Re: Again 8 kB

["Bjorn Cedervall" <bcradsafers@hotmail.com>]

Hormesis:
Each one of the different kinds of hormetic effects that has been described 
deserves a context analysis. The experiments with priming doses seem 
concincing. OTOH: Are they relevant from a practical aspect? (should we have 
daily priming doses to trigger our repair enzymes, production of thiols or 
whatever?) I can imagine a number of molecular phenomena that could explain 
such effects. Certain cell lines exhibit initial (up to about 1 Gy which is 
much higher than the doses in the priming dose experiments - can't recall 
the levels but the difference is in the order of magnitudes - I am sure that 
some Radsafers have the data available - say from S. Wolff) steeper slopes 
in their survival curves. These were works by P. Lambin, M. Joiner and 
others since 1992 - see for instance the colorectal cell line HT29. Other 
observations that have were interpreted as hormetic were those where 
increased cell division was observed. Another context is that distinguishing 
individuals from populations (mutation rate experiments). Sorry that I can't 
give exact references - some I read more than 20 years ago and others aren't 
around me at this moment of writing.

One reference I saw a year ago shows that mutations increase linearily (some 
mammalian - probably either mouse or human??) with increasing age 
(supposedly just an effect of background radiation like K 40 etc). I may be 
able to come back to that reference - it is more recent (I have recently 
asked a friend who has the reference to send it to me).

A bottom line is to be cautious in the interpretation that some radiation is 
"healthy" for you - especially if you are interpreting data for individuals 
rather than for populations.

Bjorn Cedervall   bcradsafers@hotmail.com
With the lines above, I represent myself.

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