Re: Question on low-dose rad effects

["Ted Rockwell" <tedrock@cpcug.org>]

> the heavier individual gets twice as many ionizing
events occuring near twice as many DNA molecules any one of which might
result in an adverse mutation.  Why doesn't the individual with twice the
mass, get twice the risk???

Jerry:

Because cancer incidence does not result from additional DNA damage.  That
is the most important thing to understand about radiation health effects.
DNA is getting continually damaged by the routine process of metabolism,
millions of times greater than the similar damage from radiation.  The body
is designed to handle such damage, or we'd all die of cancer before our
first birthday.

Radiation-induced cancer occurs only when the radiation level is so high
that it damaged the body's defenses.  The additional effect of the small
number of DNA damaging events caused by low-dose radiation is overwhelmed by
the stimulating effect of the radiation on the body's defenses.

This is an oversimplified answer.  For the full story, read the works of
Pollycove, Feinendegen, Mitchel, et al.  Your question, and the answer,
demonstrates why the LNT is not a valid description of what happens.  Bernie
Cohen has also pointed this out, I believe.

It's not an old-fashioned physics target irradiation problem.  The target is
not inert.  It interacts with the radiation.

Ted Rockwell

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