Ecological Roots, Afterword
excerpted from the book
a scientist's personal investigation of cancer
and the environment
by Sandra Steingraber
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
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
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
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
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
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
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
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
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
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
(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.
WINGSPREAD STATEMENT ON THE PRECAUTIONARY PRINCIPLE
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.