Re: LNT models -Constancy of Radon levels over time??

[Bernard L Cohen <blc+@pitt.edu>]

On Wed, 8 Mar 2000 RadiumProj@cs.com wrote:
> 
> This is likely to be a poor assumption over the lifetime of a large fraction 
> of today's residents for the following reason. Over the past many decades 
> there has been an effort to reduce energy consumption in existing homes by a 
> combination of measures [insulation, storm windows, weatherstripping, 
> caulking] all of which will reduce air infiltration and increase indoor radon 
> levels, on average. Accordingly, the radon levels measured today in the 
> "average home" may not reflect the time-averaged radon levels to occupants of 
> an older home which might determine a long-term residents' actual 
> radon/lung-cancer dose-response relationship. Also many people who grew up in 
> older, draftier homes with  likely lower radon levels will have moved into 
> homes of newer construction with much higher radon levels due to their being 
> built much tighter.
> 
> To the extent that radon levels in the indoor environment are likely to have 
> increased with time, both due to the upgrading of older homes and in the fact 
> that newer construction is much, much less subject to air infiltration [and 
> dilution of indoor radon], resulting in higher radon levels, radon levels 
> over time are very unlikely to have been constant with time even thought 
> radium levels in local soil are constant. 
> 
> If the historical long-term  time-averaged radon levels to residents were 
> much  lower to people than assumed based on recent measurements in today's 
> homes, this would seem to be a flaw or serious confounding variable not 
> addressed to my knowledge, in Dr. Cohen's argument regarding the lack of 
> correlation between elevated radon levels and lung cancer rates.

	--My paper in HEALTH PHYSICS 60:631-642 presents elaborate
studies of radon levels vs age of houses, and the differences are not
large. It also includes a study of houses whose answer to the question
"How much has been done since 1975 to reduce heat loss from your house by
weatherstripping, closing gaps under doors, sealing windows, etc" were
"Much", "little", or "nothing". The relative radon levels corresponding to
these answers were:	much - 1.02; little - 0.92; nothing - 1.00. (Note
that 1975 was when the drive to reduce enrgy consumption began, following
the Energy crisis").
	These studies involved tens of thousands of houses from every
section of the nation, and results were similar for all sections.
	I might point out that these problems are much more likely to
cause trouble in case-control studies. It is much more likely that there
was a change in a particular house than in the county average.
	I might also point out that, for these problems to affect my test
of LNT, they would have to be different for different counties in a way
that correlates very strongly with radon levels. I have studied over 500  
factors that might potentially confound the lung cancer vs radon
relationship, and none of them correlates strongly enough with radon
levels to make a difference.

Bernard L. Cohen
Physics Dept.
University of Pittsburgh
Pittsburgh, PA 15260
Tel: (412)624-9245
Fax: (412)624-9163
e-mail: blc+@pitt.edu


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