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Re: Laymans questions on hormesis and LNT
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. Löbrich. 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.
Cary
>>> John Jacobus <crispy_bird@YAHOO.COM> 08/28/2003 08:04:20 >>>
Barbara,
While this is true by definition, I doubt if it is
true in biology. The result will depending on the
endpoint you study, whether it the production of
double-strand breaks, activation of repair enzymes,
etc. To me, the real test should be the
epidemiological evaluation of populations. As noted
in many of the discussion on this list, the results
are based on projecting high dose results to low dose
levels where reliable results are hard to extract.
--- BLHamrick@AOL.COM wrote:
> In a message dated 8/27/2003 5:13:58 PM Pacific
> Standard Time, tgi@cit.bg
> writes:
> If hormesis means provoking some self-defence
> reaction of the body by
> means of something it recognizes as harmful, why
> would hormesis and LNT
> be mutually exclusive?
> Because the LNT assumes that any radiation dose
> above zero (including
> background radiation) delivers some measure of harm,
> with no commensurate or
> overriding benefit. Hormesis proposes that within
> some range a low dose of radiation
> actually provides an overall beneficial effect.
>
> Barbara
>
=====
-- John
John Jacobus, MS
Certified Health Physicist
e-mail: crispy_bird@yahoo.com
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