AW: [ RadSafe ] Danger of ADJACENT HIGH-Dose Radiation
John Jacobus
crispy_bird at yahoo.com
Mon Sep 1 21:26:47 CDT 2008
Rainer,
I am puzzled why you would even mentioned hormesis when commenting on this article. It appears to me that the "magic" of hormesis is slowly dissipating as better and better science shows what biological responses lead to the observed low dose effects.
Hormesis has always lacked a relevancy to real life. Tell me how it would be applied to the radiation workers? To members of the public? As you note, this experiment is irrelevant to low dose radiation issues, but so is hormesis.
+++++++++++++++++++
It is also a good rule not to put overmuch confidence in the observational results that are put forward until they are confirmed by theory.
Arthur Eddington
-- John
John Jacobus, MS
Certified Health Physicist
e-mail: crispy_bird at yahoo.com
--- On Mon, 8/25/08, Rainer.Facius at dlr.de <Rainer.Facius at dlr.de> wrote:
From: Rainer.Facius at dlr.de <Rainer.Facius at dlr.de>
Subject: AW: [ RadSafe ] Danger of ADJACENT HIGH-Dose Radiation
To: crispy_bird at yahoo.com, radsafe at radlab.nl
Date: Monday, August 25, 2008, 5:02 AM
Dear John,
the article by Mancuso et al. (2008) has been discussed here with respect to
its improper use of the term "bystander effect" instead of the proper
and long established term "abscopal effect" and with respect to the
dose the cerebellum of the shielded mice did receive due to finite attenuation
of the shields and due to backscattering from the body of the mice. Furthermore
it was pointed out that the findings from this experiment are irrelevant
regarding low dose radiation protection issues.
To my knowledge, in this discussion the term hormesis has not been mentioned at
all but once by myself. I drew attention to the fact (fig. 2D and fig. S1 of the
supplement) that the data by Mancuso et al. exhibit the lowest (in fact zero)
incidence of medulloblastoma not for the un- or sham irradiated animals but for
those unshielded animals which were exposed to a uniform whole body dose of 36
mGy, i.e., that dose which the cerebellum of the partially shielded mice
received from stray radiation.
I agree that - in my view - Howard Long occasionally is straining the evidence
in favour of hormesis - just as you are trying to ignore or depreciate it. This
time however I am the one who is guilty of introducing the incriminated word -
though I mentioned it only casually at the very fringe of the discussion.
Best regards, Rainer
Dr. Rainer Facius
German Aerospace Center
Institute of Aerospace Medicine
Linder Hoehe
51147 Koeln
GERMANY
Voice: +49 2203 601 3147 or 3150
FAX: +49 2203 61970
-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag
von John Jacobus
Gesendet: Sonntag, 24. August 2008 23:43
An: radsafe at radlab.nl
Betreff: RE: [ RadSafe ] Danger of ADJACENT HIGH-Dose Radiation
I wonder how many others on this list have read the article. I am sure Dr.
Long has not. I would be nice to see a discussion of the study as opposed to a
summary dismissal as it may go against the belief in hormesis. Is that too
much to ask for?
+++++++++++++++++++
"Part of human nature resents change, loves equilibrium, while another
part welcomes novelty, loves the excitement of disequilibrium. There is no
formula for the resolution of this tug-of-war, but it is obvious that absolute
surrender to either of them invites disaster."
-J. Bartlet Brebner
-- John
John Jacobus, MS
Certified Health Physicist
e-mail: crispy_bird at yahoo.com
--- On Thu, 8/21/08, Cary Renquist <cary.renquist at ezag.com> wrote:
From: Cary Renquist <cary.renquist at ezag.com>
Subject: RE: [ RadSafe ] Danger of ADJACENT HIGH-Dose Radiation
To: "NIXON, Grant" <Grant.NIXON at mdsinc.com>, radsafe at radlab.nl
Date: Thursday, August 21, 2008, 1:16 PM
The distances involved in this experiment seem too far for diffusion of
radicals.
What I understand (grok [for the geeks out there]) from the few papers that I
have read...
Acute "low-level" exposures seem garner signal transduction responses
that favor cell death or very basic repair attempts. Acute
"high-level"
exposures seem to result in signal transduction responses that favor
(emergency) repair mechanisms.
In this experiment, it seems that the (emergency) repair mechanisms are being
triggered in the shielded area -- the repairs are either acting on damage caused
by the low-level scatter or the normal damage caused by cellular processes.
I see that normal wild-type mice in the experiment did not display any
carcinogenic response -- only the patch1 mice. Normal mice did show short term
effects that seemed to be evidence for the transmission of the high-exposure
response to the shielded areas.
C.
---
Cary Renquist
RSO, Eckert & Ziegler Isotope Products
Office: +1 661-309-1033
cary.renquist at ezag.com
-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of
NIXON, Grant
Sent: Wednesday, 20 August, 2008 13:09
To: HOWARD.LONG at comcast.net; ROY HERREN; radsafe at radlab.nl
Subject: RE: [ RadSafe ] Danger of ADJACENT HIGH-Dose Radiation
To add to Howard's comment:
Perhaps the mechanism for the DNA damage to adjoining tissue (the so-called
"bystander effect") is nothing more than a propagated free-radical
reaction having nothing to do with cell-to-cell communication. The high doses
would liberate such large numbers of free-radicals that the affected perimeter
of affected tissues would increase on physical grounds alone (diffusion theory
coupled with target theory). The "chemical that blocks cell-to-cell
communication" may simply be a free-radical scavenger.
Grant I. Nixon, Ph.D., P.Phys.
Science Specialist (Dosimetry/Physics/Engineering) BEST Theratronics
413 March Road
Ottawa, ON K2K 0E9
Canada
tel. (613) 591-2100 x2869
fax. (613) 591-2250
-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of
HOWARD.LONG at comcast.net
Sent: Wednesday, August 20, 2008 12:36 PM
To: ROY HERREN; radsafe at radlab.nl
Subject: [ RadSafe ] Danger of ADJACENT HIGH-Dose Radiation
So, "high dose radiation - 12,000 times - chest x-ray" affects
adjacent tissue?
Would other severe injury, like crushed arm, affect the rest of the body? Of
course!
Why the surprise?
Why the false headline that it "Hints at Dangers of Low Dose
Radiation"?
Hormesis, low dose good where high dose bad, must be taught.
We must correct this disinformation by fearmongers to dismantle over-regulation
and liberate nuclear power.
Howard Long
-------------- Original message --------------
From: ROY HERREN <royherren2005 at yahoo.com>
> http://sciencenow.sciencemag.org/cgi/content/full/2008/818/3
>
> Bystander Effect" Hints at Dangers of Low-Dose Radiation
>
> By Jocelyn Kaiser
> ScienceNOW Daily News
> 18 August 2008That lead apron you wear during a dental x-ray is
supposed to
> protect the rest of you from radiation. But it may not work very well,
according
> to a new study. When cancer-prone mice were placed in lead containers
and
> irradiated on just the lower half of their bodies, they developed
brain tumors.
> The results suggest that radiation could be riskier than scientists
thought.
> The study builds on a surprising effect, first observed 16 years ago.
When cells
> in culture are exposed to ionizing radiation, even those not directly
hit
> sustain damage to chromosomes. Apparently, the irradiated cells pass
on a
> distress signal or emit some chemical that breaks the DNA of
neighboring cells
> (ScienceNOW, 7 September 2005). Although this "bystander effect"
has
been
> observed in tissue culture and recently in living animals, no
experiments have
> yet linked it to the main reason for concern: Bystander effects might
trigger
> cancer. Some scientists even suspect the opposite--that the bystander
responses
> could protect against the disease by killing damaged cells.
> Now it seems that the cancer risk is real. Radiation oncologist Anna
Saran at
> the Italian National Agency for New Technologies, Energy and the
Environment in
> Rome and colleagues studied mice with a mutation in a gene called
Patched that
> makes them susceptible to brain tumors early in life. They placed
newborn mice
> in lead shields that protected their heads and upper bodies, then
zapped them
> with high-dose x-rays, or about 12,000 times the dose of a dental or
chest
> x-ray. The scientists found that the cerebellums of these animals had
higher
> than normal amounts of DNA damage and apoptosis, or programmed cell
death. By 40
> weeks of age, 39% of the shielded mice had developed brain tumors.
That's a lot
> considering that the rate was 62% in Patched mice that were irradiated
all over,
> including their heads. Patched mice that weren't irradiated did not
develop
> brain cancer.
> When the team injected the shielded mice with a chemical that blocks
> cell-to-cell communication before irradiating them, they detected no
DNA breaks
> and the amount of apoptosis decreased more than threefold. Even though
the
> irradiated tissues are far away from the brain, they are connected by
neurons
> that could be passing on bystander signals, Saran says. The results
appear
> online this week in the Proceedings of the National Academy of
Sciences.
> "This is a milestone paper," says Columbia University radiation
physicist David
> Brenner. He suggests that current estimates of cancer risk from low
doses of
> radiation--say, from naturally occurring radon and diagnostic
tests--may
> underestimate the danger by failing to take into account bystander
effects. To
> learn more, however, the mouse work should be repeated with lower
doses of
> radiation, Saran says.
>
>
>
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and
understood the
> RadSafe rules. These can be found at:
http://radlab.nl/radsafe/radsaferules.html
>
> For information on how to subscribe or unsubscribe and other settings
visit:
> http://radlab.nl/radsafe/
_______________________________________________
You are currently subscribed to the RadSafe mailing list
Before posting a message to RadSafe be sure to have read and understood the
RadSafe rules. These can be found at:
http://radlab.nl/radsafe/radsaferules.html
For information on how to subscribe or unsubscribe and other settings
visit: http://radlab.nl/radsafe/
_______________________________________________
You are currently subscribed to the RadSafe mailing list
Before posting a message to RadSafe be sure to have read and understood the
RadSafe rules. These can be found at:
http://radlab.nl/radsafe/radsaferules.html
For information on how to subscribe or unsubscribe and other settings
visit: http://radlab.nl/radsafe/
_______________________________________________
You are currently subscribed to the RadSafe mailing list
Before posting a message to RadSafe be sure to have read and understood the
RadSafe rules. These can be found at: http://radlab.nl/radsafe/radsaferules.html
For information on how to subscribe or unsubscribe and other settings visit:
http://radlab.nl/radsafe/
_______________________________________________
You are currently subscribed to the RadSafe mailing list
Before posting a message to RadSafe be sure to have read and understood the
RadSafe rules. These can be found at: http://radlab.nl/radsafe/radsaferules.html
For information on how to subscribe or unsubscribe and other settings visit:
http://radlab.nl/radsafe/
More information about the RadSafe
mailing list