carnes@gargoyle.UUCP (Richard Carnes) (07/17/86)
There is a detailed discussion of research on the toxicity of plutonium in an article in the Sept. 1976 *Bulletin of the Atomic Scientists* (pp. 27-37), by the biochemist John T. Edsall. This is ten years old, of course, but I think still worth reading. I append some brief excerpts, but first here is an interesting sidelight on the subject. In a 1983 book review, Victor Gilinsky of the NRC refers to an article by Bernard L. Cohen: Stung by Ralph Nader's retort that he was trying to "detoxify plutonium with a pen," Cohen describes his offer to inhale plutonium dust on the Johnny Carson show. The risk, he tells us (in a revealing comment) would be that faced by a soldier in *wartime*, a risk he thinks worth taking because such a demonstration would be an important service to his country. I am half inclined to agree with him. ... My own view is that there is one thing the public does understand, and that is when it is being patronized. It is tired of being patted on the head and told not to worry by men in white lab coats. Now from Edsall's article: Plutonium tends to hydrolyze under physiological conditions and form colloidal polymeric aggregates. These disappear rapidly from the blood and are chiefly deposited in the liver. "Soluble" plutonium, complexed with citrate or some other complex-forming ion, stays in blood much longer and becomes largely deposited in bone. [See W.J. Bair and R.C. Thompson, "Plutonium: Biomedical Research," *Science*, 183 (1974), 715-722.] ... Significant amounts of administered plutonium find their way to male and female gonads.... The concentration of plutonium from fallout in human autopsies averaged closed to 0.0005 nanocuries per gram of tissue in gonads [with implications for possible genetic damage].... Since direct evidence on the toxicity of plutonium in man is extremely scanty, the choice of the value of 40 nanocuries [as maximum permissible body burden] depended heavily on the extensive studies of production of malignant tumors in human bone by radium-226, and on the fact the both radium-226 and plutonium-239 are bone-seekers. The Utah studies on beagles indicated that plutonium-239 is more dangerous than radium, by a factor of 5 to 10, because it deposits on the bone in a more hazardous location.... Bair and Thompson suggest that the 40 nanocurie limit for plutonium may be several fold "less safe" than the 100 nanocurie limit for radium.... Recently several critics have proposed that the maximum permissible concentration of plutonium needs to be lowered by a substantial factor. The arguments advanced by various critics differ considerably, and I will try to explain them briefly here.... This is merely a brief look at some of the problems of plutonium in the environment. Obviously our ignorance is great, and we need to know vastly more in order to make sound decisions for the future. Plutonium and some higher actinides, being alpha emitters, are extremely powerful poisons. The official maximum permissible body burden ... is equivalent to 0.65 micrograms of this isotope, and to about 0.13 mcg of the mixed plutonium isotopes from a reactor. ... Plutonium has sometimes been compared in toxicity with some of the very powerful biological toxins, such as those of botulinus or tetanus.... They are, however, unstable like most proteins; boiled in solution, they lose activity in a few minutes, and even in the dry state they can be inactivated by ultraviolet light and other agents. Pu-239, on the other hand, remains a hazard for periods up to some 20 times its half life, or nearly half a million years.... [Bernard] Cohen has argued that plutonium is less dangerous than most people have supposed.... In general, however, I do not find Cohen's calculations reassuring. The situation is so full of complexities that are imperfectly understood, and the known toxicity of plutonium is so high, that I would not wish to base far-reaching policy decisions about plutonium on such preliminary calculations.... Clearly the prevailing standards of acceptable risk for plutonium are far more tolerant than those for food additives or pesticides. Does it make sense to maintain such widely divergent standards for different kinds of hazardous substances? ... The consequences of introduction of plutonium into the environment, on the very large scale required by an intensive nuclear power program, may be even more dangerous than we can now perceive. For material with a 25,000-year half life, they will certainly be irreversible. I believe that it is the better part of wisdom, and of our due responsibility to the generations who will follow us, to resist making such commitments.... I believe that the vigorous pursuit of these alternatives is far preferable to the risk of irreversible contamination of the environment that may well result from an economy heavily dependent upon plutonium and on the other actinides that would accompany it. [John T. Edsall] Richard Carnes
throopw@dg_rtp.UUCP (Wayne Throop) (07/21/86)
> carnes@gargoyle.UUCP (Richard Carnes)
A few problems with Richard's article.
First, and least important, Edsall hardly comes across as objective.
Second, "maximum permissible body burden" is hardly "the lethal dose".
Third, while it is true that it is much more difficult to detoxify
plutonium (as opposed to biological toxins), this was *NOT* the
assertion that is often made, that is, that plutonium is "the most toxic
substance". If you want to argue that plutonium is more hazardous for
various reasons *DESPITE* being less toxic, fine, argue away, but it is
misleading and incorrect to label it as "most toxic".
Lastly, Richard seems to make the leap from "some folks think we have
underestimated the hazard" to "MY GOD, WE'RE ALL GONNA DIE". It may
well be that many people are tired of being patronized, patted on the
head, and told "there, there, it's safe", but Richard might do well to
consider that some people have overdosed on alarmist propaganda, along
with those who have overdosed on polyannist propaganda.
--
#2: ... just think of what we'll have!
#6: A row of cabbages.
#2: But highly educated cabbages!
--- From "The Prisoner"
--
Wayne Throop <the-known-world>!mcnc!rti-sel!dg_rtp!throopw