[ RadSafe ] BEIR VII

[Michael, Joey L]

Just curious.  What is the official number for background?  It seems to
me that there has to be a threshold (the threshold is the value of
background).  Realisticly I know it is a range and depends on your
location etc.  So within the range of background for various locations,
it seems that LNT would have to fall apart.

Here is my example.  A group of 10,000 people live in Town X with a
background of 3.6 mSv/yr.  They live ther for 1/2 yr.  They all move to
Town Y which has bkg = 7.2 mSv/yr.  They are exposed to an average bkg =
5.4 mSv for the  year.  Now, since 5.4 mSv is > 3.6 mSv/yr of Town X
(1.8 mSv difference), is there an additional risk of cancer (1 in 5556)
or is the risk = 0 because they were exposed to <bkg for Town Y.  

It seems like the risk changes by moving to a different town, and is not
consistant with the amount of exposure. 

Thanks for indulging me,

Joey Michael
Health Physicist Assistant
University of Iowa
Health Protection Office
335-8501