Rn, Epidemiology + thoron

[Yarmoshenko IV <ivylist@ECKO.URAN.RU>]

Dear Radsafers,

At first, let me thank those of you who began and continue 

the discussion on the radon epidemiology. On my opinion it 

is very important and essential topic. The apparent conflict 

of some studies' results (sure, No 1 is B. Cohen's) and LNT

attracts great attention and bothers all specialists in the field 

of radiation protection.

The arguments against ecological study design itself are still 

unconvincing, though case control design is preferable. It is 

clear that due to statistical power each of the case control 

study along couldn't reject or prove LNT in the radon 

concentration interval of interest. So, the pooling of 

different case control studies should be undertaken. Last 

meta-analysis have been published in 1997 (Jay Lubin and 

Jhon D. Boice, Jr.), it included eight studies (4263 cases and 

6612 controls). Since 1997 the list of radon and lung cancer 

case control studies have broadened up to 18 (at least)

and now includes about 11 000 cases and about 19 000 

controls (my assessment). I believe new meta-analysis could 

be performed quickly.



Another point which I would like add to the discussion is 

thoron. Usually researchers doesn't consider thoron progeny 

exposure at all (both in case control and ecological studies). 

I think it is not quite well-founded. According to 

UNSCEAR Report world average thoron equilibrium 

equivalent concentration is 0.3 Bq/m3 and range of average 

concentration by surveys is 0.2-12 Bq/m3. These values 

seems to be negligible. But I think it is negligible for 

radiation protection purposes but not for epidemiological 

studies. Exposure to 1 Bq/m3 of thoron EEC is equivalent to 

about 12 Bq/m3 of radon concentration (1*5/0.4). Such 

thoron EEC can substantially change the distribution of 

subjects by intervals of exposure, especially in low range of 

exposure, and consequently bias the results.





Ilia Yarmoshenko

Radiation Laboratory

Institute of Industrial Ecology

Ekaterinburg

Russia





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