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Lecture

Lecture 1 Video


Department
Environmental Science
Course Code
EESA10H3
Professor
Jovan Stefanovic

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Video
Everyday carcinogens: Acting for Prevention in the Face of Scientific Uncertainty (Featured by
Dr. Sandra Steingraber)
trying to connect evidence of cancer and the environment together
no one study that constitutes what we in the scientific community would call absolute
proof of a connection between cancer and the environment
owhat exists are many well designed, carefully constructed studies that all together
tell a consistent story
The first line of evidence
oCanadian data or the US data, the overall picture is very similar. 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.
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.
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 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
oLet'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 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
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