Radon and Lung Cancer: What the studies really say.

[Kai Kaletsch <eic@shaw.ca>]

Friends,



We are all aware that ecological studies, in general, have some limitations.

Similarly, many of the case control studies have some very specific

problems. Both of these issues have been discussed (some would say ad

infinitum) on this board and elsewhere.



For this thread, I'd like to assume that the authors of both types of study

know their craft and are able to collect data and make some very basic

adjustments and stratifications. The studies then tell us:



1. People living in counties that have high average radon concentrations

have fewer lung cancers than people living in counties where the average

radon concentration is lower do.

2. People who had high cumulative radon exposures in the past have more lung

cancers than people who have been exposed less do.



Some people have stated that the conclusions that follow from these

statements cannot both be right. Clearly, this is wrong. There is probably

an infinite number of dose response functions that are consistent with both

observations. None of these functions requires the presence of hidden

confounders. The obvious one that I can think of is:



--> High radon in your own house is bad for you and high radon in your

neighbor's house is good for you.



Radon in your own house represents chronic exposure and high radon in your

own house will result in a high cumulative exposure. On the other hand, you

are only exposed to the radon in your neighbor's house for a few hours at a

time.



Is there any reason why we should assume that the beneficial effects of

radiation exposure are dependent on cumulative dose? Can anyone name a

beneficial agent where the amount of benefit is related to cumulative dose

alone? Other beneficial stressors (e.g. exercise) deliver their benefit most

effectively if the stressor is applied for a short time and is followed by a

period of relaxation. This is exactly the temporal variation in radon

exposure that someone living in a low radon house in a high radon county

would experience.



Kai

http://www.eic.nu



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