United States
Environmental Protection
Agency
Building Decontamination Alternatives
Office of Research and Development
National Homeland Security
Research Center
                                            w> "^ *', < -""'.'}'.'. ^'VVt,,/
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                                             EPA/600/R-05/036
                                                  March 2005
                                                                 i
    COMPILATION OF AVAILABLE DATA ON
BUILDING DECONTAMINATION ALTERNATIVES
                      Prepared by

         Science Applications International Corporation
                 11251 Roger Bacon Drive
                   Reston, VA  20190

               EPA Contract No. 68-C-02-067
              EPA Work Assignment (WA) 1-31
                     Prepared for

            U.S. Environmental Protection Agency
          National Homeland Security Research Center
             Office of Research and Development
                 Washington, B.C. 20460

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                             EPA DISCLAIMER NOTICE
       This report was prepared in an effort to promptly provide as much information as
possible on technologies that could potentially be utilized in decontamination of a building that
has been subjected to a chemical or biological attack. As a result, this report has compiled large
amounts of data from a variety of sources, often including the vendors of the technologies being
addressed. It has not been possible to independently evaluate the data that are presented.
Accordingly, the appearance of data in this report should not be interpreted as implying EPA
validation of these data, or of the experimental protocols or quality assurance measures used in
generating the data.

       Mention of trade names or commercial products does not constitute endorsement or
recommendation of their use.
                                          U-S
                                            w""'
                                           11

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                                     ABSTRACT
In September 2002, the U.S. Environmental Protection Agency (EPA) created the National
Homeland Security Research Center (NHSRC) within the Agency's Office of Research and
Development (ORD). As one of the elements within NHSRC, the Safe Buildings Team has, as a
key part of its responsibilities, engineering and economic analysis of alternative technologies and
approaches for decontaminating buildings following an attack using chemical and biological
(CB) agents.

As an initial step in this Safe Buildings Team decontamination program, NHSRC commissioned
this state-of-the-art report, to provide background information regarding potential building
decontamination technologies. This review of decontamination technologies is intended to: 1)
assist NHSRC in prioritizing the technologies to be evaluated under its decontamination
program; and 2) serve as an educational tool for the various NHSRC clients interested in
building decontamination.

This document presents an analysis of selected technologies that have been tested for their
potential effectiveness in decontaminating a building that has been attacked using biological or
chemical warfare agents, or using toxic industrial compounds. The technologies selected to be
addressed here fall into three broad categories:

    •   Liquid-based topical agents, including hypochlorite (bleach), aqueous chlorine dioxide,
       aqueous hydrogen peroxide, and a proprietary product (TechXtract).

    •   Foams and gels, including Sandia Foam and Decon Green, CASCAD, and L-Gel.

    •   Gaseous and vapor technologies (fumigantsX including chlorine dioxide gas, vapor-phase
       hydrogen peroxide, paraformaldehyde, and methyl bromide.

Each of these technologies is reviewed in terms of its principles of operation, technical maturity,
available data, concerns for the user, commercial availability, and advantages and disadvantages.
No single technology is applicable in all situations; some technologies are better selections than
others. As a broad generality, liquids are effective cleaners of non-porous surfaces, but may
cause corrosion or degradation of the surface. Foams and gels have shown some promising
results against both biological and chemical contaminants, but present post-decontamination
cleanup issues, and require further demonstration. Gases and vapors have been demonstrated to
be effective in destroying biological contamination under controlled conditions (e.g., in
sterilization chambers) and, in some cases, in field remediations, but have not been effective in
removing chemical contamination,  and warrant further demonstration under the less well
controlled conditions that exist during fumigation of a large building.

This document has been peer and administratively reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Mention of trade names or commercial
products does not constitute endorsement  or recommendation of their use.
                                          111

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                                               TABLE OF CONTENTS

                EPA Disclaimer Notice	 ii
                Abstract 	iii
                List of Figures 	viii
                List of Tables	ix
                Acknowledgments	xi

                1.     EXECUTIVE SUMMARY	1
                       1.1    Objective 	1
                       1.2    Decontamination Technologies Addressed in this Document	1
                       1.3    Summary of Technology Status 	<.	2
                       1.4    Identification of Areas for Potential Research	9
                       1.5    The NHSRC Program to Address these Research Areas	11

                2.     INTRODUCTION	13
                       2.1    Scope, Purpose, and Summary	13
                       2.2    Summary of Decontamination Technologies Selected for Evaluation	13
                             2.2.1  Surface-Applied Technologies Considered	14
                             2.2.2 Gas- and Vapor-Phase Technologies Considered	-	17
                             2.2.3 Other Technologies Considered	19
                       2.3    Broad Review of Categories of Alternatives with Potential Applications 	20
                       2.4    References for Section 2 . .t	21

                3.     LIQUID-BASED TECHNOLOGIES  	23
                       3.1    Hypochlorite  	23
                             3.1.1  Technology Description	23
                             3.1.2 Technical Maturity	24
                             3.1,3 Applications of the Technology	26
                             3.1.4 Compilation of Available Data 	27
i                             3.1.5 Concerns for the User (Applicability)	29
1                             3.1.6 Availability of the Technology for Commercial Applications 	30
                             3.1.7 Advantages and Disadvantages	30
                             3.1.8 Potential Areas for Future Research (Uncertainties)	31
                             3.1.9 References for Section 3.1	31
                       3.2    Aqueous Chlorine Dioxide  	32
                             3.2.1  Technology Description	32
                             3.2.2 Technical Maturity	32
                             3.2.3 Applications of Aqueous Chlorine Dioxide	32
                             3.2.4 Compilation of Available Data	32
                             3.2.5 Concerns for the User  	39
                             3.2.6 Availability of the Technology for Commercial Applications 	40
                             3.2.7 Advantages and Disadvantages	40
                             3.2.8 Potential Areas for Future Research 	41
                             3.2.9 References for Section 3.2	41
                                                          IV

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       3.3    Liquid Hydrogen Peroxide	43
             3.3.1  Technology Description	43
             3.3.2  Technical Maturity	44
             3.3.3  Applications of the Technology	44
             3.3.4  Compilation of Available Data 	45
             3.3.5  Concernsforthe User	52
             3.3.6  Availability of the Technology for Commercial Applications 	52
             3.3.7  Advantages and Disadvantages	52
             3.3.8  Potential Areas for Future Research  	53
             3.3.9  References for Section 3.3	53
       3.4    TechXtract® Contaminant Extraction Technology  	55
             3.4.1  Description of the Technology Alternative	55
             3.4.2  Technical Maturity 	58
             3.4.3  Applications of the Technology	58
             3.4.4  Compilation of Available Data	59
             3.4.5  Concerns for the User  	62
             3.4.6  Availability of the technology for commercial applications	63
             3.4.7  Advantages and Disadvantages	64
             3.4.8  Potential Areas for Future Research  	65
             3.4.9  References for Section 3.4	;	65

4.      FOAM AND GEL TECHNOLOGIES  	67
       4.1    Sandia Foam and Decon  Green	*	67
             4.1.1  Technology Description	67
             4.1.2  Technical Maturity	68
             4.1.3  Applications of the Technology	68
             4.1.4  Compilation of Available Data 	69
             4.1.5  Concerns for the User  	75
             4.1.6  Availability of the Technology for Commercial Applications 	75
             4.1.7  Advantages and Disadvantages	77
             4.1.8  Potential Areas for Future Research  	78
             4.1.9  References for Section 4.1	78
       4.2    Canadian Aqueous System for Chemical-Biological Agent Decontamination
             (CASCAD®)	80
             4.2.1  Technology Description	80
             4.2.2  Technical Maturity	81
             4.2.3  Applications of the Technology	82
             4.2.4  Compilation of Available Data 	82
             4.2.5  Concerns for the User  	85
             4.2.6  Costs	85
             4.2.7  Advantages and Disadvantages	85
             4.2.8  Potential areas for Future Research	85
             4.2.9  References for Section 4.2	86

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       4.3    L-Gel  	87
             4.3.1   Description of the Technology Alternative	87
             4.3.2   Technical Maturity  	'.	88
             4.3.3   Applications of the Technology  	'	89
             4.3.4   Compilation of Available Data		89
             4.3.5   Concerns for the User  	93
             4.3.6   Availability of the Technology for Commercial Applications  	93
             4.3.7   Advantages and Disadvantages	93
             4.3.8   Potential Areas for Future Research  	94
             4.3.9   References for Section 4.3	94

5.      GAS AND VAPOR TECHNOLOGIES  	97
       5.1    Chlorine Dioxide	97
             5.1.1   Description of the Technology 	97
             5.1.2   Methods for the Generation of Chlorine Dioxide 	98
             5.1.3   Applications for Chlorine Dioxide  	100
             5.1.4   Compilation of Available Data 	101
                    5.1.4.1 Data from laboratory and trailer testing	101
                    5.1.4.2 Experience with field fumigation of buildings 	116
             5.1.5   Concerns for the User  	126
             5.1.6   Availability of the Technology for Commercial Applications  	126
             5.1.7   Cost for generation of C102	131
             5.1.8   Advantages and Disadvantages	131
             5.1.9   Potential Areas for Future Research  	132
             5.1.10 References for Section 5.1	132
       5.2    Vapor Hydrogen Peroxide	136
             5.2.1   Description of the Technology Alternative	136
             5.2.2   Technical Maturity	137
             5.2.3   Applications for Hydrogen Peroxide Vapor	138
             5.2.4   Compilation of Available Data	 139
                    5.2.4.1 Data from laboratory testing  	139
                    5.2.4.2 Experience with field fumigation of buildings 	143
             5.2.5   Concerns for the User  	147
             5.2.6   Availability  of the Technology for Commercial Applications  	148
             5.2.7   Advantages and Disadvantages	148
             5.2.8   Potential Areas for Future Research  	148
             5.2.9   References for Section 5.2	149
       5.3    Paraformaldehyde   	151
             5.3.1   Description of the Technology Alternative	151
             5.3.2   Technical Maturity	152
             5.3.3   Applications of the Technology	152
             5.3.4   Compilation of Available Data 	153
             5.3.5   Concerns for the User  	163
             5.3.6   Availability  of the Technology for Commercial Applications  	164
             5.3.7   Advantages and Disadvantages	165
             5.3.8   Potential Areas for Future Research  	165

                                          vi

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       5.3.9  References for Section 5.3	165
5.4    Methyl Bromide 	'. 168
       5.4.1  Description of the Technology  	168
       5.4.2  Technical maturity	168
       5.4.3  Applications of the technology  	168
       5.4.4  Compilation of available data	169
       5.4.5  Concerns for the User	178
       5.4.6  Availability of the technology for commercial applications	179
       5.4.7  Advantages and Disadvantages	180
       5.4.8  Potential areas for future research	180
       5.4.9  References for Section 5.4	181
                                    VII

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                                 LIST OF FIGURES

Figure 3.4-1. Locations of Wipe and Coring Samples	61
Figure 4.1-1. EPA Test Data for EasyDECON 4215	73
Figure 4.2-1. Demonstration of the Foam Application on a Tank Vehicle 	81
Figure 4.3-1. L-Gel, Delivered as Semisolid, is Liquified for Use	88
Figure 5.1-1. Log of Colony Forming Units (cfus) Remaining at Each Time Point for Trial 11;
      Laboratory Validation of Chlorine Dioxide Decontamination  	104
Figure 5.1-2. Log of Colony Forming Units (cfus) Remaining at Each Time Point for Trial 9;
      Laboratory Validation of Chlorine Dioxide Decontamination  	105
Figure 5.1-3, Log of Colony Forming Units (cfus) Remaining at Each Time Point for Trial 5;
      Laboratory Validation of Chlorine Dioxide Decontamination  	106
Figure 5.1 -4. Log of Colony Forming Units (cfus) Remaining at Each Time Point for Trial 1;
      Laboratory Validation of Chlorine Dioxide Decontamination  	106
Figure 5.1-5. Log of Colony Forming Units (cfus) Remaining at Each Time Point for Trial 10;
      Laboratory Validation of Chlorine Dioxide Decontamination  	107
Figure 5.1-6. Chlorine Dioxide Generation System and Interior Operations	109
Figure 5.1-7. Beltsville Data for Bacillus subtilis spore strip analysis at various conditions .111
Figure 5.1-8. Beltsville Data for Bacillus stearothermophilus spore strip analysis	112
Figure 5.1-9. Bleaching Effect on Photographic Materials   	115
Figure 5.2-1. Chemical Reactions to Generate and Remove Hydrogen Peroxide from the Air 136
Figure 5.2-2. The Clarus C and Claris L Units for Hydrogen Peroxide Vapor Generation  ..  137
Figure 5.2-3. The Steris VHP 1000 Hydrogen peroxide vapor System   	137
Figure 5.2-4. Hydrogen Peroxide Vapor Concentration versus D-Value	140
Figure 5.2-5. Log of Colony Forming Units (cfus) Remaining at Each Time Point for Trial 6;
      Laboratory Validation of Hydrogen Peroxide Decontamination	143
Figure 5.3-1. Percent Survival of Test Organisms after Decontamination with Various
      Concentrations of Formaldehyde	154
Figure 5.3-2. Percent Survival of Test Organisms after Decontamination at Various Relative
      Humidities	155
Figure 5.3-3. Percent Survival of Test Organisms with Variation of Temperature During
      Decontamination with Parafornialdehyde at 10.5 G/m3 and a Relative Humidity of
      Approximately 58 Percent	155
Figure 5.4-1. Abstract of Scheffrahn and Weinberg Study   	172
Figure 5.4-2. Trailer configuration	172
Figure 5.4-3. Spore strip sites 1 and 2  	173
Figure 5.4-4. Spore strip site 13	173
Figure 5.4-5. Spore strip site 3  	174
Figure 5.4-6. The Prepared Trailer	174
Figure 5.4-7. Methyl Bromide Concentration During Trailer Fumigation and Aeration	175
Figure 5.4-8. Summary of IITRI Research Findings  	177
                                         vm

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                                 LIST OF TABLES

Table 1.3-1.  Summary Table of Applicable Technologies	4
Table 1.3-2.  Summary of Technology Application Issues	8
Table 1.4-1.  Potential Research Areas	10
Table 3.1-1.  Hypochlorite Decontaminants 	23
Table 3.1-2.  Residual Agent after Decontamination 	28
Table 3.2-1.  Deactivation ofListeria monocytogenes Using Chlorine Dioxide Solutions  .... 34
Table 3.2-2.  Effect of Adding Acid to Stabilized Chlorine Dioxide Solution	34
Table 3.2-3.  Effectiveness of Acidified Stabilized Chlorine Dioxide on Bacteria	35
Table 3.2-4.  Coliform Reduction in Drinking Water Treated with Chlorine Dioxide	35
Table 3.2-5.  Chlorine Dioxide Concentration for 5-log Reduction in
       Cell Count at 60 Seconds	36
Table 3.2-6.  Inactivation of Bacteria with Chlorine Dioxide	36
Table 3.2-7.  Mortality of Fungi After in vitro Contact with C1O2 at
       Various Concentrations and Contact Times 	:	38
Table 3.2-8.  C1O2 Control ofPoiiovirus I.  in Treated Sewage	39
Table 3.2-9.  C1O2 Bio-Fouling Control	 39
Table 3.3-1.  Reaction of Hydrogen Peroxide-Containing Solutions with Chemical Agents ... 46
Table 3.3-2.  Effect of pH on VX Detoxification Using Hydrogen Peroxide	47
Table 3.3-3.  Effectiveness of Hydrogen Peroxide and Catalysts on Chemical Agents	48
Table 3.3-4.  Reduction of Bacteria in Sponges Following Hydrogen Peroxide Treatment .... 49
Table 3.3-5.  Performance of Hydrogen Peroxide-Containing Formulation
       Sprayed Onto Glass Slides	50
Table 3.3-6.  Effectiveness of Hydrogen Peroxide on Biological Agents	51
Table 3.4-1.  Surface PCB Removal Based on Wipe Samples  	60
Table 3.4-2.  PCB Removal at Depth  Based on Corings	60
Table 3.4-3.  Gas Turbine Generator PCDD/PCDF Wipe Samples Before and After	 62
Table 4.1-1.  Summary Reaction Rates of Agent Simulant Testing 	70
Table 4.1-2.  Live agent kill rate summary (testing conducted at IIT Research Institute)  	70
Table 4.1-3.  B. globigii (Anthrax Simulant) Spore Kill During Dugway Filed Tests	71
Table 4.1-4.  Percent Decontamination in Live Agent Testes at ECBC	71
Table 4.1-5.  Modec Decon Foam against Toxic Industrial Chemicals 	72
Table 4.1-6.  Decontamination of CARC Panels8	74
Table 4.2-1.  Comparison of CASCAD to DS2 and C8	 82
Table 4.2-2.  CASCAD Effectiveness Against Chemical Warfare Agents   	83
Table 4.2-3.  Effectiveness of CASCAD Treatment	84
Table 4.3-1.  Surrogate Spore Counts Before and After L-Gel Treatment	92
Table 5.1-1.  Effect of C1O2 Gas Concentration on the Rate of Inactivation of 106
       B. subtilis Spores on Paper  Strips  	102
Table 5.1-2.  Vendors for C1O2	127
Table 5.2-1.  Effectiveness of Liquid  and Hydrogen Peroxide Vapor on Spores	139
Table 5.2.2.  D-Values  of Bacterial Spores Exposed'to Hydrogen Peroxide Vapor ;	140

                                                                          (continued)
                                         IX

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                            LIST OF TABLES (concluded)

Table 5.2-3.  Hydrogen Peroxide Vapor Efficacy at Various Temperatures
       against Geobacillus stearothermophilus spores  	141
Table 5.3-1.  Survival of Test Organisms on Strips Positioned at Different
       Test Locations During Decontamination	156
Table 5.3-2.  The Effects of Formaldehyde on Various Organisms  	157
Table 5.3-3.  Measured Average Conditions and Experimental Kill of B. Globigii	158
Table 5.3-4.  Paraformaldehyde Sterilization of Facilities, Materials, and Equipment	159
Table 5.3-5.  Percent Recovery of B. subtilis in Test Tubes with Paper Closures  	160
Table 5.3-6.  Percent Recovery of B. subtilis in Test Tubes with Glassine Closures	161-
Table 5.3-7.  Percent Recovery of B. subtilis in Test Tubes with Cotton Plug Closures 	161
Table 5.4-1.  Global Methyl Bromide Pre-Plant Soil Fumigation: Usage of
       Methyl Bromide for Pre-plant soil Applications by Country (1996)	169
Table 5.4-2.  Spore Germination After Methyl Bromide Exposure  	170
Table 5.4-3.  Germination of Spores After Exposure to,Methyl Bromide, Second Test	171
Table 5.4-4.  Spore Strip Location, Proximal Ambient Temperature Conditions, and
       Incubation Results for 80 Strips After Exposure for 48 Hours to Methyl Bromide
       at a Concentration of 303.7 oz/l,000ft3 in Trailer	176

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                              ACKNOWLEDGMENTS
       This report was initially compiled by R. Paul Schaudies, John B. Vierow, William Ellis,
Fred Myers, and Mary L. Wolfe from Science Applications International Corp. (SAIC) of
McLean, VA, through Work Assignment 1-31 issued under EPA Contract No. 68-C-02-067.
Sections describing the decontamination of Federal buildings following the 2001 anthrax mail
incident were prepared by D. Bruce Henschel, the former lead for the building decontamination
program within the National Homeland Security Research Center of EPA's Office of Research
and Development (ORD).  Mr. Henschel also provided substantial additional technical input and
technical editing in the finalization of this document, and served as a technical consultant during
SAIC's conduct of the Work Assignment.  Scott R. Hedges of the National Risk Management
Research Laboratory (NRMRL) in ORD served as the Work Assignment Manager.

       Special recognition is given to several individuals within EPA who provided detailed
technical reviews of the draft document, based upon their direct experience with the building
remediation activities that followed the October 2001 anthrax mail incident. These individuals
include: Carlton (Jeff) Kempter, in the Antimicrobials Division of EPA's Office of Pesticide
Programs; Dorothy A. Canter, in the Office of the Assistant Administrator for EPA's Office of
Solid Waste and Emergency Response; and G. Blair Martin, Associate Director of NRMRL's
Air Pollution Prevention and Control Division.
                                         XI

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              xu

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1.
EXECUTIVE SUMMARY
1.1    Objective

In September 2002, the U.S. Environmental Protection Agency (EPA) created the National
Homeland Security Research Center (NHSRC) within the Agency's Office of Research and
Development (ORD). As one of the elements within NHSRC, the Safe Buildings Team has, as a
key part of its responsibilities, engineering and economic analysis of alternative technologies and
approaches for decontaminating buildings following an attack using chemical and biological
(CB) agents. The ultimate objective of this decontamination program is to produce a rigorous
guidance document that can assist a range of users - including governmental agencies, building
owners and operators, and cleanup contractors - in most effectively selecting and implementing
the decontamination approach for any particular building following a CB attack.

As an initial step in this Safe Buildings decontamination program, NHSRC commissioned this
report, to provide background information regarding potential building decontamination
technologies. This state-of-the-art review of decontamination technologies is intended to: 1)
assist NHSRC in prioritizing the technologies to be evaluated under its decontamination
program; and 2) serve as an educational tool for the various NHSRC clients interested in
building decontamination.

1.2    Decontamination Technologies Addressed in this Document

This document presents an analysis of technologies that have been tested for their potential
effectiveness in decontaminating a building that has been attacked using biological or chemical
warfare agents, or using toxic industrial compounds. This document does not present an
exhaustive evaluation of all potential technologies.  Rather, the focus is on what are currently
felt to be the most promising technologies, based upon commercial use in related applications
(e.g., medical sterilization), and based upon their apparent potential for possible use in building
decontamination. The technologies presented in this document include:

      Hypochlorite
      Aqueous chlorine dioxide
      Aqueous hydrogen peroxide
      TechXtract®
      Sandia Foam and Decon Green
      CASCAD®
      L-Gel
      Chlorine dioxide gas
      Hydrogen peroxide vapor
      Paraformaldehyde
      Methyl bromide

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Before a chemical product intended for use in decontaminating biological agents may be sold or
distributed in the United States, EPA must either register that product as a pesticide under the
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), or, in the absence of registration,
must grant a crisis exemption allowing its use. Once registered or exempted for this use, the
pesticide would be commercially and legally available for use in accordance with the terms of
the registration or exemption. To date, EPA has not issued any registrations for decontamination
of biological threat agents in buildings, but has issued crisis exemptions that have permitted the
unregistered use of a number of liquid and gaseous and vapor products for the treatment of
Bacillus anthracis. EPA performed a full review of available data for each product along with
the remediation action plans for each site to ensure the product would be used safely and would
likely be effective against Bacillus anthracis.  A list of the crisis exemptions approved to date by
EPA is found at www.epatechbitorg under "Crisis Exemptions."

There are additional technologies that are in the pipeline that could be effective for building
remediation efforts. Because they are still under evaluation, these technologies are not addressed
in this report.  In addition, standard chemical spill technologies, such as the use of absorbents,
can be considered as well.  Prior to selecting the agent(s) judged to be most appropriate for
remediating a contaminated building, the user should consider the type and layout of the
contaminated building; the materials in the building; the nature and extent of the contamination;
the toxicily, penetrability, and materials compatibility of the potential agent(s); the aeration of
the agent and any other by-products produced during the clean-up; history of usage of the
agent(s); the time required to complete the remediation; and the cost of the overall process.

1.3    Summary of Technology Status

The technologies evaluated fall into three broad categories - liquids, foams  andgels, and gases
and vapors.  Each has advantages and disadvantages depending upon the type of contaminant,
the type of materials to be decontaminated, and the size of the remediation area. No single
technology is applicable in all situations; some technologies are better selections than others. As
a broad generality, liquids are effective cleaners of non-porous surfaces, but may cause corrosion
or degradation of the surface. Foams and gels have shown some promising results against both
biological and chemical  contaminants, but present post-decontamination cleanup issues, and
require further demonstration. Gases and vapors have been demonstrated to be effective in
destroying biological contamination under controlled conditions (e.g., in sterilization chambers),
but have not been effective in removing chemical contamination. There have been several
demonstrations of gaseous fumigants for the biological decontamination of portions (or the
entirety) of buildings under the less well controlled conditions that exist in the field, but further
field tests are required to demonstrate the practical engineering and economic applicability of
some of the fumigants.

Table 1.3-1 presents a summary of the technologies evaluated in this report, their technical
maturity (i.e., whether under development, demonstrated but not available, commercially
available, and whether approved by EPA for use as a pesticide), the type(s)  of contaminant to
which they are applicable, the types of building applications in which they can be  used, and a
summary of their effectiveness.  Within the context of this report, "commercially available"
indicates that the technology is available for purchase; however, as discussed above, if the

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technology is to be used to against biological agents, the technology would require EPA
approval for use as a pesticide.

Table 1.3-2 summarizes treatment issues to consider in selecting a technology, including
compatibility of the technology with typical building materials, a summary of the types of
residuals that will be generated from treatment, and information on performance of or need for
specialized hardware.

More detailed information on each technology can be found in Sections 3 through 5 of this
report.

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Table 1.3-1. Summary Table of Applicable Technologies
Technology

Hypochlorite









Aqueous chlorine
dioxide





,

Aqueous
hydrogen
peroxide










TechXtract




Sandia Foam and
Decon Green















Technical
Maturity
Mature,
commercially
available.







Mature,
commercially
available.






Mature,
commercially
available.










Innovative,
commercially
available.


Sandia Foam:
Commercially-
available, full
scale

Decon Green:
Not
commercially
available








Applicable Agents

Chemical agents:
(nerve and blister)
Biological agents
(Bacillus
anthracis)





Biological agents








Chemical agents:
(nerve and blister)
Biological agents










Toxic industrial
materials



Chemical agents:
(nerve and blister)
Biological agents
(Bacillus
anthracis)












Scope of Building
Applications
Treatment of
contaminated
surfaces in sites of
varying sizes.






Treatment of
contaminated
surfaces in sites of
varying sizes.





Treatment of
contaminated
surfaces in sites of
varying sizes.









Removal of organics
from porous materials
(e.g., concrete floors)
and from metal
equipment.
Limited: wall and
floor surfaces, small
areas, non-sensitive
equipment, personnel
protective equipment,
furnishings (non-
fabric)










Effectiveness

Reports state the
effectiveness on chemical
agents, but no data are
available. A 6 log kill of
Bacillus subtilis was
achieved on hard, non-
porous surface treated
with sodium hypochlorite
at pH 7 with a 60-minute
contact time.
EPA has data showing the
efficacy of 500 ppm
aqueous chlorine dioxide
on hard, non-porous
surfaces after 30 minute
contact time. EPA issued
a crisis exemption for
building surfaces on this
basis.
EPA reviewed data from
companies showing the
efficacy of one hydrogen
peroxide product and four
hydrogen peroxide &
peracetic acid mixture
products with contact
times ranging from 1 0 to
30 minutes. On the basis
of these data, EPA issued
crisis exemptions for the
use of these products on
building surfaces.
Greater than 99.93%
reduction in dioxin/furan
concentrations; variable
performance on removal
of PCBs from concrete.
Potentially effective
decontaminant for
chemical agents in
military and industrial
applications; easy to
apply. EPA issued a
FIFRA crisis exemption
for two foams derived
from the Sandia formula-
tion, but these were later
withdrawn when one of
the technologies failed to
pass EPA's AOAC
Sporicidal Activity Test.
EPA has not received or
reviewed data for Decon
Green under FIFRA.

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Technology

CASCAD









L-Gel





Chlorine dioxide
gas





















Technical
Maturity
Commercially
available.








Innovative.
Hearing
commercial-
ization.


Mature in a
range of
applications
(medical
sterilization,
water treatment,
oil well treat-
ment).
Commercially
available.













Applicable Agents

Chemical agents:
(nerve and blister)
Biological agents
(Bacillus
anthracis)
Radiological
containment



Chemical agents:
(nerve and blister)
Biological agents
(Bacillus
anthracis)

Biological agents
(Bacillus
anthracis)




















Scope of Building
Applications
Product is not
demonstrated in
buildings but foam-
based application to
surfaces and walls is
possible.




Gel form will adhere
to vertical and
overhead surfaces.
Penetrates paint and
varnish.

Used to fumigate
three sites, ranging in
volume from 90,000
to 14 million cubic
feet, contaminated
with B. anthracis.
Need to achieve
proper ranges of
temperature, relative
humidity, concentra-
tion and exposure
duration to achieve
effective kill rates.
Must be able to seal
area completely.








Effectiveness

Vendor claims removal of
nerve agents within five
minutes of application.
US test data show
variability in treatment
effectiveness that requires
additional study. EPA has
not received or reviewed
data for CASCAD under
FIFRA.
Research shows more
than 99 percent effective
for all agents on all
surfaces. EPA has not
received or reviewed data
for L-Gel under FIFRA.
Data show six log kill in a
reproducible fashion on
specific surfaces under
controlled conditions in
test chambers or bio-
medical sterilization units.
Highly effective in
reducing B. anthracis
spore load in Hart Senate
Office Building, though
further surface treatment
with liquid agent needed.
In combination with other
decon steps, successful in
remediating the
Brentwood (Washington,
DC) postal facility, since
all post-remediation
environmental samples
were negative. Along
with other steps, also
successful at the Trenton,
NJ, postal facility.

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Technology
Hydrogen
peroxide vapor























Technical
Maturity
Mature in
pharmaceutical
applications.
Commercially
available.




















Applicable Agents
Biological agents
























Scope of Building
Applications
Used in pharmaceuti-
cal industry to treat
manufacturing clean
rooms and laboratory
animal toxicology
rooms. Used to
fumigate two federal
mail facilities, with
volumes of 1 .4 to 1 .7
million cubic feet,
contaminated with B.
anthracis spores.
Both buildings were
sub-divided into
zones no greater than
250,000 cubic feet
each. Zones were
fumigated
sequentially.
Hydrogen peroxide
vapor interacts with
nylon and with
porous surfaces,
thereby losing
effectiveness.
Effectiveness
Documented effectiveness
against viruses, bacteria,
and spores under
controlled conditions.
Achieved log six kill on
all B. stearothermophilus
biological indicators in all
zones fumigated at GSA
Building 410 and at the
Dept of State mail annex
SA-32. Special effort
required to maintain HjO2
concentration in SA-32
due to porous surfaces
(e.g., unpainted concrete
block) in the building.










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Technology

Paraformaldehyde


































Methyl bromide













Technical
Maturity
Mature in
biomedical lab
applications.
Commercially
available.






























Innovative in
this application.
Commercially
available for
residential,
agricultural pest
control applica-
tions.






Applicable Agents

Biological agents


































Biological agents.
(Has historically
been applied for
insects.)










Scope of Building
Applications
Used to decontamin-
ate labs and biosafety
hoods for range of
bio agents, including
B. anthracis. Follow-
ing 2001 B, anthracis
mail attack, was used
successfully in Dept.
of Justice mail
facility to treat mail
sorting equipment
enclosed within a
tented volume.
Utilized by US Army
Medical Research
Institute of Infectious
Diseases
(USAMRIID)to
decontaminate entire
buildings with high
levels of B. anlhracis
contamination. Has
good penetrability of
surfaces. The
fumigant (which is a
Hazardous Air
Pollutant) -and the
byproducts from
reaction of the
fumigant with
organic compounds
on surfaces - might
de-gas from porous
surfaces over a period
of time.
Testing in a mobile
home showed ability
to kill spores in the
Bacillus family in
difficult-to-reach
areas. A concern is
that methyl bromide
is an ozone depleter,
and no effective
system has yet been
demonstrated for
destroying the fumi-
gant following
fumigation.
Effectiveness

Proven effectiveness in
multiple settings,
including labs, isolated
volumes within buildings,
and,inUSAMRIID's
case, entire buildings.
USAMRJID regulations
for fumigations of articles
and areas within buildings
stipulates that spore strips
containing 10s spores of
B. stearothermophilus and
additional spore strips
containing 106 spores of
B. subtilis var. niger all be
negative for growth of the
spores after fumigation;
otherwise the fumigation
is to be repeated.
















In a test trailer, achieved
6-log kill of B. anthracis
surrogates in hard-to-
reach locations following
a two-day fumigation.










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Table 1.3-2. Summary of Technology Application Issues
Technology
Hypochlorite
Aqueous chlorine dioxide
Aqueous hydrogen
peroxide
TechXtract
Sandia Foam and Decon
Green
CASCAD
L-Gel
Chlorine dioxide gas
Materials Compatibility
Not compatible with
dyes. Corrosive. Oxidant.
Harmful to fabrics
(oxidant)
Harmful to fabrics
(oxidant)
Abrades or dissolves
away treated porous
surface.
Bare steel objects are
susceptible to rust after
application. Safe on all
other surfaces, according
to the vendor.
. No effect on paint,
rubber, or aluminum,
according to the vendor.
No harm to carpet or
paint, according to the
developer.
Bleaching of selected
fabrics and photographic
materials.
Residuals/ Degradation
Products
Corrosive nature of
material means that waste
products should be
managed and disposed of
as hazardous waste.
Excess aqueous solution
is an oxidant. If gas is
generated on-site to
produce the solution,
byproducts of the
generation process can
include a brine solution,
depending on the process.
None. Breaks down to
water and oxygen after
treatment.
Fresh TechXtract solution
is not hazardous,
according to the vendor.
Waste extract generated
by the use of the product
may contain hazardous
chemicals.
Foam requires removal
and may be contaminated
with removed chemicals.
Foam requires removal
and may be contaminated
with removed chemicals.
Silica in gelling material
considerably increases the
amount of waste requiring
management.
Wastes will include: a)
wastes from generation of
the C1OZ (e.g., a brine
solution, depending upon
the C1O2 vendor); and b)
wastes from scrubbing the
ClOj from the fumigated
area prior to aeration
(e.g., a caustic sulfite/
sulfate solution).
Additional Hardware
Requirements
Not applicable.
Commercial aqueous
C1O2 products can be
imported from off-site,
requiring no additional
hardware on-site.
Alternatively, aqueous
ClOj can be produced by
solubilizing CIO, gas
manufactured on-site
using on-site generators.
Not applicable.
No data.
Uses standard,
commercially available
paint sprayers.
Uses standard firehoses.
A backpack version also
can be purchased from
the vendor.
Uses standard,
commercially available
paint sprayers. Must use
a metal nozzle due to
corrosivity of L-Gel.
Gas is unstable and
cannot be stored in
canisters. A specialized,
potentially sophisticated
gas generation system is
required, which will vary
depending upon the C1O2
vendor. A system will
also be required for
scrubbing the residual
C1O2 from the building air
following fumigation.

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Technology
Hydrogen peroxide vapor
Parafonnaldehyde
Methyl bromide
Materials Compatibility
Not corrosive, but will
discolor dyes and have
unfavorable interactions
with nylon. Porous
surfaces may degrade and
inactivate hydrogen
peroxide vapor.
No problems reported.
No damage to
photographic, cellulosic,
fabric, or electronic
materials in two
experiments in a trailer.
Residuals/ Degradation
Products
None. Vapor
introduced/withdrawn
from site in closed system
containing a catalyst on
the return side which
degrades hydrogen
peroxide vapor to water
and oxygen.
Following fumigation, the
formaldehyde (a
Hazardous Air Pollutant)
is scrubbed from the
treated area using, e.g.,
ammonium bicarbonate
prior to aeration.
Byproducts from this
scrubbing process will be
a waste.
After treatment, the
methyl bromide must be
scrubbed from the treated
area, and there will likely
be wastes from this
scrubbing process.
Byproducts from this
scrubbing process will be
a waste. Currently, there
is no treatment to destroy
methyl bromide following
fumigation; in the
experiments performed to
date, it has been released
directly to the
environment.
Additional Hardware
Requirements
Hydrogen peroxide vapor
is produced by heating a
35% solution of hydrogen
peroxide.
p-Formaldehyde can be
heated on hotplates using
disposable pie tins or by
using a generator system.
Liquid under pressure is
heated on-site to create
vapors that are pumped
into the space to be
fumigated.
1.4    Identification of Areas for Potential Research
Table 1.4-1 presents the areas of potential future research identified for each technology as well
as those applicable to all.

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Table 1.4-1. Potential Research Areas
Technology
Hypochlorite
Aqueous hydrogen
peroxide
Aqueous chlorine
dioxide
TechXtract
Sandia Foam/ Decon
Green
CASCAD
L-Gel
Chlorine dioxide gas
Hydrogen peroxide
vapor
Paraformaldehyde
Methyl bromide
Other
Research Areas
• At what concentration, pH, contact time, or other parameters would
hypochlorite be effective on porous surfaces.?
• At what concentration, pH, contact time, or other parameters would
hypochlorite be effective on biological agents other than anthrax spores?
• Field testing is needed to determine treatment effectiveness and operational
variables (e.g., contact time, concentration) towards both chemical and
biological agents.
• Field testing is needed to determine treatment effectiveness and operational
variables (e.g., contact time, concentration) towards both chemical and
biological agents.
• Laboratory and field testing of the technology is needed, including destruction
effectiveness, against chemical warfare agents such as VX and GB.
• Testing is needed of treatment effectiveness on nonporous surfaces.
• Field tests are needed to demonstrate the effectiveness of the technology and the
stability of hydrogen peroxide in "dirty" environments.
• Independent verification of manufacturer' s claims is needed.
• Validation is needed of use for initial isolation of contamination.
• Verification is required of pending improvements to increase penetration into
porous surfaces and to aerosolize L-Gel for application to interior ventilation
systems.
• Mechanisms must be studied to minimize the mass of amorphous silica used.
• Potential for stabilization of waste materials must be studied.
• Further research is needed to determine D-values for C1O2 concentrations in
range (750 - 2000 ppm) used for fumigations of three contaminated facilities
• Reliable, rugged, and cost effective real-time monitors for C102 concentration
must be developed in the concentration range used for fumigations
• Research is necessary on effectiveness against other biological agents.
• Research is needed on effectiveness against chemical agents.
• Research is needed on materials in buildings which absorb and/or react with
vapor, decreasing effective concentration in space being fumigated.
• Research is needed to develop an improved system for vapor generation
• Feasibility of scaling up technology to fumigate spaces larger than 200,000
cubic feet must be demonstrated.
• The optimal combination of vapor concentration, relative humidity, temperature,
and contact time needed to achieve effective decontamination must be determined.
• Quantification is needed of the effectiveness of treatment on porous surfaces and
difficult to reach areas.
• More extensive research is needed on critical process parameters for effective
spore kill; namely, temperature, relative humidity, vapor concentration,
exposure time.
• A practical system to destroy methyl bromide vapor following fumigation must
be demonstrated, so as not to release it to the environment
• A standardized method must be developed for preparation of bacterial and viral
standards for remedial technology validation.
• Effectiveness of using combinations of technologies (i.e., different gas phase
technologies) as a treatment train should be studied.
                 10

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1.5    The NHSRC Decontamination Program to Address these Issues

The NHSRC Safe Buildings decontamination program, designed to address the issues raised
above, to the extent possible, is formulated as follows.

"Lessons Learned". Extensive practical experience in building decontamination has been
developed during the course of the building remediations that followed the 2001 anthrax mail
attacks. Under the Safe Buildings program, NHSRC will interact with all of the principals
involved in these remediations, compiling the data that were generated and documenting the
practical field experience that was gained. This will enable NHSRC to provide decontamination
guidance to future users mat draws, as fully as possible, on the past experiences.

"Systematic Decon".  In a series of controlled experiments, NHSRC will determine how the
performance of alternative decon technologies - liquids, foams and gels, and gases and vapors -
vary as key parameters are varied. The parameters that will be varied include, e.g., the nature of
the CB agent, the substrate on which the agent is deposited (wallboard, carpeting, etc.), the
concentration of the decon agent, the exposure time, the temperature, and the relative humidity.
Performance measures will include the efficacy of killing biological agents or neutralizing
chemical agents, compatibility of the decon agent  with the substrate, and residual  degradation
products left on the decontaminated surface. The results from these experiments will address
many of the questions raised in Table 1.4-1, regarding the effectiveness  of these decon agents
under various conditions.

Decon Environmental Technology Verification  (ETV\ NHSRC has established a Decon ETV   -
program, under which vendors of decontamination technologies can submit their technologies
for independent testing by EPA under a standardized protocol. The results from this ETV testing
will provide EPA and potential users with an increased, independent database on the
performance of these technologies.

Engineering and Economic Analysis.  Drawing  from the above three projects, a parametric
analysis will be conducted of the practical engineering issues that will have to be addressed, and
the cost-effectiveness of the remediation, for alternative decontamination approaches.  The
parameters that will be addressed will include the nature of the CB attack, key variables defining
the building, and key variables associated with each step of the overall remediation process. The
results will be reviewed to determine whether preferred remediation approaches become
apparent for particular building characteristics and attack scenarios.

Decon Technical Guidance Document.  The results from all of the tasks above will be brought
together in the development of a user-oriented technical guidance document for building
decontamination. This document would assist building owners and operators, governmental
agencies, remediation personnel, and others in the cost-effective selection and implementation of
remedial action steps in the event of a CB attack on a large building.  Once the user has defined
the characteristics of the building and the extent and nature of the attack, the guidance document
would suggest, for example: the extent, methods, and cost of sealing the "hot zone"; the extent
(and costs) of removal of interior furnishings for disposal, prior to further building treatment; the
nature and extent of interior decon (with HEP A vac and liquid agents) prior to fumigation, and
the associated costs; fumigation methods, and cost-effective operating conditions; and the nature
and amounts of wastes requiring disposal.
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               12

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2.
INTRODUCTION
2.1    Scope, Purpose, and Summary

Following the events of September and October, 2001, there is increased concern regarding the
possibility of the deliberate introduction of chemical or biological (CB) agents, toxic industrial
chemicals (TlCs), or toxic industrial materials (TIMs) into buildings by terrorists.  Such an
attack would require effective and prompt efforts to protect building occupants and to
decontaminate the building for re-occupancy. Work on decontamination following CB attacks
has been underway at the Department of Defense (DoD) and other agencies for many years,
often focused on military applications.

On September 24,2002, the EPA Administrator announced the formation of EPA's National
Homeland Security Research Center, headquartered in Cincinnati, Ohio.  The Center, as part of
the Office of Research and Development (ORD), manages, coordinates, and supports a wide
variety of homeland security research and technical assistance efforts.  Research at the Center
will focus on developing methods to: 1) protect building occupants during a CB attack, and to
decontaminate contaminated buildings following the attack (including proper disposal of
contaminated waste materials); 2) protect the nation's drinking water supply; and 3) improve risk
assessment techniques. Research on homeland security will develop the scientific foundations to
provide decision-makers with increased understanding and tools necessary to prevent or manage
a range of potential treats.

This document is intended provide background information on potential post-attack building
decontamination technologies, as an aid to EPA in planning their program and as an educational
tool for other users. The document critically analyzes the general knowledge and primary
references regarding commercial and near commercial technologies for decontamination of
surfaces contaminated with CB agents, TICs, and TIMs. This document is intended for
educational purposes. As such, it provides an overview of selected technologies, discusses the
available data and efficacy, and highlights potential research needs.

2.2    Summary of Decontamination Technologies Selected for Evaluation

The starting point for identification of technologies was the Review of Decontamination
Technologies for Biological and Chemical Warfare Agents (Mitretek, 2003) prepared by
Mitretek for EPA, which provided an overview of potential remediation technologies and
included a literature review. Other primary sources consulted were the DoD Wide Area
Decontamination Study (Battelle, 1999), materials from the EPA Technology Innovation Office
(TIO), and other readily available references. A list of potential technologies, shown below, was
developed.
Surface-Applied Technologies
       Hypochlorite
       Aqueous hydrogen peroxide
       Aqueous chlorine dioxide
       HPO2® (enhanced aqueous H2O2)
       Decontaminating Solution 2 (DS2)
       TechXtract®
       Nanoemulsions
                                              Enzymes
                                              Sandia Foam and Decon Green
                                              CASCAD®
                                              L-Gel
                                          13

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Gas- and Vapor-Phase Technologies
•      Ethylene oxide
•      Chlorine dioxide gas
•      Hydrogen peroxide vapor
•      Paraformaldehyde
•      Ozone
•      Methyl bromide

Other Technologies
•      Directed energy
•      Photochemical
•      Plasma
A brief synopsis of the potential for use of the technology in a building remediation application
was drafted and formed the basis for determining the technologies to be included in this
document  A summary of the determination on each technology is presented below.
         i
2.2.1   Surface-Applied Technologies Considered

Surface applied technologies include liquids and foams or gels.  Liquid technologies involve the
application of liquid decontamination solutions directly on a surface contaminated with a
biological or chemical agent. Eight technologies are evaluated in this category - hypochlorite
(e.g., bleach), aqueous hydrogen peroxide, aqueous chlorine dioxide, HPO2, DS2, a proprietary
technology called TechXtract, and nanoemulsions.  With these technologies, the solution is
applied to the surface of the material to be decontaminated. The solution is removed by wiping
or wet vacuuming.

Foam and gel technologies are designed to enhance surface removal of biological or chemical
contaminants by delivering the decontamination formulation in a matrix that can be applied to
vertical and horizontal surfaces. This allows the application to walls with sufficient contact time
to ensure that the CB agent is effectively treated. In this category, three technologies are
evaluated - Sandia Foam and Decon Green, CASCAD, and L-Gel.

Hypochlorite:  Historically, chlorine-based decontamination systems have been effectively
employed against chemical and biological agents. The use of hypochlorite solutions (aqueous
and non-aqueous) or solid/slurry hypochlorites has been wide spread for military applications.
Hypochlorite is a standard decontaminant in military applications, excluding shipboard use.
This general purpose decontaminant has been used on personnel, equipment, clothing, building
surfaces, and soil.  It is relatively easy to obtain and inexpensive.  While an effective
decontaminant, it is corrosive, can form toxic by-products, and has irritant properties that are
undesirable. The military typically uses HTH (high test hypochlorite) and STB (super  topical
bleach), along with household bleach solutions, for agent spills and personnel  decontamination.
In addition, EPA evaluated data on one hydrogen peroxide and four hydrogen peroxide/peracetic
acid mixtures. Based on efficacy at contact times ranging from 10 to 30 minutes, EPA issued a
crisis exemption for the use of these products on building surfaces.  Because of the wide
                                           14

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experience in its application and its commercial availability, .this technology was further
evaluated in this report.

Aqueous hydrogen peroxide:  There are several sterilization products on the market which
contain hydrogen peroxide.  These have applications in the food and medical industries for
general hard surface cleaning of biological organisms as well as food preparation. Additionally,
there are specialized formulations available which have been developed specifically for building
or warfare decontamination. Because of the potential for application to building decontamina-
tion, this technology is evaluated further in this report.

Aqueous chlorine dioxide:  As a biological sterilizer, chlorine dioxide (C1O2) is an oxidant for
biological organisms and the exact method of destruction is not known. Unlike Chlorine (Cy,
chlorine dioxide is a single-electron transfer-oxidizing agent and does not react with organics to
form harmful chlorinated products such as trihalomethane and chloramines. Chlorine dioxide
has extensive use in drinking water treatment, generated from sodium chlorite and fed into the
water.  Sodium chlorite-based cleaners  are used in the food processing industry for cleaning of
surfaces and of food itself.  EPA has data showing the efficacy  of aqueous chlorine dioxide
against Bacillus spores on hard, non-porous surfaces when applied at a concentration of 500 ppm
for a 30-minute contact time. A crisis exemption for use of this agent against B. anthracis on
building surfaces was issued by EPA on the basis of these data. This technology has the
potential for application in buildings and is commercially available. As a result, it is further
evaluated in this document.

HPO2®:  EAI Corporation patented a variation of the aqueous hydrogen peroxide system called.
HPO2, in which hydrogen peroxide is added to Oxone®. The technology is reported to work for
bulk treatment of chemical agents. Variants of hydrogen peroxide have promise, but no data
could be located on this technology.  Further, its commercial availability is unknown. As a
result, this technology was not addressed in this report.

DS2: DS2 is recognized as the military bench mark for effective chemical and biological
decontamination.  DS2 was developed to destroy VX and reacts with G agents and mustard gas
at ambient temperatures.  It is a mixture of 70 percent diethylenetriamine (DETA), 28 percent
ethylene glycol monomethyl ether (also known as 2-methoxyethanol), and two percent sodium
hydroxide (NaOH).  The sodium hydroxide reacts with 2-methoxyethanol to form ethoxide. As
DETA is added, free sodium radicals are bound in the mixture.  DS2 is highly reactive, yet stable
in storage under a broad range of temperatures and times. DS2 is no longer manufactured and is
not used at chemical agent destruction facilities because of its corrosive nature to rubber, paint
and plastics and its environmental effects. Sorbents, enzymatic foams, other foams, oxidative
and reactive formulations, and BX24 (a powder that is mixed with water) are under investigation
as replacements. Because replacements for DS2 are being actively investigated and DS2 is
recognized to have corrosive properties, it was not evaluated in this report.

TechXtract®: TechXtract is designed to remove organics, heavy metals and radionuclides from
the surface and subsurface of porous and nonporous solid materials such as concrete,
brick, wood, and steel. Active Environmental Technologies, Inc. calls TechXtract a
"contaminant extraction technology." The technology uses proprietary chemical mixtures to
treat surfaces including floors, walls, ceilings, and equipment.  The mixtures may include macro-

                                          15

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and micro-emulsifiers, buffered organic and inorganic acids, and hydrotropic, electrolyte,
flotation, wetting, and sequestering agents that extract the contaminants and bring them to the
surface. The chemical mixtures are applied sequentially, in successive cycles.  Each treatment
cycle includes application, penetration, and extraction.  Wet vacuuming is used to remove the
solutions from the treated substrate. This low-tech, but innovative, aspect of the technology is
an important element of its effectiveness for porous substrates.  Effective decontamination of a
porous surface will be one of the more challenging aspects of building decontamination.
TechXtract is effective for porous surface decontamination because wetting agents are used to
increase permeation into pores and wet vacuuming is used to get treatment solutions back out of
pores.  While effective on porous surfaces, some abrasion or dissolution of the surface occurs.
The proprietary mixtures may include fluorides or other chemicals that present worker health
and safety issues.  Because TechXtract was tested and demonstrated in hazardous waste building
remediation, it was selected for further evaluation in this document.

Nanoemulsions:  A generic nanotech emulsion is a mixture of detergent, buffer,  oil and water.
The combination is emulsified and stable for many months. This material is not toxic and can be
applied to personnel as well as equipment.  Current applications require manual application, but
the technology could be modified for spraying for wide application. Nanotech emulsions are
reported to be effective against both chemical and biological agents.  Nanotech technologies
under development include a line of virus and pathogen Nanofilters® developed by US Global
Nanospace for use in aircraft and buildings. However, nanotech emulsions are in the early
development stages with additional research still underway. While the technology shows
promise, its near term applications are limited, and it was not evaluated for building remediation
applications.

Enzymes:  Enzymatic systems are reported to have been developed and tested successfully
against chemical agents. Researchers at Edgewood Chemical Biological Center are actively
engaged in these efforts. They identified and characterized enzymes that are effective against
chemical and biological agents and cloned the enzymes' genes. These enzymes decontaminate
chemical and biological agents through catalysis. The researchers developed a powder form of
the enzymes that requires the addition of water for decontamination.  The powders are designed
to attack specific contaminants, such as VX and mustard gas. This technology shows promise
but is at the research stage. At the current time, little data on these systems with respect to
building decontamination are available; additional information would be needed to consider this
emerging technology. Further, the technology is not yet in commercial production.  As a result,
this technology was not addressed in this report.

Sandia Foam/Decon Green:  Peroxide-based systems are one of the more visible chemical
agent decontamination systems in the market today.  Sandia National Laboratories developed
"Sandia Foam," which is marketed under the trade names EasyDecon® and Modec Decon
Formula (MDF) 200®. The Sandia foam uses a combination of surfactants and oxidizers to
inactivate both biological and chemical agents. Edgewood Chemical Biological Center patented
a similar system called Decon Green.  These systems are claimed to be effective against all
chemical agents, be easily applied, and not produce toxic residues or byproducts. Both Sandia
and the West Desert Test Center at Dugway Proving Ground have reported six-log kills of
Bacillus anthracis spores within one hour. EPA issued a crisis exemption for the use of these
foams in building remediation for B. anthracis. These were later withdrawn when, in separate

                                          16

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testing conducted by EPA under the Federal Insecticide, Fungicide, and Rodenticide Act
(FIFRA), one of the foams did not pass testing to be listed as a sterilizing agent for B. anthracis.
Because these technologies have potential, they were selected for further evaluation in this
document.

CASCAD®: The Canadian Aqueous System for Chemical Agent Decontamination (CASCAD)
is a chlorine-based system that delivers an aqueous foam designed to contain and eliminate
chemical and biological warfare agents and remove radioactive particle contamination. The
immediate isolation and containment of the contamination is its most significant advantage. The
active decontaminating ingredient is sodium dichloroisocyanurate (fichlor). Fichlor is used
extensively in the food and beverage industry as antibacterial detergent. CASCAD has been
tested in Canada, the U.S., and the U.K.  For surface decontamination, the biodegradable foam is
easily applied and sticks to vertical surfaces.  CASCAD is intended for exterior applications on
tanks and military equipment.  Its  use on building interiors has not been tested. Because there is
a body of data on decontamination of biological agents, CASCAD is being evaluated as a
building remediation alternative.

L-Gel: Lawrence Livermore National Laboratories has developed the L-Gel system using
Oxone®, with fumed silica as a gelling agent. Oxone is a non-chlorine  alternative used as a
decolorizer and disinfectant. The  active ingredient in Oxone is potassium peroxy monosulfate,
KHSO5. Similar in formulation to the Sandia Foam, this material combines oxidants with
surfactants to destroy biologicals by disrupting the lipid component. Oxone has been shown to
effectively react with chemical agents. Mechanisms for inactivation of chemical agents are less
well known, but the compound is  effective against both classes of agents. L-Gel can penetrate
polymeric coatings such as paint and varnish.  It is relatively inexpensive (about $1 for materials
only to treat 1 square meter). However, L-Gel is not commercially available (although licensing
discussions are underway). Additionally, the silica gelling agent increases the amount of waste
requiring management after remediation.  However, because of its potential applicability to both
chemical and biological agents and its near-term commercial production status, this technology
is further evaluated in this report.

2.2.2 Gas- and Vapor-Phase Technologies Considered

Gas and vapor phase technologies require that the area to be contaminated be completely sealed
to prevent the escape of the gas or vapor.  This may require  tenting the entire structure, or
comprehensive sealing of shell openings throughout the entire building (or in a particular zone
that is to be treated within a larger building). The gas or vapor is injected into the sealed area
and allowed to remain in place for the period of time required to ensure treatment. Gas and
vapor technologies are more susceptible to variations in temperature and humidity than liquid
and foam and gel technologies. Therefore, ways to control these variables must be considered.
Five gas and vapor phase technologies were considered - ethylene oxide, gaseous chlorine
dioxide, hydrogen peroxide vapor, paraformaldehyde, ozone, and methyl bromide.

Ethylene oxide: Ethylene oxide,  an odorless gas at room temperature, can be used for in several
applications, including walk-in sized chambers.  It is widely used in hospital and biomedical
sterilization applications because  it is highly penetrating. Off-site ethylene oxide chambers were
used for the successful sterilization of critical items for re-use, during anthrax remediation

                                           17

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efforts on Capitol Hill and in other federal mail facilities as well as at the National Broadcasting
System (NBC) offices in New York City. Ethylene oxide is a highly reactive molecule with
vapors that are flammable and explosive. As little as three percent ethylene oxide in air can be
flammable (NIOSH, 1994).  Toxicity data indicate that ethylene oxide is irritating to the skin,
eyes, and mucous membranes of respiratory tract  Toxicity data indicate that acute exposure to
ethylene oxide can cause nausea, vomiting, and death.  Chronic exposure can cause irritation of
eyes, skin, and mucous membranes, cataracts, and problems in brain function. Exposure to
ethylene oxide may result in lung, liver, and kidney damage (U.S. Department of Health and
Human Services, 1993).  Ethylene oxide is rated as a Group Bl (probable) human carcinogen.
Health concerns for subsequent off gassing resulted in an additional heating step to aid in the
release of ethylene oxide from the critical items treated during the remediation efforts in
Washington, D.C. and New York City. Due to the human health issues and the flammability of
ethylene oxide - limiting its use to carefully controlled chambers - this technology is felt to have
no applicability for the fumigation of buildings, other than possible use off-site for sterilization
of critical items.  Hence, it was not evaluated in this study.

Chlorine dioxide gas: Chlorine dioxide was discussed earlier under surface applied (aqueous)
technologies. Here, chlorine dioxide is considered in its gaseous form.  The chlorine dioxide gas
must be generated on site where remediation occurs using commercially available generators due
to the instability of the gas.  Gas replacement during remediation is required due to the
instability.  However, this instability has a benefit in that the gas rapidly decomposes after
treatment.  The gas has better penetrability than hydrogen peroxide vapor, and thus may more
likely be effective on porous surfaces, although this has yet to be demonstrated. Temperature
and humidity need to be controlled; effective performance may be very difficult to achieve if the
relative humidity drops below 60%.  Because this technology was employed successfully for the
remediation of the Hart Senate Office Building and the Brentwood (Washington, D.C.) and
Trenton, New Jersey, U.S. Postal Facilities, it is further evaluated in this report.

Hydrogen peroxide vapor: Hydrogen peroxide vapor is used to treat pharmaceutical
manufacturing clean rooms  and laboratory toxicology rooms. Hydrogen peroxide vapor was
used in the remediation of two federal mail facilities following the 2001 incident. It was
demonstrated to be effective against Bacillus spores, including the anthracis strain. This
technology is mature and commercially available. Because of its use in building remediation,
this technology is further evaluated in this report.

Paraformaldehyde: Paraformaldehyde is used for routine decontamination of labs and
biosafety hoods in clinical and research laboratories for a broad spectrum of biological agents,
including Bacillus anthracis spores. Paraformaldehyde is heated to generate formaldehyde gas
for use as a sterilizing agent. This gas has been used by the U.S. military  for the successful
remediation of numerous laboratories and buildings. Formaldehyde is an animal carcinogen and
probable human carcinogen, and it is genotoxic in a number of assays.  This technology is
mature and commercially available.  Because it has been used by the U.S. Army Medical
Research Institute of Infectious Diseases to decontaminate buildings, and was used for treating a
mail processing machine in the Department of Justice mail room following the 2001 B. anthracis
mail attacks,  it is further evaluated in this report.
                                           18

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Ozone: Ozone is a reactive form of oxygen that is a strong oxidant with documented ability to
kill spores, bacteria and viruses. Ozone generation systems are commercially available.
However, ozone has not been used for remediation of buildings. While this technology is
promising and could be considered for further evaluation in the future, it is not further evaluated
in this report.

Methyl bromide: Methyl bromide is approved for use as a pesticide under controlled
conditions. Its most common use is to kill termites in buildings, and in soil treatment for
agricultural pest control. Recent demonstrations show its potential for killing Bacillus spores.
As a result, the technology is further evaluated in this report.  However, methyl bromide is an
ozone-depleting compound. In addition, it has potential human health effects.  It has cumulative,
delayed effects on the central nervous system, which may appear as long as several months after
exposure. High concentrations can produce fatal pulmonary edema. Chronic exposure can
cause central nervous system depression and kidney injury. It may cause severe and permanent
brain damage.  Severe neurological signs may appear when there is a sudden exposure to high
concentrations following continuous slight exposure. Methyl  bromide has practically no odor or
irritating effects and therefore no warning, even at hazardous concentrations (EPA, 2003).

2.2.3  Other Technologies Considered

Directed energy alternatives:  Directed energy methods for decontamination, such as electron
beam, x-ray, gamma ray, ultra violet radiation, and microwave radiation, have all been
demonstrated to disinfect surfaces. As energy transfer methods, all of these systems can kill
bacteria, bacterial spores, and viruses, given sufficient time and power. .However, their use for
building remediation is questionable. While technically possible, it is probably not reasonably
feasible. Two  of the major concerns are shadowing and control of the directed energy.
Contamination within a building will most likely spread to multiple surfaces, many of which
might not be easily accessible to directed energy approaches.  While penetrating energy such as
electron beam, gamma, and x-rays might overcome many of the shielding issues, their cost and
secondary damage when applied to buildings could make them undesirable alternatives. As such
these technical alternatives were not reviewed in this document.

Photochemical: Clean Earth Technologies, LLC,  located in St. Louis, MO, has developed the
Electrostatic Decontamination System (EDS) for the Technical Support Working Group
(TSWG).  Their two step process works on both biological and chemical agents.  The EDS is
configured with a photosensitizer sprayer unit (pressurized or  battery powered), a photosensitizer
(PS) storage unit, and a light source unit (210-310 nm UV light source) for activation. The unit
weighs under 50 pounds and is contained on a cart for portability.  Clean Earth Technologies
claims the system is effective at rapidly neutralizing chemical agents and toxic industrial
chemicals (TICs) to levels below their Immediately Dangerous to Life and Health (IDLH)
concentrations, as well as disinfecting biological agents. The  photosensitizer is sprayed onto the
surface from a distance of 24 inches, and the UV light can reportedly then decontaminate
approximately 1,000 square feet of surface area in  15 minutes. The system has been tested on
vertical, horizontal, porous, and non-porous surfaces. The photosensitizer solution is claimed
have a shelf life of 10 years and is non-corrosive. This technology is still subject to research and
is not commercially available.  As a result, this technology was not further evaluated in mis
report.

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Plasma:  Plasmas can be generated at atmospheric pressures for the destruction of biological
organisms.  By passing energy through air, the molecules are ionized generating both positively
and negatively charged reactive species.  The interaction of these ions, along with the associated
ultraviolet light, kills the microorganisms.  This technique is applicable to the cleaning, and
perhaps disinfection, of small areas and electronic equipment. Because of the relatively labor
intensive method of employment and its  questionable activity on spores, it was not considered as
a candidate for technical evaluation for building remediation alternatives.

Physical Technologies:  There are time-tested, proven technologies for physical remediation of
chemical spills.  For example, there are a variety of sorbent materials (simple, reactive and
catalytic) on the market for spot surface  decontamination. However, after use, the contaminated
sorbent must be recovered and removed  for treatment. Hot air and steam jet systems can also be
considered as physical removal systems  for chemical threat agents.  But the chemical agent that
is thus driven from the surface must be collected and subsequently treated. This report does not
cover the standard spill remediation solutions that a responder may need to include in a
remediation effort. At sufficient temperature and exposure time, heat and steam have long been
utilized for killing biological organisms; however, the temperatures involved are probably too
high for practical use in a building. These technologies  are not evaluated here.

2.3    Broad Review of Categories of Alternatives with Potential Applications

Based on the comparative analysis described in Section  2.1, eleven technologies were selected
for analysis. The technologies presented in this document include:
                                               Foam/gel systems
                                               •      Sandia Foam and Decon Green
                                                      CASCAD
                                                      L-Gel
Liquid systems
•      Hypochlorite
•      Aqueous chlorine dioxide
•      Aqueous hydrogen peroxide
       TechXtract

Gaseous and vanor systems
•      Chlorine dioxide gas
•      Hydrogen peroxide vapor
•      Paraformaldehyde
•      Methyl bromide

An overview of these technologies was presented in Section 1.

In Chapters 3,4, and 5, the technologies are discussed in detail. For each technology evaluated,
a description of the technology is presented, along with an assessment of its technical maturity
and an evaluation of the existing data. To the extent possible, efficacy data are supplemented by
information and data on material compatibilities, residuals generated, and hardware
performance.  The current uses of the technology outside building remediation are discussed, and
information regarding user concerns, such as health and safety concerns, is addressed. Finally,
the advantages and disadvantages of each technology is  discussed and future research areas are
identified.

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As discussed in Section 2.2, some technologies were not selected for evaluation in this report.
The determination not to evaluate a technology does not imply that the technology is not
effective. In many cases, the outlook for these technologies appears to be quite favorable.
However, at this time, they generally are not close enough to commercialization (nanotech
nanoemulsions, enzymes, photochemical systems), present human health hazards (ethylene
oxide), or are untested in building applications (ozone, plasma, directed energy).  As a result,
they are not covered in this document.

2.4    References for Section 2

Battelle Memorial Institute, 1999. Wide Area Decon: CB Decontamination Technologies,
Equipment and Projects-Literature Search and Market Survey. Report Number AFRL-HE-WP-
TR-2002-0054. U.S. Air Force Research Laboratory, Washington, DC. March 1999 (Available
For Official Use Only)

Mitretek Systems, 2003. Review of Decontamination Technologies for Biological and Chemical
Warfare Agents In Support of the U.S. Environmental Protection Agency's Safe Buildings
Program. U.S. EPA.  Washington, DC. March 2003.  Draft, not released to the public.

NIOSH, 1994.  NIOSH Pocket Guide to Chemical Hazards. U.S. Department of Health and
Human Services. Washington, D.C.  June  1994.

U.S. Department of Health and Human Services, 1993.   Hazardous Substances Data Base.
National Toxicology Program, National Library of Medicine, Bethesda, MD. 1993.

EPA, 2003. Chemical Emergency Preparedness and Prevention. EPA Chemical Profile: Methyl
Bromide. U. S. Environmental Protection Agency.
http://vosemLite.epa.j[oy/oswer/CeppoEHS.n30'Profiles/74-83-9?OpeDDocument. Accessed
October 2004.
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3.     LIQUID-BASED TECHNOLOGIES
                           r-
3.1    Hypochlorite

3.1.1   Technology Description

Historically, chlorine-based decontamination systems have been effectively employed against
chemical agents.  The use of hypochlorite solutions (aqueous and non-aqueous) or solid/slurry
hypochlorites has been widespread for military applications. This general purpose
decontaminant class has been used on personnel, equipment, clothing, building surfaces, and
soil, as shown in Table 3.1-1.  While an effective decontaminant, its corrosive properties,
formation of toxic by-products, and irritant properties are undesirable.  The military typically
uses HTH (high test hypochlorite) and STB (super tropical bleach) along with household bleach
solutions for agent spills and personnel decontamination. The compositions of these materials
include oxides  which assures high pH in aqueous solution and provides a hydrolysis reaction for
additional decontamination.

                       Table 3.1-1. Hypochlorite Decontaminants
Decontaminant
Bleach*
HTH (high test hypochlorite)*
STB (super tropical bleach)*
/
Dutch powder
ASH (activated solution of
hypochlorite)
SLASH (self-limiting activated
solution of hypochlorite)
Composition
2-6% NaOCl in water
Ca(OCl)Cl + Ca(OCl)2 as a solid
powder or a 7% aqueous slurry
Ca(OCl)j + CaO as a solid powder
or as a 7, 1 3, 40, and 70 wt%
aqueous slurries
Ca(OCl)2 + MgO
0.5% Ca(OCl)2+ 0.5% sodium
dihydrogen phosphate buffer +
0.05% detergent in water
0.5% Ca(OCl)2+ 1.0% sodium
citrate + 0.2% citric acid + 0.05%
detergent in water
Application
skin and equipment
equipment and terrain
equipment and terrain
skin and equipment
skin and equipment
skin and equipment
 ' Currently used by DoD
Bleach

Sodium hypochlorite. An aqueous solution of sodium hypochlorite, NaOCl, is often used as a
general purpose decontaminate. Improvements in the effectiveness of the hypochlorite reaction
have been achieved by introducing stronger oxidants to the system. Developed in the 1940's,
calcium hypochlorite (solid) [Ca(OCl)2], STB, and HTH are found to be more effective
decontaminants over a broader range of pH.  More recently, in the early 1990's, the U.S. Army
evaluated the application of hydantoin (specifically dichlorodimethylhydantoin, DCDMH) as an
alternative reactant for chemical destruction of chemical agents. The chlorinating power of
DCDMH is greater than mat of HTH and STB, and has been used successfully to detoxify
mustard,  nitrogen mustard, lewisite,  and phosgene.  However, reaction mechanisms are similar
to hypochlorite, producing the same decomposition products. The exact reaction mechanism of
DCDMH has not been fully developed.
                                          23

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Calcium hypochlorite. Ca(OCl)2 is a powerful oxidizing agent, and is an active component of
both STB and HTH. The hypochlorite ion (OC1~) generated by an aqueous solution of Ca(OCl)2
is effective in the decontamination of G-agents [Sarin (GB), Soman (GD), Tabun (GA)], VX [0-
ethyl-S-(2-diisopropylaminoethyl)methylphosphono-thioate] in acidic solutions, and HD [sulfur
mustard, bis(2-chloroethyl)sulfide].  Hypochlorite ions in high pH (basic) solutions are not very
effective in the decontamination of VX for reasons including:  1) reduced solubility; 2) factor of
10 mole excess; and 3) generation of toxic byproducts. The detoxification of HD by
hypochlorite is a simple process that forms several different products. Both sulfoxide (one S-0
double bond) and sulfone (two S-0 double bonds) species are formed, each of which undergo
elimination reactions to form monovinyl and divinyl sulfoxides and sulfones. It was found that
VX reacts with OC1~ ions at low pH (acidic).  However, at high pH, the solubility of VX is
greatly reduced, and a greater than 10:1 ratio of active chlorine to VX is required to oxidize VX
as compared to a 3:1 ratio under acidic conditions. In the detoxification of VX, the P-S bond is
broken and P-O, S-O, and S=O bonds are formed. When Ca(OCl)2 dissolves, the result is a
solution that also contains hydroxide ions. The hypochlorite behaves as a catalyst in a
detoxification of G agents by the hydroxide ion.

High Test Hypochlorite (HTH18). The first commercial high-assay calcium hypochlorite product
marketed in the U.S., HTH is a solid powder consisting of calcium hypochlorite, and is a
powerful oxidizing agent.  The hypochlorite ion (OC1~) generated by an aqueous solution of
Ca(OCl)2 is effective in the decontamination of G agents, VX in acidic solutions, and HD.
Hypochlorite ions in high pH solutions are not very effective in the decontamination or
detoxification of VX for a variety of reasons.

Super tropical bleach (STB).  STB is a combination of a powerful oxidizers, calcium
hypochlorite, Ca(OCl)2, and a strong base, calcium oxide, CaO. STB is effective in the
decontamination or detoxification of HD, G agents and VX. The hypochlorite ion (OC1~)
generated by an aqueous solution of Ca(OCl)2 and the hydroxide ion formed by the dissolution
of CaO [which produces Ca(OH)J is effective in the decontamination or detoxification of G
agents, VX in acidic solutions, and HD. Hypochlorite ions in high pH solutions are not very
effective in the decontamination of VX for a variety of reasons.

3.1.2  Technical Maturity

Sodium hvpochlorite  (standard bleach) is the most effective disinfectant for industrial
applications, swimming pools, and household cleaning. Its production is based on very pure
chlorine gas and high quality caustic soda (lye). Similar to chlorine, sodium hypochlorite was
initially used as a bleaching agent in the textile industry.

The principal form of hypochlorite produced, sodium hypochlorite (NaOCl), is used as an
aqueous solution (Kirk-Othmer, 1992). Sodium hypochlorite was first registered for use in the
United States as an antimicrobial pesticide in 1957 (EPA, 2004). Sodium hypochlorite has
proven to be effective against a wide range of bacteria, fungi, and viruses. It is registered by the
EPA for use in the sanitization and disinfection of household premises, food processing plants,
and agricultural settings. It is also used in animal facilities, hospitals, human drinking water
supplies, chemical pulp and textile bleaching, as a commercial laundry and household bleach, as
a sanitizer for swimming pools, and as a disinfectant for municipal water and sewage (Kirk-


                                          24

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Othmer, 1993; EPA, 2004).  Sodium hypochlorite solutions are sold for household purposes at 5-
6 percent concentrations, while 10-15 percent concentration solutions are sold for swimming
pool disinfection, institutional laundries, and industrial purposes (Kirk-Othmer, 1992).

In food processing, sodium hypochlorite is used as a disinfectant and sanitizer (Kirk-Othmer,
1993). NaOCl may be used in washing and lye peeling of fruits and vegetables, and both sodium
and calcium hypochlorite may be used as a final sanitizing rinse on food processing equipment
(EPA, 1991).  Hypochlorite is still used in pulp bleaching, but its use is decreasing because the
bleaching reaction generates chloroform (Kirk-Othmer, 1992).

Synonyms and trade names for sodium hypochlorite include Clorox®, bleach, liquid bleach,
sodium oxychloride, Javex®, antiformin, showchlon, Chlorox, B-K, Carrel-Dakin solution,
Chloros, Dakin's solution, hychlorite, Javelle water, Mera Industries 2MOm3B®, Milton,
modified Dakin's solution, Piochlor®, and 13 percent active chlorine.

Sodium hypochlorite is generally sold in aqueous solutions containing 5 to 15 percent sodium
hypochlorite,  with 0.25 to 0.35 percent free alkali (usually NaOH) and 0.5 to 1.5 percent NaCl.
Solutions of up to 40 percent sodium hypochlorite are available, but solid sodium hypochlorite is
not commercially used. Sodium hypochlorite solutions are a clear, greenish yellow liquid with
an odor of chlorine. Odor may not provide an adequate warning of hazardous concentrations.
Sodium hypochlorite solutions can liberate dangerous amounts of chlorine or chloramine if
mixed with acids or ammonia. Anhydrous sodium hypochlorite is very explosive. Hypochlorite
solutions should be stored at a temperature not exceeding 20 °C away from acids in well-fitted
air-tight bottles away from sunlight.

Calcium hvpochlorite. Ca(OCl)2, is the principal form of solid hypochlorite produced
commercially. Water treatment is the largest use of calcium hypochlorite. Calcium hypochlorite
was first registered for use as a pesticide in 1957. Calcium hypochlorite (65-70 percent available
Cy is used for disinfection in swimming pools, drinking water supplies, and for treatment of
industrial cooling water.  Its cooling water applications include slime control of bacterial, algal,
and fungal origin. Calcium hypochlorite is also used for disinfection, odor control, and
biological oxygen demand (BOD) reduction in sewage and wastewater effluents.  It is used as a
sanitizer in households, schools, hospitals, and public buildings, and is used for microbial control
in public eating places. Calcium hypochlorite is used for bacterial and odor control, and general
sanitation in many food-related industries including dairies, wineries, breweries, canneries, food
processing plants, and beverage bottling plants (Kirk-Othmer, 1993). High assay calcium
hypochlorite (70-74 percent available C12) was first commercialized in the United States in 1928
under the trade name HTH. It is now produced by two additional manufacturers in North
America (Kirk-Othmer, 1993).

Calcium hypochlorite is a white crystalline solid, decomposes at 100°C, decomposes in water
and alcohol, is not hygroscopic, and is practically clear in water solution. It is toxic by ingestion,
skin contact, and inhalation. Calcium hypochlorite is generally available as a white powder,
pellets, or flat plates. It decomposes readily in water or when heated, releasing oxygen and
chlorine.  It has a strong chlorine odor, but odor may not provide an adequate warning of
hazardous concentrations. Calcium hypochlorite is not flammable, but it acts as an oxidizer with
combustible material and may react explosively with ammonia, amines, or organic sulfides. It
becomes a dangerous fire risk in contact with organic material. Calcium hypochlorite should be
                                          25

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stored in a dry, well-ventilated area at a temperature below 120 *F (50 °C), separated from acids,
ammonia, amines, and other chlorinating or oxidizing agents.

Synonyms and trade names for calcium hypochlorite include losantin, hypochlorous acid,
calcium salt, B-K Powder, Hy-Chlor®, chlorinated lime, lime chloride, chloride of lime, calcium
oxychloride, HTH, mildew remover X-14®, Perchloron®, and Pittchlor®.

Super tropical bleach was standardized in the 1950s. It is a mixture of 93 percent calcium
hypochlorite and 7 percent sodium hydroxide and is more stable than bleach in long-term storage
and easier to spread (Modec, 2003).  This stability makes super tropical bleach useful for
application in hot, humid climates (Kirk-Othmer, 1992).

Sodium and calcium hypochlorite are extremely corrosive, causing severe damage to the eyes
and skin upon contact.  Because of these acute effects, they have been assigned to Toxicity
•Category I, the highest degree of toxicity, by EPA. Residues of sodium and calcium
hypochlorite that may remain on certain food crops disinfected with the chemicals pose no
known human health hazard (EPA,  1991).

Due to the acute toxicity of these products, protective clothing, safety glasses or goggles, and
chemical-resistant gloves are required while handling and applying products that contain sodium
or calcium hypochlorite as the active ingredient.  Re-entry levels must be met before entering
swimming pools,  hot tubs, or spas treated with sodium or calcium hypochlorite, and reentry
intervals must be observed before using food and non-food contact surfaces that have been
sprayed or fogged with either chemical (EPA, 1991).

3.1.3  Applications of the Technology

Chlorine-based aqueous solutions have been considered as general purpose decontaminants since
World War I.  Many studies have been performed to evaluate their effectiveness on chemical
agents.  Chemical oxidation is applicable to the decontamination process. The reaction
chemistry is very complex and varies between the different chemical agents. The reactions
process is highly dependent on the pH of the solution, solubility of the agent, and competing
hydrolysis reactions producing undesired reaction products in some cases.

The requirement for chemical agent decontamination dates back to World War I when Germany
unleashed HD on Allied troops at Ypres, France in 1915. Prior to that time, the poisonous
chemicals used on the battlefield, such as chlorine, were non-persistent gases and required no
decontamination.  The first decontaminants used were bleaching powders and, to a lesser extent,
potassium permanganate.  The reactions of chemical agents with excess bleach are so vigorous
that both neat and thickened agents can be converted to less or nontoxic products  at the
liquid-liquid  (bleach solution) or liquid-solid (bleach powder)  interface in a few minutes.
Solubilization of the agents in the same medium as the bleach is not required.  HD is converted
into a series of oxidation and elimination products. It is believed that the sulfoxide is formed
first, followed by sulfone formation.  Subsequently, both oxidation products undergo elimination
reactions in the strongly basic solution to produce the corresponding monovinyl and divinyl
sulfoxides and sulfones, although small amounts of additional  unidentified products are also
present in the final solution (Yang, 1992).
                                           26

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By World War II, superchlorinated bleaches, shown in Table 3.1-1, were used as the most
common general purpose decontaminants. However, there are some disadvantages to using
bleach as a decontaminant: 1) the active chlorine content of the bleach gradually decreases with
time so that a fresh solution must be prepared prior to each use; 2) a large amount of bleach is
required for the oxidation of the agents; and 3) bleach is corrosive to many surfaces.

Common oxidants used for decontamination are bleaches that produce active chlorine. Active
chlorine exists in water in equilibrium with the hypochlorite ion, 3C1O~ = 2C1" + C103~.  STB
[Ca(OCl)2 + CaO] and HTH [Ca(OCl)Cl + Ca(OCl)2], are prepared as slurries that are a mixture
of water and solid bleach powders.

During the remediations of several of the buildings that were impacted by the 2001 anthrax mail
attack, household bleach - diluted 10:1 (to 0.525% to 0.6% NaOCl), and adjusted to  a pH near
neutral - was used with apparent success in wiping down surfaces contaminated with B.
anthracis. This application for B.  anthracis was authorized by a crisis exemption issued by EPA
under Section 18 of FIFRA, following EPA testing of the pH-modified bleach using the AOAC
Sporicidal Activity Test (AOAC, 2000).  Based upon this testing, the crisis exemption specified
that the bleach solution had to be adjusted to a pH near 7, that it be utilized only on hard (non-
porous) surfaces, and that the surfaces remain wetted with the bleach solution for no  less than 60
minutes.  The crisis exemption also required that - following the total remediation process for
these buildings, including the bleach wipe-down step - environmental sampling be conducted
within the treated areas of the buildings to confirm the efficacy of the total procedure. The
results of the sporicidal activity testing are discussed in the following section.

       Further discussion of the crisis exemption for the use of bleach against B. anthracis can
be found on EPA's web site at:
wvv'w.epagov/pesticides/factsheets/chemicals/b)eachfactsheet.htm.

3.1.4  Compilation of Available Data

Chemical agents. The U.S. Army's Field Manual 3-9 recommends the use of hypochlorite for
decontamination of chemical agent spills and equipment clean up (U.S. Army, 1990). Field
Manual 3-5, NBC Decontamination (U.S. Army, 2002),  lists STB and HTH as standard
decontaminants, and bleach as a non-standard decontaminant. STB and HTH are not
recommended for ship use, whereas bleach is.

Laboratory studies have documented that aqueous solutions of hypochlorite can successfully
eliminate chemical agents (HD, GB, GD, GA, and VX) below 1 part per million with reaction
half lives of 1.5 minutes or less (Yurow, 1991).

G agents can be rapidly detoxified in bleach solutions. The hypochlorite anion behaves as a
catalyst breaking the P-F bond in GB  and GD (and P-CN bond in GA), substituting a hydroxyl
group to the P atom and releasing the fluoride (or cyanide) ion (Epstein, 1956).  The  elimination
of the fluoride (or cyanide) creates a less toxic phosphono  compound.
                                                                    4
Bleach can also be used for the decontamination of VX, particularly under low pH conditions.
VX readily dissolves in acidic solutions via protonation  of the nitrogen while the sulfur is
oxidized by HC1O. Under such acidic conditions, only three moles of active chlorine are
                                          27

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consumed for each mole of VX.  At high pH, the solubility of VX is significantly reduced. The
non-protonated nitrogen is oxidized, accompanied by the evolution of chlorine or oxygen gas
and the formation of sulfate and carbonate salts.  Under basic conditions, more than 10 moles of
active chlorine are required to oxidize 1 mole of VX. Despite the long history of alkaline bleach
solutions as general purpose decontaminants for the chemical agents, the precise stoichiometry at
high pH has not been determined for VX (Yang, 1992).
                                                                              i
Biological agents. Decontamination of biological simulant (bacillus subtilis var. niger, known
as Bg) with sodium hypochlorite was reported in a Battelle report (Battelle, 1999). The
effectiveness of three decontaminants was compared. The decontaminants were: 1) pH-adjusted
sodium hypochlorite (ASH) composed of household bleach (5.25 percent by weight), white
vinegar for pH adjustment (5 percent acid strength), and dilution water; 2) diluted bleach (5.25
percent by weight sodium hypochlorite), diluted with water; and 3) plain water.  The results
(Table 3.1-2) indicate that ASH was the most effective decontaminant against the Bg, effectively
reducing the spore count by 99.6 percent.

The conclusions reached from this study were:  1) ASH performed better than either diluted
bleach or plain water; 2) the presence of dirt, mud, and foreign material will greatly reduce the
germicidal power of ASH; and 3) the decontamination process is limited to small areas and
easily reachable locations. Subsequent studies report that hypochlorous acid (2.5 percent
aqueous solution) had a 100 percent Bg spore kill rate at relative humidity (RH) of 100 (CBIAC
and AD - A084392, as referenced in Battelle, 1999).

                   Table 3.1-2. Residual Agent after Decontamination
Decontamination
Solution
Water


Bleach


ASH


Sample #
1
2
3
1
2
3
1
2
3
Total Spores on Strip After
Spray
8.9x10"
6.2 xlO4
3.6 xlO4
4.5 xlO4
4.0 xlO4
4.0 xlO4
1.1x10"
5.3 xlO3
5.6 xlO3
Average Percent
Reduction
96.8


98.0


99.6


Diluted sodium hypochlorite was tested by EPA for its sporicidal activity following the 2001
anthrax mail attacks, to support a crisis exemption under FIFRA that would allow the use of this
product against B, anthracis spores in some of the affected buildings. Tests were conducted
using the AOAC Sporicidal Activity Test (AOAC, 2000). The product tested was household
bleach (6% NaOCl) that had been diluted with water by a 10:1 ratio, resulting in a 0.525%
solution.  Two such dilute solutions were tested: bleach that had been diluted with pure water
(resulting in a pH of 10.2); and bleach that had been diluted with water and with white vinegar,
in order to achieve a final solution pH of 6.5, near neutral. Consistent with the AOAC protocol,
the sporicidal efficacy of these two solutions was tested using two surfaces inoculated with 106
to 107  B. subtilis spores: porcelain penicylinders (representing hard, non-porous surfaces) and
silk suture loops (representing porous surfaces).  The AOAC test does not determine the
                                          28

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quantitative log kill of the spores; it measures qualitatively whether or not all the spores on the
surface were killed.

      The results of the testing on the porcelain penicylinders showed that - with the pH-
adjusted 0.525% NaOCl - more than 90% of the penicylinders had complete kill after 30
minutes of exposure time, and every cylinder showed complete kill after 60 minutes. By
comparison, the non-adjusted (high-pH) bleach still showed live spores on 40% of the
penicylinders after 30 minutes.

      The results of the testing with the silk suture loops showed live spores on essentially all
of the loops, even after 90 minutes of exposure time.

      On the basis of these efficacy results, EPA issued a crisis exemption for the use of
sodium hypochlorite solutions in the B. anthracis remediation activities, with the following
provisions: it is for use only on hard surfaces; the solution must be pH-neutral, with a NaOCl
concentration between 0.5% and 0.6%; and the contact time of liquid solution on the surface
must be no less than 60 minutes (with the solution having to be re-applied if the surface dries
prior to (hat time). Additionally, post-remediation sampling must be performed to confirm that
the remediation process - including the bleach application step, and any other steps that are
performed (e.g., including fumigation) - has in fact been efficacious.

      Issuance of a crisis exemption requires that EPA consider the safety of a product, as well
as the product's efficacy. The Agency's review deemed this product to be safe for use with
proper protective measures, since it is already registered under FIFRA for other (disinfection)
applications.

3.1.5  Concerns for the User (Applicability)

Calcium hypochlorite is a white, crystalline, and oxidizing solid material which looks much like
table salt.  The solid material has a faint odor of chlorine, and can be toxic by ingestion, skin
contact, and inhalation.  Calcium hypochlorite is used as  a disinfectant in swimming pools,
sewage treatment operations, and in water treatment operations.

Solid calcium hypochlorite should not be stored near reactive or combustible materials. Fires
involving  calcium hypochlorite may be difficult to put out because if calcium hypochlorite is not
kept completely dry, it will decompose liberating oxygen and chlorine. A spontaneous fire or
explosion  could result if solid Ca(OCl)2 is not kept dry and is stored with organic or other
flammable material(s).  Therefore, calcium hypochlorite must be stored in a completely dry
location, isolated from combustible materials, or fully dissolved to prevent creating a hazardous
condition.

Hypochlorites should be used as aqueous solutions. Contact with organic materials  in the dry
form may  cause fires or generation of toxic gases. The MSDSs for different forms of bleach and
calcium hypochlorite are available on the web.

3.1.6  Availability of the Technology for Commercial Applications
                                           29

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Sodium- and calcium-based hypochlorites are commercially available under a range of brand
names, as discussed in the preceding sections.

Historically, hypochlorite decontamination solutions have been used to decontaminate biological
organisms in small areas, personal protective equipment, and contaminated floor/ground/wall
surfaces. The systems are "low tech", that is, hand sprayers, buckets, mops, rags, brushes, etc.
are used to apply the solution to the contaminated surfaces with vigorous scrubbing followed by
a water rinse.  EPA's testing using the AOAC Sporicidal Activity Test has shown that diluted
household bleach (NaOCl) is effective in achieving a six- to seven-log reduction in Bacillus
subtilis spores when applied to hard, non-porous surfaces, if the sodium hypochlorite is adjusted
to a pH of 7, and is allowed to contact the surface for 60 minutes. Diluted bleach was not found
to be effective on porous surfaces (silk suture loops) in the AOAC test.

Hypochlorites are also used by the military to decontaminate spills of G and VX chemical
agents.  For VX decontamination to be effective, the pH of the bleach must be low.

3.1.7   Advantages and Disadvantages

Hypochlorite solutions are relatively available (household bleach is available in any grocery
store, HTH is available from swimming pool supply and chemical companies), low-cost, and
easy to obtain.  The application is low tech and requires  little knowledge  of equipment operation.
However, the user must be aware of the dilution, pH adjustment, and contact time requirements
for treatment to be effective, as defined by EPA's AOAC testing.

The corrosive nature of hypochlorite solutions requires care to be taken to ensure materials
treated are resistant to the oxidative process. Attention to waste containment and recovery is
required. The waste generated from the use of high-concentration, non-pH-adjusted
hypochlorites should be considered to be hazardous and handled accordingly. However, the
wastewater may be declared non-hazardous if when bleach is used in accordance with the EPA
crisis exemption (i.e., it is diluted to 0.5 to 0.6% NaOCl concentration, and the pH is  adjusted
with vinegar to be near neutral).
                                           30

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3.1.8  Potential Areas for Future Research (Uncertainties)

Further research is needed to systematically quantify the concentration, solution pH, and length
of contact time required for hypochlorites (in particular, NaOCl) to be effective on a variety of
biological agents (in addition to B. subtilis spores) on both non-porous and porous surfaces.
Similar testing is needed for the range of hypochlorites, quantifying concentration, pH, and
contact time required for efficacy against chemical agents.

3.1.9  References for Section 3.1

AOAC, 2000. Official Methods of Analysis, 17th ed.: Method 966.04. AOAC International,
Gaithersburg, MD.

Battelle, 1999. Wide Area Decontamination: CB Decontamination Technologies, Equipment,
and Projects—Literature Search and Market Survey. Report to the U.S. Joint Service Materiel
Group by Battelle Memorial Institute and Charles W. Williams, Inc.  March 1999.

EPA, 1991. Reregistration Eligibility Document - Sodium and Calcium Hypochlorite Salts,
738-F-91-108.

EPA, 2004. Pesticides: Topical & Chemical Factsheet - Bleach. U. S. Environmental
Protection Agency, www.epa.gov/pesticides/factsheets/chemicals/bleachfactsheet.htm.
Accessed November 2004.

Epstein, 1956. Epstein J; Bauer, V.E.; Saxe, M.; and Demek, M.M.  Journal of the American
Chemical Society, 78: 4068-4071.

Modec, 2003. Formulations for the Decontamination and Mitigation ofCB Warfare Agents,
Toxic Hazardous Materials, Viruses,  Bacteria and Bacterial Spores. Modec, Inc.  Technical
Report MOD2003-1012-G. Issued February 2003.

Kirk-Othmer, 1992. Encyclopedia of Chemical Technology, Fourth Edition, Volume 4,
"Bleaching Agents," pp. 271-310.

Kirk-Othmer, 1993. Encyclopedia of Chemical Technology, Fourth Edition, Volume 5,
"Chlorine Oxygen Acids  and Salts (C1O2, HOC1)," pp. 951-957.

U.S. Army, 1990.  Army  Field Manual No. 3-9, Potential Military Chemical/Biological Agents
and Compounds.

U.S. Army., 2002.  Army  Field Manual 3-5, NBC Decontamination.

Yang, Y.-C.; Baker, J. A.; and Ward,  J.R.  "Decontamination of Chemical Warfare Agents,"
Chem. Review 1992,92: 1729-1743.

Yurow, H.W., 1981. "Decontamination Methods for HD, GB, and VX, A Literature Survey".
ARCSL-SP-80032.
                                         31

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3.2 Aqueous Chlorine Dioxide

3.2.1  Technology Description

Chlorine dioxide possesses disinfection properties in both its aqueous and gaseous states. The
focus of this section is an evaluation of aqueous chlorine dioxide.

Chlorine dioxide (C1O2) is unstable and therefore must be generated at the use site, typically
using sodium chlorite as a reactant. Aqueous chlorine dioxide is generated for use as a hard
surface cleaner by adding gaseous chlorine dioxide to water. Gaseous chlorine dioxide is
generated via the mechanisms and equipment described in Section 5.1 of this document. Gas
generated in this manner can be subsequently dissolved in water.  For example, gas generators
discussed in Section 5.1 can generate both gaseous and aqueous chlorine dioxide.

Aqueous chlorine dioxide can also be generated by acidifying an aqueous sodium chlorite
(NaClO2) solution. So-called "stabilized chlorine dioxide" is a commercially available solution
of sodium chlorite, pH-adjusted to be slightly basic.  This basic sodium chlorite forms a chlorine
dioxide solution with the addition of acid,  and is thus sold as a 'two-part' formulation (Purogene,
2003). However, the apparent instructions for at least one product is to dilute the concentrated
product in water and apply to surfaces (Neways, 2001). In this case, the precise mechanism by
which the sodium chlorite forms chlorine dioxide is unclear.

Regardless of whether aqueous chlorine dioxide solutions are generated onsite from gaseous
chlorine dioxide, or from sodium chlorite or stabilized chlorine dioxide solutions, they are
applied manually to hard surfaces for disinfection with a sponge or mop, or as a spray.

3.2.2 Technical Maturity

Aqueous chlorine dioxide has been recognized for its disinfectant properties since the early
1900's, and was first registered by EPA as a disinfectant and sanitizer in 1967. Sodium chlorite-
based cleaners are used in the food processing industry for cleaning of surfaces and of food
itself.  Chlorine dioxide has extensive use  in drinking water treatment, generated from sodium
chlorite and fed into the water. These applications, and the biological organisms commonly
present in these industries, are reflected in the available data regarding chlorine dioxide's
effectiveness.
                                                                                       i
3.2.3 Applications of Aqueous Chlorine Dioxide

Wood pulp bleaching is the largest use of aqueous chlorine dioxide.  Other aqueous chlorine
dioxide applications include, but are not limited to, textile bleaching, treatment of municipal
water supplies, and disinfection of food and food processing equipment. Specific examples of
such applications are discussed in Section 5.1.3 of this document.

3.2.4 Evaluation of Available Data

Various research has been conducted to test the disinfection capabilities of aqueous chlorine
dioxide. Much research has been conducted on the use of aqueous C1O2 in water distribution

                                           32

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systems.  There has also been a significant amount of data generated on the effectiveness of
aqueous C102 as a food disinfectant  Aside from these uses, there is little experimental data
regarding aqueous chlorine dioxide surface disinfection applications.  The majority of the
research conducted has been laboratory scale, aimed at determining the efficacy of C102 in the
destruction of pathogens and viruses deemed likely to be contaminants in those applications.

This section discusses available data concerning the effectiveness of chlorine dioxide in
destroying bacteria, fungi, and viruses.  Based on the data presented, the following general
conclusions can be drawn regarding chlorine dioxide performance:

*      All data pertain to biological organisms. No data are available regarding chemical
       agents.
•      Aqueous solutions of stabilized chlorine dioxide (slightly basic NaClO2) must be
       properly activated with acid prior to use. Sodium chlorite has very few biocidal
       properties by itself.
•      Chlorine dioxide reacts very fast with the target organism; after 5 minutes no significant
       additional reaction is typically expected.
•      Chlorine dioxide is effective against certain types of bacteria, fungi, and viruses.
       However, the chemical performs better against some organisms than others. As a result,
       there is uncertain predictive capability in applying results to untested organisms.

In November 2001, EPA's Office of Solid Waste and Emergency Response issued a crisis
exemption under Section 18 of FIFRA allowing the limited sale, distribution, and use of
products containing aqueous chlorine dioxide for surface cleaning of buildings contaminated
with spores of Bacillus anthracis.  On March 28,2002, this crisis exemption was amended to
specify the conditions for use of aqueous chlorine dioxide for decontamination. This
amendment allowed for the disinfection of hard surfaces only. Furthermore, the amendment
specified the concentration of aqueous chlorine dioxide to be 500 mg/L, to be applied at room
temperature (68 °F), with a minimum contact time of 30 minutes (EPA 2001, EPA 2002).

       Further discussion of the crisis exemption for the use of aqueous C1O2 against B.
anthracis can be found on EPA's  web site at:
          www.epa.gov/pesticides/faetaheets/cheroicals/chtoririedioxidefactsheet.htm

Disinfection/Sterilization for Bacteria and Spores
»
Several tests have been conducted to determine the effectiveness of commercially available
cleaners to destroy bacteria or other organisms. One test assessed the ability of various
commercially available cleaners and  sanitizers to remove bacteria from various surfaces
including stainless steel and plastic (Krysinski, 1992). Material contaminated with Lwfer/a
monocytogenes organisms were submerged in solutions for 10 minutes and then evaluated for
efficacy. Results are presented in Table 3.2-1. Stainless steel was the 'easiest' material to
disinfect, while a polyester/polyurethane conveyer belt was the 'hardest.'  The log kill is modest
at these concentrations and exposure times.
I
                                                                                                  <
                                           33

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   Table 3.2-1. Deactivation ofListeria monocytogenes Using Chlorine Dioxide Solutions
Sanitizer or Cleaner
Chlorine dioxide (5 ppm)
sanitizer
Chlorine dioxide (5 ppm) +
acidic quaternary ammonium
compound (QAC) sanitizer
Detergent/chlorine dioxide
blend of cleaner
Log Kill and Final Organism Count
Etched Stainless
Steel
Log kill >3. 3 (Final
<20CFU/cm2)
Log kill >3.3 (Final
<20CFU/cm2
Log kill >3.2 (Final
< 20 CFU/cm2)
Polyester
Log kill >3.2 (Final
< 20 CFU/cm2)
Log kill >3. 2 (Final
< 20 CFU/cm2)
No data
Polyester/
Polyurethane
Log kill 0,7 (Final
9,000 CFU/cm2)
Log kill 2.0 (Final
500 CFU/cm2)
Log kill 1.4 (Final
2,000 CFU/cm2)
Source: Krysinskietal., 1992.
Log kill calculated as the ratio of the final counts following treatment with solution versus the final counts
of the control (no cleanser). Ten minute contact time.
Harakeh (1988) evaluated a solution of a commercially available stabilized chlorine dioxide
solution (Purogene) for the destruction of various bacteria as a function of time and pH. Bacteria
were mixed with the chlorine dioxide solution. The concentration of chlorine dioxide evaluated
was very low (0.75 mg/L) in comparison to the use levels of 500 mg/L cited in the EPA
memoranda Nevertheless, the following conclusions and observations were identified:

•      Based on tests with E. coli, pH had a significant effect on destruction.  The product was
       acidified to varying degrees; the greatest inactivation occurred at the lowest pH tested
       (3.5),  Essentially, ho inactivation occurred in the pH range of 5 to 8.7. Results are
       illustrated in Table 3.2-2.
*      The degree of inactivation is dependent on the specific organism, as shown in Table 3.2-
       3.
•      The highest degree of inactivation occurred within 60 seconds. Inactivation 'flattened
       out' between 1 and 15 minutes.  For example, Table 3.2-3 illustrates that the inactivation
       measured after 5 minutes is not significantly more than the inactivation measured after 15
       minutes.  A similar observation has been noted in other tests using sodium chlorite-
       containing disinfectants (Mullerat et al., 1995).

        Table 3.2-2. Effect of Adding Acid to Stabilized Chlorine Dioxide Solution
pH
8.7 (initial product pH)
7
6
5
3.5
Log Inactivation of E.
coli After 5 Minutes
0.0
0.0
0.0
0.4
3.8
Source: Harakeh (1988). Tests conducted on stabilized chlorine dioxide product at 23 °C. Chlorine
dioxide concentration of 0.75 mg/L.
                                            34

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      Table 3.2-3.  Effectiveness of Acidified Stabilized Chlorine Dioxide on Bacteria
Bacteria
Escherichia Coli
Pseudomonas aeruginosa
Yersinia enterocolitica
Klebsiella pneumoniae
Streptococcus pyogenes
Salmonella typhimuritm
Bacillus subtilis
Log Kill After 5 Minutes
5.6
5.2
5.2
5.0
1.9
9.0
4.5
Log Kill After IS Minutes
5.6
5.4
5.2
5.0
1.9
9.9
4.5
Source: Harakeh et al, 1988. Tests conducted on stabilized chlorine dioxide product adjusted to pH 3.5
at 23 C.  Chlorine dioxide concentration of 0.75 mg/L.
With the rising use of chlorine dioxide in water distribution systems, much research has been
conducted to verify the disinfectant abilities of chlorine dioxide as used in water treatment
facilities. For example, Tarquin and Rittmann (1993) have reported a chlorine dioxide
disinfection study conducted in El Paso, Texas, in which chlorine dioxide was tested for its
ability to reduce coliforms and total plate counts at El Paso's 20 million gallon per day surface
water treatment plant Chlorine dioxide was generated onsite and injected into the treatment
plant's second set of settling tanks at a concentration of 1 mg/L, Samples were collected before
and after treatment to measure coliform bacteria and total plate counts. Table 3.2-4 presents the
results of the coliform analyses. The average coliform reduction was 83 percent.

Table 3.2-4. Coliform Reduction in Drinking Water Treated with Chlorine Dioxide
Date
7/31
8/07
8/14
8/21
8/28
Average .
Coliform Count/100 ml
(before CIO,)
860
360
620
230
385
491
Coliform Count/100 ml
(after CIO*)
43
12
360
0
0
83
Percent
Reduction
95
97
42
100
100
83
Source: Tarquin and Rittmann, 1993.
Chlorine dioxide administered continuously at 1 mg/L.

Similar reductions were reported for total plate counts.  Plates for samples that had been
subjected to chlorine dioxide disinfection had approximately 85 percent less growth than those
samples that were not subjected to C1O2 treatment.

Tanner (1989) tested the biocidal activity of commercial disinfectants containing chlorine
dioxide. Three organisms were tested using a modified version of the Association of Official
Analytical Chemists (AOAC) use-dilution method in which a disinfecting material is combined
with a test organism in a solution. Pseudomonas aeruginosa, Staphylococcus aureus, and
                                           35
                                                                                                   i

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Saccharomyces cerevisiae samples were added into the chemical solutions. Samples were drawn
after 30 seconds and 60 seconds of contact time.  Chlorine dioxide was used at a concentration of
500 mg/1 and diluted to lower levels. Table 3.2-5 presents the concentration required to achieve
a 5 log reduction (99.999 percent) in viable cell counts after one minute of contact time.

Table 3.2-5. Chlorine Dioxide Concentration for 5-log Reduction in Cell Count at 60
       Seconds
Species
Pseudomonas aentginosa
Staphylococcus aureus
Saccharomyces cerevisiae
Concentration (mg/L)
CIO,
48
93
95
Acidified Sodium Chlorite
310
1300
640
Tanner, 1989.
Tests conducted at 22°C.

Ten other chemicals (including sodium hypochlorite and hydrogen peroxide) were also subjected
to the same biocidal activity tests.  According to Tanner's results, while other chemicals such as
these similarly achieved 5-log reduction against the three organisms, lower levels of chlorine
dioxide were required than for other products.

The effectiveness of chlorine dioxide for inactivating other bacteria was determined by Chauret
et al. (2001). B. subtilis spores, Clostridium sporogenes spores, and C. parvum oocysts were
evaluated. A 99 percent pure chlorine dioxide solution (generated onsite) was introduced into an
aqueous suspension of the organisms. Samples were extracted at various time intervals to
determine the remaining organism counts. Results were presented for various concentrations
and time intervals and are summarized in Table 3.2-6. A lower concentration-time value
corresponds to quicker reaction time or lower required solution concentration.

               Table 3.2-6.  Inactivation of Bacteria with Chlorine Dioxide
Organism
C, parvum
B. subtiiis
C. sporogenes
Concentration-time (mg-min/L)
75 - 1,000
-75
-75
Log inactivation
2.0
2.0
2.0
Source: Chauret et al, 2001.
Results are given using the most probable number (MPN)-cell infectivity method.
Deactivation of C parvum was determined for oocysts purchased from several different suppliers; a range
is presented here.
Aqueous chlorine dioxide was tested by EPA for its sporicidal activity following the 2001
anthrax mail attacks, to support a crisis exemption under FIFRA that would allow the use of this
product against B. anthracis spores in some of the affected buildings. Tests were conducted
using the AOAC Sporicidal Activity Test (AOAC, 2000). The product tested contained either
                                           36

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500 or 1,000 mg/L C102, with 0.1% v/v surfactant.  The sporicidal efficacy was tested using two
surfaces inoculated with 106 B. subtilis spores: porcelain penicylinders (representing hard, non-
porous surfaces) and silk suture loops (representing porous surfaces). The AOAC test does not
determine the quantitative log kill of the spores; it measures qualitatively whether or not all the
spores on the surface were killed.

       The results of the testing on the porcelain penicylinders showed that, with the 500 mg/L
solution, only one of the 60 penicylinders failed to have complete kill after 10 minutes of
exposure time, and every cylinder showed complete kill after 30 minutes.  By comparison, with
the silk suture loops, every one of the loops contained live spores even after 90 minutes of
exposure time to a solution containing 1,000 mg/L.

       On the basis of these efficacy results, EPA issued a crisis exemption for the use of
aqueous C1O2 solutions in the B, anthracis remediation activities, with the following provisions:
it is for use only on hard surfaces; the solution must have a C1O2 concentration of 500 mg/L; the
contact time of liquid solution on the surface must be no less than 30 minutes; and applications
should be made at room temperature (about 68 °F, or 20 °C). Additionally, post-remediation
sampling must be performed to confirm that the remediation process - including the aqueous
C1O2 application step,  and any other steps that are performed (e.g., including fumigation) - has
in fact been efficacious. Any remaining aqueous C1O2 must be removed from the treated areas
before persons without protective equipment are allowed to re-enter.

Fungicidal Activity

The effectiveness of chlorine dioxide as a fungicide was tested on post-harvest decay fungi and
filamentous fungi.  Griffith et al. (1999) reported a 1994 study by Roberts and Reymond where
in vitro tests onMucor piriformis, Botrytis cinerea, Penicillium  expansion, and Cryptosporiopsis
perennans were conducted. Conidial suspensions of each pathogen were pipetted into test tubes
containing C1O2 at concentrations of 1,3, and 5 mg/1. Samples were drawn at 30 second
intervals and the number of viable colony forming units/ml (CPU) was determined.  The results
of the tests are presented in Table 3.2-7.

These experimental results indicate that deactivation is influenced by time, concentration, and
organism type. Complete deactivation (to the limits of the test)  was recorded for each organism
at the highest concentrations and time identified (5 mg/L and 4 minutes); lower concentrations or
lower contact times resulted in poor results for some organisms.
                                           37

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Table 3.2-7. Mortality of Fungi After in vitro Contact with OO2 at Various Concentrations
and Contact Times
Fungus
Cryptosporiopsis
peremans
Mucor piriformis
Penicillium
expansion
Botrytis cinerea
ppm
CIO,
1
3
5
1
3
5
1
3
5
1
3
5
Percent spore mortality
30 sec.
100
100
100
85
100
100
42
99
100
35
94
99
60 sec.
100
100
100
93
100
100
77
99.9
100
49
99
99.5
120 sec.
100
100
100
99.9
100
100
99
100
100
94
99.7
100
180 sec.
100
100
100
99.9
100
100
99.6
100
100
98
99.9
100
240 sec.
100
100
100
100
100
100
99.8
100
100
99
99.9
100
Griffith et al., 1999.
Samples were diluted and placed onto malt extract agar. CPU determined after a 2-3 day incubation
period.
Virucidal Activity

In a 1981 publication by Roberts as reported by Griffith et al. (1999), the virucidal activity of
chlorine dioxide was tested for the inactivation of human infectious viruses in the effluent of
three municipal waste treatment, sewage sludge facilities in the San Francisco Bay area.
Poliovirus ILSC was used in these experiments due to its potential as an indicator for the
Hepatitis viruses.- These experiments were conducted using coliphage of Escherichia coli and
inoculum of the Poliovirus I in secondary effluents. Samples were taken at various time
intervals following 2 ppm and 5 ppm dosing of C102.  Based on the authors' determination that
phage survival would be indicative of the inoculum survival, coliphage survival was determined
using the Kott Method and Reverse Phage Titer Rise Reaction (RPTRR) Method. Table 3.2-8
represents the results of the experiments, as extrapolated from a graph presented in the 1981
Roberts publication. The values are indicative of the reduction in viable organism count.
                                           38

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              Table 3.2-8. CIO, Control of PoliavimsL in Treated Sewage
C1O2 Dosage
2ppm
5 ppm
Log Reduction of Viruses
2 minutes
1.2
3.2
5 minutes
2.0
3.7
10 minutes
2.4
4.0
30 minutes
2.5
4.7
Griffith etal., 1999

Table 3.2-8 shows that virus reduction is significantly increased with only slightly higher
chlorine dioxide levels. Griffith et al. (1999) identified that the mortality of coliform bacteria
was similar to the results in Table 3.2-8.

Biofilm Control

Mayack et al. (1984) tested the effectiveness of using chlorine dioxide for the control of biofilm.
Table 3.2-9 presents data extrapolated from a graph in the Mayack document, showing the dry
weight and total organic carbon (TOC) reductions after chlorine dioxide use.  Table 3.2-9 shows
an 82-91 percent reduction of dry weight biofilm and a 92-96 percent reduction of TOC in
biofilm at these conditions.

                         Table 3.2-9. CIO, Bio-Fouling Control
Chemical
Control
C1O2
1 ppm 1 hr/day
Dry wt. mg/cm2
2.10
0.38
TOC mg/cm2
0.75
0.06
1 ppm 15 minutes/4 times daily
Dry wt. mg/cm2
2.10
0.18
TOC mg/cm2
0.75
0.03
Source: Mayack et al., 1984.

An example of the importance of biofilm control is in the control ofLegionella pneumophila, the
bacteria identified in 1976 as responsible for Legionnaires' Disease. This disease is thought to
be caused by the inhalation of bacteria contained in water mists from cooling towers and other
air handling equipment, such as a building's ventilation system. Biofilm may be the growth
media for L pneumophila bacteria, as well as other airborne infectious bacteria.

3.2.5   Concerns for the User

The Occupational Safety and Health Administration's guidelines for the use and storage of C1O2
is available at www.osha-slc.gov/SLTC/beaUhguJdelines/chlorinedioxide/recognition.html.

Chlorine dioxide is a severe respiratory and eye irritant and therefore must be handled with great
care.  Protective clothing such as gloves should be worn at all times while handling liquid
chlorine dioxide.
                                          39

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Because aqueous chlorine dioxide is essentially gaseous chlorine dioxide in solution, there exists
the safety hazard of C1O2 volitization.  It is important that the C1O2 generation system be
equipped with safety features designed to prevent the concentration of chlorine dioxide from
exceeding its solubility limit (Simpson, undated).

3.2.6   Availability of the Technology for Commercial Applications

There are numerous commercial vendors for the supply of C1O2. Data for domestic and foreign
manufacturers of chlorine dioxide gas  generators and liquid stabilized C1O2 are presented in
Section 5.1  of mis document in the discussion of gaseous chlorine dioxide.  In addition to C1O2
generators,  some of these vendors also offer stabilized chlorine dioxide (SCO) products, such as
Radicate. Radicate is available in concentrated form for $50/liter (makes about 2 gallons).
flUtp://www.neways.com/usa/products).

The cost of generating aqueous chlorine dioxide from chlorine dioxide gas is dependent upon a
number of factors, including the price  of the generating equipment and the base chemicals used.
The cost of generating chlorine dioxide using sodium chlorite is estimated as approximately two
to four times higher than the cost of generating chlorine dioxide from sodium chlorate (a raw
material used for extremely large scale production of chlorine dioxide).  The estimated cost of
generating  one metric ton of chlorine dioxide using sodium chlorate ranged from $1,100 to
$1,800 in 1992 (Kirk-Othmer, 1993).

3.2.7   Advantages and Disadvantages

Advantages of using aqueous C1O2 in remediation operations include the following:

•      It has been shown to be effective in other applications, specifically water distribution
       system disinfection
•      It is easily applied (i.e., applied directly to the surface to be disinfected with a sponge or
       mop).
•      It is effective in relatively low  concentrations; thereby, presenting less of an occupational
       hazard during use.
•      It is quick acting.

Disadvantages of using aqueous C1O2  in remediation operations include the following:

•      There is a potential for bleaching of surfaces to which it is applied.  Weaver-Meyers et al.
       (2000) reported that a <0.02 percent (<200 ppm) aqueous chlorine dioxide solution used
       to repeatedly wipe moldy books in the University of Oklahoma Libraries had a slight
       bleaching effect on the spines of the books. Items wiped once showed no detrimental
       effects.
       The chemical is unstable.  Once prepared, the solution must be used quickly and it is
       likely that certain conditions (e.g., sunlight) would accelerate its decomposition.
•      Chlorine dioxide is not effective on porous surfaces. The March 2002 crisis exemption
       was issued for non-porous surfaces only.
                                           40

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3.2.8   Potential Areas for Future Research

Areas for potential research specifically regarding the use of aqueous chlorine dioxide in
remediation operations include the following:

•      Although the effectiveness of aqueous chlorine dioxide to decontaminate biological
       agents has been widely investigated, there are no demonstrations of the use of aqueous
       C1O2 against chemical contaminants (agents).
•      A data gap exists regarding the use of aqueous C102 against Bacillus anthracis spores.
       Currently, the susceptibility of B. anthracis spores to aqueous C102 is based on its
       biological similarity to other species of Bacillus which have been the subject of
       experiments. There is a need for systematic testing to quantify the sensitivity of B.
       anthracis to C1O2 disinfection specifically, as a function of concentration and exposure
       time. Likewise, the product's efficacy against other biological threat agents could be
       studied.
•      Further testing is needed to better determine the effectiveness of aqueous chlorine
       dioxide on non-porous materials.

3.2.9   References for Section 3.2

AO AC, 2000. Official Methods of Analysis, 17th ed.: Method 966.04.  AO AC International,
Gaithersburg, MD.

Chauret et al., 2001. Chauret, Christian P.; Radziminski, Chris Z.; Lepuil, Michael; Creason,
Robin; Andrews, Robert C. "Chlorine Dioxide Inactivation of Cryptosporidium parvum Oocysts
and Bacterial Spore Indicators." Applied and Environmental Microbiology, 67 (7): 2993-3001
(2001).

EPA, 2001. Memorandum. FIFRA Crisis Exemption for Anthrax Incidents.  From Marianne
Lament Horinko, OSWER, to Stephen L. Johnson, OPPTS. November 9, 2001.

EPA, 2002. Memorandum. Amendment of Crisis Exemption Declaration for Use of Chlorine
Dioxide (Aqueous) to Decontaminate Structures and Other Property That have Been
Contaminated or Potentially Contaminated by Bacillus Anthracis. From Marianne Lament
Horinko, OSWER, to Stephen L. Johnson, OPPTS.  March 28, 2002.

Griffith et al., 1999.  Griffith, David B.; Mainz, Eric L.; and Etherington, Roger E.  Chlorine
Dioxide as an Effective Antimicrobial Pesticide for Sanitation and Disinfection. Vulcan
Chemicals, Birmingham, AL (1999).
http://www.vul.com/vtilchemica]s/products/pdf/tds/sodiumch/600-601.pdf. Accessed November
2004.

Harakeh et al., 1988. Harakeh, S.; Illescas, A; and Matin, A.  "Inactivation of Bacteria by
Purogene." Journal of Applied Bacteriology, 64: 459-463 (1988).
                                          41

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Kirk-Othmer, 1993, Encyclopedia of Chemical Technology, Fourth Edition, "Chlorine Oxygen
Acids and Salts (C1O2, HC102)," p 977.

Krysinski et al., 1992. Kiysinski, E.P.; Brown, L.J.; Marchisello, T.J. "Effect of Cleaners and
Sanitizers on Listeria monocytogenes Attached to Product Contact Surfaces." Journal of Food
Protection,  55(4): 246-251 (1992).  •

Mayack et al., 1984. Mayack, Lynn A.; Soracco, Reginald J.; Wilde, Edward W.; and Pope,
Daniel H. "Comparative Effectiveness of Chlorine and Chlorine Dioxide Biocide Regimes for
Biofouling Control."  Water Research, 18 (5): 593-599 (1984).

Mullerat et  al., 1995.  Mullerat, Jaime; Sheldon, Brian W.; Klapes, N. Arlene. "Inactivation of
Salmonella Species and Other Food-Borne Pathogens with Salmide, a Sodium Chlorite-Based
Oxyhalogen Disinfectant" Journal of Food Protection, 58 (5): 53 5-540 (1995).

Neways, 2001. Radicate Fact Sheet. Neways, Incorporated. November 2001.

Purogene, 2003.  Chlorine Dioxide  - Purogene Product Description. ETC Products.
www.btcpfpducts,co.za/clojpurogene.asp. Accessed November 2004.

Simpson, undated. Simpson, G.D.; Miller, R.F.; Laxton, G.D.; and Clements, W.R. A Focus on
Chlorine Dioxide: The "Ideal" Biocide.  Unichem International Inc.

Tanner, 1989.  Tanner, Ralph S. "Comparative Testing and Evaluation of Hard Surface
Disinfectants." Journal of Industrial Microbiology, 4:  145-154 (1989).

Tarquin and Rittmann, 1993. Tarquin, Anthony J., and Rittmann, Douglas D. "Use of Chlorine
Dioxide for Disinfection and Taste  and Odor Control." Public Works, 124 (2):  58 (1993).

Weaver-Meyers et al., 2000. Weaver-Meyers, Pat L.; Stolt, Wilbur A.; and Kowaleski, Barbara.
"Controlling Mold on Library Materials with Chlorine Dioxide: An Eight-Year Case Study."
Abbey Newsletter, 24  (4) (December 2000).
                                          42

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3.3    Aqueous Hydrogen Peroxide

33.1   Technology Description

Hydrogen peroxide is a strong oxidizing agent.  It is commercially available in aqueous solution,
ranging in concentrations from 3 to 86 percent.  Its principal uses include wood pulp and textile
bleaching, waste and wastewater treatment, and use as a chemical intermediate (Kirk-Othmer,
1995). It is also used as a household disinfectant. It has been in use in industrial and
commercial applications for over lOOyears. Ithas been registered by EPA since 1977, as an
antimicrobial pesticide for indoor use on hard surfaces, including use in residences, medical
facilities, food establishments, and other commercial and industrial applications.

Another "peroxy" compound that is commonly used - and is often used as a supplemental
oxidizing agent in mixtures with hydrogen peroxide - is peroxyacetic acid. Peroxyacetic acid,
an organic peroxide, has been registered since 1985 as an antimicrobial pesticide for indoor use.

While hydrogen peroxide (H2O2) solution is effective as an oxidizing agent, its effectiveness
increases when dissociated into hydroxyl free radicals (i.e., OH»). For example, non-dissociated
hydrogen peroxide is not fully effective in detoxifying VX, as not all chemical bonds
contributing to the potency of this threat agent are broken by peroxide alone.  However,
hydroxyl free radicals are very effective in detoxifying VX and other chemical agents (Yang,
1999). For this reason, hydrogen peroxide is often combined with other reagents to increase its
activity and effectiveness.

Many different formulations containing hydrogen peroxide have been developed and tested on
chemical and biological agents.  This chapter will include discussions of formulations where
hydrogen peroxide is a principal reagent. As discussed below, hydrogen peroxide is often
combined with other ingredients which provide synergjstic effects in sterilant formulations. For
example, Sandia Foam (contains hydrogen peroxide and surfactants) and Decon Green (contains
hydrogen peroxide, carbonates, molybdenum, and surfactant), each discussed elsewhere in this
report, are foam formulations with hydrogen peroxide as an active ingredient.

Liquid hydrogen peroxide is identified as being much less sporicidal than the vaporized form at
low concentrations (Carlsen and Raber, 2002).  Nevertheless, data are available regarding the
effectiveness of liquid hydrogen peroxide on its ability of detoxifying both chemical and
biological agents.

In detoxifying small quantities of chemical agents or agent-contaminated surfaces, a liquid
solution containing excess reagents is frequently used (Yang, 1999). The solution contains
excess reagents that chemically  convert the agent to less toxic reaction products. Hydrogen
peroxide can be used in a manner similar to other cleansing agents. The solution is applied to a
wipe (e.g., mop, sponge), spread on a surface, and allowed to stand for a period of time.  While
some hydrogen peroxide residue may be left following evaporation, removal of this residue is
not necessarily required depending on the end use application of the surface.  Hydrogen peroxide
solution may be considered practical for spot decontamination as well as for larger areas that are
well contained and easily accessible.
                                           43

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Additional reagents can be mixed with hydrogen peroxide to increase its effectiveness. For
example, ultraviolet light and metal catalysts (iron and copper) are effectively used for
promoting free radical formation in hydrogen peroxide to increase effectiveness.  Reagents such
as organic solvents and pH adjusters are needed when detoxifying chemical agents; these
reagents increase the solubility of the chemical agent in the cleaning solution and allow for more
effective contact between the hydrogen peroxide and the toxic agent Peroxyacetic acid and
similar organic acids - strong oxidizing agents in their own right - can be added specifically to
increase the oxidizing capability of the hydrogen peroxide in such solutions.

Solutions containing hydrogen peroxide may have a limited shelf-life. Hydrogen peroxide is
known to destabilize and decompose into water and oxygen over time (Kirk-Othmer, 1995). In
addition, the stability of a dilute solution such as one used for cleaning is typically less than that
of a concentrated material (Kopis, 2000). This is particularly the  case for oxidizing chemicals.
Therefore, it is expected to be more effective to dilute hydrogen peroxide solutions at the use site
rather than to purchase 'ready to use' diluted formulas.

3.3.2   Technical Maturity

There are several sterilization products on the market that contain hydrogen peroxide.  These
have applications in the food and medical industries for general hard surface cleaning of
biological organisms as well as food preparation. Some of these products are discussed in
Section 3.3.4.

Additionally, there are specialized formulations available which have been developed
specifically for building or warfare decontamination. These include, among others, Sandia Foam
and Decon Green, discussed elsewhere in this report.

Other formulations have been patented, although their applications are not known.  A mixture of
hydrogen peroxide and a bleach activator (e.g., tetra-acetyl ethylenediamine) forms a
peroxycarboxylic acid (in the same family as  peroxyacetic acid), which is a strong oxidizer. The
solution is applied to contaminated surfaces for removal of chemical agents (Brown, 2002). As
discussed later in this section, other applications of hydrogen peroxide and peroxyacetic acid are
commercially available for biological disinfection.

33.3   Applications of the Technology

The greatest application for liquid hydrogen peroxide is in the bleaching of pulp and paper.  Its
demand is due to its application as a more environmentally-friendly alternative to chlorine
compounds. In 1991; 49 percent of the total North American hydrogen peroxide demand was in
the pulp and paper market (Kirk-Othmer, 1995). By 2000, this use increased to 57 percent.
Hydrogen peroxide is  also used in textile bleaching, waste and wastewater treatment, and use as
a chemical intermediate  (Kirk-Othmer, 1995).

       Hydrogen peroxide is used as an over-the-counter biological disinfectant for indoor hard
surfaces in residential, commercial, and industrial applications.
                                           44

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33.4  Evaluation of Available Data

Performance data for aqueous solutions containing hydrogen peroxide - in detoxifying both
chemical and biological agents - are frequently available only from laboratory experiments, such
as liquid-phase chemical reaction data or test strip applications.  Data obtained from laboratory
measurements  are effective for screening or for making comparisons (Kopis, 2000). However,
there is some uncertainty in applying laboratory data towards the decontamination of surfaces in
the field; 'field test' data are the preferred indicator of performance.  Some field data for the
hydrogen peroxide-containing Sandia foam are available for a simulated building environment,
as discussed in Section 4.1 of mis document.

Based upon lab tests using the AOAC Sporicidal Activity Test, EPA has issued crisis
exemptions under FIFRA Section 18 for several aqueous products containing hydrogen peroxide,
for use in the cleaning of buildings contaminated with Bacillus anthracis (Horinko, 2002).
Some of these  products are concentrated formulations which are diluted immediately prior to use
in accordance with product instructions, while others require no dilution. Exemptions have been
issued for the following products:

       •       Oxonia Active, diluted to 2.1 percent hydrogen peroxide and 0.45 percent
              peroxyacetic acid;
       *       KX-6049, diluted to 0.7 percent hydrogen peroxide and 0.45 percent peroxyacetic
              acid;
       •       Actril Cold Sterilant and Spor-Klenz Ready to Use,- each applied as an undiluted
              formulation of 0.8 percent hydrogen peroxide and 0.06 percent peroxyacetic acid;
       •       Johnson Virex STF, applied as an undiluted formulation of 7.5 percent hydrogen
              peroxide.

As shown, these formulations include hydrogen peroxide in concentrations ranging from 0.7
percent to 7.5 percent, and peroxyacetic acid in concentrations ranging from 0.06 percent to 0.45
percent. Peroxyacetic acid (also known as peracetic acid, CH3COOOH), like hydrogen peroxide,
is an oxidizing agent.

The crisis exemption issued for each of these aqueous peroxide products specifies the conditions
under which they must be applied for treatment of B. anthracis.  All of the products must be
utilized only on hard surfaces; must be applied at room temperature (68 °F, or 20 °C); and must
have a contact  time of at least 10 to 20 minutes, depending upon the specific product.. The extent
of product dilution prior to use is also specified. Further information is available on EPA's web
site,
 wvs^w.epa.gov/Desticides/factsheets/chemicals/livdrogenperoxide peroxvaceticacid factsheetht
Performance Towards Chemical Agents

In some instances, chemical agents react to form toxic end products, depending on the reactants
used (Wagner and Yang, 2002).  For example, for VX, perhydrolysis (reaction of OOH", formed
from hydrogen peroxide) minimizes or avoids the generation of a toxic byproduct - S-[2-
(diisopropylamino)ethyl] methlylphosphonothioic acid, called EA 2192 - which is generated
                                          45

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from simple hydrolysis (reaction of OH ).  As another example, HD can be hydrqlyzed to
nontoxic thiodiglycol by simple hydrolysis (although the nucleophilic substitution is slow).
HD can be rapidly oxidized to form two reaction products, a sulfone (which has severe irritating
vesicant properties) and sulfoxide (which does not).  Hypochlorites and peroxyacids rapidly
oxidize HD, but the reaction is non-selective, producing both sulfoxide and sulfone. Hydrogen
peroxide, a milder oxidant, selectively yields the nonvesicant sulfoxide, although at a less rapid
reaction rate. The rate with hydrogen peroxide can be increased with the addition of peroxide
activators  (such as bicarbonate and molybdate), discussed further below.

The U.S. Army Edgewood Chemical Biological Center (ECBC) has examined the detoxification
of chemical agents (including VX, GB, and HD) with hydrogen peroxide (Wagner and Yang,
2002). Liquid-phase reactions of these chemical agents with hydrogen peroxide-containing
reagents were conducted in test tube experiments.  The reagents were mixtures of hydrogen
peroxide, activators such as sodium bicarbonate (to promote dissociation of the hydrogen
peroxide into more chemically-active components), and co-solvents such as t-butanol (to
increase the solubility of the chemical agent). Hydrogen peroxide concentrations ranged from
11 percent to 30 percent. Reaction speed was recorded as half-life, which is the time required
for half of the chemical agent to react (a lower half-life corresponds to higher reaction speed).
On this basis, 10 half-lives would be required to achieve a 3-log reduction, and 20 half-lives to
achieve a 6-log reduction (if reaction time is independent of the chemical agent concentration).
The results observed by ECBC are presented in Table 3.3-1.

 Table 3.3-1.  Reaction of Hydrogen Peroxide-Containing Solutions with Chemical Agents
Reagents Present (combination of peroxide,
activator, and alcohol)
15% Hydrogen peroxide and t-butanol
15% Hydrogen peroxide, 0.037M sodium
bicarbonate solution, and t-butanol
22-26% Hydrogen peroxide, 0.1M sodium
bicarbonate solution, and t-butanol
22-26% Hydrogen peroxide, 0.1M sodium
bicarbonate solution, and either ethanol, isopropanol,
or polypropylene glycol
30% Hydrogen peroxide, 0.33M sodium bicarbonate
solution, and t-butanol
11% Hydrogen peroxide, urea, 0.75M sodium
bicarbonate solution, and t-butanol
28% Hydrogen peroxide, 0.2M potassium
bicarbonate, and isopropanol/ Triton X-100 poly ether
alcohol
Observed Half-Life
VX
»16hr
120min
11 min
No data
56 sec
7.5 min
2.6 min
GB
29 days
<1 min
<1 min
No data
No data
<1 min
No data
HD
42 min
20 min
2.1 min
1.8-
1.9 min
No
data
1.6 min
2.1 min
                                           46

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Reagents Present (combination of peroxide,
activator, and alcohol)
28% Hydrogen peroxide, 0.1M potassium
bicarbonate/ 0.1M potassium carbonate, and
isopropanol/ Triton X-100 poly ether alcohol
28% Hydrogen peroxide, 0.1M potassium
bicarbonate/ 0.1M potassium carbonate/ 0.01M
potassium permanganate, and isopropanol/ Triton X-
100 polyether alcohol
Observed Half-Life
vx
<1 min
<1 min
GB
2.4 min at room
temperature; 189
min at -30 °C
«30 sec at
room
temperature; 5.7
min at -30 °C
HD
No
data
No
data
Source: Wagner and Yang, 2002.

Earlier results from ECBC examined pH variations and the use of catalysts in chemical agent
destruction with hydrogen peroxide.  Results regarding the performance as a function of pH are
shown in Table 3.3-2.  Results regarding the performance of different catalysts are shown in
Table 3.3-3.

         Table 3.3-2. Effect of pH  on VX Detoxification Using Hydrogen Peroxide
Reagent
0.5M Solution of
peroxy carbonate (sodium
carbonate and hydrogen
peroxide)
14% Hydrogen peroxide
Hydrogen peroxide and up to
6M of a strong acid such as
hydrochloric acid
pH Conditions
Slightly basic
Slightly acidic (initial pH 4)
Strongly acidic
Result of VX Detoxification
'Complete' hydrolysis of VX
in less than two minutes
Initial rapid reaction; reaction
stopped with 47% VX
remaining
Results in dissolution of VX
and subsequent detoxification
to an unspecified degree
Source: Yang, 1999.
                                          47

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    Table 3.3-3. Effectiveness of Hydrogen Peroxide and Catalysts on Chemical Agents
Chemical
Agent
HD in solution
HD in solution
VX in solution
VX or HD
Formulation
1% hydrogen peroxide in
50-50% (volume) water/
N-cyclohexyl-2-
pyrrolidinone (at 21 °C).
1 M hydrogen peroxide
(about 3 percent) in
acetonitrile (at 20 °C).
Hydrogen peroxide in
unspecified solutions
Catalyst Added
None
0.01 M vanadium
catalyst,
VO[(CH3CO)2CH J2
Iron-containing
catalysts
Result
Half-life of 6 hours
Complete
conversion < 2
minutes
"Not effective"
"Not effective"
Source: Yang etal., 1992.

Based on the data in Tables 3.3-1 to 3.3-3 and additional discussions in the source documents
(Yang, 1999; Wagner and Yang, 2002; Yang et ai, 1992), the following conclusions are
available regarding the effectiveness of hydrogen peroxide on chemical agents:

•      Most data are available for the agent in solutions or suspensions and therefore there is
       some uncertainty in extrapolating the results to a surface application.
•      Co-solvents (water soluble organic solvents) are needed to increase the contact between
       hydrogen peroxide and the chemical agent.  Chemical agents are typically insoluble in
       water.
•      Hydrogen peroxide alone, or hydrogen peroxide with a solvent, exhibits poor
       performance for the GX, HD, and VX agents.
•      Performance is significantly improved with the addition of a carbonate activator and/ or
       certain catalysts.  Various combinations resulted in a half-life of less than one or two
       minutes.  Assuming that reaction time is independent of agent concentration, a 3-log
       reduction in concentration is achieved in 20 minutes and a 6-log reduction in
      ^ concentration is achieved in 40 minutes for formulations in Tables 3.3-1 to 3.3-3 with a
       half-life of two minutes or less.
•      Activators increase the effectiveness of hydrogen peroxide.  The reaction speed increases
       for all three agents  (VX, GB, and HD) as the activator concentration increases.
•      Chemical agents react differently to activators. GB is deactivated rapidly in all
       conditions where an activator is present, and therefore is somewhat 'easier' to treat. In
       the case of VX, the fastest reaction results from the use of a mixture of potassium
       bicarbonate .and potassium carbonate.  For HD, the fastest reaction results from the use of
       a mixture of potassium bicarbonate, potassium carbonate, and potassium molybdate.
•      None of the chemical agents were tested with a commercially available hydrogen
       peroxide/peracetic acid product (or similar) such as those identified in the EPA
       exemption.  Due to their low solubility in water, however, significant destruction of these
       agents in such products would not be expected.
                                           48

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Performance Towards Biological Agents

Whereas chemical agent detoxification data are available solely from the ECBC, data regarding
the effectiveness of hydrogen peroxide towards biological agents are available from many
different sources.

One study evaluated the effectiveness of hydrogen peroxide in killing bacteria from sponges
(Ikawa and Rossen, 1999). Results from this study potentially can be used to assess the
penetrating ability of hydrogen peroxide, as well as the effectiveness of'off the shelf hydrogen
peroxide. In this study, bacteria-containing sponges were soaked for five minutes in a
commercial three percent hydrogen peroxide solution. Testing was conducted on common
household scrubber sponges. Results are presented in Table 3.3-4. The results show that a three
percent hydrogen peroxide solution has limited effectiveness in destroying certain types of
bacteria present within the sponges.  As shown, some bacteria are treated extremely effectively
while for others treatment is ineffective. In addition, hydrogen peroxide appears to have the
ability to penetrate the porous texture of a sponge.

  Table 3.3-4. Reduction of Bacteria in Sponges Following Hydrogen Peroxide Treatment
Sponge Type
Laboratory-
inoculated
household
scrubber sponge
Consumer-used
household
scrubber sponge
Bacterial
Reduction
99.998%
56.2%
Post-treatment
Bacteria Count
Not detected
(<10 CPU/
sponge)
3.2xl06 CPU/
sponge
Bacteria Type
Combination of Escherichia coli,
Salmonella choleraesuis, Pseudomonas
aeruginosa, Staphyloccus aureus, and
Shewanella putrefaciens
Bacteria resultant from day-to-day
kitchen use; species not determined
Tests conducted by soaking sponge for five minutes in a three percent hydrogen peroxide solution.
Source: Ikawa and Rossen, 1999.

The activity of a hydrogen peroxide formulation was tested by spraying solution onto glass
slides inoculated with various organisms and allowing the material to sit for two hours (Elhaik
and De Nicola, 2001). The relatively weak formulation consisted of six different individual
components, as follows: (1) hydrogen peroxide, (2) organic acid, (3) silver salt, (4) phosphoric
acid, (5) a surfactant, and (6) a corrosion inhibitor. The first three components, in combination,
provide disinfection properties. The phosphoric acid acts as a stabilizer.  Results are shown in
Table 3.3-5. The tests showed that the more concentrated solutions displayed a higher kill rate
than the less concentrated solutions. Other tests showed that the performance of the solution was
lower when either the organic acid or the silver salt was removed; hydrogen peroxide
performance improved with the addition of these components.
                                           49

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        Table 3.3-5. Performance of Hydrogen Peroxide-Containing Formulation
                               Sprayed Onto Glass Slides
Strain
Staphylococcus aureus
Psetidomonas
aeruginosa
Enterococcus faecium
Mycobacterium
smegmatis
Candida albicans
Penicillium verrucosum
Bacillus subtilis
Log Kill Rate
Solutions consisting of:
1.6 - 4% Hydrogen peroxide
1 - 2.8% acetic acid/peracetic
acid
16-25 ppm silver
16-25 ppm phosphoric acid
80-200 ppm surfactant
64-160 ppm corrosion inhibitor
6.3
6.2
5.2
5.1
5.3
5.1-5.2
3.6
Solutions consisting of:
0.8% Hydrogen peroxide
0.5% acetic acid/peracetic acid
2- 10 ppm silver
4-10 ppm phosphoric acid
20-40 ppm Surfactant
20-32 ppm corrosion inhibitor
5.2-5.3
5^1-5.2
5.1-5.2
5.1-5.2
4.2-5.0
3.8-4.1
3.6
Source: Elhaik and De Nicola, 2001.
       Note: 1% = 10,000 ppm
       Solution was allowed to set on glass slides for two hours following spray application.
       Conditions: 80% humidity, 24 °C.

A synopsis of available data regarding the effectiveness of hydrogen peroxide on B. anthracis is
available (Spotts-Whitney et al., 2003).  A 100 percent kill rate was reported for a 0.88 M (about
3 percent) hydrogen peroxide solution at pH of 4.3 to 5. Results of 100 percent kill were
reported after 3 hours for a spore suspension of 106 CFU/mL, and 100 percent kill was reported
after 6 hours for a stainless steel carrier coated with a spore suspension (initial challenge dose
not specified).

Another study examined the effectiveness of mixtures of hydrogen peroxide and other additives
towards killing viruses and bacteria (Sagripanti, 1992). These results were conducted in
suspensions.  The results showed that hydrogen peroxide alone was relatively ineffective at low
concentrations, but when combined with copper there  was a far greater degree of virus
inactivation.  Results are shown in Table 3.3-6.
                                           50

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           Table 3.3-6. Effectiveness of Hydrogen Peroxide on Biological Agents
Biological
Agent
Junin virus
B. subtilis
Hydrogen Peroxide
Concentration
1 10 mg/L (about
0.01%)
170 mg/L (about
0.02%)
5%
Other Additives
None
10 mg/L copper
0.2% copper
Result
50% reduction
3.5 log reduction
after 30 minutes
3 -log reduction after
35 minutes; >5-log
reduction after 60
minutes
Results at 21 "C.
Source: Sagripanti, 1992.

In contrast to the above apparent effectiveness of copper, one study examined the effectiveness
of hydrogen peroxide on B. globigii spores (Cross et al., 2003).  A spore suspension was exposed
to a solution of 0.1 M hydrogen peroxide (about 0.3 percent) and 0.6 M copper (11) for 30
minutes.  The tests were repeated with the addition of 0.1 M ascorbic acid. All tests using the
above mix of reagents resulted in only a 1-log kill (i.e., ten percent of the spores survived). The
reagents selected for these tests were intended to result in the formation of hydroxyl free
radicals.

Based on the above data regarding the performance of hydrogen peroxide towards biological
organisms, the following conclusions are available:

•      Most data are available for the agent in solutions or suspensions and therefore there is
       some uncertainty in extrapolating the results to a surface application.
•      A solution of 3 percent hydrogen peroxide is sufficiently effective towards destroying B.
       anthracis and several types of bacteria.  For another type of virus (Junin virus), results
       are inconclusive because a low hydrogen peroxide concentration (0.01 percent) resulted
       in low kill rate (50 percent); data for higher concentrations are not available.
•      Very effective destruction (5 to 6 logs after 2 hours) for various strains was found for
       peracetic acid/hydrogen peroxide formulations when combined with other reagents,
       including silver.  EPA evaluated confidential testing results of peracetic acid/hydrogen
       peroxide formulations on hard nonporous surfaces and issued its product-specific crisis
       exemptions, in part, on the basis of these results.
•      Metals (in particular copper and iron) have mixed results in increasing the effectiveness
       of hydrogen peroxide.  These metals have well documented effects in transforming
       hydrogen peroxide into free radicals and therefore in theory would be expected to
       increase performance.  It is possible that the degree of this increased performance
       depends on the particular organism.
i
                                           51

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3.3.5  Concerns for the User

Hydrogen peroxide is a strong oxidizer; therefore, precautions for skin, inhalation, and eye
protection are needed when handling products containing tiiis chemical in any concentration.
Most formulations for use are relatively dilute and present less of a risk than more concentrated
solutions, such as those used for vapor hydrogen peroxide. Some other precautions regarding
vapor hydrogen peroxide, as discussed in Section 5.3.5, are also applicable to liquid hydrogen
peroxide.

Significant additional shipping fees are required when purchasing any product containing
concentrated hydrogen peroxide. Hydrogen peroxide in concentrations of 8 percent or more
requires hazardous material shipping. Solutions containing hydrogen peroxide at concentrations
less than this may or may not require hazardous material shipping designation depending on the
other ingredients present.

3.3.6  Availability of the Technology for Commercial Applications

Many different hydrogen peroxide-containing products are on the market. In addition, hydrogen
peroxide alone can be purchased. The availability and cost of several of these alternatives are as
follows:

•      Actril Cold Sterilant (supplied by Minntech). This formulation contains 0.8 percent
       hydrogen peroxide and 0.06 percent peracetic acid..  Based on 2003 correspondence with
       the supplier, the cost for a case of four 1-gallon containers is $70.70 (with test strips
       included) or $51.25 (for the formulation only).
•      Concentrated hydrogen peroxide (many suppliers  possible). This is technical grade 35
       percent hydrogen peroxide.  Based on a supplier's 2003 web page (Clyde Co-Op), the
       cost for a 1-gallon container is $49.38. (As discussed in Section 5.3, this is the
       concentration used for vapor hydrogen peroxide applications.)

Several of the formulations described in Section 3.3.4 have uncertain availability. For example,
combinations of hydrogen peroxide, carbonates, and metals were prepared using the individual
chemicals. While these chemicals are readily available, it is  inconvenient and probably
impractical to prepare such formulations at a use site.

3.3.7  Advantages and Disadvantages

A principal advantage for hydrogen peroxide is that it breaks down into environmentally benign-
products — water and oxygen. As a liquid solution, it is easy to apply (e.g., sponge, mop,
spray). Another advantage cited for liquid hydrogen peroxide is that it does not freeze under
most conditions.  However, at low temperatures, the reaction time is slowed considerably
(Wagner and Yang, 2002).

Hydrogen peroxide is a an oxidant; therefore, it is expected to detrimentally affect color in
textiles, carpet, etc. In addition, its effectiveness towards porous materials, such as textiles and
carpets, has not been demonstrated.
                                           52

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 Like other liquid phase decontaminants and sterilants, the surface must remain wet for the active
 ingredient to be efficacious against the target organism. In addition, for most products, the
 surface to be treated should be pre-cleaned. The correct concentration, contact time, and
 temperature for application of each product are determined by the results of the efficacy testing
 for that product.

 The effectiveness of hydrogen peroxide in destroying G agents, such as GB, is identified as
 about equal to the performance of an unmodified base solution (e.g., of NaOH), having a pH just
 above 7.  For the G agents, there is little advantage to using hydrogen peroxide. However, for
 VX, the use of base solutions result in the formation of a toxic byproduct, which does not result
 from the use of hydrogen peroxide (Wagner and Yang, 2002).

 3.3.8   Potential Areas for Future Research

 Additional data are desirable in several areas.  More data regarding the effectiveness of hydrogen
 peroxide and/or peracetic acid is desirable, particularly  with regard to porous and nonporous
 surfaces. There may be difficulties in the practical building decontamination application of
 some of the peroxide formulations that have been found to be effective in the lab. Therefore,
 formulations or on-site recipes may need further development

 3.3.9   References for Section 3.3

 Brown, 2002. Brown, Jerry S. Chemical and Biological Warfare Decontaminating Solution
 Using Bleach Activators. U.S. Patent No. 6,369,288. April 9,2002.

 Carlsen and Raber, 2002. Carlson, Tina; and Raber, Ellen. "The Use of Vaporous Hydrogen
 Peroxide for Building Decontamination." CBNP 2002 Summer Meeting Abstracts, pp 43-44.
 July 30, 2002.

 Cross et al., 2003. Cross, J.B.; Currier, R.P.; Torraco, D.J.; Vanderberg, L.A.; Wagner, G.L.;
 and Gladen, P.O. "Killing of Bacillus Spores by Aqueous Dissolved Oxygen, Ascorbic Acid,
 and Copper Ions." Applied and Environmental Microbiology, 69 (4): 2245-2252 (2003).

 Elhaik and De Nicola, 2001.  Elhaik, Alain; and De Nicola, Raphael Alex. Aqueous
 Composition Containing H2O2, Acids andAg, Preparation Method Therefor and Use Thereof for
 Disinfection, Hygiene and/or Pollution Control. U.S. Patent No. 6,277,414.  August 21, 2001.

 Horinko, M.L.  2002.  Memoranda to Stephen L. Johnson, regarding FIFRA Crisis Exemption
* for Anthrax Incidents. February 14, 2002; March 28, 2002; June 25, 2002.

 Ikawa and Rossen, 1999. Ikawa, Judy Y.; and Rossen,  Jonathan S.  "Reducing Bacteria in
 Household Sponges."  Environmental Health, July/August 1999, pp 18-22.

 Kopis, 2000.  Kopis, E.M.  "Surface Decontamination:  Selection, Control, and Validation of
 Cleanroom Sanitizing Agents." Pharma + Food International,  2000, pp 66-69.
                                           53

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Kirk-Othmer, 1995. Encyclopedia of Chemical Technology, Fourth Edition, Volume 13.
"Hydrogen Peroxide".

Sagripanti, 1992. Sagripanti, Jose-Luis.  "Metal-Based Fonnulations with High Microbicidal
Activity." Applied and Environmental Microbiology, 58 (9): 3157-3162 (1992).

Spotts-Whitney et al., 2003. Spotts-Whitney, Ellen A.; Beatty, Mark E.; Taylor Jr., Thomas H.;
Weyant, Robbin; Sobel, Jeremy; Arduino, Matthew J.; Ashford, David A.  "Inactivation of
Bacillus anthracis Spores." Emerging Infectious Diseases, 9 (6). 2003.

Wagner and Yang, 2002.  Wagner, George W.; and Yang, Yu-Chu. "Rapid Nucleophilic/
Oxidative Decontamination of Chemical Warfare Agents." Industrial Engineering and
Chemistry Research, 41: 1925-1928 (2002).

Yang, 1999.  Yang, Yu-Chu. "Chemical Detoxification of Nerve Agent VX." Accounts of
Chemical Research, 32: 109-115 (1999).

Yang et al., 1992. Yang, Yu-Chu; Baker, James A; Ward, J. Richard.  "Decontamination of
Chemical Warfare Agents." Chemical Reviews, 92:  1729-1743(1992).
                                         54

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3.4    TechXtract® Contaminant Extraction Technology

TechXtract is a decontamination technology that chemically extracts hazardous substances from
solid materials such as concrete, brick, steel, and wood.  It is a proprietary process with a
proprietary set of chemical mixtures used for treatment.  TechXtract is designed to remove
organics, metals, or radionuclides from the surface and subsurface of porous and nonporous solid
materials in a series of application, penetration, and extraction steps.

3.4.1   Description of the Technology Alternative

Environmental Extraction Technologies, Inc. (EET) is a division of Active Environmental
Technologies, Inc. (ACT). EET calls their TechXtract a "contaminant extraction technology".
The technology can be used for treating floors, walls, ceilings, and equipment. The mixtures
may include emulsifiers, buffered organic and inorganic acids, and hydrotropic, electrolyte,
flotation, wetting, and sequestering agents that extract the contaminants and bring them to the
surface. The chemical mixtures are applied sequentially, in successive cycles. Each treatment
cycle includes application, penetration, and extraction. Wet vacuuming is used to remove the
solutions from the treated substrate.

Effective decontamination of a porous surface is one of the more challenging aspects of building
decontamination. TechXtract's effectiveness in decontamination of porous surfaces is, in part,
because it uses wetting agents to increase permeation into pores, and because it uses wet
vacuuming to get treatment solutions back out of pores.

Although TechXtract is a proprietary process, EET describes the types of chemicals used in their
process generically in their advertising literature and on their Internet web site. More detail on
specific chemicals used in TechXtract formulations is provided in their patents (Borah, 1995,
1996,1998; Tyerech, 1998).

How TechXtract Is Used

EET uses and sells chemical formulations called TechXtract 100, 200, and 300.  TechXtract 100
is used in one type of treatment cycle. It contains macro- and micro-emulsifiers, as well as
electrolyte, flotation, wetting,  and sequestering agents. It is applied to the surface being treated
as a fine mist, then worked into the surface using an abrasive pad. Then the TechXtract is
allowed at least 45 minutes to penetrate into the subsurface.  A rinse formula, often percent
TechXtract 300 mixed with water, is sprayed onto the surface being treated. Then the treatment
chemicals and contaminants are removed using a wet vacuum.

The other type of treatment cycle uses TechXtract 200 and 300, and often follows a TechXtract
100 cycle.  TechXtract 300 is  applied first, and worked into the surface using an abrasive pad.
Then TechXtract 200 is immediately applied using the same procedure. EET claims mat
TechXtract 200 and 300 work together synergistically. They  contain buffered organic and
inorganic acids, sequestering agents, wetting agents, and hydrotropic chemicals.
                                           55

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The number of TechXtract 100 and 300/200 cycles used for a given decontamination situation
will depend on the contamination levels, the difficulty of removal of the contaminant from the
matrix, and the depth of the contamination.

TechXtract formulations are applied with abrasive scrubbing, such as with a scrub brush,
abrasive pad, or electric floor polisher. This helps remove surface contamination, allowing
access by the formulations to the subsurface, and mechanically enhancing penetration.

TechXtract usually solubilizes and extracts, rather than  destroying the target compound.
Therefore, the liquid wastes contain the extracted contaminants, and must be discarded. In some
cases, oxidizing agents are used in the formulations, in which case oxidation products are
produced as secondary waste.  Small amounts of the TechXtract chemicals are likely to remain
in the treated matrix, especially if the matrix is porous.  EET says that none of the TechXtract
constituents, when spent, will be characterized as hazardous wastes under the Resource
Conservation and Recovery Act (RCRA).

By  design, a very small amount of the substrate is leached or removed by TechXtract to facilitate
release of contaminants. This may result in an unacceptable effect to the surfaces of expensive
or sensitive materials.

Functions of the TechXtract Formulation Components

The chemical warfare agents and industrial chemicals most likely to be used in a terrorist
scenario would probably be organic chemicals. Therefore, the functions of the treatment
chemicals used in TechXtract formulations are discussed here in the context of remediating
buildings contaminated with hazardous organics.

Emulsifiers are surface-active chemicals that, in TechXtract applications, stabilize suspensions
of organics (having low aqueous solubility) in aqueous  matrices.  They perform like detergents.
The emulsifiers mentioned by EET in their patent for removal of contaminants from surfaces
were quaternary  amines.

Flotation agents  are another type of surface-active chemical, that will cause solid metal-
containing particles to adhere to air bubbles and float to the surface of liquids. They would be
most useful for heavy metal or radionuclide removal from a contaminated matrix. They would
also help to open up an inorganic matrix (such as concrete, brick, or stone) to allow organics
extraction.  Flotation agents are widely used in the mining industry, for separation of metal-
containing ore particles from the low metal content ore  tailings.

Wetting agents are another type of surface-active chemicals used in TechXtract formulations.
They decrease the surface tension of aqueous solutions, enhancing their ability to penetrate into
small pores and crevices. This would be expected to greatly increase the decontamination
effectiveness of TechXtract formulations for porous matrices such as concrete and wood.
Wetting agents are used in agriculture, where they are called soil penetrants, because they
enhance the permeation of beneficial  chemicals (nutrients and pesticides) through the soil matrix
to the plants' roots, where they can be most effective.
                                           56

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Sequestering agents are chemicals that form complexes or chelates with metals, enhancing the
extractability of the metal by aqueous formulations. When removing organic contaminants from
metal surfaces, and from the boundaries between metal grains in a metal object, sequestering
agents will dissolve small amounts of the metal surface, releasing the organics to the extractant
formulation and enhancing their removal. Sequestering agents are widely used for cleaning
metal surfaces, and for solubilizing  nutrient metals for plants in the horticultural and agricultural
industries.  TechXtract patents mention a variety of sequestering agents, including nitrilotriacetic
acid, hydroxyethylene diamine tetraacetic acid, and ethylenediamine tetraacetic acid (EDTA).

Buffered organic and inorganic acids have at least three purposes.  They release contaminants
from metal surfaces by dissolving some of the metal, analogous to sequestering agents.
Ammonium bifluoride, which releases hydrofluoric acid in aqueous solution, is used
commercially to remove vitreous  enamel  from metal surfaces.  Its ability to solubilize silica and
silicate matrices is probably why it is used in TechXtract formulations.  Stone, brick, and glass
are silica and silicate types of building materials whose decontamination would be enhanced by
ammonium bifluoride to dissolve  their surface and open the matrix. Some polyfunctional
organic acids used in TechXtract, like oxalic acid and citric acid, are also sequestrants.  (Oxalic
acid is used commercially to remove rust stains.) Organic acids with aliphatic hydrocarbon
chains will also act as co-solvents for organic contaminants and for organic emulsions of
contaminants. (See hydrotropic chemicals.) The buffering of the acids helps control the amount
of metal that is removed from a surface, so that damage to the surface is minimal or negligible.

Hydrotropic chemicals (also known as co-solvents) increase the solubility of other chemicals in
water-based solutions. They typically have both hydrophilic and hydrophobic components in the
same molecule,  similar to surfactants, but they form solutions rather than suspensions. Ethylene
glycol monobutyl ether and glycerine are examples of hydrotropic chemicals used in TechXtract
formulations.

Electrolytes may be contained in TechXtract formulations. In its patents, EET makes it clear
that de-ionized or distilled water is used in its formulations, to minimize ions in solution that
would decrease  the effectiveness of the formulations.  Tap water tends to contain variable levels
of cations, such as the divalent cations magnesium and calcium, which use up the sequestrants.
Salts in solution can decrease the  effectiveness of the nonionic surfactants in emulsifying target
organics. In some cases, however, EET uses monovalent cations (such as Na+) to disrupt the
links between matrix divalent cations (such  as Ca++ and Mg++) and contaminants, to separate
contaminants from surface charged matrices such as concrete or clays (SAIC, 2003).

It is apparent that TechXtract formulations draw on a wide variety of surface cleaning, and
contaminant solubilization and mobilization technologies that have been individually proven in
other industries. Their integration into a single decontamination technology, or array of
decontamination formulation variants, by EET is one of the innovative aspects of TechXtract.
The ability of TechXtract formulations to penetrate into porous surfaces by using wetting agents,
and the wet vacuuming to get treatment solutions back out of pores, are the other most
significant innovations of this technology.
                                          57

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3.4.2  Technical Maturity

TechXtract is an array of technologies that have been integrated into commercial
decontamination service.  Some elements of the technology, such as the use of surfactants in
aqueous solutions to remove organic contaminants, and the use of chelating agents to remove
heavy metal contaminants, are mature technologies, used widely in industry for decontamination
applications.  Other elements of TechXtract, such as the use of Teuton's reagent, wetting agents,
ammonium bifluoride, monovalent cations, and flotation agents  for decontamination applications
are less mature elements of decontamination technology. These technologies are mature for
other industrial applications, but their use in building decontamination is innovative and less
mature.

None of the decontamination projects performed with TechXtract have involved chemical
warfare agents (CWAs). Because most applications of the technology have been removals rather
than in-place chemical destructions, and many of the successful applications have been the
removal of difficult hydrophobic organics, there is little question that TechXtract will be able to
remove VX, HD, and the G-agents from a variety of building material substrates.  The CWAs
would then have to be treated and disposed as hazardous waste.

Some of the acidic ingredients used in TechXtract formulations  might hydrolyze CWAs in place.
If the Fenton's reagent version of TechXtract were applied to CWAs, which uses hydroxyl
radicals and ozone to oxidize contaminants, it is likely that the CWAs would be, at least
partially, destroyed in place (converted to much less toxic products).  These applications have
not been tested; there is no assurance of their success (See section 3.4.8).

The simplicity of the application and removal of TechXtract formulations to and from a substrate
to be decontaminated, in multiple stages depending on the difficulty of the task, makes the
technology readily scalable to large and small tasks.  The cost per unit area of the
decontamination task will be higher for small areas than for large areas, because the cost for
mobilization is a relatively fixed cost. For tasks over about 5000 ft2, the material and labor costs,
which are proportional to the size of the cleanup, will be the dominant costs (see section 3.4.6).

3.4.3  Applications of the Technology

The TechXtract array of decontamination technologies is fully commercialized. It is available as
a service performed on site by EET, or as a  commercially available set of products, with training
services available as well (see section 3.4.6).

EET claims to have used TechXtract decontamination in over four hundred applications, with a
99 percent success rate (EET, 2004). It has been applied to removal of organics from concrete
and granite floors and large metal equipment, which are target applications relevant to terrorist
contamination of buildings.
                                           58

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TechXtract was tested by the Hanford Site C Reactor Technology Demonstration Group, under
the auspices of the U.S. Department of Energy's (DOE's) Federal Energy Technology Center,
for 1he removal of radionuclide contamination from the surface of lead bricks (DOE, 1998).

3.4.4  Evaluation of Available Data

The following paragraphs describe two decontamination projects performed with the TechXtract
technologies that illustrate its applicability to building cleanups.

Potychlorinated Biphenyl (PCS) Transformer Oil Extraction from Concrete Floor in Building

The TechXtract technology was tested under the EPA's Superfund Innovative Technology
Evaluation (SITE) Program in 1997 for removal of PCBs on concrete (U.S. Navy, 1997; EPA,
1998). The following paragraphs describe the test

A field demonstration of TechXtract was performed under the SITE Program, in cooperation
with the U.S. Navy's Pacific Division of the Naval Facilities Engineering Command (PACDIV)
and the Pearl Harbor Public Works Center (PWC), at the Pearl Harbor Naval  Complex on Oahu,
Hawaii.  A concrete floor, 124 square feet in area, was contaminated with PCBs and oils,
including a 14 square foot area of high PCB concentrations and visible staining. The
demonstration was performed during February and March, 1997..

Pretreatment wipe samples, of 100 cm2 areas of the surface, showed PCB levels of 10,000 to
32,000 ng/100 cm2. Pretreatment concrete core samples showed up to 3.5 percent subsurface
PCBs, including as high as 2.5 percent at 2 to 4 inches below the concrete surface.

PWC  staff performed the decontamination, after having been trained by EET staff. Twenty
TechXtract 100 and twelve TechXtract 300/200 cycles were applied to the PCB contaminated
concrete floor.

The significant ability of TechXtract to remove surface PCBs is indicated by the wipe sample
data in Table 3.4-1. For the three most contaminated surface locations (where PCBs were
10,000 ^ig/100 cm2 or greater), the contaminant removal efficiency was 99.5 to 99.8 percent. For
the other thirteen surface locations with PCB levels below 1000 ng/100 cm2, the removal
efficiency was between 81 and 99.7 percent.

The subsurface decontamination effectiveness of TechXtract was variable, and the data show
that the technology is not as effective as  it is for surface  contamination. Table 3.4-2 shows data
indicating significant PCB removal at only one of five coring locations (C3).  The other four sets
of coring results (locations Cl, C2, C4, and C5) indicate that subsurface contamination was
unchanged or increased during the decontamination process.
                                         59

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Table 3.4-1. Surface PCS Removal Based on Wipe Samples
Location
Wl
W2
W3
W4
W5
W6
W7
W8
W9
W10
Wll
W12
W13
W14
W15
W16
Total PCBs (ug/100 cm2)
Pre-Treatment
11
32,000
140
39
28
41
10,000
940
47
17
32
40
35
11,000
290
85
Post-Treatment
1.6
79
11
1.5
5-4
1.5
48
6.4
1.3
2.3
3.9
<1.0
<1.0
34
<1.0
12
Change
- 85%
- 99.8%
- 92%
- 96%
- 81%
- 96%
- 99.5%
- 99.3%
- 97%
- 86%
- 88%
- 98%
- 97%
- 99.7%
- 99.7%
- 86%
  Table 3.4-2. PCB Removal at Depth Based on Corings
Location
Cl
C2
C3
C4
C5
Depth Below
Surface (inches)
0-1
1-2
2-4
0-1
1-2
2-4
0-1
1-2
2-4
0-1
1-2
2-4
0-1
1-2
2-4
Total PCBs (ug/g)
Pre-Treatment Post-Treatment
32,000
22,000
15,000
35,000
29,000
25,000
14,000
33,000
24,000
3,400
12,000
. 13,000
4.80
0.11
0.48
30,000
19,000
16,000
27,000
30,000
21,000
330
39
120
29,000
17,000
13,000
26
9.1
6.2
Change
-6%
-14%
+6%
-23%
+3%
-16%
-98%
-99.9%
-99.5%
+850%
+140%
0%
540%
830%
130%
                        60

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Figure 3.4-1 shows where the wipe and coring samples were
collected.  All of the coring samples were collected in or near
the oil stained area, which is probably where the
contamination was heaviest. Although EET did not analyze
for oils other than PCBs, it is quite possible that the concrete
was more organics saturated man the PCB data alone suggest.
This would have made subsurface decontamination more
difficult. The surface decontamination results are much more
indicative of how TechXtract would perform in a building
decontamination following a terrorist chemical attack.

The following section describes the use of TechXtract to
decontaminate a large piece of equipment that had been
contaminated with PCBs, polychlorinated dibenzo-p-dioxins
(PCDDs), and polychlorinated dibenzofurans (PCDFs).

Removal ofDioxin Contamination for Gas Turbine
Generator Set Repair
 ' 5JYf"'* """"*"* T 77 "7" ""'" "V""" yS-T"1!-" ;'>'^^A'*.W.W.MA'VK
 V'.'~:!v,:,v"-X'-X •.'•'• f'•'•'•'•''•'•:'>>* ".''".-'/.'I.,':';','. ;.j.~;;O"•)-;"'.":.'>'-;

 t:-::::r'iV.i;|;^|;^;Ei?;;^;.;:-v:^
 ^^i^Fl^^^p
 -,•::.(-,.:, :-.'^'~: r?M.. •••: S^SK .:::.*;:
Figure 3.4-1. Locations of
Wipe and Coring Samples
On October 6,1997, an explosion and fire in Independence, Missouri at the Power and Light
Department Gas Turbine and Electrical Substation No. 1 damaged and contaminated a large gas
turbine generator. The generator needed to be repaired, but first it had to be decontaminated.
One of two transformers at the substation had exploded, producing a fire that caused capacitors
to rupture also.  Wipe samples of the generator showed that it had been contaminated with PCBs,
and with PCDDs and PCDFs that had been produced by the fire. Hexane wipe samples showed
surface levels of PCDDs and PCDFs [in 2,3,7,8-tetrachloro-dibenzodioxin (TCDD) equivalents]
in the range of 3.1 to 24,800 ng per m2.  The cleanup goal for the generator for PCDDs and
PCDFs, so that it could be safely repaired, was 25 ng/m2.

A contractor was hired to decontaminate the generator and, despite multiple passes with "widely
recognized non-polar solvents," the cleanup target was not achieved. Leach-back, which EET
describes as the increase of contaminant levels over time after surface cleanup goals are reached,
caused the concentrations to return to failing levels again.  (Although the leach-back
phenomenon  might be expected in a porous material, Scott Fay of Active Environmental
Technologies has indicated that the crystal boundaries of a metal can also hold contamination,
leading to leach-back (SAIC, 2003).

EET was then contracted to perform the decontamination of the generator.  EET recognized the
significantly hydrophobic nature of PCDDs and PCDFs. To facilitate the water-based
TechXtract decontamination process, an oxidation step was added to the cleanup process.  The
Fenton reaction, which produces strongly oxidizing hydroxyl radicals and ozone, was used to
partly oxidize the PCDDs and PCDFs, making them more polar and more soluble.

Final concentrations of PCDDs/PCDFs are summarized in Table 3.4-3, which compares cleanup
levels with initial contaminant levels. A minimum of 96 percent contaminant removal was
achieved, and the cleanup goal was achieved.
                                          61

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    Table 3.4-3. Gas Turbine Generator PCDD/PCDF Wipe Samples Before and After
Sample
Designation
001TEWS
002GEWS
006LLT
007PAF
009RRW
010RRE
016LGE
017LGT
018LGCE
023SPI-2
Sample Name
Turbine end plate,
winding side
Generator end plate,
winding side
Lead line tunnel
Plenum air flow
W side retaining ring
East side RR
Load gear, East
Load gear, Top
Load gear coupling, East
South end of pedestal
inside wall
Initial
Concentration
(ng/m1)
44.48
63.4
544.4
24,788.
4769.
3548.
45.21
21.35
35.02
' 3.1
Final
Concentration
(ng/m2)
0.014
0.0053
0.39
. 0.067
0.00
0.00
0.00
0.00
0.00
0.12
Change in
Concentration
- 99.97%
- 99.99%
- 99.93%
- 99.9997%
> - 99.9999%
> - 99.9999%
>- 99.99%
> - 99.98%
>- 99.99%
-96%
3.4.5  Concerns for the User

Although TechXtract formulations can contain a variety of organic and inorganic acids, and
.organic solvents, EET claims that their spent solutions would not be RCRA characteristic
hazardous waste. However, the spent solutions will take on the characteristics of the
contaminant that is removed.  These are some of the ingredients in TechXtract formulations that
necessitate careful handling, based on EET's Material Safety Data Sheets:
              Sodium hydroxide, 1-5 percent
              Ammonium bifluoride, less than 1 percent
              Phosphoric acid, 1 percent
              Nitric acid, 1-5 percent
              Ethylene glycol monobutyl ether, 5-15 percent
When TechXtract formulations are handled, appropriate personal protective equipment (PPE)
should be worn, including the following:
              Organic solvent resistant impermeable gloves
              Splash apron or rain gear
              Face shield
              Organic solvent resistant impermeable boots.
                                          62

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Other PPE may be required, for protection against the contaminants being removed based on a
hazard assessment of site-specific conditions as documented in a Health and Safety plan.

Most TechXtract formulations are fairly stable on storage at ambient temperatures. Only the
oxidizer-containing formulations are expected to have a limited life, because of the peroxide-
forming compounds they contain. Their room temperature life expectancy (retaining 70 percent
potency) is about 40 weeks to one year.

3.4.6. Availability of the technology for commercial applications

EET claims to have used TechXtract decontamination in over four hundred applications, with a
99 percent success rate (EET, 2004). It has been applied to removal of hydrophobic organics
(PCBs, PCDDs, PCDFs) from concrete and steel surfaces, radionuclides from lead surfaces,
organic lead from concrete and granite, inorganic lead and mercury from concrete, and tritium
from concrete.

TechXtract Commercial Products and Services

EET provides decontamination services, and provides training to other companies who want to
perform their own decontamination.

EET will also provide training on how to perform TechXtract decontaminations.  They will sell
TechXtract formulations, customized for a particular cleanup. The formulations sell for $35 per
gal in 55-gal quantities.

Decontamination services are provided by EET, including equipment, formulations, and trained
staff (technicians and supervisor). EET's average cost for cleanup and disposal of PCBs
(hydrophobic organics), for jobs over 5000 ft2, is about $4.50/ft2.

For a PCB cleanup, with relatively uniform surface contamination of about 10,000 ^g/100 cm2,
EET estimates the cleanup price to be $5 to $6/ft2. This assumes seven to eight treatment cycles.
Factors increasing the cost of cleanup include:
             Spoiled (not smooth) concrete surfaces (about 10 percent increase)
             Walls and ceilings (about 25 percent increase compared to floors)
             Cold temperatures (40 °F cleanups cost about 20 to 30 percent more than 70 °F
             cleanups)
             More hydrophobic organics
             Higher contamination levels
             More stringent cleanup concentration goals
             Coated surfaces
             Deep contamination (up to 4 inches).
                                          63

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3.4.7  Advantages and Disadvantages

TechXtract has advantages and disadvantages for building decontamination.  These are
summarized in the following two sections.

Advantages of TechXtract

The TechXtract technology was designed with minimization of secondary wastes as a design
criterion. The treatment formulations tend to be concentrated, and are applied by hand,
minimizing their volume. Minimal amounts of rinse solutions are also used,  and their removal is
enhanced by wet vacuuming. EET often prices cleanups with the disposal of secondary waste
included, giving EET an incentive to minimize the wastes requiring disposal.

Application of the TechXtract technology is relatively simple, and the techniques are not
proprietary (though the formulations are). The technology is simple enough that EET will train a
company's own staff to use it.

TechXtract can be used to clean solid matrices relatively deeply - up to 4 inches for concrete, for
appropriate levels of contamination. This is a particularly innovative aspect of the technology.
Most other competing in-place chemical decontamination technologies are only effective for
surfaces.

TechXtract is applicable, with the appropriate formulations, to a wide variety of decontamination
problems:

       •      Hydrophobic organics
       •      Heavy metals
       •      Organometallics
       •      Radionuclides
       •      Mixed waste (organics and radionuclides together).

Disadvantages of TechXtract

There are some disadvantages to the use of the TechXtract technology.  The surfaces of treated
matrices are abraded and dissolved away to some degree.  Concrete surfaces that have been
decontaminated with TechXtract are much more intact, however, than after spalling. Inorganic
fluorides, which are relatively toxic at elevated levels, are used in some TechXtract
formulations.

The TechXtract formulations are proprietary, so there is a cost that is greater than the raw
materials might be. The selection of formulation ingredients is done by EET based on the
specific application, the contaminants, and the matrix to be decontaminated.

TechXtract has not been tested for effectiveness in decontamination of CWAs from building
surfaces or equipment.  Its  effectiveness can only be extrapolated from its performance in
           *
                                          64

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extracting hydrophobic organics from building and equipment surfaces. These data, presented in
section 3.4.4, suggest that TechXtract would be effective.

3.4.8   Potential Areas for Future Research

The application of the TechXtract technology to clean up building components contaminated
with CWAs needs to be laboratory and field tested. VX, a hydrophobic organophosphate, or an
analogous compound should be tested first.  TechXtract has demonstrated its effectiveness for
removal of other hydrophobic organics. Nest, mustard, and a G-agent such as  GB, should be
tested.  These may be removed fairly readily; their degree of destruction by TechXtract
formulations should also be measured. Thorough study of TechXtract effectiveness for CWAs
would also include tests on both minimally porous surfaces like steel, on painted surfaces, and
on porous surfaces such as concrete and wood.

Section 3.4 References

Borah, 1995. Borah, Ronald E.  Methods for removal of contaminants from surfaces. U. S.
Patent No. 5,421,906.  June 6,1995.

Borah, 1996. Borah, Ronald E.  Precleaning fluids for use in a process for the removal of
contaminants from surfaces. U.  S. Patent No.  5,512,202. April 30, 1996.

Borah, 1998. Borah, Ronald E.  De-scaling solution and methods of use.  U. S. Patent No.
5,821,211. October 13,1998.

DOE, 1998. Lead TechXtract Chemical Decontamination.  Innovative Technology Summary
Report, DOE/EM-0454. U.S.  Department of Energy, Office of Science and Technology (1998).
Available at http://apps.eTn.doe.gov/ost/pubs/itsrs/itsrl45Q.pdf. Accessed November 2004.

EET, 2004.  Environmental Extraction Technologies, Inc. Internet web site.
http://www.techxtract, com/about frame.html. Accessed November 2004.

EPA, 1998. The Super fund Innovative Technology Evaluation Program - Annual Report to
Congress - FY1997.  Report No. EPA/540/R-98/503.  U.S. Environmental Protection Agency,
Office of Research and Development. November 1998. Available at
http://www.epagov/ORD/SlTE/congress/congress.pdf. Accessed November 2004.

SAIC, 2003. Personal communications between W. Scott Fay of Active Environmental
Technologies and William D.  Ellis, PhD, of SAIC. July 2003.

Tyerech, 1998. Tyerech, Michael Richard Shelf stable hydrogen peroxide containing carpet
cleaning and treatment compositions. U. S. Patent No. 5,728,669. March 17,1998.

U.S. Navy, 1997. EET TechXtract Technology Evaluation - Pearl Harbor Naval Complex,
Oahu, Hawaii.  Internal report to the U.S. Navy, Pacific Division. April 1997.

                                         65

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66

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4.     FOAM AND GEL TECHNOLOGIES

4.1    Sandia Foam and Decon Green

4.1.1   Technology Description

Several peroxide-based systems are available for use in the decontamination of buildings,
structures, and equipment. Two specific technologies are discussed in this section: "Sandia
Foam" and "Decon Green."

A common ingredient to these technologies is hydrogen peroxide (H2O2).  Additional discussion
of liquid hydrogen peroxide in non-foam applications is presented in Section 3.4 of this report.
Most uses for hydrogen peroxide are based on its oxidizing properties and, as such, it becomes a
candidate to consider for decontaminating chemical/biological agents.

Sandia Foam
                                    r
Sandia Foam was developed by the Sandia National Laboratories and is manufactured by
EnviroFoam Technologies, Inc. (EFT) under the trade name EasyDECON®, and by Modec, Inc.
under the trade name Modec Decon Formula (MDF) 200®.  The Sandia Foam uses a combination
of surfactants and oxidizers to inactivate both biological and chemical agents.  These systems
have been shown to be effective against chemical agents, easily applied, and environmentally
friendly.  Both Sandia and the West Desert Test Center at Dugway Proving Ground have
reported 7-log (i.e., seven orders of magnitude) kills of Bacillus anthracis spores within one
hour.

The "foam" is somewhat of a misnomer as the chemical can be supplied or created as a foam,
liquid, or aerosol. How the foam kills spores—bacteria in a ragged, dormant state—still is not
well understood. It is thought the surfactants perforate the spore's protein armor and allow the
oxidizing agents to attack the genetic material inside.

Like a fire retardant, the foam could be sprayed from handheld canisters. When the foam is
deployed, it expands to about 100 times its liquid volume through a special nozzle that draws air
into the spray. The foam fills space and contacts chemical or biological agents in crevices and
on open surfaces. In several hours it collapses back to its compact liquid state.

Decon Green

Edgewood Chemical Biological Center (ECBC), Aberdeen Proving Ground, Maryland, patented
a similar peroxide-based system called Decon Green. This system has been demonstrated to be
effective against all chemical agents,  easily applied, and is considered to be environmentally
friendly (hence, the name "green").

This decontamination product is targeted to replace DS2 (Decontaminating Solution 2), the
Army's non-aqueous decontamination standard.
                                          67

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Decon Green is a simple solution of hydrogen peroxide, potassium carbonate, potassium
molybdate, propylene carbonate and Triton X-100® (a non-ionic surfactant) that affords the
rapid, broad-spectrum decontamination of chemical warfare agents, even at low temperatures
(-31 *C). The solution is non-corrosive to common surfaces of military interest and leaves no
toxic residues, so it is considered environmentally friendly. In use, carbonate and molybdate
catalytically activate the peroxide. Thus, the carbonate's basicity provides peroxy anion OOH-
to effect the selective perhydrolysis of nerve agents VX and GD to non-toxic products, and both
carbonate and molybdate generate peroxo species which afford oxidation of blister agent HD
(e.g., mustard gas), initially, to the nonvesicant sulfoxide.  Besides chemical agents, Decon
Green also  affords the destruction of anthrax spores to undetectable levels (as discussed below in
Section 4.1.4).  Decon Green and other common decontaminants were tested for efficacy of
chemical agent decontamination of painted surfaces of military interest (Wagner, et al., 2002).

4.1.2  Technical Maturity

Sandia Foam

Vendor data suggest that the Sandia foam systems may be effective against both chemical and
biological agents (see Section 4.1.4).  Full scale application to buildings contaminated with
anthrax was tried (see Section 4.1.3).  However, testing by EPA using the AOAC Sporicidal
Activity Test on one of Envirofoam Technology's Products indicated that ^ contrary to claims
on the product label - the formulation of this product tested at that time was not effective in
decontaminating 6 logs of B. subtillis spores on a hard, non-porous surface at one hour contact
time. As a result, the crisis exemption for EasyDECON and ModecDecon formula was
withdrawn  on March 29, 2002.

Decon Green

No detailed scale up information is available.  Decon Green has been successfully  sprayed using
a standard military decontaminating apparatus (M13) and decontaminant pumper (M21) (ECBC,
undated). It is not clear from the source materials if agent testing was conducted during this
testing.

4.1.3  Applications of the Technology

Applications of Hydrogen Peroxide

Hydrogen peroxide releases oxygen readily, and acts both as a general oxidizing agent and as a
convenient source of readily available active oxygen. Discussion regarding the'applications of
aqueous hydrogen peroxide is presented in Section 3.4 of this report.  Compared to chlorine (or
ozone, chlorine dioxide, or UV light), H2O2 is a rather poor disinfectant, and is not approved as a
stand-alone treatment for microbial control in water systems.
                                           68

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Applications ofSandia Foam

The Sandia Decon Formulation was on hand for use during high-profile events such as the 2000
Democratic National Convention in Los Angeles, California, the 3rd Presidential Debate in St.
Louis, Missouri (October 2000), and the 2002 Winter Olympics in Salt Lake City, Utah (Sandia,
2002).

Sandia Foam was used as one component in the decontamination of the Capitol Hill complex
following tiie anthrax-containing letter that was received in Senator Daschle's suite in the Hart
Senate Office Building (HSOB) in October 2001. In addition to the contamination in the
Daschle suite, surface environmental sampling showed anthrax contamination in several other
suites and common areas on several floors of the HSOB, as well as in filters within two heating,
ventilation, and air conditioning systems that served the Daschle suite.  Cross-contamination was
also discovered in several other buildings and  mail processing areas. The Daschle suite and the
two ventilation systems serving it were fumigated with chlorine dioxide gas. The other areas
within the HSOB where anthrax had been detected, and the other cross-contaminated buildings
in the Capitol Complex, were cleaned using various surface treatment methodologies. The
primary treatment of these other areas  utilized chlorine dioxide liquid or hypochlorite bleach.
Sandia Foam was used for some initial surface treatments, but was replaced by aqueous chlorine
dioxide and bleach, which were easier to clean up. High-efficiency particulate air filter
vacuuming was sometimes used as a preliminary source reduction  step prior to other surface
treatments.  Extensive post-remediation environmental sampling at the Capitol Hill site was all
negative for growth of anthrax spores, and on January 22, 2002, the Hart Building was cleared
for re-occupancy (Whitman, 2002).

       Although the overall decontamination of the HSOB was successful, the effectiveness of
the Sandia Foam during this process was not specifically evaluated.  There were no quantitative
measurements of pre- and post-treatment contamination levels in areas treated solely by Sandia
Foam.

Applications of Decon Green

Decon Green has not been applied outside of a test environment.

4.1.4   Evaluation of Available Data

Solutions of hydrogen peroxide, bicarbonate, and a suitable co-solvent for water-insoluble agents
serve as the basis (activated hydrogen  peroxide) for a broad decontamination application for G
agents, VX and HD. More extensive discussion concerning the performance of aqueous
hydrogen peroxide formulations in destroying chemical agents is presented in Section 3.4 of this
report. In particular, Section 3.4 includes data regarding mixtures  of hydrogen peroxide and one
or more components of Decon Green (i.e., peroxide activators such as bicarbonate and
molybdate), although no data on the aqueous version of Decon Green itself.
             ...alters Library
        ... vocie3404T
       •insylvania Avenue NW
      •jhwigfon, DC 20460
       202-566-0556
69

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Sandia Decon Formulations
Tests conducted at Sandia showed that the foam destroyed simulants of VX, HD, Soman (GD),
and anthrax (Modec, 2003a; Tucker et al., undated).

In October 2000, Sandia was funded by DOE to develop an enhanced version of their foam
(originally called DF-100) to optimize performance for military and civilian first responders
(Modec, 2003b).  This resulted in the new decon formulation, DF-200 [Sandia, undated].  Based
on test data, a 99.99999 percent kill of anthrax simulant was achieved  after 30 minutes. This
compares with a 99.99 percent kill for DF-100 for the same time period.  Modec, Inc. has been
licensed by Sandia to commercially produce DF-200. Modec sells this product as MDF-200.
Commercial production began in December 2001.

Sandia reported the results of the original and improved formulations.  Testing was conducted
using chemical and biological agent simulants. The results are shown in Table 4.1-1.

           Table  4.1-1. Summary  Reaction Rates of Agent Simulant Testing -
                               Versions of Sandia Foam
Formulation

DF-100 (pH 8)
DP-100(pH9.2)
DF-200

DF-100 (pH 10)
DP-100 (pH 9.2)
DF-200

DF-lOOACoHS)
DP-100A(pH9.2)
DF-200


DF-100A (pH 8)
DP-100A fpH 9.2) -
DF-200
1 minute
15 minutes
60 minutes
HD simulant (2-chloroethyl phenyl sulfide), % decontaminated
18
16 >
94
42
38
98
VX simulant (O-ethyl S-ethyl phenylphos
45
33
66
99
71
99
81
83
ND
phonothioate,
ND
93
ND
G Agent Simulant (diphenyl chlorophosphate)
53
ND
ND
ND
ND
ND
ND
ND
ND
Anthrax simulant (Bacillus globigii spores)
30 minutes, % kill
99.99
90
99.99999
60 minutes, % kill
99.99999
99.9
99.99999
Note: ND = below detection limit

Additional live agent testing was conducted at IIT Research Laboratories using test protocols
and DF-200 product supplied by Sandia National Laboratories. The results are shown in Table
4.1-2.

 Table 4.1-2. Live Agent Kill Rate Summary (testing conducted at IIT Research Institute)
Agent
GD
+/- 0.01VX
HD
AmesRIID*
ANR-1*
1 minute, % kill
99.98 +/- 0.01
91.20+/-8.56
78.1 3 +/- 10.53
Not measured
Nor measured
IS minutes, % kill
99.97 +/- 0.01
99.80 +/- 0.08
98.46 +/- 1.43
99.99999
99.99999
60 minutes, % kill
99.98 +/- 0.01
99.88 +/- 0.04
99.84 +/- 0.32
99.99999
99.99999
*Strain of B. anthracis
                                         70

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The Modec Decon Formulation (MDF-200) - a similar product also is marketed as EasyDECON
200 by Environfoam Technologies - is actually a three-part system. Part A, a biodegradable
mixture of a cationic surfactant and a fatty alcohol, is formulated from benzyl C12-18 alkyl
dimethyl quaternary ammonium compounds (the surfactant), isopropyl alcohol, and
N,N,N,N',N'-pentametiiyl-N' tallow-l,3-propan-diammonium dichloride. Part B is stabilized
hydrogen peroxide (8%), and part C is glycol diacetate.  The foam is composed of 90.7 percent
water, 3.99 percent part B, 1.8 percent part C and the remainder part A.

The Sandia Decon Formulation was field tested at the U.S. Army Proving Grounds at Dugway,
Utah (Sandia, 2003). The field test was designed to test the effectiveness of one formulation in
killing anthrax spores.  The anthrax simulant, Bacillus globigii was sprayed onto various panels
(2' x 2') of materials which would commonly be found in a typical office building. Since the
area to be decontaminated was relatively small, and to show versatility, the formulation was
deployed onto the panels as an aqueous spray (using a standard paint sprayer) rather than as a
foam. After 20 hours exposure to the formulation, Dugway personnel tested the panels for
surviving spores. The tests were repeated on four consecutive days, and the results for the
Sandia Decon Formulation indicated the spores were eliminated (see Table 4.1-3). The 20 hour
exposure exceeds the one hour contact time identified on the label direction and used by EPA in
assessing the effectiveness of the product for crisis exemption purposes.

    Table 4.1-3. B. globigii (Anthrax Simulant) Spore Kill During Dugway Filed Tests
Surface
Floor (painted concrete)
Floor (tile)
Floor (carpet)
Floor (wood)
Window (glass)
Painted wall below window
Left hand wall panels
Wall (stucco)
Painted wall above carpet
Carpeted wall
Door
Ceiling
Contaminated
^Surface average in CFU*/in.1)
7.67x10'
1.31 xlO7
1.23 xlO7
7.30 x 10*
5.32 x 10"
8.16xl04
4.70x10"
2.80 x 10s
4.56 x 104
1.08 xlO6
3.13x10"
8.49 XlO2
Decontaminated
(ND = not detected)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
*CFU = colony-forming units

The MDF-200 has also been demonstrated to be effective against chemical agents. Testing was
conducted at ECBC, Aberdeen Proving Ground, MD. The decontamination effectiveness is
compared to DS2 (the Army's non-aqueous decontamination standard). Sandia reports that after
1 hour of contact, 100 percent of the chemical agent was decontaminated (see Table 4.1-4).

           Table 4.1-4. Percent Decontamination in Live Agent Testes at ECBC

Decontaminant
DS2
Sandia Foam (MDF 200)
HD
lOmin
100
47
1 hour
100
100
CD
lOmin
100
>99
1 hour
100
100
vx
lOmin
100
100
1 hour
100
100
                                          71

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Sandia has also reported results using the Modec foam against selected Toxic Industrial
Chemicals (TICs).  Results are reported in percent decontamination of the TIC (see Table 4.1-5).

           Table 4.1-5. Modec Decon Foam against Toxic Industrial Chemicals
TIC
Malathion (liquid)
Hydrogen Cyanide (gas)
Sodium Cyanide (solid)
Butyl Isocyanate (liquid)
Carbon Disulfide (liquid)
Phosgene (gas)
Anhydrous Ammonia (gas)
% Decontamination
1 minute
89
>99
93
99
>99
98 -
>99
15 minutes
95
>99
'98
BDL
>99
>99
>99
60 minutes
BDL
>99
>99
BDL
BDL
>99
>99
Note: BDL = below detection limit

The above results of testing with the Sandia Foam formulation - representing information made
available primarily from Sandia National Laboratory, Modec, Inc., and EnviroFoam
Technologies, Inc. web sites - appear to indicate that the decontamination formulation is
effective against chemical and biological agents.  It must be noted that no analytical method
detection limits, analytical method description, quality control data, nor test conditions were
available to validate the results as presented. Therefore, no critical review of the results as
presented is possible.

EPA's testing of Sandia Foam products-using the AOAC protocol appears to disagree with the
above results. EPA's tests were conducted on EasyDECON 4215 (Envirofoam) using Bacillus
subtilis as the test organism.  Two media were tested: (1) a porcelain carrier innoculated with 9.2
x 10s spores;  and (2) suture loops innoculated with 2.0 x 106 spores.  The carriers were exposed
to EasyDECON 4215 for 60 minutes. The results are shown in Figure 4.1.1.
                                                                                    «i
Since Sandia Foam has an aqueous base, paper products will wrinkle after the solution is applied
and allowed to dry. EasyDECON 200 solution has been tested on a variety of surfaces.
Concrete, asphalt, wood, ceramic, carpet, fabric, leather, steel and aluminum are just a few of the
many surfaces tested.  Bare, steel objects are susceptible to surface rust after application.
                                           72

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4.1.5   Concerns for the User

Typical precautions for hydrogen peroxide should be observed. Material Safely Data Sheets
(MSDSs) for hydrogen peroxide and MDF-200 are available on the web.

SandiaFoam

Sandia claims that the foam represents no hazard, and the foam's MSDS indicates no reported
significant toxic effects. Respiratory protection may be required if workplace exposure limits
are exceeded. The manufacturer claims that the foam reduces environmental hazards to the point
where the effluent may be disposed of "down the drain." The foam is non-flammable and
advertised as a dual-use fire-fighting foam and CB decontaminant.  [For reference, it is noted
that the commercially available high-expansion Aqueous Film-Forming Foam (AFFF)—a fire-
fighting foam—must be stored and treated as hazardous material.]

Decon Green

This decontaminant is targeted to replace DS2.  The current design requires three separate
containers to be mixed prior to use. The Decon Green solution is reported to be non-corrosive to
common surfaces.

4.1.6   Availability of the Technology for Commercial Applications

Sandia Foam

The Sandia Decon formulations can be purchased from the following vendors:

       Modec, Inc.
       4725 Oakland St
       Denver, CO 80239
       Toll-free: (800) 967-7887
       Phone: (303) 373-2696
       Fax: (303) 373-2699
       Web: http://www.deconso 1 utions. com

       Envirofoam Technologies, Inc.
       2903 Wall TrianaHwy
       Huntsville, AL 35824
       Toll-free: (800) 542-4665
       Phone:(256)319-0137
       Fax:(256)461-8136                                      '
       Web: http://www. envirofoam. com

The Modec Decon formula MDF-200 is  available in a variety of configurations, as summarized
below:
                                         75

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      •      'Twin-Pak": boxed set of 5 gallons
      •      "Quik-Set": 10 gallon single container
      •      Single 55 gallon barrel
      •      Two-55 gallon barrels
      •      Two-250 gallon Intermediate Bulk Container or tote (IBC)
             Two-350 gallon IBC.

EasyDECON 200 decontamination solution is packaged in several convenient ready to mix
containers. Each container comes ready to use consisting of pre-measured components.
According to the manufacturer, preparing EasyDECON 200 decontamination solution is fast and
easy and is ready for use within minutes. EasyDECON 200 decontamination solution is
available in various sizes and amounts and is capable of remediating both chemical and
biological contamination.

EasyDECON 200 solution is sold in a variety of sizes and packages.  EasyDECON 200 solution
can be purchased in 2.5 gallon containers up to a 250 gallon tote.

EnviroFoam Technologies offers a variety of EasyDECON application equipment including:.
      •      Fogging systems
             - Apply decontamination solution to small enclosed areas
             - Adjustable droplet mist
      •      Handheld pump sprayers
             - Apply as a liquid rather than a foam
             - Small area decontamination
      •      MACAW® Backpack compressed Air Foam System
             - Manufactured by Intelagard
             - Portable self contained compressed air foam system
             - 5 gallon capacity
             - 35 foot stand-off distance
      •      Merlin® Handcart Compressed Air Foam (CAF) System
             - Manufactured by Intelagard
             - Handcart mounted CAF system
             -15 gallon capacity
             EASYCAFS® Foam Delivery Vehicle (FDV)
             - Compressed air foam system
             - Mounted on a 6x6 Polaris Ranger® all terrain vehicle
             - 75 gallon capacity
      •      Vehicle Mounted EASYCAFS Model 25 Low Profile Slip-in System
             - Self contained for truck transportability
             - Powered by 19HP air-cooled diesel
                                         76

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Decon Green

Developmental stages are complete and ECBC anticipates that Decon Green will be
commercially available in the near future and available to the military soon after that.

4.1.7   Advantages and Disadvantages

No specific information was found on how the Sandia foam systems were field tested.  It is
apparent that the foams can be used in small areas, single rooms, on office fixtures and
equipment. The technologies do not appear to be applicable to HVAC systems.

Sandia Foam

The Sandia Foam decontamination technologies are claimed to have to following advantages:

              Claimed to decontaminate chemical agents
       •      Claimed to be a general disinfectant for vegetative bacteria and viruses, although
              EPA's AOAC data raise questions regarding its efficacy
       •      Leaves no persistent toxic residues or toxic by products
       •      Non-corrosive
       •      Easy application (no special equipment required)
       •      Apply as foam, liquid spray or  fog
       •      Relatively rapid reactions - works quickly
       •      Applicable to various surfaces  (though may be a problem for some, such as paper)
       •      Stable over a wide temperature range including freezing temperatures and hot
              surfaces
              Variable shelf life claimed for various formulations; 10-year shelf life claimed for
              EasyDECON.

Issues associated with the use of the Sandia Foam decontamination technologies include the
following:

       •      Efficacy has not been independently verified
       •      Detailed analytical data need to be reviewed (non-detect value not related to
              method detection limits); analytical methodology not available for review
       •      No detailed scale up information available
       •      Public safety issues need to be  assessed when applied in the field
       •      Full scale demonstration: efficacy of application to equipment and structures is
              uncertain
       •      Bare, steel objects are susceptible to surface rust after application; paper will
              wrinkle
       •      Potential removal challenges following treatments in civilian settings
                                           77

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Decon Green

The Decon Green decontamination technology is claimed to have to following advantages:

             Leaves no persistent toxic residues
       •      Non-corrosive
       •      Easy preparation, no water required
       •      Easy application (no special equipment required)
             Rapid reactions
       •      Compatible with cold weather
       •      Stable over a wide temperature range including freezing temperatures and hot
             surfaces.

Issues associated with the use of the Decon Green decontamination technologies include the
following:

       •      Efficacy has not been independently verified '
       •      Detailed analytical data need to be reviewed
       •      No detailed scale up information available (used successfully with M13
             decontaminating apparatus and M21 decontaminant pumper).
       •      Designed for military applications; practicality for building applications needs
             further demonstration.
       •      Public safety issues need to be assessed when applied in the field

4.1.8  Potential Areas for Future Research

Data generated under laboratory controlled conditions show that the Sandia Foam and Decon
Green are effective to some degree in decontaminating chemical and biological agents, but
substantiating data have not been reviewed by EPA. The solutions, therefore, are promising
candidates for additional test and development. Under some conditions, field trials were
conducted with good results.

It is not clear how well the decontamination solution will withstand excessive temperatures and
"dirty" surfaces such as asphalt and concrete. The stability of hydrogen peroxide is understood
from the literature, but actual field test data were not available for evaluation. It is suggested
that a test program be designed to better evaluate the "real world" parameters and effectiveness
of these decontamination systems.

4.1.9  References for Section 4.1

ECBC, undated.  Decon Green Fact Sheet.  Edgewood Chemical Biological Center.

Modec, 2003a. Modec Decon Foam - Results Against Selected Toxic Industrial Chemicals.
Modec, Inc. hftp://www. deconsolutions, com/TIMS.htm. Accessed November 2004.
                                           78

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Modec, 2003b. Performance of the Modec Decon Formulation (MDF-200). Modec, Inc.
htto:,'7wwvv.deconsolutions.com/FormuIation_accelerated.htTn. Accessed November 2004.

Sandia, undated. DF-200 -An Enhanced Formulation for Decontamination and Mitigation of
CBWAgents and Biological Pathogens,  Undated draft report.

Sandia, 2002. Sandia Decon Formulation for Mitigation and Decontamination of Chemical and
Biological Warfare Agents. Publication No. SAND2000-0625. Sandia National Laboratory.
http://wv\?\v.satidia.gov/SaiidiaDecon//factshests/overview apr2002.pdf. Accessed November
2004.

Sandia, 2003. Field Demonstration for Biological Agent Decon (web site).
http://www.sandia.gov/San diaDecoTL/demos/detno5.h.tm. Accessed November 2004.

Tucker et al., undated. Tucker, M.D.; Williams, C.V.; Tadros, M.E.; Baca, P.M.; Betty, R.; and
Paul, J. Aqueous Foam for the Decontamination and Mitigation of Chemical and Biological
Warfare Agents, Sandia National Laboratories, Albuquerque Staff Augmentation Providers, and
Orion International Technologies.

Wagner et al., 2002.  Wagner, G.W.; Procell, L.R.; Henderson, V.D.; Sorrick, D.C.; and Yang,
Y.-C. "Decon Green". Presented at the 23rd Army Science Conference, Orlando, Florida. 2002.

Wagner and Yang, 2002. Wagner, G. W.; and Yang, Y.-C. "Rapid Nucleophilic/Oxidative
Decontamination of Chemical Warfare Agents," Industrial Engineering and Chemistry
Research, 41 (8): 1925-1928 (2002).

Whitman, Christine Todd.  Statement before the Committee on Environment and Public Works,
September 24,2002. U.S.  Environmental Protection Agency.
                                         79

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4.2    Canadian Aqueous System for Chemical-Biological Agent Decontamination
       (CASCAD®)

The Canadian Aqueous System for Chemical-Biological Agent Decontamination (CASCAD)
was developed in the late 1980s as a classified program under Defence Research and
Establishment Suffield (ORES). In the 1990s the concept was shared outside of ihe defense
community.  The system was originally designed for the decontamination of military equipment
exposed to chemical or biological warfare agents. The formulation was designed to have
minimal effect on materials while inactivating biological and chemical agents. Additional
considerations were to minimize toxicity, maintain compatibility with existing chemical and
biological agent detectors, and to make the formulation a stable foam to enable coatings of
contaminated surfaces for extended periods of time.  CASCAD is one of the original eight
decontaminants identified by a study under the Joint Fixed Site Decontamination program by the
U.S. Government.

4.2.1   Technology Description

CASCAD contains several surfactants in a proprietary mixture in combination with chlorinating
agents. It is  a well-published decontamination system that contains Fichlor (sodium
dichlorisocyanurate) as an active ingredient. The mixtures are supplied as a powder and liquid,
packaged separately.  The powder is the time-release chlorinating agent that is responsible for
most of the effectiveness of the material. When combined, a foam is generated that is sprayed
on the equipment to be decontaminated. The rigidity of the foam allows for a longer contact
time than pure liquids resulting in improved inactivation of biological and chemical agents.

The system is extremely scalable, is available in a 20-liter backpack module, and can also be
connected to a fire hose for coverage up to 2,500 square meters per hour. The backpack version
is self-contained and uses air pressure to create the CASCAD foam. In larger applications, water
is added to create the foam.  Figure 4.2-1 shows large scale application of the foam.

A unique feature of this technology is the ability to use water from a variety of sources. The
foam is equally active using  distilled water, tap water, non-potable water, and even seawater.
This degree of versatility minimizes the logistical burden of system implementation. This factor
is also attractive for building remediation because the water  supply for the building can be used
for the generation of the foam. Clean up is conducted using  a wet-dry vacuum system.
The patented chemical formulations used by NBC Team Ltd. are designed for both blast
mitigation as well as the decontamination of chemical, biological, and radiological compounds.
The different applications require different formulations. The blast mitigation foam is a much
more dense foam while the radiological formulation is designed to wash off particles and is
much less dense. The formulation for decontamination of chemical and biological agents is
more dense than the radiological^ but less dense than the blast mitigation foam.  In addition to
the alterations in foam densities, the amount and formulation of the active ingredients are also
tailored to specific applications.
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          Figure 4.2-1. Demonstration of the Foam Application on a Tank Vehicle

4.2.2  Technical Maturity

The CASCAD system is completely mature and ready for operations. The Canadian Defence
Research Establishment originally funded the technology and have transferred the technology for
commercialization. The commercialization team consists of the Defence Research
Establishment Suffield (ORES), The Royal Canadian Mounted Police (RCMP), the National
Research Council (NRC), the U.S. Department of Defense (DoD), George Cowan Enterprises,
O'Dell Engineering Ltd., and NBC Team Ltd.  O'Dell Engineering Ltd.  was founded in 1995 to
develop and market unique Chemical and Biological weapon decontamination products
worldwide.  NBC Team Ltd. is the authorized  distributor of products. Their address is:

P.O. Box 11040
921 Barton St.
Stoney Creek Ontario, Canada L8E 5P9
Telephone: 905-643-8801
Fax: 905-643-8824
Email: info@nbcteam.com
Web site: www.nbcteam.com
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4.2.3  Applications of the Technology
Fichlor is a chemical that is effective in decontaminating chemical and biological agents.
Chloroisocyanurates are used as disinfectants in general sanitizers, scouring powders, household
bleaches, institutional and industrial cleaners, and swimming pool/ hot tub disinfectants (Kirk
Othmer, 1993). Chloroisocyanurates (sold in granular or tablet forms) are among the leading
swimming pool sanitizing agents in the U.S., with 1992 use of approximately 50,000 tons (Kirk
Othmer, 1998).

4.2.4  Evaluation of Available Data

Chemical agent decontamination

Comparative information regarding the effectiveness of the CASCAD system versus well known
decontamination formulations is shown in Table 4.2-1 (published by NBC Team Ltd.).
Decontaminating Solution 2 (DS2) is 70 percent diethylenetriamine, 28 percent 2-
methoxyethanol, and two percent sodium hydroxide (NaOH).  C8, also called the German
emulsion, is 15 percent tetrachloroethylene, 76 percent water, one percent anionic surfactant, and
eight percent calcium hypochlorite, Ca(OCl)2 (National Institute of Justice, 2001). No analytical
data were available for a technical assessment of the decontamination effectiveness.

                   Table 4.2-1. Comparison of CASCAD to DS2 and C8
Feature
Form as applied
Form as delivered
Additional ingredients
Destroys agents on surface
Nerve -G,V
Vesicants - H, L
Biological Agents
Destroys C W agents in paint
Toxicity of residue
Effect on typical:
Paint
Rubber
Aluminum
Tested for removal and
control of radioactive
contamination
Typical Application Method
DS2
Clear liquid
Clear liquid in quart
containers
None
Yes
Yes
Yes
Not suitable
Highly toxic
Removes
Softens/breakdown
Pitting
Not tested
20 litre spray
C8
Cloudy liquid
Multi-part liquid &
powder requiring
emulsifying
Water
Yes
Yes
Yes
Not suitable
Highly toxic
Removes some
Softens
Minor
Not tested
500 gal mixer
requires approx. 30
minutes
CASCAD
White Foam
Powder and liquid
Water (fresh, salt, grey)
Yes
Yes
Yes
Yes
Non-toxic
None
None
None
Best tested
Continuous injection system
reloadable without shutdown.
Draw from any available
water source
 a. Based on Canadian Forces testing and publications. C W agents which contain arsenic will retain less toxic
arsenic compounds in the residual material.
 b. Liquid nature of DS2 and C8 makes it difficult to remain in contact with surfaces and effectively remove agent
without destroying surface finishes.
 c. Canadian Forces and French Government test results.
Source: NBC Team Ltd. (Vanguard Response Systems, Inc.) http://www.nbcteam.com/products decon index.shtml
                                           82

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Table 4.2-2, published by NBC Team Ltd. (now Vanguard Response Systems, Inc.), reports the
effectiveness of CASCAD against standard chemical warfare agents. The amount of chemical
agent used at the start of the experiment is not reported. This makes the evaluation of the data
very difficult

         Table 4.2-2. CASCAD Effectiveness Against Chemical Warfare Agents
Agent
Nerve Agent GA

Nerve Agent 
-------
Insecticide, Fungicide, and Rodenticide Act (FIFRA) sterility requirement, it does meet the
North Atlantic Treaty Organization (NATO) decontamination requirement.

In a separate publication from ORES, the effect of CASCAD on Bacillus globigii spores was
evaluated. The authors concluded that CASCAD was a very effective decontaminant (Spence,
undated). While the conclusion appears to be supported by the data, the data are qualitative and
not quantitative. Therefore one can not calculate a log reduction factor from these results.
       *
Table 4.2-3 presents product information published by the commercial vendor of CASCAD
indicating effectiveness against biological material. No tests have been reported against any
toxins or toxic industrial compounds.

                   Table 4.2-3. Effectiveness of CASCAD Treatment
Agent f
Bacillus globigii spores
ir
Erwinia
Bacillus anthracis spores
ii
Time of exposure (minutes)
5
60
5
30
30
Percentage of agent remaining
viable
0.0001%
0.000001%
0.000001%
0.001%
0.011%
Source: Vanguard Response Systems, Inc.

Evaluation of "Rapid Lightning Report"

Rapid Lightning was a biological warfare simulant sampling and decontamination exercise
funded by the Defense Threat Reduction Agency in August of 1999.  CASCAD killing
efficiency was evaluated for the BW simulants Bacillus globigii (Bg) spores, and Erwinia
herbicola (Eh) vegetative bacteria. This exercise represented the first evaluation of CASCAD in
the U.S.  These laboratory trials were a series of experiments that varied the mix of CASCAD to
simulant in ratios from 10:1 to 0.5:1, with contact times ranging from five to 60 minutes. No
comparisons were conducted against any other decontamination technology with the exception
of 5 percent bleach. CASCAD effectiveness was determined by measuring the number of
colony forming units (cfu) in the presence and absence of CASCAD. A six log reduction was
considered effective decontamination.

The data presented support the use and further evaluation of CASCAD as a decontamination
protocol for spore remediation. The data presented in the Rapid Lightning report do not provide
standard error measurements.  This degree of resolution is essential because of the apparent
variability of the protocol. In the Rapid Lightning study, CASCAD at a 1:1 ratio for a 60 minute
exposure demonstrates an eight log reduction of Bg spores, while the same experimental
conditions yielded only a 2.5 log reduction.  The authors proposed this variability was due to
different spore preparations. However, it is unlikely that spore preparation could adequately
explain such a divergence in results.  Accordingly, additional experimentation is required to
determine the actual effectiveness against a spore population.

Experiments with the vegetative bacteria, Erwinia herbicola, demonstrated a seven log reduction
at a 1:1 volume ratio even after only five minutes contact time. These data are consistent with
                                          84

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the accepted fact that vegetative bacteria are much more susceptible to destruction than the
bacterial spore.

4.2.5   Concerns for the User

According to results published by the Canadian Government, the residue from CASCAD is
non-toxic. Unlike some of the harsher decontaminants like DS2, CASCAD is reported not to
harm paint, rubber, or aluminum surfaces. While the material in the formulation of the foam
does not appear to be toxic to users, one must recognize that the target of the remediation is
harmful to the user.  Therefore, the user should employ personal protective equipment while
using this product  A user should consult the MSDS for the active ingredient in CASCAD,
MILCON-T.

4.2.6   Costs

CASCAD products are available commercially. The fully integrated system that can be hooked
up to a fire truck or other water source retails for $85,000. Intermediate sized systems are also
available.  A portable backpack sprayer is $2,500. Coverage areas as a function of deployment
system are not mentioned. However decontamination for 10 square feet of surface requires one
liter of CASCAD. Operational costs range from $0.30 to $0.60 per square foot depending on
quantity ordered. These operational costs are for outside equipment decontamination.  Use
within a building could have significantly greater operational costs, based on recent experience
in decontaminating some buildings impacted by the 2001 anthrax mail incident.

4.2.7   Advantages and Disadvantages

CASCAD is a demonstrated technology for remediation of chemical and biological warfare
agents. The product was designed for the military for use in battlefield environments.
Demonstrations have been on the exteriors of tanks, ships, and aircraft. In these situations the
product performs as stated. This product was not developed as a building interior remediation
alternative.

With the recent terrorist attacks with Bacillus anthracis spores in envelopes, the CASCAD
vendor has claimed value for this product in such applications. The value claimed is two-fold.
The first is in limiting the spread of the biological or chemical agent.  The foam acts as an
insulator to prevent further dissemination. The second effect is the decontamination. While this
may be a useful approach for rapid isolation, it is much more invasive and destructive than
fumigation due to the wet nature of the product and the need to remove after application. These
are vendor claims that have not been evaluated by the EPA.

CASCAD, as well as other foam based decontamination alternatives, is very labor intensive
when applied to building interiors.  Sandia Foam was used for remediation of the Dirksen and
Ford Office Building mailrooms  in the fall of 2001; a material expected to have a consistency
similar to CASCAD. Not only was the foam not fully effective, the clean up operations were
extensive and time consuming  (personal communication with the Coast Guard personnel
conducting remediation operations).

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The most significant advantage to a system of this type is immediate isolation and containment
of (he exposed area. Application of this type of technology could have significant impact on
spread of the contamination.

4.2.8  Potential Areas for Future Research

The CASCAD formulation is mature for chemical and biological decontamination operations.
Additional documentation by independent researchers would validate the vendor's claims. The
concept for utilization of this type of a product for initial isolation is quite promising, but not
validated by experimentation. The data presented in this report are very suggestive of efficacy,
but more rigorous experimental conditions are required.

4.2.9  References for Section 4.2

Kirk-Othmer, 1998. Encyclopedia of Chemical Technology, Fourth Edition, Volume 25, "Water
(Treatment of Swimming Pools, Spas, and Hot Tubs)."

Kirk-Othmer, 1993. Encyclopedia of Chemical Technology, Fourth Edition, Volume 7,
"Cyanuric and Isocyanuric Acids."

Kourmikakis et al., 2000.  Kourmikakis, B; Purdon, J.G; and Chenier, C.L. Verification of
CASCAD in the Decontamination of Bacillus anthracis Spores. Report ECR-2000-141.  Defense
Research Establishment, Suffield. 2000.

National Institute of Justice, 2001. Guide for the Selection of Chemical and Biological
Decontamination Equipment for Emergency First Responders: Volume I.  NIJ Guide 103-00,
Volume I, U.S. Department of Justice.  October 2001.

Spence, undated. Spence, M; Ho, J.; and Ogston, J. Decontamination of Vehicle Using
CASCAD After Exposure to Biological Aerosol Hazards.
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4.3    L-Gel

L-Gel is a spray-on decontamination gel that has been found effective to some degree against
both toxic chemicals and biological agents.  The following sections describe how it works,
laboratory and field test results, and practical considerations for its use.

4.3.1   Description of the Technology Alternative

L-Gel is a decontamination technology developed at Lawrence Livermore National Laboratory
(LLNL) with three important characteristics:

       •      It oxidizes chemical warfare agents (CWAs)
       •      It kills bacterial spores used as biological warfare agents (BWAs)
       •      It sticks to vertical and overhead surfaces.

Raber and McGuire, of the Environment Protection Department at LLNL, have reported on the
development and testing of L-Gel (Raber and McGuire, 2002; LLNL, 2002; Raber and McGuire,
undated). It is non-toxic, non-corrosive, easy to manufacture (and therefore relatively
inexpensive), and easy to deploy (LLNL, 2002). The oxidizing agent in L-Gel is Oxone®, a
Dupont Corporation patented triple salt with the following formula (DuPont 1998a):

       2KHS(VKHSCVK2SO4

The active ingredient in Oxone is the first component of the triple salt, and is called potassium
peroxymonosulfate. The peroxymonosulfate anion is a moderate strength oxidizer, strong
enough to oxidize a halide anion to a halogen (neutral) or a hypohalite anion, a ferrous cation to
ferric, and a manganous cation to manganic  (DuPont 1998a).

Oxone has been shown in laboratory studies to oxidize VX to ethyl methylphosphonic acid
(BMPA) and diisopropyl taurine (Yang, Baker,  and Ward, 1992):
MeP(=0)(OEt)SCH2CH2N(iPr)2
             VX
                                       3KHSO5
                                       Potassium
                                       Peroxymonosulfate
       MeP(=O)(OEt)OH
       Ethyl Methyl-
       phosphonic Acid
                          H03SCH2CH2N(iPr)2
                          Diisopropyl
                          Taurine
H2O -»
Water
3KHSO4
Potassium
Bisulfate
where Me = methyl, Et = ethyl, iPr = isopropyl.
The sulfur in the thiol ester link in VX is oxidized to a sulfonic acid functional group, producing
the two products from VX that are much less toxic than VX. Potassium bisulfate is a neutral salt
with very low toxicity.
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The gelling agent in L-Gel is Cab-0-Sil® EH-5, a synthetic amorphous colloidal silica (silicon
dioxide) made by Cabot Corporation (LLNL, 2002). Cab-0-Sil EH-5 has an average particle
length of just 0.2-0.3 urn (Cabot, 2002). When Cab-O-Sil EH-5 is added (15 percent) to an
aqueous solution of Oxone, a gel is formed that can be applied to surfaces using paint spraying
equipment After application, it begins to dry and thicken, so that it adheres well to walls and
ceilings.                 |T                                                           •

L-Gel is packaged as a high-viscosity, gelatin-like semi-solid, as shown in Figure 4.3-1, that is
liquified by shaking or stirring.  The liquified product can be applied using paint spraying
equipment that is commercially available (Raber, 2002). The researchers note that due to L-
              Figure 4.3-1.  L-Gel, Delivered as Semisolid, is Liquified for
              Use
              Source: LLNL, 2002.

Gel's acidic properties, stainless steel spray nozzles must be used (Raber and Maguire, 2002).
Decontamination with L-Gel takes about 30 minutes after application.  L-Gel eventually dries
out completely, in about one to six hours, to a residue that can be removed by vacuuming.

43.2  Technical Maturity

L-Gel has been tested for decontamination of BWAs and CWAs, in the laboratory and in the
field (see Section 4.3.4). It is not yet commercially available. It has been developed in three
different forms:
       •      L-Gel 115 was the first decontamination gel developed by LLNL
       •      L-Gel 200, an improved version of L-Gel 115, is being developed to have the
              ability to penetrate coatings of paint or varnish
       •      An aerosol version of L-Gel is being developed for decontamination of the
              interior of ventilation systems.

LLNL is negotiating with several companies to license the manufacturing and marketing of L-
Gel.

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commonly used by the US military. The CWAs were placed on the substrates for 15 min, then
L-Gel was applied and allowed to dry for 24 hr. Samples were collected, extracted with 10 rnL
of dichloromethane, and the extracts were analyzed.  Agent decontamination was complete in all
but the GD tests on acrylic- and polyurethane-coated surfaces.  All VX and HD was treated, with
detection limits of 0.1 ng/mL for VX and GD, and 1.0 (ag/mL for HD.  (If it is assumed that the
extracts were concentrated to 1 mL before analysis, the treatment effectiveness for "complete"
decontamination can be calculated by the reader to be at least 96 percent for VX and GD, and 69
percent for HD.)

At Porton Down in the UK, L-Gel was laboratory tested for its  decontamination effectiveness on
thickened GD (TGD) and thickened HD (THD) applied to about 3 by 5 inch metal plates painted
with either alkyd or polyurethane paint. The thickened CWAs were applied to the test surfaces 1
hr before decontamination. L-Gel 115 was then applied to the metal plates in a vertical position
with a commercial compressed air paint sprayer. After 30 min, the sample plates were sprayed
with ambient temperature high pressure water, then soaked in isopropanol for 2 hr, and the
extracts were analyzed. (One would assume that the untreated control plates were also sprayed
with high pressure water, and that the analyses represented only the agent remaining that had
diffused into the paint.) L-Gel 115 decontaminated 35 percent  of the TGD and 50 percent of the
THD in the alkyd paint, and 64 and 66 percent in the polyurethane paint, respectively.

To be effective, a technology must not only  clean the contaminated surface but also reach below
the polymeric paint to treat CWA that penetrated the surface  during the attack or as a result of
surface cleaning.  The Porton Down test required L-Gel to demonstrate effective treatment of the
thickened agents on the surface as well as treatment of contaminants below the surface of the
polymeric paints within 30 minutes. The 30-minute period allowed in the Porton Down test is
not adequate time and seems to be an impractical test. Complete removal of the paint layer
would seem to be more appropriate if rapid decontamination  is  important. Alternatively,
multiple applications of L-Gel, with gentle heating of the paint  layer to enhance diffusion, might
be considered. (See section 3.2, in which TechXtractis applied many times for difficult
decontaminations.) This is the only test conducted with L-Gel that specifically required
subsurface decontamination. The solution suggested by the developers of L-Gel, for further '
development, was incorporation of a co-solvent. They said that this might "eliminate the
problem with gelled chemical agents."  The problem may also exist on any painted horizontal
surface, with any agent persistent for at least 1 hour.  Interestingly, the Porton Down study data
did not include results for any  other decontamination method for comparison.

L-Gel Laboratory Tests with BWAs

L-Gel 115 was also tested at LLNL against BWA surrogates  on varnished wood, painted steel,
glass, fiberglass, and carpet, as with CWA surrogate tests (Raber and McGuire, 2002; LLNL,
2002). The L-Gel was applied to each agent-contaminated test surface, allowed to dry for 30
min to several hours, and then surrogate residual levels were  determined.  L-Gel 115 was found
to be more than 99 percent effective for all agents on all surfaces.
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LLNL also performed in vitro tests of two safe (nonvirulent) strains of the biological warfare
agents (BWAs) Bacillus anthracis (spore form) and Yersinia pestis (bacteria): Sterne and Strain
D27, respectively.  The agar plate resistance test is a standard test for measuring the efficacy of
antibiotics. L-Gel was more than 99.9 percent effective in killing the spores and bacteria
(LLNL, 2002).

L-Gel Field Tests with CWAs

L-Gel was field tested by the Military Institute of Protection in Bmo, Czech Republic against
real CWAs during October, 1998. L-Gel 115 was tested outdoors on aged (more than 20 years
old) concrete, new concrete, aged asphalt, and new asphalt. The performance of L-Gel was
compared with a standard water solution of high test hypochlorite (HTH), for treatment of GD
and VX (the latter on new substrates only).  Agent was deposited on a circular area of about 20
m2 using a hand sprayer, at a density of about 15 g/m2.  After 2 hr, untreated agent samples were
collected. The decontaminant was then sprayed on about 5 m2, allowed to remain in contact for
30 min, then 25 cm2 samples were collected and analyzed.  L-Gel showed 98,98, and 70 percent
agent destruction for GD on new and old asphalt and for VX on new asphalt, respectively; HTH
showed 80,95,  and 72 percent destruction for the same agent-substrate combinations.  L-Gel
showed 100,98, and 99 percent agent destruction for GD on new and old concrete and for VX
on new concrete, respectively; HTH showed 100,95, and 95 percent destruction for the same
agent-substrate  combinations. In summary, L-Gel was slightly more effective than the standard
HTH decontamination solution in four tests; equal in one test; and slightly less effective in one
test.

L-Gel Field Tests with BWAs

In December, 1999, L-Gel was field tested on surrogate bacterial spores at the U.S. Army
Soldier Biological and Chemical Command (SBCCOM) facility at Dugway Proving Ground in
Utah. Initial surrogate organism counts  on 40 cm2 panels of acoustic ceiling tile, tightly woven
fabric, fabric-covered office partition, painted wallboard, concrete slab, and painted metal were
about 107 spores/10 cm2. L-Gel was applied, and allowed to stand for 24 hours. Swabs samples
of the panels were collected, and live spore counts were reduced by an average of 99.988
percent, and a minimum of about 99.96 percent (LLNL, 2002) (See Table 4.3-1).

Table 4.3-1.  Surrogate Spore Counts Before and After L-Gel Treatment*
Test Panel Material
Cement
Ceiling
Panel fabric
Painted metal
Painted wallboard
Carpet
Spore Count Before
2xl06
1.5x10' „
4xl06 \
4x10'
6 x 106
3x10"
Spore Count After
5xl02
6xl02
5xl02
IxlO2
4xl02
IxlO2
Reduction
99.98 %
99.96 %
99.99 %
99.998 %
99.993 %
99.997 %
* Level of detection was 1 x 102 spores. Counts were averages of five trials, for areas of 10 cm2. Before and After
counts were estimated for this table from a logarithmic-scaled graph of results (LLNL, 2002).
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In October, 2000, LLNL staff took part in another surrogate BWA test at Dugway in which a
full-scale mock office with different floor and wall materials was contaminated and
decontaminated.   The floor materials were carpet, vinyl tile, varnished oak, and painted
concrete. Wall materials included stucco, wood paneling, plasterboard, and carpet. The ceiling
was suspended ceiling tile.

The office was contaminated with 4 g of Bacillus subtilis spores by a simulated explosion using
a disseminator; then the spores were further spread by an oscillating fan.  L-Gel was used to treat
the room, then 400 swab samples were collected from throughout the office. Swabs were
quenched in sterile, buffered sodium thiosulfate solution. (This would use up any remaining
oxidizing capacity of the L-Gel. With this care in controlling the period of treatment, it is
surprising that no treatment time data were provided.)  Quenched samples were plated and live
colonies were counted.  The detection limit was 100 colony-forming units (cfu) per 4 in2 (4
cfu/cm2). L-Gel reduced the spore counts by about five orders of magnitude and did not damage
office surfaces, except that it created some surface rust on ceiling supports. In comparison,
paraformaldehyde was similarly effective at reducing the live spore counts (Raber and McGuire,
2002; LLNL, 2002).

Research indicates that L-Gel does not harm carpets or painted surfaces (LLNL, 2002), however
as noted earlier, L-Gel does have acidic properties that require the application of the material
with a stainless steel sprayer nozzle.

43.5  Concerns for the User

The pH of L-Gel is approximately 4 (LLNL, 2002).  Like other decontamination technologies
discussed in this publication, appropriate caution should be taken to avoid exposure to both the
treatment chemical and the target chemical/biological agent. Users should ensure that all
appropriate personal protective equipment are used.

Oxone is an acidic oxidizer that is corrosive to the eyes, skin, nose, and throat. DuPont states
that they observe a lmg/m3, 8-hour time-weighted average airborne exposure to Oxone (DuPont,
1998a). Oxone is incompatible with halide or active halogen compounds, cyanides, transition
heavy metals, and oxidizable organics (DuPont 1998a).

43.6  Availability of the Technology for Commercial Applications

L-Gel is not commercially available. Licensing discussions are underway between Lawrence
Livermore National Laboratory and potential vendors.

4.3.7  Advantages and Disadvantages

L-Gel has a number of advantages over other decontamination technologies. It can be used for
both CWA and BWA decontamination. As a general purpose oxidizer of organic  compounds, it
can be expected to be effective against a wide variety of hazardous industrial chemicals as well.
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It has the advantage over decontamination solutions that it is in gel form, so that it will adhere to
vertical and overhead surfaces like walls and ceilings. The oxidizing power of Oxone tends to
reduce hazardous compounds to less toxic oxidation products, but this must be ascertained on a
chemical-by-chemical basis.

L-Gel 200 has the ability to penetrate into polymeric coatings like paints and varnishes, an
important capability for decontaminating persistent CWAs that have soaked into surface
coatings. Without this ability, decontaminated surfaces will continue to become re-contaminated
as subsurface agents gradually diffuse back to the surface. This phenomenon has been referred
to as "leach-back" (see section 3.2.4), and is a potential problem for decontamination of most
surfaces, including coated or porous surfaces, and 'even  steel.

Application of L-Gel to decontaminate a surface is relatively simple: commercially-available
spray painting equipment can be used.  L-Gel's estimated cost of $1 (materials only) to treat an
area of 1m2 (11 ft2; LLNL, 2002) is quite reasonable. Applying L-Gel is simple, so labor costs
will not be high.

The disadvantages of L-Gel include: (1) It is not available commercially; (2) The residual salts
and silica significantly increase the mass of the waste produced, which may have hazardous
properties, depending on what products are formed in the oxidation by Oxone; (3) The efficacy
of the product against anthrax spores needs to be tested further to determine whether it meets
EPA's pesticide registration requirements.

4.3.8   Potential Areas for Future Research

L-Gel is being developed along two lines: (1) Penetration into surface coatings to prevent leach-
back (L-Gel 200); and (2) Making L-Gel available as an aerosol for decontamination of the
interior of ventilation systems. These improvements will be significant advantages for the L-Gel
technology.

Minimizing the mass of amorphous silica used to form the gel would be another area with
potential benefit for commercializing L-Gel. Research into the ability of L-Gel decontamination
wastes to be solidified, such as by silicate or Portland cement stabilization, would be useful for
controlling the costs of waste disposal, an important component of the overall cost of the
technology.

4.3.9   References  for Section 4.3

Battelle, 1999. Wide Area Decontamination: CB Decontamination Technologies, Equipment
and Projects - Literature Search and Market Survey. Report to the U.S. Joint Service Materiel
Group by Battelle Memorial Institute and Charles W. Williams, Inc. March 1999.

Cabot, 2002.  "Overview of CAB-O-SIL Untreated Fumed Silicas." Cabot Corp. web site:
http://www.cabot-coip.com/cws/product.nsf/PDSKE\7	EH5/$FILE/CAB-O-SIL  EH5.pdf.
Accessed November 2004.
                                          94

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DuPont, 1998a. "DuPont Oxone Monopersulfate Compound Technical Information." E. I.
duPont de Nemours and Company web site:
http://www.dupont.com/oxone/techinfo/index.html. Accessed November 2004,

DuPont, 1998b. "DuPont Oxone Monopersulfate Compound Applications." E. I. duPont de
Nemours and Company web site: http://www.dupont.com/oxone/applications/index.html.
Accessed November 2004.

DuPont, 2001. "DuPont Steps Up Efforts with UK's Antec to Battle Foot and Mouth Disease
Epidemic in Europe." March 5, 2001. http://www.dupont.com.au/'ag/news/Q70301.html.
Accessed November 2004.

LLNL, 2002. "Science and Technology Review: L-Gel Decontaminates Better Than Bleach."
April 2002. Lawrence Livermore National Laboratory web site:
hitp:/'/www.llnl. gov/stf/March02/Raber.luTnl Accessed November 2004.

Raber and McGuire, undated. Raber, Ellen; and McGuire, Raymond.  "Gel-Based Universal
Oxidation for CB Decontamination." Chemical and Biological Defense Information Analysis
Center Access No. CB-188538.

Raber and McGuire, 2002.  Raber, Ellen; and McGuire, Raymond. "Oxidative decontamination
of chemical and biological warfare agents using L-Gel," Journal of Hazardous Materials, B93:
339-352. 2002.
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5.
GAS AND VAPOR TECHNOLOGIES
5.1    Chlorine Dioxide Gas

As a biological sterilizer, chlorine dioxide (C1O2) reacts as an oxidizing agent. The predominant
target of its oxidizing action is thought to be the protein of the bacteria or virus.  Oxidation of the
protein molecules is thought to lead to functional disruption. Although the exact mechanism of
this process is not fully characterized, data exist demonstrating the antimicrobial effects of CIO2
on many common surfaces.  C102 is a relatively unique oxidizing agent in that it functions by
single-electron transfer. Unlike chlorine, it does not react with organics to form harmful
chlorinated products such as trihalomethane (THM) and chloramines.

Although its name and chemical formulation suggest a close relationship with chlorine gas (C12),
this is not the case.  C1O2 gas is not stable under high pressures, and therefore cannot be stored in
high-pressure cylinders as most gases are. C1O2 is readily soluble in water, and is stable for
extended periods of time in this form. Unlike chlorine, C1O2 remains a true gas in solution. This
lack of significant interaction with water molecules is partly responsible for the effectiveness of
C1O2 over a wide pH range.

5.1.1  Description of the Technology

Chlorine dioxide gas is generated at the decontamination site (as discussed below), and injected
into sealed building areas. It is allowed to remain in place for the required period of time,
typically on the order of 12 hours. When treatment is complete, the chlorine dioxide is
neutralized, for example, by circulating the building air through a sodium sulfite/bisulfite
solution.

Chlorine dioxide gas has been registered as a sterilant under the Federal Insecticide, Fungicide,
and Rodenticide Act (FIFRA) since 1988. However, it is not registered for use against anthrax
in building  applications.  Accordingly, EPA needed to grant crisis exemptions for its use in
response to the 2001 anthrax events. Site-specific crisis exemptions were issued for each of the
four sites that were fumigated  with C1O2 gas - the Hart Senate Office Building (HSOB); the U.S.
Postal Service's mail processing and distribution centers in Washington, DC  ("Brentwood") and
Trenton, NJ ("Hamilton"); and the Boca Building in Boca Raton, Florida. Prior to issuance of
the first exemption, conditions for chlorine dioxide fumigation were established using a trailer
test facility at Brentwood. Based upon the trailer tests and the experience with the initial
fumigations, the conditions specified on EPA's web site (EPA, 2004) for C1O2 fumigation of a
building to  treat for anthrax are:

   •   Target C1O2 concentration and exposure time:  750ppmfor 12 hours, for a total
       concentration times time multiple (CT) of 9,000 ppm-hours;
   •   Minimum temperature: 70 °F (the most recent crisis exemption, for the Trenton facility,
       specified 75 °F)
   •   Minimum relative humidity (RH): 65 percent (the most recent exemption specified
       75%).
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Although the three C1O2 fumigations indicated above utilized one particular C102 generation
technology, the gas could potentially be generated on-site by one of several technologies.
Commercial CIO2 gas generators are available in a range of sizes, although most have not been
demonstrated at the scale required to treat a large building. Many of the alternative chemical
reactions that are utilized by different vendors to generate C102 gas are illustrated in Section
5. 1.2 below (ERCO, 2004).

5.1.2  Methods for the Generation of Chlorine Dioxide

CIO2from Sodium Chlorite:

 1. Acidification of chlorite
      5 C1O2- + 4 IT - 4 C1O2 + 2 H20 + Cl~

 2. Oxidation of chlorite by chlorine
      2 NaClO2 + C12 - 2 NaCl + 2 C102

 3. Oxidation of chlorite by persulfate
      2 NaC102 + Na^O, - 2 C1O2 + 2
 4. Action of acetic anhydride on chlorite
       4 NaC102 + (CH3CO)20 - 2 C102 + NaClO3 + NaCl + 2 CH3C02Na

 5. Reaction of sodium hypochlorite and sodium chlorite (Sabre Technologies)
       NaOCl + 2 NaClO2 + 2 HC1 - 2 C1O2 + 3 NaCl + H20

 6. Electrochemical oxidation of chlorite
       C1O2" - C1O2 + e~

 7. Dry chlorine/chlorite (laboratory method)
       NaClO2 + '/2 C12 - C1O2 + NaCl (solid)

C1O2 from Sodium Chlorate:

 8. Reduction of chlorates by acidification in the presence of oxalic acid
       2 HCIO3 + H2C2O4 - 2 C1O2 + 2 CO2 + 2 H20

 9. Reduction of chlorates by sulfur dioxide (Mathieson Process)
       2 NaC103 + H2S04 + SO2 - 2 C1O2 + 2 NaHSO4

10. ERCO R-2® and ERCO R-3® processes
       NaClO3 + NaCl + H2SO4 - C1O2 + V4 C12 + Na2SO4 + H2O
11. ERCO R-5® process
       NaClO3 + 2HC1 - C102 + V4 C12 + NaCl + H2O
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12.  ERCO R-8® and ERCO R-10® processes
      3 NaClO3 + 2 H2SO4 + 0.85 CH3OH - 3 C1O2
             + 0.6CHOOH-f-0.2C02

13.  ERCO R-ll* process
      NaClO3+ '/2 H2O2 + H2SO4 -  C1O2 + NaHSO4 + H2O
                                                 Na3H(SO4)2 + H2O + 0.05 CH3OH
                                                       44 O2
In all of the above reactions C1O2 gas is one of the products generated from one of the two parent
compounds, chlorite (C1O2~) or chlorate (C1O3~).  The selection of a particular process is
determined by what materials are available, what side products are useful to the specific
industry, and the need for efficiency of the process. Individual manufacturers also have their
favorite processes and will adapt them to the situational need.

There are two basic concerns when choosing a synthesis method for chlorine dioxide. These are
the amount of gas needed and the safety concerns of the precursors and byproducts. The
electrochemical generation of chlorine dioxide from a C1O2" salt (Equation 6 above) presents the
fewest safety concerns.  Systems are commercially available that can generate from two to fifty
pounds of gas per day.

Larger quantities can be generated by both "wet" and "dry" processes. The dry process passes
chlorine gas through a solid bed of NaClO2, thereby generating pure chlorine dioxide gas.
There are two concerns with this process. The first is the transportation and storage of chlorine
gas.  Some manufacturers dilute the chlorine in nitrogen for safety reasons. The second concern
is the possible "channeling" of chlorine gas through the solid bed resulting in the release of
chlorine gas.

The wet process used for the HSOB, Brentwood, and Hamilton reacted hydrochloric acid and
sodium hypochlorite to generate chlorine gas, followed immediately by reaction of the chlorine
gas with a solution of sodium chlorite to produce CIO2 (effectively, Equation 5 above).

The last two processes are frequently used in commercial applications. The chemical reactions
between the chlorine and chlorite in the two processes are chemically identical. The "gas: solid"
process (as termed by CDG technologies) - Equation 7 above - does not use liquids. The Sabre
Technologies approach employs a two-step process within a single reactor (Equation 5), using
the chemicals in water. These reactions are presented in more detail in Table 5.1-2 later in this
report.

All three of the above processes, when operated properly, are claimed by the vendor to generate
pure chlorine dioxide gas without contaminating chlorine gas. The systems are all designed not
to have impurities in the product, allowing for accurate comparisons of the different usages of
the gas produced.  By-products of the reactions remain in either the solid or liquid phases of the
reaction.
                                          99

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5.1.3   Applications for Chlorine Dioxide

Chlorine dioxide was first discovered in the early 1800s by Sir Humphrey Davy, who reported
the reaction of sulfuric acid with potassium chlorate (Davy, 1811). The gas exists in air as a
yellow-green gas with a molecular weight of 67.5.

The vast majority of applications of chlorine dioxide utilize the gas dissolved in water. Wood
pulp bleaching is the largest use of chlorine dioxide,  accounting for an estimated 95 percent of
the chemical's production. C1O2 was used for water  odor problems at Niagara Falls in the 1940s
(McCarthy, 1945).  This first successful application led to its use in other water treatment
facilities. The widespread use of C1O2 for water purification developed later as a result of
studies in the 1970s mat linked chlorine, the preferred disinfectant of the time, with cancer
(Alavanja et al., 1980; Cantor, 1997;  Page et al., 1976). The cancer causing effect of chlorine
was linked  to the formation of THM as a disinfection by-product (Roe, 1976).  Researchers had
previously  conducted comparisons between C102 and chlorine, and determined C1O2 to be quite
effective for water purification without the generation of harmful by-products found with
chlorine (Synan et al., 1975; Bernard et al., 1976a and 1976b; Ridenour and Armbruster, 1949).

Chlorine dioxide is used to treat drinking water in approximately 5 percent of the water
treatment facilities in the United States serving more than 100,000 people (ASTDR, 2004).
However, throughout Europe, chlorine  dioxide is commonly used as a disinfectant in distribution
systems (ERCO, 2004). In drinking water supplies, chlorine dioxide is utilized as a primary or
secondary disinfectant, for taste and odor control, total trihalomethane/ haloacetic acid
(TTHM/HAA) reduction, iron and manganese control, color removal, sulfide and phenol
destruction, and Zebra mussel control.  Aqueous solutions of chlorine dioxide will release
gaseous chlorine dioxide into the atmosphere above the solution. Some newer generators
produce a continuous supply of dilute gaseous chlorine dioxide in the range of 100 to 1,000
mm Hg (abs) instead of using an aqueous solution. Aqueous solutions in the range of 0.1- 0.5
percent are common in a number of current generation technologies used in potable water
treatment processes (EPA, 1999). As in the pulp and paper industry, chlorine dioxide is
preferred over chlorine in some instances due to a reduced formation of chlorinated organic
compounds. These results led to the  EPA's suggestion in 1983 to use C1O2 as an effective
disinfectant. Partially as a result of these actions, the number of applications to use C1O2 for
water purification grew to 200-300 in the U.S. and thousands in Europe (Aieta and Berg, 1986).

While the initial commercial use for C1O2 was water purification, the utility of this gas
expanded.  C1O2 is now used in the paper processing industry (Balcer, 1981), fruit and vegetable
processing  industries (Anon, 1977; Costilow et al., 1984), and the dairy (Oliver et al., 1989),
poultry (Baran et al., 1973; Lillard, 1979; Thiessen et al., 1984), and beef (Emsweiler et al.,
1976) industries. C1O2 is not as reactive as chlorine  and therefore is more stable in wastewater
environments because it has fewer reactive targets in solution. As a result, it is also used in
industrial waste processing facilities  (EPA, 1979; Rauh, 1979; Freymark and Rauh, 1978).

The gaseous form of chlorine dioxide is the form most frequently employed as a fumigant.
Chlorine dioxide gas was registered by the EPA as an antimicrobial sterilant in the 1980s. It is

                                          100

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registered for sterilizing manufacturing and laboratory equipment, environmental surfaces, tools,
and clean rooms. It is also used in pharmaceutical research and production. Another use of
chlorine dioxide gas is in the washing of fruit and vegetables. Published research studies
indicate that chlorine dioxide gas can effectively kill Listeria monocytogenes cells on apple skins
and reduce bacteria in the stem cavity and in the calyx (Du et al, 2002).  Liquid chlorine dioxide
formulations were registered in the 1960's as a disinfectant.  It is used in this manner on pets and
farm animals, in bottling plants, and in food processing, handling and storage plants. Other
industrial uses of chlorine dioxide gas and liquid formulations include:  bleaching textiles,
disinfecting flume water, disinfecting meat and poultry, disinfecting food processing equipment,
sanitizing water, controlling odors, and treating medicinal wastes.

Whether aqueous or gaseous in form, chlorine dioxide is produced at the point of application.
Due to its instability, chlorine dioxide is not transported in pure form as a compressed gas.
Instead, it is generated from sodium chlorite or sodium chlorate (solid or aqueous materials that
are easily transported and stored), according to one of the reactions in Section 5.1.2 above.
Gaseous  chlorine dioxide is explosive at concentrations above 10% by volume in air (10 kPa, or
76 mm Hg, partial pressure at 1 atmosphere total pressure). Chlorine dioxide solutions are
normally stored cold at concentrations of less than lOg/L in order to keep the concentration of
gaseous chlorine dioxide above the aqueous solutions below the explosive limit These solutions
are corrosive to the skin and eyes, and must be handled with adequate ventilation. Protective
equipment required for the handling and application of chlorine dioxide include impervious
clothing, neoprene gloves and boots, gas-tight chemical splash goggles and face shields, and
other appropriate clothing to prevent the contact of skin with aqueous solutions or vapor.
NIOSH/OHSA-approved respiratory protection is required for chlorine dioxide concentrations
above 0.1 ppm. Self-contained breathing apparatus is required for entry and escape, and in
firefighting, when C1O2 concentrations are above 10 ppm or are unknown (Kirk-Othmer, 1993).

The application of gaseous chlorine dioxide for building contamination was demonstrated in the
remediation of the Hart Senate Office Building (HSOB), the Brentwood Mail Processing and
Distribution Center (P&DC), and the Trenton P&DC following the 2001 release of anthrax
spores through the mail.

5.1.4   Evaluation of Available Data

5.1.4.1 Data from laboratory and trailer testing

Testing by the pharmaceutical industry

Prior to the 2001 anthrax mail attacks, the pharmaceutical industry conducted extensive testing
of C1O2 for its toxic effect on bacteria, viruses and spores in pharmaceutical sterilization
applications.

In one such test program, the Sterilization Science and Technology section of Johnson &
Johnson tested the efficiency of C1O2 for the destruction of bacterial spores. These experiments
were conducted under controlled laboratory conditions using a 316-liter research sterilizer. The

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results presented in Table 5.1-1 were conducted using inlet gas pre-humidified to 70-85 percent
RH and an operating temperature of 30-32 °C, with the targets for decontamination being spore
strips containing 106 spores of B. subtilis.

Table 5.1-1. Effect of CIO2 Gas Concentration on the Rate of Inactivation of 10s B. subtilis
Spores on Paper Strips"
Exposure Time
(Minutes)
0
15
30
60
90
180
240
Fraction Nonsterile"
lOmg/L
(3,000 ppm)
NT
NT
20/20
9/20
3/60
0/20
0/20
20mg/L
(6,000 ppm)
20/20
19/20
4/20
0/60
NT
NT
0/20
40mg/L
(12,000 ppm)
19/20 .
1/20
0/20
0/20
NT
NT
NT
* The paper spore strips were placed next to the foil suture package and then overwrapped with TyvekMylar.
b NT = not tested

Based upon these data, the following were the minimal concentration-time (CT) values
determined to be required for complete sterilization of the spore strips at three C1O2
concentrations, where CT is the concentration of C102 gas in ppm multiplied by the duration of
exposure in hours.

          •   3 hours x 3,000 ppm = CT value of 9,000;
          •   1 hour x 6,000 ppm = CT value of 6,000; and
          •   0.5 hours x 12,000 ppm = CT value of 6,000.

Following these initial experiments, the Johnson & Johnson scientists postulated that the same
gas could be employed utilizing a flexible-wall barrier isolation system. The scientists
conducted geometry testing using indicator strips located at various regions within the chamber
and concluded that within "reasonable limits"., a C1O2 gas generation system is unaffected by the
size or location of targets within the structure.

The Johnson & Johnson researchers also concluded that C1O2 did not appear to leave a residue
on the sterilized surface, as is observed with some other gaseous sterilants. Not only is the
residue non-observable, but the gas itself breaks down very rapidly. Beginning with a
concentration of 3,000 ppm at start, there was only 2 ppm remaining at 15 minutes and less than
0.5 ppm after 30 minutes.  While this is a benefit for removal of C1O2 from a system after
sterilization is completed, it also clearly points to the need for a robust system that can generate
the gas at the required amounts for the required time during the sterilization process. This effect
becomes increasingly more important as larger structures are used.
                                          102

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EPA-Sponsored Evaluations of CIO2 for Anthrax Decontamination - Testing at Dugway

Chlorine dioxide fumigation was one of the remediation steps selected to decontaminate some of
the buildings impacted by the anthrax-containing letters that were introduced into the U.S. mail
system in October 2001. To help determine the appropriate C1O2 fumigation conditions for
treating treat B. anthracis, to be incorporated into the crisis exemptions for treatment of these
facilities, EPA's Regional Office in Denver, Colorado - in cooperation with EPA's Office of
Pesticide Programs (which is responsible for issuing the crisis exemption) - contracted the West
Desert Test Facility at Dugway Proving Ground to test the effects of C1O2 on a variety of dried
Bacillus spores:

    •   BAA - Bacillus anthracis var. arms,
    «   BAV - Bacillus anthracis var. vallum,
    •   BAS - Bacillus anthracis var. sterns,
    •   BGN - Bacillus subtilis var. niger,
    •   BT - Bacillus thuringiensis, and
    •   BST -  Bacillus stearothermophilus.

The data discussed and illustrated below were excerpted from West Dugway Test Center, 2002.

For these tests, spores from three strains of Bacillus anthracis (BA) and three BA simulants were
dried on either glass slides or porous filter paper and exposed to chlorine dioxide gas for 1,2,4,
6,8, and 12 hours at different relative humidities (30 to 92 percent).  Temperature was not
specifically controlled; discussions with the Dugway team indicated that they operated at
ambient temperatures (70-75 °F).

Spore preparations were cultured and a liquid slurry was applied to either porous filter paper or
glass slides and dried. Triplicate slides or filter paper were removed from the sterilization
chamber at specific intervals and cultured to determine presence of viable spores.  Experiments
were conducted at various chlorine dioxide concentrations as well as various relative humidity
values.

The Dugway team noted that - at C102 concentrations between 125 and 1,050  ppm - the relative
humidity is very important for killing all three strains of BA spores. The authors recommend a
relative humidity of greater than 70 percent for effective spore killing activity.

The authors stated that the spores dried on the glass slides were more resistant to the
remediation. This is understandable, since the spores are known to clump when wet and most
likely provided a level of insulation for spores farther away from the air interface. The spore
preparations on the filter papers were not subjected to analysis because the majority
demonstrated a six-log kill after only one hour under most conditions.  It is important to note that
the filter paper preparations were most like the  conditions at the HSOB. The spore preparation
in the envelope received at HSOB was reported to be very dry. It is possible that some spore
clumping occurred in regions where sampling was conducted, but this was likely minimal.
                                          103

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Another interesting finding from the Dugway report is that their data using spores of Bacillus
subtilis var. niger were sufficiently variable such that these data could not be included in Hie
analysis. B. subtilis v. niger is the same strain often used on the spore strips that are utilized in
the field to validate the chlorine dioxide remediation.

Figure 5.1-1 presents Trial 11 of the Dugway testing. This figure indicates that, at 30 percent
RH, a modest concentration of C1O2 has no measurable effect on viability of any spore type
tested. Figure 5.1-2 presents Trial 9 - also at 30 percent RH, but at a much higher concentration
of C1O2 (1,050 ppm) - there is still no significant loss of viability over time for any of the
organisms, except for the BGN spores. These data support the authors'  conclusion that BGN
may be the most susceptible spore tested against C1O2.  However, the Dugway tests were only a
range-finding study, using only three spore strips or carriers per run.  As a result, this analysis of
BGN's relative susceptibility is not statistically definitive.
               Trial 11 - Relative Humidity 30% - Chlorine Dioxide250 ppm
ft _. -m-n»v.i .-..*•«>.



7 •
    f
    '5 5-I-
    "a+f

                                                              DBAA  »BAV DBAS
                                                              DBON BBT

                          i.!.! ! ; | = | ••  Time (Hours)     ;

  Figure 5.1-1.  Log of Colony Forming Units (cfus) Remaining at Each Time Point
  for Trial 11; Laboratory Validation of Chlorine Dioxide Decontamination
NOTE: BAA -Bacillus anthracis var. antes, BAV - Bacillus anthracis var. vollum, BAS - Bacillus anthracis var.
sterne, BGN - Bacillus subtilis var. niger, BT -Bacillus thuringiensis, BST - Bacillus stearothermophilus.
                                           104

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                 Trial 9 - Relative Humidity 30% - Chlorine Dioxide 1050 ppm
                                                              P9AA BBAV DBAS
                                                              DBSN BBT  QBST
                                                                         12
    Figure 5,
    for Trial
                         Time (Hours)
,1-2. Log of Colony Forming Units (cfus) Remaining at Each Time Point
9; Laboratory Validation of Chlorine Dioxide Decontamination
NOTE: BAA- Bacillus anthracis \ai. antes, BAY- Bacillus anthracis var. vollum, BAS - Bacillus anthracis var.
steme, BQVf-Baciilussubtilis'var.mger, BT - Bacillus thuringiensis, BST - Bacillus stearothermophilus.
Figure 5.1-3 presents Trial 5, which utilized an intermediate concentration of C1O2, 613 ppm, at
60 percent RH. Even at this higher RH value and at a moderate concentration of C1O2, still only
BGN was susceptible to the gas.  These data support the conclusion that an RH above 60% is
needed for C1O2 to be effective in this application.

Figure 5.1-4 presents Trial 1, which utilized an intermediate concentration of C1O2, 650 ppm, at
a still higher RH of 75 percent. Under these conditions, the BGN was again most susceptible,
although the other organisms are now also showing clear susceptibility.  No viable spores were
observed of any organism after 12-hour incubation. These conditions correlate to a CT value of
7,500 ppm-hr.
                                           105

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                    Trial 5 - Relative Humidity 60% - Chlorine Dioxide613 ppm
                                                             a BAA asAV
                                                             DBGN B»BT   BBST
                                       Time (Hours)
      Figure 5.1-3. Log of Colony Forming Units (cfiis) Remaining at Each Time
      Point for Trial 5; Laboratory Validation of Chlorine Dioxide Decontamination
                    Trial t-Relatwe HurnWit¥:«%-Chlorin8;pioxide650 ppm;
                                     ;Time (Hours):

       Figure 5.1-4. Log of Colony Forming Units (cfus) Remaining at Each
       Time Point for Trial 1; Laboratory Validation of Chlorine Dioxide
       Decontamination

NOTE:  BAA - Bacillus anthracis var. ames, BAV - Bacillus anthracis var. vallum, BAS - Bacillus anthracis var.
stems, 3GN - Bacillus subtilis var. niger, BT - Bacillus thuringiensis, BST - Bacillus stearothermophilus.
                                           106

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Figure 5.1-5 clearly identifies relative humidity as the most critical parameter for the ability of
C102 to Inll Bacillus spores. At a relatively low concentration of C102, 250 ppm, and at a 90
percent RH, there were essentially no viable spores of any type remaining after two hours of
exposure. These conditions were more than twice as effective as the data with a RH of 75
percent and a greater than two-fold increase in C1O2 concentration.
              Tnal 10-RelatveHumidity 90%-ChlorineDioxide260 ppm
 Figure 5.1-5. Log of Colony Forming Units (cfus) Remaining at Each Time Point
 for Trial 10; Laboratory Validation of Chlorine Dioxide Decontamination

NOTE:  BAA - Bacillus anthracis var. antes, BAV - Bacillus anthracis var. vollunt, BAS - Bacillus anthracis var.
sterne, BGN - Bacillus subtilis var. niger, BT - Bacillus thuringiensis, BST - BaciUus stearothermophilus.
These experiments conducted at Dugway Proving Grounds clearly demonstrate the importance
of relative humidity, time and C1O2 concentration for the killing of dried Bacillus spores. The
Dugway testing was not completed in time to help define the concentration, time, and RH to be
specified in the crisis exemption allowing C102 fumigation during remediation of the HSOB.
However, these data validated the values selected for the HSOB fumigation, and have supported
the conditions specified for subsequent fumigations.

The data presented above were for spores dried on glass slides. The scientists also conducted
parallel experiments using the same spore slurry dried on filter paper. The spores on the filter
paper possibly had a greater exposed surface area, since they were adhering to the three-
dimensional fiber matrix of the paper. The data obtained from the filter paper indicated almost
100 percent killing of all spore types within one hour under almost all experimental conditions.
It was suggested that the higher kill rate on the paper might be due to the potential ability of the
                                           107

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gas to penetrate the paper from both sides, whereas the spores applied to glass slides could be
attacked only from one side. Another possibility is that clumping of the spores may have been
more likely on the glass slides, where the high-concentration spore slurry would have resided in
a pool as the liquid dried; the clumps could have been more resistant to the C1O2.

EPA-Sponsored Evaluations of C1O2 for Anthrax Decontamination - Washington, DC, Test
Trailer

       Since the Dugway testing could not be completed before the decisions had to be made
regarding C1O2 fumigation conditions for the HSOB, a brief series of tests was conducted in the
Washington, DC, area to help define these conditions.

The tests utilized a trailer-mounted Sabre Technologies C102 generator, piped to fumigate an
adjacent empty truck trailer (Schaudies et al., 2003).  Spore strips and Steri-charts containing
three 5. anthracis surrogates - B.  subtilis, B stearothermophilus, and B. thuringienisis - were
placed inside the trailer.  The average C1O2 concentration to which the indicators were exposed
was varied between 200 and 2,300 ppm over the series of 12-hour runs, giving CT values
ranging from 2,000 to 28,000 ppm-hr. The average relative humidity inside the trailer was
varied between 65 and 79% for different runs. The average temperature inside the trailer was
held at 75 to 78 °F. Prior, preliminary lab tests conducted by DoD's Defense Advanced
Research Products Agency (DARPA) had suggested that a CT above 4,000 ppm-hr, an RH
above 75%, and a temperature above 75 °F would be preferred; the range of conditions for these
trailer tests were selected on that basis.

Based on the results of these tests - and subsequent analysis - it was decided that the target C1O2
fumigation concentration should be 750 ppm for 12 hr (CT = 9,000 ppm-hr), and that the RH and
temperature should be "as high as possible" (Schaudies et al., 2003).  Of the three spores tested,
B. subtilis was the most susceptible to the C1O2 gas.

EPA-Sponsored Evaluations of CIO2 for Anthrax Decontamination - Beltsville Maryland

After fumigation of the HSOB, EPA conducted a series of seven fumigations in a trailer at the
U.S. Department of Agriculture's (USDA) Agricultural Research Center in Beltsville, MD to
decontaminate U.S. mail and private carrier packages transferred from the P Street Warehouse,
as well as artifacts, critical items (items determined to be too important for destruction), and
other items that were not treated with ethylene oxide sterilization. The two photographs in
Figure 5.1-6a and 5.1-6b illustrate the chlorine dioxide generation system and the interior set up
at the Beltsville remediation facility.

The first six runs were conducted  between March 22 and March 28, 2002.  The  seventh run was
conducted on April 10 and 11, 2002.  The target exposure concentration was 1,000 ppm for 9
hours in runs one through six.  In the seventh run, the target C1O2 concentration was 450 ppm for
a longer exposure time of 20 hours. Uncontaminated packaging materials were included in the
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 Figure 5.1-6a. Chlorine Dioxide Genera-
 tion System at Beltsville, MD
5.1-6b.  Interior Operations at OO2 Test
Facility at Beltsville
last run to determine the penetration efficiency and other effects of C1O2 on various materials.
The target temperature for all runs was approximately 80 °F, with a target relative humidity of
80-85 percent. Actual measurements were taken for all three parameters at frequent intervals
during each run and are presented and discussed below.

Spore strips were used to assess the effectiveness of the fumigations. As with other fumigations,
B. subttlis and B. stearothermophilus were used. A combination of spore strips and Steri-charts
were placed in 30 designated sampling locations in the treatment trailer during each run. The
effectiveness of each fumigation was assessed using a total of 255 spore strips. Each array
consisted of a negative control  strip, three B. subttlis spore strips and one B. stearothermophilus
spore strip. Steri-charts were included at half of the sampling locations., along with an additional
negative control  strip.  Spore strips were in aTyvek sleeve and all samples were handled with
powder-free, sterile, nitrile gloves and alcohol-sterilized tweezers to prevent cross-
contamination. Each spore strip included a location code and a unique identification number.
Positive controls from each Steri-chart were used to assess viability of the spores on the test
strips. Therefore, they were removed and placed in a pre-labeled key envelope prior to
positioning of the charts  and were never exposed to C1O2 gas.

Sporicidal efficiency was calculated for each individual run for each of the two indicator
organisms. .The use of the steri-chart strips allowed for quantification of kill efficiencies of up to
108 for B. subtilis and 107 for B. stearothermophilus. Fractional exponents were calculated based
on the raw data.  In some cases there was positive growth at 106 with both higher concentrations
being growth negative. This could be the result of clumping on the spore strip, or handling
and/or laboratory error.  If the sample was subsequently  analyzed by culture and the resultant
organisms were not the indicator species, the culture data were considered growth negative.
There were no cases in which growth of the target organism occurred after exposure to the lower
concentrations of chlorine dioxide fumigant.
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Two Beltsville 3D bar graphs were generated illustrating five factors: relative humidity,
temperature, concentration of chlorine dioxide integrated over time (CT), log kill rate, and
organism type (Figure 5.1-7, B. subtilis, and Figure 5.1-8, B. stearothermophilus). The graphs
were generated from data in the table inserts shown on the figures. The graphs present kill rate,
concentration of chlorine dioxide integrated over time (CT), and percent relative humidity
(percent RH) on three axes. The fumigation temperatures are color coded in incremental ranges
from <75.1 °F (blue) to >85 °F (red). The organisms are identified with different patterns on the
bars of the graph.  B. subtilis has vertical lines and B. stearothermophilus has horizontal lines.
The same scaling was used on the axes of the two graphs to allow for easier comparison.

Temperature and Relative Humidity Data. Temperature and relative humidity values were
calculated by taking the average of the readings for each data run from two machines, Model No.
8762, for the "Black" version (Serial No.: 01120527) and the "Grey" version (Serial No:
01120217).  The temperature and humidity values used ranged from the time of initial treatment
of C1O2 to the final reading. After the average was obtained for each machine, an average of the
two values was taken for the final temperature and relative humidity value listed for each test
run.

Concentration Data. Concentration values were calculated by taking the average of the final
concentration readings  of the four sample locations for each test run.

B. subtilis var. niger was originally selected as a surrogate organism, because of its unique
property of producing an orange color on agar growth plates. This makes the identification of
this particular strain relatively easy in a subsequent culture analysis.

Run#l
The first run resulted in a chlorine dioxide CT value of 9,920 over a 9.7-hour period with an
average concentration of 1022 ppm/hr.  The average temperature was 85.7 °F with an average
RH of 86 percent.  All of these values were within the target range. The kill rate for B. subtilis
was 107 5 and the kill rate for B. stearothermophilus was 10s. These results were consistent with
earlier data in which the killing efficiency for B. subtilis was generally an order of magnitude
greater than that achieved for B. stearothermophilus under identical conditions.

Run n
The second run resulted in a relatively high chlorine dioxide CT value of 15,345 over a 12-hour
period with an average concentration of 1,278 ppm/hr.  The average temperature was 82.4 °F
with an average RH of 85 percent. All of these values were within the target range. The kill rate
for B. subtilis was 10s and the kill rate for B. stearothermophilus was also 106.  These results
were inconsistent with  earlier data in which the killing efficiency for B. subtilis was generally an
order of magnitude greater than that achieved for B. stearothermophilus under identical
conditions.
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                         RH vs. CT vs. Kill Rate
Beltsville—£. subtilis
Test Run
1
2
3
4
5
6
7
%RH
86,0
82.4
81.1
83.8
83.8
86.3
79.3
Temp (*F)
85.7
84.6
84.4
85.7
84.1
87.4
80.2
CT
9,920
15,345
12.578
9.772
10.325
12.722
14.374
Kill Rate
107'5
10s
1072
10s
10"
107!
10"
Run Duration
(hours)
9.7
12.0
9.0
7.7
8.0
9.0
21.0
CT/Hour
1022
1278
1397
1269
1290
1413
684
Figure 5.1-7. Beltsville data for Bacillus subtilis spore strip analysis at various conditions
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Beltsville—& stearothermophilus
Test Run
1
2
3
4
5
6
7
%RH
86.0
82.4
81.1
83.8
83.8
86.3
79.3
Temp OF)
85.7
84.6
84.4
85.7
84.1
87.4
80.2
CT
9,920
15.345
12,578
9.772
10.325
12,722
14.374
Kill Rate
10'
106
10"
10"
1068
10'
107
Run Duration
(hours')
9.7
12.0
9.0
7.7
8.0
9.0
21.0
CT/Hour
1022
1278
1397
1269
1290
1413
684
   75.1-77.5
   77.6-80.0
   80.1-82.5
   82.6-85.0
     >85.0
Figure 5.1-8. Beltsville data for Bacillus stearothermophilus spore strip analysis at various
conditions.
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operational ranges tested at Beltsville. In fact, one of the best kill rates was obtained at the
lowest temperature and relative humidity. This final run also employed a significantly lower
absolute concentration of chlorine dioxide, but with an increased exposure time resulting in an
increased final CT value. These conditions also resulted in an excellent killing efficiency.
Comparisons Between Different Operations

The data presented above represent chlorine dioxide generated via the three methods mentioned
previously. The Johnson and Johnson experiments used gas generated as a result of passing
dilute chlorine gas through a packed bed of flaked NaClO2. The Dugway report used the
electrolysis system, and the Washington DC area EPA data were generated by the solution
method by Sabre Technologies. All of the systems are believed to have generated fairly pure
chlorine dioxide. While all of the systems demonstrate that the chlorine dioxide is capable of
killing bacterial spores, the results do vary. It is possible that this variability is due to
differences in temperature and humidity for the different experimental conditions. Uncertainty
exists because the specific temperature and humidity measurements were not provided. Johnson
and Johnson gave a humidity range of 75-90 percent relative humidity and the Dugway test did
not present temperature data. The data that are presented are very compelling that chlorine
dioxide is  an effective agent for killing of spores if used correctly.

Materials Compatibility and Residue

Chlorine is known to react with an extensive variety of compounds, primarily through oxidation
reactions,  but it also participates in addition and substitution reactions (EPA, 19.81).  C1O2 has a
much more limited reactivity towards organics (Rav-Acha, 1984; Masschelein, 1980) and as
such remains available as a biocide even in relatively dirty environments.

The bleaching effect of the gas is
more apparent in synthetic rather
than natural fibers. Most paints are
relatively unaffected by the gas, but
photographic emulsions are
susceptible to bleaching as
illustrated in Figure 5.1-9.

Figure 5.1-9 illustrates the effect of
C1O2 on two separate types of
photograph color images.  The
small strip was not exposed to
C1O2, the bottom portions were
exposed to 700 ppm C1O2 for 10
hours at 75 °F at 75 percent relative
humidity.  This experiment was
conducted by the U.S. EPA
Emergency Response Team at a   .
Washington D.C. test trailer in       Figure 5.1-9.  Bleaching Effect on Photographic
November 2001.                   Materials
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Chlorine dioxide is a strong oxidizer but does not chlorinate organic compounds or amines the
way that chlorine gas does.  Chlorine dioxide might penetrate into some materials - such as
porous materials, plastics, and rubbers - resulting in an "off-gassing" period.  For example, a
video cassette tape exposed to 500 ppm of chlorine dioxide for eight hours still had a distinctive
odor three weeks after exposure (personal communication: R. Paul Schaudies). An added
advantage of chlorine dioxide over other gas sterilants, such as paraformaldehyde, is that it
leaves no visible residue.

5.1.4.2 Experience with field famigation of buildings

Experience at the Hart Senate Office Building

On October 15,2001, an anthrax-containing letter was received in Senator Daschle's suite in the
Hart Senate Office Building (HSOB).  A second such letter, to Senator Leahy, was stopped in
the mail processing system after the Daschle letter was received, and was discovered before it
could be delivered. The letter to Senator Daschle resulted in significant contamination of the
suite itself by anthrax spores.  Spores were also drawn into the return ducting of the air handling
system serving the suite (and adjoining suites), and were transported to some other HSOB suites
and common areas by building air movement or occupant activities. Spores were also found in
mail handling facilities in the HSOB and in other nearby Government buildings, resulting from
the processing of the Daschle or Leahy letters, or of other letters that had been cross-
contaminated by those two. Collectively, the buildings near Capitol Hill that were impacted by
these two letters are referred to as the Capitol Hill Anthrax Site.

As was to become the pattern in subsequent building anthrax remediations, initial remediation
activities included sealing of the HSOB to prevent further spread of the spores. Environmental
sampling was conducted to define the extent of the contamination, demonstrating high levels of
contamination in multiple areas within the Daschle suite, and lesser levels of contamination in
the return ductwork of the air handling system and in other HSOB suites and common areas.
Lesser levels of contamination were also found in the affected mail facilities within the Capitol
Hill Anthrax Site.

EPA evaluated a number of alternative decontaminating agents for treatment of the Capiol Hill
Site, including various liquids, foams, gels, and gaseous sterilants. Based upon evaluation by an
interagency committee of advisors, it was decided to use a gaseous sterilant as a central
component of the remediation strategy.  For various reasons, including its penetrability, chlorine
.dioxide was selected as the gaseous fumigant. Initially, EPA considered fumigation of the entire
HSOB (about 10 million cubic feet of volume).  But ultimately, a tiered approach was settled
upon, wherein the initial fumigation would address only the Daschle suite (93,000 ft3) - the most
highly contaminated area. A decision regarding how to treat any other areas would be made
based upon further environmental sampling, and the experience in the Daschle suite.

Using this approach, it was ultimately decided that - in addition to the Daschle suite itself- the
one other space to be fumigated with C1O2 would be the return ductwork for the air handler
(3,000 ft3). All of the other areas in the HSOB, and other affected buildings, were  decontami-
nated using various topical treatments (in particular, with aqueous C1O2 or sodium hypochlorite).
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This was the first time that gaseous C102 sterilization had been utilized in microbial decontami-
nation.of a building.

Prior to the HSOB fumigation, all available experimental data had been obtained under
controlled laboratory conditions in sealed chambers that would fit within a single room of the lab
building. While mathematical calculations appeared to support the feasibility of the C1O2
fumigation approach for the remediation of large buildings, such large-scale field fumigation
using C1O2 had not previously been attempted. As discussed in Section 5.1.4.1, in preparation
for the HSOB remediation, EPA conducted testing in a trailer in Washington, DC, and initiated
controlled laboratory  experiments at Dugway Proving Ground, to help define the appropriate
fumigation conditions  for this new application.

The field experiments in the Washington, DC, trailer suggested that C1O2 fumigation with a CT
of 9,000 ppm-hr (750 ppm for 12 hr), with a temperature above 75 degrees Fahrenheit, and with
a relative humidity above 75 percent, would provide a six-log kill of Bacillus anthracis spores.
These conditions were consistent with prior laboratory results.

The first step in the fumigation process was to seal the area to be fumigated, to contain the
fumigant (as well as to prevent the anthrax spores from being transferred into other areas of the
building or outdoors).  Comprehensive sealing of Senator Daschle's suite was achieved using
heavy plastic sheeting around the suite's interior perimeter, to isolate it from the remainder of
the building. Exterior windows were covered and sealed with light-blocking material, to isolate
the suite from outdoors, and also to prevent UV radiation from entering the space, since sunlight
causes decomposition of C102. Other openings through the exterior shell were also sealed.

Relative to the fumigation activities at most of the subsequent remediation sites, the extent of
source reduction in the Daschle suite prior to fumigation was modest.  Except in the area
immediately around where the anthrax-containing letter was opened, few building materials or
furnishings were removed. Ceiling tiles, carpeting, furniture, etc., were largely left in place for
decontamination by the fumigant.  The exception was that selected valuable artifacts and critical
items were removed for off-site treatment in an ethylene oxide gas sterilization chamber.  Also,
paper items were removed from surfaces, drawers, and cabinets, and sent either to an off-site
ethylene oxide sterilization chamber, or to a medical waste incinerator. Topical cleaning of suite
surfaces prior to fumigation - using liquid agents (such as  aqueous C1O2 or bleach), or
vacuuming using a high-efficiency particulate air (HEP A) filter - was limited, with the
expectation that the gaseous  C1O2 fumigation would adequately sterilize all surfaces.

Chlorine dioxide was generated using the Sabre Oxidation Technologies process. This system
utilizes Equation 5 in Section 5.1.2.  Sodium hypochlorite  (bleach) solution is first reacted with
HC1 to produce chlorine gas (cy, followed immediately by  reaction of this chlorine with
sodium chlorite solution to produce the C1O2 in aqueous solution. The presence of free chlorine
is minimized or avoided by utilizing excess sodium chlorite.
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The trailer-mounted C102 generator and its ancillary equipment was located outside the Hart
Building, at street level below the suite. The aqueous C1O2 solution was pumped up to the suite
through exterior piping, and then passed through air strippers inside the suite to release the
gaseous C1O2 into the sealed space.

Prior to the introduction of C102 during fumigation, the RH and temperature in the suite were
first raised to the target values (^75%, ^75 °F) by 12 heaters and humidifiers placed within the
space (Schaudies, 2003). Maintenance of the high relative humidity proved to be an operational
challenge in this initial application of this technology to building fumigation, revealing the
humidification capacity required for this purpose. Following the humidification phase, feed of
aqueous C1O2 solution to the air strippers was initiated (the "conditioning" phase). The "CT
clock" for the fumigation was started after the C1O2 concentration in the space reached the
desired level.

In an effort to achieve uniform mixing of the C102, the steam, and the heated air throughout the
suite, nine box-type mixing fans were operated during the fumigation process.

Gas samples for analysis were taken at 16 locations throughout the suite on 10- to 15-minute
intervals, to verify whether C1O2 concentrations were holding at the required level, and whether
the required CT of 9,000 ppm-hr was being achieved.  The results showed that the average CT
throughout the suite during the fumigation period exceeded the minimum (averaging 9,600 ppm-
hr in one part of the suite, and 10,900 ppm-hr in the other part),  although there were individual
sampling locations where the CT dropped below the target value (as low as 6,000 ppm-hr at one
location) (Schaudies and Robinson, 2003).

Also, temperature and RH probes were installed at a number of locations throughout the suite to
allow the heaters and humidifiers to be adjusted to maintain the objectives of *75 °F and *75%
RH. Unfortunately, these probes failed to function during the fumigation due to an electrical
problem, and the temperature and RH measurements had to be made manually by staff inside the
space.  The temperatures generally met the target, ranging between 72 and 77 °F. The RH met
the target in one part of the suite (ranging between 83 and 89%), but fell-below the target in the
other part (ranging between 57 and 75%).

Throughout the fumigation process, EPA's Environmental Response Team (ERT) monitored the
ambient air in the area around the HSOB using a mobile monitoring van, to confirm that
hazardous amounts of CIO2 gas were not escaping into the environment.  A maximum ambient
concentration of 25 ppb was detected over a very short time period; 100 ppb would have been
required to shut down the generator.  In addition, stationary air monitors placed in the area
surrounding the HSOB did not measure significant levels of C1O2 during the fumigation.

After the suite had been fumigated, the residual C102 gas in the suite was removed by circulating
the suite air through a scrubbing solution. This was accomplished by switching the liquid in the
in-suite air strippers from aqueous C1O2 to the scrubbing solution, thus converting them from
C1O2 emitters into scrubbers.  Natural decay of the C1O2 hastened the removal process.
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Following EPA's issuance of a crisis exemption under FIFRA for the use of gaseous C1O2 in this
application, the fumigation of Senator Daschle's suite took place over a period ending on
December 2,2001. The effectiveness of the fumigation was determined in two ways:

    1.  Spore strips containing surrogates for the anthrax (Bacillus anthracis) spores. Over
       3,000 spore strips containing B. subtilis, B. cereus, B. thuringiensis, and B.
       stear other mophilus spores were distributed around the suite - attached to walls, floors,
       and furniture, and placed under desks.  The spore strips were positioned to verify whether
       a sufficient concentration of C1O2 had been maintained for a sufficient time and at a
       sufficient relative humidity at each location in the suite to kill the surrogate spores on the
       strip.

    2.  Environmental sampling to verify whether any surviving B. anthracis spores remained at
       the sampling location. Environmental sampling methods included: surface sampling,
       using wet wipe and vacuum techniques; and aggressive air sampling, i.e., high-volume
       sampling of the suite air after room surfaces had been agitated (blown) in an effort to re-
       suspend any spores that might have been present.

The results from a number of the spore strips were positive, indicating that the concentration-
time-RH-temperature conditions at some locations may not have been sufficient to kill all of the
surrogate spores on the strip. Subsequent testing suggested that some of these apparent positives
may have been due to secondary contamination of the spore strips at various points in the
process: a) during the fumigation, when entries were made into the suite; b) during the post-
fumigation collection and handling of the strips; and c) during analysis in the laboratory.

The results of the environmental sampling, performed after removal of the spore strips, indicated
a highly significant reduction in contamination of the suite.  However, a small percentage of the
samples were positive for the growth of B. anthracis spores. Therefore, surface cleaning with
aqueous chlorine dioxide was then performed in the suite.  (As discussed under Section 3,2.4 of
this report, EPA had issued a crisis exemption under FIFRA, allowing the use of aqueous C102
against anthrax in this application.)

Following application of the topical aqueous solution, the final environmental samples in the
suite were all negative for growth of anthrax spores.

As indicated previously, the return ducting and filter in the air handling system serving the
Daschle suite had also tested positive for anthrax spores, and was fumigated with C1O2. The
filter was removed.  The return ductwork from the Daschle suite - which connected to the
returns from other suites that had not been impacted - was isolated from these other returns.
Feed lines from the CIO2 gas generator and the steam generator were connected into the return
duct in the suite, and an exhaust fan was connected at the other end of the return ducting (i.e., by
the air handler, several stories above the suite). The ducting was fumigated by using an exhaust
fan to draw C1O2 gas and steam through the contaminated section of return ducting. The C1O2-
containing outlet from the exhaust fan was designed to pass through a scrubber to remove the
C1O2 before being released.
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Chlorine dioxide concentrations were measured at nine sampling locations throughout the
ductwork and air handling system, and temperature and RH probes were installed at seven
locations, to verify whether the concentration and environmental targets were met. Also, a total
of 440 surrogate spore strips were suspended in the air stream at 11 locations within the air
handling system to help assess fumigation efficacy.

Unfortunately, the first attempt at fumigating the return duct was unsuccessful due to difficulties
in maintaining the required fumigation conditions. As a result, some spore strips showed
incomplete kills of the surrogates. Some sections of the ductwork were wiped with aqueous
C1O2 solution, and the ducting was fumigated for a second time on December 28-31,2001.

Subsequent environmental sampling showed no growth of anthrax spores in any of the samples.
The HSOB was  cleared for re-occupancy and re-opened on January 22, 2002.

Experience at the USPS Brentwood Processing and Distribution Center (Curseen-Morris)

The letters to Senators Daschle and Leahy, containing weapons-grade B. anthracis spores, were
processed through the U. S. Postal Service's Brentwood Processing and Distribution Center
(P&DC) in Washington, D.C.  This facility was the primary Federal mail processing center for
the Washington area. Some of the very fine spores escaped from the envelopes as they passed
through the high-speed sorting machine on Line 17 and other postal equipment.  The
contamination was spread in large part through the operation of the mail equipment, and through
the routine use of compressed air to clean the machines of dust and debris. The Brentwood
P&DC was closed on October 22,2001, after four workers at Brentwood developed inhalational
anthrax. Environmental measurements to determine the extent of the contamination revealed the
greatest number of positive samples at Line 17 and at the two adjacent mail sorting machines,
Lines 16 and 18.

The lessons learned at the HSOB were valuable in guiding the Postal Service's efforts for
remediation of the Brentwood P&DC.

The building was tightly sealed, to prevent B. anthracis spores from migrating from the facility
prior to remediation.  This sealing also served to prevent the large volume of C102 gas that
would be inside this building during fumigation from escaping out into the adjoining
neighborhoods.  And it served to prevent outside light from entering the building during
fumigation, since C1O2 gas decays quickly in the presence of UV light. In general, plywood or
foam board was attached over exterior windows, doors, and other large openings in the exterior
shell, with caulking and duct tape to ensure a good seal. Unintended openings in the building
shell - e.g., seams between the roofing and the exterior wall - were caulked.

The initial remedial efforts at Brentwood included a series of source reduction steps and spot
decontamination efforts (Princiotta, 2003; Canter, 2004).  A significant amount of porous and
non-porous material was treated  with bleach, then packaged within the facility and taken off-site
for disposal as infectious waste.  Materials thus treated and removed included, for example,
some ceiling tiles; carpeting was  generally left in place. Some other materials, such as non-
porous postal carts and  other rolling stock, were decontaminated with bleach in accordance with
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the crisis exemption granted by EPA for the use of this aqueous product, and then sent to other
postal facilities for re-use. Surface cleaning of mail sorting machines with bleach was also
conducted.

Following topical bleach treatment of Lines 16,17, and 18, additional environmental sampling
was performed.  This sampling continued to show B. anthracis contamination, but at lesser
levels.

Lines 16,17, and 18 were then enclosed in a tent of plastic sheeting, and fumigated with gaseous
C1O2 in July 2002. As at HSOB, the selected fumigation conditions inside the tent were
specified as: C1O2 concentration ^ 750 ppm; exposure time 12 hours; RH ^75%; and
temperature ;>75 °F. Surrogate spore strips were used to estimate the efficiency of this
fumigation.  Greater than 99% of the spore strips were negative for growth of spores following
the fumigation.

Following this focused treatment of the most contaminated areas, the entire building was
fumigated with a gaseous sterilant. In view of the experience at HSOB, it was again decided to.
use C1O2 as the fumigant.  However, in this case - rather than treating only selected sections of
the building, as had been possible with Senator Daschle's suite - the decision was made at
Brentwood to fumigate the entire  building (the entire 14 million cubic feet) at one time. This
decision was based on the widespread contamination within the Brentwood facility, and the open
nature  of most of the facility.

The Sabre Oxidation Technologies process was again utilized to generate the C102 gas for the
fumigation, as it had been at the HSOB. However, because the Brentwood facility had 150 times
the volume of the Daschle suite, the trailer-mounted gas generator used as HSOB was no longer
adequate. A new, larger gas generator was built for this purpose. Also, more substantial
ancillary  equipment was required  generate the steam needed for humidity control, to provide the
quantities of NaOCl, HC1, and NaC102 needed to generate the required amount of C1O2, to
distribute the aqueous C1O2 throughout the building and  air-strip it inside the building, to provide
the quantities of Na2HSO3 and NaOH needed to generate the Na^Oj required to scrub the C1O2
gas from the building, and to handle the liquid wastes generated. (The chemistry involved with
the Sabre process was discussed previously in connection with the HSOB remediation.)

As in the case of the HSOB fumigation, the objective was to maintain the building at a C1O2
concentration at 750 ppm or above for  12 hours (for a total CT of at least 9,000 ppm-hr), at a
relative humidity greater than 75% and a temperature of 80 DF.

At Brentwood, two large exhaust  fans (referred to as "negative air units", or NAUs) were used to
maintain the entire building at negative pressure throughout the fumigation, to prevent escape of
the CIO2  into the ambient air. The objective was to control operation of the NAUs such that the
average pressure across the building shell at the five most positive pressure measurement points
was at least -0.02 inches of water (i.e., that the interior averaged at least 0.02 in. lower in
pressure than the outdoors). The  C102-containing exhausts from these two NAUs were passed
through HEPA filters, sodium sulfite scrubbers, and carbon sorption beds (which served as a
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polishing step for ClO2-removal, and as back-up in the event of scrubber failure). The objective
was to reduce the C102 concentration in the NAU exhausts to 5 ppm or less.

Modeling calculations showed that - if the NAUs failed to maintain negative pressure in the
building - the resulting leakage of high-ClO2 building air into the ambient could theoretically
result in ambient C102 concentrations of 1 ppm half a mile from the site. While this is below the
level considered Immediately Dangerous to Life and Health (5 ppm), it is above the OSHA/
ACGIH 15-minute standard of 0.3 ppm, and underscores the importance of proper functioning of
the NAUs.

In view of these concerns, three tests were conducted on one of the NAUs prior to fumigation.
The test objectives were to ensure that the sodium sulfite scrubber would function effectively
during the full-scale fumigation., and that the carbon bed alone had the capability to maintain the
exhaust below 5 ppm in the event of a catastrophic failure of the scrubber.  Following
improvements to the scrubbers and the carbon beds based upon these tests, the concentration
objectives were successfully achieved.

Following the modifications of the NAU scrubbers and carbon beds, a practice run was
conducted at low C1O2 concentration to confirm that all systems were functioning properly. This
test demonstrated that a several-hundred-ppm C1O2 concentration could be maintained
throughout the building for several hours, that the NAUs  could achieve and maintain negative air
pressure inside the building, and that NAU exhaust concentrations could be maintained below 5
ppm.  Based upon the results of this low-level run, EPA issued a crisis exemption under FIFRA
to enable the full fumigation to proceed.  The fumigation was successfully completed on
December 14-15, 2002.

Throughout the fumigation process, EPA's Environmental Response Team (ERT) monitored the
ambient air in the area around the HSOB using a mobile monitoring van, sampling for C1O2.
Measurements were also made at the Brentwood fence-line, and on the building itself. To
protect the adjoining neighborhoods, the generator was to be shut down if ambient levels of C1O2
were at or above 100 ppb for two consecutive 15-minute sampling periods at any of these
ambient monitoring stations. The ambient concentration never reached 100 ppb.

As at HSOB, the success of the fumigation at Brentwood was determined through:  1) surrogate
spore strips throughout the building, to verify that fumigation conditions had in fact been
maintained adequately to kill surrogate spores; and 2) environmental samples taken after
fumigation, including both surface sampling and aggressive air sampling. The U.S. Postal
Service final report indicated that greater than 98% of the spore strips showed complete kills of
the surrogate spores, and that all environmental samples were negative for growth of B.
anthracis spores. Based on these results, the Environmental Clearance Committee
recommended in September 2003 that the facility (now named the Curseen-Morris P&DC) was
safe for re-occupancy.
                                          122

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Experience at the USPS Hamilton Processing and Distribution Center (Trenton, NJ)

Anthrax-containing letters to the New York Post and to the NBC-TV network offices in New
York City were processed through the Hamilton P&DC on September 18, 2001. The two letters
to Senators Daschle and Leahy were also processed through Hamilton on October 9,2001. After
five workers at Hamilton were diagnosed with cutaneous or inhalational anthrax, the facility was
closed on October 18,  2001.

Hamilton has a volume of about 6 million cubic feet, less than half the size of the Brentwood
facility.  The decision was made that - as with Brentwood - a central component of the Hamilton
remediation would be C102 fumigation of the entire building at one time, using the Sabre
Oxidation Technologies process.  The fumigation process at Hamilton was postponed until after
the cleanup, at Brentwood was completed, so that the C1O2 generators and much of the ancillary
equipment that had been used at Brentwood could be transported to the Hamilton site and used in
this fumigation. A number of refinements were implemented at Hamilton based upon the
Brentwood experience.

The extensive experience at the two fumigations at the HSOB and at Brentwood enabled a more
efficient remediation at Hamilton.

The building was extensively sealed, with the aid of thermal imaging. Exterior doors and
windows were sealed with foam insulation board and layers of plastic sheeting.  All openings in
the building shell were sealed with silicone caulk (or expanding foam) and tape, including seams
around the door and window covers, expansion joints in the exterior walls, utility penetrations
through the shell, and gaps where the roof met the walls. Exhaust vents and the building's sewer
system were sealed.  All HVAC penetrations in the shell - including air intake and exhaust
vents - were sealed.  The sealing of exterior windows and glass doors serves not only to prevent
spores and C1O2 from escaping into the ambient air, but also prevents UV light from entering the
building and increasing the decay rate of the C102.

Significant source reduction activities were conducted at Hamilton prior to fumigation. Critical
items (e.g., cash, mail, key files) were packaged and removed for off-site sterilization. Other
porous materials were removed for disposal, including carpeting, upholstered furniture, ceiling
tiles, some cubicle walls. Such porous materials were treated with modified (pH-neutral) bleach
(sodium hypochlorite) prior to packaging and shipment off-site. Frame walls were left in place.

Many surfaces were cleaned by HEP A vacuuming and/or by  wipe-down with modified bleach
solution. Extensive efforts in this regard were made to clean  the mail handling equipment that
processed the four anthrax-containing letters. Special focus was placed on those sites within the
building where initial environmental sampling had identified a problem, or where employees had
been stationed who had contracted either cutaneous or inhalational anthrax.  To the extent
practical, the HVAC distribution ducting was cleaned with modified bleach, and the existing
HVAC mixing boxes removed and replaced. The removed mixing boxes were cut into pieces,
cleaned with modified bleach on-site, packaged, and shipped  for disposal.
                                          123

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As in the prior fumigations, the target at Hamilton was to maintain at least 750 ppm C102 for a
period of 12 hours (for a CT of 9,000 ppm-hr), at an RH at or above 75%, and a temperature at
or above 75 °F.

The C1O2 was generated outside the building by the same dual (primary plus back-up) Sabre
reactor system used at Brentwood, reacting aqueous NaOCl with HC1 to produce C12, followed
instantaneously by reaction of this chlorine with NaClO2 to produce aqueous C102. Hie aqueous
C102 was pumped to 12 air strippers distributed inside the building, releasing gaseous C102 into
the building air.  Relative humidity and temperature were controlled by steam from a boiler
outside the building. During fumigation, the building was held at negative pressure, to avoid
escape of the C102 to the outdoors. This negative pressure was maintained by two large exhaust
fans ("negative air units"), which exhausted the ClO2-containing building air through a sodium
sulfite scrubber, with a back-up carbon sorption bed, in order to reduce the stack exhaust
concentration to the 1.8 ppm required by permit.

Between 300 and 400 fans, located throughout the building, were utilized in an effort to ensure
uniform mixing of the C1O2 during fumigation. These included 5,000 acfm tube-axial fans and
2,000-5,000 acfm box fans, as well as the building's ceiling fans. The building's internal
HVAC air handlers were also used to assist in the distribution, in that C1O2 released by Sabre's
emitters was drawn into the air handlers' return ducting, and distributed throughout the zone
served by each air handler.

The postal machinery inside the building was wired to be operated remotely during the
fumigation process, in an effort to ensure that all components of the equipment were exposed to
the C1O2 gas.

 Consistent with the fumigations at HSOB and Brentwood, this fumigation was conducted in
four steps:

   1) Humidification, in which steam from the exterior boiler (and, as necessary, heat from the
      building's heating system) were used to bring the building up to the required conditions
      (* 75% RH, ^ 75 °F). The building had to be held at those conditions throughout for at
      least one hour before C1O2 was introduced.

   2) Conditioning, in which aqueous C1O2 introduction into the building began, and the indoor
       concentration was raised to the level at which the CT clock would start running.  In this
      case, the minimum concentration required to start the clock (and to keep it running) was
      500 ppm C1O2 at all monitoring sites in the building, although the target concentration
      during fumigation was 750 ppm.

   3) Decontamination, in which the C1O2 concentration in the building would be maintained
      above the minimum value (and presumably above the target value) - and the RH and
      temperature maintained at or above the required values - for the duration necessary to
      achieve a total CT of at least 9,000 ppm-hr.
                                          124

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   4)  Neutralization, in which the C102 concentrations in the building would be reduced below
       the OSHA 8-hour Permissible Exposure Limit (PEL) of 0.1 ppm following fumigation.
       Neutralization of the C1O2 was achieved by replacing the aqueous C1O2 flows into the air
       strippers with sodium sulfite - converting the C1O2 emitters into scrubbers - and by
       continued exhausting of the building air through the sodium sulfite scrubbers and carbon
       beds associated with the negative air units.  Natural decay of the C1O2 also played a role.

Dehumidification is also implemented during the neutralization step, with RH being reduced to
avoid mold growth and other moisture-related problems.  Dehumidification to about 50% RH
was achieved by chilling the sodium sulfite solution being delivered to the emitters-turned-
scrubbers, so that these scrubbers would also serve as condensers.  Further dehumidification to
20% RH - to ensure drying of all interior surfaces over the following two days - was achieved
using silica  desiccant dehumidifiers.

Following a series of tests to verity the performance of the negative air units, the building
temperature and RH control system, the building air mixing, and the operability of the total
system at a low C1O2 concentration, EPA issued a crisis exemption for this C102 fumigation to
proceed. The four-step fumigation process was conducted beginning on October 24,2003.

Concentrations of C1O2 were measured using gas samples drawn on an hourly basis from each of
33 sampling locations distributed inside the building. Temperature and RH were monitored
continuously at these same 33 locations, and at some additional locations. In accordance with
the four-step process above, Hie CT clock for the fumigation was started at 7 pm on October 24,
and continued uninterrupted for 12 hours (until 7 am on October 25), at which time C1O2
generation was stopped. The total average CT exposure throughout the building during that 12-
hour period was about 19,300 ppm-hr (ranging between 15,500 and 21,800 ppm-hr at the various
monitoring  locations throughout the building), all well above the 9,000 ppm-hr target.

Throughout the Hamilton fumigation process, EPA's Environmental Response Team (ERT)
monitored the ambient air in the area around the HSOB using a mobile monitoring van, sampling
for C1O2 and C12. Measurements were also made at the fence-line, and on the building itself.
The ambient concentration never reached the level that would have required generator shut-
down.  The C1O2 concentration measured by the ERT remote from the building never exceeded
the background level of 3 parts per trillion, well below the level of concern.

As at the other anthrax fumigation sites, the success of the fumigation at Hamilton was
determined through: 1) surrogate spore strips throughout the building, to verify that fumigation
conditions had in fact been maintained adequately to kill surrogate spores; and 2) environmental
samples taken after fumigation, including both surface sampling and aggressive air sampling.
Slightly more than one percent of the 4,885 individual spore strips were positive for growth. As
a result, additional surface environmental samples were collected at locations where positive
spore strips had been found. All environmental samples were negative for anthrax.  Based on the
totality of results, the Environmental Compliance Committee concluded in February 2004 that
the remediation was successful, and recommended that the facility be re-opened.
                                          125

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5.1.5  Concerns for the User

Below is a summary of the Occupational Safety and Health Administration's guidelines for the
use and storage of C1O2.  This information was extracted from ihe following website:
http://wvv\v.osha.gov/SLTC/healthguideiines/chlorinedioxide/recognltion.html.

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit
(PEL) for chlorine dioxide is 0.1 ppm as an 8-hour time-weighted average (TWA) concentration
(29 CFR 1910.1000, Table Z-l). The National Institute for Occupational Safety and Health
(NIOSH) has established recommended exposure limits (RELs) for chlorine dioxide of 0.1 ppm
as a TWA for up to a 10-hour workday, and a short-term exposure limit (STEL) of 0.3 ppm. The
American Conference of Governmental Industrial Hygienists (ACGM) has assigned chlorine
dioxide threshold limit values (TLVs) of 0.1 ppm as a TWA for a normal 8-hour workday and a
40-hour workweek, and a short-term exposure limit (STEL) of 0.3 ppm for periods not to exceed
15 minutes.  Exposures at the STEL concentration should not be repeated more than four times a
day, and should be separated by intervals of at least 60 minutes.

Exposure  to chlorine dioxide can occur through inhalation, ingestion, and contact with the skin
or eyes. To limit or control exposure, the following preventative steps should be taken by the
user:  the area of use should be enclosed; local exhaust ventilation should be utilized; and
personal protective equipment should be worn. Chlorine dioxide should be stored in a cool, dry,
well-ventilated area in tightly sealed containers that are labeled in accordance with OSHA's
Hazard Communication Standard (29 CFR 1910.1200).  Containers of chlorine dioxide should
be protected from physical damage, ignition sources, and light, and should be stored separately
from carbon monoxide, dust, fluoroamines,  fluoride, hydrocarbons (e.g., butadiene, ethane,
ethylene, methane, propane), hydrogen, mercury, non-metals  (phosphorus, sulfur), phosphorus
pentachloride-chlorine mixture, platinum, potassium hydroxide, water, or steam. To avoid an
explosion hazard, chlorine dioxide should be stored only in diluted forms. Solutions of more
than a 10 percent concentration should not be handled.  Empty containers of chlorine dioxide
should be handled appropriately.

The guidelines provide exposure limits and safety considerations for the use of chlorine dioxide
for numerous applications. One might anticipate that, because the gas kills spores, it is also toxic
to humans. It is important to note that the concentrations reported as flammable or explosive are
orders of magnitude higher than those required for sterilization., and are not achieved in normal
operations.

5.1.6  Availability of the Technology for Commercial Applications

There are numerous commercial vendors for the supply of C102.  Table 5.1-2 presents data for
domestic and foreign manufacturers.  While the applications section reflects the information
from the company's website, it is fair to conclude that the chlorine dioxide generated by any of
these systems could conceivably be utilized for decontamination of bacterial spores in buildings
or enclosed spaces. However, some of these technologies have not been tested on a building
scale, and it is possible that practical  technical or economic considerations could impact the
applicability of some of these technologies to building applications.
                                          126

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5.1.7  Cost for generation

In an effort to obtain some cost data for the generation of gaseous C1O2, SAIC approached
several vendors in an attempt to get a cost estimate for a chlorine dioxide facility having a
capacity of 30,000 Ib C102/day. This would have been more than adequate to treat the Hamilton
P&DC, making reasonable assumptions regarding the C102 decay rate in the building and the
building exhaust rate. However, the vendors declined to provide costing information, saying that
more information would be required about the envisioned site to permit a meaningful estimate.

5.1.8  Advantages and Disadvantages

All gaseous bioremediation technologies require a gas that is, by definition, reactive.  As such,
the material is dangerous to living things.  Following are disadvantages for the use of C102 in
remediation.

   1.  The gas is unstable and must be constantly replaced to attain the target concentration for
              the required time.
   2.  The gas must be generated onsite, and the equipment required to do this can be
              significant.
   3.  The killing efficiency decreases significantly at relative humidity levels below 70
              percent.  Maintenance of humidity is critical.
   4.  A large volume of liquid waste materials is generated.
   5.  Some reports from field fumigations suggest that some collateral damage may occur to
              the surfaces of machinery and electrical systems, resulting from condensation.

The advantages of C1O2 include:

   1.  C1O2 is well documented as a disinfectant for spores, vegetative bacteria and viruses.
   2.  Rapid natural breakdown of C102 eases its removal after application.
   3.  The gas is very soluble and stable in water.
   4.  The gas is effective on porous and non-porous surfaces and reaches all regions within an
              enclosure except for the hardest to reach, isolated areas (e.g., closed employee
              lockers).
   5.  The gas can be commercially generated by several methods.
   6.  The gas leaves no residue.
   7.  The gas odor can be detected by humans at a concentration (0.1 ppm) equal to the PEL.

Regarding the potential problem of collateral damage, mentioned above, there have been
undocumented reports from some of the field remediation sites that electrical circuit breakers
needed to be replaced following C1O2 fumigation, potentially due to condensation of moisture
and aqueous C1O2 at the high-humidily conditions.  Post-fumigation inspections have indicated
some collateral damage to machinery, equipment, and materials. No  electrical shorts have been
observed during fumigation.  Collateral damage may be limited in part due to the quick
dehumidification of the buildings following fumigation.
                                           131

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EPA, 1999. "Chapter 4: Chlorine Dioxide," in Guidance Manual -Alternative Disinfectants and
Oxidants.  EPA-815-R-99-014.  U.S. Environmental Protection Agency, Office of Water,
Washington, D.C.

EPA, 1981. Treatment Techniques for Controlling Trihalomethanes in Drinking Water,
EPA/600/2-81-156. U.S. Environmental Protection Agency, Cincinnati, OH.

EPA, 1979. Effectiveness of Chlorine Dioxide as a Wastewater Disinfectant, in Progress in
Wastewater Disinfection Technology, EPA-600/9-79-018. U.S. Environmental Protection
Agency, Cincinnati, OH.

ERCO, 2004.  "Water Treatment with C1O2." Available at:
wmv.clo2.CQm''\\tupgrade/treatm8nt.htmi. Accessed November 2004.

Freymark and Rauh, 1978.  Freymark, S. G.; and Rauh, J. S. "Selective Oxidation of Industrial
Wastewater Contaminants by Chlorine Dioxide," Proceedings: Mid. Ail. Ind. Waste Conf., Vol.
10, page 120.

Kirk-Othmer,  1993. Encyclopedia of Chemical Technology, Fourth Edition, Volume 5,
"Chlorine Oxygen Acids and Salts (C1O2, HC102)." Pages 976-979.

Lillard, 1979.  Lillard, H. S. "Levels of Chlorine and Chlorine Dioxide of Equivalent
Bactericidal Effect in Poultry Processing Water," J. Food Sci., 44:1594 (1979).

Masschelein, 1980. Masschelein, W. J.  "The State of Art in the Use of Chlorine Dioxide and
Ozone in the Treatment of Water," Water SA, 6(3): 116-129 (1980).

McCarthy, 1945. McCarthy, J. A. "Chlorine Dioxide for the Treatment of Water Supplies," J.
NEWWA,59:252(1945).

Oliver et al., 1989. Oliver, S. P.; King, S. H.; Torre, P. M.; Shull, E. P.; Dowlen, H. H.; Lewis,
M. J.; and Sordillo, L. M. "Prevention of Bovine Mastitis by a Postmilking Teat Disinfectant
Containing Chlorous Acid and Chlorine Dioxide in a Soluble Polymer Gel," J. Dairy Sci., 72:
3091 (1989).             ;

Page et al., 1976. Page, T; Harris, R. H.; and Epstein, S. S. "Drinking Water and Cancer
Mortality in Louisiana," Science, 193: 55 (1976).

Princiotta, 2003. F. T. Princiotta and G. B. Martin, "Observations on Engineering Aspects of the
Brentwood Postal Facility Fumigation," presented at the First World Conference on Risk,
Brussels, Belgium, June 2003.

Rauh, 1979. Rauh, J. S. "Disinfection and Oxidation of Wastes by Chlorine Dioxide," J.
Environ. Sci., 22(2): 42 (1979).
                                          134

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Rav-Acha, 1984. Rav-Acha,C. "The Reactions of Chlorine Dioxide with Aquatic Organic
Materials and Their Health Effects," Water Res., 18( 11): 84 (1984).

Ridenour and Armbruster, 1949. Ridenour, G. M; and Armbruster, E. H. "Bactericidal Effects
of Chlorine Dioxide," J. Amer.  Water Works Assoc., 41: 537 (1949).

Roe, 1976. Roe, F. J. C.  "Preliminary Report of Long-Term Tests of Chloroform in Rats, Mice
and Dogs," unpublished Report. Cited in: Ozone, Chlorine Dioxide and Chloramines as
Alternatives to Chlorine for Disinfection of Drinking Water. Water Supply Research, U.S.
Environmental Protection Agency, Office of Research and Development, Cincinnati, OH.

Schaudies and Robinson,  2003. Schaudies, R. P.; and Robinson, D. A. "Analysis of Chlorine
Dioxide Remediation of Washington, DC, Bacillus anthracis Contamination," report to the U.S.
Environmental Protection Agency under Contract No. GS-23F-8006H, 2003.

Synan et al., 1975. Synan, J. F.; MacMahon,  J. D.; and Vincent, G. P.  "Chlorine Dioxide, A
Development in the Treatment of Potable Water," Water Wks. and Sew., 91: 566 (1975).

Thiessen et al., 1984. Thiessen, G. P.; Usbome, W. R; and Orr, H. L.  "The Efficacy of Chlorine
Dioxide in Controlling Salmondla Contamination and Its Effect  on Product Quality of Chicken
Broiler Carcasses," Poultry Sci., 63: 647 (1984).

West Dugway Test Center, 2002. "Abbreviated Test Report for the Validation of Chlorine
Dioxide Decontamination," Test Project No. 8-CO-210-000-084, WDTC Document No. WDTC-
TR-02-059. (Note: Contents of the cited report appearing in the current document are used by
permission. Requests for the entire document should be referred to the U.S. EPA, Region 8,
8EPR-ER, 999 18th Street, Suite 300, Denver, CO 80202.)
I
I
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52    Hydrogen Peroxide Vapor

The use of aqueous hydrogen peroxide as a decontaminant has a long history (see Section 3.3 of
this report). One of the earliest published records for use of aqueous H2O2 is from 1883, when
hydrogen peroxide was 'used as a bactericide to preserve milk (Schrodt, 1883).  A comprehensive
review of the early uses of aqueous hydrogen peroxide as a disinfectant was published in 1972
(von Bockleman and von Bockleman, 1972). In 1989, the U.S. Environmental Protection
Agency (EPA, 2004a) approved the use of vapor-phase hydrogen peroxide as a sterilization
process.

5.2.1  Description of the Technology Alternative

A number of hydrogen peroxide vapor generation systems are commercially available for small-
scale chamber sterilization of, for example, pharmaceutical  equipment. Several of these have
been adapted for potential use  in the fumigation of larger volumes, applicable to buildings.
                                    How VHP bsodeconiaminailon works.*..
In all cases, the hydrogen peroxide vapor is generated from a concentrated aqueous solution of
hydrogen peroxide (^30% H2O2).  The vapor may be generated by controlled heating of the
liquid, in a manner that reduces
decomposition of the H2O2. Other
methods, such as heated aerosolizers,
have been considered.  Like other
oxidizing fumigants, the peroxide
decays with time - at a rate even faster
than C1O2 - and it is thus necessary to
continuously supply fresh peroxide into
the space at a rate sufficient to maintain
the desired concentration.  As
discussed later, typical H2O2 vapor
concentrations (e.g., 200 pprn, or about
0.3 mg/L) might require perhaps 2 to 6  F-     g M  Chemka, Reactions to Generate and
hours of contact time to destroy anthrax Remow H „      Peroxide from ^ Air
spores  depending on the substrate. At  (Source: STERIS Corporation)
the end of the operational cycle, the
H2O2 generator is turned off, and hydrogen peroxide vapor is withdrawn from the space and
passed over a catalyst (complementing the natural decay) to  convert it into water and oxygen,
thus leaving no toxic residue (Lauderback et al., 2002).  Figure 5.2-1 shows a schematic of the process.

Relative humidity is an important parameter in determining the performance of hydrogen
peroxide vapor, although the optimal RH level varies with the specific'H2O2 process. The
STERIS process, discussed below, maintains a low humidity  in the space (below 40% RH at the
start of fumigation), in an effort to keep the peroxide in the vapor phase for improved penetration
of substrate surfaces.  By comparison, the BIOQUELL process permits higher RH values,
attempting to achieve "micro-condensation" of a thin film of peroxide over the surface to be
decontaminated.

5.2.2   Technical Maturity
                                          136

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Figure 5.2-2.  The BIOQUELL Clarus C
and Claris L Units for hydrogen peroxide
vapor generation.
                                          Hydrogen peroxide vapor is well documented in
                                          the literature as an effective sterilizer of viruses,
                                          fungi, bacteria, and spores in controlled
                                          laboratory environments (Block, 2001; Klapes
                                          and Vesley, 1990; Kokubo et al., 1998). It has
                                          been registered by EPA for use as an
                                          antimicrobial pesticide for sterilization of sealed
                                          enclosures such as isolators, workstations, and
                                          pass-through rooms in commercial, institutional,
                                          and industrial settings (EPA, 2004a).  The
                                          process is commercialized and hydrogen
                                          peroxide vapor generation systems are offered as
                                          turnkey operations. Hydrogen peroxide vapor is
generated from concentrated aqueous hydrogen peroxide solution (Lauderback et al., 2002).
Figures 5.2-2 and 5.2-3 show hydrogen peroxide vapor generation
systems that are commercially available from BIOQUELL and
STERIS.

The BIOQUELL Clarus C was designed for use in the pharmaceutical
industry for the sterilization of filling lines, isolators, and clean
rooms. This unit is being considered for adaptation to address
building fumigation applications. The smaller unit, Clarus L, is
designed for smaller applications such as incubators and equipment
sterilization.  The hydrogen peroxide product used in BIOQUELL's
Clarus C and Clarus L systems is not registered with EPA under
FIFRA.
                                                                Figure 5.2-3. The
                                                                STERIS VHP 1000
                                                                Vaporized Hydrogen
                                                                Peroxide system.
STERIS Corporation is another manufacturer of hydrogen peroxide
vapor equipment (referred to as Vaporized Hydrogen Peroxide®, or
VHP).  Their larger unit, the VHP 1000 (shown in Figure 5.2-3), has
been used for decontamination of chambers and enclosed areas for ten years and is applicable for
rooms up to 6,000 ft3 in size. The STERIS hydrogen peroxide product has been registered by
EPA under FIFRA. In more recent operations, multiple units were combined in a single
operation to remediate significantly larger rooms.  Scaled-up versions of the VHP 1000 have
recently been tested by STERIS, with multiple units being combined to treat volumes up to
200,000 ft3 in actual applications (SAIC, 2003). This represents a significant enhancement in
capability.

The STERIS Corporation was contracted to conduct fumigation of the two U.S. Government
mail facilities  that were contaminated with Bacillus anthracis spores via the mail system:  the
General Services Administration's Building 410 in Washington, D.C. and the US. State
Department Mail Facility in Sterling, Virginia, (Loudoun County, 2004).  The buildings were
sectioned into smaller areas (approximately 100,000 to 200,000 ft3 each) and fumigated with the
hydrogen peroxide vapor.  The experience at the State Department facility is discussed further in
Section 5.2.4 of this report.
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5.2.3   Applications for Hydrogen Peroxide Vapor

Hydrogen peroxide is a strong oxidizing agent with a wide variety of applications. As a dilute
aqueous solution (3 percent) it is sold for home use for disinfecting minor cuts and scrapes.
More concentrated (10 percent) solutions are used for home hair bleaching treatments.  See
Section 3.3.  The strong oxidizing potential of hydrogen peroxide is highlighted by the
incorporation of hydrogen peroxide in ecologically friendly rocket propellants (Lauderback et
al, 2002).

Aqueous hydrogen peroxide has been in use for over one hundred years for its ability to kill
bacteria (Schrodt, 1883).  Specific aqueous H2O2 products (including hydrogen peroxide and
peroxyacetic acid mixtures) have been registered for indoor use on hard surfaces (e.g., in food
establishments, medical facilities, and home bathrooms) since as early as 1977, and have been
granted crisis exemptions by EPA for used on hard surfaces for destruction of anthrax spores
(EPA, 2004b). Hydrogen peroxide in the vapor form is registered as a pesticide by EPA for use
in killing bacterial spores on environmental surfaces within enclosed areas in commercial,
institutional, and industrial settings (EPA, 2004a). More recently, H2O2 vapor has been granted
crisis exemptions for treatment of anthrax spores specifically in the fumigations of GSA
Building 410 and the State Department mail annex, mentioned above.

Vaporized hydrogen peroxide generators generally use a 35 percent aqueous hydrogen peroxide
solution (Lauderback et al., 2002). The aqueous hydrogen peroxide is vaporized at temperatures
of 70-140 °C.  In this vaporized form, hydrogen peroxide has been reported to inactivate
pathogenic bacteria, yeast, and bacterial spores. The rate of activity of peroxide is sharply
increased by heat, ultraviolet light, and ultrasonic energy.  There have been promising results
from experiments using peroxide vapor for space decontamination of rooms and biologic  safety
cabinets  (Kirk-Othmer, 1993).

Hydrogen peroxide vapor is registered as an antimicrobial pesticide for use in commercial,
institutional, and industrial settings, for the decontamination or sterilization of sealed enclosures
including scientific workstations, isolators, pass-through rooms, and medical and diagnostic
devices (EPA, 2004a).  Hydrogen peroxide  vapor decontamination technology has been used in
the pharmaceutical industry for over ten years. More than 700 hydrogen peroxide vapor systems
are used  in this industry worldwide, and they have proven to be effective against a variety of
microorganisms (STERIS, 2004).

Vaporized hydrogen peroxide is also used in plasma sterilizers.  These commercially available
sterilizers use hydrogen peroxide and a vacuum as in the standard hydrogen peroxide vapor
generators, but also use low pressure plasma.  The plasma induces free  radicals and ions,
enhancing the hydrogen peroxide vapor's effectiveness at killing microbes.  Experiments using
hydrogen peroxide vapor conducted  with and without plasma suggest that the addition of plasma
to the equation results in a better, faster decontamination (Sias, 2003).  This decontamination
technology is used for sterilizing surgical instruments. A patent exists for the use of peroxide
vapor and a  radio frequency energy generated plasma which releases free radicals, ions, excited
atoms, and excited molecules in a sterilizing chamber (U.S. Pat. 4,643,876,1987, P.T. Jacobs
and S.M. Lin) (Kirk-Othmer, 1993).  Yet another variation of hydrogen peroxide vapor
decontamination technology exists, Binary lonization Technology (BIT). BIT also uses
                             f
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hydrogen peroxide and plasma, but it does not require a vacuum environment or containment
within a chamber (Sias, 2003).
Although vaporized hydrogen peroxide and hydrogen peroxide plasma technologies have proven
to be effective decontamination methods, they did not have widespread acceptance as of 1996.
Historically, steam, ethylene oxide, and dry heat have been the preferred methods of sterilization
of biomedical devices (Kirk-Othmer, 1997).

5.2.4  Evaluation of Available Data

5.2.4.1 Data from laboratory testing

The efficacy of a chemical as a sporicide is.expressed in terms of log kills and D-Values. A one
log kill represents 90 percent killing efficiency. A six log kill, required for sterilization is a
99.9999 percent killing efficiency. A D-value is the contact time required for a one log kill. In a
1991 published report the D-values of liquid and hydrogen peroxide vapor were compared using
three different bacterial spore types.  As shown in Table 5.2-1, the concentration of hydrogen
peroxide in water is over 200-fold greater than the concentration required in the vapor-phase to
achieve similar microbial activity (Block, 2001).

       Table 5.2-1. Effectiveness of Hydrogen Peroxide Liquid and  Vapor on Spores
Test Organism
(spores)
B. stearothermophilus
B. subtilis
C sporogenes
D-value (tune to kill one log of test organism in minutes)
Liquid
HjO2 Concentration 370 mg/L
Terno 24-25 Celsius
1.5
2.0-7.3
0.8
Vapor
HjOj Concentration 1-2 mg/L
Temp 24-25 Celsius
1-2
0.5-1
0,5-1
STERIS Corporation provided the data shown in Figure 5.2-4.

The D-values (time required to kill 90 percent of the initial population) for a variety of bacterial
spores were determined with hydrogen peroxide vapor. Spore populations of 106 were deposited
onto 316 stainless steel coupons. The contaminated coupons were exposed to Vaporized
Hydrogen Peroxide at a concentration of 1,370 ppm at approximately 30-37 °C. The
thermophilic Geobacillus stearothermophilus, which is used on many commercial biological
indicators, exhibited the greatest resistance to the process as shown in Table 5.2-2.
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                                                 § §1  ?  ? iii
Figure 5.2^. Hydrogen Peroxide Vapor C,
oncentration versus D-value
Table 5.2-2. D-Values of bacterial
                                                                  P-oxide
                                                                       were



                                                 was less saturated with water
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vapor, the process was more effective at the higher temperatures due to the increased
concentration, as well as the faster reaction rates of hydrogen peroxide vapor reacting with the
target cell constituents.
      Table 5.2-3. Hydrogen peroxide vapor efficacy at various temperatures against
(jeobacillus stearomermophilus s
Temperature (°C)
4
25
37
55
Hydrogen Peroxide Vapor
Concentration (ppm)
350
700 - 1500
2000 - 3000
>7000
lores
Typical D- Value
8-12 minutes
1 - 2 minutes
30-60 seconds
One second
In pharmaceutical manufacturing, the performance of hydrogen peroxide vapor is routinely
monitored by the use of biological indicators (Bis). The Bis are either strips of polymeric non-
woven fabric or stainless steel coupons inoculated with spores of Geobacillus
stearothermophilus or other appropriate indicator microorganism. A successful decontamination
cycle is determined by complete inactivation (sterilization) of the biological indicator.
Geobacillus stear other mophilus spores have been identified as the most resistant organism to the
hydrogen peroxide vapor process (Rickloff and Orelski, 1989).

In response to the anthrax containing letters delivered to Florida, New York, and Washington,
D.C., the U.S. EPA in Denver Colorado contracted the West Desert Test Facility at Dugway
Proving Ground to test the effects -of C1O2 and hydrogen peroxide vapor on a variety of dried
Bacillus spores:

*      BAA - Bacillus anthracis var. cones,
•      BAV - Bacillus anthracis var. vollum,
•      BAS - Bacillus anthracis var. sterne,
•      BGN - Bacillus subtilis var. niger,
•      BT - Bacillus thuringiensis, and
•      BST - Bacillus stear other mophilus.

The C1O2 data from this testing were discussed in Section 5.4.1.1.  The data obtained from the
one trial with H2O2 vapor are discussed and illustrated below, excerpted from the study report
(West Dugway Test Center, 2002).

Spores from three strains of Bacillus anthracis (BA) and three BA simulants were applied as a
liquid slurry and dried on either glass cover slips (all six organisms) or porous filter paper (BAA
and BAV only), and were exposed to hydrogen peroxide vapor in a chamber under controlled
conditions for 12 hours. The Dugway team did not control for temperature; discussions with the
team indicated that they operated at ambient temperatures (70-75 °F).

During the course of the 12-hour run, triplicate slides were removed from the sterilization
chamber at specific time intervals, and cultured to determine presence of viable spores.
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Hydrogen peroxide vapor was used during Trial 6.  Hie vapor was generated using a STERIS
VHP 1000 unit in accordance with the manufacturer's instructions (STERIS, 1996), heating 30 to
35 percent aqueous H202 to form the vapor. The VHP 1000 unit operates on a four-phase cycle.
In the first phase - which occurred prior to the introduction of gas into the Dugway chamber -
the chamber was dehumidified utilizing a dehumidifier incorporated into the VHP 1000 unit.
Dehumidification is important in the VHP process, to reduce condensation of aqueous H2O2.
Dehumidification was followed by the second, conditioning phase fa this phase, the generator
introduced hydrogen peroxide vapor into the chamber at a rapid rate, to reach the desired
chamber operating concentration as  quickly as possible. After the desired concentration was
achieved, the VHP 1000 unit switched to the third, or fumigation, phase, reducing the hydrogen
peroxide vapor generation rate to the level required to maintain the desired concentration at
steady state for 12 hours. (This steady-state peroxide concentration was determined by the
vendor's settings on the VHP 1000 unit, and was not measured during this study.) The fourth and
last phase of operation was the aeration phase, in which the residual hydrogen peroxide vapor in
the chamber was removed so that the chamber could be opened without causing harm to
personnel.

The data obtained for this experiment is illustrated in Figure 5,2-5, as excerpted from the EPA
report. These results show that - at the potentially high gaseous H2O2 concentrations in the
chamber - all of the B. anthracis surrogates (BGN, BT, BST, and non-virulent B. anthracis v.
sterne) had been completely killed on the glass cover slips within 1 hour (a 6- to 8-log reduction
in spores). The virulent B.  anthracis v. ames strain (BAA) experienced a 6-log kill in 1 hour,
and complete (7-log) kill in 2 hours.  B. anthracis v. vollum (BAV) proved to be the most
resistant to H2O2 vapor, requiring 4 hours to sustain a 6-log kill, and 6 hours to experience total
(8-log) kill.

Hydrogen peroxide vapor does interact with many materials,  decaying in contact with the
surface, but it does not appear to be corrosive. Discoloration of dyes can occur and interactions
with nylon are not favorable. It has  been reported that nylon and other porous surfaces interact
with the hydrogen peroxide and degrade it, thereby making it inactive. In a personal
communication with STERIS representatives during the anthrax response in Washington, D.C.,
they reported that the gas was inactivated by celluloid compounds. This includes paper and
paper products.  In a more recent communication with Dr. Peter Burke of STERIS, he claimed to
have more recent data indicating less rapid decay of the vapor against porous surfaces (SAIC,
2003).

Research is underway through a work-in-kind cooperative research and development agreement
between Lawrence Livermore National Laboratory and STERIS Corporation to evaluate the use
of heating, ventilation, and air conditioning (HVAC) systems as a means to convey Hydrogen
peroxide vapor into building environments.  The experiments are evaluating the delivery of VHP
through the HVAC system, and quantifying the spore kill by culturing indicator strips (Carlson
and Raber, undated).
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                               Trial 6-Hydrogen Peroxide
Figure 5.2-5. Log of Colony Forming Units (cftis) Remaining at Each Time Point for Trial
6; Laboratory Validation of Hydrogen Peroxide Decontamination

NOTE:  BAA - Bacillus anthracis var. antes, BAV - Bacillus anthracis var. vollum, BAS - Bacillus anthracis var,
steme, BQN - Bacillus subtilis vat. niger, BT - Bacillus thuringiensis, BST - Bacillus stearothermophilus.
5.2.4.2 Experience with field fumigation of buildings

Experience at the U.S. Department of State Mail Annex (SA-32), Sterling, VA

This State Department mail processing facility (SA-32) in Sterling, VA, was contaminated with
B. anthracis spores in October 2001, possibly because the anthrax-containing letter addressed to
Senator Leahy may have been mis-directed to SA-32 prior to being returned to the Brentwood
P&DC (discussed in Section 5.1.4.2). SA-32 contains 1.4 million cubic feet of volume, making
it about one-quarter the size of the USPS Hamilton P&DC, and about one-tenth the size of the
Brentwood P&DC.

As with all of the buildings impacted by the 2001 anthrax mail attack, the initial step in the
remediation process for SA-32 was environmental sampling (swab sampling and vacuum sock
sampling) to characterize the extent of the contamination. Four such sampling events took place
in October and November 2001.
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With confirmation that the facility was contaminated, a significant effort was undertaken to seal
the building, to prevent release of the spores to the outdoor environment and, ultimately, to
prevent escape of the as-yet unselected fumigant All exterior doors (including loading dock
doors), windows, and vents were sealed with caulked polyethylene sheeting, and covered with
plywood to prevent puncture of the sheeting. The rooftop HVAC units that served the building
were all removed (after having been cleaned from inside the building), and the resulting
openings in the roof were sealed in the manner described above. All plumbing fixtures inside
the building were removed, and the water lines and plumbing vents capped.  Following
subsequent testing for leak-tightness, additional sealing was also performed, including caulking
around the joint where the exterior walls meet the roof.

In addition, five exhaust fans ("negative air machines", or NAMs) were installed on the building
- exhausting through HEP A filters, to capture any anthrax spores that could be in the exhaust -
to maintain the building under negative pressure throughout this entire process. This was
intended to prevent any spores inside the building from escaping into the ambient air.

Critical and salvageable items were decontaminated by several approaches for re-use.  Over
70,000 Ib of flat mail was treated by irradiation.  Bulk parcels were cleaned by HEPA
vacuuming, then tested for B. anthracis to verify  the effectiveness of treatment. Personal and
office items, including file cabinets and document storage units, were treated off-site using
ethylene oxide sterilization.  Over 46,000 diplomatic mail pouches were sterilized using
paraformaldehyde, using pre-constructed chambers set up in the SA-32 building for this purpose.

All interior finish and all postal equipment was removed from the building, reflecting the most
substantial source reduction effort of any of the remedial actions taken in response to the anthrax
mail attack. All interior frame walls, ceilings, carpeting, furnishings, etc., were removed, broken
down, treated with amended bleach (pH-adjusted sodium hypochlorite with acetic acid) or with
an aqueous hydrogen peroxide/peroxyacetic acid product (Spor-Klenz®), packaged, and sent for
destruction at a permitted medical waste facility.  Large metal items, such as the mail handling
equipment, were washed with soap and water, broken down, and placed in large containers,
which were shrink-wrapped in plastic. The exterior of the shink-wrap was cleaned with Spor-
Klenz, the containers were shipped for off-site ethylene oxide treatment, and the resulting
sterilized metal was recycled as scrap.

Following the removal of this interior finish and equipment, only the building shell remained -
the exterior walls  (and a few interior structural walls), the slab, the metal sheeting supporting the
flat built-up roof overhead, and the metal roof trusses, along with the electrical system. All of
these remaining interior surfaces were HEPA vacuumed, and washed with soap and water. In
sk areas known to have been contaminated by anthrax, based on the pre-remediation
environmental sampling, the surfaces were also wiped down with the amended bleach or Spor-
Klenz.

The  original intention had been to fumigate the entire facility with paraformaldehyde.  However,
following evaluation of alternative building remediation approaches, the State Department
selected gaseous H2O2 as the fumigant to be employed, using the STERIS Vaporized Hydrogen
Peroxide process.
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For the fumigation utilizing the STBRIS VHP gaseous H2O2 process, the cleaned and basically
empty 1,400,000 ft3 building was physically subdivided into zones using plastic sheeting.
Initially, there were seven zones, each approximately 200,000 ft3 in volume.  These zones would
be fumigated one at a time. The decision was made to subdivide the building, in part, in order to
reduce the H2O2 generation capacity that would have been required on-site were the entire
building volume to be fumigated at once. In addition, the VHP process had not previously been
used to treat volumes of this size, except at GSA Building 410, which also had been subdivided
into 200,000 ft3 zones. This subdivision into zones was achieved using polyethylene sheeting
that extended the entire width of the building, anchored to the floor slab, to the metal underside
of the roof, and to the front and rear walls.

The target fumigation conditions were that the vaporized H202 concentration in each zone would
have to be held at or above 0.3 mg/L (216 ppm) for 4 hours; the temperature would have to be
* 70 °F; and the "saturation level" would have to be <, 80%, to avoid condensation. The
saturation level is defined as the concentration of water vapor plus H2O2, expressed as a
percentage of the dew point concentration of these two compounds in combination at the
prevailing temperature.   It is noted that this peroxide concentration and exposure time (a total
CT of 860 ppm-hr) are much lower than the values specified for C1O2 fumigation, discussed in
Section 5.1.4.2 (750 ppm for 12 hr, or 9,000 ppm-hr), reflecting a higher reactivity of H2O2.

Sensor bundles were placed at six locations within each zone during its fumigation (with H2O2
monitors at two additional locations), to continuously monitor the concentrations of H-jO;, and
water vapor, and the temperature, to ensure that the target process conditions were achieved.
Among the buildings remediated following the 2001 anthrax mail attack, this was the only
fumigation in which real-time monitoring of fumigant concentration occurred. In addition,
chemical indicators (strips that changed color when exposed to a certain H2O2 CT) and biological
indicators (stainless steel spore strips containing 106 spores of an anthrax surrogate,  Geobacittus
stearothermophilus) were distributed throughout each zone, with approximately one of each type
of strip per 100 ft2 of zone floor area.  The chemical and biological indicators were co-located.
Fumigation of a given zone was judged to be complete when the target fumigation conditions
had be satisfied in that zone, when all chemical indicators had changed color, and when all
biological  indicators were negative for growth of the indicator spores when cultured following
fumigation.

The STERIS H2O2 generation system was installed outdoors, near one comer of the SA-32
facility. This system consisted of multiple (four to six) generators - each representing a
specially-designed adaptation of the VHP 1000 unit pictured in Figure 5.2-3 above - having a
total combined capacity initially deemed to be more than adequate to treat each of the seven
200,000 ft3 zones.  These generators produced gaseous HjOz by vaporizing an aqueous 35%
H2O2 feed solution.

In commercial practice, in the fumigation of small volumes, the VHP units automatically cycle
the treated volume through four phases. These four phases include: dehumidification, in which
the RH of the space is reduced to 40% or less; conditioning, in which the introduction of HjOj
vapor at high concentration is initiated, to bring the space up to the target fumigation
concentration as quickly as possible (while maintaining the saturation level at 80% or less);
decontamination, in which the space is maintained at or above the target concentration, at or

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above the target temperature, and below the target saturation for the specified time; and finally
aeration, in which the air within the space is cycled through a catalyst bed to destroy the residual
H2O2, reducing concentrations to a safe level.  (The H2O2 concentration considered Immediately
Dangerous to Life and Health is 75 ppm - less severe than the 5 ppm for C1O2 - and, commonly,
the objective is to reduce the concentration below 1 ppm, the OSHA Permissible Exposure
Limit, during the aeration phase.)

The specially-designed large-volume VHP system installed at SA-32 was configured to put the
200,000 ft3 zone through this same cycle. A blower near the generators recirculated the zone air.
The galvanized metal ductwork system associated with this blower was manifolded such that it
could withdraw air from, and supply air to, any one of the original seven zones, as controlled by
dampers within the ductwork. Air would be supplied to one end of the selected zone, and
withdrawn from the other end of that zone.  The modified VHP generators introduced vaporized
H202 into the supply side of this blower during the conditioning and decontamination phases for
the selected zone.

A regenerative desiccator was incorporated into this  recirculation loop. During the
dehumidification phase, zone air was circulated through this dryer without the VHP generators
operating, in order to reduce the relative humidity in the zone to 40% or less before conditioning
began. During conditioning and decontamination, the dessicator served to reduce the observed
increase in the zone's RH, helping prevent the zone's calculated saturation level from exceeding
80%.

The return air drawn out of the zone was  passed through a HEPA filter (to remove any spores or
dust) and a catalyst bed (to destroy the H202 in the extracted air stream) before entering the dryer
and blower. The residual H2O2 was destroyed during conditioning and decontamination to
facilitate control of the process.  During the aeration phase, recirculation of zone air through this
catalyst bed helped reduce concentrations below 1 ppm H2O2.

During the fumigation of each zone, at least 20 mixing fans were in operation within that zone,
in an effort to distribute the HjO;, uniformly throughout the zone.
While the fumigation of a given zone was underway, a 5,000 cfm exhaust fan drew air from all
of the zones not being fumigated, keeping the remainder of the building at negative pressure
relative to the fumigated zone and relative to outdoors.  The H2O2-containing exhaust from this
fan was passed through a catalyst bed, to reduce the H2O2 concentration to a very low level prior
to release to the atmosphere. The building was maintained under negative pressure to prevent
the H2O2 vapor from escaping through the building shell into the outdoor air.

The fumigation of the first of the seven zones was initiated in June 2003.  Difficulties were
encountered in achieving the desired 216 ppm H202 in the zone. It became apparent that a major
reason for this problem was that the vapor-phase H202 was reacting more rapidly than
anticipated with the limited remaining building surfaces inside the empty zone, and perhaps with
the galvanized metal supply ducting. The supply ducting was replaced with (or lined with) high-
density polyethylene, considered to be less reactive with H2O2.  Three of the 200,000 ft3 zones
(including the first) were eventually further subdivided into two zones, with the new sub-zone

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that was thus created ranging in size from 40,000 to 100,000 ft3. The total number of treated
zones was thus increased from seven to ten. For some fumigations, the number of VHP
generators was increased, to increase capacity where necessary to maintain the concentration
above 216 ppmat one or more of the continuous monitors.

During all fumigation activities, sensitive H2O2 sensors were located at various positions outside
the building, along the fence-line, and on some neighboring buildings. At no time did any of the
fence-line monitors detect ambient H2O2 concentrations above background.

In August 2003, the last of the zones was successfully fumigated according to the specified
process conditions: ^216 ppm H202 for 4 hours, i70 °F, saturation level ^80%. (Concentration,
temperature, and saturation typically varied within a zone during fumigation, but remained in the
specified ranges for 4 hours.) For all ten zones, chemical and biological indicator requirements
were also met. One zone had to be re-fumigated when one of the biological indicators showed
growth of the indicator organism, but all indicators tested negative after the second fumigation.

The difficulties that were encountered in maintaining the H202 concentration in some of the
zones during this fumigation underscore the need to more thoroughly understand the decay rate
of HjOz upon contact with various building surfaces, and to ensure that adequate generation
capacity is available to compensate for the H2O2 losses that will result.

Significant post-fumigation environmental monitoring was  conducted for B. anthracis, using
both surface sampling and aggressive air sampling techniques. The air sampling took place after
the interior surfaces of the zone to be sampled had been aggressively disturbed using a leaf
blower to re-suspend any residual spores.  All 619 samples cultured negative for B. anthracis.
On the basis that all environmental samples  were negative  for spore growth, and that the
fumigations had been successful in achieving both the target process conditions and the required
chemical and biological indicator results, the Environmental Clearance Committee concluded
that the remediation had been successful, and recommended in November 2003 that the facility
be re-opened. The Department of State subsequently renovated and refurbished the building,
incorporating a number of design and operational changes to better protect the workers  should
such an incident ever reoccur in the future.

5.2.5   Concerns for the User

Hydrogen peroxide vapor is  acutely toxic at high concentrations. The byproducts of tiie vapor
are harmless. The U.S. Occupational Safety and Health Administration (OSHA) has an eight-
hour Permissible Exposure Limit (PEL) for hydrogen peroxide gas of 1.0 ppm. The short-term
limit (Immediately Dangerous to Life or Health, or IDLH)  is 75 ppm for a 30-minute exposure.
One positive feature about this gas is that it is an irritant at levels above 1.0 ppm, minimizing the
inadvertent exposure to dangerous levels of the gas. The gas has a discemable, slightly pungent
or acidic odor at levels below the IDLH level, which adds to the safety factor.
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5.2.6  Availability of the Technology for Commercial Applications

There are multiple vendors offering commercial H2O2 vapor systems for sterilizing relatively
small volumes, such as sterilization chambers and pass-through rooms.  In addition, the
experience at the Department of State mail facility SA-32, and at GSA Building 410, has
demonstrated that it may be practical to adapt some of these commercial systems such that
volumes of 100,000 to 200,000 ft3 can be treated, perhaps by the use of multiple generators. A
key consideration in this scale-up is the need to understand how rapidly the highly reactive H2O2
vapor will decay in contact with typical building surfaces, so that the generation capacity can be
reliably estimated for cases where the building is not as thoroughly gutted as SA-32 was.

5.2.7  Advantages and Disadvantages

There are three main advantages to  this technology application. The first is that it has been
documented by many sources over a long period of time to be effective against viruses, bacteria,
and spores. The second is that the technology is currently available for implementation and
additional research. The third advantage is that the end products, after catalytic breakdown, are
water and oxygen.

One main disadvantages of this technology is that the vapor is reactive and can break down upon
contact with certain materials such as galvanized steel and porous surfaces such as paper and
unpainted cinderblock. The thought is that the high degree of surface area catalyzes the
conversion of the active gas to water and oxygen.  This is thought to be the cause of the
difficulties encountered at SA-32, described in Section 5.2.4.2  above.

5.2.8  Potential Areas for Future Research

The issue of surface inactivation should be addressed by testing the reactivity of hydrogen
peroxide vapor with different common building materials and office products, determining the
sterilization capability on  various surfaces found indoors. As with all scientific experimentation,'
independent verification of the results is recommended.

Scalability of the technology is another area for future research.  It is not clear if the limitations
of size are a function of the generation of the vapor or the stability of the vapor. Clearly,
multiple H2O2 generation units could be linked together to generate vapor in a large enclosure, as
was done in SA-32, with a separate  system to maintain negative air pressure of the larger
enclosure. The individual peroxide  generators would be designed to remove the vapor in their
respective locations during the "aeration phase" following fumigation.

Another key area for future research is the compatibility of H2O2 vapor with the materials found
inside buildings, in particular, with sensitive equipment.  This is an issue of concern for all
fumigants, not only hydrogen perioxide.
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5.2.9   References for Section 5.2

Block, 2001. Block, S. S.  "Peroxygeri compounds." In Disinfection, Sterilization and
Preservation, 5th ed. (S. S. Block, ed.), pp. 185-204. Lippincott Williams & Wilkins,
Philadelphia, PA, 2001.

Carlson and Raber, undated. Carlson, Tina; and Raber, Ellen "The Use of Vaporous Hydrogen
Peroxide for Building Decontamination." Unpublished report, For Official Use Only.  Lawrence
Livermore National Laboratory, Livermore, CA.

EPA,2004a, Pesticides: Topical and Chemical Fact Sheets - Vaporized Hydrogen Peroxide.
U.S. Environmental Protection Agency. Available at:
www.epa.gov/pesticides/factsheets/chemicals/vhp_factsheet.htm.  (Accessed December 2004).
                                             .                          i
EPA,  2004b. Pesticides: Topical and Chemical Fact Sheets - Hydrogen Peroxide and
Peroxyacetic Acid. US. Environmental Protection Agency. Available at:
www.epa.gov/pesticides/factsheets/chemicals/hvdrogenperoxide_peroxyaceticacid_factsheet.ht
m (Accessed December 2004).

Kirk-Othmer, 1993.  Encyclopedia of Chemical Technology, Fourth Edition, Volume 8,
"Disinfectants and Antiseptics."  Pages 255-256.

Kirk-Othmer, 1997.  Encyclopedia of Chemical Technology, Fourth Edition, Volume 22,
"Sterilization Techniques." Pages 832-851.

Klapes and Vesley, 1990.  Klapes, N. A.; and Vesley, D. "Vapor-phase Hydrogen  Peroxide as a
Surface Decontaminant and Stenlmt," Applied and Environmental Microbiology, 56(2): 503-
506 (1990).

Kokubo et ai, 1998. Kokubo,  M; Inoue, T.; and Akers, J.  "Resistance of Common
Environmental Spores of the Genus Bacillus to Hydrogen Peroxide Vapor." Journal of
Pharmaceutical Science and Technology, 52(5): 228-231 (1998).

Lauderback et aL, 2002. Lauderback, J.; Fraser, J.; Gustin, E.; McDonnell, G.; and Williams, K.
"Point-of-Manufacture Sterilization," Pharmaceutical and Medical Packaging News, October
2002.  Available at:  www.devicelink.com/pmpiVarchive/02/lQ/OQ5.html. (Accessed December
2004).

Loudoun County, Virginia, 2004.  U.S.  State Department Mail Facility Anthrax Cleanup: The
Latest News, www.co.loiidoun.Ya.us/general/cleanup.htm.  (Accessed December 2004).

Rickloff and Orelski, 1989. Rickloff, J.R.; and Orelski, P. A. "Resistance of Various
Microorganisms to Vaporized Hydrogen Peroxide in Prototype Tabletop Sterilizer," presented at
the 89th Annual Meeting of the American Society of Microbiologists, New Orleans, May 1989.

SAIC, 2003. Personal communication with Dr. Peter Burke, STERIS Corporation.

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Schrodt, 1883. Schrodt, M. "Bin neues Konservierungsittel fur Milch und Butter," Milch-Zig,
13: 785 (1883),

Sias, 2003.  Sias, Ralph. "Biological Organism Reduction with Hydrogen Peroxide," Advancing
Applications in Contamination Control, January 2003. Available at:
www.a2c2.coin/articles/Ufeian02.asp?pid:"328&articleText::::lifejan02.  (Accessed December
2004).

STERIS, 1996. Cycle Development Guide for VHP™ 1000 Biodecontamination System, pp.
129372-711.  STERIS Corporation, Mentor, OH. February 23, 1996.

STERIS, 2004. "Vaporized Hydrogen Peroxide Decontamination Systems." STERIS Corp.,
Mentor, OH.  Available at: www.steris.com/defense_mdustrial/pro_vhp.cfia (Accessed
December 2004).

Von Bockleman and von Bockleman, 1972. von Bockelman, I.; and von Bockleman, B.- "The
Sporicidal Action of Hydrogen Peroxide, A Literature Review," Lebensmittel-Wissenschott
Technologies, 5: 22 (1972).

West Dugway Test Center, 2002. "Abbreviated Test Report for the Validation of Chlorine
Dioxide Decontamination," Test Project No. 8-CO-210-000-084, WDTC Document No: WDTC-
TR-02-059.  (Note: Contents of the cited report appearing in the current document are used by
permission. Requests for the entire document should be referred to the U.S. EPA, Region 8,
8EPR-ER, 99918* Street, Suite 300, Denver, CO 80202.)
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5.3    Paraformaldehyde

Paraformaldehyde is a polymerized form of formaldehyde, (CHjO)^ It is a stable white
crystalline powder. Upon heating, it generates formaldehyde gas, which has antimicrobial
properties.  The antimicrobial properties of formaldehyde are believed to result from its
reactivity in the alkylation of proteins, nucleic acids, and DNA and RNA (Wickramanayake,
1990). Because pure formaldehyde is unstable at ambient temperatures (resulting in
polymerization), and is not commercially available (Kirk-Othmer, 1994), paraformaldehyde is a
material which can provide a readily-usable form of formaldehyde at use sites. Both
paraformaldehyde and formaldehyde have been used in decontamination for more than 30 years,
although the extent of this use (e.g., annual use quantities) is largely unknown.

5.3.1   Description of the Technology Alternative

Paraformaldehyde is used to generate formaldehyde gas for the decontamination of rooms,
storage cabinets, and equipment. A typical procedure for the use of paraformaldeyde is to isolate
the material or area being sterilized (e.g., sealing with tape or sheeting), using hot plates to
sublimate the paraformaldehyde and fans to distribute the vapor within the space for a specified
time period, and finally to introduce a compound that will neutralize the formaldehyde vapor
once treatment is complete (Munro et al, 1999).  The standard method for neutralizing the
formaldehyde is the use of ammonia generated by the heating of ammonium bicarbonate.

Alternatively, a more sophisticated approach - particularly applicable when treating larger
volumes - is to use a formaldehyde generator. In a generator, the heating of the
paraformaldehyde takes place inside a closed system, and the resulting formaldehyde is
introduced into the room to be treated (Certek, 1980).  One vendor of such generators is Certek
Inc.

Following removal of formaldehyde gas, some studies report that surfaces  are cleaned with
water to remove any remaining residue.  In particular, high humidity or high concentrations can
result in either the precipitation of paraformaldehyde or the condensation of formaldehyde in
water. Condensed formaldehyde/water mixtures would likely result in paraformaldehyde
deposits on the surfaces after the water evaporated (Hoffman and Spiner, 1990).

In addition to paraformaldehyde, formalin has also historically been used as a source of airborne
formaldehyde for sanitizing or decontamination purposes. Formalin is a 37 percent aqueous
solution of formaldehyde, stabilized by small quantities of methanol. Formalin is dispersed into
the air such as through a fogging apparatus (Wickramanayake, 1990). Because both
paraformaldehyde and formalin generate formaldehyde as the active ingredient, this chapter
addresses both the use of formalin fog and the use of paraformaldehyde to generate
formaldehyde gas for building decontamination, but with emphasis on the latter methodology.
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                                                            U.S EPA Headquarters Library
                                                                   Mail code 3404T
                                                            1200 Pennsylvania Avenue NW
                                                                Washington, DC 20460
 53.2  Technical Maturity                                          202-566-0556

 Paraformaldehyde vaporization is fully mature and has been routinely used worldwide for
 sanitizing and disinfecting rooms and equipment in the health services industry (Coldiron and
, Janssen, 1984) and in U.S. Army Medical Research Institute of Infectious Diseases
 (USAMRIID) biological laboratories (Alexander, 1998).  It was also used to decontaminate two
 pieces of postal equipment, which had been enclosed within a fumigation tent, in the Department
 of Justice mail facility in Landover, MD, which had become contaminated with B. anthracis
 spores in connection with the October 2001 anthrax mail incident.

 Paraformaldehyde technology has been applied to rooms and small spaces (such as laboratories
 and safety cabinets), and to individual equipment items enclosed in chambers or tents. However,
 it has been used in at least one building decontamination project.  The fumigant was used to
 destroy Ebola virus throughout the Hazelton Research Center in Reston, Virginia.  A
 concentration of 12,000 mg/m3 paraformaldehyde was used for the building. The size of this
 building was not given, but - based on the back-calculation from other available data - it was
 estimated to be 78,000 ft3 (2,200 m3) (Alexander, 1998).

 53.3  Applications of the Technology

 Paraformaldehyde (a solid) is used as a source of either gaseous formaldehyde or solution
 (aqueous) formaldehyde. When the crystalline paraformaldehyde powder is heated, it releases
 formaldehyde gas. When dissolved in water, paraformaldehyde behaves like aqueous methanol-
 free formaldehyde.

 Both paraformaldehyde and formaldehyde are primarily used in resin manufacturing, for uses
 such as adhesives and binders in consumer and industrial applications. Paraformaldehyde is
 used by resin manufacturers seeking low water content or enhanced reaction rate control, and in
 the production of phenol-, urea-, resorcinpl-, and melamine-formaldehyde resins (Kirk-Othmer,
 1994). Paraformaldehyde is also used in dentistry as a fixative. In these applications, the
 paraformaldehyde is dissolved in a solution to prepare aqueous formaldehyde.

 Paraformaldehyde was registered by EPA under FIFRA as a sanitizer and  fungicide for use on
 barber and beauty shop equipment in 1964. Since then, it has been registered and used as a
 disinfectant, sanitizer, fungicide, and microbicide in household and domestic dwellings, in ships
 and ship holds, on bedding and clothing, and in non-food/non-feed-transporting trucks (EPA,
 2004). It is unclear which of these applications use aqueous formaldehyde and which use
 gaseous formaldehyde.

 Under FIFRA definitions, a "sanitizer" is defined as a substance that significantly reduces
 bacterial populations, but does not destroy all bacteria or other microorganisms. A
 "disinfectant" destroys a specific species of microorganism- in particular, infectious (viral)
 microorganisms - but not necessarily bacterial spores. A "sterilant" destroys all forms of
 microorganisms, including all vegetative bacteria, bacterial spores, fungi, fungal spores, and
 viruses.  Paraformaldehyde has never been registered as a sterilant, although it has been
 demonstrated to be effective in killing B. anthracis spores under certain prescribed conditions.

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Paraformaldehyde has been used as a fumigant for more than 30 years.  It has been used to
decontaminate laboratory facilities and to disinfect sickrooms, clothing, linen, and sickroom
utensils (EPA, 2004). In these applications, paraformaldehyde is heated to form gaseous
formaldehyde.

Paraformaldehyde was registered and used to control microbial growth in laboratories and to
decontaminate animal facilities until recently, when all registrations for this use of the chemical
were canceled due to nonpayment of fees by the manufacturer (the name of the manufacturer
was not identified in the source). Quarantine use of paraformaldehyde has been allowed in a
poultry health laboratory in Arkansas (a use which was in effect through June 15, 2004).
Similarly, the Department of Defense was authorized to utilize paraformaldehyde for quarantine
use since 1993 (effective until July 6, 2002).  Similar exemptions for the use of
paraformaldehyde to decontaminate high-containment microbiological laboratories at Plum
Island, NY, and Ames, IA (effective until June 15, 2001) have also been granted to the USDA
(EPA, 2004).

A related use of gaseous formaldehyde is in low temperature steam formaldehyde (LTSF)
technology, a technique for decontamination of small items developed in the late 1960s.  In this
method, small non-disposable items are placed inside an apparatus which uses sub-atmospheric
(i.e., relatively low temperature) steam and gaseous formaldehyde. Typical conditions include
temperatures of 73 °C and formaldehyde levels of 8,000 mg/m3 (Hoxey et al., 1985). These
temperatures are impractical for larger scale (e.g., room) decontamination.

5.3.4   Evaluation of Available Data

More than 30 years of performance data regarding paraformaldehyde decontamination are
available, most in small-scale applications in clinical or research settings. This is likely to be a
reflection of its long use in the medical services industry for decontamination of biological
safety cabinets, laboratories, and reusable equipment.

While much of the testing and application of paraformaldehyde has focused on microorganisms
other than (or in addition to) bacterial spores, some of this testing has utilized bacterial spore
strips as a convenient means for assessing the antimicrobial impacts of fumigant. Among the
spores utilized in this spore strip testing are B. stear other mophilus, B. subtilis, and B. globigii (B.
subtilis v. niger).

In one study addressing spores directly, aqueous formaldehyde was used in the treatment of soil
contaminated with B. anthracis (Manchee et al., 1994). No data were reported from this study
relevant to the use of gaseous formaldehyde against this organism.

Coldiron and Janssen (1984) describe an example of paraformaldehyde use in decontaminating a
hospital autopsy suite at the University of Texas. This area consisted of three rooms, 73 meters
of connecting exhaust ductwork, and three exhaust air incinerators.  Concerns were for various,
unidentified microorganisms present throughout the suite, as a result of prior use, which would
pose potential risks to construction personnel.  Commercially available indicator strips of B.
stear other mophilus  and B. globigii were used to determine disinfection completeness. Based on

                                           153

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'no growth' results of the test strips placed throughout the room, successful decontamination
resulted from the use of 10.6 to 17.7 g/m3 paraformaldehyde, 3 to 4 hours of contact time, and
relative humidity of 65 percent (Coldiron and Janssen, 1984).

Munro et al. (1999) conducted tests to determine optimum decontamination conditions for metal
biological safety cabinets using paraformaldehyde.  Organisms tested included polio virus,
Mycobacterium bovis bacillus Calmette-Guerin (BCG), B. stear other mophilus, and B. subttlis.
All testing was conducted on stainless-steel coupons placed at various locations inside a metal
cabinet.  Optimal decontamination conditions were identified as 66 percent relative humidity, a
minimum temperature of 28 °C, and a paraformaldehyde concentration of 10.5 grams/cubic
meter. Figures 5.3-1 to 5.3-3 display the results of these studies, with independent variables of
concentration, relative humidity, and temperature, respectively (a 15 hour decontamination time
was used for all studies). The dependent variable in each case (percent survival) was measured
as the ratio of growth on the treated coupons versus growth on untreated controls (Munro et al.,
1999). Growth was measured in terms of 50 percent tissue culture infected dose (TCID50) for
polio, and colony-forming units (CPU) for other organisms. Figures 5.3-1 and 5.3-2 show that
the effectiveness of decontamination increased with concentration and humidity, while effects of
temperature resulted in marginal variability based on Figure 5.3-3. Table 5.3-1 shows the
survival of organisms as a function of location in  the cabinet. The authors conclude that B.
stear other mophilus was killed more readily than  B. subtilis, although completely successful
decontamination (total kill) was demonstrated for 7 of 144 coupons containing B. subtilis.
    Figure 5.3-1. Percent Survival of Test Organisms after Decontamination with
    Various Concentrations of Formaldehyde.
    Survival was measured as a percentage of the growth (CPU or TCIDSO) of that for the untreated control for
    each test organism. The data were for test pieces placed inside the cabinet on the side wall. (The relative
    humidity was <58 percent, and the temperature was <27 °C.) (Munro et al., 1999)
                                            154

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Figure 5.3-2. Percent Survival of Test Organisms after Decontamination at Various
Relative Humidities.
Paraformaldehyde weights were 25 g/m3, and the temperature was approximately 25 °C. (Munro et al.,
1999)
 Figure 5.3-3.  Percent Survival of Test Organisms with Variation of Temperature
 During Decontamination with Paraformaldehyde at £10.5 G/m3 and a Relative
 Humidity of Approximately 58 Percent. (Munro et al., 1999)
                                      155

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  Table 5.3-1.  Survival of Test Organisms on Strips Positioned at Different Test Locations
                                During Decontamination *
Location of strip
Under the cabinet
tray
Cabinet tray
Cabinet side
Beyond the exhaust
filters
Initial inoculation
level
B. subtilis
rCFU)
15,000
20,000
21,000
19,000
1.76x10"
B. stearothermophilus (CVU)
47.4
46
73.8
293.2
4xl05
BCG
(CPU)
<10
<10
<10
<10
1.39x10"
Polio virus (TCIDso/0-2
ml)
0
0
0
10o.«
10'"
a. Data are averages of three determinations. Decontamination conditions were as follows: parafor-
maldehyde, 10.6 g/m3; relative humidity, 57%; temperature, 28 °C; time, 15 hours. (Munro et al., 1999).
.Table 5.3-2 provides additional data summarized by G.B. Wickramanayake (1990).  The
 formaldehyde concentrations and decontamination time for testing are much lower than used by
 Munro et al. above, but nevertheless show inactivation to some degree.  In particular, Table 5,3-
 2 shows 6-log inactivation of B. subtilis which is apparently higher than the results by Munro et
 al, (1999), despite the higher concentrations and increased decontamination times used by
 Munro.

 Table 5.3-3 presents data by V.H. Lach (1990), which provides results of five different
 procedures in decontaminating a 38 m3 test room, using either formalin or paraformaldehyde as a
 source of formaldehyde.  Part of the purpose of this work was to attempt to reproduce conditions
 of previous studies, such as Taylor (1969), discussed below.  Therefore, comparisons of results
 between these studies are useful in assessing reproducibility. Unfortunately, the author noted
 that the low kill rate observed for the paraformaldehyde test in Table 5.3-3 was due to
 difficulties in simulating the conditions and formaldehyde release rate between the two tests.

 Based on the results by Lach, the author notes that the theoretical airborne concentration of
 formaldehyde (i.e., based strictly on quantity introduced divided by room volume) was always
 significantly greater than the measured concentrations. A possible explanation for this includes
 the condensation of water and formaldehyde, in which case the  use of lower quantities of
 formaldehyde could result in the elimination of condensed quantities. If this were true, a lower
 formaldehyde feed rate could have an effectiveness equivalent to a higher feed rate, if the losses
 due to condensation are eliminated at the lower rate. Such a hypothesis would require testing

 Many variations in decontamination as a function of bacteria or toxin placement were tested  at
 Fort Detrick, Maryland (Taylor et al., 1969). The results of these tests are shown in Table 5.3-4.
 As shown, materials tested included laboratory equipment and various surfaces, while the size of
 the facilities also varied from small to large rooms. For experiments involving rooms, test strips
 containing the organism were typically placed at various locations inside the room.
                                           156

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Table 5.3-2. The Effects of Formaldehyde on Various Organisms
Organism
Matrix
Formaldehyde
Concentration
Temp.
CC)
Relative
Humidity
(%)
Time
Inacti-
vafion
Source
Bacteria
E. coli
E. coli
B. globigu
B. subtilis
Dried on
steel rings
Dried on
steel rings
Dried on
steel rings
Not
identified
20 mg/mj
180mg/m3
20 mg/m*
300 mg/m3
20 to 27
20 to 27
20 to 27
20
SO
80
80
100
lOmin
<3
min
120
min
l.Shr
90%
90%
90%
99.9999%
(1)
(1)
(1)
(2)
Fungi
A. sydowi
A. flaws
A. Candidas
Scopuloriopsis
brevicaulis
Paecilomyces
varioti
A. sydowi
A. repens
A. chevalieri
A. versicolor
Dried
spores
Dried
spores
Dried
spores
Dried
spores
Dried
spores
In dust
samples
In dust
samples
In dust
samples
In dust
samples
2.5 mg/m3
2.5 mg/m3
2.5 mg/m3
2.5 mg/m'
2.5 mg/m3
2.5 mg/mj
2.5 mg/m3
2.5 mg/m3
2.5 mg/m3
20 to 22
20 to 22
20 to 22
20 to 22
20 to 22
20 to 22
20 to 22
20 to 22
20 to 22
65
65
65
65
65
65
65
65
65
24 hr
24 hr
24 hr
24 hr
24 hr
24 hr
24 hr
24 hr
24 hr
99.99%
99.99%
99.99%
99.99%
99.99%
•^
17%
96%
82%
50%
(3)
(3)
(3)
(3)
(3)
(3)
(3)
(3)
(3)
Source: Tables 4 and 6 of Wickramanayake (1990). The Wickramanayake article summarizes data
previously published k the following sources, which were not reviewed for the present report): (1)
Bovallius and Anas,1977; (2) Caputo and OdJaug, 1983; and (3) Klein and Deforrest, 1983.
                                        157

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     Table 5.3-3. Measured Average Conditions and Experimental Kill of B, Globigii
Formaldehyde
Source
Formalin
Formalin
Paraformaldehyde
Formalin
Formalin
Time
99
45 to 74
35 to 42
91 to >99
84 to >99
Kill (Joglc cycles)
>9 (all five locations)
5to>9
4 to 5 '.
6to>9
>9 (all five locations)
Source: Lach, 1990. In each test, five sensors were placed throughout a 38m3 test room. The above results
display the ranges of the average measurements. Organism levels varied from 102 to 3 x 10s. For all room
locations in each experiment, temperature varied over a narrow range of 23.2 to 25.8 °C.
a. Low kill rates due to difficulties in replicating target conditions.
For experiments involving pieces of equipment or smaller surfaces, the organism was typically
dispersed in air and allowed to settle, with subsequent testing performed by swabs or similar
means. Hie last column of Table 5.3-4 assists in identifying the procedures used.  In all cases,
the authors note that "the microorganisms were killed and the toxin was detoxified." However,
while initial levels of the microorganisms were presented (most tests ranged from 104 to 107
spores per mL), numerical results regarding the remaining spores were not available and
therefore log-kill data cannot be determined.

Tables 5.3-5 to 5.3-7 show experimental test data of the survival of B. subtilis versus variables of
time and relative humidity for three different types of stopper closures. These closures are
intended to investigate the ease with which formaldehyde can penetrate different materials.  The
spores were present inside the test tubes. The study, conducted by Hoffman and Spiner (1970) at
Fort Detrick, Maryland, provides insight into the penetrating ability of formaldehyde through
these materials, rather than the ability of formaldehyde to treat organisms embedded onto these
materials.  Some conclusions from the authors and from the presented data include the
following:

       •       Higher levels of formaldehyde (10.6 g/m3 versus 3.5 g/m3) result in faster bacteria
              kill, and higher exposure times result in higher levels of kill.  These results are
              somewhat obvious and expected.

       •       At a formaldehyde concentration of 3.5 g/m3, intermediate relative humidities
              (i.e., 33 to 75 percent) are best for penetrating paper, while very high humidity
              (i.e., 100 percent) is best for glassine penetration and very low humidity (11
              percent) is best for cotton penetration.  Similar conclusions were found for
              formaldehyde levels of 10.6 g/m3, with the exception that there was no significant
              difference in paper penetration for relative humidity between 33 and 100 percent.
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Table 5.3-4. Paraformaldehyde Sterilization of Facilities, Materials, and Equipment
Organism

B. subtills
Serratia
marcescens
B. subtitts
S.
marcescens
B. subtilis

B. subtilis

B. subtilis

B. subtilis


B. subtilis
S.
marcescens
B. subtilis
Newcastle
disease
virus
Newcastle
disease
virus
C.
botulinum
toxin type A
Description
of Facility
Tested

Laboratory
room

Laboratory
room

Mobile
laboratory
trailer
Two large
connected
rooms, of 4 to
5 stories each
15 types of
surfaces *

Within filter
media of a
class I storage
cabinet
Vaccine tubes
Vaccine tubes
Miscellaneous
electronic
laboratory
equipment
Interior
surface of test
chamber
Class I storage
cabinet

Air sampler
equipment
Facility
Volume
(m')

64

130

62

1,904

in 0.71 m}
chamber

in 1.3 m3
cabinet

in 0.06 m3
chamber
in 0.06 m3
chamber
2.8 to 14
0.03
1.2

in 0.08 mj
chamber
Parafor-
maldehyde
Cone.
fetor1)

10.7

10.7

5.4

8.6

10.7

10.7


10.7
10.7
10.7
10.7
10.7

10.7
Temp.
(•C)

23.3

23.3

23.3

31

24

24


Not
given
Not
given
-24
24
24

24
Relative
Humidity
(%)

60

60

60

50 to 55

60

60


60
60
>50
60
60

70 to 80
Contact
Time
(hours)

1

1

1

2

Ito2

1


1
1
Ito2
1
0.5

2
# Organism
Locations in
Test; Viable
Recoveries/
Total Tests
Conducted
15; 0/5
15; 0/5

15; 0/5
15; 0/5

20; 0/5

200; 0/1

(dispersed on
each
surface); 0/5
24; 0/5


(dispersed on
surfaces); 0/2
(dispersed on
surfaces); 0/2
(dispersed on
surfaces);
0/10
(dispersed on
surface) 0/1
6; 0/1

(dispersed on
surfacesX 0/3
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Organism
C,
botttlinum
toxin type A
C.
botulinum
toxin type A
Description
of Facility
Tested
Powder
samples (10
mg)
Powder
samples (20
nig)
FaciUty
Volume
(m3)
in 0.03 m'
chamber
in 0.03 m3
chamber
Parafor-
maldehyde
Cone.
(g/m*)
10.7
7.1
Temp.
CC)
23
24
Relative
Humidity
(%)
60
45
Contact
Time
(hours)
4
48
# Organism
Locations in
Test; Viable
Recoveries/
Total Tests
Conducted
I; 0/3
1;0/1
Source: Taylor et al., (1969).
a. The surface types tested were glass, rubber, plastic, stainless steel, galvanized metal, wood, paper, sponge,
filter paper, painted surface, rigid plastic, copper, aluminum, vinyl sheeting, and mild steel.
Table 5.3-5. Percent Recovery of B. subtitis in Test Tubes with Paper Closures
Exposure Time 
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Table 5.3-6. Percent Recover
Exposure Time (hr)
1
2
3
4
7
17
RH=11%
80.8
46.3
27.1
3.2
0.018
0.0016
v ofB. subtilis in Test Tubes with Glassine Closures
RH=33%
74.2
64.2
61.3
24.1
4.9
0.005
RH=53%
100
77.5
85.2
35.5
30.3
2.3
RH=75%
99.0
64.7
34.6
40.3
2.9
0
RH=100%
72.8
27.7
6.6
2.0
0.0005
0
Source: Hoffman and Spiner, 1970. Spores were present in test tubes with indicated closure; test tubes were
enclosed in a small testing chamber with 3.5 g/m3 formaldehyde gas generated from paraformaldehyde at
25 °C.
    Table 5.3-7. Percent Recovery of & subtilis in Test Tubes with Cotton Plug Closures
Exposure Time (hr)
1
2
3
4
7
17
RH=11%
62.9
20.4
7.0
0.6
0.0056
0.0003
RH=33%
71.6
41.2
27.6
11.0
0.061
0
RH=S3%
96.5
57.3
43.6
57.6
9.1
0
RH=75%
82.9
76.3
48.9
47.7
9.8
0
RH=1DO%
99.1
97.5
100
85.0
30.8
0.022
Source: Hoffman and Spiner, 1970. Spores were present in test tubes with indicated closure; test tubes were
enclosed in a small testing chamber with 3.5 g/m' formaldehyde gas generated from paraformaldehyde at
25 °C.
The differences in results by Hoffman and Spiner (1970) regarding penetration ability are likely
to cause difficulty in applications of building decontamination. Of the large variety of materials
potentially present in such a situation, these results indicate that there is no single 'ideal'
condition in treating them. The different materials present alternately may be best treated at
either low, moderate, or high relative humidity. On the other hand, for general ambient room
decontamination results from authors such as Coldiron and Janssen (1984) and Munro et al.
(1999), there is agreement that an intermediate relative humidity (e.g., 60 to 70 percent) is
effective. In attempting to apply these various results to building decontamination, consideration
could be made to the application of a variety of humidity conditions.  For example, humidity
could be maintained at one level for a period of time followed by a period of time with different
humidity.

Reflecting the experience with fumigations utilizing paraformaldehyde, several organizations
have issued procedures, guidelines, and regulations pertaining to its use for the treatment of
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various enclosed spaces (NIH, 1979), containment areas (USAMRIID, 1999), and biosafety
cabinetry (NSF, 2002).
Experience at the Department of Justice mail facility

The mail processing facility within the Department of Justice's Landover Operations Center
(LOG) in Landover, MD, became contaminated with B. anthracis spores during the October
2001 anthrax mail incident, probably through the processing of cross-contaminated mail.  The
contamination was discovered through precautionary environmental surface sampling that was
undertaken after the contamination at the USPS Brentwood P&DC was detected.  This sampling
indicated that the B. anthracis contamination was limited to the mail facility portion of the LOG,
and had not spread to other portions of the LOG warehouse.

Accordingly, the mail facility was isolated from the remainder of the warehouse using barriers
consisting of plywood and polyethylene sheeting.  The mail facility was exhaust ventilated using
three exhaust fans exhausting through a HEPA filter, to keep the mail facility under negative
pressure relative to the remainder of the LOG, and to thus prevent the spores from spreading to
other parts of the building.

For source reduction, essential items (e.g., certified mail receipts) were packaged and shipped
off-site for ethylene. oxide fumigation and re-use.  Non-essential porous items were cleaned to
the extent possible - usually with 0.5% bleach solution or HEPA vacuuming - packaged, and
shipped off-site for disposal.  Items that were thus removed and sent for disposal included
carpeting, upholstered furniture, non-essential paper, personal effects, and workstation cubicles.
                    \

Most non-porous surfaces were sprayed with aqueous chlorine dioxide solution or a surfactant
solution, and wiped down following a 30-minute contact period.  These surfaces included the
floor, walls, counters, shelves, and non-porous furniture (desks and file cabinets).  Non-porous
ceilings and HVAC ductwork were not cleaned.

Paraformaldehyde fumigation was used to treat two pieces of postal equipment, the mail sorter
and the stamping machine.  Fumigation was selected for this equipment because they contained
intricate components and difficult-to-reach areas that would have been impossible to
decontaminate using a liquid, except by disassembling the machine. The two pieces of
equipment were enclosed within a single tent (approximate volume 8,300 ft3) inside the mail
room, constructed using 2- by 4-inch wood framing and a double layer of 6-mil polyethylene
sheeting. EPA issued a crisis exemption under FIFRA to allow paraformaldehyde  to be used in
this application.

Multiple pans containing Hoechst-Celanese paraformaldehyde (95% pure) were placed on hot
plates inside the tent.  An excess of paraformaldehyde - beyond the minimum 0.3 g of
paraformaldehyde per cubic foot of tent volume (NIH, 1979; USAMRIID,  1999; NSF, 2002) -
was placed on the hot plates such that the formaldehyde concentration inside the tent would be
maintained at the required level (about 8,900 ppm) for the  required 12-hour exposure period.  An
airless sprayer released a water mist into the tent as required to maintain the RH above 50%.

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When each stage of the fumigation was over, hot plates inside the tent were activated that
contained ammonium bicarbonate (1.5 g of ammonium bicarbonate per gram of paraform-
aidehyde).  After the vaporized NH4HC03 neutralized the formaldehyde inside the tent, the tent
was vented to the outdoor air.

The 12-hour fumigation process consisted of two 6-hour treatments. After the first 6-hour
fumigation stage was completed, the formaldehyde neutralized, and the tent ventilated, the postal
equipment was operated in order to aerosolize any spores remaining within the two machines so
that these residual spores would be susceptible to destruction in the second fumigation stage.

Following the remedial activities, the success of the remediation was determined through
environmental sampling, mostly surface wipe sampling but also including some vacuum sock
sampling. All samples were negative for growth of B. anthracis.

After the environmental sampling had proven negative for B. anthracis, the  fumigated sorting
machine was disassembled and further wiped clean prior to re-use.

5.3.5   Concerns for the User

From a practical standpoint, concerns for paraformaldehyde are similar to those for
formaldehyde. This is because paraformaldehyde will generate gaseous formaldehyde during
storage or use. If it gets in contact with water, paraformaldehyde will similarly break down to
formaldehyde. In addition, toxicological data or health concerns regarding paraformaldehyde
are not readily available.  For these reasons, information in this section will be generally limited
to formaldehyde.

Formaldehyde has been identified as a probable human carcinogen by EPA, based on limited
evidence of carcinogenicity in  humans through inhalation exposure, and sufficient evidence for
carcinogenicity in experimental animals. It produces nasal carcinomas in rats (EPA, 2003).
Acute effects include respiratory irritation.

Airborne occupational exposure limits for formaldehyde applicable to the United States are as
follows (NIOSH, 2003):

             NIOSH REL 8-hour TWA 0.016 ppm (0.02 mg/m3)
             OSHA PEL 8-hour TWA 0.75 ppm (0.92 mg/m3)
             ACGIH TLV 15-minute short term exposure limit (STEL) ceiling 0.3 ppm (0.4
             mg/m3)
       •      Immediately Dangerous to Life or Health (IDLH) Level 20 ppm (25 mg/m3).

These exposure limits are several orders of magnitude below the concentrations used for
decontamination as discussed above.  Therefore, following decontamination, steps must be taken
to completely neutralize excess formaldehyde in the air as well as to similarly remove any
chemical which may have condensed onto surfaces. Formaldehyde is a flammable, colorless gas
(lower explosive limit of 7 percent) with a pungent odor, all of which reflect additional concerns
during use.  Crystal paraformaldehyde itself is also combustible, with a flash point of 70 °C.

                                          163

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While the lower explosive limit and the flash point are well above the typical concentration and
temperature conditions encountered during use, precautions must be taken for the possibility of
extreme localized conditions in a room (e.g., in the immediate vicinity of the gas generation
source or in a poorly ventilated area within a room). Formaldehyde gas has a density only
slightly higher than that of air (relative vapor density 1.04); because of this similarity no
significant difficulties in inking or partitioning would be expected.

Caution must be taken while handling paraformaldehyde as it decomposes to formaldehyde gas
on contact with water or moist air. Personal protection  and exposure controls to be employed
while handling paraformaldehyde include the use of chemical goggles, full-face shield or a full-
face respirator, impervious gloves and boots of chemically resistant material, and body suits,
aprons, or coveralls of chemical resistant material.  Ventilation requirements for the use of
paraformaldehyde include mechanical ventilation, process or personnel enclosure, and control of
process conditions.  There should also be a sufficient supply of replacement air to make up for
air removed by exhaust systems (ClearTech, 2003).

5.3.6  Availability of the Technology for Commercial Applications

This technology is readily available for commercial applications. The heating and dispersion of
paraformaldehyde is relatively straightforward.  Technology for preparation (e.g., sealing
buildings) is routine and similar to what is required for other fumigants. Personal protective
equipment requirements are similar to other toxic materials.  Monitors for formaldehyde gas
(providing real-time data) are commercially available.

As indicated previously, paraformaldehyde can be dispersed using a specially-designed
generator or a series of low-cost hotplates. Generator cost varies based on size requirements.
The largest available generator by one manufacturer, Certek, is designed to decontaminate a
10,000 ft3 (280 m3) area with a concentration of 10.6 g/m3 (identified as the NIH recommended
level).  Room volume and concentration are related, so that if a lower concentration is targeted, a
larger room could be decontaminated. The cost for this type of generator is approximately
$60,000 and the cost of paraformaldehyde is approximately $24/ pound for small quantities
(bulk chemical quantities are cheaper) (SAIC, 2003).  As an example, approximately six pounds
of paraformaldehyde would be  required in decontaminating a room volume of 280 m3 at a
concentration of 10.6 g/m3.  In decontaminating a larger area such as a building, either multiple
generators could be used or the area can be decontaminated in sections.

5.3.7  Advantages and Disadvantages

Paraformaldehyde and formaldehyde have been used for equipment and room decontamination
for many years and therefore benefit from having a 'track record.' Advantages of formaldehyde
gas (such as that generated from paraformaldehyde) include that it is a powerful disinfectant,
noncorrosive to metals, and relatively  easy to generate from either paraformaldehyde or formalin
(Coldiron and Janssen, 1984).

A principal disadvantage is that - unlike the other fumigants covered in this report -
formaldehyde is a probable human carcinogen. The other fumigants are toxic at fumigation
                                           164

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concentrations, but they have not been adequately studied to determine carcinogenicity, and thus
are of lower-level concern.

5.3.8  Potential Areas for Future Research

Although vapor formaldehyde sterilization has been studied for many years, there is some
disparity regarding the concentrations needed to achieve effective decontamination. For
example, studies by Munro et al. (1999) identified an optimum concentration as 10,500 mg/m3
for organisms such as B. subtilis, while other studies such as Lach (1990) identified that
concentrations in the range of 100 to 1,000 mg/m3 were effective for B. globigii. The
combination of gas concentration, relative humidity, temperature, and contact time that is
optimally effective for inactivating B. anthracis and surrogates needs to be determined.

In addition, most data available are for organisms on spore strips or on nonporous substrates
such as metal. The effectiveness of paraformaldeyde appears to vary, depending on the
composition and porosity of the surface being treated. There is a need to better quantify the
efficacy of this fumigant on a variety of hard, non-porous (e.g., metal, painted surfaces, glass)
and porous (e.g., wood, carpeting) surfaces.

Further studies are needed of the effects of formaldehyde on the functioning and lifetime of
sensitive electronic equipment.

5.3.9  References for Section 5.3

Alexander, 1998.  Alexander, Lexi.  "Decontaminating Civilian Facilities: Biological Agents and
Toxins." Institute for Defense Analysis, unpublished report.

Bovallius and Anas, 1977.  Bovallius, A.; and Anas, P. "Surface-Decontaminating Action of
Gluteraldehyde in the Gas-Aerosol Phase," Appl Environ. Microbiol, 34(2): 129 (1977).

Caputo and Odlaug, 1983.  Caputo,  R. A; and Odlaug, T. E. "Sterilization with Ethylene Oxide
and Other Gases." In Disinfection,  Sterilization, and Preservation, 3rd edition (S. S. Block, ed.),
p. 47. Lea & Febiger, Philadelphia, PA, 1983.

Certek, 1980.  "Apparatus for biological decontamination and subsequent neutralization of a
space," U.S. Patent No. 4241020, James Grantham (Certek, Inc.). December 23,1980.

ClearTech, 2003.  Material Safety Data Sheet: Paraformaldehyde, ClearTech Industries Inc.
www.ClearTech.ca/inside/tnsds/pfmd-04-07-2003.pdf. Accessed December 2004.

Coldiron and Janssen, 1984. Coldiron, V.R.; and Janssen, H. Erie. "Safe Decontamination of
Hospital Autopsy Rooms and Ventilation System by Formaldehyde Generation." Am. Ind. Hyg.
Assoc. J., 45(2); 136-137 (1984).

EPA, 2004.  Formaldehyde. Integrated Risk Information System (IRIS), U.S. Environmental
Protection Agency.  Available at: www.epa.gov/iris/subst/0419.htm.  Accessed December 2004.
                                          165

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EPA, 2004.  U.S. Environmental Protection Agency: Pesticides - Topical and Chemical Fact
Sheets: Paraformaldehyde.  Available at:
vTOw.epa.gov/pesticides/factsheets/chemicals/parafornialdehvde factsheet htm. Accessed
December 2004.

Hoffman and Spiner, 1970. Hoffman, Robert K.; and Spiner, David R. "Effect of Relative
Humidity on the Penetrability and Sporacidal Activity of Formaldehyde." Applied Microbiology
20 (4): 616-619 (1970).

Hoxey et al., 1985. Hoxey, E.V.; Soper, C.J.; and Davies, D.J.G. "Biological Indicators for Low
Temperature Steam Formaldehyde Sterilization: Effect of Defined Media on Sporulation,
Germination Index and Moist Heat Resistance at 110 °C of Bacillus Strains." Journal of Applied
Bacteriology, 58: 207-214 (1985).

Kirk-Othmer, 1994. Encyclopedia of Chemical Technology, Fourth Edition, Volume 11,
"Formaldehyde." Page 931.

Klein and Deforest, 1983. Klein, M.; and Deforrest, A. "Principles of Viral Inactivation." In
Disinfection, Sterilization, and Preservation, 3rd edition (S.  S. Block, ed.), p. 422. Lea&
Febiger, Philadelphia, PA, 1983.

Lach, 1990.  Lach, V.H.  "A Study of Conventional Formaldehyde Fumigation Methods."
Journal of Applied Bacteriology, 68: 471-477 (1990).

Manchee et al., 1994.  Manchee, Richard J.; Broster, Malcolm G.; Stagg, Anthony 1; and Hibbs,
Stephen E. "Formaldehyde Solution Effectively Inactivates  Spores of Bacillus anthracis on the
Scottish Island of Gruinard." Applied and Environmental Microbiology., 60: 4167-4171 (1994).

Munro et al., 1999, Munro, Kerry; Lanser, Janice; and Flower, Robert  "A Comparative Study
of Methods to Validate Formaldehyde Decontamination of Biological Safety Cabinets." Applied
and Environmental Microbiology, 65:  873-876 (1999).

NIH, 1979. Laboratory Safety Monograph: A Supplement to the NIH Guidelines for
Recombinant DMA Research.  National Institutes of Health,  U.S. Department of Health,
Education, and Welfare.  Washington, D.C.

NIOSH, 2003. NIOSHPocket Guide to Chemical Hazards,  Publication No. 97-140. US.
Department of Health and Human Services.  Washington, D.C.

NSF, 2002. NSF/ANSI49-2002, Annex G. Recommended microbiological decontamination
procedure: Class II (laminar flow) biosafety cabinetry.  National Science Foundation and the
American National Standards Institute.  Washington, D.C.

SAIC, 2003. Personal communication with Jim Grantham, Certek Inc., Raleigh, NC. August 8,
2003.
                                         166

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Taylor et al., 1969.  Taylor, Lany A.; Barbeito, Manuel S.; Gremillion, Gardner G.
"Paraformaldehyde for Surface Sterilization and Detoxification." AppliedMicrobiolgy, 17: 614-
618 (1969).

USAMRIID, 1999.  USAMRIID Regulation 385-17, Decontamination of Containment Areas
with Formaldehyde. U.S. Army Medical Research Institute of Infectious Diseases. Fort Detrick,
MD (February 19,1999).

Wickramanayake, 1990. Wickramanyake, G.B. "Decontamination Technologies for Release
from Bioprocessing Facilities - Part IV: Decontamination of Equipment/ Surfaces." Critical
Reviews in Environmental Control, 19 (6): 481-513 (1990).
I
                                         167

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5.4    Methyl Bromide

Methyl bromide is a broad spectrum pesticide. It has been registered under FIFRA as a ftimigant
for termites, insects, and rodents in buildings, and as a fumigant for agricultural applications. It
is known to deplete stratospheric ozone, and is being phased out of some of its applications for
that reason.

Methyl bromide, like formaldehyde,  appears to function by an alkylation mechanism, rather than
by oxidation (as C102 and H2O2 do).  It has never previously been registered as a sporicide, but
recent interest in its possible efficacy against B. anthracis (BA) spores has been triggered by the
2001 anthrax mail incident.

5.4.1   Description of the Technology

Following the anthrax mail incident,  University of Florida researcher Dr. Rudolf Scheffrahn
proposed the application of methyl bromide for the building remediation of BA spores.  Tests
were conducted, with reportedly favorable results, using simulant spore strips in an office-like
setting. A patent application has been filed for the use of methyl bromide as a building fumigant
for bacterial contamination (Scheffrahn, 2002). The patent application is under evaluation.

5.4.2   Technical Maturity

Methyl bromide is fully mature in the applications for which it has been registered (fumigation
of structures for insects and rodents, and soil fumigation).  However, it is still in the
experimental stage for use against B. anthracis spores.

5.43   Applications of the Technology

Methyl bromide gas is most frequently used as a gas fumigant against termites, rodents and
nematodes. The majority of use in the US (approximately 85 percent) is for pesticide
applications involving soil sterilization (EPA, 2004a).  Removal of soil organisms enhances crop
yields. Of those applications, most is used for the cultivation of tomatoes and strawberries.
Methyl bromide is injected into the soil at a depth of 12-24 inches with the presence of a plastic
vapor barrier on top of the soil to restrict the entry of the gas into the atmosphere. While the
plastic sheeting slows the release of the gas into the atmosphere, it is estimated that the majority
of the gas escapes into the air environment.

Ten percent of the remaining use is for commodity and quarantine fumigation. Methyl bromide
is also used to decontaminate the exterior of imported produce such as grapes, nuts, cherries, etc.
When used as such the materials are placed in a tent and the methyl bromide is released into the
tented structure.

Only five percent of the use is for structural fumigation for rodent and  termite control. A
building is tented and methyl bromide is released into the structure. While the methyl bromide is
not very effective against ground resident termites, it is effective against those that reside in the
upper portions of the structure.


                                           168

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Methyl bromide is used in almost all parts of the world. Annual consumption figures for soil
fumigation are provided in Table 5.4-1 (Champon, 2004). The United States is clearly the
largest user of this fumigant. Although these figures are not current (they are from 1996), they
do illustrate a global usage for agriculture.

Table 5.4-1. Global Methyl Bromide Pre-Plant Soil Fumigation:  Usage of Methyl Bromide
for Pre-plant Soil Applications by Country (1996)
Country
United States
Japan
Italy
Israel
Spain
France
Brazil
Turkey
Mexico
Zimbabwe
Morocco
Other
Total Pre-olant
Methyl Bromide
Consumption
(metric tons)
15,839
6,345
6.00C
2,800
2,670
1,428
1.26C
950
900
765
48C
8,461
47.897
Methyl Bromide
Consumption Qbs.)
34,908,05^
13,984,38(
13,224,00(
6,171,20(
5,884,68(
3,146,34:
2,777,04(
2,093,80<
1,983,60<
1,686,06C
1,057,92(
18,648,04^
105.565. 12<
                   jSourcesiUNEP, 1995, ICF, 1997.
5.4.4   Evaluation of Available Data

Methyl bromide was reported to be toxic to B. anthracis spores over 50 years ago (Kolb and
Schneiter, 1950).  Additional literature reports in the late 1970s by Russian scientists also
documented the ability of methyl bromide to kill BA spores (Pilipenko, 1976; Poryakov et al.,
1976). Chemical methods for spore remediation were well established for laboratory fumigation
(paraformaldehyde) and there was not a pressing need to remediate large structures. Thus this
work appeared to go relatively unnoticed until the terrorist acts of sending BA spores through the
mail.  Contamination of buildings with BA spores changed the conventional wisdom and new
methods were sought for large-scale remediation operations.

Dr. Rudolf Scheffrahn, at the University of Florida, Ft. Lauderdale Research  and Education
Center, began evaluation of methyl bromide for bacterial spore inactivation.  Dr. Scheffrahn
provided documentation of experiments he conducted or contracted to evaluate the effect of
methyl bromide on bacterial spores (Scheffrahn and Weinberg, 2003). Excerpts from those
documents are included in this section of the report.

Scheffrahn and Weinberg conducted a series of laboratory experiments where they evaluated the
effect of methyl bromide on spores from Bacillus subtilis var. niger (BSN) and Bacillus
stearothermophilus (BST). Spore strips containing either 105 BST, 106 or 108 BSN were
exposed to methyl bromide.  Variables included temperature, time, and concentration of methyl
bromide. After incubation the spore strips were removed from their protective envelopes and
                                          169

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r>
               transferred into tubes containing growth media, and incubated at the appropriate temperatures for
               growth of the respective organisms. If there was no growth after one-week incubation the data
               were scored as "pass" if growth was observed, the data were scored as "fail." Results are
               illustrated in Table 5.4-2, which shows the germination of Bacillus stear other mophilus 10s and
               B. subtilis 106 combination spore strips after exposure to methyl bromide in 9-liter glass
               chambers under'selected concentration, temperature, and time conditions.  Each row represents a
               single chamber exposure, two strips each.
               Table 5.4-2. Spore Germination After Methyl Bromide Exposure
                                                                          Spore Germination: Pass/Fail
Exposure
Date
27NovOI
27Nov01
27Nov01
27Nov01
27Nov01
27Nov01
27Nov01
lODecOl
lODecOl
lODecOl
lODecOl
lODecOl
lODecOl
lODecOl
ISDecOl
ISDecOl
ISDecOl
ISDecOl
ISDecOl
ISDecOl
ISDecOl
Temp
19
19
19
19
19
19
19
20
20
20
27
' 27
27
27
27
27
32
32
32
32
32
MB cone.2
(mg/L)
48
48
48
80
80
80
160
240
320
320
240
320
320
320
320
320
160
240
240
320
320
Time
(hours)
63
104
146
112
134
164
164
48
72
96
48
72
96
96
48
62
72
48
72
38
47
Accum. Dose
(mg-hr/L)
3,000
5,000
7,000
9,000
1 1,000
.13,120
26,240
11,520
23,040
30,720
11,520
23,040
30,720
30,720
15,360
19,776
1 1,520
11,520 -
17,280
12,160
15,104
B. stearo.
fail
fail
fail
pass
pass
pass
pass
nt3
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
B. subtilis
stripl
fail
fail
fail
fail
fail
fail
fail
fail
fail
fail
fail
fail
pass
pass
pass
pass
fail
pass
pass
pass
pass
strip2







•



pass
pass
pass4
pass
pass
fail
pass
pass
pass
pass
                lMean±0.4°C.
                2 Theoretical concentration based on MB volume introduced. Actual concentration is lower.  Methyl bromide is a
                colorless and odorless gas at concentrations harmful or lethal to humans and must be handled with extreme caution by
                certified personnel. The American Conference of Government Industrial Hygienists (ACGIH) threshold limit value
                (TLV) for human exposure to methyl bromide is 1 ppm (v/v, 8-hour time-weighted average) (equivalent to 0.004
                mg/L) (ACGIH, 2002). The concentrations tested here (48 to 320 mg/L) correspond to 12,500 to 80,000 ppm.
                5 nt = not tested. In these tests, both strips were tested for B. subtilis germination.
                4 Chamber contained office commodities listed in text.
                                                               170

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                                                                                            \
Figures 5.4-3 through 5.4-5 show spore strip placements. The trailer was prepared for methyl
bromide fumigation by covering with two tarpaulins that are clamped together and sealed to the
ground with sand "snakes" as shown in Figure 5.4-6.
Figure 5.4-3. Spore strip sites 1 and 2 (see Table 1). Clockwise from top left: Strips in sub
floor ducting under vent; vent in place.  Strips under carpet; carpet in place.
 Figure 5.4-4. Spore strip site
     13. Left: strips under
          mattress.
Right: mattress in place.
                                          173

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Figure 5.4-5. Spore strip site 3. Left: strips inside wall insulation.  Right: paneling in
place.
            Figure 5.4-6. The Prepared Trailer
                                        174

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Methyl bromide was introduced into the trailer and circulated with fans. Heaters were utilized to
keep temperatures elevated.  Methyl bromide concentration was monitored, and additional gas
was added when the levels fell below optimal concentration. The profile of methyl bromide
concentration is graphed in Figure 5.4-7.  As shown, the average MB concentration during
fumigation was 303.7 oz per  1,000 ft3 (equivalent to approximately 307 mg/L, or 80,000 ppm).

                 i!ifi!4^

              li!JlHlh;!!MiiiH!li!l$llil!!;il!l2ffi;£
                                           lliilJiiiiji
              Figure  5.4-7.  Methyl  Bromide  Concentration During
              Trailer Fumigation and Aeration
Following aeration the spore strips were removed and analyzed for growth.  The results are
indicated in the table below. Out of 80 spore strips, four demonstrated positive growth. The
four strips that resulted in growth contained 108 BSN spores.  It is important to note that the
higher density spore strips were placed in duplicate. In all cases the duplicate of the spore strip
that demonstrated growth had no growth. These results are consistent with a threshold kill in
these locations. All four of these locations were in hard to reach locations: inside ducting, in a
closed folder on floor, under a mattress, and in a closed closet.

The results of this study suggest that methyl bromide can be an effective fumigant against these
surrogate organisms.  The apparent ability of methyl bromide to penetrate porous materials
without discoloration is a very encouraging observation.

Following these favorable results, the authors requested EPA funding to evaluate methyl
bromide against Bacillus cmthracis spores in a laboratory environment. The resulting report is
reprinted in Figure 5.4-8.
                                           175

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o
n
              Table 5.4-4. Spore Strip Location, Proximal Ambient Temperature Conditions, and
              Incubation Results for 80 Strips After Exposure for 48 Hours to Methyl Bromide at a
              Concentration of 303.7 oz/1,000ft3 in Trailer
                            (Pass = No Spore Germination Occurred; Fail = Spore Germination Occurred)
                                                Exposure Temperatures "F
106      10s      B. subtilis 10"
Trailer Location No. and Description
1 -Floor vent, inside ducting
2-Under carpet fabric
3-Behind wall paneling in insulation
4-Wall plug outlet, covered
5-Wall surface, in closed folder
6-Closed kitchen cabinet
7-PC keyboard, inside back cover
8-PC CD tray, closed
9-Desk drawer, closed
10-Desk drawer, in closed hanging file
1 1 -Ceiling surface, exposed
12-FIoor surface, in closed folder
13-Mattress, under box spring
14-Hall closet, closed
15-Medicine cabinet, closed
16-Light fixture, secured globe
17-Central AC inlet, behind filter
18-WindowAC, behind filter
1 9-Und er newsp apers
20-Recliner chair, under cover fabric
Mean
95.12
95.12
95.12
95.12
95.12
95.07
95.07
95.07 .
95.07
95.07
95.07
95.07
95.07
90.29
90.29
90.29
90.29
93.24
93.24
95.12
Max.
98.8
98.8
98.8
98.8
98.8
98.8
98.8
98.8
98.8
98.8
98.8
98.8
98.8
94.1
94.1
94.1
94.1
100.2
100.2
98.8
Min.
89.6
89.6
89.6
89.6
89.6
89.6
89.6
89.6
89.6
89.6
89.6 ,
89.6
89.6
83.6
83.6
83.6
83.6
88.2
88:2
89.6
B. sub.
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
. pass
pass
pass
pass
pass
pass
pass
B. stear.
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
Strip A
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
pass
fail
fail
pass
pass
pass
pass
pass
pass
Strip B
fail
pass
pass
pass
pass
pass
pass
pass
pass
'pass
pass
fail
pass
pass
pass
pass
pass
pass
pass
pass
              The three sets of experiments by Dr. Scheffrahn summarized above suggest that methyl bromide
              may be an effective fumigant against Bacillus spores. The data are consistent and supportive of.,
              further examination into the possibility of using methyl bromide for the remediation of buildings
              contaminated with biological materials.  (A fourth test in the trailer, utilizing a slightly lower
              MB concentration, provided more ambiguous results regarding spore kill, which had not been
              explained at the time of this writing; this underscores the need for further testing.)

              Little data were found regarding reactivity of methyl bromide with common building elements
              such as paints and fabrics. It is reported incompatible with aluminum, dimethyl sulfoxide, strong-
              acids, strong oxidizers, strong bases, nitrates, and alkaline earth metals according to the
              Materials Safety Data Sheet (MSDS). Thus, methyl bromide may affect some materials found in
              homes or buildings.
n
                                                         176

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in either male or female mice. However, significant neurological effects were noted in nice at
the highest dose (NTP, 1992).

It is estimated that between 50 and 95 percent of the methyl bromide used to fumigate structures
to rid rodents and insects ends up in the atmosphere (EPA, 2004a).  Methyl bromide release to
the atmosphere is a serious consideration. Due to the effect of methyl bromide on ozone
depletion, the gas will be phased out for U.S. operations by 2005 as a result of the Clean Air Act
and Montreal Protocol. In spite of the phase out for most commercial applications, the chemical
will still be available for critical agricultural and emergency uses in the U.S. The use of methyl
bromide as a fumigant for biological warfare contamination of a building is considered an   •
emergency application.

Methyl bromide is a stable gas and is dispersed into the atmosphere following pesticidal
fumigations. This property is a distinguishing factor from paraformaldehyde, vapor-phase
hydrogen peroxide, and chlorine dioxide, all of which either self decompose or are neutralized
by the introduction of another chemical at the completion of the fumigation.

Venting of highly toxic methyl bromide to the atmosphere is currently legal under current EPA-.
registered pesticide applications of this product.  However, given the large amounts of very high-
concentration gas (about 80,000 ppm) that could be present in a building being fumigated for B.
anthracis sterilization, the venting of this building air may raise concerns, especially in densely
populated areas. Given the TLV value of 1 ppm, and given prior experience with the oxidizing  .
fumigants discussed in the previous chapters,  a methyl bromide concentration at the building's
fence-line would probably need to be maintained at a value below 1 ppm.  Unless a reliable
technology is demonstrated for removing methyl bromide from the building air being vented,
and if dilution alone is to be relied upon to protect neighboring populations, a substantial dilution
of the exhaust air would be required to meet the desired fence-line concentrations.

A method of removing methyl bromide from the building air that is vented outdoors is thus
crucial, not only from the standpoint of its ozone-depleting characteristics, but from the
standpoint of the health issues raised above. The absence of a demonstrated approach for
sorbing or otherwise destroying methyl bromide prior to release is a major issue that needs to be
addressed.

5.4.6  Availability of the Technology for Commercial Applications

Methyl bromide is registered by EPA as a pesticide, and is available for commercial applications
as a pesticidal fumigant in buildings and agricultural applications. However, the compound is
not registered as a sporicide. A patent application has been filed in the U.S. for the use of
methyl bromide against bacterial spore contamination in buildings. A final decision regarding
the patent application has not been made. And, as discussed above, additional data appear to be
required before this fumigant could be safely utilized for bacterial sterilization of large buildings.

The application of methyl bromide is relatively straightforward. Monitors for the gas levels,
both inside and outside buildings are commercially available.
                                           179

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Methyl bromide is a stable gas. As demonstrated irVtne trailer test, gas must be added  '
periodically to structure in order to make up for leakage, demonstrating the need for highly
effective sealing of the enclosure being fumigated.  Three additions of approximately fifteen
percent of the original load were required over a forty-eight hour period to compensate for
leakage through and under the tarps over the trailer. The cost of methyl bromide gas is projected
by the developers to be low compared to the cost of generating and distributing chlorine dioxide
or hydrogen peroxide vapor into a structure.

The common practice when using methyl bromide for building fumigation for pest control is to
let the gas vent into the atmosphere.  However, if the gas is to be used at concentrations on the
order of 80,000 ppm for treatment of large buildings that must be kept at negative pressure, an
effective means for scrubbing the methyl bromide from the building air before release is critical;
to remove concerns about damage to the ozone layer and potential exposure of humans in the
vicinity.

5.4.7  Advantages and Disadvantages

The main advantage of this technology is that it appears to be effective against Bacillus
anthracis and surrogate bacillus species under conditions that are achievable at a  small building
scale. The log kill obtained in laboratory and field trials meets or exceeds the EPA sterilization
requirement.  The ability of the gas to penetrate porous surfaces and any cracks or crevices
demonstrates that the gas will reach all locations that a spore could reach. The gas does not
appear to discolor photographs or printed material.

The main disadvantage of methyl bromide is the potential for human exposure to the highly toxic
gas and the potential for ozone layer damage, unless a method can be developed to neutralize or
scrub the methyl bromide from the air that is vented from a structure during and following
fumigation. In addition, 50 to almost 400 time higher concentrations of methyl bromide must be
used to fumigate for B. anthracis,  compared to the required concentrations for the other three
fumigants covered in this report, and 4 to 12 times longer contact times are needed.

Methyl bromide is scheduled for phase-out in some of the applications for which it is currently
registered by 2005.  However, research is currently continuing into its applicability for anthrax
decontamination in buildings, to determine whether it offers potential (e.g., due to its
penetrability) such that perhaps it should remain available for such emergency applications.

5.4.8  Potential areas for future research

The preliminary data for methyl bromide killing of Bacillus spores suggests potential, but
significant additional efficacy data are required over a range of conditions. In addition, there is a
compelling need for development and demonstration of a means for removal of methyl bromide
from the air exhausted from a building during and after fumigation, to protect people from its
toxic effects and to prevent depletion of the stratospheric ozone layer.  Furthermore, rigorous
engineering analysis is required to evaluate the issues involved in scaling up the methyl bromide
fumigation technology, from residential pest-control applications to large-building biological
decontamination applications.
                                           180

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Methyl bromide is a stable gas. As demonstrated in the trailer test, gas must be added
periodically to structure in order to make up for leakage, demonstrating the need for highly
effective sealing of the enclosure being fumigated.  Three additions of approximately fifteen
percent of the original load were required over a forty-eight hour period to compensate for
leakage through and under the tarps over the trailer. The cost of methyl bromide gas is projected
by the developers to be low compared to the cost of generating and distributing chlorine dioxide
or hydrogen peroxide vapor into a structure.

The common practice when using methyl bromide for building fumigation for pest control is to
let the gas vent into the atmosphere.  However, if the gas is to be used at concentrations on the
order of 80,000 ppm for treatment of large buildings that must be kept at negative pressure, an
effective means for scrubbing the methyl bromide from the building air before release is critical,
to remove concerns about damage to the ozone layer and potential exposure of humans in the
vicinity.

5.4.7  Advantages and Disadvantages

The main advantage of this technology is that it appears to be effective against Bacillus
anthracis and surrogate bacillus species under conditions that are achievable at a small building
scale. The log kill obtained in laboratory and field trials meets or exceeds the EPA sterilization
requirement.  The ability of the gas to penetrate porous surfaces and any cracks or crevices
demonstrates that the gas will reach all locations that a spore could reach. The gas does not
appear to discolor photographs or printed material.

The main disadvantage of methyl bromide is the potential for human exposure to the highly toxic
gas and the potential for ozone layer damage, unless a method can be developed to neutralize or
scrub the methyl bromide from the air that is vented from a structure during and following
fumigation. In addition, 50 to almost 400 time higher concentrations of methyl bromide must be
used to fumigate for B. anthracis, compared to the required concentrations for the other three
fumigants covered in this report,  and 4 to 12 times longer contact times are needed.

Methyl bromide is scheduled for phase-out in some of the applications for which it is currently
registered by  2005.  However, research is currently continuing into its applicability for anthrax
decontamination in buildings, to determine whether it offers potential (e.g., due to its
penetrability) such that perhaps it should remain available for such emergency applications,

5.4.8  Potential areas for future research

The preliminary data for methyl bromide killing of Bacillus spores suggests potential, but
significant additional efficacy data are required over a range of conditions. In addition, there is a
compelling need for development and demonstration of a means for removal of methyl bromide
from the air exhausted from a building during and after fumigation, to protect people from its
toxic effects and to prevent depletion of the stratospheric ozone layer.  Furthermore, rigorous
engineering analysis is required to evaluate the issues involved in scaling up the methyl bromide
fumigation technology, from residential pest-control applications to large-building biological
decontamination applications.
                                           180

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Because methyl bromide is a strong alkylating agent, it may be interesting to perform
preliminary studies to evaluate its effect on chemical warfare agents. If methyl bromide is
effective against chemical warfare agents, it might be a candidate for broad spectrum
remediation (addressing both chemical and biological agents).

5.4.9  References

ACGIH, 2002. Threshold Limit Values for Chemical Substances and Physical Agents.
American Conference of Governmental Industrial Hygienists,  Cincinnati, OH.

Champon, 2004. Champon Millennium Chemicals, Inc. Methyl Bromide.
http://www.champon.com/about/nietbromide.htm. Accessed December 2004.

EPA, 2004a.  U.S. Environmental Protection Agency. Ozone Depletion Rules and Regulations:
Methyl Bromide Questions & Answers. Available at:
http://www.epa.gov/docs/ozone/mbr/qa.html. Accessed December 2004.

EPA, 2004b.  U.S. Environmental Protection Agency. Integrated Risk Information System:
Bromomethane (CAS 74-83-9).  http://www.epa gov/iris/subst/0015.htm. Accessed December
2004.

ICF, 1997.  "U.S. Methyl Bromide Alternatives Consumption  Trends." Memorandum prepared
for the U.S. Environmental Protection Agency,,Stratospheric Protection Division.  ICF, Inc.
Washington, DC.  January 31,1996.

Kolb and Schneiter, 1950. Kolb, R. W.; and Schneiter, R. "The germicidal and sporicidal
efficacy of methyl bromide for Bacillus anthracis." Journal of Bacteriology, SO: 401-412 (1950).

NTP, 1992. Toxicology and Carcinogenesis Studies of Methyl Bromide (CAS No. 74-83-9) in
B6C3Fi Mice (inhalation studies).  National Toxicology Program Report NTP TR 385, National
Institutes of Health Publication No. 92-2840.

Pilipenko, 1976. Pilipenko, A. V.  "Disinfection of soil sources of Bacillus anthracis with
methyl bromide." Vses. Nauchno-Issled. Inst. Vet. Sanit., 54:138-4 (1976).  (In Russian; only
the English abstract was reviewed).

Polyakov et al., 1976,  Polyakov, A. A. A.; Kulikovskii, V.; and Pilipenko, A.V.
"Submicroscopic structure of Bacillus anthracis spores subjected to methyl bromide treatment."
Dokl Vses. Akad. S-kh. Nauk, 12: 23-4 (1976).  (In Russian; only the English abstract was
reviewed).

Scheffrahn and Weinberg, 2003. Scheffrahn, Rudolf H.; and Weinberg, Mark J.  "Structural
Fumigation with Methyl Bromide for Control of Bacillus Spores: Field Demonstration with B.
subtitis and B. stear other mophilus"  Personal communication with SAIC, July 2003.
i
                                          181

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Scheffrahn, 2002. Scheffrahn, R. H. "Method of Decontamination of Whole Structures and
Articles Contaminated by Pathogenic Spores." U.S. Patent Application No. 20030129082, filed
March 28, 2002.

UNEP, 1995.1994 Report of the Methyl Bromide Technical Options Committee, prepared under
Montreal Protocol on Substances that Deplete the Ozone Layer
(http://w\\'\v.unep.org/ozone/teap/Reports/HTOC/HTOC94.PDF. accessed December 2004).
United Nations Environment Programme.
                                        182

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^United States
 Environmental Protection
 Agency

 Office of Research and Development
 National Homeland Security Researdi Center
 Cincinnati, OH 45268

 Office Business
 Penalty for Private Use
 $300

 EPA/600/R-05/036   <
 March 2005'
 www.epa.gov/nhsrc
                                                                PRESORTED STANDARD
                                                                POSTAGE & FEES PAID
                                                                        EPA
                                                                   PERMIT No. G-35
         Recyclcd/Rceyelghh!
         Printed wKh vegetable-based ink on
         paper thai contains a nunlm urn of
         50% post-consumer flbcr contoit
         processed cniorine frc-c

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