[ RadSafe ] Fwd: Polonium-210
Cindy Bloom
radbloom at comcast.net
Tue Nov 28 10:56:02 CST 2006
John,
I agree. I was just letting my imagination explore possibilities that
hadn't been mentioned.
Cindy
At 07:56 AM 11/28/2006 -0800, John R Johnson wrote:
>Cindy
>
>I have never seen any chemical toxicity data either, probable because it
>doesn't have a stable isotope.
>
>FYI, the easiest way to get Po-210 is from Pb-210. I've copied and pasted
>information frm my earlier message to Radsafe
>"The progeny of Ra-226 is Rn-222, Po-218, Pb-214, Bi-214, Po-214, Pb-210,
>Bi-210, Po-210 and Pb-206 (stable). The longest lived one is Pb-210 (~21
>years) and it could be a/the source for Po-210 (half life ~ 138 days)"
>
>Collecting Po-210 from Pb-210 in NORM would be easier than from Rn-222.
>
>John
> _________________
>John R Johnson, Ph.D.
>*****
>President, IDIAS, Inc
>4535 West 9-Th Ave
>Vancouver B. C.
>V6R 2E2
>(604) 222-9840
>idias at interchange.ubc.ca
>*****
>
>
>
>
>-----Original Message-----
>From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl]On
>Behalf Of Cindy Bloom
>Sent: November 28, 2006 7:31 AM
>To: radsafe at radlab.nl
>Subject: [ RadSafe ] Fwd: Polonium-210
>
>
>
> >I should first say that I am a health physicist and an internal
> >dosimetrist, but my knowledge of biology and toxicology is related
> >primarily to internal dosimetry (and family and friend's medical
> >crises). I do have a fair amount of experience in operational health
> >physics and estimating internal doses and find that the alleged polonium
> >poisoning case engages my curiousity.
> >
> >The following are some thoughts and questions about polonium. I don't
> >seem to be able to find any specific information regarding the ingestion
> >toxicity of polonium, but it seems like a number of "poisons" require
> >acute ingestion doses on the order of milligram quantities to produce
> >their short-term toxic chemical (versus radiological) effects. That would
> >be a whole lot of radioactive polonium: a milligram of Po-210 would be
> >almost 4.5 curies.
> >
> >Polonium-210 (138.38-day half-life) is available in a variety of forms,
> >and as some have pointed out is readily available in static eliminator
> >brushes (I've typically seen quantities of 150 microcuries to 10
> >millicuries, but I'm sure they are available in larger activities), and I
> >suppose it might be easy enough for an experienced chemist to recover this
> >metal and create a chemical form that was readily transportable and easy
> >enough to add to food. (It would also be possible to collect polonium
> >from the radon in the air, although perhaps not very practical if the
> >radon levels were not elevated. If you had a facility that had an average
> >Rn concentration of 4 picocuries/liter, and an equilibrium factor of 0.4,
> >about 1.25 billion liters of air would be needed to collect a millicurie
> >of Po-210 (assuming 100% collection efficiency). A concentrated source of
> >radium might allow for more practical collection, and some have noted
> >there are other means of creating/collecting/obtaining Po-210, but these
> >methods might require special access to equipment/materials.
> >
> >Using ICRP 60+ models, the dose from a 1 millicurie Po-210 ingestion
> >intake on November 1 (this would be an intake of about 0.22 micrograms of
> >Po, if I've done my math correctly) would result in the organ doses
> >equivalent and doses as of November 8, 16 (day of hospitalization?) and 23
> >(day of death) shown at the end of this note. As Jim Barnes pointed out,
> >it probably doesn't make sense to look at dose equivalent, rather the dose
> >in rad should be considered to determine deterministic effects, so the
> >organ doses were calculated by dividing the doses equivalent by the alpha
> >weighting factor of 20.
> >
> >Based on the above, it seems like the ingested dose would have had to be
> >at least in the range of 3 to 10 millicuries to result in the effects
> >reported. This is still in the range of micrograms of Po-210 intake.
> >
> >I also wonder what Po tastes like. Would polonium chloride taste like a
> >salt? Would Po be easy to add to food or drink. It seems like the dose
> >added to the food might need to be much larger to ensure that the intake
> >was sufficiently large.
> >
> >Po-210 is primarily an alpha emitter, but 1e-5 of the time it emits a 0.8
> >MeV photon. Using the old 6CEn equation indicates that for a millicurie,
> >the photon exposure rate at a foot would be 0.048 microentgen per
> >hour. This doesn't seem like much but the 0.8 MeV photon emission rate
> >would be 22,200 per minute, and that seems like a detectable quantity (if
> >someone were really looking). (A curie (223 milligrams) of Po-210 would
> >produce an exposure rate of about 48 microroentgen per hour, which is
> >about 4 times a typical background level.)
> >
> >ICRP 23 notes that we all have Po-210 in us, primarily from foods, but
> >cigarettes are a significant source for some. Blood levels reportedly
> >range from 1 to 54 pCi/kg (reference man has a blood volume of 5200 ml,
> >and assuming a density of 1 g/ml, reference man's blood would contain 5.2
> >to 280 pCi of Po-210). At 149 days, dogs exposed to Po-210 aerosols had
> >about half the retained Po-210 in their hair follicles (I can't tell if
> >this was 149 days after exposure or after 149 days of chronic exposure -
> >I'm guessing the former). Also ICRP 23 notes that trace amounts of Po-210
> >are normally found in hair and sweat.
> >
> >(Just an aside pico = 1E-12, micro = 1E-6, milli = 1E-3)
> >
> >Below are calculated doses per millicurie ingested (assumed to occur on
> >November 1). Sorry for not using SI units, but so many values were
> >readily available in curie-based units. Also, I seem to be unable to
> >align the columns in my table. They look alligned here, but they shift
> >when I send.
> >
> >Ingestion equivalent dose per millicurie
> >equivalent dose (rem) 11/8/2006 11/16/2006 11/23/2006
>50-y
> >Kidneys 1.08E+03 2.25E+03 3.14E+03 9.43E+03
> >Spleen 9.33E+02 1.94E+03 2.70E+03 8.12E+03
> >Liver 5.61E+02 1.17E+03 1.62E+03
> >4.87E+03
> >Red Bone Marrow 2.26E+02 4.68E+02 6.51E+02 1.95E+03
> >Lower Large
> >Intestine 2.06E+02 2.32E+02 2.53E+02 3.95E+02
> >Bone
> >Surface 1.38E+02 2.83E+02 3.94E+02 1.18E+03
> >Upper Large
> >Intestine 8.78E+01 1.14E+02 1.33E+02 2.71E+02
> >Small Intestine 3.63E+01 6.16E+01 8.08E+01 2.16E+02
> >Stomach 3.07E+01 5.59E+01 7.51E+01 2.11E+02
> >All other
> >organs 2.62E+01 5.14E+01 7.06E+01 2.06E+02
> >
> >Ingestion dose per millicurie for the period defined by an acute intake on
> >11/1/2006 and a period ending on the dates listed below.
> >dose (rad) 11/8/2006 11/16/2006 11/23/2006
>50-y
> >Kidneys 5.42E+01 1.13E+02 1.57E+02 4.72E+02
> >Spleen 4.66E+01 9.70E+01 1.35E+02 4.06E+02
> >Liver 2.80E+01 5.83E+01 8.12E+01
> >2.44E+02
> >Red Bone Marrow 1.13E+01 2.34E+01 3.26E+01 9.75E+01
> >Lower Large
> >Intestine 1.03E+01 1.16E+01 1.26E+01 1.98E+01
> >Bone
> >Surface 6.88E+00 1.42E+01 1.97E+01 5.90E+01
> >Upper Large
> >Intestine 4.39E+00 5.68E+00 6.65E+00 1.36E+01
> >Small Intestine 1.82E+00 3.08E+00 4.04E+00 1.08E+01
> >Stomach 1.54E+00 2.80E+00 3.76E+00 1.06E+01
> >All other
> >organs 1.31E+00 2.57E+00 3.53E+00 1.03E+01
>
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