AW: [ RadSafe ] Excess relative risk

Tue Feb 12 18:44:37 CST 2008

Great reply, Professor Cohen.  I'm pleasantly reminded of the best rejoinder
I ever saw on RadSafe.  One that you provided about 10 years ago, and I
paraphrase now:

University of Iowa epidemiology grad student:  "Your method violates
Epidemiology 101."

Prof Cohen:  "I am bound by the Scientific Method, not Epidemiology 101."

I'm still waiting for the opportunity to use a similar line myself. 

Brent Rogers

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
Of Bernard L. Cohen
Sent: Wednesday, 13 February 2008 7:48 AM
To: John Jacobus
Cc: Rainer.Facius at dlr.de; radsafe at radlab.nl
Subject: Re: AW: [ RadSafe ] Excess relative risk

    I hope this does not sound too radical: In my experience, 
epidemiologists are not *scientists* in the broad sense of that term. 
They practice a *technology* which has been "boxed" and they are not 
willing to think outside that box. For any new ideas or approaches, it 
is "their way or the highway"; they reject them with only the shallowest 
reasoning, or more commonly ignore them. That is not the way scientists 
have traditionally operated. If physicists operated that way, we would 
never have had quantum theory, relativity, or any of the many great 
advances of 20th century physics.
    Their box has been successful in many applications, but it is prone 
to failure where statistics are marginal or where there can be multiple 
confounding factors. They customarily treat the latter with multiple 
regression analysis which is fraught with dangers -- they call this 
"adjusting for confounding factors", factors they select with something 
less than air-tight reasoning.
    If 2 or 3 epidemiologists take a position, a "consensus" forms 
without those who constitute the consensus spending any time or thought 
on the subject. They just don't like to think outside their box. They 
seem to have no experience in doing that.

John Jacobus wrote:
> One of the purposes of a skeptic is not so much to challenge as to present
what is unknown.  
>    
>   I have been accussed of being silent.  I am not an epidemiologist, so I
have to relie on those who are recognized experts. (If you choose to ignore
the conclusion of experts, that is your choice.)   The consensus has been
that there are no demonstracted effects below 100 mSv.  Neither harmful or
beneficial.  All studies are individual pieces of a puzzle.  To date, the
well-known epidemiologists have reached the conclusion stated above.
Individual studies may support your position or mine, but the concensus has
always remained the same.   
>    
>   Your uncited comments below are interesting, but how do they fit in the
overall study of radiation effects?  I have seen some studies that do show
negative slopes.  We can all cherry pick the data that supports our
positions, but what do the experts say?  
>    
>   
>
> Rainer.Facius at dlr.de wrote:
>   "Of course, there is no proof of negative excess risk."
>
> John:
>
> Your silence regarding several invitations to name/present what YOU
consider the best proof of a positive excess relative risk for cancer also
supports the reverse statement (with respect to your appraisal at least):
>
> "Of course, there is no proof of positive excess risk." 
>
> (for chronic low dose exposures up to around 600 mSv; for acute exposures
such as the ATB survivors, peer reviewed published analyses demonstrate that
even these data are compatible with 'no effect' up to about 200 mSv) 
>
> By the way, you have been confronted here with data plots from half a
dozen or so epidemiological studies of human (not to speak of animal
laboratory experiments) cancer induction (lung cancer comes to my mind as
well as the breast cancer incidence in babies which have been treated for
hemangioma) which exhibit (sometimes marked) negative slopes in the initial
dose region.
>
> Part of the discrepancy appears to reside in what you are inclined to
accept as 'proof'.
>
> Kind regards, Rainer 
>
> Dr. Rainer Facius
> German Aerospace Center
> Institute of Aerospace Medicine
> Linder Hoehe
> 51147 Koeln
> GERMANY
> Voice: +49 2203 601 3147 or 3150
> FAX: +49 2203 61970
>
> -----Ursprüngliche Nachricht-----
> Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im
Auftrag von John Jacobus
> Gesendet: Samstag, 26. Januar 2008 23:09
> An: howard long; Otto G. Raabe; radsafe at radlab.nl
> Betreff: Re: [ RadSafe ] Excess relative risk
>
> Of course, there is no proof of negative excess risk. 
>
>
> howard long wrote:
> What would make clear in that formula that kD is a NEGATIVE excess
relative risk when radiation exposure is under ~20cGy (rad), rapid rate,
i.e. hormesis? +-kD?
>
> Howard Long
>
>
>
> +++++++++++++++++++
> "If history teaches any lesson it is that no nation has an inherent right
to greatness.  Greatness has to be earned and continually re-earned."
> - Norman Augustine, Chairman of the National Academies Committee 
>
> -- John
> John Jacobus, MS
> Certified Health Physicist
> e-mail:  crispy_bird at yahoo.com
>        
> ---------------------------------
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>   

-- 
Bernard L. Cohen
Physics Dept., University of Pittsburgh
Pittsburgh, PA 15260
Tel: (412)624-9245  Fax: (412)624-9163
e-mail: blc at pitt.edu  web site: http://www.phyast.pitt.edu/~blc

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