The BIER IV Committee of the National Academy of Sciences, National Research Council, found that "there is little convincing epidemiological evidence that serious renal disease has occurred in human populations as a result of chronic low-level exposure nor of increased rates of malignant tumors." [Sullivan, p. 1272] Uranium causes acute tubular necrosis in animal experiments, but the case for kidney disease in humans after chronic occupational exposure is unclear. [LaDou, p. 422] Acute renal failure in humans has been reported rarely. No chronic renal disease has been documented. [Rosenstock, p. 574] Studies of uranium and other underground miners in the 1950s showed increased rates of lung cancer in workers heavily exposed to radon decay products. [Rosenstock, p. 732] Absorption through intact skin may occur: Uranyl nitrate; uranyl fluoride; uranium pentachloride; uranium trioxide (uranyl oxide); and uranium hexafluoride; Urine concentrations are less than 0.02 ug/24 hours as background and 100 ug/L in workers exposed to at least 50 ug/cu m; [HSDB] "The toxicity of uranium varies according to its chemical form and route of exposure. On the basis of the toxicity of different uranium compounds in animals, it was concluded that the relatively more water-soluble compounds (uranyl nitrate hexahydrate, uranium hexafluoride, uranyl fluoride, uranium tetrachloride, uranium pentachloride) were the most potent renal toxicants." [ATSDR ToxProfiles] "Fourteen epidemiologic studies have been conducted of more than 120,000 workers at uranium processing, enriching, metal fabrication, and milling facilities. These studies overall found no cancer to be significantly increased." [Boice, p. 274] "Our results support previous estimates that the depleted uranium levels inhaled during the 1991 friendly fire incidents likely do not cause long-term adverse pulmonary health effects." [
PMID 23887699]
Most Important Radionuclide: U-238
Source: Mined from natural deposits (99.3% U-238)
Half-Life: 4.5 billion years
Specific Activity: 0.00000034 Ci/gm
Decay Mode: Alpha, Spontaneous Fission
GI Absorption: 0.2% to 5%
Lung Clearance Half-Time: Days for UF6, UO2F2, and UO2(NO3)2; Weeks for UO3, UF4, and UCl4; Years for UO2 and U3O8;
Critical Organ: Kidney
Internal Toxicity: Very High
Annual Limit on Intake: 0.00004 mCi
Radiation Energy (MeV): Alpha 4.2 (75%); Alpha 4.15 (25%) + daughters;
Radiation Accidents: 1 accident involving 1 person exposed to U-235; 1 incident of "Meltings of Radioactive Materials"; [See Glossary for references.] See "Radiation, ionizing."