Re: Radon Exposure Assessment for Cases

[Kai Kaletsch <info@eic.nu>]

Don,



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

> winters and hot summers.



Not unlike Saskatchewan (it is -22C here right now, what is the temperature

in Iowa?). Even receiving a visitor or going outside can add to the number

of air changes. When the temperature difference between inside and outside

is 40 to 50C, the air just wants to rush out as soon as the door is opened.



When too many smokers come to visit, I will turn on the bathroom fan to

increase ventilation.



Most activities around the house will increase the number of air changes:

cooking - if you have a range fan, laundry - if your dryer is vented to the

outside, vacuuming - if you have a central vacuum. I would think that sick

people would do less around the house.



> So there are closed-house conditions during most

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



I usually have the doors closed during the day, but open them at night. When

I'm constantly going between inside and outside, I might just leave the

doors open.



> 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.



Yes.



> Someone could think up any what if,

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



Assuming that someone with lung cancer has the same lifestyle as someone

without, seems to be a pretty big "what if".



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



I would do it fairly similar to the Iowa study, if I were to do it

case-control. If I was to do an ecological study, I'd do it much like Dr.

Cohen. That's the problem. Now I'm stuck with 2 sets of data that, at least

on surface, seem to disagree.



Don, how do you explain the fact that cases and controls had similar radon

levels in the basement (actually controls had slightly higher levels), but

cases had higher levels in the living areas?



If cumulative radon exposure was really the causal factor, I would expect at

least some excess cases to be caused by a high radon source term (high

basement reading). What the data seems to suggest, however, is that all the

excess cases are due to poor ventilation (small difference between basement

and living areas).



Kai





> >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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