Christy A Emond

Uniformed Services University of the Health Sciences, Maryland, United States

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Publications (7)20.81 Total impact

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    Christy A Emond, John F Kalinich
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    ABSTRACT: The terrorist use of a radiological dispersal device (RDD) has been described as "not if, but when" (). Exposures from such an event could occur by a number of routes including inhalation, wound contamination, or embedded fragments. Several of the radionuclides thought to be potential RDD components are metals or ceramic material. The use of such material would increase the potential for wounds from embedded fragments of radioactive material. To date, most research in this area has focused on inhalation exposures, while the consequence of embedded fragment exposure has not been investigated. This study modified a previously used rodent model in order to determine the biokinetics of intramuscularly implanted nonradioactive surrogate RDD material. Cobalt, iridium, or strontium titanate was embedded into the gastrocnemius muscle of Sprague Dawley rats. The rats were euthanized at 1, 3, or 6 mo post-implantation. Tissue metal analysis showed that iridium did not solubilize from the implanted pellet, while cobalt and strontium did so rapidly. Cobalt was found in all tissues analyzed, but it was localized mainly to kidney and liver as well as being excreted in the urine. Strontium was found in lung, liver, and spleen, as well as being deposited in bone. However, the greatest strontium concentrations were found in the popliteal lymph nodes, the lymph nodes responsible for draining the area of the gastrocnemius. These results indicate that, depending upon the material, a variety of treatment strategies will be needed when dealing with embedded fragment wounds from a radiological dispersal device event.
    Health physics 02/2012; 102(2):124-36. · 0.92 Impact Factor
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    ABSTRACT: Novel metal formulations are being used with increasing frequency on the modern battlefield. In many cases the health effects of these materials are not known, especially when they are embedded as fragments. Imaging techniques, although useful for determining location, provide no information regarding the composition of embedded fragments. In this report, we show that laboratory rats implanted with weapons-grade tungsten alloy (tungsten, nickel, and cobalt) pellets demonstrate significant increases in both urinary and serum levels of tungsten, nickel, and cobalt, which indicates that such measurements can provide information on the composition of embedded fragments. We also propose that, in addition to the requirements promulgated by the recent directive on analysis of metal fragments removed from Department of Defense personnel (Health Affairs policy 07-029), urine and blood/serum samples should be collected from personnel and analyzed for metal content. Such measurements could yield information on the composition of retained fragments and provide the basis for further treatment options.
    Military medicine 09/2008; 173(8):754-8. · 0.77 Impact Factor
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    ABSTRACT: Continuing concern regarding the potential health and environmental effects of depleted uranium and lead has resulted in many countries adding tungsten alloy (WA)-based munitions to their battlefield arsenals as replacements for these metals. Because the alloys used in many munitions are relatively recent additions to the list of militarily relevant metals, very little is known about the health effects of these metals after internalization as embedded shrapnel. Previous work in this laboratory developed a rodent model system that mimicked shrapnel loads seen in wounded personnel from the 1991 Persian Gulf War. In the present study, we used that system and male F344 rats, implanted intramuscularly with pellets (1 mm times 2 mm cylinders) of weapons-grade WA, to simulate shrapnel wounds. Rats were implanted with 4 (low dose) or 20 pellets (high dose) of WA. Tantalum (20 pellets) and nickel (20 pellets) served as negative and positive controls, respectively. The high-dose WA-implanted rats (n = 46) developed extremely aggressive tumors surrounding the pellets within 4-5 months after implantation. The low-dose WA-implanted rats (n = 46) and nickel-implanted rats (n = 36) also developed tumors surrounding the pellets but at a slower rate. Rats implanted with tantalum (n = 46), an inert control metal, did not develop tumors. Tumor yield was 100% in both the low- and high-dose WA groups. The tumors, characterized as high-grade pleomorphic rhabdomyosarcomas by histopathology and immunohistochemical examination, rapidly metastasized to the lung and necessitated euthanasia of the animal. Significant hematologic changes, indicative of polycythemia, were also observed in the high-dose WA-implanted rats. These changes were apparent as early as 1 month postimplantation in the high-dose WA rats, well before any overt signs of tumor development. These results point out the need for further studies investigating the health effects of tungsten and tungsten-based alloys.
    Environmental Health Perspectives 07/2005; 113(6):729-34. · 7.26 Impact Factor
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    ABSTRACT: The health effects of embedded fragments of depleted uranium (DU) are being investigated to determine whether current surgical fragment-removal policies are appropriate for this metal. The authors studied rodents implanted with DU pellets as well as cultured human cells exposed to DU compounds. Results indicate that uranium from implanted DU fragments distributes to tissues distant from implantation sites, including bone, kidney, muscle, and liver. Despite levels of uranium in kidney that would be nephrotoxic after acute exposure, no histological or functional kidney toxicity was observed with embedded DU, indicating that the kidney adapts when exposed chronically. Nonetheless, further studies of the long-term health impact are needed. DU is mutagenic and transforms human osteoblastic cells into a tumorigenic phenotype. It alters neurophysiological parameters in rat hippocampus, crosses the placental barrier, and enters fetal tissue. Preliminary data also indicate decreased rodent litter size when animals are bred 6 months or longer after DU implantation.
    Military medicine 03/2002; 167(2 Suppl):117-9. · 0.77 Impact Factor
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    ABSTRACT: The Persian Gulf War resulted in injuries of US Coalition personnel by fragments of depleted uranium (DU). Fragments not immediately threatening the health of the individuals were allowed to remain in place, based on long-standing treatment protocols designed for other kinds of metal shrapnel injuries. However, questions were soon raised as to whether this approach is appropriate for a metal with the unique radiological and toxicological properties of DU. The Armed Forces Radiobiology Research Institute (AFRRI) is investigating health effects of embedded fragments of DU to determine whether current surgical fragment removal policies remain appropriate for this metal. These studies employ rodents implanted with DU pellets as well as cultured human cells exposed to DU compounds. Results indicate uranium from implanted DU fragments distributed to tissues far-removed from implantation sites, including bone, kidney, muscle, and liver. Despite levels of uranium in the kidney that were nephrotoxic after acute exposure, no histological or functional kidney toxicity was observed. However, results suggest the need for further studies of long-term health impact, since DU was found to be mutagenic, and it transformed human osteoblast cells to a tumorigenic phenotype. It also altered neurophysiological parameters in rat hippocampus, crossed the placental barrier, and entered fetal tissue. This report summarizes AFRRI's depleted uranium research to date.
    Science of The Total Environment 08/2001; 274(1-3):115-8. · 3.26 Impact Factor
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    ABSTRACT: During the Persian Gulf War, soldiers were injured with depleted uranium (DU) fragments. To assess the potential health risks associated with chronic exposure to DU, Sprague Dawley rats were surgically implanted with DU pellets at 3 dose levels (low, medium and high). Biologically inert tantalum (Ta) pellets were used as controls. At 1 day and 6, 12, and 18 months after implantation, the rats were euthanized and tissue samples collected. Using kinetic phosphorimetry, uranium levels were measured. As early as 1 day after pellet implantation and at all subsequent sample times, the greatest concentrations of uranium were in the kidney and tibia. At all time points, uranium concentrations in kidney and bone (tibia and skull) were significantly greater in the high-dose rats than in the Ta-control group. By 18 months post-implantation, the uranium concentration in kidney and bone of low-dose animals was significantly different from that in the Ta controls. Significant concentrations of uranium were excreted in the urine throughout the 18 months of the study (224 +/- 32 ng U/ml urine in low-dose rats and 1010 +/- 87 ng U/ml urine in high-dose rats at 12 months). Many other tissues (muscle, spleen, liver, heart, lung, brain, lymph nodes, and testicles) contained significant concentrations of uranium in the implanted animals. From these results, we conclude that kidney and bone are the primary reservoirs for uranium redistributed from intramuscularly embedded fragments. The accumulations in brain, lymph nodes, and testicles suggest the potential for unanticipated physiological consequences of exposure to uranium through this route.
    Toxicological Sciences 06/1999; 49(1):29-39. · 4.33 Impact Factor
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    ABSTRACT: During the 1991 Persian Gulf War several US military personnel were wounded by shrapnel fragments consisting of depleted uranium. These fragments were treated as conventional shrapnel and were not surgically removed to spare excessive tissue damage. Uranium bioassays conducted over a year after the initial uranium injury indicated a significant increase in urine uranium levels above natural background levels. The potential mutagenic effects of depleted uranium are unknown. To assess the potential mutagenic effects of long-term exposure to internalized depleted uranium, Sprague-Dawley rats were implanted with depleted uranium and their urine and serum were evaluated for mutagenic potential at various times after pellet implantation using the Ames Salmonella reversion assay. Tantalum, an inert metal widely used in prosthetic devices was used for comparison. Enhancement of mutagenic activity in Salmonella typhimurium strain TA98 and the Ames II mixed strains (TA7001-7006) was observed in urine samples from animals implanted with depleted uranium pellets. In contrast, urine samples from animals implanted with tantalum did not show a significant enhancement of mutagenic activity in these strains. In depleted uranium-implanted animals, urine mutagenicity increased in a dose- and time-dependent manner demonstrating a strong positive correlation with urine uranium levels (r = 0.995, P < 0.001). There was no mutagenic enhancement of any bacterial strain detected in the sera of animals implanted with either depleted uranium or tantalum pellets. The results suggest that uranium content in the urine is correlated with urine mutagenicity and that urinary mutagenicity might be used as a biomarker to detect exposure to internalized uranium.
    Mutagenesis 12/1998; 13(6):643-8. · 3.50 Impact Factor