Re: Dose-response threshold from A-bomb survivor data

["John Moulder" <jmoulder@post.its.mcw.edu>]

> Roger Clark, in a talk at Harvard, stated that the A-bomb 
> survivor data shows that, if there is a threshold for radiation 
> induced cancer, it is below 5 rem. He quoted a paper by Pierce et al 
> in Radiation Research (1996). In case others are also deceived by 
> that paper, I am sending the following Letter-to-the-Editor. 

If this is what Clark said, then I think he is misquoting Pierce.  This is not 
even a major point of the Pierce paper.  The real point of the paper is an 
update on the data and examination of temporal trends, age-at-exposure and 
sex.  

The relevant material is on page 10

"We have considered the question of determining the minimum dose, d(m) for 
which there is a statistically-significant dose response when analysis is 
restricted to the range [0,d(m)]...  this d(m) is 0.05 Sv (P=0.02, two sided-
test)"

Quite apart from Cohen's issue with the statistical significance of the 
finding, this really does not address the question of "if there is a threshold 
how large could it be", since the analysis assumes a linear no-threshold dose-
response.

Also note that the statistical significance of Pierce's calculation has 
already been questioned in a exchange of letters in the Oct 1997 issue. 
(148:399-410)


John Moulder, Ph.D. (jmoulder@its.mcw.edu)
Associate Editor
Radiation Research

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