Re: Risks of low level radiation - New Scientist Article

[BERNARD L COHEN <blc+@PITT.EDU>]

On Fri, 14 Dec 2001, John Williams wrote:



> 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?



	My study does include Iowa and every other state individually, as

well as combinations by region, and compilation for the whole country.

Results for all of these are in my papers. The problem with a single state

is that there are far fewer data points so the statistics are far less

convincing. For example, in my latest data for Iowa, the slope of the lung

cancer vs radon regression differs from zero by 1.1 standard deviation

(SD) for males and by 0.3 SD for females. Thus, the results are hardly

convincing. By comparison, the results are much more convincing for

the entire U.S.; the difference is 15 SD for males and 12 SD for females.

	There is also much more chance for confounding factors to be

important in an individual state, whereas in the nation as a whole, these

tend to average out. For example, an ethnic group that is more susceptible

to lung cancer may live in a high radon area in a single state.



> The following paper is also of interest in this regard.

>

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



	--Why do you disregard my published response to that paper?



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