Re: HPS Objective

[rkathren@tricity.wsu.edu (Ron L. Kathren)]

David Lee is absolutely right in arguing for what is effectively a de
minimis level to go along with ALARA-- but 600-900 rem per year ???!!! [I
think you meant mrem].  In any, de minimis levels of varying amounts have
been proposed, sometimes under different names (eg the NIRL of the NCRP).
Again, in establishing a de minimis value, prudence should dictate.  Perhaps
the question, paraphrashing what Robley Evans asked when setting the radium
MPBB back about 1941 (many years, of course, before most of us were born) --
should be:  would you let your children (or, for those born before Evans
asked, your grandchildren) be exposed to that level?  or your unborn child?
Or for contamination, would you let you kids play in it?  We also have to
remember that de minimis exclusions could be additive:  in other words, if
100 mrem per year is the accepted level, how do I get protected from 20 or
even 10 individual de minimis exposures, which could result an annual dose
of several rem.  The problem is more complex than we sometimes realize but
nonetheless I think if we honestly answer these types of questions, we might
come to some reasonable concensus.  I for one would urge the adoption (and
have done so in a number of publications)of a modest de minimis level for
regulatory application.

Ron Kathren

        At 02:49 PM 8/8/97 -0500, David W. Lee wrote:
>At 09:42 AM 08-08-97 -0500, you wrote:
>I have a question for those who have suggested that there should be no
>control over exposures below those where acute harm has been directly
>observed:  Why not?  Put another way, what are the reasons for releasing
>control?  Ron has given his reason for ALARA: prudence.  What are yours?
>
>Dave Scherer
>scherer@uiuc.edu
>
>
>
>	Ron Kathern responded in part: "...given the fact that our knowledge of
>potential low level radiation effects is at best incomplete, prudence would
>dictate that we eliminate such unnecessary exposures, even if we cannot say
>with absolute certainty that there will be a discernable detrimental effect
>attributable to them.  This is the essence of ALARA...."
>
>	As exemplified by the historical shoe-fitting fluoroscope issue, and one
>can certainly think of other "unnecessary" exposures that did not involve
>nearly as much exposure/dose, some may consider it "prudent" to eliminate
>such an "unnecessary" exposure under the ALARA philosophy purely because it
>is "unnecessary."  Those who adopt such a school of thought, however, must
>then be willing to specify a lower dose/exposure level below which they
>will no longer be such an ALARA zealot.
>
>	Thus a question back to David Scherer:  How low-level must the exposure
>rate or dose be before you declare an "unnecessary" exposure to be so
>trivial as to not concern yourself with it anymore?  The point being that
>if you are going to go after an "unnecessary" exposure, there ought to be
>some point at which one quits playing Don Quixote chasing after and
>jousting with a few hundred millrem sustained either episodically or
>non-acutely.
>
>	I think those who wish to zealously stamp out or reduce "unnecessary"
>exposure should be accommodated, but I would suggest that the level at
>which even they should call things "good enough" ought to be a reasonable
>multiple of the mean, chronic natural radiation background dose which each
>of us unavoidably sustains and to which we do not apply the ALARA
>philosophy.  The NCRP would have us believe that the total mean background
>dose is approximately 300 mrem, effective dose from radon included, from
>which no "harmful" effects have been observed.  Since the terrestrial
>portion of the background dose can be as high as 10 times the mean
>terrestrial level in certain regions of the world and the effective dose
>from radon is even more variable geographically, two to three times the
>mean background dose puts you in the neighborhood of 600--900 mrem/year.
>
>	I would suggest that it is no longer "prudent" to expend significant
>radiation safety effort on radiation producing device or radioactive
>material use operations that impart less than 600--900 rem/yr.  What is the
>benefit to society by expending such effort below this level?  Example:
>What is really gained by providing individual dosimetry to radiation
>workers who routinely sustain on an annual basis less than the dose that
>they will unavoidably sustain from the natural background?
>
>	The ALARA Radsafers are now invited to have fun declaring me to be a heretic.
>David W. Lee
>Los Alamos National Laboratory
>Radiation Protection Services Group (ESH-12)
>PO Box 1663, MS K483
>Los Alamos, NM  87545
>PH:   (505) 667-8085
>FAX:  (505) 667-9726
>lee_david_w@lanl.gov
>
>