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RE: low level radiation article
Hi,
As a non-expert, I would like to share some personnal thought for the sake
of some critical thinking on the subject.
I read this article a short while back with much interest. Clearly, care is
in order when trying to extrapolate from the results of studies on
individual cells in relative isolation. In particular, this article does not
necessarily contradict the possibility of hormesis, in my personal opinion.
The explanation of the findings, as proposed by the authors, is that the
body's survival mechanism may be to induce the double-strand break
(ds-break) dammaged cells to die when the number of cells so-dammaged is low
rather than attempting repair. In the case of high-doses, the survival
mechanism becomes one of (ds-break) DNA repair as the number of dammaged
cells is too great, suggesting a threshold level of dammage above which
ds-break repair takes place. This is in contrast to current models of risk
assessment which assume that DNA repair efficiency is independent of dose.
As such, this study suggests that cell repair of ds-breaks is slower at low
doses - but that is all. This implies that low levels of radiation are more
dangerous than high doses to individual cells, but not necessarily to the
organism as a whole. It is not inconceivable that shedding these weak or
dammaged cells, as described, provides a hormedic effect for the organism as
a whole.
Best regards,
Grant
> -----Original Message-----
> From: Michael C. Baker [SMTP:mcbaker@LANL.GOV]
> Sent: Thursday, May 08, 2003 8:40 AM
> To: radsafe@list.vanderbilt.edu
> Subject: low level radiation article
>
>
> From USA Today's web site.
>
> Mike
>
>
>
>
> Posted 5/7/2003 9:39 PM
>
> Study: Lowest-level radiation is more damaging than thought
> By Dan Vergano, USA TODAY
>
> Radiation may damage living cells at surprisingly low energy levels,
> challenging scientific beliefs about the levels of radiation likely
> to prove deadly.
>
> The study by a team of European researchers found unexpected
> molecular reactions to low-energy radiation that suggests it may play
> a greater role in causing cancers than originally thought. It also
> suggests a possible new route for cancer treatments.
>
> Although ultraviolet rays in sunlight are known to cause skin cancer,
> the health effects of other low-energy, or "non-ionizing," radiation
> from cell phones or electrical wires is a controversial subject.
>
> High-energy radiation, as in X-rays, that damages cells by
> "ionizing," or electrically exciting, molecules is a well-established
> cause of cancer.
>
> In Wednesday's Physical Review Letters journal, physicists led by
> Tilmann Maerk of Austria's University of Innsbruck describe
> experiments on the effects of low-power radiation on chemicals found
> in RNA, the "helper" molecules that cells use to carry out genetic
> instructions.
>
> Using a beam of radiation lower in energy than that used in any
> previously reported experiments - about 1,000 times weaker than the
> dangerous ultra-violet radiation in sunlight and far lower than the
> level at which damage was thought to occur in cells - the team
> discovered fragmentation in the RNA parts. Not strong enough to
> electrify the molecules, the beam instead triggered secondary effects
> that splintered the molecules in a quick chain reaction. Maerk called
> the damage "a big surprise."
>
> The research team told Physics News Update, an Internet publication
> of the American Institute of Physics, that the same low-energy beam
> disrupts a constituent molecule of DNA, the repository of genes in
> cells.
>
> "This work challenges current models of how ionizing radiation
> damages cellular material and thus how (the cell) might be treated,"
> says biological physics expert Nigel Mason of London's Open
> University. The chain reaction may target particular sites in cells
> for destruction, he says, suggesting a way of using low-energy
> radiation to kill tumor cells. Doctors already use high-energy
> radiation to kill tumors, but a low-energy dose would not have the
> same harmful side effects.
>
> "The standard view in radiation biology is that most, although not
> all, effects of consequence for human health are produced by ionizing
> radiation," making the finding particularly surprising, says health
> physicist Marco Zaider of Memorial Sloan-Kettering Cancer Center.
>
> Zaider notes the radiation from cell phones and computer screens is
> much lower energy than the radiation described in the report.
>
> The next step is to work with the molecules in water solutions to
> better mimic behavior in cells.
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