the data appear variable and no firm conclusions can be drawn about the influence of
packing orientation on autoclave performance.
4-5
-------
4.6 Open Bags
Runs 5 and 6 were performed under the same conditions, except that two of the
eight bags tested were sliced open prior to autoclaving in Run 5 and all of the bags were sliced
open prior to autoclaving in Run 6. Figures 4-18, 4-19, and 4-20 present the average data from
these runs, comparing results for cut and uncut bags for wallboard, ceiling tiles, and carpet,
respectively. The data available to make this comparison are limited and somewhat variable. In
most cases, the data presented are for three sample locations within one bag of BDR. As seen on
Figure 4-18, wet wallboard in an uncut bag heated most rapidly. On Figure 4-19, ceiling tiles in
cut bags heated most rapidly. On Figure 4-20, dry carpet in an uncut bag heated most rapidly,
but wet carpet in an uncut bag heated most slowly. This uncut bag of wet carpet was the only
bag in Runs 5 or 6 to contain biological indicators with surviving spores. All other biological
indicators from these runs exhibited no surviving spores.
It is worth noting that even bags that were not cut open prior to autoclaving had a
tendency to rupture in the autoclave when subjected to the pressure differentials and heat of the
autoclave cycle.
Based on these data, we cannot draw any firm conclusions regarding the impact of
cutting bags open prior to autoclaving.
4.7 Two Sequential Cycles
As illustrated in Figures 3-5 and 3-6, conducting two standard autoclave cycles in
sequence proved to be quite effective in bringing BDR items up to the full autoclave temperature
rapidly after steam is applied during the second cycle. We believe that applying a vacuum
between the first and second cycles is what is particularly effective about this approach. The
first cycle acts to preheat the material, although it is likely that the initial contact between the
steam and the BDR material results in immediate condensation, filling pore spaces within the
material. Consequently, steam supplied later in the cycle does not penetrate well into the
material, and the material only slowly heats due to free convection and conduction from the bin
walls. Applying a vacuum prior to the second cycle likely pulls the condensate away from the
4-6
-------
material, and when steam is subsequently applied, it penetrates well into the material, which
quickly rises to the full autoclave temperature. In fact, Run 6 was terminated early because all
BDR materials had been over 270°F for 15 minutes well before the second cycle was scheduled
to be completed. When subjected to two autoclave cycles in sequence, all biological indicators
except for those in the one bag of wet carpet in Run 5 exhibited no surviving spores. Two
autoclave cycles did not consistently result in no-growth for BI test strips placed in wet carpet. It
may be necessary to further process wet carpet beyond two cycles to effectively sterilize it.
4-7
-------
310
oo
Run 2
Wallboard Dense Pack
45psig/292°F
20
40
60
80
100
120
140
Time (min)
•No Viable Spores Viable Spores Spore Viability Indeterminate
Figure 4-1. Run 2 Spore Viability
-------
310
Run 4
Carpet - Loose,
Dense, and Large Roll
31.5psig/275°F
20
40
100
60 80
Time (min)
•No Viable Spores Viable Spores Spore Viability Indeterminate
Figure 4-2. Run 4 Spore Viability
120
140
-------
Run 5
Multiple BDR Types
Vertical - Two Cycles
31.5psig/275°F
10
20
30
40
60
50
Time (min)
•No Viable Spores Viable Spores
70
80
90
100
Figure 4-3. Run 5 Spore Viability
-------
310
Dry Carpet (4 points)
Wet Wallboard (5 points)
Dry Wallboard (4 points)
Wet Ceiling Tiles (5 points)
Run 1
Multiple BDR Types
Loose Pack
31.5psig/275°F
Dry Ceiling Tiles (5 points)
50
20
40
60
Time (min)
80
100
120
Figure 4-4. Run 1 Moisture Content and Item Type Comparison
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
Sofa (4 points)
Wet Wallboard (5 points)
Dry Wallboard (5 points)
Dry Ceiling Tiles (5 points)
Wet Ceiling Tiles (5 points)
Run 8
Multiple BDR Types
Loose Pack
45psig/292°F
50
10
20
30
40 50
Time (min)
60
70
80
Figure 4-5. Run 8 Moisture Content and Item Type Comparison
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
90
-------
Dry Carpet (3 points)
Wet Wallboard (3 points)
—| Dry Wallboard (3 points)
Wet Carpet (3 points)
RunS
Multiple BDR Types
Vertical - Two Cycles
31.5psig/275°F
Wet Ceiling Tiles (3 points)
Dry Ceiling Tiles (3 points)
10
20
30
40
50
Time (min)
60
70
80
90
100
Figure 4-6. Run 5 Moisture Content and Item Type Comparison (Uncut Bags Only)
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
310
Wet Wallboard (3 points)
Dry Ceiling Tiles (6 points)
|Dry Wallboard (3 points)
Wet Ceiling Tiles (6 points)
Dry Carpet (3 points)
Run 6
Multiple BDR Types
Vertical - Two Cycles
All Bags Cut
31.5psig/275°F
Wet Carpet (3 points)
10
20
30
40
Time (min)
50
60
70
80
Figure 4-7. Run 6 Moisture Content and Item Type Comparison
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
310
290
270
250
230
Run 8 Dry Wallboard Loose Pack (5 points)
jRun 8 Wet Wallboard Loose Pack (5 points)
Run 2
Wallboard
Dense Pack
45psig/292°F
Run 2 Wet Wallboard Dense Pack (12 points)
Run 2 Dry Wallboard Dense Pack (12 points)
Run 8
Multiple BDR Types
Loose Pack
45psig/292°F
50
20
40
60 80
Time (min)
100
120
140
Figure 4-8. Wallboard Packing Density Comparison
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
310
Wet Carpet Loose Pack (4 points)
| Dry Carpet Loose Pack (4 points)
Wet Carpet Dense Pack (3 points)
Run 4
Carpet - Loose, Dense
and Large Roll
31.5psig/275°F
[LargeWet Carpet Roll (7 points)
Dry Carpet Dense Pack (4 points)
50
20
40
60 80
Time (min)
100
120
140
Figure 4-9. Carpet Packing Density Comparison
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
270
250
230
210
IWet Wallboard Bottom Layer (4 points)
| Dry Wallboard Bottom Layer (4 points) j^
Wet Wallboard Top Layer (4 points)
Wet Wallboard Middle Layer (4 points)
Dry Wallboard Top Layer (4 points)
Run 2
Wallboard
Dense Pack
45psig/292°F
Dry Wallboard Middle Layer (4 points)
20
40
60 80
Time (min)
100
120
140
Figure 4-10. Run 2 Dense Packing Layer Comparison
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
oo
270
250
230
210
190
g> 170
+-
re
0)
Q.
Run 1 Dry Wallboard Loose Pack
Between 4th and 5th sheet
Between 2nd and 3rd sheet
Between 1st and 2nd sheet
Between 4th and 5th sheet
Run 1
Multiple BDR Types
Loose Pack
31.5psig/275°F
Between 2nd and 3rd sheet
Between 1st and 2nd sheet
Run 2 Dry Wallboard Dense
Pack - Middle Layer
Run 2
Wallboard
Dense Pack
45psig/292°F
70
50
20
40
60
80
100
120
140
Time (min)
Figure 4-11. Comparison of Sample Points Within Selected Wallboard Bags
Note: 1st sheet was always on top in the bins.
-------
Run 5 Dry Vertical Ceiling Tiles
Between 7th and 8th sheet
Between 4th and 5th sheet
Between 2nd and 3rd sheet
Run 1
Multiple BDR Types
Loose Pack
31.5psig/275°F
Between 7th and 8th sheet
Between 4th and 5th sheet
Run 5
Multiple BDR Types
Vertical - Two Cycles
31.5psig/275°F
Between 2nd and 3rd sheet
Run 1 Dry Horizontal
Ceiling Tiles
50
20
40
60
Time (min)
80
100
120
Figure 4-12. Comparison of Sample Points within Selected Ceiling Tile Bags
Note: 1st sheet was always on top in the bins.
-------
to
o
290
270
250
230
210
190
0)
Q.
Run 8 - 292°F Wet Wallboard (5 points)
Run 8 - 292°F Dry Wallboard (5 points)
Run 1 - 275°F Wet Wallboard (5 points)
1 - 275°F Dry Wallboard (4 points)
Run 1
Multiple BDR Types
Loose Pack
31.5psig/275°F
Run 8
Multiple BDR Types
Loose Pack
45psig/292°F
0
20
40
80
100
60
Time (min)
Figure 4-13. Autoclave Temperature Comparison for Wallboard
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
120
-------
2QO
270
Run 8 - 292°F Dry Ceiling Tiles (5 points)
Run 1 - 275°F Dry Ceiling Tiles (5 points)
Run 8 - 292°F Wet Ceiling Tiles (5 points)
Run 1
Multiple BDR Types
Loose Pack
31.5psig/275°F
Run 1 - 275°F Wet Ceiling Tiles (5 points)
Run 8
Multiple BDR Types
Loose Pack
45psig/292°F
50
0
20
40
80
100
60
Time (min)
Figure 4-14. Autoclave Temperature Comparison for Ceiling Tiles
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
120
-------
to
to
Run 5 Wet Vertical Wallboard (3 points)
Run 1 Wet Horizontal Wallboard (5 points)
Run 1 Dry Horizontal Wallboard (4 points)
Run 1
Multiple BDR Types
Loose Pack
31.5psig/275°F
Run 5 Dry Vertical Wallboard (3 points)
RunS
Multiple BDR Types
Vertical - Two Cycles
31.5psig/275°F
0
20
40
80
100
60
Time (min)
Figure 4-15. Horizontal Versus Vertical Packing Orientation for Wallboard
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
120
-------
310
-^
to
2
0)
Run 5 Dry Vertical Ceiling Tiles
Uncut Bags Only (3 points)
Run 5 Wet Vertical Ceiling Tiles -
Uncut Bags Only (3 points)
Run 1 Dry Horizontal Ceiling Tiles (5 points)
Run 1
Multiple BDR Types
Loose Pack
31.5psig/275°F
Run 1 Wet Horizontal Ceiling Tiles (5 points)
RunS
Multiple BDR Types
Vertical - Two Cycles
31.5psig/275°F
20
40
80
100
60
Time (min)
Figure 4-16. Horizontal Versus Vertical Packing Orientation for Ceiling Tiles
120
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
-^
to
Run 5 Dry Vertical Carpet (3 points)
Run 4 Wet Horizontal Carpet (4 points)
Run 4
Carpet - Loose, Dense
and Large Roll
31.5psig/275°F
Run 4 Dry Horizontal Carpet (4 points)
Run 5
Multiple BDR Types
Vertical - Two Cycles
31.5psig/275°F
Run 5 Wet Vertical Carpet (3 points)
50
20
40
100
60 80
Time (min)
Figure 4-17. Horizontal Versus Vertical Packing Orientation for Carpet
120
140
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
to
310
290
Run 5 Wet Wallboard Uncut (3 points)
Run 6 Dry Wallboard Cut (3 points)
RunS
Multiple BDR Types
Vertical - Two Cycles
Wallboard Bags Uncut
31.5psig/275°F
Run 6 Wet Wallboard Cut (3 points)
Run 5 Dry Wallboard Uncut (3 points)
Run 6
Multiple BDR Types
Vertical - Two Cycles
All Bags Cut
31.5psig/275°F
50
10
20
30
40
60
70
50
Time (min)
Figure 4-18. Cut Versus Uncut Wallboard Bags
80
90
100
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
J^.
K>
310
290
270
250
130
110
50
Run 5 Wet Ceiling Tiles Cut (3 points)
Run 5 Dry Ceiling Tiles Cut (3 points)
Run 5 Dry Ceiling Tiles Uncut (3 points)
10
Run 5 Wet Ceiling Tiles Uncut (3 points)
RunS
Multiple BDR Types
Vertical - Two Cycles
Cut and Uncut Bags
31.5psig/275°F
20
30
40
60
70
50
Time (min)
Figure 4-19. Cut Versus Uncut Ceiling Tile Bags
80
90
100
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
Run 5 Dry Carpet Uncut (3 points)
Run 6 Dry Carpet Cut (3 points)
RunS
Multiple BDR Types
Vertical - Two Cycles
Carpet Bags Uncut
31.5psig/275°F
Run 5 Wet Carpet Uncut (3 points)
Run 6
Multiple BDR Types
Vertical - Two Cycles
All Bags Cut
31.5psig/275°F
Run 6 Wet Carpet Cut (3 points)
50
10
20
30
40
60
50
Time (min)
Figure 4-20. Cut Versus Uncut Carpet Bags
70
80
90
100
Each line on this graph is an average of multiple sample points. The number of sample points averaged is presented next to each series.
-------
s.o CONCLUSIONS
Based on variables evaluated in this study, the following conclusions can be
drawn regarding processing of BDR material in a commercial-scale autoclave. Conclusions
regarding sterilization are based on a finding of no growth, using 106 population BI test strips.
General Conclusions
• Achieving an internal BDR material temperature of 250°F or higher for 15
minutes or longer destroyed all biological indicators. The following approaches
were most effective in achieving this: using a loose packing configuration,
processing dry BDR material, establishing higher autoclave operating temperature
and pressure, and running multiple autoclave cycles in sequence.
• Bagged wallboard (wet or dry), ceiling tiles (wet or dry), and dry carpet can be
effectively sterilized under appropriate time, temperature, and packing conditions.
Time, temperature, and packing requirements are provided below.
• Dry upholstered furniture can be effectively sterilized. No conclusions are drawn
regarding wet upholstered furniture.
Time, Temperature, and Pressure Effects
• An autoclave cycle of 120 minutes at 31.5 psig/ 275°F effectively sterilized
wallboard, ceiling tiles, and dry carpet, when loaded in the autoclave as described
below.
• An autoclave cycle of 75 minutes at 45 psig/ 292°F effectively sterilized
wallboard and ceiling tiles, when loaded in the autoclave as described below.
• Two standard autoclave cycles of 40 minutes and 31.5 psig/ 275°F run in
sequence effectively sterilized wallboard, ceiling tiles, and dry carpet, when
loaded as described below. Available data suggest the second cycle can be
shortened to 20 minutes. Two autoclave cycles did not consistently result in no
growth for BI test strips placed in wet carpet. It may be necessary to further
process wet carpet beyond two cycles for effective sterilization. It appears that
evacuating the autoclave between the first the second cycle is critical, allowing
the second cycle to successfully sterilize the BDR.
Autoclave Loading
• Bags of BDR material should be placed in the autoclave so that all surfaces are
exposed to autoclave conditions. Bags lying flat against a metal surface, such as
the base of an autoclave bin, are considered to be fully exposed to autoclave
conditions.
5-1
-------
Bags of BDR material stacked or nested such that they are not fully exposed to
autoclave conditions may not be reliably sterilized under the conditions tested.
Bags of !/2 inch wallboard slabs up to 5 layers thick and 5/8 inch ceiling tiles up to
9 layers thick can be effectively sterilized under the time, temperature, and
packing density conditions described above.
Dry commercial grade carpet rolls formed from pieces 26 inches wide and 20 feet
long can effectively sterilized under the time, temperature, and packing density
conditions described above.
5-2
-------
6.0 REFERENCES
1. Quality Assurance Project Plan, Destruction of Spores on Building
Decontamination Residue in a Commercial Autoclave, prepared by Eastern
Research Group, Inc., Chantilly, VA, February 21, 2005.
2. "Work Plan, Waste Removal and Facility Cleaning, Department of State SA-32
Diplomatic Pouch and Mail Facility Sterling, VA." Submitted by U.S. Army
Corps of Engineers, Rapid Response Program and SE&I, Rev 3, November 12,
2002.
3. Boca, Pretorius, Gochin, Chapoullie, and Apostolides, 2002. "An Overview of
the Validation Approach for Moist Heat Sterilization, Part I." Pharmaceutical
Technology. September, 2002, pg. 62-70.
4. Barkley, W. and Richardson, 1, 1994. Laboratory Safety, pg. 715-734, in
Gerhardt, P., Murray, R., Wood, W., and Krieg, N. Methods for General and
Molecular Bacteriology, ASM. Washington, DC.
6-1
-------
Appendix A
PHOTOGRAPHIC LOG
-------
Photo 1. Healthcare Environmental's Oneonta,
New York Facility
Photo 3. Stacks of Size Reduced Wallboard and
Ceiling Tiles
Photo 2. Wallboard Size Reduction
Photo 4. Submersing Wallboard Sheets
Photo 5. Wallboard on Dry Rack
Photo 6. Assembled Sample Point
A-l
-------
Photo 7. Sample Point (Thermocouple Paired
with a BI Test Pouch)
Photo 9. Palletized Bags of Ceiling Tiles
Photo 8. Sample Point Between Sheets of
Drywall
Photo 10. Bulk Quantity of Used Commercial
Carpet
Photo 11. Carpet Wetting
Photo 12. Sample Point within Carpet
A-2
-------
Photo 13. Water Draining out of Assembled
Carpet Roll
Photo 14. Assembled Bags of Small Carpet Rolls
Photo 15. Assembled Large Carpet Rolls
Photo 16. Sofa Wrapping
Photo 17. Empty Autoclave
Photo 18. Empty Autoclave Bin
A-3
-------
.
Photo 19. Autoclave Bins on Transfer Cart
Photo 20. Bins Loaded into Autoclave
Photo 21. Flange Port
Photo 22. Fabricated Flange Port to Allow
Thermocouple Wires to Pass Through
Photo 23. Connectors Not Inverted Allowing
Condensate to Collect in the Connectors
Photo 24. Connectors Inverted to Allow
Condensate to Drip Off the Wires
A-4
-------
1
Photo 25. Data Acquisition System
Photo 26. Pallets of BDR Material
Photo 27. Loose Pack Wallboard Bin
Photo 28. Wallboard Bags After Autoclaving
Photo 29. Dense Pack Wallboard Bin
Photo 30. Loose Pack Ceiling Tile Bin
A-5
-------
Photo 31. Loose Pack Carpet Bin
Photo 33. Dense Pack Carpet Bin
Photo 32. Loose Pack Carpet Bin After
Autoclaving
Photo 34. Large Carpet Roll on Pallet for
Autoclaving
Photo 35. Vertical Orientation
Photo 36. Vertical Packaging Orientation After
Autoclaving
A-6
-------
Photo 37. Full Exposure Control Sample
Photo 38. Stringing Thermocouple Wires Along
the Top of the Bins
Photo 39. Connecting Thermocouple Wires
Photo 40. Removing BI Test Pouches From Sofa
Photo 41. Removing BI Test Pouches from BDR
Photo 42. BI Test Pouches Packed for Shipment
to Laboratory
A-7
-------
&EPA
United States
Environmental Protection
Agency
Office of Research and Development
National Homeland Security Research Center
Cincinnati. OH 45268
Official Business
Penalty for Private Use
$300
EPA/600/R-05/081
April 2005
PRESORTED STANDARD
POSTAGE & FEES PAID
EPA
PERMIT NO. G-35
Recycled/Recyclable
Printed with vegetable-based ink on
paper lhat contains a minimum of
50% post-consumer fiber content
processed chlorine free
------- |