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Lecture

EESA10H3 Lecture Notes - Equal Protection Clause, Radiography, Vagus Nerve


Department
Environmental Science
Course Code
EESA10H3
Professor
Jovan Stefanovic

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Everyday Carcinogens:
Acting for Prevention
in the Face of Scientific Uncertainty
by Dr. Sandra Steingraber
Author, "Living Downstream"
EDITOR'S NOTE: The following is a transcript of Dr. Steingraber's keynote address before the
conference "Everyday Carcinogens: Stopping Cancer Before It Starts". The conference took place at
McMaster University in Hamilton, Ontario, March 26-27, 1999.
Dr. Steingraber is an ecologist and professor and has been appointed to the U.S. National Action Plan
on Breast Cancer; she received her doctorate in biology from the University of Michigan.
Good morning from Boston, Massachusetts.
As a new mom I'm really happy that this kind of technology exists that allows me to bring my
message to you in Canada while still staying at home with my daughter.
"Living Downstream" explores twelve lines of evidence linking cancer and the environment and is
organized into twelve chapters. What I would like to do is talk to you about four of those lines of
evidence fairly quickly just to give you a flavour of how I see these connections working.
But what I want to do first is to kind of give away my main point right up front which is this. There is
no one study that constitutes what we in the scientific community would call absolute proof of a
connection between cancer and the environment.
"Brain cancers among the elderly have jumped 54 per cent just in the last two decades and brain
cancers are also ascendant among children in a remarkable and tragic fashion,"
Instead, what exists are many well designed, carefully constructed studies that all together tell a
consistent story. So I began to see that each of these studies is like a little piece of a jigsaw puzzle. By
themselves they are provocative, but they really only make sense when you bring all the pieces
together and look at how they form a kind of startling picture. And I think it's a picture that we ignore
at our peril.
The first line of evidence I want to discuss briefly comes from cancer registries and this is what
measures the incidence of cancer in a population. Here in the US we don't have a big national cancer
registry. Each state has its own registry. In Canada you do it differently and all the data are pooled
together. And whether you look at the Canadian data or the US data, the overall picture is very
similar. In other words, incidence trends in Canada and the US show a very similar picture. And what
it does show is that non-tobacco related cancers have been rising in incidence among all age groups
from infants up to the elderly, among all ethnicities and among both sexes. And these increases are
definitely apparent since the early '70s. And if you take a longer view, you can see that they go back
to about World War II.

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"We have no life-style factors that we can attribute to the diseases I've just talked about. They are not
related to smoking. They don't seem to be related to diet or exercise. We have eliminated those
possibilities... we need to look at the environment. "
Now changes in hereditary patterns can't account for these increases in cancer. We're not developing
more tumors because we are now sprouting new cancer genes. Nor can improved detection. It is true
that some of the apparent rise in cancers is attributable to better and earlier screening, but the most
swiftly accelerating rates are among those cancers for which we have no effective screening tools.
These include childhood cancers which have more than doubled since I was born in 1959 and have
jumped ten percent in the last decade alone. Another cancer rising really swiftly is testicular cancer
among young men. Testicular cancer tends to strike men between the ages of 19 and 45 and there is
nothing like a mammogram for the testicle. Men are very closeted about this disease. There is not a
lot of public attention about it so when men find a lump they often delay a very long time before
going to a doctor. Because there is not a lot of public education about this disease, because men aren't
required or advised to go in for screening, the fact that testicular cancer has tripled in incidence rate
since World War II in this age group, we believe represents a very real increase in the disease, not an
artificial reflection of better and earlier screening.
Non-Hodgkin's lymphoma is a disease that has doubled in the last four decades. That's getting some
attention now because it killed Jackie Kennedy Onassis and more recently, King Hussein of Jordan,
but we still don't screen people for non-Hodgkin's. Nor do we screen people for multiple myeloma,
which is a painful cancer of the bone marrow. It has also doubled in incidence rate over the last four
decades or so. Brain cancers among the elderly have jumped 54 per cent just in the last two decades
and brain cancers are also ascendant among children in a remarkable and tragic fashion, particularly
among girls under the age of four.
We have no life-style factors that we can attribute to the diseases I've just talked about. They are not
related to smoking. They don't seem to be related to diet or exercise. We have eliminated those
possibilities. Since early and better screening can't explain why the increase is going up, and neither
can heredity because we don't know of any hereditary factors that would explain these diseases, we
need to look at the environment. Again the registry data are not absolute proof of an environmental
connection but they do give us grounds for further inquiry.
A second line of evidence I want to mention comes from computer mapping and this project takes
these same cancer registry data and instead of displaying them over time so that you can look at time
trends, it displays their distribution over space. And when you do this the maps that result clearly
show that cancer is not a random tragedy.
"...the Great Lake Basin is one the places where we see not only breast but colon and bladder cancers,
highest in North America in those places. And of course, the eastern seaboard and the Great Lakes
region ... are the most intensely industrialized areas."
Let's paint for a moment the picture of what breast cancer looks like in North America. So if you can
picture the North American continent in your mind's eye and you wanted to draw the hotspots of
where breast cancer tends to distribute itself .. where do you see the big excesses in breast cancer.
What you would do is colour in red from Maine down to Washington, DC all along the Great Lakes
Basin, including the area where you are now sitting, and the lower part of the Mississippi River from

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Baton Rouge down to Louisiana and also the San Francisco bay area in California. Those areas,
except for the California cluster, also represent the places in the US and Canada where we see the
most bladder and colon cancer. And again the Great Lake Basin is one the places where we see not
only breast but colon and bladder cancers, highest in North America in those places. And of course,
the eastern seaboard and the Great Lakes region and the lower part of the Mississippi River are the
areas where historically are the most intensely industrialized areas. Again these maps don't tell us that
there's a causal connection between industry and cancer. It's a correlation and correlations sometimes
are causative and sometimes there's not. But we need to pay attention to them and it does indicate a
possible hypothesis that we need to investigate further with other kinds of studies.
Now let's draw the picture for non-Hodgkin's lymphoma. Again, conjure up in your mind's eye a map
of North America. You would colour in red the Great Plains areas, particularly Kansas and Nebraska.
I haven't looked at the data to see whether they go up into Manitoba and Saskatchewan or not. I know
the US data better here. But in the United States it's Kansas, Nebraska, Iowa and a little bit in a
shaded pink, Illinois and Wisconsin. And of course, this is where we have the highest intensity of
pesticide use in grain agriculture in those areas. And again, these correlations are not necessarily
causative but they are provocative.
A third line of evidence comes from our own bodies. We know that a whole kaleidoscope of
chemicals linked to cancer exists inside of all of us. These include pesticide residues, industrial
solvents, electrical fluids called PCBs, dry-cleaning fluids are found in the blood and breath of
anyone living in the urban area, and they also include the unintentional by-products of garbage
incineration and, of course, these are the very famous dioxins and furans, which unfortunately play
such an important role in the recent history of Hamilton, Ontario.
These chemicals are found in various places in our bodies. They don't all go to one place, depending
on the specific biochemistry of each one, they partition themselves in different organs and places in
the body. I'm happy to answer questions about what goes where but in general where we've seen these
chemicals turn up are breast milk, body fat, blood serum, semen, umbilical chords, hair, placentas
and even in the fluid surrounding human eggs. So even before conception we know that we have
exposure to chemicals that in the laboratory are linked with cancer. We do not know with certainty
what the cumulative effect of all these multiple exposures is. All we can say is we know we have
chemicals linked to cancer, both known carcinogens and suspected carcinogens, inside all the bodies
of people who live in North America.
But we are not in the dark completely, even though we don't know all the interactive effects,
everything about multiple exposures. There are some areas of this very new and confusing science
that are becoming clearer and clearer.
For example, we are honing in on the various biological mechanisms by which these chemicals seem
to be working their ill-effects. The old scientific thinking was that in order to cause cancer a chemical
had to mutate your genes, it had to cause some kind of damage on your chromosomes. Chromosomes
are the part of your body that's made of DNA and the genes lie along the chromosomes like beads on
a chain. And its damage to those beads that we call mutations and we know that mutations are
necessary for cancer to form. We think about eight to ten mutations are actually required before a cell
is put on the pathway to cancer formation. So the old thinking was, well, if something didn't cause
mutation then it probably didn't cause cancer. "... the new science is showing us that we can't just
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