military use of depleted uranium (du): potential health effects werner burkart professor for...

Military Use of Depleted Military Use of Depleted Uranium (DU): Potential Health Uranium (DU): Potential Health

EffectsEffects

Werner BurkartWerner BurkartProfessor for Radiation Biology and Environmental HealthProfessor for Radiation Biology and Environmental Health

based on a lecture by Burkart/Truckenbrod at an Int. based on a lecture by Burkart/Truckenbrod at an Int. Conference of Armed Forces Medical Services in Munich, Conference of Armed Forces Medical Services in Munich,

January 1999January 1999

Thursday, January 11, 2001 Werner Burkart 2

Use of Depleted Uranium (DU) in Use of Depleted Uranium (DU) in ammunitionammunition

• Gulf war: ~ 320 t• Kosovo conflict: ~ 10 t• Sarajevo safety zone: ~ 3 t

DU is radioactive and chemo toxicDU is radioactive and chemo toxic• As a result of its use is there a risk of health

effects?• Is there any evidence for these health effects ?


DU-Use in Kosovo (X Major Targets)DU-Use in Kosovo (X Major Targets)

Approx. 31,000 rounds or 9 tons in more than 100 missionsApprox. 31,000 rounds or 9 tons in more than 100 missions


Uranium in the Earth Crust: 0.3 – 3.0 g/tUranium in the Earth Crust: 0.3 – 3.0 g/t

Isotope U-234 U-235 U-238

Weight fraction in

%

0.0053 0.7100 99.2850

Half-life [years]

244,500 7.038 108 4.468 109

Specific activity [Bq/g]

231 106 80,011 12,445

Natural Uranium consists of three radioactive isotopes

U-235 and U-238 are the origin of two different decay chainsU-234 is a product of the decay chain of U-238


Feed, Product und Waste in aFeed, Product und Waste in aProcess for Uranium EnrichmentProcess for Uranium Enrichment

Feed Unat

(0.71% U-235) UF6

Enrichment Process

Enriched UF6 (3.6% U-235)

Waste: Depleted Uranium (DU) as Depleted UF6

(0.3% U-235)

Example: Pressurized Water Reactor


• DU is a waste product of uranium enrichment

• Presently there are 570.000 t of DU stocked in the USA

– The stockage of DU in steel containers is expensive

DU is cheap and available in large quantities


Definition and Properties of Definition and Properties of Depleted Uranium (DU) Depleted Uranium (DU)

• Content of U-235: 0.2 – 0.3 %• Low radioactivity• Practically pure -emitter

and -radiation field through daughter productsHeavy metal with high density: 18.9 g/cm3

• chemotoxic as most heavy metals• pyrophoric


Comparison between the Radiactivity Comparison between the Radiactivity of Uof Unatnat and DU and DU

Isotope U-234 U-235 U-238 Total

Activity in 1 mg Unat [Bq/mg Unat]

12.40 0.57 12.40 25.28

Activity in 1 mg DU [Bq/mg DU]

2.26 0.16 12.40 14.80

The activity of DU is 60% of that of Unat


Decay Chain of U-238Decay Chain of U-238

• DU contains 99.8 % U-238

• U-238 is not in radioactive equilibrium with its daughter radionuclides

• After few months equilibrium is reached between U-238, Th-234, Pa-234m

NuclideU-238

Th-234

Pa-234m

Half-life4.5 * 109 years

24.1 d

1.17 min

Type of Decay ()

()

U-234 2.5 *105 a

Pb-206 stable


Civilian Use of DUCivilian Use of DU

• Colour Glazing (red and yellow)• Steel alloys• Catalysts• Counterweights in fly wheels, fork lift trucks,

keel lines of ships• Ballast in aircrafts (the first 550 Boing 747)• Shield material for -radiation (better than lead)

Problem: Spontaneous ignition during the machining of the metal


Military Use of DUMilitary Use of DU

• Shielding in Tanks• Ammunition (first time in 1991, Gulf War, 320 t)

The high velocity of DU ammunition permits to penetrate the reinforced armoring of tanks

On hitting the target DU ignites, forming an aerosol of DU particles and/or larger fragments

Aerosol: the particle size and the quantity depends on the impact angle , velocity and burning temperature

Alternative to DU = Tungsten


Anti Tank DU AmmunitionAnti Tank DU Ammunition


Target Hit by DU AmmunitionTarget Hit by DU Ammunition


30 mm DU Rounds Found in Kosovo30 mm DU Rounds Found in Kosovo


ChemistryChemistry

Uranium is present in all crystal and mantel rocks in trace amounts. The average abundance is 2 – 3 mg/kg. Uranium in the environment is dominated by U (IV) and U (VI) oxides: Anoxic: U (IV) (UO2) insoluble, found in minerals (USiO4) Surface water, body fluids: typically U (VI) (UO3 divalent cation UO2

2+) Uranium used in penetrators and armor is in the zero oxidation state, which is thermodynamically unstable even at low temperatures. When exposed to the environment it will eventually oxidize (corrode). The oxidation liberates a large amount of heat.


Uranium metabolismUranium metabolism

Caveat: For more soluble uranium compounds intake is limited by consideration of chemical toxicity WHO limits for uranium intake: Drinking water: 2μg/LTolerable Daily Intake (TDI) 0.6μg/kg body weight Adsorption in the gut for dietary (monomeric) forms: 2 – 5 %even less for particulate and insoluble forms Most affected tissues: kidney; U binds to proteins (acute effects)

bone surface (radiation dose)liverred bone marrow

No enrichment in thyroid gland


Inhalation of different forms of uraniumInhalation of different forms of uranium

• Soluble forms cleared rapidly• Exotic (fired, “ceramic”?) forms may remain in lung, tracheobronchial lymph nodes for years (Fisher 1988) Hot particles → New CRP


Aerosol characteristicsAerosol characteristics

A considerable fraction of the DU ammunition can become Aerosols

Typical composition of an aerosol after hitting a solid target

ca. 61 % U3O8 Type S

ca. 18 % UO2 Type Sca. 20 % amorphous oxides Type F(Scripsick et al. 1984)

50 – 96 % of the aerosols can enter the lung

AMAD < 10 mAMAD = Activity Median Aerodynamic Diameter


Contamination of SitesContamination of Sites

Dust/fine dust: loose contamination inside and outside military objects

Fragments in soilcorroded DU is soluble

Remediation: elimination of the fragments, clean-up of the contaminated zones

Potential Radiation Dose ratesExternal: -Radiation, Th-234, Pa-234mDirect skin contact: 2mSv/h-radiation in tanks: 0.1 – 1.3 Sv/hInternal: -Radiation (U-238), and


Possible ways of incorporationPossible ways of incorporation

Inhalation of dust particles of different size and solubility

Ingestion through food, water,

swallowing of dust Wound contamination For military combat: shrapnel remaining in

the body


Uranium MetabolismUranium Metabolism

The uranium compounds can be classified according to their solubility and consequent transportability from the respiratory organs into the body liquids (ICRP 66)

Very slightly soluble ( S: low): UO2, U3O8

Moderately soluble (M: medium): UF4, UO3, UO4

Easily soluble (F: fast): UF6, UO2(NO3)2,UO2F2, UO2SO4

Uptake by the gastro-intestinal tract:f1 = 0.002: 0.2 % -”- (Moderately and very slightly soluble)

f2 = 0.02: 2.0 % will transfer to blood (soluble)


Health consequences of the Health consequences of the incorporation of DUincorporation of DU

Target organ

Chemotoxicity Kidney

Radiotoxicity Lung and bone


The lung as target organThe lung as target organ

The lung is the primary organ at risk from inhalation of Type S uranium compounds

The biological half-life of these compounds in the alveolar region of the lungs can be as long as 16 years

Complete retention by lymph nods is assumed Particles in the upper region of the respiratory

system move by mucociliary transport to the gastro-intestinal tract

0.2 % is reabsorbed by the intestine and the rest is eliminated via feces


Kidney and bone as critical target organs for Kidney and bone as critical target organs for soluble uranium componentssoluble uranium components

Inhaled uranium (Type F) will rapidly transfer to blood

98 % of ingested uranium (F) will be eliminated through the feces and 2% absorbed by the intestine

For both types of uptake U as a heavy metal, is chemotoxic for the kidney

(limit: 3 gU/g of kidney tissue, 0.9 mg/both kidneys)

Bone is considered critical for accumulated radiation dose


Model Predictions of the Uranium Content of Bone Model Predictions of the Uranium Content of Bone as a Function of Time after Injection into Blood for as a Function of Time after Injection into Blood for

Different AgesDifferent Ages


Annual limits for U-238 (StrlSchV, 1989)Annual limits for U-238 (StrlSchV, 1989)

Inhalation

Solubility F M S

[Bq] 3 * 104 1 * 104 6 * 102

[mg] 2.5 * 103 830 50

Ingestion

f1 = 0.02 f1 = 0.002

3 * 105 3 * 106

25 * 103 250 * 103


Results of Animal Studies (dogs)Results of Animal Studies (dogs)

The Solubility of the inhaled uranium compounds determines the target organ

CompoundLevel of exposureDuration of study

BodyConcentration

[mg U/kg]

OrganConcentration [g U/g]

Cumulative doseEffect

UO2

5.8 mg

5a

16Lung 2000

(6.6 Gy)Lung tumors

(4/13)

UF6

250-270 mg/m3 * 1h< 1a

0.67 Kidney 1.5Reversible

kidney damage

UO3 * xH2O * yNH3

80 – 160 mg/m3 * 1h< 1a

0.058 Kidney 0.6-3.5Reversible

kidney damage


Typical valuesTypical values

Soil (U-238) 0.3 – 11.7 mg/kg UNSCAR 1993

Air (U-238) 2.5 * 10-8 – 10-7 mg/m3 NCRP 1999

Water (Unat) 3 *10-2 – 2,100 g/L surface water

3 *10-3 – 2,000 g/L ground water

Drury et al. 1983

Food (U-238) 0.9 – 1.5 g/d UNSCAR 1977

Urine (U-238) 8 * 10-3 – 6 * 10-2 g/24d KWU 1999

Feces (U-238) 1.7 – 3.3 g/24d KWU 1999


Analytical MethodsAnalytical Methods(detection limits)(detection limits)

Urine (24h): ICP-MS (nBq - Bq U-238)

-Spectrometry (0.5 mBq/d)

Fluorimetry (13 mBq/L)

Urine (spot): For 1 g Creatinine

Feces (24h): ICP-MS

Hair: ICP-MS, treatment is necessary (long-term information)

Nails: ICP-MS, treatment is necessary (long-term information)

Lung counter In-vivo methods

Detection limit: 100-300 Bq of Unat


Studies on 33 Gulf-War veteransStudies on 33 Gulf-War veterans

Cohort of US Soldiers wounded by DU or present in a vehicle hit by DU ammunition (friendly fire)• The study started 3 years after the war• Blood parameters: no significant alteration

Uranium in urine

18 veterans with fragments [g/g Crea.]

15 veterans without fragments [g/g Crea.]

1993/94 4.47 0.03

1995 6.40 0.01

DU fragments in the body release uranium which shows up in urine (increased mobility of uranium with time)


Available Epidemiological InformationAvailable Epidemiological Information

There are no studies on populations exposed only to uranium

Uranium is only a minor contributor to naturally or artificially elevated radiation exposures

Indirect Risk Evaluation Experimental radiobiological information Mechanistic considerations


In Search of a Definition of the Gulf War In Search of a Definition of the Gulf War Syndrome ISyndrome I

Tiredness 20.5%

Skin rash 18.4%

Headache 18.0%

Muscle and joint 16.8%pain

Loss of memory 14.0%and other symptoms

Shortage of breath 7.9%

Sleeping problems 5.9 %

Diarrhea and other 4.6%disturbances of thegastro-intestinal tract

Other symptoms 3.6%

Chest pain 3.5%

With no problems 12.3%

A Guide to Gulf War Veterans Health, 1998 Continuing Medical Education Program

The 10 most frequently reported problems by Gulf War veterans (N = 52.835)


In Search of a Definition of the Gulf War In Search of a Definition of the Gulf War Syndrome IISyndrome II

No diagnosis26.5%

Musculosceletal and25.2%

Connective tissues

Disturbance of the 15.1%Psychological equilibrium

Respiratory system 14.3%

Skin tissues13.5%

Digestive system 11.4%

Nervous system 8.3%

Circulatory system 7.1%

Infectious diseases 7.0%

Injuries and poisoning 4.7%

Urogenital system 3.4%

Neoplasm 0.4%

A Guide to Gulf War Veterans Health, 1998 Continuing Medical Education Program

Distribution of diagnoses (N = 52.835 veterans)


Other Agents Discussed in Connection with Other Agents Discussed in Connection with the Gulf War Syndromethe Gulf War Syndrome

Fire fumes, soot, various harmful chemicals Napalm Several toxins Vaccines Pesticides Insecticides Protective substances against chemical

weapons


SummarySummary

No acute risk Theoretical cancer risk due to DU contamination

much smaller than that from natural radiation Complications due to perception (emotional,

psychological, stress-related) Possible future actions:

Radio-ecological assessment, dose estimates Health-effects assessment Occupational hygiene: monitoring before/after

deployment, documentation of DU activities, doses, health statistics

military use of depleted uranium (du): potential health effects werner burkart professor for...

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