The Oxygen Effect as an Ignored variable in Mammalian Dose Response.

Small mammals
“……small doses of radiation produces premature ageing…Animals in hiberation are remarkably resistant, and doses of many thousands of roentgens are necessary to kill marmots or squirrels while they are dormant. On warming, the animals will behave as if they had been irradiated in the non-hibernating state.

The bat appeared to be the one remarkable exception amongst mammals in that the lethal dose observed was of the order of 15,000 r, i.e. it was twenty to fifty times more resistant than other mammals. …these bats did not eat in captivity and this lowered their metabolic rate equivalent to that of hibernation and was responsible for the apparent radiation resistance. Bats which were eating succumbed at 700 r.” Alexander, Peter, “Atomic Radiation and Life”, Pelican Books, 1957, Chester Beatty Research Institute, Institute of Cancer Research, Royal Cancer Hospital, London, England.

Humans

Hiroshima doctors told Hersey:
“Those who had lain quietly for days or even hours after the bombing were much less
liable to get sick than those who had been active.”
Hersey, “Hiroshima”, 1946, First Vintage Books Edition, February 1989,
ISBN 0-679-72103-7, pp 78.


The Oxygen Effect

“A suggestion made as long ago as 1929 by Risse, one of the earlietst workers in the field, has now been confirmed; on irradiation, water is split up into free radicals: H20 ………..> H- + H0- These, it will be remembered (see page 19), are highly reactive entities since they do not have the electron configuration required for stable molecules.” Alexander explains the process of electron number change needed to achieve stability. He continues: ” The great reactivity of activated water is due to these radicals, which attack most organic substances so as to attain a normal electron configuration.” “Atomic Radiation and Life”, Chapter 8, on pages 183 and 184, Peter Alexander, Penguin Books, 1957. Chester Beaty Research Institute, Institute of Cancer Research: Royal Chester Hospital, London, S.W.3. Chapter 8 “Enter the Chemist”.

The complexity of the possible chemical results of any given ionisation of the cell’s contents renders any specific outcome a matter of circumstance. At the level of the organism, invoking a “relaxation response” after exposure (and probably prior to exposure) seems, on the basis of the evidence reported by Hersey in 1946, to makes sense. The explanation, as discussed by Alexander in 1957, lies within the realm of the oxygen effect.

Good nutrition is important and solutions may seem to be counter-intuitive. An important fact is the role played by oxidant chemicals normally produced in humans as a means by which the body defends itself against ionising radiation.
See http://en.wikipedia.org/wiki/Nitric_oxide NO may have a protective effect via a long known chemical interaction in regard to H and O radical damage of cells.

The following paper by Dr. Louis de Saint-Georges discusses the many possible outcomes from exposoure to ionising radiation. The paper includes a discussion on the difficulties posed by both Radiation Hormesis and Adaptive Response
in this respect: https://docs.google.com/viewer?a=v&q=cache:-NTWPB3vyvQJ:www.radiationhormesis.com/RadiationHormesis/Low-dose%2520ionizing%2520radiation%2520exposure.pdf+Dr.+Louis+de+Saint-Georges+radiation+homeostasis&hl=en&gl=au&pid=bl&srcid=ADGEEShnZ5p503Z_o1FLL15wMEbWkjvTrG0kp7CXXPUYWfIHURp8ICdiE6Rvhu_aiHlJ-WvvqnwoO88AEmzqpp6YQTzSAvmWXWlyWgI936BkDSxSknH7WkHEn8D9-60bOLPpqZmm78PR&sig=AHIEtbRy3943mOgEwCQlyxCs9k4bXv8hIw

The paper is entitled “Low-Dose Ionizing Radiation Exposure: Understanding the risk for Cellular Transformation”. The abstract states: “L.DE SAINT-GEORGES
SCK•CEN, Department of Radiobiology, Mol, Belgium
ABSTRACT:Radiation is energy transfer.When radiation has sufficient energy to remove an orbital electron from its
atom, an ionized atom is formed, and radiation with the capacity to do this is called ionizing radiation.The primary
effect of radiation is the induction of free radicals and Reactive Oxygen Species (ROS). All the molecules in every cell
of the body are potential targets,but the final effect of radiation will be mainly of concern if the molecule impaired is a molecule critical for life. ROS are also generated as a result of the aerobic respiration (metabolic ROS) in much larger
quantity than from the natural radiation background. During evolution, life has developed powerful control and repair
mechanisms that greatly contribute to minimize the risks associated with the generation of free radicals and ROS. At
low irradiation doses the probability of the risk is therefore proportional to the dose, and the ALARA (As Low As
Reasonable Achievable) principle seems to be a valuable goal in radioprotection policies. (JBiol Regul Homeost
Agents 2004;18:96-100)

A section deals with Radiation Hormesis and Adaptive Response: “Adaptive response and hormesis are often
mentioned to minimize the risk of radiation or sometimes to deny any adverse outcome below a dose threshold, as detailed below.

Hormesis is a hypothesis that emphasises the possible beneficial effect of low doses of radiation and claims the necessity of a low-dose exposition to get some benefits while excluding any risk.

However, this concept is controversial. According to the hormesis
model, people should be exposed to low radiation dose unless it is demonstrated with certitude that there is no benefit from such exposure.The possibility of adverse effects is not even considered.

We may wonder why the proponents of the hormesis model acknowledge a radiation threshold value for harmful effects, but reject it for beneficial effects.Considering the essentially random interaction between radiation and target molecules leading to unpredictable molecular damage, it appears surprising that at low doses only beneficial effects would occur while noxious effect would require a dose above a certain threshold.

To consider hormesis as an argument against actual dose limits would only be valid if the efficacy of hormesis could be demonstrated for the effects against which one wants to protect at low radiation doses, i.e. cancer and genetic
damages.

Unfortunately this is not yet demonstrated in an unequivocal way.Therefore, the hormesis model is currently not considered in radioprotection.

The theory of “adaptive response”, (not to be confused with hormesis) shows that a low dose can reduce the effect of a higher dose when administered after a short time delay. This theory is based on substantial evidence. To reduce a risk appears beneficial, but it does not mean that the risk is eliminated. According to the “adaptive response” model, a first low dose (conditioning dose) is considered to stimulate the DNA repair mechanisms that contribute to reduce the effect of a subsequent higher dose. But the initial low dose can only stimulate the limited number of cells actually hit, the total of which in function with the dose. This situation never excludes the possibility of a transformation of one of the cells.

The next higher dose concerns all cells. Some of them having the repair mechanisms stimulated by the first conditioning dose, and may repair the damage more easily. The other cells, that were not previously hit, are not protected. The total
damage can be reduced by a factor depending on the number of the cells conditioned but will always be dependent on the total number of the cells exposed to both doses.

Would the conditioning of all cells solve the question? No, because to reach such a goal we have to increase the conditioning dose and the risk remains proportional to the dose and to the number of cells irradiated.

Therefore the adaptive response does not appear to be a relevant mechanism for radiation protection because the (low) conditioning dose that defines it, also generates a risk of transformation. On the other hand the challenging dose is not a low dose.

We suggest that natural background irradiation and metabolic ROS are already stimulating toward some adaptive response by a constant stimulation of the repair mechanisms. Then it would appear that there is no need to add to this radiation burden.

Evolution, in our natural radioactive environment, is often used as an argument to support such beneficial effects of low-dose radiation. We should remember that if Evolution has led to the current scala of successfully living species, the eliminated species are unavailable to analyse the non-beneficial aspect of evolution.” end quote.

All things considered, solar is simpler and sustainable. Such alternatives do not require the invention of some fictious moral justification such as “Evolution demands we give you a dose of Hot Particles, they are like vitamins.”

2 Responses to “The Oxygen Effect as an Ignored variable in Mammalian Dose Response.”

  1. Reference lists for exposing radiation hormesis and quack radiation “science” « nuclear-news Says:

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  2. Reference list on ‘radiation hormesis’ and ‘adaptive radiation’ « nuclear-news.info Says:

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