Re: The Unknown and the Unknowable

[John Jacobus <crispy_bird@YAHOO.COM>]

Jerry,

Well said.  



--- Jerry Cohen <jjcohen@PRODIGY.NET> wrote:

>      There are similarities between two seemingly

> unrelated issues  currently under discussion. These

> are the LNT hypothesis, and global climate change.

>     Both involve scientific vs.

> morality/ethics/religion considerations as

> encompassed in the "precautionary principal". A

> perhaps more important similarity is the fact that

> both involve factors that are not only unknown, but

> unknowable. Science thrives on resolving

> uncertainties and bringing previously unknown facts

> to light, but we cannot do much with the unknowable.

> To trick is to

> distinguish the unknown from the unknowable so that

> resources are not wasted trying to gain an

> understanding of things inevitably beyond our

> comprehension.

>     We know, for example, that the planet has

> existed and major climate changes  have occurred for

> millions of years---well before humans came on the

> scene. The earth has experienced ice ages, and hot

> spells periodically throughout its history. We have

> little, if any, understanding of what caused such

> changes, but most likely major cosmic events such as

> sun spots and others solar phenomena have played a

> significant role. So the climate has changed well

> before the previous few centuries during which man

> has been able to record such events. Of course we

> can't know for certain, but it seems reasonable to

> assume that climate change will continue to occur in

> the future, with or without man's intervention.

> IMHO, the impact of man's activities is puny

> compared to that of cosmic events over which we have

> no control. It seems presumptuous, if not arrogant

> to believe that we have the power to cause major

> climate change. In any case, it is not possible to

> prove one's case in this regard one way or another

> since we will never know the initiating events that

> caused major climate changes in the past.

> Nevertheless, it is likely that much of our limited

> resources will continue to be squandered in the

> attempt to do so, as well as in controlling  CFC's,

> Carbon Dioxide, and other factors presumed to be

> harmful to the climate, based on applying the

> precautionary principle.

> 

>     The effects of low-dose radiation (LDR) exposure

> to man is also unknowable, unless one takes the

> narrow view of ICRP, NCRP, etc. that DNA aberrations

> are the only LDR effects worthy of consideration. If

> that were the case, than perhaps LNT might be a

> reasonable presumption. However, we now have

> abundant evidence that there are multiple radiation

> effects, some harmful in nature and some beneficial.

> Each tissue system, each organ system, may elicit

> its own unique response when challenged by

> radiation. The net effect to the dose recipient is

> the  sum of all such effects. Furthermore, each

> individual can show a unique set of responses at

> various dose levels such that at the same dose level

> some individuals could show net benefit, while

> others a net harm. Therefore, a multiplicity of

> factors determine whether a given low radiation dose

> causes net benefit or net harm, and the degree to

> which such effects might occur. Because of the

> complexity these factors, and how they might vary

> among individuals, it is unlikely that we shall ever

> gain a complete understanding of the net effect of

> LDR on complex organisms.. 

>     For high dose exposure, the problem is easy. If

> one receives an exposure of 10,000 rad, they die.

> Other effects that may occur are unimportant.

> However at low doses (<10 rad), because of the

> complexity of response, only God knows  the net

> effect (but is apparently unwilling to share that

> knowledge with the ICRP).

> 





=====

-- John

John Jacobus, MS

Certified Health Physicist

e-mail:  crispy_bird@yahoo.com



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