[ RadSafe ] Calculated Health Impacts of Reducing NaturalBackground Ionizing Radiation

Muckerheide, James jimm at WPI.EDU
Thu Apr 6 19:30:10 CDT 2006

Hi Bobby,

Good discussion. One thought is that the damage to biological processes from
suppressing background radiation would compete with the "opportunity" to get
cancer and other diseases.  

Also, it is possible to reduce background to near zero.  In addition to
shielding and "clean room" conditions for removing radon decay products,
etc., food needs to use potassium with the K40 removed.  The calutrons at Oak
Ridge stripped K-40 and K-41 from the primary K-39.  Don Luckey wanted to use
the offspring of animals that had no K-40, but even in feeding animals K-39,
the potassium turnover in the body will remove most of it in a few weeks.

Regards, Jim 

> -----Original Message-----
> From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of
> Scott, Bobby
> Sent: Thursday, April 06, 2006 6:47 PM
> To: radsafe at radlab.nl
> Subject: [ RadSafe ] Calculated Health Impacts of Reducing
> Ionizing Radiation
> Related to writing a chapter entitled "Radiation Hormesis and the
> Control of Genomic Instability" for a Nova Science Publishers, Inc. book
> with the tentative title "New Research on Genomic Instability," I now
> have some new modeling results that led to the following conclusions:
> 1.  Reducing current natural background ionizing radiation to near zero
> would be expected to lead to significant increases in cancer and other
> genomic instability associated diseases as well as increased mortality
> from these diseases.
> 2. A significant reduction in life expectancy would therefore be
> expected to be associated with reducing natural background ionizing
> radiation to near zero.
> I recognize that it may not be possible to reduce natural background
> ionizing radiation to near zero; however, carrying out calculations of
> the expected health consequences can be quite informative, especially in
> light of the widely circulated claims by some (largely in the US) that
> any amount of ionizing radiation is harmful (linear, no-threshold [LNT]
> hypothesis).
> Our modeling research shows that at current natural background radiation
> levels and at lower levels, the risk of radiation-induced cancer should
> be governed by the degree to which a system of protective biological
> processes (normal DNA repair/apoptosis, presumed related to the p53
> protein; an auxiliary apoptosis process that selectively removes
> genomically unstable cells and is presumed to be independent of p53; and
> immune system stimulation) is activated. This system of transient
> protection against harm is activated by low doses of low-LET radiation
> including natural background low-LET radiation.  Dose somewhat above
> natural background radiation also activate the protection.  We call this
> form of low-stress activated protection "adapted protection."  Our
> dose-response models for low-dose radiation-induced stochastic
> biological effects are called "adapted protection models".  Adapted
> protection is a form of hormesis, thus our models are also called
> hormetic models.
> Natural background radiation doses above a stochastic threshold (which
> varies for different individuals) probably over and over activates the
> indicated system of protection, which is transient.  Background low-LET
> radiation (including gamma rays associated with radon progeny) doses
> accumulated over a few weeks may be sufficient for activating the
> transient protection.  High-LET alpha radiation by itself appears not to
> activate the protection, based on limited data for neoplastic
> transformation. Each of us likely has a different threshold for
> activating the indicated protection.  Below the minimum threshold, no
> protection from the indicated system is expected in anyone.  Low
> fidelity DNA repair which is error-prone may operate below the threshold
> but it is also possible that no repair would occur.  Above the maximum
> threshold, each of us are expected to have the system of protection
> activated, but not if the doses are too high where a second stochastic
> threshold comes into play and inhibits a significant amount of
> protection.  This second threshold however appears to be quite large in
> comparison to natural background radiation and probably depends on dose
> rate (increasing as dose rate is reduced). These stochastic thresholds,
> guarantee nonlinear dose-response curves for radiation-induced effects
> such as mutations, neoplastic transformation, and cancer.
> According to the LNT hypothesis, reducing a natural background radiation
> (low- plus high-LET) dose of 0.05 mSv to 0.0000000005 mSv (eight-fold
> lower) would be expected to reduce the risk of cancer by a factor of
> 100,000,000. In contrast our adapted protection modeling results
> indicated that such a dose reduction would be expected to lead to the
> loss of low-dose-radiation (low-LET component) induced adapted
> protection leading any where from a modest to an astronomical increase
> in cancers and other genomic instability associated diseases.  New
> funded research is needed to reduce the indicated uncertainty.
> The adapted protection indicated when activated by low-level, low-LET
> radiation can reduce the cancer incidence to far below the spontaneous
> level.  Many epidemiological and ecological studies have shown this.
> Unfortunately, poorly designed epidemiological studies of nuclear
> workers have apparently misinterpreted adapted protection to be a
> healthy worker effect.  Such studies should be designed to allow
> distinguishing between the healthy worker effect and adapted protection.
> Funding agencies should insist on this for future nuclear-worker-based
> studies that they fund.
> In closing, our modeling results should bring pause to those who have in
> the past not hesitated to make dire predictions of large numbers of
> cancer deaths after low-level radiation exposures of large populations
> based on the LNT hypothesis.  I thought that readers of the Radsafe
> Digest would like to know about our new findings.  The calculations are
> rather complicated and therefore are not presented here but are included
> in the indicated chapter.  I will submit an e-mail to the digest when
> the chapter is published for those who may have interest in reading it.
> Sincerely,
> Bobby R. Scott
> Senior Scientist
> Lovelace Respiratory Research Institute
> 2425 Ridgecrest Drive SE
> Albuquerque, NM 87108 USA
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