[ RadSafe ] LNT

[Busby, Chris]

Raabe: NONSENSE!  All studies are based on actual average radiation absorbed
dose to living tissues. This is a physical quantity whether the
source is internal or externa

Busby: It is far from nonsense. This is the problem, Otto. I know that all studies are based on this quantity. But this quantity is not the same as the ionisation density at the DNA. Any schoolkid could work that out with a pencil. Thats why you multiply by 20 for alphas. Why do you think you multiply by 20 for alphas. It used to be callesd relative biologcal effectiveness RBE.  Are you saying that a decay in the cytoplasm has the same carcinogenic effect as a decay in the coiled DNA of an element chemically bound to it? It seems you are. Take tyritium. The beta range is so small that ALL the decays in the cytoplasm are lost energy. So the effects must be due to those few atoms that approach rthe DNA or some other key target. Yet Tritium has a RBE of 1.0. Therefore the few atoms that are near the DNA must have a RBE of several thousand to account for the lost energy ionsining the cytoplasm.  ICRP originally decided as far back as 1972 to add a weighting factor N to internal emitters that bound to DNA. I was told this by one of the ICRP people in Stockholm last year. They dropped the idea. But ECRR picked it up (independently, since we didnt know in 2003 that ICRP had done this).  
Best wishes
C


-----Original Message-----
From: radsafe-bounces at agni.phys.iit.edu on behalf of Otto G. Raabe
Sent: Thu 29/09/2011 17:09
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] LNT
 
At 12:40 AM 9/28/2011, Chris Busby wrote:

>The problem is this question: what is the ionisation density at the 
>target? This includes non targeted effects, then the ionisation 
>density in the cell or cell community. It is clear from experiments 
>with radiation but also other chemical stressors that the dose 
>response in complex, and usually biphasic. As you say, there are 
>different mechanisms at high dose rate than low dose rate. But the 
>local ionisation density is usually orders of magnitude higher for 
>internal than external irradiation and for second event emitters or 
>sequences or cascades the cell may alter its repair state before a 
>second or third hit. My own belief is that hormesis is an artifact 
>arising from a misunderstanding of the position of the point 0,0.
>The current arguments (including the radsafe ones) are very simplistic.
>Chris

NONSENSE!  All studies are based on actual average radiation absorbed 
dose to living tissues. This is a physical quantity whether the 
source is internal or external.




**********************************************
Prof. Otto G. Raabe, Ph.D., CHP
Center for Health & the Environment
University of California
One Shields Avenue
Davis, CA 95616
E-Mail: ograabe at ucdavis.edu
Phone: (530) 752-7754   FAX: (530) 758-6140
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