AW: [ RadSafe ] Excess relative risk
Bernard L. Cohen
blc+ at pitt.edu
Tue Feb 12 14:47:57 CST 2008
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."
> 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
> 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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