Re: Radiation - net benefit or detriment?

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

>In fact, anyone who has looked at a few years of basic radiation biology
research should recognize that ionizing radiation does cause potentially
harmful DNA damage, initiate beneficial cellular responses, and even
initiate cellular responses in nearby cells.
--------
There is an article (probably Mutation Research and for a mammal - cannot 
remember which - maybe humans) where the number of point mutations in 
somatic cells are shown as a function of age. The number increases as a 
clearly linear function with increasing age (I have seen a graph from this 
article but never got the original in my hand). Much of this is probably a 
reflection of background radiation as well as other phenomena that may cause 
DNA damage. I cannot see why I would want to have a higher slope for this 
function as this slope represents a continuous breakdown of the DNA code and 
ultimately the biochemical and physiological function of my cells.

At least about ten genetic conditions have been discussed in a DNA damage & 
repair context and an association with a speeded up aging process (see C. 
Bernstein and H. Bernstein, Aging, Sex and DNA Repair, Academic Press, 
1991).

All the quantitative work I have seen with radiation induced DNA 
double-strand breaks (DSBs) point at a linear induction with increasing 
radiation dose (those who have a non-linear function most often work with 
the wrong mathematical function - DNA mass instead of DNA DSBs - this is a 
violation of the chain rule for derivatives which some biologists don't want 
to hear about - they have never understood that they multiply their response 
of interest with a sigmoid function). What is biologically interesting is of 
course the remaining DNA/chromosomal  damage after repair and the fraction 
of misrepaired damage.

My personal reflections only,

Bjorn Cedervall   bcradsafers@hotmail.com
http://www.geocities.com/bjorn_cedervall/

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