MARCH 1998 · VOLUME 19· NUMBER 3
An interview with Sandra Steingraber
Ecologist, poet and cancer survivor, Sandra Steingraber, Ph.D. is an internationally recognized expert on the environmental links to cancer. She is the author of Post-Diagnosis, a volume of poetry, and co-author of a work on ecology and human rights in Africa, The Spoils of Famine. She has taught biology and held visiting fellowships at several universities, and was recently appointed to serve on President Clinton's National Action Plan on Breast Cancer. She was named Ms. Magazine's 1997 Woman of the Year, and is the author of 1997's highly acclaimed Living Downstream: An Ecologist Looks at Cancer and the Environment.
Multinational Monitor: What made you decide to write Living Downstream?
MM: And what did you find?
MM: They can look at the cancer cells of a human being and determine
which carcinogen caused the cancer?
We'll never have what my detractors might call absolute proof. First, absolute proof in science in very rare. Second, it would require controlled human studies. That is, having two populations and exposing one human group to known amounts of certain chemicals and then watching the results. We will never do that. So, we will always have to infer from humans that have been inadvertently exposed to unknown amounts of chemicals for unknown amounts of time, from lab animal studies, from wildlife studies and from cells growing in a petri dish. We will have to do the best we can and use our judgment.
I argue in Living Downstream that more and better data should never be a substitute for good judgment. At some point, there is enough information to act in a precautionary manner to protect human health.
MM: You have cancer, is that right?
MM: How old were you when you learned of this?
MM: How are you doing?
MM: Do you believe the environment caused your cancer?
It turns out that bladder cancer is the classic environmental cancer. The evidence on bladder cancer and its relationship to environmental contaminants is stronger than most diseases. Exposure to contaminants in tap water is a pattern I found over and over again in human studies that looked at whole populations.
That gave me grounds years later to go back to my hometown -- Pekin, Illinois -- and become a kind of environmental detective there. Pekin is just downstream from Peoria.
MM: You mentioned that molecular biologists now can go and look
at a person's cancer and determine what carcinogen caused it. Did they
do that for you?
Why is there this lack of curiosity on the part of the medical community about the causes of cancer? Part of the answer to that is simply that doctors don't need to know the cause of the disease in order to treat it. You can have your tumor successfully treated by a whole variety of methods without the doctor knowing anything about what might have triggered it. On the other hand, I do believe the medical community has a responsibility to get curious about these things and ask these questions. If they don't, they may be returning their patients to a very toxic environment where they may be exposed to some of the very same carcinogens that caused the cancers in the first place -- whether it's a workplace or home environment.
MM: What are your suspicions as to the causes of your cancer?
Dry cleaning fluids are chemicals with suspected links to bladder cancer. Do I think that's what caused my cancer? I don't know. It is like asking which straw broke the camel's back. We know that you need about eight to 10 mutations to a single cell before that cell is placed definitively on the pathway to tumor formation. One of the straws in that heap on your back might be from the environment, another might be from genes that you inherited, another might be from a lifestyle choice like smoking.
But it seems to me that no matter how large or small the burden is from the environment, it is a human rights issue. Unlike lifestyle choices, those are risks that we have not consented to. Unlike hereditary contributing factors, we can do many things about toxics in the environment. There is nothing we can do about our ancestors. Cancer genes play a role in maybe 5 to at most 10 percent of all cancers. That 5 or 10 percent of the puzzle we can do nothing about.
All of that logically argues for looking at the environment as a place to begin a meaningful program of cancer prevention.
MM: How do we know that cancer genes only cause 10 percent of the
MM: Does that mean that 90 percent of cancers are caused by lifestyle
and toxics in the environment?
We know for a fact that 90 to 95 percent of those of us who contract cancer are born with a perfectly healthy set of genes to which something bad happens during our lifetimes. Any one cancer might be caused both by mutations from lifestyle and by mutations from the environment. And you cannot always untwist these two variables from each other -- they are not independent of each other.
Consider high-fat diet, which has been implicated as a classic lifestyle risk factor in several big-ticket malignancies. Why is high-fat diet associated with several cancers? Of all the foodstuffs, animal fat is the substance in our diet that is the most heavily contaminated with dioxins as well as very persistent pesticides that bioaccumulate as you move up the food chain. The fatty portion of the meat, milk or eggs is what is carrying the huge load.
So, on the one hand, fat is a lifestyle choice, but on the other hand, it is also a vehicle for carrying fat-soluble carcinogens into our bodies.
If we weaned U.S. agriculture from its dependency on pesticides and stopped incinerating plastic waste, which is a major source of dioxin production, we could get these chemicals out of animal fat and people could choose to eat what they want to eat. Perhaps a high-fat diet would not carry such a cancer risk.
MM: How geographically concentrated is cancer in the United States?
But there are other cancers that show very different patterns. One of them is non-Hodgkins lymphoma. It is one of the more swiftly rising cancers right now. It has tripled in incidence rate over the past 50 years. It has no known lifestyle risk factors. It has no known hereditary risk factors. And it is rising the fastest. It is the cancer that killed Jackie Kennedy Onassis, so it is getting more attention now.
If you looked at the mortality map of non- Hodgkins lymphoma, you would light up in red the central part of the United States -- the Midwest and Great Plains area. That is the part of the country where we use pesticides in agriculture most intensively. That correlation does not necessarily indicate cause, but it certainly does give us grounds for further inquiry.
When you look more closely at the possibility that pesticides are playing a role in non-Hodgkins lymphoma, you find some interesting studies. For example, dogs whose owners regularly use certain kinds of weed killers have twice the rate of canine non-Hodgkins lymphoma than dogs whose owners don't use these lawn chemicals. If you look by occupation at who gets non-Hodgkins, you find that farmers, golf course supervisors and Vietnam Vets exposed to Agent Orange have higher rates of non-Hodgkins than folks in the general population. Those are all occupations that have exposure to pesticides.
In the molecular biological literature, there are studies by Dr. Vincent Garry at the University of Minnesota about what kinds of mutations pesticide exposure causes. He looked at a population of pesticide applicators and found they had a very unusual mutation in one of the middle chromosomes. The chromosome actually breaks off, flips upside down and reattaches itself. It is called a chromosome inversion. The only other population besides pesticide applicators where he has seen that kind of mutation in high frequency are non-Hodgkin lymphoma patients.
All of the evidence -- the occupational literature, the cancer maps, the cancer registry data, animal studies, and studies from inside humans themselves -- is pointing to certain pesticides playing some kind of role in the increase of certain cancers.
MM: But the idea that genes cause cancer is grabbing more of the
Now we have two powerful databases: the Toxic Release Inventory [which includes extensive information data on industry pollution emissions] and the cancer registries, which measure the incidence of cancer in every county of every state. Together, they give us the ability to ask questions and get some answers as to whether or not there are relationships between toxic emissions and cancer rates. So, we are seeing a shift in focus in the medical research community. Perhaps the media will be the last to come on board. But I've seen a shift in reporting in the last year or two, with more emphasis on the environment.
MM: What were the reviews like for Living Downstream?
MM: Who reviewed the book for the New England Journal of Medicine?
MM: What did he say?
MM: What was your response to the review?
MM: Berke signed his name to the review with a home address and
didn't reveal that he was with Grace.
MM: What are the implications of focusing on prevention of environmental
causes of cancer? Does it mean shutting down the petrochemical industry?
MM: So, are you saying abolish the petrochemical industry?
MM: What would be an example?
Perc is classified as a probable human carcinogen. Eighty percent of the production of perc in the United States is used for dry cleaning clothes. Perc is found in drinking water of communities around the country, it is in the bodies of fresh water fish, it is in ambient air. We are contaminating the world with a chemical that has been strongly linked to human cancer in order to clean our clothes.
I spend most of my time in Boston, where we have a wet cleaner, which relies on soap and water to wash wools and silks. But they have re-engineered washing machines that have computerized controls to control humidity and agitation. It's not like you or I throwing our clothes in the washing machine. And all of my clothes come back looking great. And I know that no one is going to get cancer from cleaning my clothes.
MM: Are you convinced that we can determine which synthetic chemicals
are carcinogenic and which are not?
MM: We don't know what impact reversing the burden of proof will
have on the petrochemical industry. Does it eliminate all plastics? Does
it shut down the industry?