Re: Radon Exposure Assessment for Cases

["Rad health" <healthrad@HOTMAIL.COM>]

Michael,



The paper states that these were homes where people lived for an average of 

32 years so these are not homes all just built 20 years ago.



Don





>From: Michael Ford <michaelford@cox-internet.com>

>Reply-To: Michael Ford <michaelford@cox-internet.com>

>To: RADSAFE <radsafe@list.vanderbilt.edu>

>Subject: Re: Radon Exposure Assessment for Cases

>Date: Sat, 26 Jan 2002 12:43:18 -0600

>

>Don,

>

>Do you maintain that structure of these houses are as air-tight as they 

>were

>20 years ago?

>

>I would maintain that as houses age, they tend to settle and and the

>structure loosens up and allows more exchange with outside air (i.e., less

>energy efficient).

>

>As such, the assumption that a one or two year average radon concentration

>represents the actual average concentration for the prior 20 years requires

>a high degree of validation.  "Tighter" houses would have higher radon

>concentrations early on.  Such an approach might lead to the

>under-estimation of radon exposures.

>

>v/r

>Michael

>

>

>on 1/26/02 12:08 AM, Rad health at healthrad@HOTMAIL.COM wrote:

>

> >

> > Kai,

> >

> > Do you have any evidence to support that?  Remember, Iowa has very long

> > winters and hot summers.  So there are closed-house conditions during 

>most

> > of the year including summer when air conditioning is very common. The

> > glass-based measurements used in the Iowa Study will reflect the radon

> > concentrations over the 20 years the subjects lived in the home so that 

>will

> > be a check of that. In addition, women tend to become chilled more with 

>age,

> > right?  But, then they adjusted for age. Someone could think up any what 

>if,

> > but I have seen no supporting data to back up the any of the what ifs.

> >

> > To take care of all the what ifs someone could propose to put people in 

>a

> > exposure chamber and expose 100 people to radon and 100 to no radon.  

>They

> > could live in the chambers for 80 years and then we would know for sure,

> > right?

> >

> > Kai, how would you design a residential radon epidemiology study?

> >

> > Don

> >

> >> From: Kai Kaletsch <info@eic.nu>

> >> Reply-To: Kai Kaletsch <info@eic.nu>

> >> To: RadSafe <radsafe@list.vanderbilt.edu>

> >> Subject: Radon Exposure Assessment for Cases

> >> Date: Fri, 25 Jan 2002 23:43:30 -0600

> >>

> >> The misconception, that radon gas concentrations are a property of the

> >> house, could be affecting the results of case-control studies.

> >>

> >> Radon concentrations are a function of source term and ventilation 

>rate.

> >> Ventilation rate is, in part, related to the lifestyle of the 

>occupants. As

> >> I understand it, case-control studies use radon measurements, performed

> >> after diagnosis, to infer the radon exposure of the patient before lung

> >> cancer diagnosis.

> >>

> >> Is it really reasonable to assume that a sick ex-smoker has the same

> >> lifestyle as a healthy smoker? I would think that a healthy smoker 

>would

> >> tend to have the doors and windows open more often than a sick 

>ex-smoker.

> >> This would lead to overestimating radon exposures for cases and could

> >> produce a positive association between radon and lung cancer.

> >>

> >> This mechanism would affect most case-control radon studies. The Iowa 

>study

> >> shows the average radon concentrations for the basements and first and

> >> second levels for both cases and controls. The controls actually had 

>higher

> >> radon levels in the basements, while cases had higher radon levels in 

>the

> >> living quarters.

> >>

> >> I would think that the basement concentrations are more indicative of 

>the

> >> source term, while the upper level readings would be more a function of

> >> lifestyle.

> >>

> >> Kai

> >>

> >> PS: Before I get flamed too badly: I am not out to trash anybody's

> >> research, but it is important to understand the limitations of all the 

>data

> >> that's out there. The correct theory will explain all data to within 

>these

> >> limitations.

> >>

> >

> >

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