Risks of low level radiation - New Scientist Article

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

Cohen wrote;



--Note that my results are the same if we consider only one

section of the country, or if we select counties on any other basis.

-----------------



Dr. Cohen,



I have been following this thread for many years.  I saw in a post 

last year that Iowa has a SEER lung cancer database, the finest 

population breakdown by counties in the U.S., and the highest radon 

levels in the nation, why not limit your test to this one state as an 

example.  It has 100 counties and only 1 percent of the U.S. 

population.  Surely, if your findings are valid, they should be valid 

in Iowa?



The following paper is also of interest in this regard.



 Author(s): Brian J. Smith, R. William Field, and Charles F. Lynch 



 

Title:



 Residential 222Rn Exposure and Lung Cancer: Testing the Linear No-

Threshold Theory with Ecologic Data 



 

Category: Forum Article



 

Location: Health Physics, 75(1):11-17; 1998



 

Keywords: 222-Rn; epidemiology; cancer; lungs, human 



 

Abstract: In most rigorous epidemiologic studies, such as casecontrol 

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.  









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