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toxicity of materials

updated thu 12 may 05


John Hesselberth on wed 11 may 05

Hi Everyone,

With all the discussion of material toxicity the last few days, I
recommend reading an article in the latest (May 2005) issue of National
Geographic about 'poisons'. Of course they have the usual intrigue in
the story by covering things like the theories about how Napolean died.
But their real point is that everything is both a poison and a very
beneficial material. It all depends on the dose. For example we can't
live without water but, at the same time, too much water can result in
hyponatremia which disrupts brain, heart, and muscle function. So water
is, in some sense, a poison. Arsenic was the first effective remedy for
syphilis, and it has been used to 'treat' other problems over the
centuries. According to National Geographic, it is still an effective
chemotherapy treatment for acute forms of leukemia. Of course it has
been a favorite poison for a couple thousand years. It all depends on
your perspective.

The article quotes Paracelsus, a 16th century German-Swiss physician
and alchemist "All substances are poisons; there is none which is not a
poison. The right dose differentiates a poison and a remedy."

Unfortunately we don't always understand "the right dose" and it is
fairly certain that dose is different for different people. My personal
view is that we are wise to be careful and cautious when handling any
material where the toxicity is not reasonably well understood, but
there is no need to be paranoid or spend the rest of our life hiding in
a cave.