Uranium is a naturally-occurring element that is one of the hardest and densest metals known. Because it is found everywhere on earth, we eat and breathe a small amount every day. People have been mining uranium and using it commercially for over 60 years, so there is a great deal of information available on this metal. The Toxicological Profile for Uranium contains a complete description of the metal, and its known health hazards.

Natural uranium becomes depleted uranium (DU) after most of a more radioactive isotope is removed for nuclear fuel production. DU is a heavy metal that is almost twice as dense as lead, having the same chemical properties as natural uranium, but 40 percent less radioactivity.

DoD began testing DU about 40 years ago, and first used it in a military operation in 1991. It has fewer risks than natural uranium because it is less radioactive. DoD and many other organizations have studied, and continue to study, the health, chemical, radiological and environmental effects and exposures of DU.