Radon and Smoking (individual vs aggregate)

["Field, R. William" <bill-field@UIOWA.EDU>]

Dr. Cohen wrote, "If you don't understand that the BEIR

Reports use a liinear relationship between lung cancer and radiation

exposure, there is no point in discussing these matters with you. What do

you think the LNT debate is all about?"




Dr. Cohen,  


If you get a chance, could you respond this the last post. 



I agree, it makes little sense to continue when we are in disagreement

over basic facts about BEIR VI.  However, rather than conveying my

interpretation of BEIR VI, let me quote:   


 "Miner data clearly indicate that the relationship of

lung-cancer occurrence in a person, to cumulative exposure, is not simply

linear, and that the joint relationship of radon and smoking is not

additive" (Page 376 BEIR VI).   


Relative risks for cumulative radon exposure and lung cancer have

dependencies on other factors other then smoking and radon.  There

are vectors of covariates that affect background lung cancer rates and

other vectors that modify the exposure response relationship. 



Let's take just one example, if you hope to test the LNT theory using an

ecologic study, you must know the joint distribution of radon exposure

and smoking in EACH county (Guthrie's paper I faxed you goes into detail

on how to possibly get at this information).  Nonetheless, you state

by using "rigorous mathematics" in your 1995 paper you prove

you can test the LNT theory using an ecologic study.  You may have

used math, but you needed an assumption that all smokers have the same

smoking duration and intensity to obtain the Cohen derived formula. 

This faulty assumption invalidates your derived equation.  This

faulty assumption can not be later verified or treated by after the fact

stratifications using more averaged smoking data especially without

knowing the joint distribution of the covariates.  In fact, you have

even previously stated, your analysis only,  "crudely

introduces the pack-year concept."  Dr. Gilbert has already

provided evidence that your results are confounded by smoking, because

other smoking related cancers are also negatively associated with your

county radon data (Perhaps Jim has a mechanism that shows alpha

irradiation to the lung decreases the cancer rates in other organs - if

so please share it).  So when you say, the LNT fails, what you are

really proving is that the Cohen derived LNT formula that used faulty

assumptions failed.  While I am not a loyal LNT supporter, I find

myself in agreement with Dr. Piantadosi who said in 1994, your findings

do, "more to discredit the analysis than the theory."  I

would not expect you to be able to explain your inverse findings by using

your "treatments" as you call, since the Cohen derived formula

used to test the LNT suffers from faulty assumptions.


Regards, Bill Field





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