Re: Radon, smoking and LNT

[epirad@mchsi.com]

Kai,



We considered that factor and are in the process of looking at radon 

concentrations in many of our study homes for a 3rd year.  This is something 

we considered when we set the inclusion criteria for our subjects, the median 

time our subjects lived in the SAME home was 32 years.  



SEE: http://radsci1.home.mchsi.com/irlcs.pdf



The point you bring up is the major reason we are looking at multi year radon 

measurements.  Our findings to date indicate that there is little change when 

someone gets sick in window opening behaviors, home temperature change etc. 

This is also supported by self-reported behavior of window opening etc. in our 

questionnairre data.



We have noted that we do see more change (mixed higher and lower) when someone 

else (For example, a new family) occupies the home other than the the initial 

homeowner family, that is one reason we performed rapid-reporting of lung 

cancer cases in the Iowa Study so that we could get a high percentage of 

living case subjects in the study.  After the initial diagnosis of lung cancer 

for our subjects, we were out at the home placing detectors within a month.



We are further investigating this in Iowa and Missouri through the use of 

glassed based detectors that provide a retrospective assessment of exposure 

over the time period the glass item was in place in the home.  



Nevertheless, recall that in a case-control study, exposure misclassifaction 

will bias toward the null, UNLIKE an ecologic study where misclassification of 

exposure will cause unbounded bias in either the positive or negative 

direction.  



An example of the effects of exposure misclassification can be seen here: 

http://www.aarst.org/news_pdf/2002_IowaU_Follow-up_Study.pdf



Note how poorly even year long basement radon measurments performed.  



In ecologic studies a large proportion of the measurements come from short 

term basement measurments. 



The bottom line is that sparse ecologic data can not adequately capture the 

exposure of interest or control for confounding as further supported by Dr. 

Puskin's paper.  



Bill Field

> You probably missed one of the more important reasons why temporal change in

> radon is less important in your study than in case control:

> 

> Radon concentration in a house is a function of both the properties of the

> house AND the lifestyle of the occupants. (The second factor seems to be

> usually ignored.) In case control studies, the radon measurements in the

> houses of cases are either made when a sick person is occupying the

> premises, or after the cases are no longer living in the houses. In either

> case there is a substantial change in lifestyle, between when the radon

> exposure occurred and when the measurement was done.

> 

> That means that case control studies, almost by definition, are biasing the

> results. The only question is: in which direction and by how much?

> 

> Have any studies been done by how much the radon levels in the living

> quarters change with lifestyle, if no physical changes are made to the

> house? How would the radon levels in the same house compare if the occupants

> were having a party on the patio with the back door open every evening, as

> compared to the radon level in the house with the occupant being sick in bed

> and the doors and windows shut?

> 

> 

> ----- Original Message ----- 

> From: "BERNARD L COHEN" <blc+@pitt.edu>

> To: "Kai Kaletsch" <kai@eic.nu>

> Cc: "RadSafe" <radsafe@list.vanderbilt.edu>

> Sent: Tuesday, July 01, 2003 11:25 AM

> Subject: Re: Radon, smoking and LNT

> 

> 

> >

> > On Tue, 1 Jul 2003, Kai Kaletsch wrote:

> >

> > >

> > > From: "BERNARD L COHEN" <blc+@PITT.EDU>

> > >

> > > > The issue of measuring radon now to explain lung cancers

> > > > presumably due to radon exposures many years ago is present also in

> > > > essentially all case-control studies. I have given reasons why it is

> less

> > > > important in my studies than in case-control stusies.

> > >

> > > Could you please repeat the reasons why the temporal change in radon is

> less

> > > important in your study than in case control? (or give the reference.)

> >

> > --I have used different time periods for lung cancer deaths and

> > they give the same results. I have studied variation of radon levels with

> > age of houses, indicating that radon levels have not changed radically

> > with date of construction. It is more likely that radon level in a given

> > house changes with time than that the county average radon level changes

> > with time -- for example, pathways for radon into and out of the house can

> > change with cracks opening and closing, or with change in ventilation

> > practices like opening windows, etc, but these average out for the county

> > average.

> >

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