Re: EMF Cancer Risk

["Otto G. Raabe" <ograabe@ucdavis.edu>]

At 12:48 PM 12/06/1999 Bill Prestwich wrote:
>Is this an ecological study? On the surface it appears to be somewhat
>analogous to Dr.Cohen's radon studies in approach. I imply absolutely no
>ctiricism by asking this. On the contrary, I am just curious as to whether
>it will invoke the same response from the epidemiological community if it

December 7, 1999
Davis, CA

Concerning my December 6 posting:

The eight-year U.K. Childhood Cancer Study, published in The Lancet medical
journal, compared levels of electromagnetic fields (EMF) in the homes,
schools, and nurseries of 2,226 children with cancer and an equal number of
healthy children and found no EMF effect on the results.

This report describes a case-control study, not an ecological study. In a
case-control study the actual exposure or dose for each person in the study
is evaluated for each case and each control subject. So, there is an
estimate of personal dose for each person in the study reflecting that
person's history. 

In an ecological study, such as Cohen's radon studies, there is no
information about the specific exposure or dose for any person in the
study. Only estimates of average overall group exposures or doses are
available. The actual dose to any person is unknown. Assuming that the
average dose to a group of persons is equal to the actual dose to specific
affected members of the group and relating it their risk is called the
ecological fallacy. [It is interesting to note that the EPA has based new
standards for airborne particulate matter in the environment on ecological
studies that are seriously flawed by the ecological fallacy.]

Cohen has correctly pointed out the ecological fallacy is negated if the
linear no-threshold theory is correct for radiation risk since in that
situation the observed risk to a group of people would not depend on how
the dose was distributed among the group members. Hence, Cohen's studies
are a valid test of the LNT theory and cannot be discounted by the
ecological fallacy.

Otto


		*****************************************************
		Prof. Otto G. Raabe, Ph.D., CHP
              Institute of Toxicology & Environmental Health (ITEH)
		   (Street address: Building 3792, Old Davis Road)
		University of California, Davis, CA 95616
		Phone: 530-752-7754  FAX: 530-758-6140
		E-mail ograabe@ucdavis.edu
              *****************************************************
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