Animals, Earth, Air, Water,
Our Bodies Inscribed

excerpted from the book

Living Downstream

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 human carcinogen.

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 and children.

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 suspected carcinogens.

... 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 of steam.

... 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 fire.

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 debris.

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 chemistry.

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 investigated.

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.

Living Downstream

Environment watch

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