LNT and Epidemiology

["ERIC GOLDIN"<goldinem@songs.sce.com>]

     I'm not an expert in epidemiology (can barely spell it) nor 
     molecular radiation biology, but the discussions of whether 
     recent epidemiological studies of populations exposed to higher 
     background radiation levels does not appear to take into account 
     the possibility that molecular damage from radiation may be 
     different from metabolic radiation damage and below the 
     significance level of epidemiological studies.  I heard an 
     excellent presentation by Dr. John Ward of UC San Diego at the 
     recent BEIR VII meeting in which he described the types of DNA 
     damage from both radiation induced free radicals and from 
     metabolically induced free radicals.  Ward contends that at least 
     some significant percentage of the radiation induced damage is 
     physically different from the spontaneous damage (and he has the 
     molecular biology studies to support this).  These multiply 
     damaged sites are not repaired as easily or effectively as simple 
     damage locations for which routine cellular repair mechanisms 
     operate.
     
     This information tends to say that radiation induced cancers may 
     not be statistically detectable in populations exposed to higher 
     backgrounds or to worker populations who are occupationally 
     exposed, but that there still is some risk.  The question for 
     radiation safety professionals is to optimize the delivery of 
     that risk and ensure that the worker (and the public) is 
     protected from excessive risk.  For myself, I believe that risks 
     even under LNT assumptions at 1E-4 or less are trivial when 
     compared to other factors in our society.
     
     On another related note, the comment is occasionally made that we 
     are spending far too many millions of tax dollars cleaning up 
     sites that present no significant risk to the public.  While it 
     is true that we are spending a fortune that could be used 
     elsewhere, we should keep in mind that there are sometimes good 
     reasons to clean places up.  For example, I heard a presentation 
     a few years ago in which some important oceanographic research 
     relied on the detection of extraordinarily low levels of trace 
     radioactive species (tritium and C-14) in ocean water.  If we 
     don't keep our environment as clean as reasonably achieveable 
     (huh?) then we may render such research impossible.
     
     My opinions only,
     Eric Goldin, CHP
     <goldinem@songs.sce.com>

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