RE: Field's comments on Cohen's Observation

[epirad@mchsi.com]

Dukelow stated that from LNT, it follows as the night the day that 

radiologically-induced cancer incidence (and cancer mortality, given 

reasonably uniform standards of treatment) is a linear function of person-rem 

exposure.  As such,an ecologic study is adequate to test the LNT, assuming 

dependence and confounding issues can be handled.



I have two brief comments,



First, radiologically induced lung cancer is not a linear function as per 

person-rem unless you can describe the population in pretty good detail. For 

example, there are many factors that modify the assumed linearity such as age, 

smoking, etc. 



 Secondly, you state that ASSUMING dependence and confounding issues can be 

handled, an ecologic study is adequate to test the LNT"



That is really the heart of the problem isn't it?  Dr. Cohen has not persuaded 

me or from what I can tell most informed epidemiologist and statisticians that 

he has indeed handled effect modifiers and confounders adequately.  Dr. Cohen 

has not addressed the within county joint distributions of even smoking and 

radon let alone all the other socioeconomic factors that are also co-

correlated with smoking. Because Dr. Cohen uses ecologic smoking information, 

he can not hope to correct for the problem I mentioned above regardless how 

many attempts he makes.  



I previously sent Dr. Cohen a possible methodology to address the within 

county joint distribution problems, but he indicated to me that he thought the 

methodology had little to do with his work.  Therefore, that created a real 

impasse between us and is why I asked his cooperation in selecting a 3rd party 

to weigh in on this issue (especially if he plans to find any potential NCRP 

opinion on this topic biased).  We are getting no where in these discussions 

on the list and in fact the discussions have obviously become irritating to 

some (for which I apologize in part).



Regards, Bill Field



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