[ExI] Is tobacco really harmful"?

[Robert Bradbury]

On Wed, Nov 25, 2009 at 8:06 PM, Robert Masters <rob4332000 at yahoo.com>wrote:
>
>
> Tobacco is not the cause of smoking-related disease.  Instead, the cause is
> the chemicals added to tobacco.  Pure, additive-free tobacco is harmless.
>

I would argue that additive-free tobacco is not harmless.  I believe the
consumed chemical byproducts (those exposed to the lung) as a simple result
of burning tobacco (or burning marijuana or even dandelions)  numbers in the
hundreds.  This is a result of the fact that plants tend to be at war with
the insects and so they tend to produce a variety of unusual molecules in an
effort to defeat them.  Plant genomes *are* more complex than mammalian
genomes by roughly a (3:2) ratio (30,000 genes vs. 20,000 genes) with
exceptions when one is looking at the simplest plant genomes.

Human genomes have evolved general systems to deal with foreign /
potentially toxic substances but the selection pressure on these pathways
isn't very strong and may not be optimal.  The metabolism of tobacco smoke
in general in some individuals actually converts non-carcinogenic products
of from tobacco combustion into known carcinogens.  It has nothing to do
with "additives" -- it has to do with differences in human genetic makeups.
 If humans had been subjected to strong selection pressure such that people
who smoked with these genes were all dead before the age of reproduction
then people might be able to smoke with diminished consequences.  But since
that is not the case it is far better to receive ones "fix" from a nicotine
patch than consumption of a cigarette.

Now, once these pathways are clearly known and documented and once the tests
become cheap enough (e.g. at the prices 23andme is offering) one has the
possibility of a segmentation of society into those who can smoke freely and
those who should never be exposed to smoke.  Prejudice on the basis of
genetics (coming soon to a neighborhood corner near you...)

(This is all information that came to my attention ~15 years ago and is all
reasonably well documented in PubMed if you are researching toxin metabolism
and/or cancer and the lungs or liver.  I would expect that by now they have
pinned down the genetic variants in even more detail such that one can look
them up in OMIM or the human SNP databases.)

Oh yes, and did I mention that we live in a brave new world...
R.
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