The Hazards of Depleted Uranium
Is there a way to clean up battlefields?
The US has announced that it is sending depleted uranium (DU) anti-tank rounds to the Ukrainians. This follows Britain’s announcement that they are sending DU ammunition to Ukraine too.
The DU rounds were developed by NATO countries during the Cold War in order to neutralize the advantage of Soviet tanks in a possible tank war in Europe.
Using DU to defeat tank armor isn’t a new idea. Interest in it began over 50 years ago as engineers tried to find a new way to tank armor. One advantage of DU is that it is twice as heavy as lead (the heavier the metal, the higher the kinetic energy and the better it is to penetrate armor). And, instead of the point of the anti-tank round mushrooming out as it hits a hard armor, it retains its sharp point as it burrows its way into the tank armor. Although the data on DU munitions is classified, it appears to be 40% more powerful than tungsten penetrators.
There is also a large stockpile of DU since it is a byproduct of separating the uranium isotope U-235 from natural uranium, which is used in producing nuclear weapons and nuclear reactor rods. In fact, in 1998, the US Department of Energy had half a million tons of DU. Since only 10 tons of DU were used in Kosovo and 320 tons in the Gulf War, the military is hardly running out of material.
However, DU use isn’t limited to the UK and US. Russia has DU munitions stockpiles although there is no proof that it is being used in Ukraine. France, Greece, Turkey, Israel, Saudi Arabia, Bahrain, Oman, Egypt, Kuwait, Pakistan, Thailand, China, India, and Taiwan have DU munitions.
DU is also used as ballast in aircraft, helicopters, and ships. And, ironically, it is used as radiation shielding.
Is DU Toxic?
DU is radioactive. However, since DU has the more radioactive uranium isotope, U-235 removed, it is only 40% as radioactive as naturally occurring uranium.
The radioactivity of DU is deemed less hazardous than natural uranium. Most of the radioactivity is alpha and beta radiation. Alpha radiation is unable to penetrate clothing. Beta radiation can’t penetrate human skin. Unless the DU penetrates the bone marrow, it is relatively harmless. A 2016 UN Scientific Committee on the effects of atomic radiation found, “limited significant poisoning was caused by exposure to depleted uranium.”
Of course, the risk depends on the state of the DU. Unfired penetrator rods are covered with a shielding that stops alpha and beta radiation. It is more hazardous after it has hit the target.
Uranium burns in the presence of heat and oxygen, leaving uranium oxides. If they are inhaled, they end up in the lungs, where most of it is collected by mucus and is eventually expelled out of the body. They can also be ingested or enter the body through a cut. That’s why soldiers and civilians should avoid destroyed tanks until they are neutralized by decontamination.
Collecting souvenirs of destroyed tanks is dangerous as the expended munitions are unprotected and radioactive particles can remain on the skin.
Fortunately, uranium and uranium oxides are non-soluble, which means it will not contaminate the ground water. Since the range of the radioactivity is limited, the threat to growing food at the site is also limited.
Although many analysts are concerned about DU’s threat, it is less than many of the explosives used on the battlefield.
The Environmental Protection Agency (EPA) has declared TNT – a frequent military explosive – a pollutant whose removal is priority. The EPA maintains that TNT levels in soil should not exceed 17.2 gram per kilogram of soil and 0.01 milligrams per liter of water.
Areas where there have been major artillery battles exceed these levels.
Most explosives are persistent and can remain for years in soil and groundwater. And, while TNT tends to remain in the soil at the blast site, RDX and HMX tend to migrate into the groundwater. Another problem with TNT and RDX is that bacteria in the soil can’t easily break them down into safer byproducts.
Detonators for high explosives pose additional problems because they contain heavy metals. A frequent detonator ingredient is lead azide. The delay elements consist of various chemicals, mainly lead oxide, silicon, antimony, and potassium permanganate.
DU has contaminated many battlefields in Iraq and Syria, to mention two.
Is there any way to clean up the contaminants?
The conventional way is to dig up the contaminated dirt and isolate it. However, there are new possibilities like phytoremediation.
Phytoremediation uses a type of plant called hyperaccumulators. These plants naturally accumulate high levels of toxic materials found in the soil as they grow. In nature, this process protects the plant by killing insects, fungi, and molds that threaten them. It also discourages larger, plant eating animals by making them sick. As a result, the animalsgive them a wide berth.
Today environmental experts use this natural mechanism to treat explosives contaminated sites. Tobacco plants are being used to degrade organic explosives like TNT and yellow poplar saplings can collect mercury compounds at sites that used mercury for detonators.
One successful example was the use of sunflowers to remove radioactive contaminants from pond water at Chernobyl.
Other plants that can accumulate compounds used in explosives are geraniums (Benzene and other hydrocarbons), Bermuda Grass (hydrocarbons), and pine trees (organicsolvents). White Rot Fungus, although not as attractive, is effective against compounds used in explosives like toluene and benzene.
Despite the attractiveness of phytoremediation, it does have its limitations. It is not a fast process and takes a commitment of many seasons before contamination levels are reduced to a safe level. The process is also limited to the ability of the roots to reach the contamination. However, for those places where it works, it is a more attractive alternative to traditional striping and storing of contaminated soil.
The environmental threat isn’t limited to DU. When the Ukraine War ends, cleaning up the contamination of warfare will be a must, especially in and around the farming communities.