Kristen, saying that most cancers are caused by environmental factors
is kind of misleading. If exposure to chemical X will give you cancer
only if you have allele Y, then was the cause of the cancer genetic or
environmental? Of course, the distinction is meaningless, like asking
whether children are caused by their mother or their father.
The question to ask is whether going back to stone age technology would
eliminate most cancers. The answer is yes, since most people would die
before they developed cancer. OK, lets take the question more
seriously. Every plant contains hundreds of different chemical
compounds. Most plants have evolved to contain compounds that are
toxic. One of the major efforts of agriculture over the last ten
thousand years has been to select plants with low levels of toxins, and
selectively breed them for even lower toxicity. Compare the toxicity
of a modern carrot with the toxicity of it's wild cousin, Queen Anne's
lace. Queen Anne's lace tastes incredibly bitter due to all the
anti-herbivory compounds it contains. How many of those compounds are
carcinogenic? Probably most of them.
Imagine if you had to get FDA approval before you could sell broccoli.
I doubt most of the compounds in broccoli have been studied for
carcinogenicity, but imagine having to prove that each one was safe.
But that would be impossible, since several are known carcinogens
anyway.
=====
Darryl
Think Galactically -- Act Terrestrially
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