Re: Dumb questions and comments on ecological/case studies

[BERNARD L COHEN <blc+@PITT.EDU>]

On Thu, 6 Jun 2002 epirad@mchsi.com wrote:



> Cohen stated,

> --According to LNT, something like 10% of lung cancers

> are due to

> > > radon; moreover, variations in radon levels among

> U.S. counties are very

> > > much larger than variations in smoking prevalence;

> moreover, radon levels

> > > are determined by geology and house construction,

> and neither of these is

> > > obviously related to smoking, so correlations

> between radon and

> > > smoking cannot be very large. In fact, correlations

> between radon and any socioeconomic variables are not

> large.

>

> When we regressed Cohen’s adjusted smoking percentages

> for males and females on Cohen's radon levels.  In both

> instances there was a significant (p < 0.00001) negative

> association between smoking and radon.  The slopes were

> 2.698 for males and 1.981 for females.  Apparently,

> there are more smokers in counties with low radon

> levels.



	--This has been mentioned in my papers many times. If it were not

for this correlation, the discrepancy with LNT would be even larger. But

still this correlation is not nearly large enough to make an important

difference. That is what I meant when I said that this correlation could

not be "very large".



  Since smoking is by far the leading cause of

> lung cancer, mortality rates will be elevated in

> counties with lower radon levels.  In order to get a

> clear picture of the association between radon and lung

> cancer, it is essential that smoking be adequately

> controlled.  However, this will not be possible due to

> the crude classification of exposure (smoker/nonsmoker)

> used by Cohen.



	--This classification is the one used by BEIR-IV which is the

theory I was testing. But I have gone beyond that in papers considering

the possibility that radon levels differ for smokers and non-smokers, and

intensity of smoking varies from county to county.





> The correlation between radon and lung cancer does not

> have to be large to cause the effect seen by Cohen (in

> part because of the large risk posed by smoking)since

> many other adverse health factors are correlated with

> smoking including socioeconomics, healthcare, etc.  All

> of these factors add to more lung mortality in lower

> radon counties.





	--All of these matters have been treated in my papers. Incidently

I have shown that even a perfect correlation between smoking frequency and

radon levels does not explain my discrepancy with LNT



> Cohen's poor accounting for the cumulative effect of

> these factors causes his inverse findings.  This

> assertion is supported by the fact that his inverse

> correlation is found for other smoking related cancers

> that should not be associated with radon.



	--The issue of other smoking related cancers was first introduced

to me only a few days ago on this listserv and I haven't had time to look

into it. Could you specify which cancers are "smoking related"? In one

message you included prostate cancer -- how is that smoking related?





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