Talk:Polonium
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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).
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[edit] 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.
[edit] Talk
[edit] Archives
/Archive 1: mostly Nov 2006, regarding polonium poisoning and toxicity.
[edit] 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)
[edit] 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)
[edit] 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)
[edit] 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)
- 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)
[edit] 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)
[edit] 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[1] of the estimated 15,000-22,000 lung cancer deaths in the US every year that have been attributed to indoor radon.[2] 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)
[edit] 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)
