Depleted uranium (DU) is uranium that has a reduced proportion of the isotope Uranium-235 and is mostly comprised of Uranium-238. It is primarily used for military applications such as projectile munitions and tank armor. Its use remains highly controversial. In addition to its residual radioactivity (DU has a half-life of 4.5 billion, with a "b", years), U-238 is known from several laboratory studies to be toxic to mammals, especially to the reproductive system and fetus development, causing reduced fertility, miscarriages and fetus malformations.

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