!! spellx done
102  Can Drinking Coffee Raise
     Chances of Skin Damage?
     The Washington Post, Saturday, June 15, 1968

     Every cell of the human body contains enough giant molecules
of deoxyribonucleic acid (DNA) -- the substance that controls the
transfer of genetic characteristics -- to make up 5 billion units, or
nucleotides.  Whenever a cell divides, a new copy of DNA must be
assembled with the correct sequence of these units.  An error in any
one of them might be a mutation disastrous for the cell and, in the
long run, for the whole organism.

     For many years, this chemical process of replication was
visualized as reliable enough to reassemble 5 billion units during
each cell division without numerous errors, a concept that strains
the imagination.  But it has recently become apparent that living
cells have mechanisms for proofreading and correcting the copy and
that replication itself need not be quite so precise.

     As it happens, this repair mechanism has been pointed up by the
discovery that a hereditary disease, Xeroderma pigmentosum, can be
traced to its failure.

     Cells of the skin are especially vulnerable to DNA damage caused
by exposure to sunlight.  And skin cells of Xeroderma pigmentosum
patients lack means to repair this damage when it occurs.  So the
cells are more easily killed or, on occasion, they mutate to cancerous
forms of growth.

     As often happens, the discovery of a genetic deviation helps to
focus attention more clearly on the normal process.  These
observations reopen questions about other factors that might influence
DNA repair mechanisms.

     In 1950, Drs. Aaron Novick and the late Leo Szilard reported that
caffeine was mildly mutagenic; that is, it increased the rate of
mutational errors in bacterial cells.  Ten years later, in separate
studies, Drs. Evelyn Witkin and Margaret Lieb showed that caffeine
strongly reinforced the mutagenic action of ultraviolet light.  The
most plausible interpretation now is that caffeine mainly interferes
with DNA repairs, rather than injuring DNA directly.

     The possibility that caffeine might be mutagenic has stimulated
some genetic studies on fruit flies and on mice, but the results have
been inconclusive.  For technical reasons, it is far more costly to
study whole animals, or even tissue cells, than bacteria.

     There is no epidemiological evidence linking coffee to cancer;
I doubt it has ever been sought.  Hence it would be premature to
condemn coffee as a public health hazard comparable, say, to
cigarettes.

     The most critical rationale would be to look for an effect of
coffee drinking on the rate of skin cancer among people of light
complexion heavily exposed to sunburn.  So we might survey
Scandinavian skiers -- but I suppose they all drink coffee anyhow.

     It would be reasonable to go easy on drinking coffee, tea or
other caffeine-rich beverages just before or after sunbathing.  But
until there are some relevant statistics or deeper biochemical
insights, this is only a rational speculation.

     We have also begun to understand other mechanisms for repairing
DNA.  Many cells have a "photo-reactivation" enzyme that used blue
wavelengths to repair some damage caused by ultraviolet.  Sunlight
is rich in both, so it stimulates some repair or its own injury.

     Finally, Novick and Szilard's original work showed that some
chemical analogues of caffeine are ANTI-mutagenic, and might be
useful to prevent mutation.  In the light of current concerns about
genetic damage from chemicals, these older observations call for
serious reinvestigation.

----------------------------------------------------------------------