[ RadSafe ] BEIR VII Report

[John Jacobus]

Dr. Scott,
Thanks for the comments. Even though my work is based
in health physics and dealing with the public, I try
and keep a focus on the practical aspects of research.
 While I think that it is clear that radiation, and
maybe other agents, appear to provide some protection,
that is not what the public hears.  Generally, I have
to deal with the questions such as: "I had a CT scan. 
Will I get cancer?" 

Your comments on the purposes of the BEIR VII report
are illuminating.  (I am still trying to slog through
the report.)  Also, thanks for the information on your
studies. I will keep an eye out for it.


--- "Scott, Bobby" <BScott at lrri.org> wrote:

> On 7/2/05, John Jacobus wrote:
> 
> "Maybe I not looking at this issue as you are.  I
> really do not consider the LNT to be the issue in
> developing safey regulations..."
> 
> Reply from B.R. Scott:
> Thanks John for sharing your views on this topic. In
> section 13 of the
> BEIR VII prepublication draft, it is stated that the
> primary task of the
> BEIR VII committee was "to develop the best possible
> risk estimate for
> exposure to low-dose, low-LET radiation in human
> subjects."  Thus,
> developing safety regulations was not the primary
> focus.  My view is
> that the "best possible risk estimate" cannot be
> obtained solely based
> on epidemiological studies.  One has to first have a
> basic understanding
> of the underlying stochastic biological effects
> associated with
> low-dose, low-LET radiation induced cancer. These
> stochastic effects
> include induced mutations, neoplastic
> transformation, and apoptosis.
> Fortunately, ongoing basic research around the world
> is focusing on
> low-dose-induced stochastic radiobiological effects
> and results obtained
> have led to nonlinear dose-response relationships
> more as a rule then an
> exception.  The new journal, Nonlinearity in
> Biology, Toxicology and
> Medicine features a number of publications of
> nonlinear dose-response
> relationships for low-dose, radiation-induced
> stochastic biological
> effects.
> 
> Note that the stated primary task of the BEIR VII
> committee was not to
> determine if a risk of radiation-induced harm
> actually exists after low
> doses of low-LET radiation.  Implied in the stated
> primary task was the
> assumption that elevated cancer risk always exists
> (after any
> irradiation) and their task is to quantify the
> assumed elevated risk.
> Research results obtained by my research group
> indicate that for persons
> already bearing precancerous cells (e.g. heavy,
> long-time smokers), low
> doses (or low dose rates) of low-LET radiation could
> activate a
> protective process that selectively eliminates
> precancerous cells
> thereby reducing the risk of cancer.  The selective
> cell killing is via
> apoptosis and has been named the "protective
> apoptosis mediated (PAM)
> process".  Animal studies have shown that low doses
> of low-LET radiation
> can extend the cancer latent period for spontaneous
> cancers. Both
> epidemiological and animal studies have shown that
> protracted exposure
> to low-LET radiation can reduce the cancer incidence
> below the
> spontaneous level.  Our in-press paper (Nonlinearity
> in Biology,
> Toxicology and Medicine) shows evidence for low-dose
> rate gamma
> radiation suppressing lung cancer induction in Mayak
> workers by alpha
> irradiation (from inhaled Pu-239).  Some of the
> indicated data are
> discussed in the Low Dose Research section of my
> webpage:
> http://www.radiation-scott.org.  See for example the
> subsection on
> "Stochastic Thresholds and Nonlinearity" (plenary
> session presentation
> at the BELLE 2005 Conference).
> 
> Bobby R. Scott
> Lovelace Respiratory Research Institute


+++++++++++++++++++
"Every now and then a man's mind is stretched by a new idea and never shrinks back to its original proportion." -- Oliver Wendell Holmes, Jr.

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com


		
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