Re: Radon Exposure Assessment for Cases

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

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

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

>increase ventilation.





Kai, interesting comments.

I doubt people would come to visit people with lung cancer and then smoke, 

so they would have less ventilation than controls, right?





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

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



I think Iowa did some second and third year radon measurements when the 

subjects became more ill, they reported the year to year variation in the 

paper.  They could probably look at that.  But, remember, there are other 

people living in the house so the lifestyle factors may not be all that 

different.



This is likely more of a problem in studies like Martin's where they go back 

to houses, to measure radon, that have not been occupied by the subject for 

many years.  It would be interesting to hear how many of the homes in 

Martin's study are occupied by the subject when they performed the radon 

measurements.  In the Iowa study, the data looked like there was more of a 

change in radon where houses were now occupied just by next of kin.  Can you 

imagine the changes that occur in homeowner behaviours from one family to 

the next?  I think this is why the Iowa Study tried to maximize the number 

of living subjects.

>

>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?



I think your talking about the geometric mean levels? I don't know how much 

averaged data will tell you. I am more interested in the cumulative 

exposures weighted by how much time was spent in the house.  Didn't they do 

a risk plot if just basement measurements were used?  I recall it still 

showing an upward direction.  No one spends time in the basement so that 

information is not that informative about risk.



How would I explain it?  It looks like the controls had slightly larger 

houses (more cubic feet) so there could possibly be more dilution of the 

radon in the upper floors.  Who knows, I would not put to much emphasis on 

averaged data.



>

>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).





The subjects spent very little time in the basements so that is really not a 

significant factor.  You are also may be ignoring the fact the WLMs were 

linked to where the subject spent time within the home and how much time was 

spent in the home.  After all, exposure = time at a certain concentration.





I understand the challenge of trying to decide between Cohen's data and the 

Iowa Data.  I think the suggestion Dr. Field made to Dr. Cohen would help to 

improve the quality of his analysis.



Don



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