Uranium

Uranium is the heaviest naturally occurring element and is present in trace amounts in virtually all rocks and soils, with concentrations elevated in granites, phosphate deposits, and black shales [1]. Weathering and dissolution from uranium-bearing formations leaches uranium into groundwater — a natural process that has made certain aquifers, particularly in the western United States, the Great Plains, and the Southeast, chronically uranium-elevated [2]. Human activities add uranium through phosphate fertilizer application (phosphate rock contains significant uranium), uranium mining and milling operations, and nuclear facility releases. EPA's MCL for uranium in drinking water is 30 µg/L [1]. Medical and industrial uses of depleted uranium (DU) in armor-piercing munitions and radiation shielding have created localized contamination at military testing ranges and exposed veterans during the Gulf War [2].

Private wells in uranium-bearing geology are the primary dietary route for affected populations [1]. Municipal water supplies are monitored under SDWA and treated if uranium exceeds 30 µg/L. Phosphate-fertilized agricultural soils can elevate uranium in root vegetables and grains [2]. Occupational exposure occurs in uranium mining, milling, fuel fabrication, and military settings using depleted uranium [1]. Inhalation of uranium-containing dust at contaminated sites is possible but dietary/water intake is dominant for the general population [2].

At the concentrations found in contaminated drinking water, uranium's chemical kidney toxicity (nephrotoxicity) is the primary concern — the proximal renal tubule is particularly vulnerable to uranium-induced oxidative damage [1]. Chronic low-level uranium exposure causes increased urinary protein and amino acids, markers of tubular dysfunction, before overt kidney failure [2]. The radiological carcinogenic risk at typical drinking water concentrations contributes additional long-term bone and lymphatic cancer risk, as uranium's daughter products (radium, radon) accumulate in the decay chain [1]. Elevated uranium has been documented in drinking water affecting tribal communities in the Navajo Nation, where uranium mining legacies have contaminated both wells and surface water [2].

Private well users in uranium-mining regions (Colorado Plateau, Wyoming, South Dakota) and uranium-rich geology face the highest drinking water exposures [1]. Navajo and other Indigenous communities near uranium mining legacy sites have documented elevated exposures and kidney disease rates [2]. Uranium miners and mill workers historically had extremely high inhalation exposures [1]. Gulf War veterans exposed to depleted uranium from armor-piercing rounds or destroyed vehicles have ongoing monitoring programs [2].

1. Test your private well for uranium if you live in a uranium-bearing region — test kits and certified labs are available through your state drinking water program [1]. 2. Reverse osmosis is the most effective water treatment for uranium removal; ion exchange and activated alumina are also effective [2]. 3. EPA's MCL of 30 µg/L is the legal standard for public water systems; many health advocates recommend a target below 20 µg/L given kidney effects at lower concentrations [1]. 4. If you are a uranium mining veteran or worker, engage the VA or NIOSH worker health programs for monitoring [2].