From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Fri Sep 12 2003 - 11:59:45 MDT
On Fri, 12 Sep 2003, Robbie Lindauer wrote:
> My point is simply this:
>
> Modern concepts of causation are not deterministic. In our current
> understanding of the causes of cancer, both age and toxins are factors.
Like hell they are not (deterministic) -- its pretty clear at this point
if you have certain mutations in the p53 gene (or a number of other tumor
suppressor genes) they will become nonfunctional and you will likely
develop cancer at some point.
> On this I think we all agree. Take away the toxins - who knows. Take
> away the age - who knows. After that it's ALL conjecture.
As has been noted, some low level of toxins may be helpful. Taking
them away entirely could be quite harmful. Whether this will be the
case depends on individual genetic makeup. So while it may be a
"who knows" situation now because we cannot genotype every single
individual affordably -- it will *not* be a "who knows" situation
in the future when we have that technological capability. The
bottom line will be that toxins are harmful to some -- but not others.
With respect to "age" it is the same problem -- you either have
a genotype that allows one to be susceptible to cancer or one
does not. Human cells accumulate mutations in the genetic
program over time. Thus the longer one has lived the greater
the chances that one has accumulated mutations that will cause
cells to become cancerous. Thus age is linked to cancer. The
people who don't get cancer may simply be thankful that they
die (perhaps prematurely) from some other defect in their genetic
program (or an accident).
Cancer is a process in which genomes become corrupted so that cells
do not behave as the initial genome design dictated. Some of that
may be caused by toxin exposure and some of that may simply be caused
by "living" (e.g. free radical damage caused by normal oxidative
metabolism). Which is more important is not "conjecture" -- it
is a combination of environment and genetics. And there is reasonably
solid data on how different aspects of these bias ones risks.
(For example living in a home with high radon levels definitely
slants one towards cancer -- not "conjecture". But at the same
time not everyone gets cancer and this comes down to genetic
predispositions.)
Robert
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