Depleted uranium (DU) is a dense metal that is a byproduct of the uranium enrichment process, where the more radioactive isotopes of natural uranium are removed for use in nuclear fuel. This material retains some radioactivity, though it is about 40% less radioactive than natural uranium. Due to its high density, approximately 1.7 times denser than lead, DU is utilized in various applications such as armor-piercing munitions and as counterweights in aircraft.
Pathways of Depleted Uranium Exposure
Individuals can be exposed to depleted uranium through several pathways, with the form of DU significantly influencing exposure risk. One primary pathway is inhalation, especially when fine dust or aerosols containing DU are created, such as during the impact of armor-piercing munitions in combat zones or in industrial settings where DU is processed. These fine particles can remain in the lungs for extended periods, potentially years, if they are insoluble.
Another route of exposure is ingestion, which can occur by swallowing contaminated soil, water, or food particles. While less significant for systemic effects than inhalation, it is still a consideration.
Wound contamination is also a direct pathway, where DU fragments or shrapnel become embedded in the body, releasing uranium into the bloodstream over time. Lastly, dermal contact, or direct skin exposure, is less significant for systemic health effects because alpha particles emitted by DU do not readily penetrate the skin.
Immediate Health Effects
Acute exposure to significant levels of depleted uranium primarily results in health effects due to its chemical toxicity as a heavy metal, rather than its radioactivity. The kidneys are particularly susceptible to damage from uranium, which can impair their function. Symptoms of kidney impairment may include changes in urine output, swelling, and imbalances in electrolytes.
Gastrointestinal distress, such as nausea, vomiting, diarrhea, or abdominal pain, can also occur shortly after exposure. If DU dust is inhaled, respiratory irritation may develop, leading to symptoms like coughing or shortness of breath. Acute neurological symptoms such as headaches, dizziness, or fatigue are also potential outcomes.
Long-Term Health Considerations
Long-term or significant depleted uranium exposure raises concerns about chronic and delayed health effects. The potential for DU exposure to increase cancer risk is a subject of ongoing scientific research. While uranium is radioactive, its chemical toxicity is generally considered the primary health concern, with some studies suggesting that internal irradiation from insoluble uranium particles retained in the lung could lead to lung cancer over prolonged periods.
However, some studies have found no evidence of cancer in individuals with elevated uranium levels from embedded fragments. Concerns also exist regarding reproductive and developmental effects, including potential links to birth defects or fertility problems.
Chronic neurological symptoms, such as cognitive impairment, memory issues, or mood disturbances, have been observed in animal studies but are not consistently reported in human cohorts. Additionally, DU can accumulate in bone tissue, with a half-life in bone ranging from 70 to 200 days, raising questions about potential long-term effects on bone health.