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[Previous entry: "Global Reach III"] [Main Index] [Next entry: "Oil for Food; who's in charge?"] 22 April 2003: "Do you realise self-righteous ignorance has a half-life of over 4.5 billion years?"
With yet another US military action having taken place involving the use of depleted uranium (DU) munitions, the scaremongering which has become commonplace every time these munitions are discussed (and I use the term very loosely) is once again in full swing. A prime example is an opinion piece in the Seattle Times, "Depleted-uranium weapons should be banned" by Glen Milner, a Seattle resident and a member of the Ground Zero Center for Nonviolent Action (in Poulsbo, WA). Yet, as citizens raise their concerns over the magnitude of the problems related to DU weapons, which are more evident every year, the U.S. military maintains that no threat exists. How can this be?Only two things are more evident every year:
As the WHO Fact Sheet points out, DU has about 60% of the radioactivity of natural uranium. This doesn't sounds very reassuring if you don't take into account that natural uranium is itself not sufficiently radioactive to be used in, say, a nuclear power plant*. Uranium has to be enriched before it's suitable for that purpose, and that entails more than doubling the U235 content (which is the highly radioactive isotope); ideally, you'd want increase the proportion of U235 even further. Hopefully, you're starting to get a perspective on how radioactive DU actually is. More on that later. Milner: DU weapons are prized by the U.S. military for their superior armor-piercing ability. In 1991, 320 tons of DU were used in Iraq. The Pentagon says the U.S. fired around 10,800 DU rounds, close to three tons, in Bosnia in 1994 and 1995. According to NATO, more than 31,000 rounds, about 10 tons, were fired in Kosovo in 1999.Sounds scary, doesn't it? All those thousands of rounds, and all those metric tons of DU (FYI, 1 metric ton is 2,205 lb). But as this opinion by a group of experts from EU countries points out, 10 metric tons (22,050 lb) of DU fill a volume of about half a cubic metre (~17.5 cubic feet); this is, of course, due to the fact that DU is amazingly dense. It might also be noted that those many thousands of rounds fired in Bosnia and Kosovo were all PGU-14/B Armor Piercing Incendiary rounds fired by A-10 "Warthogs" ("Ugly, but very well hung") using their 30mm GAU-8/A "Avenger" Gatling cannon, which have a cyclic rate of fire of 3,900 rounds per minute, i.e. 65 rounds per second (though it should be pointed out the standard "combat mix" of ammunition is four rounds API to one round High Explosive Incendiary, so only 80% of an A-10's ammunition load is DU). When you know this, you'll understand why an estimated 90-95% of those rounds fired missed their targets. Which brings me to the following point. Milner: When a depleted-uranium projectile impacts a solid surface, the pyrophoric properties of this heavy metal ignite, producing intense heat, resulting in an aerosolized radioactive release as the projectile quickly burns through the armor. The residue of this firestorm is an extremely fine ceramic uranium dust that can be spread by the wind, inhaled and absorbed into the human body, and absorbed by plants and animals, becoming part of the food chain.Sounds scary, right? But as I said, an estimated 90-95% of the DU rounds used in the former Yugoslavia missed their targets and went straight into the soft ground, and therefore did not turn into the dust Milner describes. (It should be noted that a single PGU-14/B contains approx. 302 grams of DU; the rest of the round is titanium—to be exact, 75% by mass—and an aluminium jacket. The numbers Milner cites correctly reflect the mass of DU used, though not the mass of the rounds, which would be some four times as high. I doubt Milner is aware of the difference.) The WHO Fact Sheet has the following to say regarding absorption of DU: Okay, so the most hazardous exposure to DU occurs when one inhales the dust (even though, as the numbers show, at most slightly over 2% of the material inhaled will be reatined in the body for more than a few days); this much is clear. But what does that mean in concrete terms? From the EU expert opinion: The worst scenario envisaged in the preliminary assessment made in October 1999 by UNEP was inhalation (at the site and times of an explosion of a DU penetrator) of up to 100mg inhaled DU. The committed effective dose would correspond to a maximum of about 10 mSv (using the current ICRP models, and assuming ICRP default Type S absorption), and the highest organ dose calculated to be to the lungs, at about 80 mSv (for adults). [...] The resulting doses (internal or external) are unlikely to cause any deterministic effects, and are far below the minimal doses at which lung and lymph node fibrosis and leukocytopenia have been observed in animals. It is noted that organ doses fom DU inhalation are delivered at a very low rate, whereas deterministic effects appear rather for acute high doses.To put things in perspective, 1 mSv (millisievert) is reckoned to be the normal dose of natural background radiation most people are exposed to in a year. A chest X-ray inflicts 0.02 mSv; a head CT scan inflicts 2 mSv; an upper GI exam inflicts 3 mSv; an abdominal CT scan inflicts 10 mSv (the same as a lungful of DU dust). So according to UNEP, to be in danger of developing radiation sickness from exposure to DU, one would have to make a habit of standing next to tanks at the moment they are being destroyed by a DU round, and a frequent habit at that. Dude, if you make a habit of that, DU is the least of your worries; bluntly put, the chances of your living long enough to develop lung cancer, let alone leukemia, are negligible. So how about long-term environmental exposure? The EU expert opinion: Measurement by the US Army showed that the highest exposures from gamma radiation are likely to arise in a DU-armoured vehicle carrying DU ammunition. Measurement have shown that driving such a vehicle for 1000 hours gives a dose (i.e. about 1 mSv) similar to the average annual external dose from natural background radiation.1,000 hours is 41 days and 16 hours in one stretch; alternatively, it's a 40-hour working week for about half a year. So if you spent an entire year manning an M1A2 Abrams 40 hours a week (with two weeks' holiday), you'd run up 2 mSv on top of your regular exposure. But your regular exposure to background radiation would be down, because—due to its density—DU blocks radiation (which is why it's used as radiation shielding in medical equipment and containers for transporting radioactive material), so at the end of the year, you'd have run up 2.89 mSv. Now compare that to the (immediate) 10 mSv in the UNEP "worst-case" scenario, which isn't enough to cause "deterministic effects." But that's "regular" DU. As Milner points out: In 2000, the U.S. Department of Energy admitted that depleted uranium used in Kosovo was contaminated with "transuramic" [sic] (heavier than uranium) fission wastes from inside nuclear reactors. Munitions used were spiked with plutonium, neptunium and americium.Unfortunately for Milner, the WHO Fact Sheet states: Spent uranium fuel from nuclear reactors is sometimes reprocessed in plants for natural uranium enrichment. Some reactor-created radioisotopes can consequently contaminate the reprocessing equipment and the DU. Under these conditions another uranium isotope, 236U, may be present in the DU together with very small amounts of the transuranic elements plutonium, americium and neptunium and the fission product technetium-99. However, the additional radiation dose following intake of DU into the human body from these isotopes would be less than 1%.Emphasis in bold mine. "Fearsome," my codling. In light of the aforegoing, one may reasonably conclude that DU does not constitute a radiological health hazard. Nevertheless, as Ronald Bailey points out (though Glen Milner does not), DU is a heavy metal, and is chemically toxic. The kidneys in particular are at risk, since in the event of inhalation and subsequent absorption into the bloodstream, they would bear the burden of filtering the DU out of the the blood. However, the EU expert opinion notes that: The UNEP report states that the inhalation of 100 mg DU might lead to acute chemical toxicity.The operative word here being "might." And again, this is the "worst-case scenario" regarding exposure to DU dust. Moreover, it should be noted that armour-piercing munitions need to be made of high-density material to be effective, and that entails some sort of heavy metal. In other words, any material suitable for the job is going to be chemically toxic to about the same extent—perhaps more so—than DU. And if you're going to try to ban heavy metals in warfare, you can start with the use of lead in small arms ammunition. Uh yeah, good luck with that. If one is concerned about radiological hazards, one might do better to be concerned about the disposal of radiological waste from medical applications, especially radioactive isotopes of cobalt, strontium and cesium, all of which are considerably more dangerous than DU. In fact, these are three of the materials which are transported in DU-lined containers, and the primary candidates for use in "dirty bombs," which DU, for all the rounds supposedly littering Iraq, Bosnia and Kosovo, is not. PS. As a matter of clarification, I don't consider myself sufficiently informed to form a definite opinion, one way or the other, on the existence of "Gulf War syndrome" or "Balkans syndrome"; however, any genuine medical problems suffered by Coalition, UNPROFOR or NATO personnel have a number of possible causes, of which DU is not the most obvious. For example, the town of Lukavac in Bosnia was referred to by Dutch troops as "stoflongoord" (freely, "emphysemaville") as early as 1994 (before the NATO air campaign) because of the pollution caused by a local factory. Thus, if you found yourself confronted with a former UNPROFOR member who had spent time in Lukavac and was now suffering from a pulmonary disorder, you would have to obtuse in the extreme to attempt to link that disorder to DU. * - Murray in Canada writes to explain that you can use natural uranium, though not in light water reactors, which are standard in the US. Canadian CANDU reactors, Murray explains, use heavy water as a moderator; since heavy water absorbs fewer neutrons, the uranium doesn't need to be quite that radioactive. Thanks for pointing that out, Murray. |
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