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  Sizewise, medicine is a small end market, consuming less than 10 percent of all polymers produced in the United States —peanuts compared to packaging (33 percent), consumer products (20 percent), and building and construction (17 percent). But it's a strong, recession-proof market and one that has provided the industry enormous PR value. Medicine has long been plastic's indisputable good-news story, the showcase of polymers' benefits. For one recent public relations campaign, the American Chemistry Council featured a photo of a newborn in a plastic incubator.

  Plastics are indispensable in neonatology, agreed Dr. Billie Short as we toured the fifty-four-bed NICU at Children's National, where preemies like Amy may spend the first several weeks or even months of their lives. Short is chief of neonatology at George Washington University, and as we stood by Amy's bedside, she described how plastics enable the care of infants this fragile. Reaching her hands through the pair of portholes in the sides of Amy's incubator, she pointed out the quartet of clear, exquisitely thin tubes that were delivering nourishment and medicines to Amy from the several plastic bags hanging on a nearby rig. One was inserted into a vein in her head to provide fluids; another, delivering antibiotics, tapped into a vein in her arm, which itself was scarcely wider than the pen I was using to take notes. Two catheters ran into the stump of her umbilical cord, one to feed nutrients into a vein and another connected to an artery so that the nurses could monitor Amy's fluctuating blood pressure and the levels of oxygen in her blood. A respiratory tube threaded down her throat was attached to a plastic-encased machine that helped her breathe. All the tubing was soft and supple enough to slide through her delicate body without tearing anything. Meanwhile, that enclosed plastic incubator maintained a carefully calibrated humidity and warmth (preemies like Amy don't have the layers of skin and fat needed to sustain body temperature). This kind of equipment is one of several factors that have helped raise the survival rates of premature babies over the past forty years.

  I watched her chest rise and fall as rapidly as a sparrow's. Every so often, an involuntary tremor would ripple across her tiny body, as if she were shuddering over whatever rude force in the universe had pulled her from the dark coziness of her mother's womb into this synthetic approximation.

  How long will she be hooked up to all this? I asked Short, indicating the intravenous tubing.

  "Oh, for weeks," said Short. After that, once she became stable enough, Amy would receive her nourishment through feeding tubes.

  Neonatology is a relatively new medical specialty. The first NICU was set up in 1965. That the field has blossomed in the age of polymers is probably not a coincidence, given the challenges of treating babies with hair-thin veins and tissue-paper skin. Still, until the 1980s, most of the intravenous fluids used in NICUs came in glass bottles. Short remembers the worry and inconvenience of those bottles falling and breaking. At first, said Short, the move to plastic seemed a tremendous advance. "We all thought plastics were inert, safe. We didn't have to worry about it. Then as the research came out, it became more and more evident we needed to pay attention."

  And here, Short hit on the central paradox of plastic in medicine: in the act of healing, it may also do harm. Research now suggests that the same bags and tubes that deliver medicines and nourishment to these most vulnerable children also deliver chemicals that could damage their health years from now. The vinyl plastic typically used in IV bags and tubing contains a softening chemical that can block production of testosterone and other hormones. This chemical, called a phthalate (pronounced tha-late), doesn't act the way familiar environmental villains such as mercury and asbestos do; for those substances, there's a direct connection between exposure and easily recognizable subsequent harm, such as cancer or a birth defect or death. Phthalates leave tracks along more complex, convoluted routes. That's because they play havoc with the body's endocrine system—the intricate, self-regulating choreography of hormones that dictate how an individual develops, reproduces, ages, fights disease, and even behaves. Phthalates are not the only chemicals used in common plastics that have disruptive effects. By mimicking or blocking or suppressing production of hormones such as testosterone and estrogen, these various chemicals may produce subtle, long-term effects that don't show up for years or appear only in our offspring. They may make us more vulnerable to asthma, diabetes, obesity, heart disease, infertility, and attention deficit disorder, to name just a few of the health problems that have been linked to various of these chemicals in animal studies and epidemiological surveys. And some of these substances may do their damage even at minute concentrations we never considered worrisome.

  Just as plastics changed the essential texture of modern life, so they are altering the basic chemistry of our bodies, betraying the trust we placed in them. All of us, even newborns, now carry traces in our systems of phthalates and other synthetic substances, such as fire retardants, stain repellants, solvents, metals, waterproofing agents, and bactericides. Though the chemicals surely don't belong there, the actual threats to human health are still uncertain. As different as my life is from baby Amy's, I can't help but see similarities. In the age of plastics, we are all incubator babies, inescapably tied to polymers, facing a world of new risks.

  Few objects speak to the medical impact of plastics—the benefits and the risks, and the complexities of balancing the two—as well as the plastic IV bag with its snakelike tubing.

  This staple of health care was introduced in the years following World War II by Carl Walter, a surgeon and professor at Harvard Medical School. Like many surgeons, Walter had a mechanical mind and a gift for invention. In the late 1940s, he turned that talent to the problems plaguing blood collection and storage. The whole idea of blood banking was still new. Walter himself had established one of the first blood banks just a decade before, locating it in an obscure basement room at Harvard to avoid arousing the ire of university trustees who considered it "unethical and immoral" to collect and use human blood. Blood banks of that era faced significant problems. Donors' blood was drawn through rubber tubes into rubber-stoppered glass bottles, a process that often damaged the red blood cells and allowed bacteria and air bubbles to get in. Searching for a better system, Walter hit upon the idea of using one of the most exciting of the new thermoplastics, polyvinyl chloride, better known as PVC, or vinyl.

  PVC is a unique polymer. Unlike other plastics, PVC has chlorine as one of its chief ingredients, a greenish gas that is derived from a salt (sodium chloride). To make PVC, the chlorine is mixed with hydrocarbons to form the monomer vinyl chloride, which is then poly­merized, resulting in a fine-grained white powder.

  This unusual chemistry is PVC's greatest strength, but also its greatest problem—the reason that industry sings its praises and that environmentalists call it Satan's resin. The chlorine base makes PVC chemically stable, fire resistant, waterproof, and cheap (since less oil or gas is needed to produce the molecule). It also makes PVC hazardous to manufacture and a nightmare to dispose of, because when incinerated it releases dioxins and furans, two of the most carcinogenic compounds in existence.

  PVC is also an unusually polyamorous molecule; it's amenable to hooking up with a host of other chemicals that can lend the resin an extraordinary array of properties. Indeed, without additives, PVC is so brittle that it is virtually useless. But combined with other chemicals, it can be "converted into an almost limitless range of applications," as its pitchman the Vinyl Institute boasted. It can be made into the stiff planks used to side houses, the strong pipes that carry water, the insulating coating of electrical wires, the squeezable arms of a doll, the soft drapes of a shower curtain, the fleshlike texture of a dildo. Such versatility has made PVC one of the top-selling plastics in the world and a frequent choice for makers of medical devices. But owing to the resin's dependence on additives, it has come under fire.

  The material that caught Carl Walter's eye was a particular variety of vinyl, known as plasticized PVC, in which the plastic is made soft and pliabl
e through the addition of a clear, oily liquid called di(2-ethylhexyl) phthalate, or DEHP, a member of the phthalate family. Phthalates have become so ubiquitous in consumer and industrial products that manufacturers make nearly half a billion pounds of them each year. They're used as plasticizers, lubricants, and solvents. You'll find phthalates in anything made of soft vinyl. But you'll find phthalates in other types of plastic and other materials too, in food packaging and food-processing equipment, in construction materials, clothing, household furnishings, wallpaper, toys, personal-care products such as cosmetics, shampoos, and perfumes; adhesives, insecticides, waxes, inks, varnishes, lacquers, coatings, and paints. They're even used in the time-release coating for medications and nutritional supplements. There are about twenty-five different types of phthalates, but only about half a dozen are widely used. Of those, DEHP is one of the most popular, especially for medical uses. And for that, we can thank Carl Walter.

  For Walter's purposes, plasticized PVC seemed ideal: it was durable, flexible, and, unlike glass, didn't seem to damage red blood cells. It permitted CO2 in the blood to dissipate and oxygen to disperse, which was also good for the blood cells. As far as he could tell, the material was completely inert. To persuade colleagues of its virtues, he brought a blood-filled bag to a meeting, dropped it on the floor, and then stepped on it. The bag held, which in itself was a huge advantage over breakable glass. But the real advance was that the bag could be connected to other bags to form a secure, sterile system through which blood could be separated into its various component parts—red blood cells, plasma, and platelets.

  The new technology revolutionized the way blood was collected and used. For the first time it was possible to safely separate and store blood components. Instead of giving a patient whole blood, a physician could administer only the parts a person needed. A single unit of blood could now be stretched to help three different people.

  The U.S. Army employed the new bags during the Korean War, and they proved a vastly safer and more reliable way to treat injured soldiers in the field. Medics could squeeze the bags to get the contents to flow faster. Glass bottles, on the other hand, worked by gravity alone; they had to be hoisted high above the patient, creating a target for enemy fire. By the mid-1960s, PVC blood bags were standard in civilian blood banks and hospitals. Walter's innovation also began rippling through the field of intravenous therapy. Over the decades, medical suppliers gradually swapped out glass for PVC to hold a wide range of fluids that were delivered intravenously, from saline to drugs to nutritional supplements.

  One of PVC's big selling points was its presumed chemical stability. As Modern Plastics pointed out in a 1951 article entitled "Why Doctors Are Using More Plastics": "any substance that comes in contact with human tissue ... must be chemically inert and non-toxic," as well as compatible with human tissue and not absorbable. PVC was one of the plastics that seemed to fit that bill. But in the late 1960s and early 1970s, a series of revelations began chipping away at that presumption of innocence.

  First, there was the discovery that vinyl chloride gas—the key chemical used to make PVC—was far more dangerous than had been supposed. Doctors at B. F. Goodrich's PVC plant in Louisville, Kentucky, discovered in 1964 that workers there were developing acroosteolysis, a systemic condition that caused skin lesions, circulatory problems, and deformation of finger bones. Then, in the early '70s, European researchers found evidence that vinyl chloride was carcinogenic. As David Rosner and Gerald Markowitz detailed in their expose' Deceit and Denial: The Deadly Politics of Industrial Pollution, the vinyl industry initially suppressed results of studies that showed that low levels of vinyl chloride caused liver cancer in rats. But the cover-up was revealed in 1974 when four workers at the Goodrich plant died from that same rare liver cancer, angiosarcoma. A writer for Rolling Stone likened the Louisville factory to "a plastic coffin."

  Frightening as the Louisville revelations were, they described a familiar environmental hazard, one stemming from dangerous workplace conditions and largely confined to the factory floor. If vinyl chloride caused cancer in PVC workers, then plant conditions would have to be changed so workers were no longer in danger. And indeed, after a contentious regulatory and legal battle, the newly formed Occupational Safety and Health Administration set a strict threshold that dramatically limited workers' exposure to the chemical. (The ruling dropped acceptable levels from five hundred parts per million to one part per million.) Industry howled, claiming that the cost of complying with the new standard would run as high as $90 billion, but in the end, making plants safer cost just a fraction of that, only $278 million. Since then, no cases of angiosarcoma have been reported among vinyl workers.

  While the vinyl chloride scandal was unfolding, another line of research was pointing to a more insidious—and also more uncertain—risk: that the chemicals added to PVC were leaching out of widely used products.

  Johns Hopkins University toxicologists Robert Rubin and Rudolph Jaeger stumbled onto that discovery during a 1969 experiment involving rat livers. The livers were being perfused with blood from PVC blood bags and tubes when it became apparent that some unknown compound was confounding the experiment. Rubin asked Jaeger, then his graduate student, to figure out what the mystery compound was. Jaeger discovered it was DEHP, the plasticizing chemical added to the vinyl that was used to make blood bags and tubing. As he would soon find, those bags could be as much as 40 percent DEHP by weight; the tubing could be as much as 80 percent. The additive is not atomically bonded to the molecular daisy chain that makes up PVC, which means it can migrate out, especially in the presence of blood or fatty substances.

  Neither Rubin nor Jaeger knew if DEHP was toxic, but they were surprised and a little alarmed by follow-up studies in which they found traces of the chemical in stored blood as well as in the tissues of people who had undergone blood transfusions. When Jaeger submitted their paper documenting those findings to the prestigious journal Science, the editor rejected it, telling him that unless the chemical was demonstrably toxic, it didn't really matter if it was getting into people. Jaeger boldly called the editor back and persuaded him to change his mind. As he recalled, "I said, 'Look at the extent to which phthalates and PVC plastic are used in society. It's worth publishing because scientists need to be informed about the ubiquitous nature of extracts from plastics.'"

  Not long after, a chemist at the National Heart and Lung Institute reported that he too had found residues of DEHP and other phthalates in blood samples taken from a sample population of one hundred people. But these were not people who had been exposed through work or who had undergone blood transfusions; they were simply consumers of plastic goods, folks who might have been exposed to phthalates from any of thousands of everyday products, from cars to toys, wallpaper to wiring. Reporting the findings in 1972, the Washington Post declared, "Humans are just a little plastic now."

  What, exactly, did it mean to be "just a little plastic"? At the time, the consensus was: not very much. Plastics manufacturers had long known that additives could and would leach out of polymers but maintained that people weren't exposed to high enough levels to suffer any harm. After taking a hard look at DEHP and other phthalates, mainly in adults, independent toxicologists came to much the same conclusion. They found that very high doses could cause birth defects in rodents and induce liver cancer in rats and mice, but only through a mechanism that rarely affects humans. When I called Rubin and Jaeger, each told me that after much study they had concluded there was no cause for concern. Rubin, now retired, said he spent years studying DEHP and turned up only one relevant hazard: an uncommon phenomenon that surfaced during the Vietnam War in which injured soldiers who were in shock died after receiving blood transfusions from vinyl blood bags. Under that rare set of circumstances, the chemical could trigger a lethal immune reaction in the lungs. Otherwise, Rubin said, he'd come to the conclusion that DEHP and other phthalates "were—how shall I put it?—as harmless as chicken soup."

  There we
re a few contrary voices at the time, but they mostly reflected a general sense of unease on the part of scientists who just weren't comfortable with the growing ubiquity of industrial chemicals and the intimate ways in which humans were coming into contact with them. It would take a sea change in the science of toxicology—and the late-life career change of a Colorado woman—before those voices would gain any kind of significant audience.

  One of the basic textbooks of toxicology, which came out in 1987, clearly articulates the theory of poison that has held sway for centuries. On [>] of A Textbook of Modern Toxicology, authors Ernest Hodgson and Patricia Levi declare that poison is "a quantitative concept. Almost any substance is harmful at some dose and, at the same time, is harmless at a very low dose." Hodgson and Levi use the example of aspirin: two tablets of aspirin are healing, twenty can cause an upset stomach, and sixty can be lethal. The dose makes the poison. This idea, first formulated by the medieval alchemist Paracelsus, has been one of the fundamental principles of modern toxicology.

  But the very same year that Hodgson and Levi published the first edition of their toxicology text, a zoologist named Theo Colborn began developing a different theory of toxic effects that would challenge that conventional wisdom. Colborn wasn't even a toxicologist by trade. She had spent years in Colorado raising four children and working as a rancher and a pharmacist when she started to worry that pollutants in local rivers and lakes were contributing to health problems in the area. She wanted to better understand water-quality issues, so at the age of fifty-one, she went back to school and got a master's in freshwater ecology and then a PhD in zoology. In the late 1980s, she landed a job at the Conservation Foundation in Washington, D.C., where her boss asked her to survey research on the effects of pollution in the Great Lakes. It was a potentially mind-numbing job of data crunching. Yet Colborn, as one reporter observed in a profile, had a talent for mining the glittering patterns hidden in piles of data.