regulatory use of LNT

["Les Slaback, Health Physics" <SLABACK@micf.nist.gov>]

This reminder is probably unnecessary, but I offer it anyway.                   
                                                                                
The regulatory use of the Linear-No-Threshold model is just a conservative      
usage of a semi-defensible approach for setting a priori limits.                
                                                                                
It is not the same as projecting after-the-fact effects, which is what most     
of the past discussion condemns.                                                
                                                                                
Using LNT (or whatever model one can justify) to project a limit that           
represents a reasonable risk level, however uncertain, is the classical         
safety model.  What has differentiated the radiation arena is the use of        
Optimization (ALARA) on top of the limit.  It would seem that most of the       
arguments about model uncertain impact the validity of the application of       
the Optimization principle, and possibly the setting of limits                  
for the public different from those of workers.                                 
                                                                                
Another issue that complicates this discussion is individual sensitivity.       
If one sets limits based on the most sensitive members of the population,       
the issue of genetic sensitivity may drive the limits even lower than they are  
now.                                                                            
                                                                                
Having said that, I find it difficult to believe that anyone will ever be       
able to defend the regulatory controls that EPA has mandated at the             
0.1 mrem per year level for airborne releases.                                  
                                                                                
SLABACK@MICF.NIST.GOV                                                           
   ...a little risk, like a bit of spice, adds flavor to life                   
                                                                               
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