Canadians Against Pesticides
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 apponited 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.
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.
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.