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Health and environmental effects of depleted uranium

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Depleted uranium (DU) is uranium which contains a reduced proportion of the fissile isotope U-235. It is a waste product from the enrichment of natural uranium for use in nuclear reactors. It is about half as radioactive as natural uranium, largely because it is also depleted in U-234. Depleted uranium is what is left over when most of the more radioactive isotopes of uranium are removed.

As a radioactive byproduct otherwise requiring long term storage as low level nuclear waste, depleted uranium is an inexpensive but controlled material. It has some uses related to its extremely high density, which is only slightly less than that of tungsten. However, it has extremely poor corrosion properties, is pyrophoric (it will burn spontaneously when small particles are exposed to air), and since it is a teratogen and a neurotoxin as well as being radioactive, the facilities for processing it need to monitor and filter dust, airborne particles, combustion products, vapors, and fumes. Disadvantages also include the need for depleted uranium to be handled with care as a toxicant radioactive heavy metal, and the fact that it spalls easily during metalworking.

History

DU started to be stored in stockpiles in the 1940's when the U.S. and U.S.S.R. began their Nuclear Weapons and Nuclear power Programs. While it is quite possible to design civilian power reactors with unenriched fuel both nuclear weapons production and submarine reactors require the concentrated isotope. Originally it was conserved in hopes that more efficient enrichment techniques would allow further extraction of the fissile isotope; however those did not materise. The Pentagon reported in the 1970s that the Soviet military had developed armor plating for Warsaw Pact tanks that NATO ammunition couldn't penetrate, and began searching for material to make harder bullets after testing various metals, ordnance researchers settled on depleted uranium.

What caused this particular material to be utilized as a form of ammunition was not only its unique physical properties and effectiveness in that role, but the fact that it was readily available, whereas tungsten, the only other candidate had to be sourced from China. With DU stockpiles estimated to be in excess of 500,000 tons, the financial burdens associated with the housing of this kind of material quickly became apparent and that too made it more economical to use rather than store. Thus from the late 1970s onwards the US, the Soviet Union, Britain and France, began converting otherwise useless stockpiles of DU 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.

The US and NATO Armed Forces argue that there is negligible increases in radioactivity due to the use of DU and thus it poses little or no health risk, however this is not taking into account the toxic properties of DU which far outweighs it radiological hazard. Mounting concerns from concerned groups from within and other nations have prompted calls for a ban on the use of this material. However the cost/benefits of this effective munition will mean that it will continue to be used regardless of current criticism, which in turn, may exacerbate the long term impact of DU use on the environment and human health.

Dirty DU

There are two basic types of DU, called "clean" and "dirty". The "clean" variety is obtained as a by-product of the extraction of uranium-235 from ore in the production of nuclear fuel or nuclear weapons. "Dirty" DU is what is left over when spent reactor fuel has been reprocessed. This means it may be contaminated with far more dangerous radioactive isotopes such as plutonium.

It had been widely assumed until 2001 that the type used by the US in its weapons was the "clean" variety. But research by UN scientists found evidence of "dirty" DU in the field. The next day, the problem was admitted by the U.S. Army, and steps were begun to correct the issue.

Safety and environmental issues

About 95% of the depleted uranium produced to date is being stored as uranium hexafluoride, (D)UF6, within steel cylinders in open air yards adjacent to enrichment plants. Each cylinder contains up to 12.7 tonnes (or 14 tons) of UF6. In the U.S. alone, 560,000 metric tons of depleted UF6 had accumulated by 1993. As of 2005, 686,500 metric tons in 57,122 storage cylinders were located near Portsmouth, Ohio, Oak Ridge, Tennessee, and Paducah, Kentucky. , The long-term storage of DUF6 presents environmental, health, and safety hazards due to 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 evidence of corrosion and leakage. The estimated life time of the steel cylinders is measured in decades.

DUF6 cylinders: painted (left) and corroded (right)

There have been several accidents involving uranium hexafluoride in the United States. The vulnerability of DUF6 storage cylinders to terrorist attack is apparently not the subject of public reports. However, the U.S. government has been converting DUF6 to solid uranium oxides for disposal. Such disposal of the entire DUF6 inventory could cost anywhere from 15 to 450 million dollars.

World Depleted Uranium Inventory
Country Organization DU Stocks (000 Kg) Reported
United States USA DOE 480,000 2002
Russia Russia FAEA 460,000 1996
France France COGEMA 190,000 2001
United Kingdom UK BNFL 30,000 2001
Germany Germany URENCO 16,000 1999
Japan Japan JNFL 10,000 2001
China China CNNC 2,000 2000
South Korea South Korea KAERI 200 2002
South Africa South Africa NECSA 73 2001
TOTAL 1,188,273 2002
Source: WISE Uranium Project

Health concerns

It should be noted that while this section addresses the health concerns of depleted uranium all isotopes and compounds of uranium are toxic to various degrees and the information presented here may be generalised to apply to most of them.

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. (See «Gmelin Handbuch der anorganischen Chemiek» 8th edition, English translation, Gmelin Handbook of Inorganic Chemistry, vol. U-A7 (1982) pp. 300-322.)

Projectile DU munitions can cause substantial inhalation exposure risks. Those risks have been associated with a number of health concerns, some of which are controversial.

See also: Depleted uranium, incendiary projectile munitions

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, but newer studies have and offered explanation of birth defect links. There is no direct proof that uranium causes birth defects in humans, but it induces them in several other species of mammals, and human epidemiological evidence is consistent with increased risk of birth defects in the offspring of persons exposed to DU.. Environmental groups and others have expressed concern about the health effects of depleted uranium, and there is significant debate over the matter. Some people have raised concerns about the use of this material, particularly in munitions, because of its proven mutagenicity , teratogenicity , in mice, and neurotoxicity , and its suspected carcinogenic potential, because it remains radioactive for an exceedingly long time with a half-life of approximately 4.5 billion years; and because it is also toxic in a manner similar to lead and other heavy metals. The primary radiological hazards associated with this material are beta and alpha emissions, however the long half-life indicates that depleted uranium is only weakly radioactive. All isotopes and compounds of uranium are toxic. Such issues are of concern to civilians and troops operating in a theatre where DU is used, and to people who will live for several years afterward in such areas or breathing air or drinking water from these areas.

Studies showing detrimental health effects have shown the following:

  • Indications that DU passes into humans more easily than previously thought after battlefield use. (radioactive particles absorbed into the body are far more harmful than a similar background radiation level outside the body, due to their immediate proximity to delicate structures such as DNA, bone marrow and the like.) Pre-1993 military DU studies mainly evaluated external exposure only.
  • DU can disperse into the air and water, United Nations Environment Programme (UNEP) study says in part:
"The most important concern is the potential for future groundwater contamination by corroding penetrators (ammunition tips made out of DU). The munition tips recovered by the UNEP team had already decreased in mass by 10-15% in this way. This rapid corrosion speed underlines the importance of monitoring the water quality at the DU sites on an annual basis."

Because DU is a chemical toxicant heavy metal with nephrotoxic (kidney-damaging), teratogenic (birth defect-causing), and potentially carcinogenic properties, there is a connection between uranium exposure and a variety of illnesses. The chemical toxicological hazard posed by uranium dwarfs its radiological hazard because it is only weakly radioactive. In 2002, A.C. Miller, et al., of the U.S. Armed Forces Radiobiology Research Institute, found that the chemical generation of hydroxyl radicals by depleted uranium in vitro exceeds radiolytic generation by one million-fold. Hydroxyl radicals damage DNA and other cellular structures, leading to cancer, immune system damage in white blood cells, birth defects in gonocytes (testes), and other serious health problems. (See Halliwell and Gutteridge, eds. (1999) Free Radicals in Biology and Medicine, 3rd ed., Oxford University Press.) In 2005, uranium metalworkers at a Bethlehem plant near Buffalo, New York, exposed to frequent occupational uranium inhalation risks, were found to have the same patterns of symptoms and illness as Gulf War Syndrome victims,.

A report written by an Irish petro-chemical engineer stated that in Iraq, the death rate per 1000 Iraqi children under 5 years of age increased from 2.3 in 1989 to 16.6 in 1993, and cases of lymphoblastic leukaemia more than quadrupled. (K. Rirchard (1998) Does Iraq's depleted uranium pose a health risk? The Lancet, Volume 351, Number 9103). I. Al-Sadoon, et al., writing in the Medical Journal of Basrah University, report a similar increase (see Table 1 here). However, Dr. Richard Guthrie, an expert in chemical warfare at Sussex University, has argued that a more likely cause for the increase in birth defects was the Iraqi Army’s use of teratogenic mustard agents. Since more recent epidemiological findings have come to light, only the plaintifs in a long-running class action lawsuit continue to assert that sulphur mustards might be responsible. According to their CDC toxicological profile, for sulphur mustards to have produced as many birth defects as have been observed, they would have had to have also produced several dozen times as many cancers as observed. (See Gulf War syndrome for more details specifically on the controversy over the use of depleted uranium in the Persian Gulf War.)

File:Basrah birth defects.gif
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, (see Table 1 here).

Several sources have attributed the increase in the rate of birth defects in the children of Gulf War veterans and in Iraqis to depleted uranium inhalation exposure,. A 2001 study of 15,000 February 1991 U.S. Gulf War combat veterans and 15,000 control veterans found that the Gulf War veterans were 1.8 (fathers) to 2.8 (mothers) times more likely to have children with birth defects. In a study of U.K. troops, "Overall, the risk of any malformation among pregnancies reported by men was 50% higher in Gulf War Veterans (GWV) compared with Non-GWVs". After repeated requests, the Naval Health Research Center has refused to release the trend information from the Birth and Infant Health Registry concerning these elevated levels of birth defects. Birth defects recorded among Iraqi civilians, and U.S. and U.K. troops show similar accelerating patterns.

Early studies of depleted uranium aerosol exposure assumed that uranium combustion product particles would quickly settle out of the air and thus could not affect populations more than a few kilometers from target areas, and that such particles, if inhaled, would remain undissolved in the lung for a great length of time and thus could be detected in urine. But those studies ignored uranium trioxide gas -- also known as uranyl oxide gas, or UO3(g) -- which is formed during uranium combustion (R.J. Ackermann, et al., "Free Energies of Formation of Gaseous Uranium, Molybdenum, and Tungsten Trioxides," Journal of Physical Chemistry, vol. 64 (1960) pp. 350-355, "gaseous monomeric uranium trioxide is the principal species produced by the reaction of U3O8 with oxygen." U3O8 being the dominant aerosol combustion product .) Uranyl ion contamination has been found on and around depleted uranium targets . UO3 gas remains dissolved in the atmosphere for weeks, but as a monomolecular gas is absorbed immediately upon inhalation, leading to accumulation in tissues including gonocytes (testes ) and white blood cells , but virtually no residual presence in urine other than what might be present from coincident particulate exposure.

By contrast, 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."

In October, 1992, an El Al Boeing 747-F cargo aircraft crashed in a suburb of Amsterdam. After reports of local residents and rescue workers complaining of heath 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 effected by the accident. The study concluded that because exposure levels were so low, it was highly improbable that exposure to depleted uranium was the cause of the reported health complaints.

The primary health impact of depleted uranium relates to its chemical toxicity as a heavy metal rather than to its radioactivity, which is relatively low. In fact, there is some evidence to suggest that low-level radiation, such as that from uranium, is beneficial to human beings. As with any heavy metal, the overall hazard depends on the amount of exposure.

The symptoms of Gulf War Syndrome can be explained by uranium combustion product inhalation exposure. Until the extent of uranyl oxide gas vapor production is known, the amount of uranium in exposure victims bodies will only be measurable through invasive techniques. Metallic uranium(0) shrapnel exposure and uranium(IV) oxide exposure is qualitativly and toxicologically different than hexavalent uranium(VI) uranyl compound exposure.

A two year study headed by Al Marshall of Lockheed Martin-funded Sandia National Laboratories analyzed some health effects associated with accidental exposure to depleted uranium during the 1991 Gulf War, but did not consider any nonradiological reproductive toxicity, developmental toxicity, or immuniological effects. 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 form Los Alamos and the New England Journal of Medicine .

The U.S. has admitted that there have been over 100 "friendly fire" DU victims, and an unknown number of inhalation exposure victims. Uranium combustion product inhalation exposure can result in substantial harm. No formal comparison can be made between the tactical advantages and the strategic drawbacks until the congenital malformation incident rate trend is known.

Further evidence against the role of DU used in combat in causing human illness comes from another war zone. If DU caused health problems in the Gulf War zone, it would be expected to do so in other warzones, but this has not proven true in early studies. In the Balkans, "independent investigations by the World Health Organization, European Commission, European Parliament, United Nations Environment Programme, United Kingdom Royal Society, and the Health Council of the Netherlands have all have discounted any association between depleted uranium and leukemia or other medical problems among Balkans veterans."

Legal status

In 1996 and 1997, the United Nations Human Rights Commission in Geneva, passed a resolution to ban the use of depleted uranium weapons. The Subcommission adopted resolutions which include depleted uranium weaponry amongst "weapons of mass and indiscriminate destruction, ... incompatible with international humanitarian or human rights law." (Secretary General's Report, 24 June 1997, E/CN. 4/Sub.2/1997/27)

According to the UN, the resolutions in 1996-97 were passed because the use of DU in ordinance breaches several international laws concerning inhumane weapons: it is not limited in time or space to the legal field of battle, or to military targets; it continues to act after the war; it is inhumane by virtue of its ability to cause prolonged or long term death by cancer and other serious health issues, it causes harm to future civilians and passers by (including unborn children and those breathing the air or drinking water); and it has an unduly negative and long term effect on the natural environment and food chain.

A UN report of 2002 states that the use of DU in weapons also is in potential breach of each of the following laws: The Universal Declaration of Human Rights; the Charter of the United Nations; the Genocide Convention; United Nations Convention Against Torture; the Third Geneva Convention; the Convention on Conventional Weapons of 1980; and the Chemical Weapons Convention. Treaties which were designed to spare civilians from unwarranted suffering in or after armed conflicts.

External links

Scientific bodies

United Nations

Scientific reports

Other

See also

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