Correction:

The half life of Polonium 210 is 138.4 days. Damn dyslexia!

That means there were 21 half decays and not 18 from then until now like I first calculated.

2 ^ 21 = 2,097,152 which is what you would have to divide by to get how much would be left.

The lethal and clandestine kill dosage is a few micrograms - and even if you have the patient right there, it is hard to detect with a few mics to work with.

1/2,000,000 of a microgram is getting down to countable numbers of atoms.

I call utter BS on this report.