[ RadSafe ] Biologic Response to Ionizing Radiation

[Howard]

Chris,
 Indeed, "Higher forms of life are not possible without vigorous and efficient
DNA repair mechanisms". 
Feinendigan and Pollycove presented studies showing something like 10 exponent biologic repair response (hormesis) in irradiated mice, something akin to immunization with viral vaccines (think smallpox) or allergy shots. 
I hope they will comment. 
Howard Long

On May 9, 2011, at 3:13 AM, Doug Huffman <doug.huffman at wildblue.net> wrote:

> Well said!  Thank you.  Tersely too.
> 
> On 5/9/2011 02:32, Chris Hofmeyr wrote:
>> Hi, Bill,
>> 
>> Being alive of course incurs a 100% integrated risk irrespective of the meaning
>> of safety!. However, the LNT crowd treats living organisms as dead matter, i.e.
>> with no biological response to (radiation) damage. That is most probably a poor
>> assumption. Higher forms of life are not possible without vigorous and efficient
>> DNA repair mechanisms. Aging probably results from the fact that the repair
>> mechanisms are not quite 100% effective to begin with and weaken with time.
>> Regards,
>> Chris
>> chris.hofmeyr at webmail.co.za
>> 
>> On Fri, 6 May 2011 13:42:16 -0400 "Bill Prestwich" <prestwic at mcmaster.ca> wrote
>> 
>>> Hi John,
>>> 
>>> This is a longer thing I sent regarding a local discussion here at Mac
>>> arising from the 86 billion radsafe posting.
>>> 
>>> I don't think the radsafe posting was meant to be a rigorous discourse, and
>>> neither is this reply. To set the record straight, the Linear No Threshold
>>> (LNT) theory is really an assumption that the probability of a harmful
>>> effect resulting from  exposure to ionizing radiation is directly
>>> proportional to the effective dose. Ionizing radiation is the capitalist
>>> form of radiation which evicts electrons from their molecules. Dose is
>>> defined as the ratio of energy deposited by the radiation to the mass of the
>>> object in which it is deposited. The adjective effective indicates that a
>>> crude attempt has been made to take into account the variability of
>>> effectiveness of different radiation types and the variability of radiation
>>> sensitivity of different organs. It is not possible to make a quantitative
>>> assessment for the scenario described in the article.
>>>            The logical conclusion of the LNT, which has not been validated
>>> empirically, is that any finite dose produces a finite probability for harm.
>>> This is incorrectly translated into the statement that science has shown
>>> there is no safe level of radiation. This is an Orwellian tactic which takes
>>> advantage of two facts. First there is no scientific definition of safe, and
>>> the proponents are implying it is zero probability of harm. Second the
>>> concept of safe is generally treated as binary. Something that is not safe,
>>> ie is unsafe, is dangerous. Hence the implication is that any radiation
>>> exposure is dangerous. Now, given that we live on a radioactive planet, eat
>>> radioactive food, breathe radioactive air, have radioactive bodies and are
>>> bombarded by radiation from outer space, this means we must conclude that
>>> the act of living is dangerous.
>>>            This does however open up an interesting legal possibility. It
>>> seems to me humanity has a right to launch a class action suit against the
>>> religious organizations as representatives of God who, after all, bears the
>>> ultimate responsibility for all this.
>>>            Finally the general consensus is that it is not possible to
>>> obtain statistically significant empirical data with which to test the LNT
>>> assumption in the range of dose equivalents below the regulatory limits. The
>>> situation is similar to attempting to detect a signal buried in noise
>>> without the ingenious signal to noise enhancement techniques employed by our
>>> electrical engineering colleagues. However, given that the assumption
>>> ignores the known complexities of biological responses and fails to predict
>>> observed radiobiological phenomena it is clear that the assumption does not
>>> have a substantial scientific basis.
>> 
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