Nonlinear alphas and Other Stuff

[Joyce Davis <JOYCED@DNFSB.GOV>]

I think David Scherer has raised an interesting point about the use
of dose equivalent.   Dose equivalent is not a physical unit.  It is
a practical unit developed to permit the adding of apples and
oranges.  It is very useful in practical control of exposures in
mixed fields.  When we talk about the science of radiation effects we
should be talking rads (or maybe even microdosimetric quantities) of
particular types and energies of radiation to particular organs.  The
rem is useful as a simplified unit for public consumption but we
should refrain from manipulating it in scientific models and
calculations of any but the most simple (simplistic) kind.  
And don't get me started on effective dose!  Again for practical
purposes it is nice to be able to estimate the combined effect of
internal and external doses; but we must recognize that these
effective rems are even further removed from physical quantities. 
The weighting factors developed are based on "risk" -- but we know
risks are uncertain (unknown?) at low doses.
In my opinion HPs should  use rems when convenient for the good
practical purposes for which they were developed -- control of
occupational exposures.  They are indexes which have some rather
arbitrary features.  We should not be discussing the science of
health physics in terms of rems.  I think it's in the "weighting
factors" that much of the scientific controversy and misunderstanding
that pervade the current controversy arises.
(I'm of the old school; please substitute Sieverts for rems if you're
one of the more up-to-date guys.)
J P Davis
joyced@dnfsb.gov