Re: Cohen's Observation

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

On Mon, 16 Jun 2003 epirad@mchsi.com wrote:



> Dr. Cohen,

>

> I wrote: You stated in a previous paper that 27% of bedrooms in your

>          data set were located in the basements.

>

> Cohen wrote: I am quite sure this is not correct. If you insist, I will try

>              to find my papers on this.

>

> If we can not agree on what you write in your own papers, we surely can not

> agree on more scientific issues.



	--I had trouble finding my paper on this when I wrote the above. I

have now found it, and it states that 27% of the bedrooms measured were

"mostly below ground". My apologies for not remembering that detail in my

work done 13 years ago.

      These rooms were specified as "bedroom" rather than

"basement" which was another option. This was part of an extensive

discussion on problems with interpreting our measurements, and was taken

into account in arriving at our final results. Even so, I did not have

great confidence in our measurements until I studied their correlation

with other data dets on radon levels in homes.



> I previously accepted your offer to allow a

> mutually agreed upon scientists to review my stated reason why you are finding

> an inverse association, but you did not agree to any of the highly regarded

> scientists I suggested



	--I accepted the only theoretical physicist you suggested but did

not get a response from him. I will agree on any other theoretical

physicist you suggest.

>

> The reason I enter this debate is not about ego, but rather because so many

> people including knowledgeable HPs and Physicists misinterpret your findings

> to indicate prolonged residential radon exposure does not cause lung cancer

> (eventhough the vast majority of case-control studies indicate it does). You

> have stated yourself ecologic studies can not assess risk.  This needs to be

> stated by you more often.



	--It is stated clearly and prominently in several of my papers,

including my original 1995 paper and item #7 on my web site which I have

been recoomending so often lately. My study is designed to test LNT. If

LNT is valid, some explanation must be found for the huge discrepancy

between its predictions and my data. If such an explanation cannot be

found, my only conclusion is that LNT is not valid. I can't imagine how

anyone can read my papers and miss that point.

	My personal opinion is that the people you refer to do not read my

papers; they see my plot showing decreasing lung cancer rates with

increasing radon levels and pay attention to nothing else. Actually, that

plot was the beginning of my studies, and since I came to believe it, I

have spent 10 years trying to explain how it might be so discrepant with

LNT. That work is summarized in item #7 on my web site.



 While ecologic studies can not assess causality,

> analytic epidemiology studies (such as case-control studies) do have the

> ability to establish causality.



>  This debate has not been about the

> validity of the LNT, this debate has been about the limitations of ecologic

> studies. You state the limitations inherent in ecologic studies do not exist

> if you use an ecologic design to test the LNT, no knowledgeable epidemiologist

> would agree with such a contention.



	--I did not say they do not exist; that is why I have spent 10

years to investigate them in an effort to see if they can explain my

discrepancy with LNT predictions. My statement that you distort here is

that the basic problem with an ecological attempt to determine a

dose-response relationship, that the average dose does not determine the

average risk, is avoided if the relationship is LNT. That is why my study

can test LNT, but if LNT is not valid, it cannot determine the

dose-response relationship. That does not mean that confounding factors

can be ignored; that is why I have spent 10 years trying to find ways they

can explain away the problem.



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