Re: Iowa Radon Lung Cancer Study

[FIELDRW@aol.com]

Otto,

I appreciate your interest in the study.  

1) The cross-level bias you refer to is more of a problem in ecologic studies 
where you do not have information at the individual level.  Nonetheless, 
"adjusted for smoking" could be exchanged for "controlled for smoking" in the 
sentence you refer to.

Obviously, cases (subjects with lung cancer) generally have smoked more than 
the  controls (subjects without lung cancer).   Some researchers use 
randomized recruitment procedures to enroll more smoking controls.  However, 
when you do a population based case-control study (as we performed), you must 
be sure not to OVER MATCH the controls to the cases.  The inclusion criteria 
for cases and controls we used are listed at the web site for the study.  In 
any case, the smoking histories for the controls do not have to be matched to 
the cases to the extent you describe in order to adjust (or control) for 
smoking.  

2) Otto, regarding your question "I was surprised to learn from your short 
summary that Iowa has the highest radon levels in homes of any State".  

Iowa was an ideal place to perform a study looking at the risk posed by 
residential radon exposure for several reasons:  1) Iowa has the highest MEAN 
radon concentrations in the United States;  2) women in Iowa tend to stay in 
the same home for long periods of time; and 3) Iowa has a high quality 
(NCI-SEER) Cancer Registry, which allowed rapid-reporting of lung cancer 
cases.  

Ironically, the highest regional (group of counties) radon concentrations are 
reportedly the 6 counties that surround Three Mile Island.  I would guess, 
Pennsylvania may have the greatest population (in the U.S.) at risk from 
residential radon exposure.  Maybe, someone from Pennsylvania (possibly Drs. 
Kirk or Cohen?) could comment on that.  This region includes Lancaster County 
where I grew up.  It seems I have a hard time getting away from radon.

I will send you a copy of the Iowa findings paper (Phase 1) as you requested 
via private email.  It discusses the exposure assessment and presents 
detailed information concerning the range of exposures.

Please email me directly at bill-field@uiowa.edu if you have additional 
questions.  As you can understand, I sometimes do not catch all the personal 
emails that are addressed to me that go to the address where I receive my 
Radsafe and Riskanal postings.  I skim through the subject headings pretty 
quickly.

Regards, Bill 


R. William Field, Ph.D.
Department of Epidemiology
Department of Occupational and Environmental Health
College of Public Health
N222 Oakdale Hall
University of Iowa
Iowa City, Iowa 52245

319-335-4413 (phone)
319-335-4748 (fax)
mailto:bill-field@uiowa.edu



 
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