Depleted uranium

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Depleted uranium (DU) is uranium primarily composed of the isotope uranium-238 (U-238). Natural uranium is about 99.27 percent U-238, 0.72 percent U-235, and 0.0055 percent U-234. U-235 is used for fission in nuclear reactors and nuclear weapons. Uranium is enriched in U-235 by separating the isotopes by mass. The byproduct of enrichment, called depleted uranium or DU, contains less than one third as much U-235 and U-234 as natural uranium. The external radiation dose from DU is about 60 percent of that from the same mass of natural uranium.[2] DU is also found in reprocessed spent nuclear reactor fuel, but that kind can be distinguished from DU produced as a byproduct of uranium enrichment by the presence of U-236.[3] In the past, DU has been called Q-metal, depletalloy, and D-38.

DU is useful because of its very high density of 19.1 g/cm3 (68.4% denser than lead). Civilian uses include counterweights in aircraft, radiation shielding in medical radiation therapy and industrial radiography equipment, and containers used to transport radioactive materials. Military uses include defensive armor plating and armor-piercing projectiles.

The use of DU in munitions is controversial because of questions about potential long-term health effects.[4][5] Normal functioning of the kidney, brain, liver, heart, and numerous other systems can be affected by uranium exposure, because uranium is a toxic metal.[6] It is weakly radioactive and remains so because of its long physical half-life (4.468 billion years for uranium-238). The biological half-life (the average time it takes for the human body to eliminate half the amount in the body) for uranium is about 15 days.[7] The aerosol produced during impact and combustion of depleted uranium munitions can potentially contaminate wide areas around the impact sites leading to possible inhalation by human beings.[8] During a three week period of conflict in 2003 in Iraq, 1,000 to 2,000 tonnes of DU munitions were used.[9]

The actual acute and chronic toxicity of DU is also a point of medical controversy. Multiple studies using cultured cells and laboratory rodents suggest the possibility of leukemogenic, genetic, reproductive, and neurological effects from chronic exposure.[4] A 2005 epidemiology review concluded: "In aggregate the human epidemiological evidence is consistent with increased risk of birth defects in offspring of persons exposed to DU."[10] The World Health Organization, the directing and coordinating authority for health within the United Nations which is responsible for setting health research norms and standards, providing technical support to countries and monitoring and assessing health trends,[11] states that no risk of reproductive, developmental, or carcinogenic effects have been reported in humans due to DU exposure.[12][13] This report has been criticized by Dr. Keith Baverstock for not including possible long term effects of DU on human body.[14]

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