Uranium and Human Health Alpha particles are produced during the disintegration of uranium. Because the skin blocks the alpha particles, external exposure to uranium is less harmful than exposure to other radioactive elements. Ingestion of excessive uranium concentrations can result in health problems such as bone or liver cancer. Uranium is also toxic to humans through inhalation or ingestion of its dust or water contamination. The lungs and gastrointestinal system are most likely to be affected by excessive uranium levels. Alpha particles are helium atoms emitted when uranium decays. They have no mass and travel at the speed of light. They are able to penetrate deep into human tissue before decaying into a more stable state. This allows uranium to be used as a source of ionizing radiation for medical imaging and therapy. It also makes it dangerous if you try to use it for making bombs; even if you use very pure uranium, it still produces alpha particles when it decays, which could damage anything they touch. Uranium is a natural element that exists in three main forms: uranium ore, uranium fuel, and uranium waste. Natural uranium occurs in several minerals including uraninite, carnotite, and lepidocrocite. Some sources claim that there is more uranium found in seawater than in all the uranium ore on Earth. However, most of this natural uranium is so chemically unspecialized that it cannot be used for any practical purpose.