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Liu X.,National Risk Management Research Laboratory | Guo Z.,National Risk Management Research Laboratory | Sparks L.E.,National Homeland Security Research Center | Roache N.F.,Arcadis
Indoor and Built Environment | Year: 2011

The event of 11 September 2001 underscored the need to study the vulnerability of buildings to weapons of mass destruction, including chemical, biological, physical and radiological agents. Should these agents be released inside a building, they would interact with interior surfaces, building materials and furnishings, and could remain for a long period in an indoor environment. This study provides insights into the sink effect and absorption mechanisms of volatile organic compounds (VOCs) in indoor environments. In this study, the sink effect was investigated with building materials (e.g. painted gypsum wallboard, vinyl flooring, carpet and mortar) and VOCs, ethylbenzene, 1-butanol, decane and dodecane, which were used as surrogates of toxic chemicals. Vinyl flooring has the strongest sink for ethylbenzene and dodecane. The sink experimental data were employed to evaluate the Langmuir-isotherm and diffusion sink models. Test data were also compared to a no-sink model. The sorption and desorption rate constants for the Langmuir-isotherm model were obtained. Mass balance was analysed. There were strong correlations between equilibrium partition coefficients from the Langmuir-isotherm model and equilibrium partition coefficients and the effective diffusion coefficients from the sink diffusion model. © The Author(s), 2011.


Calfee M.W.,National Homeland Security Research Center | Wendling M.,Batelle Memorial Institute
Science of the Total Environment | Year: 2013

Following a wide-area biological terror attack, numerous decontamination technologies, techniques, and strategies will be required for rapid remediation. Establishing an understanding of how disinfectants will perform under field conditions is of critical importance. The purpose of this study was to determine the efficacy of several liquid decontaminants, when used to inactivate vegetative biological agents on environmental surfaces. Aluminum, carpet, concrete, glass, and wood coupons were inoculated with 1×108CFU of Burkholderia mallei, Francisella tularensis, Vibrio cholerae, or Yersinia pestis. Using spray-based application methods, decontamination was then attempted with pH-adjusted bleach, 1% citric acid, 70% ethanol, quaternary ammonia, or Pine-Sol®. Results indicated that decontamination efficacy varied significantly by decontaminant and organism. Materials such as wood are difficult to decontaminate, even when using sporicides. The data presented here will help responders develop efficacious remediation strategies following a large-scale contamination incident. © 2012.


Calfee M.W.,National Homeland Security Research Center | Wendling M.,Batelle Memorial Institute
Letters in Applied Microbiology | Year: 2015

Five commercially available liquid antimicrobials were evaluated for their ability to decontaminate common environmental surface materials, contaminated with Burkholderia pseudomallei, using a spray-based disinfectant delivery procedure. Tests were conducted at both an ambient temperature (c. 20°C) and a lower temperature (c. 12°C) condition. Nonporous materials (glass and aluminium) were more easily decontaminated than porous materials (wood, concrete and carpet). Citric acid (1%) demonstrated poor efficacy in all test conditions. Bleach (pH-adjusted), ethanol (70%), quaternary ammonium and PineSol®, demonstrated high (>6 log10 reduction) efficacies on glass and aluminium at both temperatures, but achieved varying results for wood, carpet and concrete. Temperature had minimal effect on decontamination efficacy during these tests. Significance and Impact of the Study: Much of the antimicrobial efficacy data for pathogenic micro-organisms are generated with testing that utilizes hard nonporous surface materials. These data are not directly translatable for decontaminant selection following an incident whereby complex and porous environmental surfaces are contaminated. This study presents efficacy data for spray-applied antimicrobial liquids, when used to decontaminate common environmental surfaces contaminated with Burkholderia pseudomallei. These data can help responders develop effective remediation strategies following an environmental contamination incident involving B. pseudomallei. Significance and Impact of the Study: Much of the antimicrobial efficacy data for pathogenic micro-organisms are generated with testing that utilizes hard nonporous surface materials. These data are not directly translatable for decontaminant selection following an incident whereby complex and porous environmental surfaces are contaminated. This study presents efficacy data for spray-applied antimicrobial liquids, when used to decontaminate common environmental surfaces contaminated with Burkholderia pseudomallei. These data can help responders develop effective remediation strategies following an environmental contamination incident involving B. pseudomallei. © 2015 The Society for Applied Microbiology.


PubMed | Batelle Memorial Institute and National Homeland Security Research Center
Type: Journal Article | Journal: Letters in applied microbiology | Year: 2015

Five commercially available liquid antimicrobials were evaluated for their ability to decontaminate common environmental surface materials, contaminated with Burkholderia pseudomallei, using a spray-based disinfectant delivery procedure. Tests were conducted at both an ambient temperature (c. 20C) and a lower temperature (c. 12C) condition. Nonporous materials (glass and aluminium) were more easily decontaminated than porous materials (wood, concrete and carpet). Citric acid (1%) demonstrated poor efficacy in all test conditions. Bleach (pH-adjusted), ethanol (70%), quaternary ammonium and PineSol, demonstrated high (>6 log10 reduction) efficacies on glass and aluminium at both temperatures, but achieved varying results for wood, carpet and concrete. Temperature had minimal effect on decontamination efficacy during these tests.Much of the antimicrobial efficacy data for pathogenic micro-organisms are generated with testing that utilizes hard nonporous surface materials. These data are not directly translatable for decontaminant selection following an incident whereby complex and porous environmental surfaces are contaminated. This study presents efficacy data for spray-applied antimicrobial liquids, when used to decontaminate common environmental surfaces contaminated with Burkholderia pseudomallei. These data can help responders develop effective remediation strategies following an environmental contamination incident involving B. pseudomallei.


Meyer K.M.,Oak Ridge Institute for Science and Education | Tufts J.A.,Oak Ridge Institute for Science and Education | Calfee M.W.,National Homeland Security Research Center | Oudejans L.,National Homeland Security Research Center
Journal of Applied Microbiology | Year: 2014

Aims: To evaluate five commercially available sporicidal wipes and two disinfecting wipes for their ability to inactivate Bacillus atrophaeus spores deposited onto various material surfaces. Methods and Results: Decontamination efficacy of the wipes was initially tested on glass Petri dishes (150 mm diameter). Following exposure for a specified time of contact, survival of the spores was assessed by quantification of the remaining viable spores, both on the coupon surface and on the towelette itself, with efficacy quantified in terms of mean log reduction. Based on these data, five wipes were down-selected for evaluation on a larger scale, using 36 × 36 cm coupons of five different material types. Conclusions: Results suggest that sodium hypochlorite-based sporicidal wipes were most effective, having completely inactivated the Bacillus spores on the glass Petri dish and several materials. Additionally, results demonstrate that the manufacturer-prescribed contact times for Clostridium difficile achieved a 6 log10 reduction of B. atrophaeus spores. Moreover, commercially available disinfecting wipes were not able to kill Bacillus spores as evaluated. Significance and Impact of the Study: These data show the potential of sporicidal wipes for decontamination of small, contained areas of biological contamination and may help on-scene coordinators develop remediation plans following a biological terrorism event. © 2014 The Society for Applied Microbiology.


Tufts J.A.M.,Oak Ridge Institute for Science and Education | Tufts J.A.M.,National Homeland Security Research Center | Calfee M.W.,National Homeland Security Research Center | Lee S.D.,National Homeland Security Research Center | Ryan S.P.,National Homeland Security Research Center
World Journal of Microbiology and Biotechnology | Year: 2014

Characterization of candidate surrogate spores prior to experimental use is critical to confirm that the surrogate characteristics are as closely similar as possible to those of the pathogenic agent of interest. This review compares the physical properties inherent to spores of Bacillus anthracis (Ba) and Bacillus thuringiensis (Bt) that impact their movement in air and interaction with surfaces, including size, shape, density, surface morphology, structure and hydrophobicity. Also evaluated is the impact of irradiation on the physical properties of both Bacillus species. Many physical features of Bt and Ba have been found to be similar and, while Bt is considered typically non-pathogenic, it is in the B. cereus group, as is Ba. When cultured and sporulated under similar conditions, both microorganisms share a similar cylindrical pellet shape, an aerodynamic diameter of approximately 1 μm (in the respirable size range), have an exosporium with a hairy nap, and have higher relative hydrophobicities than other Bacillus species. While spore size, morphology, and other physical properties can vary among strains of the same species, the variations can be due to growth/sporulation conditions and may, therefore, be controlled. Growth and sporulation conditions are likely among the most important factors that influence the representativeness of one species, or preparation, to another. All Bt spores may, therefore, not be representative of all Ba spores. Irradiated spores do not appear to be a good surrogate to predict the behavior of non-irradiated spores due to structural damage caused by the irradiation. While the use of Bt as a surrogate for Ba in aerosol testing appears to be well supported, this review does not attempt to narrow selection between Bt strains. Comparative studies should be performed to test the hypothesis that viable Ba and Bt spores will behave similarly when suspended in the air (as an aerosol) and to compare the known microscale characteristics versus the macroscale response. © 2013 Springer Science+Business Media Dordrecht (ouside the USA).


Hart W.E.,Sandia National Laboratories | Murray R.,National Homeland Security Research Center
Journal of Water Resources Planning and Management | Year: 2010

Contamination warning systems (CWSs) are a promising approach for the mitigation of contamination risks in drinking water distribution systems. A critical aspect of the design of a CWS is the strategic placement of online sensors that rapidly detect contaminants. This paper reviews the array of optimization-based sensor placement strategies that have been recently proposed. These strategies are critiqued and several key issues are identified that need to be addressed in future work. © 2010 ASCE.


Seth A.,Purdue University | Klise K.A.,Sandia National Laboratories | Siirola J.D.,Sandia National Laboratories | Haxton T.,National Homeland Security Research Center | Laird C.D.,Purdue University
Journal of Water Resources Planning and Management | Year: 2016

In the event of contamination in a water distribution network (WDN), source identification (SI) methods that analyze sensor data can be used to identify the source location(s). Knowledge of the source location and characteristics are important to inform contamination control and cleanup operations. Various SI strategies that have been developed by researchers differ in their underlying assumptions and solution techniques. The following manuscript presents a systematic procedure for testing and evaluating SI methods. The performance of these SI methods is affected by various factors including the size of WDN model, measurement error, modeling error, time and number of contaminant injections, and time and number of measurements. This paper includes test cases that vary these factors and evaluates three SI methods on the basis of accuracy and specificity. The tests are used to review and compare these different SI methods, highlighting their strengths in handling various identification scenarios. These SI methods and a testing framework that includes the test cases and analysis tools presented in this paper have been integrated into EPA's Water Security Toolkit (WST), a suite of software tools to help researchers and others in the water industry evaluate and plan various response strategies in case of a contamination incident. Finally, a set of recommendations are made for users to consider when working with different categories of SI methods. © 2016 American Society of Civil Engineers.


Hosni A.A.,University of Cincinnati | Szabo J.G.,National Homeland Security Research Center | Bishop P.L.,University of Cincinnati
Journal of Environmental Engineering | Year: 2011

This paper presents results describing the effectiveness of chlorine dioxide penetration into a drinking-water distribution system biofilm/corrosion matrix and decontamination of adhered Bacillus globigii spores, a surrogate for Bacillus anthracis. Biofilm and corrosion products were developed using biofilm annular reactors containing oxidized scaled, iron coupons. Reactors were inoculated with B. globigii spores after biofilm development, and decontamination was undertaken with bulk-phase chlorine dioxide concentrations of 5, 10, 15, and 25 mg/L. Initial biofilm viable B. globigii spore densities of 10 6 CFU/cm 2 were reduced to 50 to 300 CFU/cm 2 at chlorine dioxide concentrations of 25 and 15 mg/L, respectively, within 6days. B. globigii spore distribution throughout the biofilm/corrosion matrix depth and the change in viable spore count during chlorine dioxide disinfection were examined using a microslicing technique. Four layers of 360μm thickness were sliced, and these showed that B. globigii spores were equally distributed throughout the biofilm/corrosion matrix depth. Furthermore, chlorine dioxide acted on all layers simultaneously, but spores still persisted in the deepest layer of the biofilm/corrosion matrix after 6days of disinfection at 15 and 25 mg/L chlorine dioxide. © 2011 American Society of Civil Engineers.


Calfee M.W.,National Homeland Security Research Center | Lee S.D.,National Homeland Security Research Center | Ryan S.P.,National Homeland Security Research Center
Journal of Microbiological Methods | Year: 2013

A simple method for repeatably inoculating surfaces with a precise quantity of aerosolized spores was developed. Laboratory studies were conducted to evaluate the variability of the method within and between experiments, the spatial distribution of spore deposition, the applicability of the method to complex surface types, and the relationship between material surface roughness and spore recoveries. Surface concentrations, as estimated by recoveries from wetted-wipe sampling, were between 5×103 and 1.5×104CFUcm-2 across the entire area (930cm2) inoculated. Between-test variability (Cv) in spore recoveries was 40%, 81%, 66%, and 20% for stainless steel, concrete, wood, and drywall, respectively. Within-test variability was lower, and did not exceed 33%, 47%, 52%, and 20% for these materials. The data demonstrate that this method is repeatable, is effective at depositing spores across a target surface area, and can be used to dose complex materials such as concrete, wood, and drywall. In addition, the data demonstrate that surface sampling recoveries vary by material type, and this variability can partially be explained by the material surface roughness index. This deposition method was developed for use in biological agent detection, sampling, and decontamination studies, however, is potentially beneficial to any scientific discipline that investigates surfaces containing aerosol-borne particles. © 2013.

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