Re: Radon Exposure Assessment for Cases

[Michael Ford <michaelford@cox-internet.com>]

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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