Talk:Polonium

Article changed over to new Wikipedia:WikiProject Elements format by maveric149. Elementbox converted 12:28, 10 July 2005 by Femto (previous revision was that of 06:33, 9 July 2005).

Information Sources

Some of the text in this entry was rewritten from Los Alamos National Laboratory - Polonium. Additional text was taken directly from the Elements database 20001107 (via dict.org), Webster's Revised Unabridged Dictionary (1913) (via dict.org) and WordNet (r) 1.7 (via dict.org). Data for the table was obtained from the sources listed on the main page and Wikipedia:WikiProject Elements but was reformatted and converted into SI units.

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Archives

/Archive 1: mostly Nov 2006, regarding polonium poisoning and toxicity.

LD50

The toxicity information seems inconsistent to me. LD50 doses are normally in mg per kg body weight, as is the Sv unit (equivalent absorbed energy per kg of tissue). But the article currently reads:

The fatal dose (LD50...) for acute radiation exposure is generally about 4 Sv [21]. One Bq of 210Po ... causes a radiation dose of 0.51 µSv if ingested, and 2.5 µSv if inhaled [22]. ...a fatal 4-Sv dose can be caused by ingesting 8 MBq (200 microcurie), about 50 nanograms (ng), or inhaling 1.6 MBq (40 microcurie), about 10 ng.

I can't make sense of this. An absolute amount of radiation (I mean radioactive substance) in Bq is translated into a dose per unit of body weight (Sv), which is then translated into an absolute toxic amount (50 ng). I'm not changing the article since I might be misunderstanding something here and I suppose there are plenty of knowledgeable people reading this article these days. Han-Kwang 23:01, 1 December 2006 (UTC)

Here's the logic: (a) One Bq is not an amount of radiation, it is a quantity of a radioactive material that produces on average one decay per second. For any particular substance, activity in Bq is directly convertible to mass in grams; for 210Po the conversion constant is 166 TBq per gram, according to ref 22. (b) Activity in Bq is related to dose in Sv through an empirical number called the the "committed effective dose eqivalent" (CEDE), which is the amount of damaging radiation exposure in Sv that would be caused to a typical human by ingesting/inhaling one Bq of the substance. As I understand it, the CEDE takes into account how long it takes for human kidneys to expel the substance, how it distributes among organs, and how sensitive each of these organs is, as well as the type and energy of radiation. For ingestion of 210Po, the CEDE is 5.14E-7 Sv/Bq, according to the same ref. I tried to avoid introducing the concept of CEDE, to keep the text simple; was this a mistake?

Anyway, this calculation was my own, and I'll readily volunteer that it should be criticized as original research because it combines information from different sources to draw conclusions. Thus it would be preferable to find a single source, of comparable reliability to the original sources here, that already contains the acute human LD50 in grams etc. That may be hard to come by, however (any volunteers for human LD50 experiments?), and rats/mice may get a lower radiation dose per ingested amount by excreting it much faster than humans, so using only rat/mouse data is not necessarily an improvement. Here is a place to look up the mouse LD50, though: "The toxicity of polonium 210 in mice. I. The thirty day LD50, retention, and distribution." FINKEL MP, NORRIS WP, KISIELESKI WE, HIRSCH GM. (1953), Am J Roentgenol Radium Ther Nucl Med. 70(3):477-85. PMID: 13080529. (Note that the same calculation as I did has since popped up in several places on the web, including an expert media advisory so don't use web sources younger than Nov 29 - they may have read it on Wikipedia...)

By the way, I'm removing the existing rat toxicity reference (Rencováa et al.): the dose taken from that reference (8.7 ng/kg) was fatal to all 44 rats in that experiment, thus it does not represent the LD50 at all, but a much higher and more fatal dose. It is only an upper bound on the LD50, and thus not informative enough to quote here. --mglg_(talk) 03:47, 4 December 2006 (UTC)

Ah, with the CEDE it makes much more sense. I'm personally not very picky regarding original research, as long as the reasoning is verifiable. Han-Kwang 21:25, 5 December 2006 (UTC

I am only a radiation biologist and not a specialist in radiation toxicology, but I am pretty sure that the calculation of the amount of polonium which you need to cause a fatal dose leads you to a figure of mass in gram or nanogram and NOT in nanogram "per kg body weight". This "per kg body weight" is only used for chemicals. See also, http://www.mathed.tw/wd2/schoolwiki/wp/p/Polonium.htm, where they calculate 0.12 microgram for a lethal dose of 10 Sv. The mean lethal dose of 4.5 Sv (and that should perhaps also be said in your article) is a dose which causes 50% lethality, i.e. of 100 people exposed to 4.5 Sv, 50 will die. Further, you need to clarify the "minimal lethal dose" at the end of the paragraph. I suspect it is a mean lethal dose for non-instantaneous exposure, but then it should be 0.089 microgram (NOT 0.89), about 1.7 times more than the 50 nanogram in the instantaneous case. I do not know where your reference 29 has it from, and I cannot find anything like it in your reference 30. Tsp110 (talk) 12:56, 10 January 2008 (UTC)

Trivia : Exam

Our professor included an exerpt from this article. Was a fun test. We had to work out the mass it would take to kill 1 st russian ex-spies. PoorLeno 20:17, 2 December 2006 (UTC)

Decays to ...

84-2=82 Thallium, presumably. The Litvinenko article seems bogged down in 210Po becoming Lead, which presumably Thallium eventually does, but not soon. Worth adding that to the article? Midgley 00:42, 4 December 2006 (UTC)

Not worth adding, because it is incorrect. Atomic number 82 is lead. Thallium is 81. --mglg_(talk) 02:29, 4 December 2006 (UTC)

Chemically toxic?

How could anybody possibly know (or care) whether polonium is chemically toxic "with poisoning effects analogous with tellurium", given that the LD50 of tellurium is 20 mg/kg, meaning that a fatal dose for an adult human would be more than a gram, whereas nanogram quantities of polonium will kill you by its radiation? Unless somebody provides a source, I suggest we drop the statement about chemical toxicity. --mglg_(talk) 19:27, 12 December 2006 (UTC)

It is still a matter of speed, radiation can/could take way longer than the chemical, so I still believe it is important. --Dirk Beetstra ^{T C} 19:30, 12 December 2006 (UTC)

Certainly needs a good reference, since it seems absurd on its face. I would expect that a dose that is sufficient to be damaging chemically would kill you by radiation extremely rapidly. In general, an acute radiation dose of a few Sv causes bleeding from the gut within minutes[1]. A one-gram dose (approximately the LD50 of tellurium metal) of 210Po would cause 40 million times more radiation exposure than that. --mglg_(talk) 21:41, 12 December 2006 (UTC)

I think that you are right in the case of polonium, but still chemical poisoning is also one of the properties of the metal (but then, most of the metals in that corner of the periodic table are toxic, if I am correct. I don't know enough about toxicology to know if one could get administered 1.6 grams of polonium and die from that dose (calculation does not hold perfectly, it is an LD50, and not tested on humans), instead of the radiation. Maybe other isotopes than 210? But in all cases, a reference would be nice.

Oh, I am thinking now .. how do they know the LD50 is 20 mg/kg (they measured it, right?). So one must be able to survive significant amounts without being killed by radiation (or at least a rat or a rabbit must have survived many milligrams of it). Time to call in an expert. --Dirk Beetstra ^{T C} 22:02, 12 December 2006 (UTC)

The LD50 of 20 mg/kg was for tellurium, not Polonium. --mglg_(talk) 22:32, 12 December 2006 (UTC)

OK, since no convincing argument to the contrary has been voiced, I am dropping the statement about chemical toxicity. --mglg_(talk) 19:24, 3 January 2007 (UTC)

Industrial alternatives

The article does a great job of explaining that industrial alternatives are readily available, to avoid using this dangerous substance merely to supress static electricity. Too good! The reader would tend to not notice that nonetheless Po-210 is in wide use for such trivial purposes, with no current measures to restrict/phase out. Can someone come up with some real facts and figures about annual industrial use? See The Smoky Bomb Threat by Peter D. Zimmerman NYT December 19, 2006 http://www.nytimes.com/2006/12/19/opinion/19zimmerman.html 69.87.193.121 15:00, 19 December 2006 (UTC)

tobaccodocuments.org has several documents on the occurence of polonium in the food & tobacco pipeline. The industrial alternative for polonium rich fertilizer - used a few decades before lung cancer was first seen by our family doctors ( it was so rare that med students used to travel to neighboring hospitals to see what was probably going to be the only case they would ever see ) - of course is polonium free fertilizer ( took a million PHDs and $billion to figure this out ).159.105.80.141 (talk) 20:27, 22 February 2008 (UTC)

Residential Radon and Po

Can the article indicate that radon emitted from granite lurks in the basements of houses in granite areas. It is dangerous because Po, as the breakdown product of radon, attaches to dust particles and is inhaled and lurks in the lungs? This is mentioned in the Po Talk page but not in the article. === Vernon White (talk) 22:02, 25 December 2006 (UTC)

Actually, the "Chronic effects" section already states that The general population is exposed to small amounts of polonium as a radon daughter in indoor air; the isotopes ²¹⁴Po and ²¹⁸Po are thought to cause the majority of the estimated 15,000-22,000 lung cancer deaths in the US every year that have been attributed to indoor radon. Feel free to add a little more (sourced) detail if you think it is called for. --mglg_(talk) 19:24, 3 January 2007 (UTC)

So if ²¹⁴Po and ²¹⁸Po are the natural isotopes of Polonium shouldn't they be in the info box with their natural abundance rather than the synthetic isotopes. --Henrygb 10:50, 9 March 2007 (UTC)

Inaccuracy?

"A milligram of 210Po emits as many alpha particles per second as 5 grams of 226Ra." When I do a little math, I get about 4.215 grams of radium-226 for every milligram of polonium-210. I'm not an expert in radiation, since that unit was awhile ago in chemistry, so if somebody wants to check my work, go right ahead.

Half life is 1602 years, 584730 days for radium 226. Half life is 138.376 days for polonium 210.

for radium, 584730 = ln(2)/k

k = ln(2)/584730 = 1.18541409*10^-6

for polonium, 138.376 = ln(2)/k

k = ln(2)/138.376 = .0050091575

for radium, ln(A) = -k*1 + ln(1) after one day, starting at 1 gram

e^(-(1.18541409*10^-6)*1 + ln(1))

A = .9999988146 grams left after one day

for polonium,

e^(-.0050091575)*1 + ln(1))

A = .9950033674 grams left after one day

Out of one gram at the beginning,

in one day, 1.18541336*10^-6 g reacts in radium

in one day, .0049966326 g reacts in polonium

(.0049966326 grams polonium per day/ 1.18541336*10^.6 grams radium per day) = (x grams polonium per day/ 1 gram radium per day)

x = 4215.097263 grams Po per day for every 1 gram Ra per day react, units cancel, Po is 4215.097263 times more radioactive.

For the same level of radioactivity, 4215.097263 grams of radium must react for every 1 gram of polonium.

(1 gram Po / 4215.097263 gram Ra) = (.001 grams Po / x grams Ra)

To have equivalent levels of radiation, 4.215097263 (4.215 when rounded to significant figures) grams of radium must react for every one milligram of polonium. BirdValiant 05:45, 31 March 2007 (UTC)

Your calculations look correct, but I think you are forgetting something. From the half-life numbers, it is true that, in one second, 4215 times as many nuclei of Po-210 decay as of Ra-226. However, you also need to account for the fact that Ra-226 nuclei are heavier than Po-210 ones by a factor of approximately 226/210. Thus, the activity from one milligram of polonium corresponds to that of 4215 * 226/210 mg = 4.536 g of radium. Rounded to one significant digit (as seems appropriate for illustration purposes), that does indeed come to 5 g. I'm changing the article back, unless someone finds a further flaw in the above. Hqb 11:25, 19 August 2007 (UTC)

Tobacco smoke

On 3 January, 2008, anonymous editor 142.179.116.145 changed the sentence "Polonium has been found in tobacco smoke from tobacco leaves grown with phosphate fertilizers." to "Polonium has been found in tobacco smoke from tobacco leaves grown with phosphate fertilizers, though similar amounts occur in everything from cherries to human tissue." [2] No additional sources were cited, and I haven't found any confirmation of this elsewhere. I find the "human tissues" claim hard to believe without a specific citation. The "cherries" claim is irrelevant because people don't inhale cherries into their lungs. Finally, the phrase "everything from cherries to human tissue" is meaningless and inherently POV. Cherries and human tissue are completely disparate and it isn't possible to talk about the range of "everything" between them. Without a source to tell us what, exactly, is in this supposed range, I don't see a way that the claim can be rephrased besides "although cherries and human tissue contain comparable amounts", which seems to give undue weight to the significance of cherries and human tissue as standards for comparison. I am therefore removing the claim. mistercow (talk) 16:16, 17 March 2008 (UTC)

Possible stable isotopes

The Isotope OE83Bi209 is given as the last (Stable) atomic isotope. However it only has 43 extra neutrons whereas EE82Pb208 is stable with 44 extra neutrons. This brings up the question of why a naturally occurring isotope of either EE84Po210 (42 extra neutrons) or EE84Po212 (44 extra neutrons) shouldn't be be more stable than the OE83Bi209.Has anybody examined old samples of EE84Po210 to see if there is any residual indicationa of a stable Po210 isotope. WFPM68.89.1.0 (talk) 12:13, 9 April 2008 (UTC)

I'm not sure I understand your question. Po-210 and Po-212 don't have isotopes, they are isotopes of polonium. Do you mean whether any of them might have nearly-stable nuclear isomers? I suppose that's possible in principle, but it would seem highly unlikely that they hadn't been discovered yet. In any case, I don't think you can infer anything about potential stability of polonium isotopes by simple comparisons to proton/neutron counts in isotopes of neighboring elements. Hqb (talk) 15:05, 9 April 2008 (UTC)

I am building real physical models of atomic nuclei and note that whereas EE nuclei can be built to appear dynamically balanced and thus appearing to be stable, the EOs and both OOs and OEs cannot. Thus EE82Pb208 appears stable as does 206 and 204. The additional proton of OE83Bi209 makes it appear unstable but is balanced by an additional proton to make EE84Po210. Since natures production process would undoubtedly pruduce some of everything I wonder if our 83Bi209 plus neutron flux process is capable of producing all the possible structures of EE84Po210 that is possible, and that some of these EE type possibilities might be stable.WFPM 65.65.224.94 (talk) 17:03, 9 April 2008 (UTC)

crystal structure

the text says 'cubic' but the picture is rhombohedral. compare with oxygen, bismuth. 99.231.208.23 (talk) 13:39, 1 May 2008 (UTC)