Robert Mann wrote:
> The suggestion of scientist speakers for the Jan mtg is very good.
> An obvious choice would be Margaret Mellon PhD JD, chief of the Union of
> Concerned Scientists work on GM. Also you might invite Dr John Losey,
> asst. prof. at Cornell, the leader of the team that published the monarch
> results in _Nature_. And then of course there's Prof. Patrick Brown of UC
> Davis, whose general criticisms of current GM crops I've previously
> recommended. You could also consider a global star, Prof D T Suzuki of UBC -
> one of the most prominent of GM critics.
For the sake of balance, someone to represent the pro-GM point of
view would be good too.
Speaking of balance, below is an interesting interview of Dr. Bruce
Ames, a professor of biochemistry and molecular biology at the University
of California at Berkeley by the editor of Reason Magazine
http://www.reason.com/amesint.html. While it doesn't deal with GM, it
outlines the surprizing state of the art thinking in regard to the apparently
trivial impact of human exposure to conventional chemical pesticides
and industrial chemicals:
Bruce Ames interviewed by Virginia Postrel:
"In the 1970s, Bruce Ames was a hero to environmentalists--the
inventor of the Ames Test, which allows scientists to test chemicals
to see whether they cause mutations in bacteria and perhaps cancer in
humans. His research and testimony led to bans on such synthetic
chemicals as Tris, the flame-retardant used in children's pajamas. A
world renowned cancer researcher with a calm, reasoned manner,
Ames was an ideal witness in the case against man-made chemicals.
But it's a scientist's imperative to change his mind when the data
change-- and recent data have made Ames deeply suspicious of high
dosage chemical testing and especially of the notion that man-made
chemicals are uniquely dangerous. We are, he has discovered,
surrounded by mutagens--not only synthetic chemicals but also
natural ones--and blindly banning suspicious modern substances can
do more harm than good.
Today, Ames, a professor of biochemistry and molecular biology at
the University of California at Berkeley, stands on the other side of
the chemical-ban debate. In 1990, he spoke out against California's
Proposition 128, which would have banned many pesticides, and he
has been highly critical of the ban on Alar. The best way to prevent
cancer, Ames now believes, is to "eat your veggies." Any
government action that makes fruits and vegetables more expensive
ultimately causes cancer.
Ames discussed cancer research and environmental politics with
Editor Virginia Postrel at his Office in Berkeley:
POSTREL: You've become well known for saying that we
shouldn't worry so much about man-made chemicals causing cancer, that
natural carcinogens are far more common and we shouldn't worry
about them either. Why is that?
AMES: Pollution is pretty much irrelevant to cancer--the kind of
pollution that we're getting with water pollution, or with pesticide
residue, is in such tiny amounts.
People got off on the wrong track about man-made chemicals. They
said, Look, we know workers can get cancer from high doses of
beta naphthalene or vinyl chloride. We shouldn't have the workers
be guinea pigs--we should test these things in rats. And that was
reasonable. So they started testing the industrial chemicals in rats.
POSTREL: And they picked these chemicals because
they were known to be associated in high doses with cancer?
AMES: Originally the driving force was high-dose occupational
exposure. but soon it came out to be testing every synthetic chemical
and half of them came out positive in rat tests. I think we're drawing
the wrong conclusions from high-dose rat tests. They are testing
enormously high doses--the maximum tolerated dose in the rats or
the mice, which means you find the level that causes overt toxic
effects and back off just a little bit and feed the animal that amount
every day for a lifetime. That sends toxicologists up the wall because
that's a very high dose, and they are afraid that will do something
that isn't relevant to low doses.
But the control. which people should have thought of but they
didn't, is what about all the chemicals in the natural world? People
got in their head, well, if it's man-made somehow it's potentially
dangerous, but if it's natural, it isn't. That doesn't really fit with
anything we know about toxicology.
When we understand how animals are resistant to chemicals, the
mechanisms are all independent of whether it's natural or synthetic.
And in fact, when you look at natural chemicals, half of those tested
came out positive.
Of course. almost all the world is natural chemicals, so it really
makes you rethink everything. A cup of coffee is filled with
chemicals. They've identified a thousand chemicals in a cup of
coffee. But we only found 22 that have been tested in animal cancer
tests out of this thousand. And of those, 17 are carcinogens. There
are 10 milligrams of known carcinogens in a cup of coffee and that's
more carcinogens than you're likely to get from pesticide residues for
a year!
POSTREL: Why not conclude that you shouldn't drink coffee'
AMES: But half of all the things tested are coming out positive. The
point isn't to worry so much about cups of coffee, but to rethink
what we're doing with animal cancer testing We're eating natural
pesticides, which are natural chemicals that plants use to try to kill
off insects that try to eat them. And we eat roughly 1,500 milligrams
of them per day. We eat 0.09 milligrams of synthetic pesticide
residues. So we're talking about incredibly tiny amounts of synthetic
pesticides, and yet the same percentage of natural chemicals come out
positive.
So then the question is, What's wrong with high-dose animal cancer
tests? I've been arguing in the literature that cell division is a risk
factor for cancer, as is mutation. A mutagen damages your DNA,
and everybody agrees that that's a risk factor for cancer, and cancer
can occur with accumulated mutations. But when the cell divides,
DNA damage is converted to mutations. So what we 'v been arguing
is that raising either increases your risk of cancer--either the rate of
cell division or the rate of mutagenesis. So when you test thes
enormous doses of a chemical, cell division can be caused in various
ways. It's like a chronic wounding experiment. When you wound
tissue. you get a lot of cell proliferation, because you get signals for
the cells to come in and heal the wound and start dividing. So I think
that a sizable percentage of the chemicals are only going to be a risk
factor in high doses--like saccharin.
POSTREL: Because they have this wounding effect?
AMES: Yes, at these enormous doses. Saccharin is a carcinogen at
high doses, and everything we know about the theory says there's
no risk at all at low doses. I think that some sizable percentage of all
the chemicals we're calling carcinogens are going to be like that.
Now if something's a mutagen. it can both damage the DNA and kill
cells. If you get to high enough doses where it's killing cells as well
as damaging the DNA, then you're getting an extra multiplier. For a
mutagen there might be a small risk at any level. But in most cases
you also get this big multiplier that's only a high-dose effect. So all
this says is that the risk numbers people are throwing around are
going to just be wrong. And the further you get from the dose you
gave the rat, the less you want to worry about it.
POSTREL: People do want to know what causes cancer.
AMES: That's what I'm very much interested in. Cancer is primarily
a degenerative disease of old age. It goes up very sharply with age.
Rats live about two to three years and by the end of their lifetime, 30
percent of them have cancer. At 1 year old, very few have cancer.
Mice have a slightly shorter lifespan, and the curve is shifted to the
left. And people show a similar relation, except we live to 80 years.
This suggests that cancer is a degenerative disease of old age, in the
same way as heart disease and cataracts and all the other things you'll
find out about soon enough as you get older.
It doesn't mean that external factors can't influence it--we know
cholesterol influences heart disease, and smoking is 10 years off your
life, so if everybody stopped smoking the curve would move out.
But underlying it all, the reason there is more cancer is more people
are going up that curve. More people are living longer and longer
every year, and as we're living longer we see an increase in cancer.
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