4 ms·

According to Wikipedia, Polonium is 5000 times more radioactive than Radium (just 0.001g of Po emits the same number of particles as 5g of Ra). It has a half l

by todd8 4y ago

According to Wikipedia, Polonium is 5000 times more radioactive than Radium (just 0.001g of Po emits the same number of particles as 5g of Ra). It has a half life of just 138 days so in only 4.6 years the missing Polonium will be equivalent in radioactivity to Radium, which is known to cause cancer. This doesn't sound like something that should be treated lightly.

cshimmin 4y ago
Sure but all that means is that 1g of radium will have the same activity as 0.2mg of polonium. Of course they will also have different decay spectra etc. We don't know how big the source was that the students lost, but I'm guessing that if they just gave up after a few days, it probably wasn't a very high activity. This means either very low mass, or a higher mass but just older so that it's decayed away.
- fnands 4y ago
  It was tiny, I think something like this: https://www.flinnsci.com/alpha-source-polonium-210/ap8794/ https://www.flinnsci.com/alpha-source-polonium-210/ap8794/ They were letting undergrads handle it, so definitely wasn't a large source. Also, hey Chase! Funny to see you in the wild (Ferdi here)
  - Aeolun 4y ago
    It’s nice that they add just enough material for a given amount of radioactivity.
el_benhameen 4y ago
I found a polonium-loaded anti-static brush for photography in a box from my parents’ attic. Scared the shit out of me at first. Called the hazardous waste folks and had a fun chat with a perplexed employee. We finally decided that, as it was from the 70’s, it had long since decayed into harmlessness and was fine to throw away.
- kibwen 4y ago
  How did you realize it once contained polonium?
  - el_benhameen 4y ago
    It had a big label on it that said “DANGER: POLONIUM. DO NOT INGEST”!
    - bogeholm 4y ago
      A reasonable basis for the polonium hypothesis
    - TedDoesntTalk 4y ago
      If only Alexander Litvinenko had such a warning…
- krasin 4y ago
  > polonium-loaded anti-static brush for photography At first, I was very surprised to hear it's a thing, but apparently it is and one can buy for just $170: https://amstat.com/products/anti-static-brush-with-ionizing-cartridge-1.html https://amstat.com/products/anti-static-brush-with-ionizing-...
- beeforpork 4y ago
  Applied Science youtube channel uses this and explains it a bit: https://www.youtube.com/watch?v=ZBHIp967TD8 https://www.youtube.com/watch?v=ZBHIp967TD8
- wkat4242 4y ago
  Uhhh be careful with that reasoning. Some radioactive isotopes don't decay into stable isotopes but into other radioactive, sometimes more dangerous ones. It can be a whole chain until it reaches a stable element. Not sure about this particular polonium isotope. But don't expect something to be harmless after 10x the half-life per se.
agoose77 4y ago
The important question is how much of a sample was lost. Ultimately, AIUI, the health risk depends upon the exposure in a ~ linear fashion. At least, in radiological protection that's used. The LNT model errs on the side of caution; assume that any exposure is harmful, linearly extrapolating from the high dosages seen in Hiroshima, etc, where we have data of the impact of exposure on the body. In reality, we expect a threshold effect as the body is able to repair some damage. The dose of radiation has different meanings; absorbed, equivalent, effective. These are just different calculations, starting from how much energy the body received (absorbed), to taking into account the different kinds of radiation whose effects differ (equivalent), to where in the body the dose as received (different organs at different risk, effective). The half-life of 210Po is 138 days, so it's ~10x less active than 223Ra. That's meaningless with respect to the health risk, though; the activity of the sample is ultimately selected by its intended use. Most samples are sized according to the dose requirements. At least, that's my understanding (physics, not medical). In general we don't want to over-size a source as there are greater regulations. Similarly, we don't want sources to become useless too quickly. In any case, this is definitely bad — 5000x less activity is not good if it's greater than the lethal dose. Because radioactive sources are so small, the risk is not likely to be distributed; you get the whole dose, or nothing.* * Unless it gets dispersed somehow. Dose: https://en.wikipedia.org/wiki/Equivalent_dose#/media/File:SI_Radiation_dose_units.png https://en.wikipedia.org/wiki/Equivalent_dose#/media/File:SI... LNT: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663584/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663584/
- fnands 4y ago
  Yes, it was a tiny source, and luckily emits alpha particles which are easy stop by even small amounts of material. > * Unless it gets dispersed somehow. Exactly, the real worry was that it would get crushed and would be breathed in, in which case it would be a real problem. But even so, the school had to file a report with the nuclear regulator iirc. Lot of paperwork.
  - timr 4y ago
    Well, if there was paperwork, then the risk was fully mitigated. Paper does block alpha particles. /s
tgsovlerkhgsel 4y ago
"Small" is likely meant relative to the material. So a "small" Polonium source and a "small" Radium source would typically refer to a Polonium source having orders of magnitude less material, but a similar radiation level.
timr 4y ago
It's an alpha emitter (and if being used in a university classroom, probably a sealed one). Unless you eat it, the danger is not comparable. Radium, in contrast, emits gamma radiation, which presents more of a threat to casual bystanders. All of which is to say: you can't just compare "radioactivity" levels and extrapolate to "danger".
- eternityforest 4y ago
  I'm more scared of alpha than gamma. If the alpha source gets tampered with and becomes a dust somehow, it could stay in someone's lungs, and kill someone without being easily detectable. Cheap eBay Geiger counters will probably tell you if gamma rays are an immediate danger, and if you're close enough to have problems, your probably also close enough to detect it.
  - LarryMullins 4y ago
    > I'm more scared of alpha than gamma. If the alpha source gets tampered with and becomes a dust somehow, it could stay in someone's lungs, and kill someone without being easily detectable. It's not an either/or sort of thing. Gamma decay occurs after alpha or beta decay, so a gamma source will also emit alpha or beta radiation. In the case of Cs-137, it emits a lot of beta radiation. Normally this is shielded, but normally it doesn't fall off a truck..

by todd8 4y ago

cshimmin 4y ago

Sure but all that means is that 1g of radium will have the same activity as 0.2mg of polonium. Of course they will also have different decay spectra etc. We don't know how big the source was that the students lost, but I'm guessing that if they just gave up after a few days, it probably wasn't a very high activity. This means either very low mass, or a higher mass but just older so that it's decayed away.

fnands 4y ago
It was tiny, I think something like this: https://www.flinnsci.com/alpha-source-polonium-210/ap8794/ https://www.flinnsci.com/alpha-source-polonium-210/ap8794/ They were letting undergrads handle it, so definitely wasn't a large source. Also, hey Chase! Funny to see you in the wild (Ferdi here)
- Aeolun 4y ago
  It’s nice that they add just enough material for a given amount of radioactivity.

el_benhameen 4y ago

I found a polonium-loaded anti-static brush for photography in a box from my parents’ attic. Scared the shit out of me at first. Called the hazardous waste folks and had a fun chat with a perplexed employee. We finally decided that, as it was from the 70’s, it had long since decayed into harmlessness and was fine to throw away.

kibwen 4y ago
How did you realize it once contained polonium?
- el_benhameen 4y ago
  It had a big label on it that said “DANGER: POLONIUM. DO NOT INGEST”!
  - bogeholm 4y ago
    A reasonable basis for the polonium hypothesis
  - TedDoesntTalk 4y ago
    If only Alexander Litvinenko had such a warning…
krasin 4y ago
> polonium-loaded anti-static brush for photography At first, I was very surprised to hear it's a thing, but apparently it is and one can buy for just $170: https://amstat.com/products/anti-static-brush-with-ionizing-cartridge-1.html https://amstat.com/products/anti-static-brush-with-ionizing-...
beeforpork 4y ago
Applied Science youtube channel uses this and explains it a bit: https://www.youtube.com/watch?v=ZBHIp967TD8 https://www.youtube.com/watch?v=ZBHIp967TD8
wkat4242 4y ago
Uhhh be careful with that reasoning. Some radioactive isotopes don't decay into stable isotopes but into other radioactive, sometimes more dangerous ones. It can be a whole chain until it reaches a stable element. Not sure about this particular polonium isotope. But don't expect something to be harmless after 10x the half-life per se.

agoose77 4y ago

The important question is how much of a sample was lost. Ultimately, AIUI, the health risk depends upon the exposure in a ~ linear fashion. At least, in radiological protection that's used. The LNT model errs on the side of caution; assume that any exposure is harmful, linearly extrapolating from the high dosages seen in Hiroshima, etc, where we have data of the impact of exposure on the body. In reality, we expect a threshold effect as the body is able to repair some damage. The dose of radiation has different meanings; absorbed, equivalent, effective. These are just different calculations, starting from how much energy the body received (absorbed), to taking into account the different kinds of radiation whose effects differ (equivalent), to where in the body the dose as received (different organs at different risk, effective). The half-life of 210Po is 138 days, so it's ~10x less active than 223Ra. That's meaningless with respect to the health risk, though; the activity of the sample is ultimately selected by its intended use. Most samples are sized according to the dose requirements. At least, that's my understanding (physics, not medical). In general we don't want to over-size a source as there are greater regulations. Similarly, we don't want sources to become useless too quickly. In any case, this is definitely bad — 5000x less activity is not good if it's greater than the lethal dose. Because radioactive sources are so small, the risk is not likely to be distributed; you get the whole dose, or nothing.* * Unless it gets dispersed somehow. Dose: https://en.wikipedia.org/wiki/Equivalent_dose#/media/File:SI_Radiation_dose_units.png https://en.wikipedia.org/wiki/Equivalent_dose#/media/File:SI... LNT: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663584/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663584/

fnands 4y ago
Yes, it was a tiny source, and luckily emits alpha particles which are easy stop by even small amounts of material. > * Unless it gets dispersed somehow. Exactly, the real worry was that it would get crushed and would be breathed in, in which case it would be a real problem. But even so, the school had to file a report with the nuclear regulator iirc. Lot of paperwork.
- timr 4y ago
  Well, if there was paperwork, then the risk was fully mitigated. Paper does block alpha particles. /s

tgsovlerkhgsel 4y ago

"Small" is likely meant relative to the material. So a "small" Polonium source and a "small" Radium source would typically refer to a Polonium source having orders of magnitude less material, but a similar radiation level.

timr 4y ago

It's an alpha emitter (and if being used in a university classroom, probably a sealed one). Unless you eat it, the danger is not comparable. Radium, in contrast, emits gamma radiation, which presents more of a threat to casual bystanders. All of which is to say: you can't just compare "radioactivity" levels and extrapolate to "danger".

eternityforest 4y ago
I'm more scared of alpha than gamma. If the alpha source gets tampered with and becomes a dust somehow, it could stay in someone's lungs, and kill someone without being easily detectable. Cheap eBay Geiger counters will probably tell you if gamma rays are an immediate danger, and if you're close enough to have problems, your probably also close enough to detect it.
- LarryMullins 4y ago
  > I'm more scared of alpha than gamma. If the alpha source gets tampered with and becomes a dust somehow, it could stay in someone's lungs, and kill someone without being easily detectable. It's not an either/or sort of thing. Gamma decay occurs after alpha or beta decay, so a gamma source will also emit alpha or beta radiation. In the case of Cs-137, it emits a lot of beta radiation. Normally this is shielded, but normally it doesn't fall off a truck..