Depleted Uranium — the Science

My stimulative old friend wrote me to ask about depleted uranium, enclosing a recent article by Larry Johnson from the Seattle Post-Intelligencer called “Use of Depleted Uranium Weapons Lingers as Health Concern.” ¹  Apparently this piece is now being bruited about among antiwar leftist circles as supposedly yet more dirt they've dug up on guess who (his initials are GWB).  Still these streams of doom articles are effective in raising doubts in the minds of many people.  My friend asked:

Do you have an opinion on if the depleted uranium stories are true, or just another exaggeration by anti-war groups?  If true, wouldn't using it near highly populated areas be an avoidable extra burden on the Iraqis?

Best I can make out, the depleted-uranium agitation by the antiwar left is more than just exaggeration, it's pretty much invented whole cloth — garbage, in other words.  You recall the naive old saying, “Where there's smoke there's fire”?  From what I've seen of propaganda mills blasting away full bore (full of lies), I'm much more taken by the comeback, attributed to John F. Kennedy, I believe:  “Where there's smoke, you'll usually find somebody running a smoke-making machine!”

Depleted uranium has two possible modes of instigating biological damage — ionizing radiation due to the fact that it's a radioactive metal, and biological toxicity due to the fact that it's a “heavy” metal.  Regarding the first of these, radioactively “depleted uranium” is basically as little radioactive as it's possible to be and still be radioactive and not inert.  This may sound like a quibble, but the half-life of uranium-238, the major radioactive component of depleted uranium (since it's been “depleted” of other uranium isotopes) is 4.5 x 10⁹ (i.e., billion) years (not "109" years as news pieces have erroneously reported).  In other words, over the entire 4.6 billion year age of the Earth, the quantity of uranium-238 on this planet has decreased by only half.  That is barely detectably radioactive at all, on the human timescale.

Even when it does decay, virtually all (> 99.99%) of uranium-238 follows the mode of alpha decay (emission of a Helium-4 nucleus), which cannot penetrate beyond a couple of inches in air and is stopped cold by sheet of paper.  Contrast with gamma rays (high energy electromagnetic radiation emitted by some radioactive decayers) which can penetrate through feet or meters of lead and are highly destructive to biological tissue.

The possibility of heavy-metal toxicity by uranium is potentially of greater scientific import.  That, though, is fundamentally no different than toxicity due to say lead, which has traditionally been used (without environmentalists' extraordinary complaints) as bullets on battlefields for centuries.

Rather than theorizing about either of these two possible toxicological modes of action, however, medical researchers have sought hard to see if any medical damage can be actually detected.  Several hundred U.S. solders were exposed to depleted uranium during Gulf War I: from shrapnel pieces left embedded in their bodies, to vaporized aerosols accidentally inhaled, to other possible means of exposure.  Because they're American, as well as the subsequent “Gulf War Syndrome” controversy following the first Gulf War, these people have been carefully studied.  Beyond that, hordes of folks who worked in the uranium industry have been closely watched medically over the years.  Plus the U.N., E.U., Britain's Royal Society, and others have repeatedly investigated the effects of depleted uranium in Bosnia, Kosovo and Serbia as a result of its use in the wars that NATO and the U.S. have fought there.  The results of all these studies are practically the same:  essentially no adverse medical effects, even less than what might have been expected due to uranium's heavy metal character.

Don't take my word for it.  In a recent general media article entitled “Assessing America's nuclear detritus,” after detailing (what I would consider to be only semi-reasonable) concerns many in Europe and elsewhere have about depleted-uranium munitions, Deborah Blum in the Baltimore Sun writes: ²

Should DU bullets be classified in this company [along with other admitted toxicological horrors]?  Rationally, of course, there's no comparing anti-tank munitions with the legacy of the two atomic bombs dropped on Japan, “Fat Man” and “Little Boy.”  Some remnant tons of slightly radioactive metal should barely flicker on the environmental threat meter.  If the rest of the world would just be more rational, we wouldn't be having this discussion.

That kind of exasperated reasoning approaches the position of the Pentagon and, in fact, many independent scientists.  Robert L. Park of the American Physical Society is downright sarcastic on the question:  “I always figured it would be a lot better to be shot with a uranium bullet than a dum-dum — it should make a good clean hole.  Physicists don't spend much time worrying about natural uranium, and DU is even less radioactive by about 40 percent.”  […]

It [military advantages of depleted uranium] also means we can end battles quickly, surely a good thing.  If by doing that, DU bullets save lives and if the radiation is a minor issue, it's fair to ask why other people dislike them so much.  For one thing, radiation is only part of the problem.  Like other heavy metals, such as lead, depleted uranium is chemically toxic.  Absorbed by the body, heavy metals can damage kidneys, break down nerves and cause chemically induced cancers.  The Pentagon actually considers this a greater risk.  Military doctors have been watching gulf war veterans, braced for those illnesses.  But they haven't uncovered such signs of evil.

In the 12 years of testing, they've found no such poisoning, no radiation-linked cancers, no patterns of uranium-sparked disease.  U.N. studies conducted in Kosovo and Bosnia came up similarly empty on health effects.  That doesn't mean these are benign materials.  Studies in cell cultures and microorganisms show even low-level toxicity does harm at the cellular level, that even wimp radiation kills and deforms cells.  A few studies have suggested DU might be worse than passive metals such as lead, that the radiation and toxicity could work together to cause genetic damage.  Perhaps.  So far, though, only the Iraqis have noted severe effects in humans, from birth defects to cancers, but they have also refused to allow the United Nations to independently verify the claims.

Could those pre-war (Gulf War II), Saddamite Iraqis making the charge perhaps have had an ax to grind in this affair?  Just maybe?  Could the leftists who've so avidly taken up the cry also?

There have, of course, been many articles in the general media, of varying degrees of quality, on the subject of depleted uranium.  Numerous bloggers have also posted on the subject, and as with the general media, with varying degrees of quality and veracity.  I'll mention only a couple of these, two posts by Steven Den Beste on USS Clueless. ^{3, 4}

The major purpose of this article, however, is to point to (wrap ups of) the major scientific literature on the issue of depleted uranium.
 

National Defense Research Institute.  The U.S. National Defense Research Institute has done a review of the scientific literature with regard to Gulf War illnesses, of which its Volume 7 pertains to depleted uranium.  Among its conclusions, for example, I will emphasize three: ⁵

• […]  there are no peer-reviewed published reports of detectable increases of cancer or other negative health effects from radiation exposure to inhaled or ingested natural uranium at levels far exceeding those likely in the Gulf.

• Large variations in exposure to natural uranium in the normal environment have not been associated with negative health effects.

• […]  no increased morbidity or frequency of end-stage renal disease has been observed in relatively large occupational populations chronically exposed to natural uranium at concentrations above normal ambient ones.
   

United Nations Environment Programme (UNEP).  Nor are these conclusions limited to United States agencies.  On the contrary, the United Nations Environment Programme (UNEP) did an investigation, in which it dispatched teams of researchers to Kosovo to inquire after the effects of depleted uranium in that conflict.  A report on the UNEP's findings, presented last year, appears in the journal Science (requires subscription or pay-per-view).  Here are pertinent quotes: ⁶

The team, led by physical chemist Pier Roberto Danesi, former director of the International Atomic Energy Agency's (IAEA's) laboratory in Siebersdorf, Austria, confirmed that some patches of soil from known impact sites in Kosovo are tainted with DU.  But the amounts, the team maintains, are so tiny that the radioactivity poses virtually no cancer risk.  Moreover, Danesi's group found no evidence of elevated plutonium levels in the soil.  Their findings jibe with those of other bodies, including the U.K.'s Royal Society and the European Union, that have surveyed the DU literature.  “There is a consensus now that DU does not represent a health threat,” says Danesi.  The latest findings, asserts radiochemist Corrado Testa of the University of Urbino in Italy, “confirm that there is no risk from DU.”

They found that in the most contaminated places, a few milligrams of soil could contain hundreds of thousands of DU particles — but still not a high enough concentration to elevate cancer risk, Danesi says.  Plutonium levels in the Kosovo soil — about 1 becquerel per kilogram — accorded with global levels of fallout from atmospheric nuclear tests.  For comparison, soil levels in the Alps, near Salzburg, are nine times as high, thanks to Chornobyl.  ”As far as the plutonium is concerned, you could feed this soil to someone and he'd be fine,” Danesi says.  His team will elaborate on its findings in companion articles in the December [2002] issue of the Journal of Environmental Radioactivity.  …  [M]aintains Testa, “for me this is a false problem.  We could be spending money on more urgent problems” — toxic solvents, heavy metals, and organic pollutants, to name a few, he says.
 

World Health Organization (WHO).  The World Health Organization has done its own reviews of the (considerable) scientific information available on the health effects of uranium, depleted or un.  Here's a selection of its results: ⁷

• In a number of studies on uranium miners, an increased risk of lung cancer was demonstrated, but this has been attributed to exposure from radon decay products.  Lung tissue damage is possible leading to a risk of lung cancer that increases with increasing radiation dose.  However, because DU is only weakly radioactive, very large amounts of dust (on the order of grams) would have to be inhaled for the additional risk of lung cancer to be detectable in an exposed group.  Risks for other radiation-induced cancers, including leukaemia, are considered to be very much lower than for lung cancer.

• Erythema (superficial inflammation of the skin) or other effects on the skin are unlikely to occur even if DU is held against the skin for long periods (weeks).

• No consistent or confirmed adverse chemical effects of uranium have been reported for the skeleton or liver.

• No reproductive or developmental effects have been reported in humans.
   

The European Commission.  The European Commission of the E.U. has issued its own comprehensive evaluation of the situation with regard to depleted uranium.  Here are its basic conclusions: ⁸

• […]  On the basis of available information, it is concluded that exposure to DU could not produce any detectable health effects under realistic assumptions of the doses that might be received.  Moreover, in view of the fact that committed doses from incorporated DU build up over a lifetime and in view of the minimum latency period of cancer induction, such effects could not occur during the first few years after incorporation as a result of radiological exposure.

  This conclusion applies in particular to leukaemia: while the latency period for leukaemia is shorter than for solid cancers, uranium accumulates very little in blood forming organs such as bone marrow.  Following inhalation of insoluble uranium the calculated risk of leukaemia is orders of magnitude lower than the risk of lung cancer induction.

  The possibility of a combined effect of exposure to toxic or carcinogenic chemicals and to radiation can not a priori be excluded but there is no evidence to support this hypothesis either.  Under the considered scenario, exposures to DU give low doses, comparable to the natural background.  Hence there is no reason to believe that chemicals may change the magnitude of the potential radiation effects.

• Possible contamination of drinking water must be considered since it is a possible pathway of exposure if very large amounts of DU are buried in soil […].  A generic assessment yields nothing however but very low doses resulting from drinking water.  […]
   

The Royal Society.  The Royal Society of the U.K., Britain's Academy of Sciences, has done its own study, discussed here in the journal Science (requires subscription or pay-per-view). ⁹  The study “concludes that health risks from DU radiation are ‘for the most part low.’  There are possible exceptions, however, including a likely higher risk of lung cancer in tank crew members who inhale the ‘impact aerosol’ created when a DU shell pierces their vehicle's armor.”  Note that this is primarily a danger for tank crews, who are likely killed anyway directly from the penetration fireball.

The Royal Society's study can be reviewed in its entirety here.  Some of its major conclusions: ¹⁰ 

• Except in extreme circumstances any extra risks of developing fatal cancers as a result of radiation from internal exposure to DU arising from battlefield conditions are likely to be undetectable above the general risk of dying from cancer over a normal lifetime.  This remains true even if our estimates of risk resulting from likely exposures are one hundred times too low.

• The extreme circumstances will apply only to a very small fraction of the soldiers in a theatre of war, for example those who survive in a vehicle struck by a DU penetrator, or those involved in cleaning up struck vehicles.  In such circumstances, and assuming the most unfavourable conditions, the lifetime risk of death from lung cancer could be about twice that in the general population.

• Any extra risks of death from leukaemia, or other cancers, as a result of exposure to DU are estimated to be substantially lower than the risks of death from lung cancer.  Under all likely exposure scenarios the extra lifetime risks of fatal leukaemia are predicted to be too small to be detectable.  […]

• For those returning to live in areas where DU munitions were deployed, including peace-keepers, the inhalation uptakes from resuspended DU are considered to be unlikely to cause any substantial increase in lung cancer or other cancers.  The estimated lifetime risk of fatal lung cancer is about one in a million, although there could be high risks for some individuals with worst-case intakes of DU due to higher levels of local contamination.  Estimated risks of other cancers are at least 100-fold lower.  […]
   

National Institutes of Health/National Academy of Sciences.  The U.S. Institute of Medicine of the National Institutes of Health in conjunction with National Academy of Sciences has produced a massive study on the “Health Effects Associated with Exposures During the Gulf War,” of which its Volume 1 (a 24 megabyte file, in PDF format) exhaustively examines depleted uranium, among other things.  The NIH/NAS report arrives at similar conclusions to all the others: ¹¹ 

• The committee concludes that there is limited/suggestive evidence of no association between exposure to uranium and lung cancer at cumulative internal dose levels lower than 200 mSv or 25 cGy.  However, there is inadequate/insufficient evidence to determine whether an association does or does not exist between exposure to uranium and lung cancer at higher levels of cumulative exposure.

• The committee concludes that there is limited/suggestive evidence of no association between exposure to uranium and clinically significant renal disfunction.

• The committee concludes that there is inadequate/insufficient evidence to determine whether an association does or does not exist between exposure to uranium and the following health outcomes:  lymphatic cancer; bone cancer; nervous system disease; non-malignant respiratory disease; or other health outcomes (gastrointestinal disease, immune-mediated disease, effects on hematological parameters, reproductive or developmental dysfunction, genotoxic effects, cardiovascular effects, hepatic disease, dermal effects, ocular effects, or musculoskeletal effects).
   

Centers for Disease Control (CDC).  The Agency for Toxic Substances and Disease Registry (ATSDR) at the Centers for Disease Control (CDC) of the U.S. Department of Health and Human Services (HHS), put it most concisely in its Public Health Statement for Uranium:  “No human cancer of any type has ever been seen as a result of exposure to natural or depleted uranium.” ¹²
 

Journal Nature.  Among other recent scientific articles discussing depleted uranium, perhaps typical is this one from the British journal Nature (requires subscription or pay-per-view).  In the midst of arguing that “toxicology research should urgently appraise its performance and join mainstream biomedical science,” the authors (a Briton and Italian) express the point that “there is no evidence for radiological or chemical carcinogenic risk [from depleted uranium in, e.g., Kosovo] at any conceivable level of exposure.” ¹³
 

In these studies, depleted uranium gets off the hook from both a theoretical and a practical, what-are-the-observed-results? point of view; thus it's very difficult to take any leftist-fanned-up commotion with regard to this matter seriously.  They're just lying, I'm sorry to say.
 
 

References

¹ Larry Johnson, “Use of Depleted Uranium Weapons Lingers as Health Concern,” Seattle Post-Intelligencer, 2003.08.04.

² Deborah Blum, “Assessing America's nuclear detritus,” Baltimore Sun, 2003.06.08.

³ Steven Den Beste, “Non weapons grade,” USS Clueless, Stardate 20020929.0138.

⁴ Steven Den Beste, “More on depleted uranium,” USS Clueless, Stardate 20021224.1126.

⁵ A Review of the Scientific Literature As It Pertains to Gulf War Illnesses, Volume 7: Depleted Uranium, by Naomi H. Harley, Ernest C. Foulkes, Lee H. Hilborne, Arlene Hudson, C. Ross Anthony; RAND Report, National Defense Research Institute, 1999.

⁶ Richard Stone, “New Findings Allay Concerns Over Depleted Uranium,” Science, Vol. 297, No. 5588 (2002.09.13), p. 1801 (requires subscription or pay-per-view),

⁷ Depleted Uranium, World Health Organization, revised 2003.01.  (See Fact Sheet No. 257 linked to on that page.)

⁸ Depleted Uranium, Opinion of the Group of Experts established according to Article 31 of the European Treaty, chartered by the European Commission, report delivered 2001.03.06.

⁹ Science, Vol. 292, No. 5521 (2001.05.25), p. 1465 (requires subscription or pay-per-view).

¹⁰ Health hazards from depleted uranium munitions, The Royal Society, 2002.05.

¹¹ Gulf War and Health, Volume 1: Depleted Uranium, Sarin, Pyridostigmine Bromide, Vaccines, Edited by Carolyn E. Fulco, Catharyn T. Liverman, and Harold C. Sox, Committee on Health Effects Associated with Exposures During the Gulf War, U.S. Institute of Medicine, National Academy Press, 2000; pp. 14-16.

¹² Public Health Statement for Uranium, Agency for Toxic Substances and Disease Registry (ATSDR), CAS #7440-61-1, 1999.09.

¹³ Marcello Lotti and Pierluigi Nicotera, Toxicology: A risky business, Nature, Vol. 416, p. 481 (2002.04.04); doi:10.1038/416481a (requires subscription or pay-per-view).
 
 

UPDATE:  2003.08.21 15:15 UT.  Made some formatting changes.

UPDATE:  2003.08.22 13:00 UT.  Added a paragraph (alpha emission from U-238).

UPDATE:  2003.08.27 13:00 UT.  Eugene Volokh at The Volokh Conspiracy has linked to Impearls' article.  Armed Liberal at Winds of Change picked the link up from him.  Bargarz in turn noticed the link there.  (Bargarz is one of those bloggers who has posted extensively on depleted uranium before.)  Donald Sensing at One Hand Clapping posted a link to the article.  Bill Herbert at COINTELPRO Tool also linked to it.  Roger Schlafly at Roger's View posted a link too.

CPO Sparkey at Sgt. Stryker's linked to the piece, with the added comment:

Back when I was in the Navy, I had a liberty buddy who worked the CWIS mounts and spent a lot of time in the magazine surrounded by all that 20 mm Armor Piercing Discarding Sabot (APDS), Depleted Uranium (DU) sub-caliber penetrator ammunition.  When we returned from our deployment he promptly went on leave flying home to the east coast (the Enterprise was home ported in Alameda CA at the time).  Like a typical sailor (or college student) he took his laundry home for Mom, only this time he forgot to turn in his personal dosemetry (TLD).  Upon his return he turned in his TLD and it was then discovered that his round trip, cross country flight, resulted in more exposure than his previous 6 months living in a room fill with several tons of Depleted Uranium.

Clayton Cramer also linked to it, commenting:

Nice Summary of the Depleted Uranium Tempest in a Teapot.  It's here, by Michael McNeil.  My only quibble might be that he mentions at one point that the radiation from depleted uranium doesn't have much penetration.  That's true.  Outside of your body, it's no big deal at all — alpha particles won't even penetrate clothing.  If it ends up inside your body, even the limited penetration has some potential to do some damage.  Overall, however, I am not surprised that there is consensus that depleted uranium is an oversold problem.  It is the left's latest attempt at creating a crisis upon which to destroy Bush for overthrowing their favorite thug.

Clayton is correct that alpha radiation occurring within a living organism is a totally different bear from alpha radiation simply impacting the skin of that organism (which typically blocks it without harm).  Recall, however, that depleted uranium's rate of alpha emission is still subject to U-238's extraordinary 4.5 billion year half-life.  Thus the proper question to ask is whether that alpha emission occurs at a rate which produces damage that is detectable — and the answer which comes back from all the studies is that it does not.  That answer is obtained, as it should be, not only from theoretical considerations but also from practical medical investigations of people and patients, including detective-like following and connecting of dots with regard to places where exposures to toxicologically questionable materials could have occurred, versus where individual people were who have been reported sick.

CPO Sparkey reminds us in his tale that cosmic rays — far more powerful than alpha particles — continually sheet through our bodies, even at sea level (though less in magnitude at lower altitudes).  Any other radiation, even if originating within one's own cells, which quantitatively constitutes only a small fraction of that constant cosmic bombardment, isn't going to produce any noticeable effects.  As the European Commission put it in their study above, “exposures to DU give low doses, comparable to the natural background.”  ⁸