Difference between revisions of "Depleted uranium toxicity"
Revision as of 06:50, 16 February 2018
- Uranium is an alpha-emitting, radioactive heavy metal that occurs naturally in nearly all rocks and soil. Natural uranium is made up of the three naturally occurring isotopes of uranium namely 234U, 235U, and 238U. Naturally occurring uranium deposits are over 99% 238U. You eat, drink, and breather natural uranium on a daily basis.
- Health hazards of natural uranium have been studied extensively since 1940s. Health impact of Depleted Uranium (DU) has been studied since the early 1970s.
- Enrichment is the industrial process by which natural uranium is separated into enriched uranium which has an increased percentage of 235U and depleted uranium which has a decreased percentage of 235U.
- DU is a byproduct of the enrichment process.
- DU has 40% less radioactivity than natural uranium. It has a specific activity of 0.33 microCi/g.
- DU has the same chemical properties as naturally occurring uranium, it simply has different ratio of isotopes of 234U, 235U, and 238U.
- DU health effects will be the same as for natural uranium because the toxicity is primarily due to the chemical toxicity rather than radiotoxicity.
- United States Armed Forces have used depleted uranium in the manufacture of ammunition, armor, and aircraft.
- DU's high density, self-sharpening quality and pyrophoricity make it a good choice for projectile munitions.
- DU's density makes it a good armor choice.
- DU's density also makes it a good choice for counterbalance weights used in aircraft and on helicopter rotors.
|'||Natural Uranium||Depleted Uranium|
|Isotope||Concentration of isotope||Concentration of isotope|
Routes of exposure
- Inhalation - minor route of exposure for general population. Major route for occupational population. On average in US individual daily intake of uranium is 0.007 micrograms by inhalation.
- Oral - predominant route of exposure for general population through ingestion of food and drinking water. Average daily intake of uranium in US is 1.9 micrograms by ingestion.
- Dermal - unlikely route of exposure for general population. Potential route of exposure for military service members.
- DU is poorly absorbed following inhalation, oral, or dermal exposure route.
- Amount absorbed heavily dependent on the solubility of the compound.
- <0.1-6% of uranium is absorbed following oral exposure.
- 67% of uranium in blood is filtered in the kidneys and leaves body in urine within 24 hours. Remainder is distributed to tissues primarily bone, liver, and kidney.
- Retention half-time for uranium in bone is 70-200 days.
- Retention in body skeleton (66%), liver (16%), kidneys (8%), other tissues (10%)
- Alpha emitter thus not serious external radiation hazard. Alpha radiation has poor penetrating ability. Direct contact with bare DU for 250 hours is necessary to exceed annual occupational exposure limits.
- Internal exposure via inhalation, ingestion, wound contamination or retained fragments warrants some concern.
- Chronic exposure by inhalation is potential radiologic hazard to the lung and thoracic lymph nodes.
- Genotoxicity, mutagenicity and reproductive effects are being studied.
- Kidney dysfunction main chemically-induced effect of uranium
- Can develop tubulopathy or renal tubular acidosis
- DU is a heavy metal like lead, tungsten or nickel which can damage the kidneys when present in large amounts.
- DU exposure normally does not result in any symptoms as small amounts are quickly passed
- DU make cause impairment of the kidneys if exposure is significant in short term
- Alpha radiation exposure
- Heavy metal toxicity
- Patients who feel they have been exposed to high levels of DU should be evaluated
- Assess the following in patient:
- Circumstances : date, time, route of exposure, amount
- Evidence of wound or embedded fragments?
- Has patient had any prolong skin contact i.e. through keeping of a souvenir?
- Provide medical examination:
- Determine kidney function (blood urea and creatinine)
- Conduct urine analysis
- Complete blood count
- Chest x-ray if history suggestive of significant inhalation exposure
- Test for uranium exposure if history suggest proximity to source or large exposure or any abnormalities on about routine examination
- Check beta-2 microglobulin in 24 hour urine to check for tubulopathy
- Check urine uranium level if elevated than 24 hour excreted DU level should be accessed including isotope-specific methods to identify ratios of isotope of uranium
- Acute exposure manage as would for any heavy metal exposure
- Remove patient from exposure
- Externally decontaminate if residue present on patient
- Base further treatment on symptoms observed
- Renal tubulopathy treatment which needs to be applied early prior to fixation of uranium in the skeleton to be truly effective
- Sodium bicarbonate perfusion to alkalinize urine
- Consider heavy metal chelation therapy
- Monitor renal function
- Most cases of exposure have no permanent effect
- Likelihood to develop any health effects is low
- If exposure is via inhalation and significant amounts of insoluble uranium compounds deposited in lungs than patient will need long-term surveillance/follow-up
- Agency for Toxic Substances and Disease Registry (ATSDR), Toxicological Profile for Uranium (Update), February 2013.
- McDiarmid, M.A. (2001). Depleted uranium and public health. BMJ, 322(7279), 123-124.
- U.S. Army Environmental Policy Institute (AEPI). (June 1995). Health and Environmental Consequences of Depleted Uranium Use in the U.S. Army: Technical Report.
- Department of Defense. (August 4, 1998). Health Effects of Depleted Uranium - Fact Sheet.
- U.S. Army Environmental Policy Institute, (AEPI). (June 1994). Health and Environmental Consequences of Depleted Uranium Use by the U.S. Army, Summary Report to Congress.
- World Health Organization (WHO), Guidance On Exposure to DU- For Medical Officers and Programme Administrators, 2001.
- World Health Organization (WHO), Depleted Uranium: Sources, Exposure and Health Effects, 2001.
- World Health Organization (WHO), Depleted Uranium Fact Sheet, revised January 2003.