[ RadSafe ] Ecological Dose-Response Studies

[Bernard L. Cohen]

My papers clearly and prominently state that ecological studies cannot 
*determine* a dose-response relationship, but they have a much better 
chance of *testing* a linear-no threshold relationship. The problem is 
complicated by possible confounding factors, but I have examined over 
500 potential confounding factors and none of them were found to affect 
my results. No one has yet suggested a possible confounding factor that 
I have not clearly shown to have no effect on my results. I could easily 
suggest possible confounding factors that would invalidate any 
epidemiological study.

Otto Raabe wrote:

> February 8, 2007
>
> The EPA in association with BEIR VI has rejected the detailed 
> ecological studies of Bernard Cohen that showed people living in 
> regions with higher radon levels in air in homes tended to have lower 
> lung cancer rates and demonstrating that the LNT model does not apply.
>
> In ecological studies the concentration of a potential toxicant is 
> measured in general areas where people are being exposed, but no 
> information is available about the actual dose to or exposure of any 
> particular person. Comparisons are made of rates of disease in people 
> who live in areas with different pollutant levels.  Because the actual 
> level of exposure of the people with disease is not really known, 
> statisticians tend to give little weight to the results of ecological 
> studies. Also, unknown confounders can badly skew the results.
>
> Ironically, EPA has a different view for air pollutants, For about ten 
> years ecological studies of air pollutants, especially particulate 
> matter, have been used to show an association between concentrations 
> in outdoor air and diseases in people. Often the affected people are 
> in hospitals breathing clean air and the measurements of pollutants 
> are made outdoors many miles away. In today's news a study from the 
> University of Washington involving 65,893 women who were presumably 
> exposed to some extent or other to normal outdoor levels of airborne 
> particulate matter concluded that women living in areas with higher 
> concentrations had higher levels of heart disease. It isn't clear what 
> exposure anyone received since the measurements were presumable made 
> of outdoor levels at centrally located air monitoring stations and no 
> one knows where the women with heart disease were during all of their 
> lives or what they actually inhaled.  On the basis of these and other 
> similar studies the EPA in 2011 is scheduled to question its standards 
> for airborne particulate matter. Presumably they will recommend lower 
> ambient air concentration limits on particulate matter and limits on 
> emission sources.
>
> Otto
>
>
> **********************************************
> Prof. Otto G. Raabe, Ph.D., CHP
> Center for Health & the Environment
> University of California
> One Shields Avenue
> Davis, CA 95616
> E-Mail: ograabe at ucdavis.edu
> Phone: (530) 752-7754   FAX: (530) 758-6140
> ***********************************************  
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