RE: Pooled studies and their increased sensitivity--is it real? / Mobile phones

["Bjorn Cedervall" <bcradsafers@HOTMAIL.COM>]

If there is a non-causal association between two factors (say between 

ashtrays and lung cancer in a town) and then a pooled analysis is done for 

the whole country - this should reasonably result in a stronger (non-causal) 

association: Or to word it differently - the methodological problem will be 

amplified but you will still be suspecting the wrong thing. If ten research 

groups are doing an experiment in the wrong way - pooling of the data won't 

help. Repetition of mistakes is always a potential threat.



The "EMF"-leukemia paper from BMJ  2000 - I have read it and there are 

appropriate reservations at the end of the discussion. Some people may 

interpret this as "leukemias can be caused by power lines etc" but the hot 

dog study (Cancer Causes and Control, 1994) is still there as a symbol of 

the real character of the problem.



Two of the authors of the BMJ paper from 2000 were also involved in the 

mobile phone alarm (massive international pressrelease) two months ago. I 

trust them in what they are doing (as opposed to other actors in the field) 

but I don't understand why they run to the massmedia with such shaky 

statistics as that in the recent moble phone alarm. They were also out in 

the media with the powerline paper in 1992 - based on seven extra childhood 

leukemias over a 25 yr period in Sweden. For the highest exposure category 

(0.4 microT or above) it was zero extra cases - few people seem to have 

noticed that. I have nothing personal against these individuals - I just 

don't understand the ethics in running to the media with shaky statistics - 

even strong associations can be non-causal and I am sure that they know 

that.



I still bet a whole dime that it hadn't been significant in any sense if 2-3 

cases (benign acoustic neurinomas) had been swapped (very large 95 % 

confidence interval for OR, slightly lower (probably not statistically 

significant) incidence of neurinomas than expected on the opposite side 

(mobile phone side) of the head).



To me, that study says that 1/ Mobile phones are much more probably "safe" 

than not 2/ That it may be questioned whether these types of studies are 

possible to do - simply because of the problem with recall bias etc.



My personal reflections only,



Bjorn Cedervall    bcradsafers@hotmail.com





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