EPA/600/B-18/229 I August 2018
www.epa.gov/homeland-security-research
United States
Environmental Protection
Agency
&EPA
Evaluation of Liquid-, Foam-,
and Gel-Based Decontaminants
Office of Research and Development
Homeland Security Research Program
-------
EPA/600/R-18/229
August 2018
Evaluation of Liquid-, Foam-
and Gel-Based Decontaminants
by
Vipin Rastogi and Savannah Hurst
U.S. ARMY Edgewood Chemical Biological Center
Aberdeen Proving Ground, Aberdeen, MD
Interagency Agreement #DW021 924504-01
and
M. Worth Calfee
U.S. Environmental Protection Agency, Office of Research and
Development, National Homeland Security Research Center
Research Triangle Park, NC 2771 1
-------
Acknowledgments
The principal investigator from the U.S. Environmental Protection Agency (EPA), through its
Office of Research and Development's National Homeland Security Research Center (NHSRC),
directed this effort with the support of a project team from across EPA. The contributions of the
individuals listed below have been a valued asset throughout this effort.
Project Team
M. Worth Calfee, EPA, ORD/NHSRC/DCMD
Vipin Rastogi, US ARMY ECBC
Elise Jakabhazy, EPA, OLEM/CMAD
Leroy Mickelsen, EPA, OLEM/CMAD
Rich Rupert, EPA, Region 3
Shannon Serre, EPA, OLEM/CMAD
Savannah Hurst, EXCET, INC.
EPA Quality Assurance
Eletha Brady-Roberts, EPA, NHSRC/DCMD
Peer Reviewers
Joseph Wood, EPA, NHSRC/DCMD
Christopher Gallo, EPA, OLEM, ERT
-------
Notice/Disclaimer Statement
The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development's
(ORD's) National Homeland Security Research Center (NHSRC), funded, directed and managed this
work through an Interagency Agreement (DW021924504-01) with the U.S. Army Edgewood Chemical
Biological Center (ECBC). This report has been peer and administratively reviewed and has been
approved for publication as an EPA document. The views expressed in this report are those of the authors
and do not necessarily reflect the views or policies of the Agency. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use of a specific product.
Questions concerning this document or its application should be addressed to:
M. Worth Calfee, Ph.D.
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Mail Code E343-06
Research Triangle Park, NC 27711
919-541-7600
iv
-------
Table of Contents
Acknowledgments iii
Notice/Disclaimer Statement iv
Executive Summary 1
1.0 Project Background 2
1.1 Project Purpose 2
1.2 Process 2
2.0 Materials and Methods 3
2.1 Literature Review for Selection of a Foam / Gel Generating Device 3
2.2 Test Panel Procurement 3
2.3 General Testing Approach 4
2.4 Phase One: Small Scale Decontamination Application Variables 5
2.5 Phase Two: Chamber Decontamination Testing 8
2.6 Panel Inoculation 10
2.7 Decontamination Agents 11
2.7.1 pAB Solution 11
2.7.2 Spor-Klenz® Ready-to-Use (RTU) Solution 11
V
-------
2.8 Sampling Strategy 12
2.8.1 Wipe Sampling 12
2.9 Runoff Analysis 12
2.10 Aerosol Sampling 13
2.11 Microbial Analysis 13
3.0 Quality Assurance/Quality Control (QA/QC) 15
3.1 Data Quality Objectives 15
3.2 Data Quality Indicators 15
4.0 Results 18
4.1 Literature Review-based Selection of Dispensing Units 18
4.1.1 Selection of a Foam ing Agent 20
4.2 Phase One: Small Scale Decontamination Application Variables 23
4.3 Testing Issues and Observations 38
4.4 Phase Two: Chamber Decontamination Testing 38
4.4.1 Comparative Sporicidal Efficacy of pAB and Spor-Klenz Applied as Liquid
vs. Foam 38
4.4.2 Spore Recovery from Control panels 38
4.4.3 Spore Recovery from Control Panels by Wipes and Spore
Reaerosolization Analysis 39
4.4.4 Decontamination Efficacy 40
vi
-------
5.0 Conclusions and Future Recommendations 42
6.0 Literature Cited 47
7.0 Appendices 48
Appendix A: Parameter Studies- 90°F Full Picture Assembly 48
Appendix B: Parameter Studies- 50°F Full Picture Assembly 49
vii
-------
Figures
Figure 2-1: Aerosol Deposition Chamber in Building E-5951 5
Figure 2-2: Experimental and Control Samples for Phase Two 8
Figure 2-3: Experimental Scheme for Decontamination Testing 9
Figure 2-4: Phase Two, Typical Single Test Run 10
Figure 2-5: Panel Holder Unit for Spray and Run-off Collection 13
Figure 4-1: Effect of Phos-Chek on Spor-Klenz efficacy (10-minute exposure), using Bacillus
atrophaeus spores on glass 22
Figure 4-2: Effect of Phos-Chek on pH-adjusted Bleach efficacy (10-minute exposure), using
B. atrophaeus spores on glass 22
Figure 4-3 (A-H): Wetness value profile under four ambient conditions with fan on/off 25
Figure 4-4: 90°F Picture Assembly 30
Figure 4-5: 50 °F Picture Assembly 34
Figure 4-6: Spore Recovery and Partitioning from Control Panels 39
Figure 4-7: Spore Recovery with Wipes and Reaerosolization Analysis 40
Figure 4-8 Comparative Decontamination Efficacy of pAB and Spor-Klenz RTU (SK) Applied
as Liquid or Foam 41
viii
-------
Tables
Table 2-1: Building materials for sampling sequence 4
Table 2-2: Stage one test matrix 6
Table 2-3: Test matrix for Phase 2 testing with large panels. Each test included one
disinfectant and one operating test condition 9
Table 3-1. DQIs for the Critical Measurements and Data Completeness Criteria 16
Table 3-2. Additional Data Quality Indicators Specific to Microbiological Data 17
Table 4-1: Foam Applicator Summary 19
Table 4-2: Gel Applicator Summary 20
Table 4-3: Foaming Additive Summary 21
Table 4-4: Summary of Study Test Run Logs for Phase One Physical Parameters, Steel and
Concrete Surfaces 24
Table 4-5: Steel Picture Analysis 29
Table 5-1: Spore removal, surface reduction and decontamination efficacy for Spor-Klenz (A)
and pAB application (B) at 90 °F and 25% RH 44
Table 5-2: Spore removal, surface reduction and decontamination efficacy for Spor-Klenz (A)
and pAB application (B) at 50 °F and 70% RH 45
Table 5-3: Paired t-test Results 46
ix
-------
Acronyms and Abbreviations
AOAC AOAC International
ATCC American Type Culture Collection
BSL Bio-Safety Level
BW Biological Warfare
CBR Chemical, Biological, Radiological
CBRN CMAD The Chemical, Biological, Radiological and Nuclear Consequence
Management Advisory Division
CD Chlorine Dioxide
CFU Colony Forming Unit(s)
COC Chain of Custody
DAC Digital-to-Analog Converter
DCMD Decontamination and Consequence Management Division
DHS Department of Homeland Security
DI Deionized
DPG Dugway Proving Grounds
DQI Data Quality Indicator
DQO Data Quality Objective
ECBC Edgewood Chemical and Biological Center
EPA U.S. Environmental Protection Agency
ERT Environmental Response Team (EPA)
FIFRA Federal Insecticide, Fungicide, and Rodenticide Act
FAC Free available chlorine
ft Foot
GPM Gallons per Minute
H2O2 Hydrogen peroxide
HEPA High-Efficiency Particulate Arrestance
Hr Hour(s)
HS Heat Sensitivity
HSPD Homeland Security Presidential Directive
ID Identification
L Liter
lpm Liters per Minute
x
-------
m Cubic Meter(s)
ma Milliampere
mg Milligram(s)
min Minute(s)
ml Milliliter(s)
mm Millimeter(s)
MDI Metered-Dose Inhaler
MOP Miscellaneous Operating Procedure
NHSRC National Homeland Security Research Center
OLEM Office of Land and Emergency Management
OPP Office of Pesticide Programs
ORD Office of Research and Development
PAA Peracetic Acid
pAB pH-adjusted Bleach
PAPRs Powered Air Purifying Respirators
PARTNER Program to Align Research and Technology with the Needs of Environmental
Response
PBST Phosphate-buffered Saline with Tween 20
PI Principal Investigator
PPE Personal Protective Equipment
ppm Parts Per Million
ppmv Parts Per Million by Volume
psi Pounds Per Square Inch
QA Quality Assurance
QAO Quality Assurance Officer
QAPP Quality Assurance Proj ect Plan
QC Quality Control
RH Relative Humidity
RFU Reference Filter Units
RSD Relative Standard Deviation
RTU Ready-to-Use
SD Standard Deviation
S-K Spor-Klenz
SOP Standard Operating Procedure
xi
-------
STS
Sodium Thiosulphate
TSA
Tryptic Soy Agar
USG
United States Government
VHP
Vaporous Hydrogen Peroxide
WA
Work Assignment
xii
-------
Executive Summary
For fixed-site surface decontamination and cleanup, two distinct options among liquid disinfectants
include pH-adjusted bleach (pAB) and Spor-Klenz® (S-K; per-acetic/peroxide formulations). Efficacy of
these two sterilants in lab-scale studies has been well-documented. In a recent study completed by a multi-
agency group led by EPA, pAB was found to be effective; however, some collateral damage was evident
(EPA/600/S-15/001). In different studies throughout recent years, disinfectants have been applied as
liquids, foams, or gels. While no information is currently available on comparative effectiveness of foam
or gel over liquids, it is often hypothesized that foam- or gel-based decontaminants will be more effective
because of prolonged wetted contact times. Scientific data supporting this hypothesis is lacking. The
objective of this effort was to compare three delivery methods (i.e., liquids, foam and gel) of liquid
disinfectants on concrete and steel in vertical orientation. Two decontaminants, Spor-Klenz® and pAB
(representing two distinct chemistries) were selected for this study. Environmental conditions were varied
to include: 50 °F/70% RH and 90 °F/25% RH, with fan ON or OFF to simulate wind velocity. Runoff was
collected to assess mechanical dislodgment vs. sporicidal efficacy, and panels were wipe-sampled
following the 30 minute contact time to estimate the amount of viable spores remaining.
As for controls, water was applied instead of disinfectant for each method of application. Runoff was
collected, and panels were wipe-sampled, to determine the total number of spores capable of being
recovered. Additional panels were simply wiped down to determine the inoculation density for each test
run. Procedural blanks and air filter controls were also included throughout the experimental study to
monitor possible sources of contamination.
Unfortunately, the gel application was discontinued midway through the work because of issues related
to its application after re-formulation. The gel, as provided by the vendor, was not of the proper
consistency (not viscous enough) once amended with decontaminant (10% volume amendment). A
modified gel was requested from the manufacturer. The modified gel was requested to be of proper
viscosity after amended with 10% decontaminant volume. A suitable gel was unable to be procured from
the vendor, forcing discontinuation.
Overall, the results of this study show that vertically-oriented surfaces are difficult to decontaminate with
just one application of a sporicidal chemical, regardless of decontaminant formulation (liquid or foam).
Direct observation tests showed that foam application maintained surface wetness longer than liquid.
However, no significant difference in efficacy in terms of log reduction with the use of foam was observed
relative to liquid application.
l
-------
1.0Project Background
1.1 Project Purpose
The purpose of this project was to compare sporicidal decontaminants applied as liquid, foam, or
as a gel for decontaminating indoor and outdoor building materials contaminated with Bacillus spores.
Using the same dispenser, sporicidal chemicals could be applied as liquid or as foam after mixing with a
foaming surfactant. Addition of foaming agent reduces the surface tension of water (liquid), and when
mixed with air generates a foam blanket, which may adhere to vertical and inverted surfaces longer than
liquids, thereby increasing wetted contact times and potentially increasing decontamination efficacy.
Alternatively, sporicidal chemicals can be mixed with gel and applied as viscous suspension, which dries
into a thin film. In this third type of sporicidal application, it is also assumed that the contact time between
the chemical and surface contaminant is significantly increased. Key factors, such as wetting duration,
volume of liquid applied, sporicidal efficacy, visual damage to materials, and ease of use (including clean
up after application) were evaluated under lab-scale tests. A survey of currently- and commercially-
available methods for generating foam or gels from liquids was conducted. Following identification of the
generation methods, and selection of the preferred method for testing, decontamination tests were
conducted with pH-adjusted bleach, and Spor-Klenz®. Decontamination efficacy, on surfaces
contaminated with Bacillus spores, was determined for foam- or gel- and liquid-based decontaminants, in
a side-by-side manner. Various material types were tested under the two environmental conditions (50
°F/70% RH and 90 °F/25% RH). The damage to materials during decontamination procedures was visually
monitored.
1.2 Process
The general approach that was used to meet the objectives of this project is outlined as follows:
1. Market survey to determine currently commercially available liquid, foam and gel generation
systems, including equipment for spray-based application to surfaces;
2. Compare response variables when the same sporicidal decontaminants are applied as liquid,
gel or foam;
3. Inoculation of the test materials with Bacillus atrophaeus (formerly, B. globigii) spores via
aerosol deposition;
4. Spray application of foam, gel, or liquid decontaminants onto the surfaces of the contaminated
materials;
5. Assessment of residual viable spores (via post-decontamination sampling), starting inoculation
(via sampling of positive controls), and potential cross-contamination (via sampling of
negative controls (blanks));
6. Analysis of subsequent impacts to materials;
7. Determination of decontamination effectiveness as measured by log reduction from the test
samples compared to positive control samples; and
8. Documentation of operational considerations (e.g., cross-contamination, procedural time,
impacts on materials and personnel).
2
-------
2.0 Materials and Methods
This project was comprised of three tasks:
1. Conduct a search for readily-available sporicidal liquids, foams, and gels, as well as foam and gel
generation methods and devices that are compatible with the application (spray-based
decontamination of indoor and outdoor surfaces) and liquids (bleach, hydrogen peroxide,
peroxyacetic acid, etc.) intended for use during expedient indoor or outdoor decontamination
operations.
2. Evaluate the response variables (wetted contact time and volume dispensed) under various
environmental test conditions (air velocity, relative humidity, and temperature) when sporicidal
decontaminants were applied as liquid, gel, or foam.
3. Determine decontamination efficacy of liquid, foams, or gel decontaminants under various
conditions with test panels. Each decontamination formulation (pAB or Spor-Klenz) was to be
prepared as a liquid, gel, and/or foam, and the efficacy of each form then compared to determine
the advantage (or lack thereof) of each.
2.1 Literature Review for Selection of a Foam / Gel Generating Device
An extensive review of commercially-available, foam and gel generating devices was conducted.
Products were evaluated based on price, availability, usability, intended uses, and compatibility with the
decontaminants in question. The summary of this literature review is summarized in the Results section.
While it was desired that the same unit be able to apply all three technologies, such was not the case. Due
to the high viscosity of the gel, the 5-gallon Foam-it unit selected was unable to dispense gel properly,
leading to an airless paint sprayer to be used instead. Use of the Foam-it unit was continued for liquid and
foam technologies. A different nozzle was required to operate the unit for each technology as well as the
addition of a foaming agent to produce foam.
While a review of foam and gel generating devices was conducted, commercially-available
decontamination gels and foams were also reviewed along with foaming agents (additives to generate
foam from a liquid). In order for a disinfectant to be sprayed as foam, a foaming agent (which may or may
not be a detergent) must be included. A review of foaming additives and studies related to final selection
is summarized in the Results section.
2.2 Test Panel Procurement
The representativeness and uniformity of test materials was essential in achieving defensible
evaluation results. Material representativeness means that these materials are typical of those currently
used in buildings in terms of quality, surface characteristics, and structural integrity. In this effort,
representativeness was assured by selecting test materials that met industry standards or specifications for
use, and by obtaining those materials from appropriate suppliers. Material uniformity means that all these
material panels are equivalent for purposes related to testing. Uniformity was maintained by obtaining and
preparing a quantity of material sufficient to allow multiple test samples to be prepared with presumably
uniform characteristics (i.e., test panels will be cut from the interior rather than the edge of a large piece
of material). Two building materials (concrete and steel) were used in this study. Specifications of test
panel materials and material preparation instructions are given in Table 2-1.
3
-------
Table 2-1: Building materials for sampling sequence
Material
Description
Manufacturer/
Supplier
Name
(location)
Inoculated
Surface Size,
L x W (inches)
Phase 2
Material Preparation and
Sterilization
Concrete
Finished
Concrete, 1 inch
thick
American
Custom Concrete
Edgewood, MD
12 xl2 inch
Washed in distilled water and
sprayed with 70% ethanol then
treated with UV light in
biosafety cabinet for 1 lir.
Black Steel
A3 6 14 ga„
deburred edges
Phoenix Metals,
Baltimore, MD
12 x 12 inch
Sprayed with 70% ethanol
between test runs then
autoclaved for 30 minutes prior
to disposal
Due to the weight constraints of concrete and the corrosivity of steel, panels were not autoclaved to
sterilize prior to testing but rather were disinfected with 70% ethanol. Coupons were autoclave-sterilized
before disposal. Upon receipt, panels were placed in a sterile container for storage and transported to the
testing location. The container was marked with the contents, including production information provided
by the manufacturer. The sterility of the panels was verified through the use of lab blank control samples.
2.3 General Testing Approach
Prior to any decontamination testing involving material panels, foam and gel generation was
optimized for the chosen disinfectants; pH-adjusted bleach and Spor-Klenz®. Optimization was not needed
for liquid generation as these disinfectants are readily deployed in a liquid state. Our initial goal was to
use one single dispenser for applying sporicidal chemical as liquid, foam, or gel. 'Foam-it' was selected
for applying two versions of the disinfectant, i.e., liquid and foam (both required different nozzles and
pressure settings for ainliquid mix). Based on preliminary testing, the gel could be delivered using the
same dispenser (primarily because of the gel viscosity).
Decontamination testing was conducted in two phases. In the first phase, various response variables
(percent wetness, duration of wetness) were tested on vertical 12 x 12 inch panels for all three modes of
application with water as a surrogate for the disinfectants. Two material types were used for this phase
(concrete and steel).
The results from the first phase of testing were used in the second phase to down-select control variables
and parameters for more rigorous, mid-scale spray chamber decontamination testing (phase 2). Concrete
and steel panels were inoculated through aerosol deposition and placed in the chamber in the same
orientation (vertical). For each given decontaminant, the method of application was applied side by side,
and the resultant efficacy of each method was compared by surface sampling and analysis and generation
of log-reduction data based on recovery from positive control panels. Efficacy was determined as log
reduction in number of viable spores, which was calculated as follows: log reduction = log (spores from
control panels) - log (spores from test panels).
All testing was conducted in the aerosol deposition chamber located in building E-5951 of ECBC (Figure
2-1) to accommodate for the different test variables. The aerosol deposition chamber is a 64 cubic meter
(m3) biosafety level-l+ (BSL-1+) chamber. Temperature and relative humidity (RH) of the chamber were
maintained at the required test conditions. High-Efficiency Particulate Arrestance (HEPA) filters were
4
-------
installed at the inlet to filter air entering the chamber to achieve very low background particle
concentrations in the chamber. Similarly, HE PA filters were installed at the exhaust port to filter all
particles exiting the chamber. The internal chamber wind speed was determined with the Kestrel 3000
pocket weather meter. The wind speed was determined by taking the average velocity for a minute
duration at 1 meter from the front surface of the center tile. The Kestrel is a high precision impeller-based
vaneometer; its description can be found at: https://www.extrememeters.eom/products/kestrel-3000-
pocket-weather-meter.
Temperature and RH readings were monitored by an Alta labs heat sensitivity (HS) series combination
temperature and humidity duct mount sensor. The 4 -20 milliampere (ma) outputs are proportional to the
real-time readings of temperature and RH, which feed into the control computer digital-to-analog
converter (DAC) board. An in-house software control system based on Lab VIEW controls a humidifier,
refrigeration units and heaters to achieve the desired set parameter conditions. The control computer
monitors the sensor readings 10 times/sec and utilizes a feedback loop to constantly adjust the temperature
and RH to within 5% of the desired settings. However, these parameters can be difficult to maintain at the
required levels due to the aerosolization of the decon agent during testing. These variables can create long
delays before conditions are stabilized. Additionally, evacuation of the chamber to remove test particles
after a release causes changes in temperature and RH, creating additional equilibration periods for the
conditions to re-establish to set values.
Figure 2-1: Aerosol Deposition Chamber in Building E-5951
2.4 Phase One: Small Scale Decontamination Application Variables
Liquid, foam and gel application were applied to the steel and concrete panels using water as a
control for the disinfectants. Based on our review of the current dispensing applicators, two separate units
had to be down-selected—one for dispensing liquid and foam and the other for dispensing viscous gel.
For the first one, 'Foam-it" was selected. Even though claims were made by the manufacturer for
application of "Foam-it" as a gel dispenser, lack of adequate pressure (<60-psi) precluded gel from being
5
-------
dispensed. The 5-gallon air operated portable foam equipment was used in accordance with procedures
outlined in the user manual provided by the manufacturer. To summarize, the unit was attached to an
airline at the air fitting with the ball valve remaining in the closed position. The ball valve was then slowly
opened, and the needled valve was adjusted based on desired wetness or dryness of the foam by opening
it in a counter-clockwise direction at Vi turn increments every 30 seconds. Coupons (small representative
and uniform pieces of the test materials) were sprayed in a back-and-forth manner until the coupon surface
was covered completely with foam. After operations were completed, the unit was flushed with fresh
water for 5 minutes and disconnected from the air fitting. Pressure was relieving by opening the discharge
valve. All pressure was relieved before the ball valve was closed and the unit was stored until further use.
An attempt was made to dispense gel using the same 'Foam-it' unit, but due to high viscosity of the gel,
the gel could not be sprayed. Therefore, an airless sprayer was selected for gel (see Results section).
During testing, the airless paint sprayer was operated in accordance with the operation manual provided
by the manufacturer. In short, the unit was primed prior to start up and then powered on at the lowest
pressure. Pressure was increased every 15 seconds until the desired output was achieved. Once the gel
output was acceptable, coupons were sprayed in a back-and-forth manner until the coupons were
completely covered with an adequate layer of gel. After operation, the unit was thoroughly flushed to
prevent clogging.
Dependent and independent variables were assessed during spray application tests such that the results of
this round of testing dictated the mid-scale testing parameters. The independent variables included air
velocity, relative humidity and temperature. Wind velocity was tested with and without a fan (one fixed
setting), with a velocity of 0.8-1.0 m/s during fan usage. Two temperatures were tested: 50°F (10°C) and
90°F (32°C), as well as two relative humidity levels: 25 +/- 10% and 70 +/- 10 % as outlined in Table 2-
2.
Table 2-2: Stage one test matrix
Test Identification
(ID)
Application
Wind
Temp
Relative
Humidity
1 and 2
liquid
none
50 °F
25%
3 and 4
foam
none
50 °F
25%
5 and 6
gel
none
50 °F
25%
7 and 8
liquid
yes
50 °F
25%
9 and 10
Foam
yes
50 °F
25%
11 and 12
Gel
yes
50 °F
25%
13 and 14
liquid
none
50 °F
70%
15 and 16
Foam
none
50 °F
70%
17 and 18
Gel
none
50 °F
70%
19 and 20
liquid
yes
50 °F
70%
6
-------
21 and 22
Foam
yes
50 °F
70%
23 and 24
Gel
yes
50 °F
70%
25 and 26
Liquid
None
vo
O
O
T!
25%
27 and 28
Foam
None
vo
o
o
T!
25%
29 and 30
Gel
None
vo
o
o
T!
25%
31 and 32
Liquid
Yes
vo
o
o
T!
25%
33 and 33
Foam
Yes
vo
o
o
T!
25%
34 and 35
Gel
Yes
vo
o
o
T!
25%
36 and 37
Liquid
None
vo
o
o
T!
70%
38 and 39
Foam
None
vo
o
o
T!
70%
40 and 41
Gel
None
vo
o
o
T!
70%
42 and 43
Liquid
Yes
vo
o
o
T!
70%
44 and 45
Foam
Yes
vo
o
o
T!
70%
46 and 47
Gel
Yes
vo
o
o
T!
70%
* These tests were conducted with water as a simulant for the two sporicides. All even numbers were
concrete panels and all odd numbers were steel panels.
The response (dependent) variables analyzed were volume of sporicide dispensed and wetted surface
contact time. For concrete panels, wetted surface contact time was measured by the Hygrometer
Dampmaster (Model # 082.020A), manufactured by PCE Americas (Jupiter, FL). The hygrometer could
not be used on steel panels (which have a conducting surface) due to the mechanism in which it measures
moisture by way of electric resistance. It is not intended for use on metals and therefore only qualitative
measurements could be taken in the form of visual observations documented through pictures (Figures 3.5
and 3.6).
Liquid, foam and gel application were applied to the steel and concrete panels using water as a control for
the disinfectants. In a typical run, the volume dispensed ranged from 300-375 ml. The spraying was done
long enough to ensure full wet coverage of the surface. The dispensing rate was 50-75 ml per minute and
the spraying time ranged from 6-8 min in total. Each was applied to the test coupons using a standardized
procedure, designed to obtain a completely wetted surface for each material type. Test and response
variables were assessed such that the results of this round of testing dictated the mid-scale testing
parameters. The test conditions included variable wind velocity, relative humidity and temperature. Air
velocity was tested with and without a fan (one fixed setting). Two temperatures were tested: 50 °F (10°C)
and 90 °F (32°C), as well as two relative humidity levels: 25 +/- 10% and 70 +/- 10 %. All experimental
conditions for the evaluation of physical parameters were completed over a series of eight runs,
summarized in the Results section.
7
-------
2.5 Phase Two: Chamber Decontamination Testing
In the second phase, decontamination effectiveness of foam versus liquid sporicide application
was tested over a series of test conditions (independent variables). The gel was not included due to its
inability to be sprayed after re-formulation with sporicidal chemical. Viscosity alteration precluded the
gel from being sprayed using a commercial airless Graco sprayer. The general experimental approach
used to meet the objectives of this phase are shown in Figures 2-2, 2-3, and 2-4, and were as follows:
• A known quantity of surrogate organisms [1-5 x 107 colony forming units (CFU) of B.
atrophaeus spores] was deposited on concrete and steel panels (12 x 12 inch).
• Panels were treated with decontamination agents in liquid and foam form, and the sporicidal
effectiveness (decontamination efficacy) was evaluated by measuring the difference in the
logarithm of the measured contamination before decontamination (determined by sampling
positive control panels) and after decontamination (determined by sampling the test panels
after treatment). The number of viable organisms was determined as colony forming units
(CFUs). Decontamination efficacy is reported as log reduction.
• Spore relocation to aerosol and liquid waste were assessed by analysis of process effluents
(run-off) and air samples collected during the decontamination process. These have
important implications regarding aerosol risks and/or ground contamination resulting in
downstream health risks.
• Post-decontamination, physical impacts on materials were determined through visual
inspections and were documented in laboratory notebooks and by digital photographs.
The experimental scheme for phase 2 testing can be summarized in the following figures:
Figure 2-2: Experimental and Control Samples for Phase Two
Three positive panels
~
~ 1
~
Three Test panels
~
~
~
One procedural negative control
~
Positive panels can be defined as those that have been inoculated but were not exposed to
decontamination treatment. Test panels were inoculated and exposed to the test decontamination
treatment. The procedural negative control was neither inoculated nor subjected to decontamination
treatment.
8
-------
Figure 2-3: Experimental Scheme for Decontamination Testing
Panel
Cleaning
Spore
Loading
Panel
Fabrication
Microbiological
Analysis
Collection of Aerosol
Overnight Settling
Panels Surface Sampling
Decontamination with Liquid and
Foam or Liquid
Table 2-3: Test matrix for Phase 2 testing with large panels. Each test included one disinfectant
and one operating test condition
Test Run
#
Decon Tech.
Applied As:
Material
Types
Orientation
Test Variable
Combinations
Response
Variable
1 and 2
Liquid
concrete
vertical
50 °F and 70%
90 °F and 25%
Decon efficacy
3 and 4
Foam
concrete
vertical
50 °F and 70%
90 °F and 25%
Decon efficacy
1* and 2*
Liquid
steel
vertical
50 °F and 70%
90 °F and 25%
Decon efficacy
3* and 4*
Foam
steel
vertical
50 °F and 70%
90 °F and 25%
Decon efficacy
Each test run included three test panels, three sprayed control panels, one wiped control panel for each
applicator type (seven in total), and one procedural blank panel per run; therefore, a total of 15 panels of
each material was utilized for ONE decontaminant and ONE Operating Test Condition.
9
-------
Figure 2-4: Phase Two, Typical Single Test Run
TESTS
CONTROLS
~ ~~
~ ~~
~
Liquid
Sprayed (+)
Wipe (+)
~ ~~
~ ~~
~
Foam
Sprayed (+)
Wipe (+)
~
Procedural Blank (-)
2.6 Panel Inoculation
Panels (test and positive controls) were placed on the floor of the aerosol deposition chamber. The
fluidized spores were aerosolized onto the concrete and steel panels using a two-fluid pneumatic high-
flow sonic nozzle. A brief description of this nozzle follows. The fluidized milled B. globigii spore
preparation used for this project was procured from Dugway Proving Grounds. A specifications sheet with
certificate of analysis documented QA/QC of the spore preparation upon receipt. Spores were prepared
by milling the preparation until particles consisted of single spores and then adding fluidizer. The fluidized
spores (-100 mg by weight) were aerosolized using a two-fluid pneumatic sonic nozzle (SRI International,
Menlo Park, CA). A brief description of this nozzle follows. One nozzle was connected to the compressed
air that exits through a small annular opening; the other was connected to the powder to be aerosolized.
The low pressure created in the exit region due to the air flow causes powder to be pulled through an axial
tube at a very low feed rate due to the Bernoulli Effect. The desired air-to-powder mass ratio was 80-
100:1. Powder was fed into the nozzle through a 1/4 -inch (internal diameter) stainless tube. The nozzle
air pressure can be varied, thereby varying the dispersing airflow rate. The compressed air (800-1,300-
L/min) was passed through a 3/8-inch (outer diameter) by 5/16-inch (internal diameter) orifice. The nozzle
aspirated air into the feed tube, although air was normally supplied to the tube from a powder feeder.
Measurements showed that at a flow rate of 1,300-L/min, the disperser produced a vacuum of 12.5 cm
Hg.
The procedure described above was used to generate aerosols inside the chamber. The aerodynamic
particle size (0.5-10 microns, based on previous studies) was expected to be in the range of 1-10 microns,
but was not determined in the current study. The chamber air was mixed by fans after and/or during the
aerosol generation to achieve a uniform aerosol concentration in the chamber. Previous tests showed that
mixing the aerosol in the chamber for 1 min was adequate to achieve a uniform aerosol deposition. After
the aerosol deposition process, fans were turned off and the spores were allowed to settle overnight. The
following day, prior to sample collection, all chamber floor surfaces were wiped down with pAB to
minimize the spore movement from the floors to the test panels.
10
-------
The aerosol chamber was cleaned between runs by exhausting the chamber air through the HEPA filters,
and by pumping HEPA-filtered air into the chamber. The maximum amount of airflow exhausted from
the chamber by the exhaust pump was approximately 2 x 104 liters per minute (1pm). There was also a
small recirculation system that removed air from the chamber, passed it through a HEPA filter, and
delivered it back to the chamber. This system was useful when the aerosol concentration in the chamber
needed to be reduced incrementally. In addition, the chamber walls and floor were wiped down with 10%
bleach between runs.
2.7 Decontamination Agents
Decontamination, in the context of this study, is the combination of physical and chemical
processes that kills or removes pathogenic microorganisms. There are several groups of standard
disinfectants that are effective against a broad range of viruses and bacteria: soaps and detergents,
oxidizing agents, alkalis, acids, and aldehydes. This study focused on the following oxidizing chemicals
commonly used as disinfectants: sodium hypochlorite/hypochlorous acid (pH-adjusted bleach (pAB)) and
hydrogen peroxide/peroxyacetic acid (Spor-Klenz®).
2.7.1 pAB Solution
Sodium hypochlorite (bleach) is a registered antimicrobial pesticide under the authority of FIFRA
for use as a sanitizer or disinfectant to kill bacteria, fungi, and viruses in households, food processing
plants, agricultural settings, animal facilities, hospitals, and human drinking water supplies. However,
bleach is not a registered sterilant under FIFRA and does not have a registration claim to inactivate
Bacillus spores, although some associated products containing sodium hypochlorite have made claims
regarding spores of Clostridium difficile. Published scientific data demonstrated that pAB reduced
bacterial spore populations under specific conditions including concentration, pH, and contact time.
Hence, EPA issued several crisis exemptions at different times permitting the limited sale, distribution,
and use of bleach products against B. anthracis spores at a number of contaminated facilities (Canter,
2005): Capitol Hill, the U.S. Postal Service Processing and Distribution Centers at Brentwood
(Washington, D.C.) and Hamilton (Trenton, NJ), the Department of State, the General Services
Administration, and Broken Sound Boulevard, Boca Raton, FL.
With respect to the current study, bleach (Clorox germicidal, EPA reg. no. 67619-8, lot no.
E616351) solution was prepared (just an hour before use) by first mixing one-part bleach (5.25-6.25%)
with one-part 5% acetic acid and eight-parts water. The diluted solution was close to pH 7, as verified by
pH meter. The free available chlorine was confirmed to be 5,000 - 6,000 parts per million (ppm). The
concentration of household bleach and the strength of acetic acid can vary by batch and storage time.
Hence, following the above mixing directions can result in varied pH and chlorine concentrations
depending upon the starting reagents. This source of variation can complicate a lab study such as this by
skewing data, potentially leading to erroneous conclusions. However, these effects may be mitigated by
titration prior to testing, to determine batch concentrations prior to use. Titration was conducted during
the study to mitigate this effect.
2.7.2 Spor-Klenz® Ready-to-Use (RTU) Solution
Spor-Klenz® Ready-to-Use (RTU) is a broad-spectrum disinfectant and sporicide that is registered
with EPA under FIFRA (reg. no. 1043-119). Spor-Klenz® is a mixture of 1.0% hydrogen peroxide (H2O2),
0.08%) peroxyacetic acid, and 98.92% inert proprietary ingredients. The RTU version of Spor-Klenz® was
used in this study, as opposed to the concentrate (reg. no. 1043-120), to reduce the variation between
experiments. Spor-Klenz® RTU requires no dilution prior to use. A new container of Spor-Klenz® RTU
was used for each day of testing. Since Spor-Klenz® RTU is produced under manufacturer quality
11
-------
assurance criteria, only temperature was imposed as a critical measurement for this liquid (Table 7-1). The
product sheet for Spor-Klenz® states that it contains less than 10% acetic acid, 1% hydrogen peroxide,
and 0.08% peroxyacetic acid.
2.8 Sampling Strategy
Current surface sampling techniques are intrusive, as they are expected to remove viable spores
from the surface of the panel. Hence, sampling of positive controls was compared to post-decontamination
sampling of test panels for this study, rather than repeated sampling of the same area (before and after
decontamination). Positive controls and test panels were inoculated in the same manner. Positive control
panels were sampled, and the test panels were carried through the decontamination procedure, and
subsequently sampled. This concept has been employed in several standard quantitative methods. Wipe
sampling procedures were consistent with those reported by Brown et al. (Brown 2007).
2.8.1 Wipe Sampling
All panels were placed horizontally for sampling, regardless of their orientation during the
decontamination step. A sampling event log sheet (called "Panel Tracker") was maintained for each
sampling event (or test). The sampling team members' names, date, run number, and all sample codes
with corresponding panel codes were recorded on each sheet. Sample volumes, time of day, and
observations were written down in the laboratory notebook.
Polyester wipes (TX3211, Kernersville, NC) pre-wetted with Phosphate-buffered Saline with Tween 20
(PBST) were used for sampling the surface to recover residual spores. Briefly, one pass with the wipes
was made in one direction before making a second pass in an orientation -90 to the first one. The wipes
were dropped in 10 ml PBST, and vortexed to allow spores to be freely suspended. The number of spores
were estimated by plating 100-|il aliquots on two Tryptic Soy Agar (TSA) plates.
2.9 Runoff Analysis
Runoff samples were collected during the decontamination procedure. Liquid effluents from the
decontamination process were collected into sterilized containers (carboys). Runoffs are defined as excess
liquid decontaminant. Runoff samples were collected as one composite sample for each decontamination
test (composite of three test panels subjected to the decontamination procedure and composite of three
control panels). Total volume was estimated and two aliquots, each 8 ml, were added to 2 ml of 2M sodium
thiosulphate (STS) for immediate neutralization. Viable spore number was estimated in these samples.
The setup for spraying and run-off collection can be visualized below in Figure 2-5.
12
-------
Figure 2-5: Panel Holder Unit for Spray and Run-off Collection
2.10 Aerosol Sampling
Since spores may re-locate during the decontamination and sampling processes, glass fiber filters
(Pall Life Sciences, TCLP glass fiber filter Z268399, 47 mm diameter with 0.7 jam pore size) were used
for collecting settling spores following aerosolization. The filters were placed at a 3-ft height and analyzed
for spore numbers. One glass fiber filter was placed in proper position after the overnight spore settling
period. Air was pumped at a rate of 15L/min through the filters during spraying of control liquid or foam.
Further, the air was also sampled during a 30 min period after spraying liquid or foam disinfectant. After
the sampling process was completed, the filter was placed in a 50 mL tube containing 20 mL phosphate-
buffered saline with tween 20 and processed in the same manner as the other samples. The quantity of
viable spores collected were quantified by dilution plating. This assessment provided a qualitative
assessment of spore re-location during the decontamination application.
2.11 Microbial Analysis
Run-off samples, air filters, and wipe samples were all analyzed for presence of viable spores.
With the exception of run-off samples, all samples were extracted in PBST solution. Run-off samples
were collected in PBST + STS to neutralize disinfectant upon contact. The samples were appropriately
diluted in PBST before plating. An aliquot of either diluted or undiluted and extracted spore sample was
plated (2 plates/sample) on Tryptic soy agar plates. The plates were held at 37 ± 2 °C for 17 ± 3 hours.
The CFUs on plates were enumerated using a QCount (Model #510, Advanced Instruments, Norwood,
MA). Samples with no colonies were assigned a fixed value of one. Total CFUs per sample were
calculated by multiplying the mean number of CFUs on duplicate plates by the sample volume factor
(total volume of the collected sample), by the inverse of the dilution plated, and finally by the plated
volume factor (i.e., 10 for samples plated at 0.1 ml) to estimate total viable spores collected.
Mechanical removal of spores by the application of liquid or foam (controls, no decontaminant
added to liquid or foam) was estimated from spore recovery in the run-off. Surface Reduction was
calculated as mean Log spores (CFUs) collected by wipe samples from the control panel surface after
sprayed with water control - mean Log spores (CFUs) recovered from wipes of test panels sprayed with
13
-------
the test chemical. Finally, Decontamination Efficacy of the treatment was expressed as log reduction (LR),
and calculated from mean Log Total CFUs (control runoff + control surface wipes) - mean Log Total
CFUs (test runoff + test surface wipes).
14
-------
3.0 Quality Assurance/Quality Control
(QA/QC)
To ensure reliable data, the following data quality objectives and data quality indicators were established
and used throughout the study.
3.1 Data Quality Objectives
The data quality objectives (DQOs) were used to identify the critical measurements needed to
address the objectives of the test program and specify tolerable levels of potential errors associated with
data collection as well as the limitations of the use of the data.
The following measurements were deemed to be critical to accomplish the project objectives:
• pH and temperature of the pAB solution
• Sodium hypochlorite concentration via free available chlorine (FAC) of the pAB
decontamination solution
• CFUs per plate
• Total volume of decontaminant sprayed from backpack sprayer/foam sprayer
The following measurements were deemed non-critical but were monitored and recorded throughout the
entire testing schedule.
• pH of the Spor-Klenz® solution (used unaltered from manufacturer's container).
3.2 Data Quality Indicators
Data quality indicators (DQIs) for the critical measurements were used to determine if the collected
data met the quality assurance objectives. A list of these data quality indicators can be found in Table 3-
1.
Failure to provide a measurement method or device that would meet these goals would result in a rejection
of results derived from the critical measurement. Tests with conditions falling outside of these criteria
were rejected and repeated upon approval by EPA. Decisions to accept or reject tests were based upon
engineering judgment used to assess the likely impact of the parameter on the conclusions drawn from the
data.
15
-------
Table 3-1. DQIs for the Critical Measurements and Data Completeness Criteria
Measurement
Parameter
Analysis
Method
Accuracy
Target
Value
Acceptance
Criteria
Actual
Completeness
Na2S203/KI
FAC and pH in
pAB solution
titration
pFl meter
/NIST -traceable
buffer soln.
+/- 0.06 g/L
+/-0.01 pH
units
FAC
6,350
mg/mL
pH=6.8
6,000-6,700
mg/mL
6.5
-------
Replicate panels were included for each set of test conditions. Standard operating procedures using
qualified, trained and experienced personnel were used to ensure data collection consistency. The
confirmation procedure, controls, blanks, and method validation efforts were the basis of support for
biological investigation results. When necessary, training sessions were conducted by knowledgeable
parties, and in-house practice runs were used to gain expertise and proficiency prior to initiating the
research. If a high level of variability was observed, the test results were discussed with the EPA Project
Officer.
Additional DQIs specific to microbiological data are listed in Table 3-2.
Table 3-2. Additional Data Quality Indicators Specific to Microbiological Data
Panel or Sample Type
Acceptance
Criteria
Information
Provided
Results
Positive Control Panels
Sample from material
panel contaminated
with biological agent
and sampled using the
wipe method
1 x 107 for B.
atrophaeus
30% RSD
between
panels in each
test set
Shows viability of
wipe sampling
technique and plate's
ability to support
growth of B.
atrophaeus
Positive controls yielded
7.2 - 8.1-logs spores
Procedural Blank
Panel without
biological agent that
underwent the sampling
procedure
Non-detect
Controls for sterility
of materials and
methods used in the
procedure
Spore recoveries of 4-5
logs were common on
procedural blanks. Data
shown in Figure 4-7 and
discussed in Section 4.4.3.
Blank Plating of
Microbiological
Supplies
No observed
growth
following
incubation
Controls for sterility
of supplies used in
dilution plating
No colonies were observed
on blank TSA sterility
plates
Blank Tryptic Soy Agar
Sterility Control
Plate incubated, but not
inoculated
No observed
growth
following
incubation
Controls for sterility
of plates
No colonies were observed
on blank TSA incubated
overnight
Exposed Field Blank
Samples
A wipe kit will be
handled
Non-detect
The level of
contamination
present during
sampling
A few colonies (NON-BG)
were observed on 20%
occasions
17
-------
4.0 Results
4.1 Literature Review-based Selection of Dispensing Units
Numerous foam sprayers were identified which could be divided into three basic categories. Three
categories of sprayers included (1) manual and small capacity (i.e., up to 2 gallons) foam generators, which
include the Chapin industrial foamer/sprayer and Foam-it Pump-Up Foamer; (2)
electric/battery/compressed air driven and medium-capacity (i.e., up to 4 gallons) foam generators, such
as the Foam-it Foam Unit and SHURflow® pro pack; and (3) compressed air driven and large capacity
(i.e., 5-175 gallons) foam generators, like the Macaw compressed air foam system. Commercially-
available foam generating devices available at the time of the study can be found in Table 4-1.
Due to high viscosity of the gel base, typically high pressure and specialized nozzles are required for its
application. Airless paint sprayers (Graco®, Inc.) were highly recommended as gel applicators. These paint
sprayers are electrically powered and dispense gel at a relatively high velocity. Commercial gel applicators
available at the time of the study can be found in Table 4-2.
For this study, a single unit that could be used to spray liquid, foam and gel of a given disinfectant was
desired. Of the generators found, the Foam-it (Cat. #FI-5N, from Innovative Cleaning Equipment, Grand
Rapids, MI) was the only one to meet this requirement. By switching the nozzle, and using an appropriate
hose with an airline, this unit could be used to apply all three forms (liquid, foam, gel) of each
decontaminant. This unit was purchased from Innovative Cleaning Equipment through Armick (Grand
Rapids, MI). A second unit that was modified to have a drop bucket dispensing option and increased
suction was also purchased to be able to more easily dispense the gel. Despite these modifications, the
viscous nature of the gel did not allow it to be readily dispensed by the Foam-it unit. In order to have gel
applied to the required specifications, a switch was made to use the Graco® Airless paint sprayer for this
mode of application. This dispensing unit was only used for gel throughout the study, as the unit was
tested for spraying foam and it failed to dispense. Foam generation is a function of both foaming agent
and air. Since this unit is airless, it was unable to generate foam. Consequently, based on discussion with
the EPA, it was decided that the Foam-it unit would be used for dispensing liquid and foam and the
Graco® unit would be used for dispensing the gel formulation. No single spray device was identified that
was compatible with liquid, gel, and foam.
18
-------
Table 4-1: Foam Applicator Summary
Device
Manufacturer
Cat#
Cost
Capacity
Power
Requirements
Training
Special Remarks
Velocity
Pressure
Shelf-life
1
Macaw Backpack
Compressed Air Foam
(CAF) System
Intelagard®
$5,325 (List Price)
5 gal (19 L)
Battery
Operator's
manual outlines
use &
preventative
maintenance
checks
Charging: air
cylinder must be
refilled ("charged")
with air. Wash
complete system
after use. Always
add concentrate to
water when refilling
Vol (per squirt): ~5
gal/min; may vary
by 35% based on
nozzle sel. Proj.
dist: -30 ft (9.14 m)
Operating
pressure: ~100
psi (6.9 BAR);
110 psi maximum
Can be stored full
of water and Class
A or AFFF foam
concentrates for up
to 180 days if the
unit is protected
from freezing;
Should not be
stored in a ready
state if using decon
$599 (Nozzle Kit)
175 gal (662 L)
of finished foam
FOAM-iT Pump-Up
Foamer
Innovative
2L10X
0.5 qal (1.89 L)
Manual
2
Cleaning
5L10X
$40-68 (List Price)
1.32 qal (5 L)
Equipment
FI-2SL
2 qal (7.57 L)
FI-5N
5 gal (18.9 L)
Compressed
Air/Electric
Innovative
FI-10N
$600-2000 (List
Price)
10 qal (37.8 L)
3
FOAM-iT Foam Unit
Cleaning
FI-20N
20 qal (75.6 L)
Equipment
FI-25N
25 qal (94.5 L)
FI-30N
30 gal (13.4 L)
FI-50N
50 qal (189 L)
M1D-TP
Diesel
4
Diesel Powered Foamer
Armick, Inc.
NSN#:
4940-01-
588-9466
$8,650.00 (List
Price)
100 gal (378 L)
5
Pro Foam Variable
Control Foaming Sprayer
RL Flowmaster
RLF1997NF
S
$57.88
(Amazon.com)
2 gal (7.57 L)
Manual
6
Smith Performance
Sprayer (2 gal)
Smith
Performance
Sprayers
R200F
(#190456)
$53.85
(Amazon.com)
2 gal (7.57 L)
Manual
1054
$26.85
(Amazon.com)
0.375 gal (1.42
L)
Manual
7
Chapin Industrial
Chapin
2658E
$64.99
(Amazon.com)
1 gal (3.79 L)
Foamer/Sprayer
International, Inc.
2659E
$79.99
(Amazon.com)
2 gal (7.57 L)
2660E
$90.95
(Amazon.com)
3 gal (11.35 L)
8
B&G QT-1 Handheld
Sprayer with Adjustable
Tip
B&G Equipment
Co.
17017401
$31.85
(Amazon.com)
1.5 qt (0.95 L)
Manual
Charging - N/A;
Wash complete
system after
use.
Operating
pressure: 40 psi
demand switch.
Volume (per
squirt): varies
based on speed
settings (versatile)
Store in an upright
position with an
empty tank; relieve
pressure from the
discharge line &
wand; remove
power plug from the
battery jack.
9
SHURflo® SRS-600 Pro
Pack Rechargable
Backpack Sprayer
SHURflo®
SRS-600
$287.00
(Amazon.com)
4 gal (15.1 L)
Battery
10
Backpack Air foam
System;
http :/A/vww. cl erm ark. com/
d oc ume nts/c as cad. pdf
CI erm ark,
Canada
140sq-ft and 3
gal
Once mixed: min
4 hr up to 24 hr.
Used in
temperature ranges
of -20°C to + 55°C
(0°F to130°F)
11
TFT: PRO/pak
L.N. Curtis &
Sons
UM12NF
TFT
$775
2.5 gal (19 L);
2.5 gal foam
resivoir
Variable
velocity for inlet
pressures from
40-500 psi
Req's water source
attached via hose
13
Graco® Pro Pack™
Portable Spray Pack
Graco®
3A1292C
$145.21
(Amazon.com)
1 gal (3.79 L)
Battery
Note: Blank cells indicate data unavailable from vendor
19
-------
Table 4-2: Gel Applicator Summary
Device
Manufacturer
Cat#
Cost
Capacity
Power
Requirements
1
4000F-BP Forestry
Water Pump and
Backpack
Scotty Firefighter
4000F-BP
161.99 (FDC
Rescue Products )
5 gal (19)
None (pump
action)
2
Graco® ProShot HD
Graco®
16H960
$390.99 (Amazon
Price)
2 gal (7.57 L)
Battery
3
Graco® TrueCoat Pro II
Cordless Airless Sprayer
Graco®
16N657
$495.00 (Amazon
Price)
2 gal (7.57 L)
Battery
4
Graco® Xforce HD
Graco®
16N654
$3,271.00
(Grainger Price)
2 gal (7.57 L)
Battery
5
Graco® T rueCoat 360DS
Electric Handlheld Airless
Paint Sprayer
Graco®
17A466
$168.43 (Amazon
Price)
2 gal (7.57 L)
Electric
6
Wagner Flexio 590
Indoor/Outdoor Hand-
Held Sprayer
Wagner Power
Products
529010
$128.81 (Amazon
Price)
2 gal (7.57 L)
Electric
4.1.1 Selection of a Foaming Agent
In order for foam to be generated from a disinfectant, a foaming additive must be added to the
formulation. A review of foaming additives was completed and is summarized in Table 4-3. From the
summary list, two foaming agents, lauramine oxide (CAS #1643-20-5) and decylamine oxide (CAS
#2605-79-0) were tested for foam generation. At 10% concentration, both were found to be ineffective in
generating thick foam. Another foaming agent, Phos-Chek® WD881 Class A foam concentrate (ICL
Performance Products LP, AST 10045) was also tested at 10% concentration, and it generated the desired
lasting foam thickness. The concentration of Phos-Chek was lowered to 1% and still resulted in the same
thickness of foam. Phos-Chek was then evaluated via a modified AO AC International (AO AC) three-step
method using 5x5x1 glass coupons as carriers to quantitatively determine if the foaming agent would
affect the efficacy of the sporicides being used in the study (Rastogi, 2013). When tested against Spor-
Klenz and pH-adjusted Bleach, there was comparable spore recovery in control (water) samples vs. test
samples (Phos-Chek) as summarized in Figure 4.1 and Figure 4.2 respectively. Phos-Chek had a negligible
effect on efficacy of both sporicides. Due to the negligible effect on sporicidal efficacy and the generation
of a thick foam by 1% Phos-Chek, it was selected as the foaming additive for the study.
20
-------
Table 4-3: Foaming Additive Summary
Foaming Material
CAS#
Supplier
1
Lauramine Oxide
1643-20-5
Fisher Scientific,
Inc.
2
Decylamine Oxide
2605-79-0
Fisher Scientific,
Inc.
3
DOWFAX™ 3B2
(Alkyldiphenyloxide Disulfonate)
58318-10-8
Dow Chemical
Co.
4
DOWFAX™ 2A1
(Alkyldiphenyloxide Disulfonate)
12626-49-2
Dow Chemical
Co.
5
DOWFAX™ 8390
(Alkyldiphenyloxide Disulfonate)
-
Dow Chemical
Co.
6
DOWFAX™ C6L
(Alkyldiphenyloxide Disulfonate)
147732-60-3
Dow Chemical
Co.
7
DOWFAX™ C10L
(Alkyldiphenyloxide Disulfonate)
-
Dow Chemical
Co.
8
Cola®Lux LO (Lauramine
Oxide)
1643-20-5
Colonial
Chemical
9
Cola®Lux MO (Myristyl
Dimethylamine Oxide)
3332-27-2
Colonial
Chemical
10
Cola®Lux C-10 (Decylamine
Oxide)
2605-79-0
Colonial
Chemical
11
Cola®Lux C-8
(Octyldimethylamine Oxide)
260578-9
Colonial
Chemical
12
Cola®Lux 02 (Oleamine Oxide)
14351-50-9
Colonial
Chemical
13
Cola®Lux CAO-35
(Cocamidopropylamine Oxide)
68155-09-9
Colonial
Chemical
14
TRITON™ XN-45S Surfactant
-
Dow Chemical
Co.
15
Chemoxide™ CAW Surfactant
(Cocamidopropylamine Oxide)
68155-09-9
Essential
Ingredients, Inc.
16
AMMONYX® LMDO
(Lauryl/Myristyl Aminopropyl
Amine Oxide)
61792-31-2
67806-10-4
Stepan Co.
17
Chemoxide™ LO-PF
Surfactant (Lauramine Oxide)
1643-20-5
Essential
Ingredients, Inc.
18
PHOS-CHEK® WD881A
CLASS A FOAM
-
ICL
Performance
Products LP
Foaming agents could possibly impact decontamination efficacy. To ascertain possible interference of the
foaming agent with the decontamination agent, quantitative tests were performed in the lab using spores
of Bacillus atrophaeus. Efficacy of Spor-Klenz and pAB were tested in the presence of 1% Phos-chek.
The results are summarized in Figures 4.1 and 4.2.
21
-------
Figure 4-1: Effect of Phos-Chek on Spor-Klenz efficacy (10-minute exposure), using Bacillus
atrophaeus spores on glass
T3 „
a) 5
0)
>
0
1 4
o
O)
o
Log CFU of Bacillus atrophaeus Spores Recovered after
10 Minute Exposure to Spor-Klenz RTU and 1% Phos-Chek
l-I-lrX,
T DRun 1 ~
Run 2 DRun 3
JL
Titer/10 |jL Control 1% Phos-Chek Phos-Chek + Spor-Klenz
Spor-Klenz
Control Samples and Test
Figure 4-2: Effect of Phos-Chek on pH-adjusted Bleach efficacy (10-minute exposure), using B.
atrophaeus spores on glass
0)
>
O
O
£
o
O)
o
Log CFU of Bacillus atrophaeus Spores Recovered after 10
Minute Exposure to pAB and 1% Phos-Chek
~ Run1 DRun 2 QRun3
x^r1! JLr1!^
Titer/10 |jL Control 1% Phos-Chek Phos-Chek + pAB
pAB
Control Samples and Test
22
-------
The results show that 10 min contact with the two tested decontamination agents resulted in a 3-
4-log reduction in the number of viable spores on glass surfaces. Presence of foaming agent did not appear
to have any significant deleterious effect on any of the decontamination agents. These results verified that
Phos-chek was a suitable foaming agent for the remainder of the study.
4.2 Phase One: Small Scale Decontamination Application Variables
All experimental conditions for the evaluation of physical parameters were completed over a series
of eight runs, summarized in the test 1 of Table 4-4. Overall, a longer drying time was observed at higher
relative humidity and low temperature (Table 4-5). Wind velocity simulated via an oscillating fan did not
appear to play a significant role in drying time. Steel panels visually appeared to be dry within 15 minutes
when sprayed with liquid or foam. In contrast, concrete panels appeared to be visually wet within 30 min
of application. When treated with gel, a thin film was observed after 30 minutes with a significant amount
of gel dripping from both panel types. The majority of the gel had dripped from the panel within the first
6 minutes post-application. Figure 4-3 (A-H) summarizes the profile of wetness indicators on the concrete
panels under the eight conditions. Table 4-5 summarizes wetness analysis of the photographs for the steel
panels. Wetness analysis was difficult to ascertain from the pictures of concrete due to the color and porous
nature of the material and was therefore omitted. Figures 4-4 and 4-5 summarize the pictures based on
temperature, 50 °F and 90 °F respectively. Average time to complete (100%) dryness was >30 min and 6
min for foam, at 50°F and 90°F, respectively. For liquid, average time to complete dryness was 20.5 and
12.75 min, for 50°F and 90°F, respectively. Interestingly, these data suggest that foam may offer extended
wetted contact times at lower temperatures (i.e., 50°F), but liquid delivery resulted in longer wetted times
at the 90°F conditions.
23
-------
Table 4-4: Summary of Study Test Run Logs for Phase One Physical Parameters, Steel and
Concrete Surfaces
Parameter Study Test Lo<
T
Application
Temperature
°F
Relative
Hunidity
(%)
Wind
Condition
Test Date
Wind Velocity
Starting Conditions
Ending Conditions
Time
Temp
RH
Time
Temp.
RH
Liquid
50
25
No
5/22/2017
4:06 PM
43°
34%
4:38 PM
55°
45%
Foam
50
25
No
5/24/2017
10:33 AM
47°
24%
11:05 AM
52°
40%
Gel
50
25
No
5/24/2017
2:25 PM
48°
26%
2:58 PM
55°
33%
Liquid
50
25
Yes
5/19/2017
0.8 m/s @ 1'; 1.2 m/s @ 3'
1:42 PM
51°
26%
2:14 PM
51°
38%
Foam
50
25
Yes
5/19/2017
3:35 PM
52°
25%
4:06 PM
53°
43%
Gel
50
25
Yes
5/22/2017
2:27 PM
52°
27%
2:59 PM
54°
37%
Liquid
50
70
No
5/15/2017
2:40 PM
52°
69%
3:11 PM
52°
69%
Foam
50
70
No
5/15/2017
4:09 PM
51°
71%
4:40 PM
52°
76%
Gel
50
70
No
5/16/2017
2:01 PM
51°
71%
2:34 PM
49°
67%
Liquid
50
70
Yes
5/16/2017
1.0 m/s @ 1'; 1.5 m/s @ 3'
2:46 PM
49°
66%
3:19 PM
51°
72%
Foam
50
70
Yes
5/16/2017
3:41 PM
50°
67%
4:12 PM
53°
70%
Gel
50
70
Yes
5/16/2017
4:27 PM
48°
67%
4:58 PM
52°
72%
Liquid
90
25
No
5/17/2017
2:10 PM
90°
25%
2:42 PM
89°
28%
Foam
90
25
No
5/12/2017
4:15 PM
88°
26%
4:45 PM
87°
29%
Gel
90
25
No
5/12/2017
5:09 PM
89°
26%
5:50 PM
85°
27%
Liquid
90
25
Yes
5/17/2017
0.8 m/s @ 1'; 1.2 m/s @ 3'
2:56 PM
92°
26%
3.20 PM
88°
26%
Foam
90
25
Yes
5/17/2017
3:34 PM
88°
26%
4:05 PM
90°
28%
Gel
90
25
Yes
5/17/2017
4:38 PM
91°
25%
5:10 PM
O
GO
00
26%
Liquid
90
70
No
5/5/2017
2:56 PM
89°
66%
3.35 PM
89°
69%
Foam
90
70
No
5/5/2017
3:34 PM
92°
67%
4:15 PM
87°
76%
Gel
90
70
No
5/5/2017
4:38 PM
88°
67%
5:05 PM
85°
67%
Liquid
90
70
Yes
5/8/2017
.96 m/s @ 3'; 0.66 m/s @ 6
9.30 AM
91°
69%
10.05 AM
88°
72%
Foam
90
70
Yes
5/8/2017
11.10 AM
88°
71%
11.40 AM
90°
70%
Gel
90
70
Yes
5/8/2017
12:30 PM
91°
71%
1.10 PM
88°
72%
Highlighted values indicate readings outside the acceptance criteria of+/- 10%. Despite deviating from the
OA criteria, values were utilized in study results due to system limitations of maintaining the said conditions.
24
-------
Figure 4-3 (A-H): Wetness value profile under four ambient conditions with fan on/off
A.
Wetness Profile for Vertical Concrete at 90°F and 70% RH with
No Wind
80
70
Liquid
Gel
Foam
Baseline
60
£ 50
(/)
0 40
$
30
20
0
5
10
15
20
25
30
35
Minutes after Application
B
Wetness Profile for Vertical Concrete at 90°F and 70% RH with
Wind
60
Liquid
Gel
Foam
Baseline
50
-------
Wetness Profile for Vertical Concrete at 90°F and 25% RH
with No Wind
Liquid
Gel
Foam
Baseline
60
0
£
20
0
5
10
15
20
25
30
35
Minutes after Application
Wetness Profile for Vertical Concrete at 90°F and 25% RH with
Wind
70
60
Liquid
Gel
Foam
Baseline
50
^ 40
-------
Wetness Profile for Vertical Concrete at 50°F and 70% RH with No
Wind
45
Liquid
Gel
Foam
Baseline
40
w
w 25
c
20
0
5
10
15
20
25
30
35
Minutes after Application
Wetness Profile for Vertical Concrete at 50°F and 70% RH with
Wind
70
60
Liquid
Gel
Foam
Baseline
C? 50
0s
(/)
a> 40
c
30
20
0 5 10 15 20 25 30 35
Minutes after Application
27
-------
Wetness Profile for Vertical Concrete at 50°F and 25% RH with
Wind
-------
Table 4-5: Steel Picture Analysis
Steel Picture Analysis
Condition
Application
50% Dry Time
100% Dry Time
50°F, 25% RH, No fan
Liquid
12 min
20 min
Foam
9 min
>30 min
50°F, 25% RH, Fan
Liquid
6 min
12 min
Foam
3 min
>30 min
50°F, 70% RH, No fan
Liquid
12 min
30 min
Foam
6 min
>30 min
50°F, 70% RH, Fan
Liquid
6 min
20 min
Foam
3 min
>30 min
90°F, 25% RH, No fan
Liquid
3 min
9 min
Foam
3 min
3 min
90°F, 25% RH, Fan
Liquid
3 min
6 min
Foam
3 min
3 min
90°F, 70% RH, No fan
Liquid
20 min
30 min
Foam
3 min
9 min
90°F, 70% RH, Fan
Liquid
3 min
6 min
Foam
6 min
9 min
Analysis was conducted for all available photos. Analysis was not conducted for gel application as while
much gel ran off due to vertical orientation, the panel was still wet at 30 min. It should also be noted that it
was hard to maintain conditions at 50°F and 25% RH (and increased humidity at this time point may have
allowed panels to stay wet longer). High temperature appears to play a greater role in dry time than relative
humidity (halving the dry time vs. no significant change), with wind conditions leading to only slight variation
(±3 minutes).
29
-------
Figure 4-4: 90°F Picture Assembly
90°F, 25% RH, No Fan
Application
Minutes after Application
Foam
-------
90°F, 25% RH, Fan
Application
Minutes after Application
Foam
.1
~ mK f
V -
W*
31
-------
90°F, 70% RH, No Fan
Application
Minutes after Application
Foam
32
-------
90°F, 70% RH, No Fan
Application
Minutes after Application
Foam
33
-------
Figure 4-5: 50 °F Picture Assembly
50°F, 25% RH, Fan
Application
Minutes after Application
'
Foam
34
-------
50°F, 25% RH, No Fan
Application
Minutes after Application
Gel
I
12
1
L
i
81
I
30
Foam
~n
I
35
-------
50°F, 70% RH, No Fan
Application
Minutes after Application
Foam
i
i
36
-------
50°F, 70% RH, Fan
Application
Minutes after Application
Liquid
Foam
Gel
ft:"' '
1
¦m
"
EX
12
k*\
30
37
-------
4.3 Testing Issues and Observations
During phase one testing, the base gel procured from the vendor had viscosity that allowed it to be
spray-dispensed. However, prior to use in decontamination tests, the base gel needed to be amended
(diluted) with sporicidal chemical. In previous studies performed by ECBC (Rastogi 2016), it was
determined that nine parts of gel mixed with one-part sporicidal chemical resulted in an ideal viscosity. In
these previous studies, the base gel was requested from the vendor to have 10% water content removed,
so that when amended with 10% v/v sporicidal chemical, the gel's rheological properties were ideal. CBI
Polymer (ECBC collaborator) performed this minor alteration of the base gel. CBI Polymer, Inc. has been
acquired by Metis Chemical Co., and customized gel requests are not possible from the current vendor. A
modified gel with appropriate viscosity was never received from the vendor, thus no gel formulation
received could be effectively sprayed using an airless sprayer after preparation. Consequently, sporicidal
efficacy with gel application had to be abandoned. Liquid and foam could be sprayed using the Foam-it
unit but required the use of an air compressor. Lastly, significant rusting was observed on steel panels,
and therefore these could not be re-used. For coupon re-use, stainless steel 316 should be used.
4.4 Phase Two: Chamber Decontamination Testing
4.4.1 Comparative Sporicidal Efficacy of pAB and Spor-Klenz Applied as Liquid vs.
Foam
Based on the results of phase one, two contrasting ambient test conditions were selected: 50
°F/70% RH and 90 °F/25% RH. Since wind (as simulated with fan) made no significant difference on
drying times, all the decontamination efficacy testing was conducted with NO fan (no simulated wind),
with system controls maintained to limit the variability of test conditions.
4.4.2 Spore Recovery from Control panels
For this study, B. atrophaeus spores were deposited as aerosol powder on concrete and steel panels
placed horizontally on the floor surface. It was important to first determine that the spore deposition was
uniform on panels placed across the floor. Two positive control types included panels that were wipe-
sampled without further treatment, and panels that were sprayed with water as liquid or as foam, and run-
off was collected; residual spores remaining on the panel surfaces were determined by wipe-sampling.
Figure 4.6 below summarizes the portioning of spores in run-off and those retrieved by surface wipe-
samples. The results show a significant number of spores (7.2-7.8-logs) were mechanically removed by
spraying action. It appears that wipe-samples recovered approximately 10-fold more spores from steel
surfaces than concrete. Overall, comparable numbers of spores (7.6-logs + 0.3-logs SD) were recovered
from control panels in eight independent spore deposition runs, suggesting that depositions were
consistent across tests.
38
-------
Figure 4-6: Spore Recovery and Partitioning from Control Panels
10
9
8
_ 7
s
LL c
O b
o
d) 5
£
a)
> ^
o °
o
& 2
1
0
Recovery (+/- SD) of Bacillus atrophaeus Spores from Control
Panels with Water Sprayed as Liquid or Foam
¦ Run Off Liquid ~ Run Off Foam
~ Surface Wipe (Liquid) ~ Surface Wipe (Foam)
I
1
50/70 Concrete 50/70 Steel 90/25 Concrete 90/25 Steel
Environmental Conditions (°F/%RH) and Surface Type
4.4.3 Spore Recovery from Control Panels by Wipes and Spore Reaerosolization
Analysis
In this study, one set of controls included procedural negative blanks (with no spore deposition).
Since spore inoculated panels were 12 x 12 inches, wipe-sampling was utilized rather than extraction-
based sampling. During the decontaminant spray application, it was expected that a fraction of spores
would be aerosolized. In order to assess spore reaerosolization potential, air samples were collected
adjacent to test panels at a height of 3-ft, using a collection rate of 15-L/min, for 10 minutes. As mentioned
before, air was sampled during spraying of control liquid or foam. Additionally, the air was sampled
during a 30 min contact time after spraying disinfectant liquid or foam. Spore recoveries from air filters
and from procedural blanks, along with maximal spore recovery through wipes data, is summarized in
Figure 4.7. The results show 4-5 logs of spores recovered from procedural blanks. It is hypothesized that
blank panel contamination may have occurred during the sampling of panels, as they were moved into the
chamber alongside test coupons prior to sampling. The chamber was not volumetrically decontaminated,
nor verified clean prior to moving the blanks. Alternative handling of procedural blanks is advised for
future experimentation. Unfortunately, it is assumed that similar contamination of experimental coupons
occurred. Thus, post-decon test panel recoveries in the 4 to 5 log CFU range cannot be distinguished from
potential contamination. Fortunately, post-decontamination surface recoveries on test panels were
typically in the 5 to 6 log CFU range, and contamination would therefore have a minimal (~1 to 10%)
impact on efficacy estimates. The results also show a relatively small fraction of spores being aerosolized
from the surfaces (4-logs); however, the recoveries from air should be considered qualitative rather than
quantitative. Finally, the maximal spores recovered from positive controls averaged 8-logs/panel. This
39
-------
average value is derived from a set of six panels with standard deviation of 0.4-logs. The total spore
recovery data are summarized in Figure 4.8. The results show 7.2-7.8-logs spore recovery from positive
controls of both panel types.
Figure 4-7: Spore Recovery with Wipes and Reaerosolization Analysis
10
3
LL
O
o
T—
O)
o
0)
>
° A
o 4
-------
decontamination efficacy on steel and concrete surfaces in the vertical orientation. This observation was
counter-intuitive, since foam was expected to extend the wetted contact time on the vertical test surfaces
when compared to liquid.
Figure 4-8 Comparative Decontamination Efficacy of pAB and Spor-Klenz RTU (SK) Applied as
Liquid or Foam
Surface Decontaimination Efficacy of Two Disinfectants
Applied as Foam or Liquid
c
o
"5
O
3
T3
a)
0£
U)
o
o
(0
o
£
HI
c
o
o
a)
a
0
_L
¦ pAB Liquid
~ SK Liquid
~ pAB Foam
~ SK Foam
_L
50/70 Concrete 50/70 Steel 90/25 Concrete 90/25 Steel
Environmental Conditions (°F/%RH) and Surface Type
41
-------
5.0 Conclusions and Future
Recommendations
The objective of this study was to compare and evaluate relative effectiveness of three
decontaminant carrier media: liquid, foam, and gel. Evaluations were conducted by attempted
decontamination of concrete and steel surfaces in the vertical orientation, with one application and a 30-
minute wetted contact time. Spores of B. atrophaeus, a surrogate for the pathogenic B. anthracis Ames
strain, were aerosolized within a test chamber containing 12 x 12 inch steel and concrete panels.
Unfortunately, prior to conducting the efficacy study, the gel application approach had to be abandoned
due to the vendor's inability to provide an appropriate base gel that could be sprayed after formulation
with addition of disinfectant.
In order to determine spore physical removal during the spray application process, 1) run-off
samples during decontaminant application were neutralized immediately upon collection, to offer a
conservative estimate of potential exfiltration of viable contaminants during the spray application; and 2)
a set of controls were sprayed with water (rather than sporicidal chemical), so that differences in run-off-
collected and surface-collected spores could be attributed to killing by the decontaminant. Differences in
surface recoveries, between panels sprayed with water (control) and those sprayed with decontaminant,
provide an estimation of surface reduction efficacy of the test chemical. Finally, to estimate total
decontamination efficacy, both fractions of viable spores recovered (i.e., run-off and post-treatment
surface-collected spores) are added and their mean log values subtracted from equivalent values for panels
sprayed with water (controls). The difference, or "log reduction" values between the two, provides a
holistic estimate of total decontamination efficacy.
Overall, spore recovery data from 12 x 12 inch concrete and steel positive control panels showed
consistent spore deposition (7.2-7.8-logs) on 1 ft2 surfaces. Greater than 7-logs of spores were recovered
in run-off samples when sprayed with water, demonstrating that a significant number of spores can be
mechanically removed from the test surfaces. Spores were also detected in air samples, demonstrating the
potential for reaerosolization. A significant fraction of spores deposited (~4-6-logs) survived the
decontaminant treatments and were recovered from surfaces by wipe-sampling, while a smaller proportion
of viable spores were detected in the runoff fraction of the test samples (3.11 to 4.92-logs).
A summary of the decontamination efficacy data for pAB and Spor-Klenz tests is presented in
Tables 5-1 and 5-2, for the high temperature (90 °F / 25% RH) and low temperature (50 °F/70% RH)
conditions, respectively. Poor efficacy of peroxide-based sporicidal chemicals on concrete surfaces is
well-documented, and the results summarized in this study do not contradict this trend (Figure 4-8 and
Tables 5-1 and 5-2). Efficacy of Spor-Klenz on concrete was lowest at the low temperature condition, and
efficacy at the high temperature condition was similar to that of pAB. In fact, total decontamination
efficacy across all tests was not statistically different between the two material types (paired t-test, p =
0.39) (Table 5-3). The sporicidal efficacy of pAB and Spor-Klenz on steel surfaces did not vary across
the two environmental conditions (paired t-test, p = 0.39) (Table 5-3). The data show comparable efficacy
of liquid and foam, when considering each of the two decontaminants individually (i.e., foam delivery of
either pAB or Spor-Klenz did not enhance efficacy over liquid delivery) (paired t-test, p = 0.18) (Tables
5-1, 5-2, and 5-3). When comparing the data (pooled for all conditions except the contrast being evaluated)
by paired t-test, across independent variables (test conditions), four contrasts were significant at the 0.05
alpha level: 1) temperature-dependent differences were noted for surface efficacy (p = 0.000007, with low
temperature achieving higher efficacy (3.73 LR) over low temperature (1.74 LR); 2) temperature-
dependent differences were noted for runoff recoveries (p = 0.0026, with high temperature achieving
42
-------
higher recoveries in the runoff, 3.8 versus 1.6 log CFU); 3) significant differences (p = 0.011) were
observed in runoff recovery between liquid (2.4 log CFU recovered) and foam (3.016 log CFU recovered);
and 4) a significant difference in surface reduction was noted between foam and liquid (p = 0.04, 2.86 LR
with foam and 2.6 LR with liquid). Total decontamination efficacy was not significantly different across
any of the independent variable contrasts (temperature, material, or decontaminant media). While this
limited test series did not demonstrate significant advantage of foam application over that of liquid, further
evaluations should be conducted. From Phase I data (Table 4-5), it was apparent that foam may extend
wetted contact duration under some conditions (tests at 50°F). Average time to complete (100%) dryness
was >30 min and 6 min for foam, at 50°F and 90°F, respectively. For liquid, average time to complete
dryness was 20.5 and 12.75 min, for 50°F and 90°F, respectively. Interestingly, these data suggest that
foam may offer extended wetted contact times at lower temperatures (i.e., 50°F), but liquid delivery
resulted in longer wetted times at 90°F conditions. However, as these differences may be an artifact of
test and measurement variability, further tests should be conducted to more extensively compare the
decontaminant media type's effect on surface wetness duration.
43
-------
Table 5-1: Spore removal, surface reduction and decontamination efficacy for Spor-Klenz (A) and pAB application (B) at 90 °F and
25% RH
A.
Spor-Klenz RTU Decon Efficacy
90° F, 25% RH
Liquid
Foam
Recovery (Log CFU)
Decon Efficacy (LR)
Recovery (Log CFU)
Decon Efficacy (LR)
Run Off
(Liquid)
Surface
(Wipe)
Surface
Reduction1
Total
Reduction2
Run Off
(Liquid)
Surface
(Wipe)
Surface
Reduction1
Total Reduction2
Concrete
Control
8.01
6.05
0.48
2.43
7.63
7.21
2.07
2.69
Test
3.80
5.16
3.93
5.14
Steel
Control
7.96
6.90
0.95
1.80
7.91
7.31
1.32
2.19
Test
3.11
6.14
3.31
5.98
1. Surface Reduction = Log CFU recovered by wipe sampling after surfaces were sprayed with water - Log CFU recovered by wipe sampling after sprayed with test
chemical
2. Total Reduction = Total Log CFU (control) - Total Log CFU (test)
B.
pH-ad justed Bleach Decon Efficacy
90° 1
F, 25% RH
Liquid
"oam
Recovery (Log CFU)
Decon E,fficacy (LR)
Recovery (Log CFU)
Decon E,fficacy (LR)
Run Off
(Liquid)
Surface
(Wipe)
Surface
Reduction1
Total
Reduction2
Run Off
(Liquid)
Surface
(Wipe)
Surface
Reduction1
Total Reduction2
Concrete
Control
8.01
6.05
1.75
3.49
7.63
7.21
2.41
2.84
Test
3.76
4.50
3.80
4.72
Steel
Control
7.96
6.90
1.28
3.20
7.91
7.31
1.51
1.90
Test
3.74
5.47
4.92
5.85
1. Surface Reduction = Log CFU recovered by wipe sampling after surfaces were sprayed with water - Log CFU recovered by wipe sampling after sprayed with test
chemical
2. Total Reduction = Total Log CFU (control) - Total Log CFU (test)
44
-------
Table 5-2: Spore removal, surface reduction and decontamination efficacy for Spor-Klenz (A) and pAB application (B) at 50 °F and
70% RH
A.
Spor-Klenz RTU Decon Efficacy
50° F, 70% RH
Liquid
Foam
Recovery (Log CFU)
Decon Efficacy (LR)
Recovery (Log CFU)
Decon E,fficacy (LR)
Run Off
(Liquid)
Surface
(Wipe)
Surface
Reduction1
Total
Reduction2
Run Off
(Liquid)
Surface
(Wipe)
Surface
Reduction1
Total Reduction2
Concrete
Control
7.90
6.57
0.46
1.32
7.50
7.27
0.87
1.32
Test
3.33
6.32
3.53
6.36
Steel
Control
7.76
7.42
1.46
2.26
7.58
7.93
2.81
2.92
Test
3.87
6.33
3.36
5.51
1. Surface Reduction = Log CFU recovered by wipe sampling after surfaces were sprayed with water - Log CFU recovered by wipe sampling after sprayed with test
chemical
2. Total Reduction = Total Log CFU (control) - Total Log CFU (test)
B.
pH-ad justed Bleach Decon Efficacy
5(
)° F, 70% RH
Jquid
Foam
Recovery (Log CFU)
Decon Efficacy (LR)
Recovery (Log CFU)
Decon Efficacy (LR)
Run Off
(Liquid)
Surface
(Wipe)
Surface
Reduction1
Total
Reduction2
Run Off
(Liquid)
Surface (Wipe)
Surface
Reduction
Total Reduction
Concrete
Control
7.90
6.57
1.02
3.04
7.50
7.27
2.4
2.72
Test
3.79
5.00
4.12
4.90
Steel
Control
7.76
7.42
1.92
3.61
7.58
7.93
2.09
2.67
Test
3.79
5.08
4.05
5.32
1. Surface Reduction = Log CFU recovered by wipe sampling after surfaces were sprayed with water - Log CFU recovered by wipe sampling after sprayed with test
chemical
2. Total Reduction = Total Log CFU (control) - Total Log CFU (test)
45
-------
Table 5-3: Paired t-test Results
Runoff Recovery
Surface Reduction
Total Reduction
Low vs. High Temp
0.0003
0.000007
0.39
Steel vs. Concrete
0.129
0.06
0.39
Liquid vs. Foam
0.011
0.04
0.18
Note: Bold values significant at 0.05 alpha
Finally, based on the results summarized in this study, future work may be warranted in the following
areas:
1. Additional porous and non-porous surface types could be evaluated.
2. Other decontaminant types could be evaluated.
3. Additional applications and longer contact times could be evaluated, to determine more
effective conditions (not a goal of the current study).
4. Surface orientations other than vertical could be evaluated (e.g., horizontal, inverted, and
angled).
5. DeconGel applicability, once a sprayable version of base gel can be procured from the vendor.
46
-------
6.0 Literature Cited
1. Brown, G.S., Betty, R.G., Brockmann, J.E., Lucero, D.A., Souza, C.A., Walsh, K.S., Boucher,
R.M., Tezak, M., Wilson, M.C., and Rudolph, T. "Evaluation of a wipe surface sample method for
collection of Bacillus spores for nonporous surfaces." Applied Environmental Microbiology 73(3)
(2007): 706-10.
2. Canter, D.A., Gunning, D., O'Connor R.P., Traunero, C. and Kempter, C.J. "Remediation of
Bacillus anthracis contamination in the U. S. Department of Justice mail facility." Biosec. & Bioterr
3 (2005): 119-127.
3. Calfee, M.W., Ryan, S., Wood, J., Mickelsen, L., Kempter, J.C., Miller, L., Michelle Colby, M.,
Touati, A., Clayton, M., Griffin-Gatchalian, N., McDonald, S., and Delafield, F. "Laboratory
Evaluation of Large-Scale Decontamination Approaches." Journal of Applied Microbiology 112
(5) (2012): 874-882.
4. Rastogi, V.K., Smith, L.S., Wallace, L., and Tomasino, S.F. "Modified AO AC three step method
(official method 2008.05): consolidation of fractions B and C " Journal of AO AC International
95(5) (2013): 947-50.
47
-------
7.0 Appendices
Appendix A: Parameter Studies- 90°F Full Picture Assembly
W
48
-------
Appendix B: Parameter Studies- 50°F Full Picture Assembly
49
-------
vvEPA
United States
Environmental Protection
Agency
PRESORTED STANDARD
POSTAGE & FEES PAID
EPA
PERMIT NO. G-35
Office of Research and Development (8101R)
Washington, DC 20460
Official Business
Penalty for Private Use
$300
------- |