Uranium is a naturally occurring weakly radioactive element. High levels of uranium in water may increase the risk of cancer and kidney damage. Most of the uranium that is ingested by food or drink by the human body is excreted, but some amounts are absorbed into the bloodstream and kidneys. The health effects from ingesting uranium are caused primarily by chemical damage, not by the radioactivity. Uranium decreases the kidneys’ ability to filter toxins from the bloodstream. These effects are reversible if the uranium contamination is eliminated.