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RE: Laymans questions on hormesis and LNT
Ted,
You are missing the point of my argument. What I was
saying is if you declare that it radiation causes DS
breaks are detrimental to cell functions, then you
justified in regulate exposures to prevent DS breaks.
I am saying that you are not. As I said, just because
you can detect an effect does not mean it should be
used as the basis of regulations. Simply stated, DS
breaks can be (1) repaired (2)exist but do not have
effects of cell functions, (3) cause cell death, or
(4) lead to cancerous growths. All are possible, but
only the last should be regulated against. However,
how do differentiate between the DS breaks? I say
regulations should be based on factors other than the
formation of DS breaks.
I think you are looking to defend hormesis without
understanding my comments.
--- Ted Rockwell <tedrock@starpower.net> wrote:
> > if you say that DS breaks are
> detrimental, then we need to control does down to
> those levels.
>
> John:
>
> There are thousands of DS breaks from routine
> metabolism for every DS break
> from radiation. So your conclusion simply doesn't
> follow.
>
> A large part of the problem of discussing radiation
> damage is the fact that
> hormetic behavior is not an anomaly to be explained
> by stretching whatever
> is necessary. Hormesis is the normal response in
> biology, predicted by
> theory and confirmed by laboratory and
> epidemiological data. There simply
> are no good data and no theory showing that LDR is
> harmful. These points
> are specifically conceded in the NCRP and ICRP
> reports, and then the use of
> LNT is recommended for unrelated reasons.
>
> Ted Rockwell
>
> -----Original Message-----
> From: owner-radsafe@list.vanderbilt.edu
> [mailto:owner-radsafe@list.vanderbilt.edu]On Behalf
> Of John Jacobus
> Sent: Friday, August 29, 2003 3:02 PM
> To: Cary Renquist; radsafe@list.vanderbilt.edu
> Subject: Re: Laymans questions on hormesis and LNT
>
>
> Carl,
> I think that this is part of the problem. We are
> able
> to determine DS breaks and observe their repair or
> non-repair. The arguement is the DS breaks are
> precursors to cancer or other effects. I doubt that
> in all cases this is true, whether or not repair
> takes
> place. However, if you say that DS breaks are
> detrimental, then we need to control does down to
> those levels.
>
> Note that hormesis does not even have to be invoked
> in
> this arguement. Yet, it allows more flexibility in
> establishing risk limits.
>
> --- Cary Renquist <crenquis@med.umich.edu> wrote:
> >
> > It seems that experimental techniques are getting
> > down to the level
> > where DSB's and repair processes can be examined
> > quite closely:
> > Mentioned earlier in the year:
> > Rothkamm, K. and M. Lvbrich. 2003. Evidence for
> a
> > lack of DNA double-strand break
> > repair in human cells exposed to very low X-ray
> > doses. Proc. Natl. Acad. Sci. USA,
> >
> > One speculation based on their research is: at low
> > dose rates cells do not attempt to repair DSBs --
> > thus
> > eliminating the chance of an improper repair. Not
> > exactly hormesis, but if that hypothesis stands up
> > under
> > further research it lends credence a dose-response
> > model at variance to the LNT.
> > . . .
>
=====
"May we never confuse honest dissent with disloyal subversion."
Dwight D. Eisenhower
-- John
John Jacobus, MS
Certified Health Physicist
e-mail: crispy_bird@yahoo.com
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