Re: Re: Source of cancer data

["John Williams" <JohnWi@law.com>]

Jim,



I am not talking about the Iowa Radon Study, which most 

epidemiologist believe is the state-of-the-art Radon Study. It is 

even highlighted on the EPA web site:  http://www.epa.gov/iaq/radon/ 

Rather, I am talking about Smith using Cohen's own data and just 

inserting more valid lung cancer incidence information then the 

mortality data he used.  Read the paper by Smith et al. instead of 

just the abstract.



Health Phys 1999 Sep;77(3):328-9 Related Articles, Books, LinkOut  





Comment on: 

Health Phys. 1999 Apr;76(4):439-40 



Cohen's paradox.



Health Phys 1998 Jul;75(1):11-7 Related Articles, Books, LinkOut  





Comment in: 

Health Phys. 1998 Jul;75(1):23-8; discussion 31-3 

Health Phys. 1999 Mar;76(3):316-9 



Comment on: 

Health Phys. 1995 Feb;68(2):157-74 

Health Phys. 1997 Apr;72(4):623-8 



Residential 222Rn exposure and lung cancer: testing the linear no-

threshold theory with ecologic data.



Smith BJ, Field RW, Lynch CF.



College of Medicine, Department of Preventive Medicine and 

Environmental Health, University of Iowa, Iowa City 52242, USA.

bill-field@uiowa.edu



In most rigorous epidemiologic studies, such as case-control and 

cohort studies, the basic unit of analysis is the individual. Each 

individual is classified in terms of exposure and disease status. 

However, in ecologic epidemiologic studies, the unit of analysis is 

some aggregate group of individuals. Summary measures of exposure and 

disease frequency are obtained for each aggregate, and the analyses 

focus on determining whether or not the aggregates with high levels 

of exposure also display high disease rates. The ecologic study 

design has major limitations, including ecologic confounding and 

cross level bias. Cohen has attempted to circumvent these limitations 

by invoking the linear no-threshold theory of radiation 

carcinogenesis to derive aggregate "exposures" from individual-level 

associations. He asserts that, "while an ecologic study cannot 

determine whether radon causes lung cancer, it can test the validity 

of a linear-no threshold relationship between them." Cohen compares 

his testing of the linear no-threshold relationship between radon 

exposure and lung cancer to the practice of estimating the number of 

deaths from the person-rem collective dose, dividing the person-rem 

by the number of individuals in the population to derive the 

individual average dose, and then determining individual average risk 

by dividing the number of deaths by the number of individuals in the 

population. We show that Cohen's erroneous assumptions concerning 

occupancy rates and smoking effects result in the use of the wrong 

model to test the linear no-threshold theory. Because of these 

assumptions, the ecologic confounding and cross level bias associated 

with Cohen's model invalidate his findings.



>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

 Furthermore, when more recent Iowa county lung cancer incidence 

rates are regressed on Cohen's mean radon levels, the reported large 

negative associations between radon exposure and lung cancer are no 

longer obtained.



..................................

Cohen does not even attempt to provide discrete analytical proof that 

they are wrong.



John Williams



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