A person can be exposed to uranium by inhaling dust in air, or ingesting water and food. The general population is exposed to uranium primarily through food and water. The average daily intake of uranium from food ranges from 0.07 to 1.1 micrograms per day. The amount of uranium in air is usually very small. People who live near federal government facilities that made or tested nuclear weapons, or facilities that mine or process uranium ore or enrich uranium for reactor fuel, may have increased exposure to uranium.
Uranium can enter the body when it is inhaled or swallowed, or under rare circumstances it may enter through cuts in the skin. Uranium does not absorb through the skin, and alpha particles released by uranium cannot penetrate the skin, so uranium that is outside the body is much less harmful than it would be if it where inhaled or swallowed. When uranium gets inside the body it can lead to cancer or kidney damage.
About 99 percent of the uranium ingested in food or water will leave a person's body in the feces, and the remainder will enter the blood. Most of this absorbed uranium will be removed by the kidneys and excreted in the urine within a few days. A small amount of the uranium in the bloodstream will deposit in a person's bones, where it will remain for years.