Polonium Lethal Dose
Posted on November 29, 2006
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I thought this calculation of the lethal dose of Polonium could be interesting (I did not find it anywhere, but maybe it’s just me). Today the BBC published a nice article, but does not explain how a lethal dose can be computed.
The Lifetime Cancer Mortality Risk factor[1] for 1pCi (10^-12 curie[2] one milion of milion of curie) of Po 210 is 1.6 10^-9 (see http://www.ead.anl.gov/pub/doc/polonium.pdf)
That means giving 1pCi of Po210 someone has 1.6 10^-9 probability to die for cancer in a lifetime (80y).
To kill someone in one week I have to give him 80*52/(1.6 10^-9) pCi = 2.6 10^12 pCi = 2.6 Ci
One gram of Po has a radioactivity of 4500 Ci, then about 6 mg are lethal (a cube mm).
[1] It gives the probability to get a mortal cancer during the lifetime. In this case it means that absorbing 1 pico courie of radioactivity from Polonium one person out of 600,000,000 (that is 1/(1.6*10^9)) will get cancer.
[2] One curie is the activity of one gram of radium. By definition, now, one curie is 37 billion (3.7 x 10^10) disintegrations per second. That means that a gram of polonium emits 37 bilion alpha particles (2 protons and 2 neutrons all together) per second. A pico curie means 10^-12 or 0.000000000001 curie.
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