Uranium, a naturally occurring element that is very dense and heavy, is mildly radioactive and toxic, with a half-life of 4.5 billion years. The greatest health risk from large intakes of uranium is toxic damage to the kidneys.
Uranium-238 is used to produce plutonium-239, which was the primary mission at the Hanford Nuclear Site in Washington State. The U.S. Department of Energy (USDOE) only considered the radioactivity of uranium, not its toxicity, in its modeling. Uranium-238 is a primary groundwater contaminant in the 300 Area at Hanford.
