[ RadSafe ] DOE workshop presentation

Ludwig E. Feinendegen feinendegen at gmx.net
Tue May 17 01:55:31 CDT 2011

Dear Bobby:  Again, thanks for the lecture.  I am glad that OBER seems to be safe - after all the uncertainties. Best, Ludwig

----- Original Message ----- 
From: "Scott, Bobby" <BScott at lrri.org>
To: <radsafe at health.phys.iit.edu>
Sent: Tuesday, May 17, 2011 12:58 AM
Subject: [ RadSafe ] DOE workshop presentation

> Hi All:
> In case it may be of interest, my presentation given last week at the
> DOE Low Dose Radiation Research Program Investigators' Workshop X is
> available at the link below:
> "Differential epigenetic changes in the lung after low and high
> carcinogen doses and implications for designing molecular epidemiology
> and other studies of radiation-induced lung cancer"
> http://dspace.lrri.org:8080/xmlui/handle/123456789/1064
> In the presentation, I point out the need for new terminology related to
> discussing consequences to humans from low-level exposure to low- or
> low- plus high-LET radiation (e.g., radiation exposure in the home from
> radon progeny).  I introduce the adaptive protection function, A(x), and
> benefit function B(x) = 1 - exp[-A(x)], which respectively correspond to
> the high-dose hazard function H(x) and related risk function R(x) = 1-
> exp[-H(x)], widely used in risk assessment. B(x) is the probability of
> radiation activated natural protection (ANP) against cancer (e.g.,
> against smoking-related lung cancer). The independent variable x is the
> dose or exposure level.  Interestingly, for low-level exposure to radon
> progeny and for lung cancer, the benefit B(x) can be close to 1 (e.g.,
> for protecting against smoking-related lung cancer) while the risk R(x)
> for radiogenic cancer is close to zero.  This indicates that the
> probability B(x) can be orders of magnitude greater than the probability
> R(x), while much of the current focus is unfortunately on R(x) (usually
> under the invalid LNT hypothesis). At the EPA's action level of 4
> picocuries/L (approximately 150 Bq/cubic meter), B(x) = 1 for ANP
> against sporadic lung cancer (i.e., everyone expected to benefit from
> natural protection against lung cancer). The natural protection when
> maintained over a prolonged period prevents a future cancer with
> probability PROFAC (the protection factor, a population average which
> varies with different populations). PROFAC is the average over the
> at-risk population of individual-specific protection factors "profac".
> For x close to zero, cancer relative risk (RR; population average) is
> given by RR = 1 - B(x)PROFAC (hormetic zone where RR < 1). For large
> values of x, B(x) goes to zero (no benefit) and H(x) can be >> 1
> (serious hazard with R(x) close to 1).
> Bobby R. Scott
> Senior Scientist
> Lovelace Respiratory Research Institute
> 2425 Ridgecrest Drive SE
> Albuquerque, NM 87108 USA
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