RE Useful Dental X-Rays

[Joyce Davis <JOYCED@DNFSB.GOV>]

RE  Useful Dental X-Rays

>>> "Dr. Marvin Goldman" <mgoldman@ucdavis.edu> 10/30/97 07:13pm >>>
in response to Messrs. Rima and Tschaeche wrote:
....
The ranting on low level risks seems never to abate.  We all know
that the science of molecular biology still has given us no direct proof of
cancer risk (and it's only cancer risk in this debate), even though some
induced genetic and molecular markers in today's literature may be steps on
the way to a full understanding of all the mechanistic pathways and steps
from dose absorption to cancer manifestation.  Nor can anyone with any
understanding of epidemiology expect that epidemioogical approach can ever
show the risk from millirem sized doses even if the ICRP coefficients are
correct.   When it come to a religious belief level of discourse, rather
than objectiviely  interpreting a science data set, we all lose
credibility.

	The absence of "bodies in the street" proves nothing when dealing
with minute probabilistic risks.  For what it's worth, I have no problem
with the linear, no-threshold hypothesis as a model for regulatory policy.
I do have a problem with those who selectively plot data points along a
straight line and insist that it confirms the linear proportional risk
coefficient down to the last photon.  Counting "hypothetical bodies" at
microSv exposures is a way to play with collective doses, but it's not real
nor realistic.  Biology  just does not work that way, and in due course the
window of insight will open.  Sadly, support for the research to speed up
the opening of that window is limited, so we may have to be patient.  Until
then, I for one am satisfied with the conservative LNT philosophy, but not
the further subfractionation of the limits to ridiculous  operational micro
compartments.  As for the "true risk", to me at this time, the universal
curve of risk still looks sigmoid, with the region from about 0.1-0.2 Sv to
1-3 Sv appearing to be fairly linear.  Period!

	I realize that each of us has an opinion, that most are not ready
to change their opinion, and that  if the data were really there, this
issue might actually be settled, (if an issue can be said to ever be truly
settled).  It's not a matter of being an "old man worried that he might be
wrong", but whether the cold scientific data are tight enough.  To which
this old scientist says the data are good, but still not tight enough. I'd
welcome seeing an increase in the research dollars rather than substituting
an increase in reactive decibels.  But then I'm only one voice.

Marvin Goldman
mgoldman@ucdavis.edu
-------------------------------------------

I'd like to add my voice to Dr. Goldman's.  And I hope there are many of us in the rational middle of this sometimes
irrational muddle.  LNT is neither holy writ nor the devil's doing.  Sincere and thoughtful people can, and do, differ. 
Let's cool it and proceed with the work of wresting her secrets from Mother Nature and, in the meantime,
protecting people from harm based on less than perfect information.

Only the opinion of J P Davis
joyced@dnfsb.gov