Information on uranium ammunition (Depleted Uranium, DU)

The purpose of this text is to provide some factual information on the subject of uranium ammunition (uranium projectiles, depleted uranium, DU). The focus is not on military aspects. Rather, we are concerned with questions of possible health hazards to people who are or have been in places where uranium ammunition has been used.

After some information on the function, effect and previous use of uranium ammunition, physical, chemical and radiobiological principles are presented which can help in the assessment of possible health hazards from uranium.

1 What is uranium ammunition and how does it work?
2 Use of uranium ammunition
3 Physical, chemical and radiobiological aspects of uranium ammunition
3.1 Occurrence of uranium and natural uranium content in humans
3.2 Isotopic composition
3.3 Physical properties of uranium; uranium alloy "U-3/4Ti"
3.4 Uranium compounds, dusts, aerosols
3.5 Health (physiological) effects of uranium
3.5.1 Chemical-toxic effects
3.5.2 Radio-toxic effects
3.5.2.1 External radiation exposure
3.5.2.2 Internal radiation exposure
4 Malignant diseases and genetic damage caused by radiation exposure
5 Evidence from urine samples?
6 Links on the topic (without guarantee and without comment)

A projectile is designed to destroy a target. If the projectile contains a high-density material, its destructive effect (its penetrating power) is largely based on its kinetic energy (kinetic energy). This energy can be transferred to the target particularly effectively if the pressure (the force per surface area) on impact of the projectile is as high as possible. This is achieved by using fast bullets made of materials with the highest possible density, such as uranium, whose density is approx. 70 % greater than that of lead.

When a uranium projectile hits a target such as a tank, the kinetic energy of the projectile is largely converted into thermal energy. This leads to a large amount of heat being generated. In addition to the mechanical destruction in the area surrounding the hit caused by the penetrating force (hence the term "penetrator") of the projectile, the tank's fuel and ammunition are set on fire, rendering it unusable. The temperatures and forces generated on impact are so high that the projectile melts and in some cases atomises. The resulting uranium dust ignites due to its pyrophoric properties and intensifies the destructive effect of the projectile. The military objective of the projectile is thus achieved.

However, uranium projectiles also have a side effect. The melting, atomisation and ignition of the uranium produces uranium particles and uranium oxides, which are released into the surrounding air as aerosols and dust. People who are at the site of an impact inhale these particles and dust or ingest them with their food. As uranium is always radioactive, so are the aerosols and dust. Consequently, in addition to the chemical exposure to the heavy metal uranium, the people affected are also exposed to radioactive radiation. Both can lead to illness, depending on the amount of uranium ingested.

According to NATO, uranium ammunition was used in the Gulf War and in the Balkans; uranium ammunition was also used in the Iraq war in 2003. According to information from the US Department of Defence, a total of around 330 tonnes of uranium was fired from various weapons systems during the Gulf War. Most of this came from the "GAU-8" on-board cannon (30 mm calibre) of the US fighter aircraft "A-10": approx. 784,000 projectiles with a total of approx. 230 tonnes of uranium.

According to information from the German Ministry of Defence, 31,000 uranium projectiles were fired from the same fighter aircraft in Kosovo and 10,800 uranium projectiles in Bosnia/Herzegovina. This corresponds to a uranium quantity of approx. 11.5 tonnes.

Here are pictures of the "A-10" fighter aircraft, the "GAU-8" gun (30 mm calibre) and the uranium projectile (GAU-8 ammunition, type PGU-14/B). The total length of the projectile including the rear propellant charge is approx. 29 cm, its total mass approx. 0.69 kg. The uranium core is located in the front part of the projectile, the actual projectile with a length of approx. 14.5 cm and a diameter of approx. 1.5 cm, and has a mass of approx. 0.27 kg. The muzzle velocity of the projectile is approx. 1,010 m/s, corresponding to approx. 3,640 km/h.

In the affected areas, the use of uranium ammunition has produced considerable quantities of uranium dust and uranium-containing aerosols, which are repeatedly released into the surrounding air through turbulence and can therefore pose a danger to people in the area. In contrast, a possible hazard from radiation from uranium deposited on the ground or from unexploded ordnance lying there is negligible.

Uranium (chemical symbol: U) is a heavy metal and a natural component of the earth's crust. Its abundance is around 2.3 grams/tonne (= 2.3 g/1000 kg, corresponding to 2.3 ppm (parts per million)). As a result, air, drinking water, soil and food contain traces of natural uranium. The average uranium concentration in the air is around 0.04 ng/m³ (0.04 billionths of a gram per cubic metre). With an average daily breathing rate of an adult of approx. 20 m³ of air/day, around 0.8 ng (nanograms; billionths of a gram) of uranium per day enters the body through breathing. Depending on dietary habits and region, an adult ingests around 1 µg to 4 µg (micrograms; millionths of a gram) of uranium per day with food and drinking water. A significant proportion of this is excreted in the faeces, only a small proportion is absorbed by the body. This results in an average uranium content in the body of an adult of approx. 30 µg to 60 µg.

Natural uranium is uranium that occurs in nature. It is a mixture of different uranium isotopes. It consists of 99.28 % uranium-238, 0.72 % uranium-235 and contains traces of uranium-234 (0.0054 %).

Depleted uranium( DU) is a waste product from the production of nuclear fuel for nuclear power plants. It typically consists of 99.8 % uranium-238 and 0.2 % uranium-235 and contains practically no uranium-234. If it is not obtained from natural uranium but from spent fuel elements from nuclear power plants, it may also contain traces of plutonium-239.

Enriched uranium is used in nuclear power plants (NPPs). It is needed there to maintain a chain reaction. Enrichment (physical process) increases the proportion of uranium-235 compared to natural uranium. Enriched uranium for nuclear power plants consists of around 3% U-235 and around 97% U-238 - Highly enriched uranium is used in nuclear bombs. There, the proportion of uranium-235 is approx. 90 %.

Uranium is a silvery-white, soft metal. Its melting point is approx. 1130 °C, its boiling point approx. 3930 °C. Due to its high density of approx. 19 g/cm³, it is a heavy metal. For comparison: the density of water is 1 g/cm³, that of iron 7.9 g/cm³ and that of lead 11.3 g/cm³. A litre bottle filled with water therefore weighs 1 kg and filled with uranium 19 kg.

The high density of uranium is the reason for its use in bullets: with the same size (same calibre) as conventional ammunition, they have a considerably higher mass and therefore a considerably greater penetrating power. The penetrating power is additionally increased by hardening the material, which can be achieved by adding small amounts of titanium. The uranium alloy "U-3/4Ti", which contains around ¾ per cent titanium by weight, is therefore predominantly used in uranium bullets.

Uranium is an actinide. This includes all elements with atomic numbers between 89 (actinium) and 102 (nobelium), whereby only elements up to atomic number 92 (uranium) occur in nature in significant quantities. All actinides are metals and radioactive. The most important representatives of the actinides, namely thorium-232, uranium-235, uranium-238 and plutonium-239, are alpha (α) emitters. Their radioactive decay therefore always releases α radiation; a small amount of gamma (γ) radiation is also produced.

In a finely dispersed state (dusts), actinoids are pyrophoric, i.e. self-igniting in air.

The physical half-life of a radioactive substance indicates the time within which its radioactivity has decreased by half. The activity is expressed in becquerels (Bq). One becquerel corresponds to one radioactive decay per second. Closely linked to the half-life of a substance is its specific activity. It indicates the activity of 1 g of a substance, i.e. how many radioactive decays take place per second in 1 g of the substance. The shorter the half-life, the greater the specific activity. The following table contains some examples of different uranium isotopes, uranium isotope mixtures and two isotopes of plutonium and thorium.

The most important uranium compounds include its oxides: the yellow UO₃, the brown-black UO₂ and the green-black U₃O₈. In addition, the colourless uranium hexafluoride (UF₆), which is used in the enrichment process.

When a uranium projectile hits a target, most of its kinetic energy (kinetic energy) is converted into thermal energy. This causes the projectile to melt or atomise, producing uranium particles and uranium oxides. These form dusts or small particles(aerosols) that are released into the surrounding air and can be inhaled by people in the vicinity or ingested with food.

The chemical-toxic effect of a substance is understood to be the harmful effect on health based on its chemical properties. Like lead, cadmium, mercury or plutonium, uranium is a heavy metal. heavy metal. Heavy metals and their compounds are toxic. In particular, they cause damage to the kidneys and liver.

The World Health Organisation (WHO) recommends limiting uranium intake from food and drinking water to 0.5 μg per kilogram of body weight per day; i.e. approx. 35 μg per day for a body weight of 70 kg. The actual average uranium intake is around (1 - 4) μg per day, depending on the region and eating habits.

The radio-toxic effect of a substance is the harmful effect of radioactive radiation released by the substance. Radioactive radiation is ionising radiation because it ionises atoms and molecules in the body, i.e. it can remove electrical charge from them. The damaging effect of radioactive radiation is based on this ionisation and the formation of radicals (decomposition of water into the chemically particularly aggressive components H and OH), which ultimately manifests itself in cell changes. The greater the radiation dose absorbed by the body, the greater the damage. This in turn is primarily determined by the quotient (absorbed radiation energy) : (absorbing mass).

The radio-toxic effect of uranium-238, the main component of depleted uranium, is primarily due to its α-radiation. The radio-toxic effect is comparable to the radio-toxic effect of plutonium-239 or other radioactive heavy metals with α-decay, such as radium-226 or thorium-232, for the same amount of activity.

With high specific activity, such as plutonium-239, the radio-toxic effect is the main hazard; chemical toxicity, on the other hand, is negligible. In the case of low specific activity, e.g. uranium-238, the chemical-toxic effect must be taken into account in addition to the radio-toxic effect.

To assess the radio-toxic effect of α-radiation, a distinction must be made between external (external) and internal (internal) radiation exposure.

External radiation exposure occurs when a person is in the vicinity of a radioactive substance and is exposed to radioactive radiation from outside. Since α-radiation can be easily shielded and therefore only has a range of a few centimetres even in air, external radiation exposure from uranium-238 only plays a minor role. This is different for β- and γ-emitters, as β- and especially γ-radiation have a considerably greater range. If, for example, a radioactive substance is deposited on the ground, the external radiation exposure from uranium-238 is around 1,000 times lower than that from the β- and γ-emitters caesium-137, which was released in large quantities in the Chernobyl accident, for the same ground activity (given in becquerels per square metre, Bq/m²) and the same exposure time for humans.

Internal radiation exposure occurs when a person has absorbed a radioactive substance into their body (incorporation). The radioactive radiation is then released in the body. Radioactive substances are mainly absorbed through the air we breathe (inhalation) and food and drinking water (ingestion).

Depending on their solubility, radioactive substances ingested with food and drinking water enter the bloodstream via the gastrointestinal tract and can thus spread throughout the body.

Depending on their particle size, radioactive substances ingested with the air we breathe initially remain in the respiratory tract (bronchi, lungs), from where they also pass into the blood, again depending on their solubility.

In the case of α-emitters such as uranium-238 or plutonium-239, the internal radiation exposure is the dominant source of the radiation dose. For example, for the same amount ofinhaled activity(given in becquerels, Bq), the radiation dose from uranium-238 is about 3,700 times greater than that from the β- and γ-emitters caesium-137. A key reason for this is easy to understand: The radiation dose (given in sieverts, Sv) depends primarily on the quotient [absorbed radiation energy E] : [absorbing mass m]. Since α-rays have a high energy (a few MeV) and at the same time a short range in tissue (a few 10 µm), a lot of energy is absorbed in small areas of tissue. The quotient E:m and thus the radiation dose is therefore high.

The radiation dose and thus the risk of radiation-induced cancer or leukaemia or genetic damage increases with the duration of exposure to radiation. The longer a radioactive substance remains in the body, the more radiation energy is absorbed by the tissue, i.e. the higher the radiation dose. As the physical half-life of the α-emitters discussed here is very long compared to the life expectancy of a human being (approx. 4.5 billion years for uranium-238), it is of decisive importance how long the so-called biological half-life of the ingested substance is. This is the time within which half of a substance once ingested is excreted from the body (mainly in the urine). It depends crucially on the route (respiration or ingestion), the chemical form (determines the solubility) and the physical form (particle size) in which the substance was absorbed. The biological half-lives of uranium for the various absorption routes and types range from a few days to a few years. The radiation can therefore have a very long effect on the organism under certain circumstances.

All these aspects are taken into account when determining the so-called dose factors. These dose factors can be used to calculate the radiation dose (expressed in sieverts) that a quantity of radioactivity (expressed in becquerels) once absorbed by the body will lead to over the course of a lifetime (so-called 50-year follow-up dose for adults and 70-year follow-up dose for children).

As a first rule of thumb, it can be stated that the dose factors for radiobiologically significant α-emitters such as uranium-238, uranium-235, plutonium-239, radium-226 or thorium-232 are all in the same order of magnitude. In this respect, a certain amount ofuranium-238 activityis similarly harmful to health as the same amount ofplutonium-239 activity. The fact that plutonium-239 is nevertheless often described as "particularly dangerous" or even as the "most toxic substance" is due to its specific activity. This is about 180,000 times greater for plutonium-239 than for uranium-238 (see table in this section), which is mainly due to the half-life of 24,000 years, which is about 185,000 times shorter than that of uranium-238. In a given mass of plutonium-239, therefore, around 180,000 times more radioactive decays take place per second than in a mass of uranium-238 of the same size.

Inhaling the tiny mass of around 40 nanograms (40 ng, 40 billionths of a gram) of plutonium-239 is therefore sufficient to exceed the limit value permitted for academic appointments under the Radiation Protection Ordinance. limit value of 100 becquerels for inhalation. The chemical toxicity of such a small amount of heavy metal is negligible. However, the radiation dose caused by the 100 becquerels of plutonium-239 is not. It amounts to approx. 15 mSv (15 millisieverts; 15 thousandths of a sievert). This is more than 6 times the natural annual radiation dose, which in Germany is around 2.3 mSv.

For 100 becquerels of uranium-238, 8 milligrams (8 mg, 8 thousandths of a gram) would have to be inhaled and for 600 becquerels, the limit value of the annual activity intake for inhalation of uranium-238, a quantity of approx. 48 milligrams. These are quantities at which, in addition to the resulting radiation dose of approx. 20 mSv, the chemical toxicity of uranium as a heavy metal already plays a significant role.

As a second rule of thumb, the dose factors for inhalation are about 100 times greater than those for ingestion for the α-emitters discussed here. The isotopes mentioned are therefore particularly dangerous for humans when they are inhaled.

Once the radioactive substances have entered the bloodstream via the gastrointestinal tract or the lungs, they can accumulate in certain organs. In the case of uranium, as with plutonium, the accumulation organs are primarily the bones (approx. 60 %), the liver (approx. 15 %) and the kidneys (approx. 10 %). The radioactive radiation released there can lead to a radiation dose in the organs that can cause cancer. In addition and above all, lung cancer can develop, as larger dust particles in particular can become lodged in the lung tissue and then release their radioactive radiation there over a long period of time. For all the cancers mentioned, they typically only occur 20 to 30 years (latency period) after exposure to radiation.

Accumulation in the bones results in long-term irradiation of the bone marrow, i.e. the haematopoietic system. This can cause leukaemia be triggered. According to current knowledge, such leukaemia typically occurs 2 to 10 years(latency period) after exposure to radiation. - According to the World Health Organisation (WHO), the "normal" number of cases of leukaemia occurring per year in the group of 20-45-year-old adults is around 50 cases per million.

Finally, radioactive irradiation of the body's own gonads can cause genetic damage which can manifest itself in malformations or diseases in the next generation.

It will never be possible to establish a causal link between the exposure to radioactive radiation and the development of cancer or leukaemia or genetic damage with absolute certainty in individual cases, as the triggers of these diseases (radiation, toxins, genetic defects, etc.) do not leave a fingerprint. However, it is undisputed that the risk of leukaemia, cancer or genetic damage increases as the radiation dose increases. It should therefore be investigated whether, for example, the soldiers in the Gulf War, the Bosnia mission or the Kosovo war were exposed to increased radiation levels from radioactive uranium dust and thus whether there is a possibility of radiation-induced cancer or leukaemia or genetic damage.

If the soldiers inhaled such dusts in significant quantities, the uranium absorbed by the body is only slowly excreted from the body due to its sometimes long biological half-life. It can therefore be reliably detected in urine samples of those affected for years after exposure.

As explained above, an adult ingests around 1 µg to 4 µg of uranium per day with food and drinking water, depending on dietary habits and region. Around 95 % of this is excreted in the faeces. About 5 % is absorbed by the body. Depending on age, a certain amount of this is excreted in the urine each day: in a 20-year-old, around (20 - 30) ng (nanograms; billionths of a gram), corresponding to an activity of around (0.25 - 0.38) mBq (millibecquerels, thousandths of a becquerel). A 40-year-old excretes about twice this amount, a 60-year-old about three times this amount.

With today's technology (especially mass spectrometry), it is no problem to detect an additional uranium intake, especially with the air we breathe, compared to the natural uranium intake with food and drinking water through increased uranium excretion in the urine. Such a test should be offered to all those affected. It is advisable because it can also dispel doubts or uncertainties. Either the thesis of "zero risk" publicly proclaimed by the Federal Government is confirmed, or there are indications that possible dangers have been too hastily dismissed.

In 2001, the GSF (today: Helmholtz Zentrum München - Research Centre for Environment and Health) presented the results of tests on people who had been deployed in Kosovo. According to the GSF, the urine uranium concentrations measured in these people were all within the normal range (see list of links).