Animals, Earth, Air, Water,
Our Bodies Inscribed
excerpted from the book
a scientist's personal investigation of cancer
and the environment
by Sandra Steingraber
Vintage Books, 1998 (paper)
When lead was outlawed as an antiknock additive in gasoline, benzene
replaced it. We are therefore exposed to benzene every time we
fill our cars with gasoline. Benzene is classified as a known
Without ... tests, we can only guess at the number of chemical
carcinogens in our midst. As of 1995, the National Toxicology
Program had completed animal assays on 400-odd chemicals. Based
on these results, researchers have estimated that of the 75,000
chemicals now in commercial use, somewhat fewer than 5 to 10 percent
of these might reasonably be considered carcinogenic in humans.
Five to 10 percent means 3,750 to 7,500 different chemicals. The
number of substances we have identified and regulate as carcinogens
is, at present, less than 200.
In 1950, fewer than 20 species of insects showed signs of pesticide
resistance. By 1960, Rachel Carson had documented an alarming
137 species resistant to at least one pesticide and urged that
we should hear in this statistic the early rumblings of an avalanche.
She was right. By 1990, the number of pesticide-resistant insect
and mite species stood at 504.
In creating pests impervious to the arsenal of chemical weapons
directed at them, the story of herbicides reiterates the story
of insecticides. Herbicide-resistant weeds are not mentioned in
Silent Spring, as they did not yet exist. Today, weed scientists
have identified 273 such species. In tracing the explosion of
herbicide resistance among weed species that began in the late
1980s, researchers conducting a recent study were forced to conclude
that the "short-term triumphs of new pest control technologies
have carried with them the seeds of long-term failure."
Since synthetic pesticides were introduced into agriculture at
the end of World War II, total crop loss due to insect damage
has doubled-from 7 percent in the 1940s, when all agriculture
was essentially organic, to 13 percent by the end of the 1980s.
Higher yields have more than offset this forfeiture, and reliance
on pesticides is still economical in the short run. But the pests
clearly have not been bludgeoned into submission. When grown in
rotation, corn had few insect pests, for example. In 1945, almost
none of the U.S. corn acreage was treated with insecticides. Crop
losses due to insects, according to the U.S. Department of Agriculture
(USDA) averaged 3.S percent. Now less than half of corn is grown
in rotation, and corn is the largest user of insecticides. Despite
the more than 1,000-fold increase in the use of insecticides on
corn, losses to insects now average 12 percent.
In one recent study, researchers compiled a variety of agricultural
censuses and surveys to investigate changing pesticide use in
specific U.S. regions. In all three regions they examined-Sun
Belt, Wheat Belt, and Corn Belt-reliance on pesticides in general,
but especially herbicides and fungicides, has grown substantially
since the 1960s, both in intensity (amount of chemicals used per
acre) and extensiveness (percentage of cropland treated). In many
cases, these increases continued into the early 1990s-contrary
to the commonly held belief that pesticide use had become more
judicious. The rate of increase, however, began to stabilize in
the 1980s, and the use of insecticides has actually begun to decline-in
part because of the banning of toxaphene in 1982, in part because
newer formulations of pesticides are more acutely toxic at smaller
doses, and in part because some farmers are moving toward more
ecologically based methods of insect control.
The vegetable fields and fruit orchards of the Sun Belt, according
to this study, receive the highest rates of application-especially
of insecticides and fungicides. Dates, peaches, grapes, and tomatoes
are sprayed with more fungicide (as measured in pounds of active
ingredient per acre) than any other crops, for example. Pear,
on the other hand, top the list of crops most heavily sprayed
with insecticides. Corn ranks only eighteenth on the herbicide
list. But because we grow so much of it, this crop alone consumes
53 percent of the total herbicides used in this country. Together.
corn and soybeans are responsible for nearly three-quarters of
all herbicides used, which in turn account for the majority of
all pesticides used. In short, Corn Belt weeds have become the
number one target of agrochemical warfare.
By 1993, according to the Illinois Agricultural Statistics Service,
herbicides were applied to 99 percent of corn and bean acreage.
Lest anyone assume that the habitudes of warfare are no longer
part of chemical pest control, here are the trade names of some
the ones in common use: Arsenal, Assault, Assert, Bicep, Bladex,
Bullet, Chopper, Conquest, Contain, Dagger, Lasso, Marksman, Prowl,
Rambo, Squadron, Stomp, and Storm.
When Rachel Carson wrote Silent Spring maximum permissible
levels of pesticide residues in food were called tolerances. These
limits were set by the federal government and regulated on an
individual basis: each food item was assigned a separate tolerance
level for each and every pesticide used in its production. Very
often, these assignments were based on inadequate knowledge of
the chemicals used, most of which were quite new to agriculture
at the time. Further research sometimes revealed that the health
risks from eating foods legally contaminated with these chemicals
were in fact more serious than initially presumed. These results
led to stepwise reductions of certain tolerances-and sometimes
to their revocation altogether.
Carson argued that this system was flawed from the start.
After-the-fact adjustments in tolerances exposed people for months
or years to levels of pesticides that were later admitted to be
unsafe. Furthermore, the whole concept of setting "safe"
limits for any one pesticide in any one food item was meaningless,
she asserted, because it did not take into account our total exposure
to multiple chemicals in multiple food items. Finally, enforcement
was woefully inadequate and underfunded: the federal government
had jurisdiction only over food moved across state lines and then
tested only a tiny fraction of these shipments for illegal residues.
She labeled as intolerable a regulatory methodology that involved
"deliberately poisoning our food, then policing the result."
Nevertheless, this was the food safety system in place when those
of us born in the first decades after World War II were infants
It is essentially still the same system. As of 1994, there
were 9,341 tolerances. The vast majority of these govern residues
on raw commodities; the remainder apply to residues known to concentrate
in processed foods. The EPA is now the federal agency responsible
for establishing these limits, while the Food and Drug Administration
(FDA) continues to be charged with enforcement. (The enforcement
responsibility for pesticide residue in meat and poultry, however,
rests with the USDA.)
In 1993, the National Research Council concluded that the
current regulatory arrangement permits pesticide levels in food
that are too high for children and infants. Tolerances are insufficiently
protective, according to the council's report, for two basic reasons.
First, they are not based solely or even primarily on health considerations.
The actual values chosen as legal limits reflect the results of
field trials designed to measure the highest residue concentrations
likely under normal agricultural practice.
Second, the safety margins supposedly ensured by tolerances
assume adult eating habits. However, children eat far fewer types
of food in proportionally greater quantities. A non-nursing infant
consumes fifteen times more pears than the average adult, for
example. And pears, as we have seen, are one of the most heavily
sprayed fruits on the market. Children also differ sharply in
their ability to activate, detoxify, and excrete contaminants.
Finally, childhood exposures to pesticides may lead to greater
risks of cancer and immune dysfunction than exposures later in
life. For all these reasons, the National Research Council in
1993 called for a new health-based approach to establishing tolerances
that would take into consideration the unique biology of children,
as well as their other non-dietary exposures to pesticides-including
air, dirt, carpets, lawns, and pets.
While baby food itself appears to have levels of pesticides
well below tolerance levels, detectable residues are nevertheless
found in all major brands sold in the United States. In one recent
study, researchers found traces of sixteen pesticides in eight
different baby foods purchased in U.S. grocery stores. Five of
these were possible human carcinogens.
Water is regulated much the same way food is. Just as food has
tolerances, drinking water has maximum contaminant levels. These
represent the highest limits allowable by law of particular toxic
substances in public water supplies.
In at least two respects, maximum contaminant levels for drinking
water are a more stringent measure than food tolerances(Recall
from Chapter Seven that)only a very tiny slice of all the food
shipped, sold, and consumed in the United States is actually tested
for contaminants. In contrast, all public drinking water is monitored
on a regular, ongoing basis. Furthermore, food tolerances govern
only pesticides, whereas maximum contaminant levels in drinking
water regulate pollutants from both industry and agriculture.
Like an accountant who proficiently measures and records individual
values but fails to sum the results, this system of regulating
contaminants in water suffers from the same constricted one-chemical-at-a-time
vision as the parallel system of regulating pesticide residues
in food. It ignores exposures to combinations of chemicals that
may act in concert. Radon gas and arsenic, for example, occur
naturally in some aquifers tapped for public drinking water. Both
are considered human carcinogens. Maximum contaminant levels have
been established for each, and each is supposed to be regulated
below those levels. However, if water containing these two elements
is also laced with traces of herbicides, dry-cleaning fluids,
and industrial solvents- even at concentrations well below their
respective legal limits-the resulting mixture may well pose hazards
not recognized by a laundry list of individual exposure limits.
Exposure to one compound may decrease the body's ability to detoxify
another, for example.
In other ways, maximum contaminant levels are a more lenient
standard than tolerances. For one thing, there are far fewer of
them. As of 1996, enforceable limits had been established for
a mere eighty-four contaminants. Indeed, some pesticides strictly
regulated in food are not regulated at all in drinking water.
For example, no maximum contaminant level exists for the herbicide
cyanazine, even though it has been registered since 1971 and even
though concerns about its carcinogenic properties recently prompted
a phaseout of its use. Cyanazine has been detected in wells in
fourteen different states and in rivers and streams throughout
the Corn Belt. In some Illinois drinking-water supplies, cyanazine
detections continue to exceed health-based advisory limits. But
because no enforceable standard exists, these detections do not
constitute violations of the law. In 1991, the National Research
Council expressed official concern about water contaminants without
legal limits: "The absence of evidence of their risk is solely
the result of the failure to conduct research; it should not be
misconstrued that [unregulated pollutants] are without risk."
To the question, then, of whether drinking water is regulated
on the basis of sound scientific knowledge, the answer is no.
Perhaps most revealing of all is the fact that regulation for
some contaminants is based on the annual average of four quarterly
measurements. In other words, drinking-water standards are violated
only when the yearly mean concentration of said contaminant exceeds
its maximum contaminant limit. A one-time transgression does not
automatically create a violation.
However imperfect, the current system of monitoring and regulating
drinking water does provide crucial information unavailable before
this decade. A younger sibling of the Clean Water Act, the federal
Safe Drinking Water Act became law in 1974 and brought all community
water systems under federal and state regulation. It required
the EPA to set legal limits for contaminants and placed the states
in charge of enforcing these limits. Maximum contaminant levels
for most organic chemicals were established only with the amendments
of 1986, and maximum contaminant levels for many common insecticides
and herbicides were promulgated as recently as 1991. To its credit,
Illinois was the first state to comply with these new regulations
and began routine monitoring of farm chemicals in drinking water
in 1992. Illinoisans thus have a more complete chronicle of water
contamination than do residents in many other states.
While it is shocking to contemplate how many decades have
passed between the widespread introduction of synthetic organic
chemicals into the environment and the decision to quantify their
presence in the water we drink, the data now available to us are
valuable in the most intimate way: compliance monitoring data
of finished drinking water describe the actual contaminants to
which we are exposed whenever we turn on the faucet.
Exposure to waterborne carcinogens is more commonplace than many
people realize. In the same way that intake of airborne pollution
involves the food we eat as well as the air we breathe, intake
of contaminants carried by tap water involves breathing and skin
absorption as well as drinking. These alternative routes are especially
important for the class of synthetic contaminants called volatile
organics- carbon-based compounds that vaporize more readily than
water. The solvent tetrachloroethylene is a common one. Most are
... volatile organic compounds combine with nitrogen oxides
to create poisonous groundlevel ozone, a major air contaminant.
As a contaminant of tap water, they present additional dangers.
Volatile organics are easily absorbed across human skin and enter
our breathing space when they evaporate. The higher the water
temperature, the greater the rate of evaporation. Humidifiers,
dishwashers, and washing machines all transform volatile waterborne
contaminants into airborne ones, as does cooking. These sources
of exposure are thought to be particularly worrisome for infants
and women home all day engaged in housework.
The simple, relaxing act of taking a bath turns out to be
a significant route of exposure to volatile organics. In a 1996
study, the exhaled breath of people who had recently showered
contained elevated levels of volatile organic compounds. In fact,
a ten-minute shower or a thirty-minute bath contributed a greater
internal dose of these volatile compounds than drinking half a
gallon of tap water. Showering in an enclosed stall appears to
contribute the greatest dose, probably because of the inhalation
... inhalation contributes more significantly to overall body
burden of volatile organic compounds than drinking-even when water
contamination is dramatic. Bottled water, by this accounting,
is not the answer.
Chlorination proved a cheap, effective means of halting waterborne
epidemics during World War I. By 1940, about 30 percent of community
drinking water in the United States was chlorinated, and at present,
about seven of every ten Americans drink chlorinated water.
Over the past two decades, nearly two dozen studies have emerged
that link chlorination of drinking water to bladder and rectal
cancers and, in some cases, to cancers of the kidney, stomach,
brain, and pancreas....
Chlorine gas is a noxious poison. However, the problem with
chlorinated drinking water does not lie with chlorine itself.
Rather, in a manner reminiscent of the way that air pollutants
combine in the atmosphere to create new chemical species, the
problem begins when elemental chlorine spontaneously reacts with
organic contaminants already present in water. Their organochlorine
offspring are known as disinfection by-products. Hundreds exist,
and several are classified as probable human carcinogens. Trihalomethanes,
a small subgroup of volatile disinfection by-products, are currently
receiving the most scientific and regulatory attention. Chloroform
is the most common one. As with any waterborne volatile compound,
our route of exposure to trihalomethanes is threefold: ingestion,
inhalation, and absorption. Indeed, trihalomethanes appear as
one of the major chemical culprits in ... bathing studies ...
One of the most ambitious ... investigations was led by Kenneth
Cantor himself. His research team personally interviewed nine
thousand people living in ten different areas of the United States.
Individual histories were then combined with water quality data
to create a lifetime profile of drinking-water use for each respondent.
In the final analysis,
bladder cancer risk increased with the amount of tap water
consumed, and this increase was strongly influenced by the duration
of living at residences served by chlorinated surface water....
There was no increase of risk with tap water consumption among
persons who had lived at places served by nonchlorinated ground
water for most of their lives.
Giving people cancer in order to ensure them a water supply
safe from disease-causing microbes is not necessary. Part of the
solution lies in making wider use of alternative disinfection
strategies. These include granular activated charcoal (which binds
with contaminants and removes them) and ozonaaon (which bubbles
ozone gas through raw water to kill microorganisms). Both techniques
have been used successfully in many U.S. and European communities.
... environmental research indicated that trash incinerators routinely
release troubling amounts of toxic and carcinogenic pollutants,
including the most potent of all the organochlorines: dioxin.
In addition, several new studies had demonstrated that dioxin
is harmful at far lower exposures than anyone ever suspected.
Even at a few parts per trillion, dioxan is capable, it seems,
of profoundly altering biological processes.
Also in the fall of 1994, the EPA released a three-thousand-page
draft reassessment of dioxin and was now soliciting public commentary
and reaction. Three years in the making, the study reaffirmed
dioxin's classification as a probable human carcinogen. The draft
report also announced three other findings. First, dioxan's effects
on the immune system, reproduction, and infant development are
much more significant than previously thought. Second, there is
no safe dose below which dioxin causes no biological effect. Third,
quantities of dioxan and dioxin-like chemicals present in most
people's bodies are already at or near levels shown to cause problems
in animals. Finally, the report identified incineration-of both
medical waste and common household garbage-as the leading source
of dioxan emissions in the United States and food (meat, dairy,
and fish) as the immediate source of 95 percent of the dioxin
found in the bodies of the general population.
No matter how you look at it, scooping garbage into an oven and
setting it afire is an equally primitive alternative to digging
a hole in the ground and burying it. The former contaminates air;
the latter, groundwater.
The relative popularity of these two options has waxed and
waned over the decades. In 1960, about one-third of the nation's
trash was burned in incinerators. Because of serious air pollution,
these were later phased out in favor of landfills. In the 1980s,
incinerators, now sporting high-tech pollution-control devices
and designed to generate electricity, staged a comeback, their
promoters referring to them as "waste-to-energy" or
"resource recovery" plants.
No matter how improved or what they are called, incinerators
present two problems that landfills do not. First, incinerators
only transform garbage; they don't provide a final resting place
for it. There remains the question of where to put the ashes.
Second, these cavernous furnaces create, out of the ordinary garbage
they are stoked with, new species of toxic chemicals. In addition
to producing electricity, they generate hazardous waste.
... the process of burning concentrates into the ash whatever
hazardous materials are present in the original refuse. Heavy
metals, such as mercury, lead, and cadmium, for example, are not
destroyed by fire. Occurring as ingredients in household batteries,
lightbulbs, paints, dyes, and thermometers, they are absolutely
persistent. Air pollution control depends on the ability of an
incinerator's cooling chambers to condense these metals onto fine
particles, which are then caught in special filters.
Once again, the irony of trade-offs becomes readily apparent:
the less air pollution, the more toxic the ash. An incinerator
burning eighteen boxcars of trash per day, for example, produces
about ten truckloads of ashes per day. The trucks must then rumble
out onto the highways, hauling their poisonous cargo through all
kinds of weather. Once ensconced in special burying grounds, incinerator
ash, of course, presents a hazard to groundwater.
The second problem is more an issue of chemistry than of physics.
Somewhere between the furnace and the top of the stack, on the
papery surfaces of fly ash particles, in the crucible of heating
and cooling, carbon and chlorine atoms rearrange themselves to
create molecules of dioxins and their closely related organochlorine
allies, the furans.
Incineration is not the only source of dioxins and furans. They
| can also form spontaneously during the manufacture of certain
pesticides-especially phenoxy herbicides and chlorophenols-and
during the bleaching of paper products, for example. What all
three of these processes have in common is chlorine. Dioxin is
synthesized when certain types of organic matter are placed together
with chlorine in a reactive environment. Such conditions are created
by combinations as banal as newspapers plus plastic wrap plus
In the inferno of an incinerator, many common synthetic products
may serve as chlorine donors for the spontaneous generation of
dioxins and furans: paint thinners, pesticides, household cleaners.
A major source of chlorine is PVC (polyvinyl chloride), which
can take the form of discarded toys, appliances, shoes, or construction
However unselective, the conditions required for the formation
of dioxins and furans are largely limited to those created by
contemporary human activities. Compared to incineration of synthetic
materials, forest fires produce trivial amounts-and these traces
may represent the release of dioxin molecules from soil and vegetation
contaminated by previous aerial deposits rather than de novo synthesis.
Sediment cores show no extensive contamination with dioxins until
the 1920s and 1930s, corresponding to the advent of organochlorine
production. People living in industrialized nations have higher
dioxin body burdens than those living in unindustrialized areas.
We also carry far greater levels of dioxin in our tissues than
do 2,800-year-old human mummies or 400-year-old frozen Eskimos,
which scarcely have any.
Dioxins and furans are not the natural-born children of fire.
They are the unplanned, unwanted offspring of modern chlorine
Even the newest, fanciest incinerators send traces of dioxins
and furans into the air. These molecules cling to bits of dust
and sediment. As they move downwind, they sink back to earth or
are washed out with rain. Here they coat soil and vegetation-grass,
clover, corn, beans, hay, watermelons, whatever. These chemical
contaminants are then consumed by us directly or are first concentrated
in the flesh, milk, and eggs of farm animals. A number of European
studies have documented elevated levels of dioxin in the milk
of cows grazing in pastures near municipal incinerators, for example.
Thankfully, dioxin lacks a few of the nastier traits of other
organochlorines It tends not to migrate to groundwater and is
not very volatile. Water and air are not, therefore, major routes
of exposure for us. Dioxin does accumulate in river sediments
and in the bodies of fish, and it collects in soil. It is not,
however, easily absorbed by the roots of most crops. The main
problem for us comes when dioxin-contaminated particles are deposited
onto the leaves, stems, and flowers of crop and pasture plants,
thus initiating the ballooning process of biomagnification. Foraging
farm animals can also accumulate dioxin from ingesting soil directly.
Between 170 and 190 incinerators operate at any given time in
the United States. They handle about 17 percent of the nation's
trash. Any respectable recycling program would easily put them
all out of business.
Our Bodies, Inscribed
A sponge for oil-soluble chemicals, body fat is considered an
especially sensitive indicator of exposure to persistent environmental
contaminants. In Japan, researchers examined a variety of industrial
contaminants in preserved fat collected from men who had died
between 1928 and 1985. The highest concentrations of DDT, PCBs,
and chlordane were found in samples collected during their respective
periods of maximum production, import, and use. In a 1996 study
conducted in Mexico, researchers found that levels of DDT in living
human tissues varied predictably across geographic space: residue
levels in both abdominal fat and breast fat were highest in areas
of intense agriculture and in tropical regions where DDT was used
for malaria control.
Breast milk has a lexicon all its own. About 3 percent fat,
it contains high concentrations of fat-soluble contaminants. These
pollutants are carried by the blood into the breast from fat reserves
scattered throughout the body and probably including the breast
fat itself. Since 1951, surveys of human milk in the United States
have consistently shown contamination by an array of persistent,
chlorinated chemicals. The issue of insecticides in breast milk
received close attention from Rachel Carson in 1962. A dozen years
later, 99 percent of breast milk sampled in the United States
was also shown to contain PCBs. About one of every four of these
samples contained PCB concentrations exceeding the legal limit
(2.5 parts per million), above which level commercial formula
is pulled from the shelves. Or, to express this another way: by
1976, roughly 25 percent of all U.S breast milk was too contaminated
to be bottled and sold as a food commodity.
The cancer risks assumed by these mothers and their nursing
infants-now adults, some with children of their own-remain to
be seen. The possible relationship between carcinogens in breast
milk and breast cancer (or cancer in offspring) has not been systematically
A study of more than eight hundred nursing mothers in North
Carolina has uncovered three patterns that make this question
an urgent one. Researchers found that the concentration of organochlorine
chemicals in breast milk increased with the age of the mother,
increased with the amount of sport fish consumed, and decreased
dramatically over the course of lactation and with the number
of children nursed. The first trend indicates that our bodies
are still amassing fat-soluble contaminants faster than we can
eliminate them. The second attests to the ongoing contamination
of our rivers, streams, and lakes.
The third fact is the most ominous one. Organochlorine contaminants
are not easily expunged from our tissues. Their sharp decline
in concentration over the course of breast-feeding, therefore,
represents the movement of accumulated toxins from mother to child.
It signifies that during the intimate act of nursing, a burden
of public poisons-insect killers, electrical insulating fluids,
industrial solvents, and incinerator residues-is shifted from
one generation into the tiny bodies of the next.
Happily, concentrations of a few of the most pernicious contaminants
of breast milk are stabilizing or even beginning to drop. Long-term
monitoring of human milk in Germany, for example, showed slight
declines during the early 1990s in levels of dioxins, furans,
organochlorine pesticides, and PCBs. Similarly, pooled samples
of human milk archived in the Mothers' Milk Centre in Stockholm,
Sweden, show declines in many PCB and DDT metabolites from 1972
to 1992. These trends indicate that efforts to shut down known
sources of these chemicals are finally beginning to have an effect
on their respective body burdens.