Re: linear hypothesis

[BFLOOD@SLAC.Stanford.EDU (Bob Flood)]

General comment: this entire thread has provided excellent reading!!!

It is my understanding that the linear, no-threshold model was adopted in
the absence of reliable data as a conservative model on which to base
exposure controls. If my understanding of that philosophy is correct, this
model probably will not change because, as it has been stated on radsafe, a
definitive epidemiological study to decide the issue would require
impossibly large populations to study. While it is reasonable to use the
model to design radiation protection standards, it appears (to me)
inappropriate to use it to estimate individual or collective risk at low doses.

I agree that the BRC approach is most appropriate - I believe that the power
reactor industry purposely stayed out of the original BRC effort because of
fears that industry's poor reputation with the public and intervenors could
result in the BRC effort being perceived as a nuclear power plot of some sort.

My personal suggestion for BRC: 5,000 mrem is the maxmimum dose tolerated by
current regulation. 500 mrem is the level below which no licensee is
required to monitor for occupational exposure. It seems straightforward to
me that, if a licennsee controls doses to less than the threshold at which
monitoring is required, then ALARA has been achieved. If a lower value is
more appropriate for ALARA considerations, how can the 500 mrem monitoring
threshold be justified? The two seems to go together as a set.


>
>Thanks for your 5 points. Yes, the linear hypothesis is used for other
>potentially harmful agents, particularly chemicals, by the EPA
>especially. However, ALARA is not. Just wait until EPA mandates ALARA
>for chemicals. One can't "prove" safety if the background is too high.
>Most chemicals don't have a natural background so it is easier to
>"prove" safety than for radiation where the background gets in the way.
>
>Yes, the debate is about ALARA at BRC doses. I'm suggesting 5 rem per
>year is the BRC dose. Use ALARA ABOVE that value, not below. Then study
>prospectively those whose doses exceed the BRC value to see if there are
>any harmful effects.
>
>The linear hypothesis is NOT scientific interpretation to my mind. It is
>only that, an hypothesis, undemonstrated and with some evidence that it
>is not valid. I was always taught that, when just one piece of data did
>not fit a particular hypothesis (or theory), that one piece of data is
>enough to disprove the hypothesis and the hypothesis should be revised
>or discarded. Is not what others were taught?
>
> The Eagle Alliance was formed to do exactly what you are suggesting,
>tell the public about the benefits of the nuclear industry, among other
>things. Have you read the Declaration of Interdependence? Ask the ANS
>for a copy. By-the-by, does anyone know what the Eagle Alliance is doing
>these days. I haven't seen anything about it since the Summer, 95 ANS
>meeting.
>
>You're right. It is up to us to show the public the benefits of the
>nuclear industry. What would you be willing to do to do that? Al.
>
>*** Reply to note of 10/17/95 11:47
>
>From: David Scherer
>To: RADSAFE --INELMAIL RADSAFE
>
>Subject: Re: linear hypothesis
>I think a few points are in order in this discussion.
>
>(1) The linear hypothesis applies to stochastic risks.  Drug overdoses are
>presumably nonstochastic.  I believe that a linear, non-threshold model is
>used for Pb exposure as the basis of the current drinking water standards,
>so it isn't only radiation.
>
>(2)  Public health rules almost never wait for a potential hazard to be
>proven before they are controlled.  When drugs or medical devices are
>developed, they must be proven to be safe, not the other way around.  The
>onus is not on proving radiation risks.
>
>(3)  The linear hypothesis simply says that risks are observed to be linear
>at high doses, so they should be presumed to be linear at low doses.  A
>simple statement of the state of knowledge and uncertainity.  It seems to me
>that the main rub is not this principle, but its societal application, the
>ALARA principle.  The debate should be this: How do we apply the ALARA
>principle at very low doses?  I think BRC is a sensible approach, somewhere
>in the 10s of mrem/y range.
>
>(4)  I don't think we should play with scientific interpretation to achieve
>changes in ALARA.  Ultimately this approach is likely to be
>counterproductive, especially if the radiation biologists do not sign on.
>Credibility is our only stock in trade.  Environmental groups have it while
>industry does not.  Let's not make matters worse.
>
>(5)  The public does not always demand absolute safety, especially when they
>perceive some benefit from the risk.  In the lower 50, we no longer have a
>national 55 mph (88 km/h) speed limit, even though the death rate is
>expected to rise.  It is our job to show the public and their leaders how
>they benefit from radiation sources, and what the efffects of excessive
>regulation are.
>
>Dave Scherer
>scherer@uiuc.edu
>
>
Bob Flood
Unless otherwise noted, all opinions are mine alone.
(415) 926-3793
bflood@slac.stanford.edu