W2-C
Exposure from chemical weapons and unmonitored releasesFederal Hill 1:30 PM
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| Chair(s): Susan Flack sflack@chemrisk.com
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| This session discusses exposure from chemical weapons and unmonitored releases. It includes presentations related to assessing exposure of unmonitored plutonium releases during WWII and from the first plutonium component production facility, and risks of land contaminated with unexploded ordnance. |
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W2-C.1 1:30 PM Modeling exposure and risk from chemical weapons releases. Chrostowski PC*, Foster SA; CPF Associates, Inc. pc@cpfassociates.com
Abstract: Emergency planners and first responders often need to rapidly and accurately evaluate the release of chemical warfare agents from a variety of delivery systems. Although several mathematical models are commercially available and used by stakeholders to evaluate exposures and risks associated with chemical emergencies, chemical weapons present special modeling challenges. Models with built-in chemical data bases may lack adequate information concerning physicochemical or toxicological properties of chemical weapons. Source characterizations in commercially available models may be oriented toward the chemical industry or exposure of the general public rather than a purposefully targeted population -- for example, a release associated with a runaway reaction in a chemical reactor or an explosion stemming from a petroleum transportation accident rather than an improvised explosive device. The military has developed additional models that are specifically oriented to assessment of chemical weapons discharges, however, these are limited in geographical scope and chemical inclusion and most first responders are unfamiliar with their use. This paper presents the first results of a project where we compare the operation of an US EPA/FEMA model (Aloha/Cameo) to a US Army model (D2PC) for assessing exposure and risks of an obsolete chemical weapon, Lewisite, to the general public. The presentation will discuss parameterization of the models, utility to first responders and planners,and show a comparison of outputs of the models when a variety of release scenarios is simulated. Recommendations are made for use of the models under field conditions.
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W2-C.2 1:50 PM An exposure assessment reflecting unmonitored plutonium releases during WWII and supported by a unique dataset of historical human tissue analyses. Shonka JJ, Donovan EP*, Flack SM, Widner TE; Shonka Research Associates, ChemRisk, Inc. edonovan@chemrisk.com
Abstract: US production of plutonium (Pu) parts for the first atomic bombs was performed in Los Alamos, NM facilities that were primitive by modern standards. Airborne effluents left the first production building via numerous roof-top vents that were unmonitored and largely unfiltered. The lack of monitoring data hampers efforts to retrospectively assess exposures to residents, who lived as close as 200 m away. A historical dataset, rarely available for assessments of this type, was used to address the data gap. Starting in 1959, human tissue samples were taken during autopsy from adults who lived in Los Alamos as early as 1944. Tissue concentrations obtained from published reports of Los Alamos Scientific Laboratory's tissue analysis program (with donor identities and specific locations of residence withheld) were evaluated as indicators of historical Pu releases. Data from autopsies of 97 non-worker residents are available, as are data from 60 Pu workers. Independent searching of the Laboratory Archives in early 2006 by a team from CDC's Los Alamos Historical Document Retrieval and Assessment project yielded extensive documentation of the autopsy cases that had been lacking, including address at time of death and years at that residence. Additional data from the local cemetery, newspaper, and telephone books were used to establish a residence history for each tissue donor. Ratios of Pu levels in lung, vertebrae, and liver were examined as indicators of residence time in the body. The range and bearing of each residence relative to Pu processing buildings were calculated, and analyses performed to address the potential magnitude of public exposures from Los Alamos Pu processing and reduce the uncertainty of dose reconstruction. The data indicate that excess Pu is present in non-worker residents over what would be expected from global weapons testing fallout, and the Pu appears to be from exposures that occurred before large-scale atmospheric weapons testing.
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W2-C.3 2:10 PM Assessing risks of land contaminated with unexploded ordnance. MacDonald JA*; Carnegie Mellon University jmacdona@andrew.cmu.edu
Abstract: This talk will describe a new, probabilistic model for quantifying the risks of civilian casualties on land that is contaminated with unexploded ordnance (UXO). UXO is present not only in former battle areas around the world, but also is an increasing problem in the United States due to the conversion of former military bases to civilian uses. UXO is present wherever the US military has conducted live-fire training. An estimated 40,000 km2 of land in the United States are affected. Total cleanup cost estimates range from $8-140 billion. Previous efforts to assess risks of reusing these sites have not produced probabilistic risk estimates and thus have had limited utility as decision-support tools. The model presented in this talk is the first to quantify UXO explosion risks in probabilistic terms. The model has three components. Each component can be tailored to the individual site to different degrees depending on data availability. The first component describes the three-dimensional spatial distribution of UXO. For any given land-use scenario, this component gives the probability distribution for the number of UXO encountered. The probability distribution is based on fitting of spatial statistical models to UXO location data at selected areas that have been extensively searched. The second component describes the probability that UXO will be detected during cleanup in advance of land reuse. This model component is based on field tests of UXO detection probabilities for metal detectors. The third component describes the probability that a UXO item will explode if handled. This model component is based on elicitation of probability distributions from explosive ordnance disposal experts. We have demonstrated the model using data from a closed Army base. The talk will describe our findings from the demonstration at this base, including the estimated cost per avoided exposure to UXO and avoided UXO explosion for different cleanup options.
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W2-C.4 2:30 PM Exposure assessment approaches for unmonitored releases from the world's first plutonium component production facility: Los Alamos, NM (1944-1945). Widner TE, Knutsen JS, Flack SM*; ChemRisk, Inc. sflack@chemrisk.com
Abstract: Constructed in 1943, D Building in Los Alamos was the first facility in the world to process gram and then kilogram quantities of plutonium to manufacture atomic bomb parts. As increasing quantities of the new and largely unknown plutonium were received from Oak Ridge and Hanford, purification, conversion to metal, and component fabrication were scaled up to ultimately produce the Trinity device and the Fat Man bomb. A state-of-the-art air conditioning system, provided to keep dust away from the rare plutonium, was not as well suited to contain airborne contamination in the heavily contaminated building. Effluents via numerous roof-top vents were unmonitored and largely unfiltered. Official compilations of Los Alamos effluents have reflected no contribution from D Building. CDC's Los Alamos Historical Document Retrieval and Assessment project team has studied D Building to support bounding of plutonium releases from the facility and allow assessment of exposures to Los Alamos residents, who lived as close as 200 m away. Documents, photographs, and drawings were reviewed, and workers with D-Building experience were interviewed to fill in information gaps. The equipment and processes that were used in D Building were characterized, as were the quantities of plutonium processed and indoor and environmental concentrations. Plutonium processing was subdivided into a series of operations, including solution chemistry (e.g., decanting, filtering, and boiling), dry chemistry (e.g., weighing, filling, and metallothermic reductions), and metallurgical work (e.g., alloying, machining, and pressing). To support prioritization of potential public exposures from wartime activities in D Building, potential releases from each operation were estimated by applying relevant heuristics from US NRC and DOE-sponsored experimental programs concerning release fractions and respirable fractions for nonreactor nuclear facilities.
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