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Post Info TOPIC: The LNT Hypothesis May Have Outlived Its Usefulness
10kBq Jaro


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The LNT Hypothesis May Have Outlived Its Usefulness
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Seminar Presented by: Bobby R. Scott, Ph.D.


Affiliation: Lovelace Respiratory Research Institute


Title: The LNT Hypothesis May Have Outlived Its Usefulness


Seminar Location: Los Alamos National Laboratory, Health, Safety, and Radiation Protection Division


Seminar Date: November 10, 2005


http://www.radiation-scott.org/Los_Alamos_Seminar_Nov_05_B_Web_ver.pdf


Abstract:


"The linear no-threshold (LNT) radiation risk model has been used in radiation protection standards for over 50 years. Yet there is significant debate among scientists whether this model is appropriate for protecting people at low doses and dose rates of radiation. Based mainly on cancer data from the essentially instantaneous radiation exposures from nuclear blasts in Hiroshima and Nagasaki, the National Academy of Sciences BEIR VII Report concluded that the available data for low linear-energy-transfer (LET) radiation were consistent with the LNT hypothesis. Accordingly, risk is constrained to be elevated for any amount of radiation, even for background radiation, whose dose rates are more than 10 orders of magnitude less than for the A bombs survivors.


Thus, BEIR VII concluded that background radiation is harmful, even though there is no evidence for such harm. The Committee Chair went so far as to suggest that persons residing at high altitudes (e.g. such as persons residing in Los Alamos), may want to move to a lower altitude to reduce their level of cosmic-ray exposure.


This presentation will focus on reasons for abandoning the use of LNT for low-dose, low dose-rate risk assessment. Results will be presented supporting the view that low doses and dose rates of low-LET radiation (or low- plus high-LET radiation) protect us from cancer and possibly other diseases. Three protective processes are now recognized as being induced by low-LET radiation: 1) induced high fidelity DNA repair/apoptosis; 2) a novel protective apoptosis-mediated process, which selectively removes genomically compromised cells; and (3) immune system stimulation. These mechanisms are incorporated into a novel hormetic relative risk model that accounts for these protective processes.


A news media report describing BEIR VII as a "trillion dollar mistake" is on target. Further, LNT will aid terrorists in the case of a dirty-bomb incident. Radiation-phobia related casualties are far more likely following a dirty-bomb incident than are casualties directly related to radiation exposure. As a point of reference, more than 100,000 radiation-phobia-associated abortions were reported to have occurred in Western Europe just after the Chernobyl accident, a tragic loss of life."



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stungun


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Hey Jaro,


    This is the same Dr Bobby Scott that I quoted in the anti-pu-238 production testimony I shared with y'all! He is an interesting guy I have corresponded with.


   It was his DOE worker dosimetry paper I quote, that says pu-238 is so radioactive, workers who have inhaled ANY pu-238 should be considered to have exceeded their annual limit of 5 rem (5,000 mrem)...


   But please note, Dr Scott does not ever claim any hormesis benefits from exposure to alpha emitters, like plutonium-238, for Space Batteries. His hormesis claims are only for low gamma exposure and adults. Nor does he claim that hormesis is true for pregnant women and children. These are the issues that must be considered for nuclear production downwinders, since pregnant women and children are always present downwind. We need a Space Program, and a National Energy Plan that understands Motherhood, and the importance of protecting the most fragile future generations...



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Dr. Peter Rickards DPM
10kBq Jaro


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stungun wrote:

It was his DOE worker dosimetry paper I quote, that says pu-238 is so radioactive, workers who have inhaled ANY pu-238 should be considered to have exceeded their annual limit of 5 rem (5,000 mrem)...

Trust me: we have ALL inhaled Pu-238 from weapons testing fallout.


But I don't see us getting anywhere near 5 rem from a few atoms (which qualifies as "ANY pu-238").... show me the calculation.



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stungun


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Ahh Jaro,


   As Ron Reagen would say, "There you go again..."


We have covered this, but you were probably just knee jerk reacting to my posts, and didn't actually read or think about the references before criticizing them.


   First, the pu-238 particles, that DOE admit leak through the HEPA filters, contain thousands of atoms, not the "few atoms" that you pooh-pooh. The 0.3 micron size is what the DOE admits can escape at a rate of 3 particles per ten thousand, or as DOE says, a 99.97% efficiency.


    Lot's more pu-238 whispers out than that, but do the math from density for the number of atoms. I like to refer to them as perpetual points of radiation when inhaled.


   Second, this is not weapons grade pu-239 you pooh-pooh. The space battery is pu-238, which is 275 times more ravaging to lung and body DNA than inhaling weapons pu, which ain't exactly recommended either.


   So here is the repost of part of my official scoping hearing comments...


 

 


"Thus, rather than addressing questions such as 'Did the calculated worker's intake of (PuO2)-Pu-238 exceed the ALI?', it is better to address questions such as 'What is the probability that (PuO2)-Pu-238 intake by a given worker occurred and exceeded the ALI?'"






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Variability in PuO2 intake by inhalation: Implications for worker protection at the US Department of Energy
Scott BR, Fencl AF
RADIATION PROTECTION DOSIMETRY

83 (3): 221-232 1999






Document type: Article   
Language: English   
   
       
Abstract:
This paper describes the stochastic exposure (SE) paradigm where, at most, small numbers of airborne toxic particles are presented for inhalation. The focus is on alpha-emitting plutonium dioxide (PuO2) particles that may be inhaled by Department of Energy (DOE) workers. Consideration of the SE paradigm is important because intake of only a few highly radioactive PuO2 particles, such as (PuO2)-Pu-238, could greatly exceed the annual limit on intake (ALT) used to control worker exposure. For the SE paradigm, credible intake distributions evaluated over the population at risk are needed, rather than unreliable point estimates of intake. Credible distributions of radiation doses and health risks are also needed. Because there are limited data on humans who inhaled PuO2, these distributions must be calculated. Calculated distributions are presented that relate to the intake of radioactivity via inhaling polydisperse PuO2 particles. The results indicate that a large variability in radioactivity intake is expected when relatively small numbers of PuO2 particles are inhaled, For the SE paradigm, one cannot know how many PuO2 particles were inhaled by an individual involved in a given inhalation exposure scenario.   Mathematical tools for addressing the latter question are presented, and examples of their applications are provided, with emphasis on possible DOE worker exposures at the Rocky Flats facility near Denver, Colorado. The alpha-emitting isotopes Pu-238, Pu-239, Pu-240, and Pu-242 are found at Rocky Flats. Although Pu-238 is thought to be present in relatively small amounts there, intake via inhalation of only a few (PuO2)-Pu-238 particles could greatly exceed the ALI.



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Dr. Peter Rickards DPM
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