Re: Testimony of Steve Wing to US House of Representatives

["ruth_weiner" <ruth_weiner@email.msn.com>]

Pam:  Not quite.  Let me try an explanation.   At the present time, the
conversion factor from dose to potential latent cancer fatality is 0.0005
per person-rem of exposure.  This is based on observations which are
extrapolated linearly; that is (being exceedingly simplistic), in the region
where an observation could be made, 5 potentially fatal cases of cancer are
observed in 10,000 person-rem of exposure (for some numbers for this
derivation, see for example BEIR V).  10,000 person-rem can be interpreted
as 10,000 people each exposed to an average of 1 rem, or 20,000 exposed to
0.5 rem, etc.  Taking the first case, 10,000 people exposed to 1 rem each,
suppose the dose measurement was low and the 10,000 were actually exposed to
1.25 rem each, on the average.  Then the corrected risk factor would be
5E-4/1.25 rem, or 5 potentially fatal cancers per 12,500 person rem, or
4E-4/rem.  So the risk of a potentially fatal cancer will be reduced by
about 20% -- a person is actually less likely to get cancer than was
predicted by the original dose estimate.

If the individual has radiation-induced cancer -- the adverse effect has
actually occurred -- the risk estimate is completely irrelevant.  The
individual has cancer, and it is from whatever dose he or she received,
which is actual data, not an estimate of probability.  The risk estimate
only tells an individual who does not have cancer the likelihood or
probability that he or she will develop it on exposure to a particular dose.

Ruth Weiner
ruth_weiner@msn.com
-----Original Message-----
From: Pambo1@aol.com <Pambo1@aol.com>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Date: Friday, July 28, 2000 9:03 AM
Subject: Re: Testimony of Steve Wing to US House of Representatives


>I think I understand:
>
>If someone is studying me and I have actually gotten a much higher dose of
radiation than the researcher knows, then I am more likely to have adverse
effects but these adverse effects will be attributed to the lower dose the
researcher erroneously believes I got.  Thus, the statistics would
overestimate the risk of the lower dose, correct?
>
>Pam Gillis Watson
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