Steve Frey:
Cohen’s data are certainly not worthless! As I have previously mentioned, Cohen’s study is probably the largest and most thoroughly analyzed ecological study of any kind. Much can be learned from Cohen’s extensive analysis of data from 1600 U.S. counties. My concern is that restraint needs to be exercised in interpreting the data. For instance, many hormesis proponents use Cohen’s data. Even Cohen cautions that his data should not be used to support hormesis.
Ecological studies, such as Cohen’s, are only suggestive of functional relationships for reasons that have been described in the technical literature and on RadSafe ad nauseum. The true test of LNT or other predictive theories is case-control or cohort studies that properly account for the effect of confounding variables at the individual level. Cohen’s data suggests that LNT fails at radon levels less than 150 Bqm-3. A number of published case control studies and meta-analyses of case control studies do not support Cohen’s interpretation but instead are consistent with LNT.
Cohen has offered a monetary reward to anyone who can explain this discrepancy. As I have previously mentioned, this is backwards. Cohen insists his interpretation of the ecological data is correct; accordingly, it is incumbent upon Cohen to show that the case-control studies are wrong (i.e., the case-control derived risk coefficients should be negative at radon concentrations below 150 Bqm-3 ). Cohen has failed to do so to date.
Ken Mossman