[ RadSafe ] Ecological Dose-Response Studies

[jjcohen at prodigy.net]

Otto,
    You have given a fascinating comparison of some EPA policies.
Can anyone explain how EPA determines when their rulemaking
can be based on ecological studies and when it cannot be.
Jerry Cohen



----- Original Message ----- 
From: "Otto Raabe" <ograabe at ucdavis.edu>
To: "RADSAFE" <radsafe at radlab.nl>
Sent: Thursday, February 08, 2007 9:48 AM
Subject: [ RadSafe ] Ecological Dose-Response Studies


> 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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