|Date:||22 Jan 2002 18:54:44 -0000|
|Subject:||RE: [CPEO-MEF] DU munitions|
Susan - You have an interesting way of looking at things. DU may have less U235, and more U238, but that doesn't mean it's not radioactive. It's just less radioactive. Even if it were 100% depleted of U235, which is never the case, by the way, it would still give off 1/10 the dpm of the original stuff, given an equal amount of U238 left behind. In other words, U238 is 1/10th as radioactive as U235. Not 0% radioactive by comparison, 10% by comparison. (This number is based on the half-life, which is only an order of magnitude, 10x, different.) I don't know what you do, but I am a toxicologist working on environmental pollutants. I look at net toxicity, which means potency x concentration. If the potency is 1/10th, but the amount distributed is 10X (or more, because of this mistaken belief that U238 is "not radioactive" and therefore it seems to be being liberally sprinkled in places where little radioactivity was before), then you end up with the same net dpms over a given period of time. Off the top of my head, I do not recall the difference in specific activity of the two isotopes, but I do not recall that the net energy was all that different for every disintegration. Thus, please stop railing about DU being not radioactive. It is radioactive, just 10x less so, pound for pound of U235 and U238. The problem with this is that while most exposures are expected to be "low dose radioactivity", it's also a chronic exposure for folks who live in DU-bombed, or DU-contaminated areas. If you look through the literature, there is not a whole lot understood about the health effects of long term, low dose radioactive exposures. Most toxicologists have focused on "bomb-like" high dose acute exposures, mostly because that's what we as a world people have had most experience with. (In 25 years, however, I expect there to be a huge number of papers on long term low dose exposure. Unfortunately, it's today's exposees who will be the subjects of those papers.) Further, Uranium is still a non-essential heavy metal. Heavy metals have both common mechanisms of action and actions unique to certain metals. In common are the interference with Calcium metabolism and calcium-mediated physiological actions (of which there is a multitude, including secretion of hormones and neurotransmitters and cytokines). Also in common are the storage into bone and kidney, usually resulting in kidney toxicity in the long-term. There's also the potential for interference with protein structure and function due to the tendency for heavy metals to bind to sulfurs, which can disrupt disulfide bridges which control three dimensional protein structure. Due to the first and the third mechanisms above, IF U can get into the immature brain (which is not well protected in utero and shortly after birth), U (U238 or U235) has the potential to disrupt a host of critical processes controlling brain development. Now, there are tidbits in the literature here and there (mostly there, and mostly a long time ago) that indicate that if we just looked for the long-term low dose effects of heavy metal toxicity from U, even as DU, it will probably be there. Given all that, I really think that we (as the human race) need to be a lot more careful about our profligate use of DU. We don't know enough, but what we do know says it's likely to be a lot more dangerous, in a sub-lethal way, than your reply implies. And given it's long half-life, human life, and animal life, will have to live with our (ab)use of DU for thousands of generations to come. Diane Henshel
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