[ RadSafe ] lethal amount of Po-210

[Toro Laszlo]

Dear Collegues,

In the absence of quantitative information related to
the amount of Po-210, I made some calculations started
from ther information:
"How do we know it is Polonium-210?
Analysis of samples taken from the deceased person
identified Polonium-210 through its characteristic but
weak emission of gamma rays. This and further tests
are consistent with the deceased person having had a
large intake of Polonium-210. "
(http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=2086)
Assuming:
- they used a 30-40% relative efficiency well type
HPGe based gamma spectrometer
- a minimal value of a peak area (at 803keV) to be
considered by a skilled gamma spectrometrist "as peak"
about 2-3 E-3 ips (about 400-500 impulses in the whole
peak in 2E5 seconds)
-the measured sample is an urine sample taken after
7days from the ingestion (some source give 8 of
November the admitance in the hospital)
Results:
- the minimal activity measured in the sample is about
4000Bq
-the total ingested activity at 1 of November is
between 4-21MBq (0.1-0.6mCi; some tens-hundred ngram) 
-the dose (according ICRP 67 dose factors) is 5-25 Sv
If somebody is interested in the whole calculations
and assumtions I can send it privatelly (it was a good
exercice for dose reconstruction).
Regarding the "mass tests" for Po-210, I found some
old results in our files:
Po-210 in urine 
1983(samples from 70 subjects, children between
10-15y, from three rural communities) 304 mBq/l
(extreme values 222-518 mBq/l)
1983(samples from 77 subjects, children between
10-15y, from other three rural communities but
fundamentally different habits) 1.88 Bq/l (extreme
values 148-2930 mBq/l)
1988 (collective sample from 20 subjects, children
between 10-15y, from a school from Timisoara) 82mBq/l
with no significant difference femal/male.
It seems everybody of us should be found "positive"
against a Po-210 test.
 Sorry for this long message.

Laszlo Toro

======================================================================
Laszlo Toro PhD
senior scientist

Institute of Public Health Timisoara
Radiation Hygiene Dept.

RO 300226 Timisoara
Bd. V. Babes 16-18
Romania
ph. +40 256 492101 ext 34
fax +40 256 492101
e-mail toro at ispt.ro
       torolaszlo at yahoo.com
======================================================================

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