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Depleted uranium storage yard

Depleted Uranium (DU) is uranium remaining after removal of the isotope uranium-235. It is primarily composed of the isotope uranium-238. In the past it was called by the names Q-metal, depletalloy, and D-38, but these have fallen into disuse. Since depleted uranium contains at least three times less uranium-235 than natural uranium, it is weakly radioactive and an external radiation dose from depleted uranium is about 60% of that from the same mass of uranium with a natural isotopic ratio. Depleted uranium behaves in the body as does natural uranium.

At standard temperature and pressure (STP) it is a very dense metal solid. Due to its high density the main uses of depleted uranium include counterweights in aircraft, radiation shields in medical radiation therapy machines and containers for the transport of radioactive materials. The military uses depleted uranium for defensive armor plate and its pyrophoricity has made it a valued component in other military applications, particularly in the form of armor-piercing projectiles.

Its use in ammunition is controversial because of its release into the environment. Besides its residual radioactivity, U-238 is a heavy metal whose compounds are known from laboratory studies to be toxic to mammals, especially to the reproductive system and fetus development, causing reduced fertility, miscarriages and fetus malformations.

It remains debatable whether depleted uranium is dangerous to human beings at the low quantities in which it could possibly be ingested from environmental contamination.



Sources

Depleted uranium is produced as a byproduct during the process of forming enriched uranium from natural uranium. Enriched uranium is used in nuclear reactors. When the majority of fissile radioactive isotopes of uranium are removed from natural uranium, what remains is called depleted uranium. Another, less common, source of Depleted Uranium is reprocessed spent reactor fuel.

DU created by enrichment can be distinguished from DU created in a reactor by the percentage of uranium-236,[6] produced by neutron capture from uranium-235 in nuclear reactors, present in the material.

DU is considered both a toxic and radioactive hazard that requires long term storage as low level nuclear waste. DU is relatively expensive to store but relatively inexpensive to produce or obtain. Generally the only real costs are those associated with conversion of uranium hexafluoride (UF6) to metal. DU is extremely dense, 67% denser than lead, only slightly less than tungsten and gold, and just 16% less dense than osmium or iridium, the densest naturally occurring substances known. Its low cost makes it attractive for a variety of industrial and military uses.

However, the material is prone to corrosion and small particles are pyrophoric. [7]

 

History

Depleted uranium was first stored in stockpiles in the 1940s when the U.S. and USSR began their nuclear weapons and nuclear power programs. While it is possible to design civilian power reactors with un-enriched fuel, only about 10% of reactors ever built utilize that technology, and both nuclear weapons production and naval reactors require the concentrated isotope. Originally, DU was conserved in the hope that more efficient enrichment techniques would allow further extraction of the fissile isotope; however, those hopes have not materialized.

In the 1970s, The Pentagon reported that the Soviet military had developed armor plating for Warsaw Pact tanks that NATO ammunition couldn't penetrate. The Pentagon began searching for material to make denser bullets. After testing various metals, ordnance researchers settled on depleted uranium. DU was useful in ammunition not only because of its unique physical properties and effectiveness, but also because it was cheap and readily available. Tungsten, the only other candidate, had to be sourced from China. With DU stockpiles estimated to be more than 500,000 tons, the financial burden of housing this amount of low-level radioactive waste was very apparent. It was therefore more economical to use depleted uranium rather than storing it. Thus, from the late 1970s, the U.S., the Soviet Union, Britain and France, began converting their stockpiles of depleted uranium into kinetic energy penetrators.

Photographic evidence of destroyed equipment suggests that DU was first used during the 1973 Arab-Israeli war. Various written reports cite information that was obtained as a consequence of that use.^[1] However, while clearing the decades-old Hawaii Stryker firing range, workers have found depleted uranium ammunition from the 1960s.[citation needed]

The U.S. military used DU shells in the 1991 Gulf War, Bosnia war[8], Serbia bombing, and the 2003 Iraq War.^[2]

Production and availability

Natural uranium metal contains about 0.71% U-235, 99.28% U-238, and about 0.0054% U-234. In order to produce enriched uranium, the process of isotope separation removes a substantial portion of the U-235 for use in nuclear power, weapons, or other uses. The remainder, depleted uranium, contains only 0.2% to 0.4% U-235. Because natural uranium begins with such a low percentage of U-235, the enrichment process produces large quantities of depleted uranium.

For example, producing 1 kg of 5% enriched uranium requires 11.8 kg of natural uranium, and leaves about 10.8 kg of depleted uranium with only 0.3% U-235 remaining. (Depleted Uranium Fraction Calculator designed by The WISE Uranium Project)

The Nuclear Regulatory Commission (NRC) defines depleted uranium as uranium with a percentage of the ²³⁵U isotope that is less than 0.711% by weight (See 10 CFR 40.4.) The military specifications designate that the DU used by DoD contain less than 0.3% ²³⁵U (AEPI, 1995). In actuality, DoD uses only DU that contains approximately 0.2% ²³⁵U (AEPI, 1995).

Military applications

Approximate area and major clashes in which DU bullets and rounds were used in the Gulf War

Depleted uranium is very dense; at 19,050 kg/m³, it is almost 70% denser than lead. Thus a given weight of it has a smaller diameter than an equivalent lead projectile, with less aerodynamic drag and deeper penetration due to a higher pressure at point of impact. DU projectile ordnance is often incendiary because of its pyrophoric property.


Armor plate
Because of its high density, depleted uranium can also be used in tank armor, sandwiched between sheets of steel armor plate. For instance, some late-production M1A1HA and M1A2 Abrams tanks built after 1998 have DU reinforcement as part of its armor plating in the front of the hull and the front of the turret and there is a program to upgrade the rest, for example Chobham armor.


Nuclear weapons
Depleted uranium is used as a tamper in fission bombs and as a nuclear fuel in hydrogen bombs.


Ammunition
Most military use of depleted uranium has been as 30 mm and smaller ordnance, primarily the 30 mm PGU-14/B armor-piercing incendiary round from the GAU-8 Avenger cannon of the A-10 Thunderbolt II [9] used by the U.S. Air Force. 25 mm DU rounds have been used in the M242 gun mounted on the U.S. Army's Bradley Fighting Vehicle and LAV-AT.

The U.S. Marine Corps uses DU in the 25 mm PGU-20 round fired by the GAU-12 Equalizer cannon of the AV-8B Harrier, and also in the 20 mm M197 gun mounted on AH-1 helicopter gun-ships. The US Navy's Phalanx CIWS's M61 Vulcan gatling gun used 20 mm armor-piercing penetrator rounds with discarding plastic sabots which were made using depleted uranium, later changed to tungsten.

DU penetrator from the PGU-14/B incendiary 30mm round.

Another use of depleted uranium is in kinetic energy penetrators anti-armor role. Kinetic energy penetrator rounds consist of a long, relatively thin penetrator surrounded by discarding sabot. Two materials lend themselves to penetrator construction: tungsten and depleted uranium, the latter in designated alloys known as staballoys.

Staballoys are metal alloys of depleted uranium with a very small proportion of other metals, usually titanium or molybdenum.

One formulation has a composition of 99.25% by weight of depleted uranium and 0.75% by weight of titanium. Another variant can have 3.5% by weight of titanium. Staballoys are about twice as dense as lead and are designed for use in kinetic energy penetrator armor-piercing ammunition. The US Army uses DU in an alloy with around 3.5% titanium.

1987 photo of Mark 149 Mod 2 20mm depleted uranium ammunition

for the Phalanx CIWS aboard USS Missouri (BB-63).

Staballoys, along with lower raw material costs, have the advantage of being easy to melt and cast into shape; a difficult and expensive process for tungsten. Note also that according to recent research,[10] at least some of the most promising tungsten alloys which have been considered as replacement for depleted uranium in penetrator ammunitions, such as tungsten-cobalt or tungsten-nickel-cobalt alloys, possess extreme carcinogenic properties, which by far exceed those (confirmed or suspected) of depleted uranium itself: 100% of rats implanted with a pellet of such alloys developed lethal rhabdomyosarcoma within a few weeks.

On more properly military grounds, depleted uranium is favored for the penetrator because it is self-sharpening and pyrophoric. On impact with a hard target, such as an armored vehicle, the nose of the rod fractures in such a way that it remains sharp. The impact and subsequent release of heat energy causes it to disintegrate to dust and burn when it reaches air because of its pyrophoric properties (compare to ferrocerium).

When a DU penetrator reaches the interior of an armored vehicle, it catches fire, often igniting ammunition and fuel, killing the crew, and possibly causing the vehicle to explode. DU is used by the U.S. Army in 120 mm or 105 mm cannons employed on the M1 Abrams and M60A3 tanks. The Russian military has used DU ammunition in tank main gun ammunition since the late 1970s, mostly for the 115 mm guns in the T-62 tank and the 125 mm guns in the T-64, T-72, T-80, and T-90 tanks.

The DU content in various ammunition is 180 g in 20 mm projectiles, 200 g in 25 mm ones, 280g in 30 mm, 3.5 kg in 105 mm, and 4.5 kg in 120 mm penetrators. It is used in the form of Staballoy. The US Navy used DU in its 20 mm Phalanx CIWS guns, but switched in the late 1990s to armor-piercing tungsten for this application, because of the fire risk associated with stray pyrophoric rounds. DU was used during the mid-1990s in the U.S. to make 9 mm and similar caliber armor piercing bullets, grenades, cluster bombs, and mines, but those applications have been discontinued, according to Alliant Techsystems. Whether or not other nations still make such use of DU is difficult to determine.

It is thought that between 17 and 20 states have weapons incorporating depleted uranium in their arsenals. They include the USA, the UK, France, Russia, Greece, Turkey, Israel, Saudi Arabia, Bahrain, Egypt, Kuwait, Pakistan, Thailand, Iraq and Taiwan. DU ammunition is manufactured in 18 countries. Only the US and the UK have acknowledged using DU weapons.^[3]

 

Legal status in weapons

In 1996 the International Court of Justice (ICJ) gave an advisory opinion on the "legality of the threat or use of nuclear weapons".^[4] This made it clear, in paragraphs 54, 55 and 56, that international law on poisonous weapons, – the Second Hague Declaration of 29 July 1899, Hague Convention IV of 18 October 1907 and the Geneva Protocol of 17 June 1925 – did not cover nuclear weapons, because their prime or exclusive use was not to poison or asphyxiate.

This ICJ opinion was about nuclear weapons, but the sentence,

"The terms have been understood, in the practice of States, in their ordinary sense as covering weapons whose prime, or even exclusive, effect is to poison or asphyxiate."

Also removes depleted uranium weaponry from coverage by the same treaties as their primary use is not to poison or asphyxiate, but to destroy materiel and kill soldiers through kinetic energy.

The Sub-Commission on Prevention of Discrimination and Protection of Minorities of the United Nations Human Rights Commission,^[5] passed two motions^[6] the first in 1996^[7] and the second in 1997.^[8] They listed weapons of mass destruction, or weapons with indiscriminate effect, or of a nature to cause superfluous injury or unnecessary suffering and urged all states to curb the production and the spread of such weapons. Included in the list was weaponry containing depleted uranium.

The committee authorized a working paper, in the context of human rights and humanitarian norms, of the weapons. The requested UN working paper was delivered in 2002^[9] by Y.K.J. Yeung Sik Yuen in accordance with Sub-Commission on Promotion and Protection of Human Rights resolution 2001/36. He argues that the use of DU in weapons, along with the other weapons listed by the Sub‑Commission, may breach one or more of the following treaties:

1. the Universal Declaration of Human Rights

2. the Charter of the United Nations

3. the Genocide Convention

4. the United Nations Convention Against Torture

5. the Geneva Conventions including Protocol I

6. the Convention on Conventional Weapons of 1980

7. the Chemical Weapons Convention

Yeung Sik Yuen writes in Paragraph 133 under the title "Legal compliance of weapons containing DU as a new weapon":

“ Annex II to the Convention on the Physical Protection of Nuclear Material 1980 (which became operative on 8 February 1997) classifies DU as a category II nuclear material. Storage and transport rules are set down for that category which indicates that DU is considered sufficiently “hot” and dangerous to warrant these protections. But since weapons containing DU are relatively new weapons no treaty exists yet to regulate, limit or prohibit its use.

 

The legality or illegality of DU weapons must therefore be tested by recourse to the general rules governing the use of weapons under humanitarian and human rights law which have already been analyzed in Part I of this paper, and more particularly at paragraph 35 which states that parties to Protocol I to the Geneva Conventions of 1949 have an obligation to ascertain that new weapons do not violate the laws and customs of war or any other international law. As mentioned, the International Court of Justice considers this rule binding customary humanitarian law. ”

In 2001, Carla del Ponte, the chief prosecutor for the International Criminal Tribunal for the Former Yugoslavia, said that NATO's use of depleted uranium in former Yugoslavia could be investigated as a possible war crime.^[10] Louise Arbour, del Ponte's predecessor as chief prosecutor, had created a small, internal committee, made up of staff lawyers, to assess the allegation.

Their findings, that were accepted and endorsed by del Ponte,^[11] concluded that:

“ There is no specific treaty ban on the use of DU projectiles. There is a developing scientific debate and concern expressed regarding the impact of the use of such projectiles and it is possible that, in future, there will be a consensus view in international legal circles that use of such projectiles violate general principles of the law applicable to use of weapons in armed conflict. No such consensus exists at present. ^[12] ”

Requests for a general moratorium of military use

Some states and a coalition of over 80 non-governmental organizations have asked for a ban on the production and military use of depleted uranium weapons,^[13] The European Parliament has repeatedly passed resolutions requesting an immediate moratorium on the further use of depleted uranium ammunition.^[14][15]

Regarding this debate, the above mentioned working paper published in 2002 by the United Nations Sub-Commission on Promotion and Protection of Human Rights, at paragraph 171 under the title "Moratorium" reads:

“Considering the disturbing reports on the ill effects of DU weapons in the Gulf and the Balkans, it is saddening to note that so far appeals for a moratorium coming from different quarters have not yet prevailed. Killing first and asking questions later has, however, never been a sensible solution. ”

The NATO nations and permanent members of the United Nations Security Council, of France, the United Kingdom and the United States have consistently rejected calls for a ban,^[16] maintaining that its use continues to be legal, and that the health risks are entirely unsubstantiated.^[17] The UK government further alleges that cancers and birth defects in Iraq could be blamed on the Iraqi Government's use of chemical weapons on its own citizens.^[17]

 

Civilian applications

Civilian applications for depleted uranium are fairly limited and are typically unrelated to its radioactive properties. It primarily finds application as ballast because of its high density. Such applications include sailboat keels, as counterweights and sinker bars in oil drills, gyroscope rotors, and in other places where there is a need to place a weight that occupies as little space as possible. However other high density materials are sometimes preferred because uranium is prone to corrosion.

Other relatively minor consumer product uses have included: incorporation into dental porcelain used for false teeth to simulate the fluorescence of natural teeth; and in uranium-bearing reagents used in chemistry laboratories (eg. uranyl acetate, used in analytical chemistry and as a stain in electron microscopy).

Uranium was widely used as a coloring matter for porcelain and glass in the 19th century. The practice was believed to be a matter of history, however in 1999 concentrations of 10% depleted uranium were found in "jaune no.17" a yellow enamel powder that was being produced in France by Cristallerie de Saint-Paul, a manufacturer of enamel pigments. The depleted uranium used in the powder was sold by Cogéma's Pierrelatte facility. Cogema has since confirmed that it has made a decision to stop the sale of depleted uranium to producers of enamel and glass. [11]

DU is also used for shielding for radiation sources used in medical and industrial radiography.

U.S. Nuclear Regulatory Commission regulations at 10 CFR 40.25 establish a general license for the use of depleted uranium contained in industrial products or devices for mass-volume applications. This general license allows anyone to possess or use Depleted Uranium for authorized purposes. Generally, a registration form is required, along with a commitment to not abandon the material. Agreement States may have similar, or more stringent, regulations.
 

Trim weights in aircraft

Aircraft may also contain depleted uranium trim weights (a Boeing 747-100 may contain 400 to 1,500 kg). This application of DU is controversial. If an aircraft crashes there is concern that the uranium would enter the environment: the metal can oxidize to a fine powder in a fire. Its use has been phased out in many newer aircraft; Boeing and McDonnell-Douglas discontinued using DU counterweights in the 1980s.

Some amount of depleted uranium was released e.g. during the Bijlmer disaster, when 152 kg was 'lost'. Counterweights are manufactured with cadmium plating and are considered non-hazardous while the plating is intact.[12]


Uranium hexafluoride

About 95% of the depleted uranium produced is stored as uranium hexafluoride, (D)UF⁶, in steel cylinders in open air yards close to enrichment plants. Each cylinder contains up to 12.7 tonnes (or 14 US tons) of UF6. In the U.S. alone, 560,000 tonnes of depleted UF6 had accumulated by 1993. In 2005, 686,500 tonnes in 57,122 storage cylinders were located near Portsmouth, Ohio, Oak Ridge, Tennessee, and Paducah, Kentucky. [13], [14]

The long-term storage of DUF⁶ presents environmental, health, and safety risks because of its chemical instability. When UF6 is exposed to moist air, it reacts with the water in the air to produce UO²F² (uranyl fluoride) and HF (hydrogen fluoride) both of which are highly soluble and toxic. Storage cylinders must be regularly inspected for signs of corrosion and leaks. The estimated life time of the steel cylinders is measured in decades. [15]

Hexafluoride tank leaking

There have been several accidents involving uranium hexafluoride in the United States. [16] The U.S. government has been converting DUF⁶ to solid uranium oxides for disposal. [17] Such disposal of the entire DUF⁶ inventory could cost anywhere from 15 to 450 million dollars. [18]
 

Health considerations
 

Radiological hazards
Depleted uranium is not a significant health hazard unless it is taken into the body. External exposure to radiation from depleted uranium is generally not a major concern because the alpha particle emitted by its isotopes travel only a few centimeters in air or can be stopped by a sheet of paper. Also, the uranium-235 that remains in depleted uranium emits only a small amount of low-energy gamma radiation.

According to the World Health Organization, a radiation dose from it would be about 60% of that from purified natural uranium with the same mass. Approximately 90 µg (micrograms) of natural uranium, on average, exist in the human body as a result of normal intakes of water, food and air. The majority of this is found in the skeleton, with the rest in various organs and tissues.

The radiological dangers of pure depleted uranium are relatively low, lower (60%) than those of naturally-occurring uranium due to the removal of the more radioactive isotopes, as well as due to its long half-life (4.46 billion years). Depleted uranium differs from natural uranium in its isotopic composition, but its biochemistry is for the most part the same. For further details see Actinides in the environment.


Chemical hazards
Health effects of DU are determined by factors such as the extent of exposure and whether it was internal or external. Three main pathways exist by which internalization of uranium may occur: inhalation, ingestion, and embedded fragments or shrapnel contamination. Properties such as phase (e.g. particulate or gaseous), oxidation state (e.g. metallic or ceramic), and the solubility of uranium and its compounds influence their absorption, distribution, translocation, elimination and the resulting toxicity. For example, metallic uranium is relatively non-toxic compared to hexavalent uranium(VI) compounds such as uranyl nitrate. ^[18]

Uranium is pyrophoric when finely divided. It will corrode under the influence of air and water producing insoluble uranium(IV) and soluble uranium(VI) salts. Soluble uranium salts are toxic. Uranium accumulates in several organs, such as the liver, spleen, and kidneys. The World Health Organization has established a daily "tolerated intake" of soluble uranium salts for the general public of 0.5 µg/kg body weight, or 35 µg for a 70 kg adult.

The chemical toxicity of uranium salts is greater than their radiological toxicity. Its radiological hazards are dependent on the purity of the uranium, and there has been some concern that depleted uranium produced as a by-product of nuclear reprocessing may be contaminated with more dangerous isotopes: this should not be a concern for depleted uranium produced as tailings from initial uranium enrichment.

Early scientific studies usually found no link between depleted uranium and cancer, and sometimes found no link with increases in the rate of birth defects [citation needed], but today the damaging effects of uranium assumption on the reproductive cycle (reduced fertility, miscarriages, abortions, congenital defects at birth) of small laboratory mammals (mice, hamsters) are well studied.

There is no direct and definitive proof that uranium causes birth defects in humans (uranium poisoning of humans is fortunately a rare occurrence) but it may, at least at very high doses, given the extreme similarity of mammalian reproductive cycles at the physical and biochemical levels. Environmentalist, pacifist and humanitarian organizations, as well as several left and center-left politicians, especially in Europe, have expressed concern about the health effects of depleted uranium [19], and there is significant scientific and political debate over the matter.

Concerns about the use of this material, particularly in ammunitions, refer to its proven mutagenicity ^[19], the already mentioned teratogenicity ^[20],^[21]neurotoxicity ^[22], and probable carcinogenic and leukemogenic potential ^[23] believed to be due both to its slow radioactivity and to its toxicity, which regarding carginogenity may act similarly to other heavy metals such as lead.

Early studies of depleted uranium aerosol exposure assumed that uranium combustion product particles would quickly settle out of the air[20] and thus could not affect populations more than a few kilometers from target areas[21], and that such particles, if inhaled, would remain un-dissolved in the lung for a great length of time and thus could be detected in urine[22].

On the other hand, it has been suggested that the known critical doses for acute (short term) uranium intoxication could be exceeded in the scenario of farmers living in a polluted area, and accidentally ingesting contaminated soil, for example by children while playing, while doses sufficient for a chronic (long term) intoxication could be reached simply through daily consumption of contaminated water and food.[23] In practice, however, measurements made in those areas where depleted uranium ammunitions were used extensively did not find significantly higher than average uranium concentrations in the soil, just a few months after contamination. [24]

Other studies have shown that DU ammunition has no measurable detrimental health effects, either in the short or long term. The International Atomic Energy Agency reported in 2003 that,

"based on credible scientific evidence, there is no proven link between DU exposure and increases in human cancers or other significant health or environmental impacts," although "Like other heavy metals, DU is potentially poisonous. In sufficient amounts, if DU is ingested or inhaled it can be harmful because of its chemical toxicity. High concentration could cause kidney damage"[25].

The Basra hospital data
 

Graph showing the rate per 1,000 births of congenital malformations observed at Basra University Hospital, Iraq,

as reported by I. Al-Sadoon, et al., writing in the Medical Journal of Basrah University.

Uranium_bestanden/DEPLETED URANIUM-2- INCIDENCE.htm

Following the first gulf war, scientists at the Basra hospital and university have monitored the incidence of leukemia and other malignancies among children in the Basra area, and of congenital malformations in newborn children. The data for the period 1990–2001 show an incidence increase of 426% for general malignancies, 366% for leukemia and of over 600% for birth defects, with all series showing a roughly increasing pattern with time.

These data, being the largest set of epidemiological data available for the Iraqi population, have received considerable attention; and since it reported a very large increase in those pathologies which are known or strongly suspected to be related to uranium poisoning, it has been natural to consider the possibility that such increase had indeed been caused by depleted uranium contamination.

The connection, however, is far from being obvious or proven:

1. first of all, there is a considerable delay (at least ten years) between the occurrence of contaminations and the peak of incidence of malformations and malignancies, which leads to speculative hypotheses about the process of accumulation of uranium in the human body

2. secondarily, there could be other causes or concurrent causes, for example different kinds of pollution related or unrelated to the war (e.g. burning oil wells), or the 1990–2003 Iraq sanctions which led to a collapse of the Iraqi economy and in general to a dramatic impoverishment of the population with a sharp decrease of nutritional and hygienic conditions (which alone, however, cannot explain why the increase in congenital defects is the highest observed)

In general, the prevailing scientific view on the matter [26],[27],[28] is that such data, and other scarce data available, do not conclusively prove a poisoning effect of depleted uranium; but that the possibility exists and cannot be ruled out either, and so a precautionary principle would suggest to suspend the use of such weapons.

 

Other relevant contamination cases

On October 4, 1992, an El Al Boeing 747-F cargo aircraft Flight 1862, crashed into an apartment building in Amsterdam. After reports of local residents and rescue workers complaining of health issues related to the release of depleted uranium used as counterbalance in the plane, authorities began an epidemiological study in 2000 of those believed to be affected by the accident.

The study concluded that because exposure levels were so low, it was improbable that exposure to depleted uranium was the cause of the reported health complaints.^[24]


Gulf War syndrome and soldier complaints
Increased rates of immune system disorders and other wide-ranging symptoms, including chronic pain, fatigue and memory loss, have been reported in over one quarter of combat veterans of the 1991 Gulf War [29]. It has not always been clear whether these were related to Gulf War service, but combustion products from depleted uranium munitions are still being considered as one of the potential causes by the Research Advisory Committee on Gulf War Veterans' Illnesses, as DU was used in tank kinetic energy penetrator and machine-gun bullets on a large scale for the first time in the Gulf War.

A two year study headed by Sandia National Laboratories’ Al Marshall analyzed potential health effects associated with accidental exposure to depleted uranium during the 1991 Gulf War. Marshall’s study concluded that the reports of serious health risks from DU exposure are not supported by veteran medical statistics and were consistent with earlier studies from Los Alamos and the New England Journal of Medicine.^[25]

One particular subgroup of veterans which may be at higher risk comprises those who have retained internally fragments of DU from shrapnel wounds. A laboratory study on rats produced by the Armed Forces Radiobiology Research Institute [30] showed that, after a study period of 6 months, rats treated with chronical doses of depleted uranium coming from implanted pellets comparable to the levels (in μg/kg) found on average in the urines of Desert Storm veterans with retained DU fragments, had developed a slight (not statistically significant) tendency to lose weight with respect to the control group, as well as two isolated cases of total inability to eat, one of which caused by abnormal tooth growth.

More importantly, the high dose group, which was maintained at a chronical level of DU roughly 5 times greater than found in veterans, had developed a significant tendency to lose weight with respect to the control group; substantial amounts of uranium were accumulating in their brains and central nervous systems, and showed a significant reduction of neuronal activity in the hippocampus in response to external stimuli. The conclusions of the study show that brain damage from chronic uranium intoxication is possible at lower doses than previously thought, though possibly not as low as those generally measured in veterans with internally retained DU fragments.

However, results from computer based neurocognitive tests on veterans have indeed showed a correlation between the levels of urinary uranium and "problematic performance" on tests assessing performance accuracy and efficiency. [31]. Also, veterans with internally retained DU fragments might be more exposed to cancer and leukemia risks [32],[33], although scarcity of statistical data makes a precise assessment of such risk difficult.

Some American soldiers more recently employed are also complaining of symptoms or illnesses which they attribute to exposure to depleted uranium. The correlation has not been confirmed and the hypothesis ignores the multitude of other exposures that soldiers in a war situation are likely to receive.^[26]

The U.S. Army has commissioned some research into risks and harms of depleted uranium. Scientific documents produced by the Armed Forces Radiobiology Research Institute write of the "numerous unanswered questions about its [of DU] long term health effects", state that "moderate exposure to either DU or uranium presents a significant toxicological threat" [34] and strongly suggest "low dose DU induced carcinogenesis" which might affect military personnel following shrapnel wounds or inhalation [35].

The above mentioned research projects, in particular, focus on finding in advance complete toxicological information for possible replacement materials for depleted uranium in projectiles, such as tungsten alloys, and on developing drugs capable of suppressing the biochemical process by which DU supposedly generates tumoral forms in the human body.

The same institution is also working on methods allowing a more rapid and efficient detection of uranium contamination in human beings [36] and has developed a standardized procedure for medical assistance to military personnel exposed to depleted uranium contamination. [37]

 

Footnotes