Re: One pound of Plutonium -Reply

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

You pose a very good question regarding the application of a threshold, but
before addressing the question one needs to recognize that the response
curve is different for different end points.  That, of course is why we have
different risk coefficients for different cancers and both deterministic and
nondeterministic effects.

As I pointed out in my Hartman lecture, radiation response (all end points
combined) is likely to be Gompertzian (ie sigmoidal).  If we consider only
low level nondeterministic effects, why not use the LNT realizing in the
process that it is a conservative approach in that it overestimates the
risk, but also have a lower level 'de minimis' risk based cutoff below which
we do not regulate.  For my money, this de minimis risk level could be on
the order of 10E-6 to 10E-5 per year, which over a lifetime of 70 years and
not considering or adjusting for any latency period, would give a total
lifetime risk of 7 in 10,000 (0.0007) to 7 in 1,000 (0.007).

I am preparing for the onslaught of responses that the above is sure to
generate.

Ron Kathren (AKA as "and all"?)

 At 11:53 AM 3/23/98 -0600, ABELQUIE@ORAU.GOV wrote:
>Dear Otto and all:
>
>I have been keeping abreast of the LN-T argument for many months on
>Radsafe.  I  have no direct experience to base my opinion for or against
>the LN-T hypothesis.  I rely on the merits (based on my perception)  of
>each side of this argument.  It appears to me that it is likely that a
>threshold exists.  So, for sake of argument, let's say that a threshold
>does exist---How do the regulators apply it?  I posed this same question
>to Keith Dinger last week and his quick reply was "set limit at 10% of
>threshold".  I'd appreciate other  thoughts on this.
>
>In your example below, the threshold is 1 Gy lifetime dose for Pu.  Let's
>assume that a threshold for penetrating radiation is shown to exist at 25
>rem - the problem is, how do the regulators implement this "scientific
>fact" (existence of a threshold)?   Do we ever expect to know what the
>probability of fatal cancers are once the threshold is exceeded?  Do we
>consider the 300 or so mrem/y from background as contributing to the
>lifetime dose?  I think that once a threshold is proven to exist, people will
>want to spend sufficient resources to be assured that they will have a
>very small chance of exceeding the threshold.  Thus, I believe that even
>if LN-T soon goes away, we will still have ALARA - but I believe a much
>more reasonable form of ALARA (i.e not having to spend $$millions to
>reduce mrem).   It would be nice to hear some discussion from the
>Radsafe community on this.      
>
>
> D1.OUT."ograabe@ucdavis.edu" 03/23/98 11:17am >>>
>
>March 23, 1998
>Davis, CA
>
>Dear Jesse and all:
>
>There is no truth to ANY risk factor in FGR 13. Your use of FGR 13 in
>your
>calculation makes totally invalid the result that you got. I have
>previously estimated that there is an effective threshold for
>radiation-induced lung cancer from plutonium at about 1 Gy lifetime dose
>(HPJ 57, Suppl 1, 419-432, 1989). The Russians found that no one with
>lifetime lung doses below 0.8 Gy developed radiation-induced lung
>cancer
>(HPJ, Dec. 1997). FGR 13 will never give you a correct answer since the
>whole document is based on an imaginary linear risk relationships that
>have
>no basis in reality.
>
>Otto
>                *****************************************************
>                Prof. Otto G. Raabe, Ph.D., CHP
>                [President, Health Physics Society, 1997-1998]
>                Institute of Toxicology & Environmental Health (ITEH)
>                     (Street address: Old Davis Road)
>                University of California, Davis, CA 95616
>                Phone: 530-752-7754  FAX: 530-758-6140 [NEW AREA CODE]
>                E-mail ograabe@ucdavis.edu
>
>