Ecological Roots, Afterword

excerpted from the book

Living Downstream

a scientist's personal investigation of cancer
and the environment

by Sandra Steingraber

Ecological Roots

We know a lot about bladder cancer. Bladder carcinogens were | among the earliest human carcinogens ever identified, and one of the first human oncogenes ever decoded was isolated from some unlucky fellow's bladder tumor. More than most malignancies, bladder cancer has provided researchers with a picture of the sequential genetic changes that unfold from initiation through promotion to progression, from precursor lesions to increasingly more aggressive tumors.

Sadly, all this knowledge about genetic mutations, inherited risk factors, and enzymatic mechanisms has not translated into an effective campaign to prevent the disease. The fact remains that the overall incidence rate of bladder cancer increased 10 percent between 1973 and 1991. Increases are especially dramatic among African Americans: among black men, bladder cancer incidence has risen 28 percent since 1973, and among black women, 34 percent.

Somewhat less than half of all bladder cancers among men and one-third of all cases among women are thought to be attributable to cigarette smoking, which is the single largest known risk factor for this disease.

Several obstacles, I believe, prevent us from addressing cancer's environmental roots. An obsession with genes and heredity is one.

Cancer research currently directs considerable attention to the study of inherited cancers. Most immediately, this approach facilitates the development of genetic testing, which attempts to predict an individual's risk of succumbing to cancer, based on the presence or absence of certain genetic alterations. These efforts may also reveal which genes are common targets of acquired mutation in the general population. (Hereditary mutations are present at the time of conception, and they are carried in the DNA of all body cells; acquired mutations, which accumulate over an individual's lifetime, are passed only to the direct descendants of the cells in which they arise.)

Hereditary cancers, however, are the rare exception. Collectively, fewer than 10 percent of all malignancies are thought to involve inherited mutations. Between 1 and 5 percent of colon cancers, for example, are of the hereditary variety, and only about 15 percent exhibit any sort of familial component. The remaining 85 percent of colon cancers are officially classified as "sporadic," which, confesses one prominent researcher, "is a fancy medical term for 'we don't know what the hell causes it."' Breast cancer also shows little connection to heredity (probably between 5 and 10 percent). Finding "cancer genes" is not going to prevent the vast majority of cancers that develop.

Risks of lifestyle are also not independent of environmental risks. And yet public education campaigns about cancer consistently accent the former and ignore the latter. I collect the colorful pamphlets on cancer that are made available in hospitals, clinics, and waiting rooms. When I was teaching introductory biology and also spending many hours in doctors' offices, I began to compare the descriptions of cancer in the tracts displayed in the skinny, silver racks above the magazines with the chapter on cancer provided in my students' textbook. Here are some of my findings.

On the topic of how many people get cancer, a pink and blue brochure published by the U.S. Department of Health and Human Services offers the following:

Good News: Everyone does not get cancer. 2 out of 3 Americans never will get it.

Whereas, according to Human Genetics: A Modern Synthesis:

One of three Americans will develop some form of cancer in his or her lifetime, and one in five will die from it.

(Since these materials were published, the proportion of Americans contracting cancer has risen from 30 to 40 percent.)

On the topic of what causes cancer, the brochure states:

In the past few years, scientists have identified many causes of cancer. Today it is known that about 80% of cancer cases are tied to the way people live their lives.

Whereas the textbook contends:

As much as 90 percent of all forms of cancer is attributable to specific environmental factors.

In regard to prevention, the brochure emphasizes individual choice - and responsibility:

You can control many of the factors that cause cancer. This means you can help protect yourself from the possibility of getting cancer. You can decide how you're going to live your life- which habits you will keep and which ones you will change.

The genetics book presents a somewhat different vision:

Because exposure to these environmental factors can, in principle, be controlled, most cancers could be prevented.... Reducing or eliminating exposures to environmental carcinogens would dramatically reduce the prevalence of cancer in the United States.

The textbook goes on to identify some of these carcinogens, the routes of exposure, and the types of cancer that result. In contrast, the brochure emphasizes the importance of personal habits, such as sunbathing, that raise one's risk of contracting cancer. Thus, in my students' textbook, vinyl chloride is identified as a carcinogen to which PVC manufacturers are exposed, whereas in the brochure, occupations that involve working with certain chemicals are called a risk factor. The textbook declares that "radiation is a carcinogen." The brochure advises us to "avoid unnecessary X-rays." Both emphasize the role of diet and tobacco.

In its ardent focus on lifestyle, the Good News brochure is typical of the educational pamphlets in my collection. By emphasizing personal habits rather than carcinogens, they frame the cause of the disease as a problem of behavior rather than as a problem of exposure to disease-causing agents. At its best, this perspective can offer us practical guidance and the reassurance that there are actions we as individuals can take to protect ourselves. (Not smoking, rightfully so, tops this list.) At its worst, the lifestyle approach to cancer is dismissive of hazards that lie beyond personal choice. A narrow focus on lifestyle- like a narrow focus on genetic mechanisms-obscures cancer's environmental roots. It presumes that the ongoing contamination of our air, food, and water is an immutable fact of the human condition to which we must accommodate ourselves. When we are urged to "avoid carcinogens in the environment and workplace," this advice begs the question. Why must there be known carcinogens in our environment and at our job sites?

The experience of the anthropologist Martha Balshem is revealing here. In the late 1980s, Balshem served as a health educator in an industrial, working-class community near Philadelphia where cancer rates were discovered to be unusually high. In response, the cancer control program of which she was part launched a public outreach campaign urging residents to adopt healthier lifestyles. The residents themselves suspected environmental causes and reported to the educational team that many neighborhood dogs were also afflicted with cancer: Did their pets have faulty personal habits as well? In her book Cancer in the Community Balshem recalls:

As representatives of the cancer center, we sought to deflect this concern and stressed lifestyle changes to reduce cancer risk. Privately, we acknowledged our own feelings or suspicions that the profound pollution we observed in the community was somehow linked to the high cancer rates. We said to each other that this did not present us with a moral dilemma, because in any case, people were well advised to quit smoking, improve their diets, and get regular cancer tests.

In the end, Balshem came to believe the lesson she was transmitting "accept authority and accept blame"-was the wrong one.

The orthodoxy of lifestyle today finds its full expression in the public educational literature on breast cancer. In scores of cheerful pamphlets, women are exhorted to exercise, lower the fat in their diets, perform breast self-examinations, ponder their family history, and receive regular mammograms. "Delayed childbirth" (after age twenty) is frequently mentioned as a risk factor. (I have never seen "prompt childbirth" in the accompanying list of cancer prevention tips-undoubtedly because such advice would be tantamount to advocating teenage pregnancy.)

All by itself, a lifestyle approach to preventing breast cancer is inadequate. First, the majority of breast cancers cannot be explained by lifestyle factors, including reproductive history. We need to look elsewhere for the causes of these cancers. Second, mammography and breast self-examinations are tools of cancer detection, not acts of prevention. The popular refrain "Early detection is your best prevention!" is a non sequitur: Detecting cancer, no matter how early, negates the possibility of preventing cancer. At best, early detection may make cancer less fatal, allowing us, as the epidemiologist Robert Millikan puts it, "to live in a toxic soup without breasts or prostates, et cetera."

Finally, the adage that high-fat Western diets are the cause of breast cancer has not yet been supported by data. Dietary fat has long been a centerpiece of study in the investigation of breast cancer risk.

And yet, several long-term, heavily funded studies have indicated that dietary fat is unlikely to play a major role by itself. Rather than continuing to focus single-mindedly on the absolute quantity of fat consumed, several researchers have called for a more refined, ecological approach to diet. Two obvious starting points would be to assess the link between breast cancer and diets high in animal fat and to launch a definitive investigation into the extent to which various kinds of fats are contaminated by carcinogens. We already know with certainty that animal-based foods are our main route of exposure to organochlorine pesticides and dioxins. It's time to look at the whole picture.

In my own home state, a recent county-by-county cancer report reproduced an old cancer pie chart, published originally in 1981, that relegated environmental factors to a single, tiny slice and depicted tobacco and diet as major risk factors. The report concluded, "Many persons could reduce their chances of developing or dying from cancer by adopting healthier lifestyles and by visiting their physicians regularly for cancer-related checkups." The fact that Illinois is a leading producer of hazardous waste, a heavy user of pesticides, and home to an above-average number of Superfund sites is neither mentioned nor considered. No attempt is made in this report to correlate cancer statistics with Toxics Release Inventory data. No attempt is made in this report to determine whether cancer might follow industrial river valleys, rise in areas of high pesticide use, or cluster around contaminated wells.

During the last year of her life, Rachel Carson discussed before a U.S. Senate subcommittee her emerging ideas about the relationship between environmental contamination and human rights. The problems addressed in Silent Spring, she asserted, were merely one piece of a larger story-namely, the threat to human health created by reckless pollution of the living world. Abetting this hidden menace was a failure to inform common citizens about the senseless and frightening dangers they were being asked, without their consent, to endure. In Silent Spring, Carson had predicted that full knowledge of this situation would lead us to reject the counsel of those who claim there is simply no choice but to go on filling the world with poisons. Now she urged recognition of an individual's right to know about poisons introduced into one's environment by others and the right to protection against them. These ideas are Carson's final legacy.

According to the most recent tally, forty possible carcinogens appear in drinking water, sixty are released by industry into ambient air, and sixty-six are routinely sprayed on food crops as pesticides. Whatever our past exposures, this is our current situation.

After having carefully appraised the risks and losses that we have endured by tolerating it, we can begin to imagine a future in which our right to an environment free of such substances is respected. It is unlikely that we will ever rid our environment of all chemical carcinogens. However, as Rachel Carson herself observed, the elimination of a great number of them would reduce the carcinogenic burden we all bear and thus would prevent considerable suffering and loss of human life. Three key principles can assist us in this effort.

One is the idea that public and private interests should act to prevent harm before it occurs. This is known as the precautionary principle, and it dictates that indication of harm, rather than proof of harm, should be the trigger for action-especially if delay may cause irreparable damage. Central to the precautionary principle is the recognition that we have an obligation to protect human life. Our current methods of regulation, by contrast, appear governed by what some frustrated policymakers have called the dead body approach: wait until damage is proven before action is taken. It is a system tantamount to running an uncontrolled experiment using human subjects.

Closely related to the precautionary principle is the principle of reverse onus. According to this edict, it is safety, rather than harm, that should necessitate demonstration. This reversal essentially shifts the burden of proof off the shoulders of the public and onto those who produce, import, or use the substance in question. The principle of reverse onus requires that those who seek to introduce chemicals into our environment first show that what they propose to do is almost certainly not going to hurt anyone. This is already the standard we uphold for pharmaceuticals, and yet for most industrial chemicals, no firm requirement for advance demonstration of safety exists. But chemicals are not citizens. They should not be presumed innocent unless proven guilty, especially when a verdict of guilt requires some of us to sicken and die in order to demonstrate the necessary evidence.

Finally, all activities with potential public health consequences should be guided by the principle of the least toxic alternative, which presumes that toxic substances will not be used as long as there is another way of accomplishing the task. This means choosing the least harmful way of solving problems-whether it be ridding fields of weeds, school cafeterias of cockroaches, dogs of fleas, woolens of stains, or drinking water of pathogens. Biologist Mary O'Brien advocates a system of alternatives assessment in which facilities regularly evaluate the availability of alternatives to the use and release of toxic chemicals. Any departure from zero should be preceded by a finding of necessity. These efforts, in turn, should be coordinated with active attempts to develop and make available affordable, nontoxic alternatives for currently toxic processes and with systems of support for those making the transition-whether farmer, corner dry-cleaner, hospital, or machine shop. Receiving the highest priority for transformation should be all processes that generate dioxin or require the use or release of any known human carcinogen such as benzene and vinyl chloride.

The principle of the least toxic alternative would move us away from protracted, unwinnable debates over how to quantify the cancer risks from each individual carcinogen released into the environment and where to set legal maximum limits for their presence in air, food, water, workplace, and consumer goods. As O'Brien observed, "Our society proceeds on the assumption that toxic substances will be used 17 and the only question is how much. Under the current system, toxic chemicals are used, discharged, incinerated, and buried without ever requiring a finding that these activities are necessary." The principle J of the least toxic alternative looks toward the day when the availability of safer choices makes the deliberate and routine release of chemical carcinogens into the environment as unthinkable as the practice of slavery.



One preeminent researcher ... John Bailar, ... just published an update of his famous 1986 study, "Progress against Cancer?" ... Titled "Cancer Undefeated," Bailar wastes no words. "In 1986, we concluded that 'some 35 years of intense effort focused largely on improving treatment must be judged a qualified failure.' Now with 12 more years of data and experience, we see little reason to change that conclusion." Bailar's statistical analysis confirms that the slight decline in overall cancer death rates in recent years largely reflects declines in smoking rates-not successes in treating disease. He argues for a redirection of cancer research dollars away from treatment and toward prevention, including removing carcinogens from the environment. A similar conclusion was reached ... by another prominent team of cancer researchers at the National Institute on Environmental Health Sciences, the National Cancer Institute, the National Institute of Occupational Health and Safety, and their colleagues in France and Sweden:

Effective primary prevention resulting in a reduction of cancer risk can be obtained by: (i) a reduction in the number of carcinogens to which humans are exposed; or (ii) a reduction of the exposure levels to carcinogens. Exposure levels that could be seen as sufficiently low when based on single agents may actually not be safe in the context of the many other concomitant carcinogenic. . . exposures.

Nowhere is the focus on cancer prevention more urgent than it is with children. The ongoing rise in childhood cancer incidence in the United States made front-page headlines in the summer of 1997. But the real news came out of Great Britain. A 1997 study by the esteemed British cancer researcher E. G. Knox provides the most detailed picture yet of the close association between childhood leukemias and local environmental hazards. Knox and his colleagues mapped the home residences of all 22,458 children who had died from leukemias and other cancers in England, Wales, and Scotland between 1953 and 1980. (Unlike the United States, England and Wales have a comprehensive national cancer registry that dates back to 1950; cancer mortality data have been collected and analyzed for over a century.) Using atlases and business directories, the Knox team also charted the locations of every potentially hazardous site-ranging from power plants to neighborhood auto body shops. They then combined the two maps. Their findings reveal that children face an increased risk of cancer if they live within a few kilometers of certain kinds of industries-especially those involving large-scale use of petroleum or chemical solvents at high temperatures. These include oil refineries, air fields, paint makers, and foundries. The danger is greatest within a few hundred meters and tapers off with distance. Among children who had moved within their lifetimes, the relationship was stronger for their birth address than it was for their address at the time of their death. This result strongly suggests that very early- probably prenatal-exposures to environmental carcinogens create the threat of cancer in children.

... British and American studies both point to the exquisite vulnerability of the fetus to cancer-causing chemicals. And yet, our respective governments have historically set standards of exposure to environmental carcinogens with adults, not embryos, in mind. What is needed is a new approach to chemical regulation that acknowledges our duty to protect pregnant women from harm. Here is one possible benchmark: if a chemical is not safe for a six-week-old embryo, it is not safe and should not be allowed into the environment.

The power of community right-to-know is growing. In California, home to one of the only pesticide right-to-know laws, public interest researchers documented that overall pesticide use in the state rose 31 percent between 1991 and 1995 and that the use of carcinogenic pesticides had more than doubled. They were also able to attribute this dramatic change to an increase in the amount of pesticides used per acre since the number of acres under cultivation did not change significantly during this period. This report sparked a public debate about the state's agrochemical dependencies.

... basic toxicity testing results still cannot be located in the public record for nearly three-quarters of the top-volume chemicals in the United States. Two-thirds of the most widely used chemicals have still not gone through basic carcinogenicity tests. Meanwhile, production of these basic chemicals continues to rise at a growth rate of 3.3 percent each year...

A new study from Alaska reports that refueling cars with gasoline at self-service pumps provides brief exposure to several known carcinogens. People who had just finished filling up their tanks, researchers discovered, had elevated levels of a variety of volatile gasoline by-products in both their blood and exhaled breath. A study of homes that had been fogged with pesticides by professional exterminators found that the airborne residues continued to accumulate on children's toys for at least a week following the spraying. The foam, cloth, and plastic of children's toys apparently attract semivolatile pesticides from the air to their surfaces where they adhere-until transferred to young fingers and tongues. The authors of this study estimate that children with high frequency mouthing behavior" may be exposed to pesticide levels that are 20 times higher than the recommended safe dose. Current regulations governing professional extermination of household pests do not consider this route of exposure, however.

A new study from Finland provides new evidence on the hazards of chlorinated drinking water. Researchers examined a single byproduct of water chlorination that appears to be a more potent carcinogen than the trihalomethanes ... Known to water chemists as MX (its real name is 3-chloro-4-[dichloromethyl]-5hydroxy-2[5H]-furanone), this chemical offspring of water disinfection practices had never before been tested for its potential to contribute to cancer. Using animal assays, Finnish researchers found that MX acted as a potent carcinogen in both male and female rats even in the lowest dosages administered. Cancers induced in the rats by MX exposure included pancreatic, liver, lung, and breast tumors as well as leukemias and Iymphomas. These do not completely correspond to the same kinds of cancers that humans are prone to contracting from chlorinated water, so the relevance of these animal studies for us is not yet clear. Certainly, however, we have more reasons than ever to protect watersheds from pollution by organic matter, which serves as raw material for the creation of MX as well as trihalomethanes. It is also time to explore alternative methods of disinfection.

Various success stories show us that we are taking unnecessary - risks when good alternatives exist. The game of golf is one example. A new occupational study indicates that golf course superintendents die more often from cancer than the general population. Like farmers, the keepers of golf courses have excess rates of Iymphoma as well as cancers of the brain and prostate. This study does not reveal whether pesticide exposure is the culprit, but we do know that a typical golf course uses four times more pesticides per acre than an agricultural field. Nevertheless, a handful of golf courses in California and Colorado have gone completely chemical-free. By planting grass species suited to the climate, reintroducing native flora, and changing mowing practices, the superintendents of these pesticide-free courses not only protect their own health but also present an important challenge to the assumption that pesticide-intensive turf management is only way to create a fairway or a green.

Alternatives to waste incineration also abound. The need for such alternatives is underscored by the recent decision of the International Agency for Research on Cancer to upgrade the carcinogenic designation of dioxin (TCDD) from "probable" to "known" in light of new, damning scientific evidence. A few months after this announcement, I toured the waste management operation at the Medical Center Hospital in Burlington, Vermont. It is brilliantly organized. This hospital now incinerates less than a truckload of garbage (one half of one percent of its total waste) each year, and it consists almost exclusively of pathological waste and cell cultures.

(The day I visited, the largest object in the container destined for the incinerator was a carefully wrapped placenta from obstetrics.) Other medical waste is sterilized and landfilled. The remainder-over 80 percent of the hospital's total volume of waste-is recycled. No plastic, mercury, batteries, or other hazardous material ever meets the flame. Food waste from the cafeteria and coffee shop is composted and used as fertilizer on nearby organic gardens, and the resulting produce is sold back to the hospital.


The release and use of toxic substances, the exploitation of resources, and physical alterations of the environment have had substantial unintended consequences affecting human health and the environment. Some of these concerns are high rates of learning deficiencies, asthma, cancer, birth defects and species extinctions, along with global climate change, stratospheric ozone depletion and global worldwide contamination with toxic substances and nuclear material.

We believe existing environmental regulations and other decisions, particularly those based on risk assessment, have failed to protect adequately human health and the environment-the larger system of which humans are but a part.

We believe there is compelling evidence that damage to humans and the worldwide environment is of such magnitude and seriousness that new principles for conducting human activities are necessary.

While we realize that human activities may involve hazards, people must proceed more carefully than has been the case in recent history. Corporations, government entities, organizations, communities, scientists and other individuals must adopt a precautionary approach to all human endeavors.

Therefore, it is necessary to implement the Precautionary Principle: When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. In this context, the proponent of an activity, rather than the public, should bear the burden of proof.

The process of applying the Precautionary Principle must be open, informed and democratic and must include potentially affected parties. It must also involve an examination of the full range of alternatives, including no action.

Living Downstream

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