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SummaryArmor-piercing, depleted-uranium (DU) munitions were used by the U.S. Armed Forces on the battlefield for the first time during the 1991 Gulf War Operation Desert Storm (ODS).( ) a Although the U.S. Army has conducted periodic impact tests on armored targets, the tests involved only limited sampling to characterize the aerosols that form when DU penetrators impact and perforate targets. As a consequence, the available data were insufficient for performing human health risk assessments. To remedy this, the U.S. Department of Defense (DoD) committed to obtaining more complete data about aerosols generated by the impact and perforation of armored vehicles by DU munitions to support a revised and updated personnel exposure assessment and human health risk characterization. The program arising from this commitment is the Capstone DU Aerosol Characterization and Risk Assessment Program consisting of two separate components. The first is the Capstone DU Aerosol Study, in which DU aerosols were generated through perforation of armored target vehicles, and the chemical and physical properties of aerosols generated were characterized. The study methods and results are presented in this report. The second component of the program is the Human Health Risk Assessment, documented in the Human Health Risk Assessment of Capstone Depleted Uranium Aerosols (Guilmette et al. 2004). S.1 PurposeUnder a program jointly sponsored by the Office of the Special Assistant for Gulf War Illnesses, Medical Readiness and Military Deployment (OSAGWI) ( ) b and the U.S. Army, the Army Heavy Metals Office provided oversight to the Capstone DU Aerosol Study, which was designed to quantify and characterize DU aerosols inside, on, and near Abrams tanks and Bradley Fighting Vehicles (also referred to as Bradley vehicles) struck by large-caliber DU (LC-DU) penetrators. This report, which documents the Capstone study, is the sourcebook of data from which reasonable and appropriate data could be selected for assessing exposure and characterizing human health risks to personnel who were exposed to aerosols during the Gulf War/ODS or potentially could be exposed to aerosols in future military activities. These data are expected to fill many gaps in available aerosol knowledge, thereby helping risk assessors to better estimate the health risks from DU aerosols to affected personnel.The aerosol data derived from this study provides the basis for modeling input parameters by summarizing the bounds and characteristics of typical aerosols generated by perforating armored vehicles with LC-DU penetrators. The test results will be used to update the human health risk characterizations for OSAGWI Gulf War/ODS exposure scenarios, and to determine if changes in personnel protective measures are warranted to reduce risks to DoD personnel in the future. S.2 Investigation TeamAn independent subject matter expert from Pacific Northwest National Laboratory (PNNL) directed the Capstone DU Aerosol Study. S.3 Study OverviewThe Capstone DU Aerosol Study involved ...

Recent epidemiologic investigations of the relationship between residential radon gas exposure and lung cancer relied on contemporary radon gas measurements to estimate past radon gas exposures. Significant uncertainties in these exposure estimates can arise from year-to-year variation of indoor radon concentrations and subject mobility. Surface implanted 210Po has shown potential for improving retrospective radon gas exposure estimates. However, in previous studies, the ability of implanted 210Po activity to reconstruct cumulative radon gas exposure was not tested because glass was not available from homes with known radon-gas concentration histories. In this study, we tested the validity of the retrospective radon gas reconstruction using implanted 210Po surface activity by measuring glass surfaces from homes whose annual-average radon gas concentrations had been measured almost every year during two decades. Regression analysis showed a higher correlation between measured surface activity and cumulative radon gas exposure in these homes (R2>0.8) than was observed in homes where only contemporary radon gas measurements were available. The regression slope (0.57 ky m(-1)) was consistent with our earlier retrospective results. Surface activity measurements were as reliable for retrospective radon gas exposure reconstruction as yearlong gas measurements. Both methods produced estimates that were within 25% of the long-term average radon gas concentrations in a home. Surface measurements can be used for home screening tests because they can provide rapid, reliable estimates of past radon gas concentrations. Implanted 210Po measurements are also useful in retrospective epidemiologic studies that include participants who may have been exposed to highly variable radon concentrations in previously occupied or structurally modified homes.