Depleted Uranium: Health & Environmental Impact

 Depleted uranium (DU), a byproduct of natural uranium processing, often sparks discussions due to its health and environmental ramifications. This naturally occurring chemical element is recognized largely for its role in nuclear reactors and weaponry. But what exactly is "depleted uranium," and how does it affect our health and the environment?

Understanding Depleted Uranium

Natural uranium must undergo an "enrichment" process to create the fuel for specific types of nuclear reactors or to manufacture nuclear weapons. This process increases the percentage of the U-235 isotope, which is essential for nuclear fission. Natural uranium contains a U-235 concentration of 0.72 percent by mass, which can be elevated to between 2 and 94 percent through enrichment.

What is left after extracting the enriched uranium is a uranium mixture with significantly lowered concentrations of U-235 and U-234. This leftover substance is what we refer to as "depleted uranium." Defined by the Nuclear Regulatory Commission (NRC), it is uranium where the weight percentage fraction of U-235 is below 0.711 percent. Commonly in military applications, the weight percentage concentration of uranium isotopes is 99.8% U-238; 0.2% U-235; 0.001% U-234.

Applications of Depleted Uranium

Depleted uranium finds widespread use, particularly in the military and aerospace industries. Its high density makes it perfect for creating projectiles and missiles capable of piercing thick armor, such as tanks. However, its use has caused concerns due to potential environmental and health implications of uranium exposure following the explosion of these munitions. Depleted uranium also serves as radiation shielding in some medical devices, including X-rays, safeguarding patients and medical personnel from ionizing radiation.

Radioactivity of Depleted Uranium

Compared to natural uranium, depleted uranium exhibits significantly lower radioactivity. This is attributed to fewer U-234 and U-235 isotopes per unit mass and the removal of most radioactive decay products beyond U-234 and Th-231 during uranium mining and chemical treatment, which happens before enrichment. 

To clarify, the specific activity of uranium in depleted uranium is only 14.8 becquerels per milligram, whereas natural uranium has 25.4 becquerels per milligram. This means depleted uranium releases less radiation per unit mass than natural uranium. However, it's important to acknowledge that uranium decay products can take a long time to reach radioactive equilibrium with uranium isotopes, contributing to lower radioactivity compared to natural uranium and making it a less radiologically hazardous option.

Health Implications

Depleted uranium exposure can pose several health risks. Microscopic particles of depleted uranium dust can be inhaled or ingested, potentially damaging the lungs and kidneys. High intake of uranium is primarily a chemical toxicity concern rather than a radiological one. Despite its radioactive nature, its main imp act on health once inside the body is related to its chemical effects on bodily functions.

In many countries, exposure limits for soluble uranium compounds are defined to maintain a maximum concentration of 3 micrograms of uranium per gram of kidney tissue. Any effects resulting from exposure at these levels are generally considered mild and temporary. Current regulatory practices, based on these limits, provide adequate protection for workers in the uranium industry. As with any radioactive material, there is a risk associated with the development of cancers caused by exposure to radiation emitted from uranium. This risk is directly proportional to the amount of radiation received.

Consequences for environmental contamination

When munitions containing depleted uranium are used, localized environmental impacts can occur. During the explosion, depleted uranium particles can be dispersed into the surrounding environment, contaminating soil and water. This contamination can have long-term consequences on the ecosystem and environmental health of the area. Organisms living in the contaminated environment may be exposed to the radioactivity, possibly adversely affecting their health and local populations.

Contamination can also reach the food chain. Plants and animals can absorb depleted uranium from soil or water, and this can be transmitted to animals that feed on them. Therefore, potential human exposure is determined if these species enter the human food chain. Therefore, the safe and long-term management of depleted 

uranium is critical. Radioactive material must be properly disposed of to avoid future severe environmental impacts.