The Problem with Plastics
By Bruce Fellman
In his undergraduate course on environmental politics and law, John Wargo, Ph.D. ’84, likes to issue a challenge to his nearly 200 students: go one week—just one week—without exposure to plastics. “No one can do it,” says Wargo, professor of environmental policy, political science and risk analysis at F&ES. A little red-faced, he admits, “and neither can I. Plastics are extraordinarily pervasive and really hard to escape from. They’ve crept into our lives in millions of ways.”
In his book, Green Intelligence: Creating Environments That Protect Human Health, which was published in August by Yale University Press, Wargo explores the health dangers wrought by some of the best-known chemicals, such as DDT, mercury and strontium-90, which have been released deliberately or inadvertently. Toward the end of the book, he also includes a lengthy chapter on plastics, calling their impact on our lives “the quiet revolution.”
There’s no doubt that products made from plastic have considerable benefits, from safe food storage and water delivery to increases in energy efficiency and durability. But Wargo, whose career has been dedicated to investigating the too-often-underappreciated effects of chemicals on women and children—work that helped inspire the Food Quality Protection Act of 1996—shows that a significant element of disquiet has crept into that revolution. From birth to death, almost all of us now carry molecules that started off in plastics but wound up, via a number of routes, inside our bodies. And despite the long-standing insistence by the chemical industry and federal watchdogs, such as the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA), that these substances pose no risks to human health, a growing number of scientists, along with several legislators and a wide array of environmental organizations, now insist otherwise.
Wargo likens the situation to another “uncontrolled experiment”—our typically unwitting exposure to pesticide residues. In both, he says, “we’re playing with fire.”
The molecules of concern in the plastics story are known as endocrine-disrupting chemicals (EDCs), and the two most-studied sources of EDCs are bisphenol A (BPA), a basic building block of hard, polycarbonate plastics and epoxy resins, and phthalates (pronounced thal-ates), which are added to plastics to make them more pliable. Neither, at exposure levels currently considered safe by the EPA—50 micrograms per kilogram per day for BPA; 20 micrograms per kilogram per day for a phthalate called DEHP—are toxic or mutagenic. (Both are currently under federal review.) But in numerous animal studies, EDCs, at concentrations well below that safety zone, have proven all too capable of playing hob with hormones like estrogen, testosterone and others that have a crucial role in orchestrating normal development. There is also now abundant research that links BPA and phthalate exposure to such human health concerns as deformities of the male and female genitals; premature puberty in females; decreased sperm quality; and increases in breast and prostate cancers, infertility, miscarriages, obesity, type 2 diabetes, allergies and neurological problems, like attention deficit hyperactivity disorder.
To be sure, in a situation reminiscent of the early days of the tobacco and health debate, there’s no smoking gun—no accepted cause-and-effect mechanism. “But the absence of that kind of evidence is not the absence of risk,” says Wargo.
How much risk—and how to minimize it—is an open and highly controversial question that encompasses everything from the most fundamental biological research to legislative initiatives aimed at changing the basic assumptions underlying modern environmental regulations, the Toxic Substances Control Act, in particular.
One thing is certain: these substances are ubiquitous in the products we’ve come to know and love—and in us. In a well-publicized 2005 study by Antonia Calafat, a chemistry researcher at the Centers for Disease Control and Prevention’s National Center for Environmental Health, BPA turned up in nearly 93 percent of the urine samples her team analyzed. Calafat and other scientists have found similar results in subsequent studies; the story is the same for phthalates.
The chemicals enter our bodies primari-ly through food and drink. BPA, for example, not only is a common component of hard plastic containers, such as baby bottles and sports drink jugs, it also lines most of the cans we buy—cans that hold everything from vegetables and baked beans to beer and infant formula. Over time, particularly when the container is heated or scratched, BPA can leach out and wind up inside our bodies. Phthalates—there are many different kinds, but the best-studied isdiethylhexyl phthalate, or DEHP, for short—also enter our bodies by the food route, often when what we intend to eat picks up the molecules from contact with soft-plastic container walls or processing equipment, including the gloves that food workers use. But these ubiquitous “plasticizers” have other ways of insinuating themselves into our bodies. Until recently, DEHP and other phthalates were a key component of baby bottle nipples and soft plastic toys, including rubber duckies. (DEHP and several other phthalates were the subject of a temporary federal ban initiated last year that prohibited the sale of children’s toys and child care and feeding equipment containing the substances.) However, phthalates are also commonly found in cosmetics, medical equipment (such as catheter tubing, blood bags and other items found in places like hospital neonatal intensive care units), time-release medications, wood finishes, air fresheners and perfumes—that new car smell among them.
Guilty Until Proven Innocent
Worldwide production of BPA exceeds 6 billion pounds per year; about a billion pounds of phthalates are produced annually. These molecules are an external and, clearly, an internal fact of life, and over the past decade there’s been a rapidly increasing amount of research on the effects that plastics might be having on human health, particularly that of the unborn and infants—the most vulnerable among us. “There are at least several hundred studies that show worrisome problems,” says Wargo. “The quality of evidence about the risk of health effects is such that the EPA would not be allowed under current law to register BPA as a pesticide.” This year alone, three august scientific journals—Environmental Research; Philosophical Transactions of the Royal Society B: Biological Sciences; and Molecular and Cellular Endocrinology—devoted entire special issues to reviews of the latest EDC science. And on June 29, the Endocrine Society, the 14,000-member professional organization for basic and clinical researchers, took an unprecedented step in its nearly 100-year-old history, when it issued policy and scientific statements on EDCs that call for fundamental change in the way these chemicals are regulated. Acknowledging gaps in the understanding of EDC effects, the society nevertheless proposed that “until such time as conclusive scientific evidence exists to either prove or disprove harmful effects of substances, a precautionary approach should be taken in the formulation of EDC policy.”
In other words, says Wargo, a national plastics policy with a “first, do no harm” foundation would be prudent. “We need to get untested products out of the marketplace,” he says. Not surprisingly, Steven Hentges, the executive director of the polycarbonate/BPA global group at the American Chemistry Council, the industry’s trade organization, disagrees. Hentges characterized the research as an “enormous, confusing database” in which the only consistency is a “lack of effect” on human health. “BPA has been around for more than 50 years, but I’ve not seen anything in the science that would make us shift our views on its safety,” he says.
Regulatory agencies in this country, as well as those of the European Union, several individual European countries, Japan, Australia, New Zealand and, most recently, California, would agree with Hentges. Indeed, a statement issued in February 2008 by the FDA concluded that “the current levels of exposure to BPA through food packaging do not pose an immediate health risk to the general population, including infants and children.”
But more recently, prompted perhaps by a highly contentious investigation last year by the U.S. House of Representatives’ Energy and Commerce Committee about BPA safety and alleged industry-FDA collusion, the FDA began to backtrack.
The agency had already been stung by a September 2008 report, issued a month after the FDA had given BPA another clean bill of health, from the National Toxicology Program (NTP) that said, essentially, “Wait a minute.” Scientists at the NTP, which is part of the National Institutes of Health, reviewed the existing evidence and found that while there were “many conflicting findings” and a “number of remaining uncertainties,” there was “some concern”—the midpoint in the NTP’s five-level scale—that BPA exposure, at levels currently measured in the human population, could affect “the brain, behavior and prostate gland in fetuses, infants, and children.” (The NTP had fewer concerns, but not none, about BPA’s ability to bring about abnormal breast development, premature puberty in girls, birth defects and reproduction problems in adults.)
In October of that year, the FDA’s own science board questioned the adequacy of the parent agency’s earlier review, and last June FDA commissioner Margaret Hamburg told a House hearing on the Food Safety Enhancement Act that the agency was undertaking a new safety assessment; it is expected to be completed by the end of November.
Other governments around the world have already acted. Last year, Health Canada, that country’s health assessment organization, issued a ban, effective next year, on BPA-containing baby bottles. But in announcing the action, health minister Tony Clement termed it “precautionary” and said that “although our science tells us that exposure levels of newborns and infants are below the levels that cause effects, it is better to be safe than sorry.”
Minnesota and Connecticut, along with Chicago and Suffolk County in New York, have adopted similar bans. A number of companies, including retail giant Walmart and baby bottle manufacturers such as Avent, Playtex and Gerber, are opting to purge the molecule from products aimed at the under-3 set.
With phthalates, there’s a similar movement toward avoidance and, in some quarters, an outright ban. But again, this is based, according to published statements, more on precaution than on traditional toxicology. No one is suggesting that BPA and phthalates, at the minuscule levels in which they’re found in the human body, are either outright poisons or mutagens.
But that doesn’t mean, say scientists such as R. Thomas Zoeller, a developmental endocrinologist at the University of Massachusetts, that low-level exposures are without effect. “We have a huge potential problem here, and it’s one that our regulatory agencies are not prepared to handle,” says Zoeller. “Exposure, particularly early in life, to chemicals such as BPA and phthalates can result in a predisposition to disease and morbidity. This is, or should be, a significant cause for concern.”
As endocrine disruptors, BPA and phthalates belong to an array of molecules that either mimic or block the actions of hormones in the body. BPA is a synthetic estrogen that was first synthesized in 1891, and by the 1930s it and a close relative, diethylstilbestrol (DES), were being investigated as medications that could enhance estrogen levels and, so the theory went, help prevent miscarriages and other problems in pregnancy. DES proved the more potent of the two and was developed into a drug that was prescribed to as many as 10 million women until 1971. By then, studies had shown not only that the medication didn’t do the job, but that the daughters born to mothers who had taken DES during pregnancy were at greatly increased risk of developing clear cell adenocarcinoma, a rare form of vaginal cancer.
BPA, of course, was never designed to be deliberately ingested, but in the plastics boom that followed World War II—and well before the advent of the Clean Water Act in the 1970s—an untold amount of the material and the industrial waste products that went into manufacturing it were dumped into rivers and lakes. BPA con-tinues to enter the natural environment in sewage treatment effluent, including the BPA metabolites that we excrete, and in what leaches from landfills. Plastics dumped into the water—a garbage patch the size of Texas, much of it BPA-containing plastic junk, currently floats in the Pacific—also contribute to the environmental contamination; bacteria degrade the material into its component molecules, which can, sooner or later, enter the wildlife and human food chain.
Environmentalists started voicing concern about the impact of plastic pollution on the natural world in the early 1970s, and in 1993 biologists Theo Colborn, Frederick vom Saal and Ana Soto, synthesizing a growing body of disturbing research, first publicized the term endocrine-disrupting chemicals to describe what BPA, phthalates, pesticides (including DDT) and other industrial substances, such as dioxins and PCBs, might be doing to a wide variety of animals.
The endocrine-disrupting effects, the authors wrote in Environmental Health Perspectives in a seminal article that set the agenda for future research, “may be manifested in an entirely different way, and with permanent consequences, in the early embryo, fetus, and neonate from effects as a result of exposure only in adulthood; can change the course of development and potential of offspring, with the outcome depending on the specific developmental period(s) of exposure; and are often delayed and thus may not be fully or obviously expressed until the offspring reaches maturity or even middle age, even though critical exposure occurred during early embryonic, fetal, or neonatal life.”
The Colborn group study and a 1996 book on endocrine disruptors, Our Stolen Future: Are We Threatening Our Fertility, Intelligence, and Survival?—A Scientific Detective Story, by Colborn, Dianne Dumanoski and John Peterson Myers garnered headlines. Widespread concern about the possible effects of these chemicals on human health also helped build public support for the passage of the 1996 Food Quality Protection Act, legislation that mandated the creation of the EPA’s Endocrine Disruptor Screening Program. (That effort, after years of delays and false starts, is just now evaluating its first set of chemicals. Five phthalates, but neither DEHP nor BPA, will be screened in the initial group.)
But right from the beginning there was a scientific problem in the endocrine disruptor argument. BPA, as became apparent when it was initially tested for potency in the 1930s, is a weak estrogen; to have any kind of demonstrable effect, the concentrations of the stuff in the body and the environment would have had to have been many times what scientists were seeing. So, out of sight, out of mind—or so went conventional regulatory wisdom.
“The EPA limits are not safeguards at all,” says Wargo. For endocrine-disrupting chemicals answer to a different set of principles than do ordinary toxins, and as has been shown over and over in a welter of recent studies, these hormone mimics
can be most powerful at parts-per-billion, even parts-per-trillion, concentrations—infinitesimal levels well below the current regulatory radar, but levels, say scientists, that most of us now experience throughout our lives. New work has also uncovered the existence of previously unknown and exquisitely sensitive hormone receptors through which EDCs can work their mischief.
“There are many ways that chemicals at very low doses can produce slight alterations in endocrine signaling,” says endocrinologist Zoeller, “and it doesn’t take much, if you’re early in development, to cause long-term problems.”
Male Babies Less Male
One focus of Zoeller’s research is how thyroid hormone controls what are called cell fate specifications. “Undifferentiated cells in the fetal brain have to make decisions about what they want to be when they grow up. Thyroid hormone helps them make the right choice,” says Zoeller. “But interfere with the thyroid signal and cells start to make the wrong decision. That’s irrevocable.”
In animal studies with rats, Zoeller has shown that low levels of BPA are quite capable of disrupting fetal brain development, a situation that could lead to “a mosaic of effects,” which he’s currently attempting to document. And he’s hardly alone in demonstrating BPA’s ability to interfere with hormone signaling in animal experiments.
Yale School of Medicine reproductive biologist Hugh Taylor studies what are known as HOX genes, particularly a suite of them essential for normal uterine development and fertility. In an ongoing series of investigations, Taylor has exposed pregnant mice and their fetuses to DES and BPA and gotten similar results: females whose reproductive systems will not function correctly when they reach adulthood. “There’s a crucial, vulnerable time period during development,” says Taylor. “These endocrine disruptors change the fine tuning of the entire program, and then the effects are locked in for life.”
Phthalates seem to work in a similar manner, except they target the male set of hormones known as androgens. “The default developmental plan is actually female,” says Shanna Swan, an epidemiolo-gist at the University of Rochester School of Medicine and Dentistry. “The movement toward becoming male is controlled by testosterone during what we call the fetal programming window. Phthalates, like DEHP, can compromise the whole cascade toward masculinization.”
In “Environmental Phthalate Exposure in Relation to Reproductive Outcomes and Other Health Endpoints in Humans,” a paper published last year in Environmental Research, Swan showed that male babies born to mothers with relatively high concentrations of several phthalates in urine samples were, in fact, less male, according to a measure long used to gauge sexual dimorphism in rodents but only recently used for humans. This standard is called the anogenital distance, and it turns out that the distance in females is normally about half that of males. However, in Swan’s study, which builds on groundbreaking work that she and her team published in Environmental Health Perspectives in 2005 and 2006, the greater the concentration of phthalates in the mothers, the shorter the anogenital distance in their male offspring. Girls, as was predicted from rodent data, were not affected—by this measure, at least. The more phthalate-exposed boys also had narrower penises, compared to male infants whose mothers had lower levels of phthalates, and a greater propensity to have undescended testicles. It’s too early to tell whether these infants will also have, later in life, a lower sperm count, a higher incidence of testicular cancer and other hallmarks of what some researchers term “the phthalate syndrome.”
Swan admits that we can’t yet know what the long-lasting impact of exposure, if any, will be on these, or any other, boys. But she cautions against complacency. “So far, when we’ve made predictions from rodent studies, they’ve been borne out in humans,” she says. “And the prediction from rodent studies is that exposure does matter—and should affect male sperm count and fertility.”
In the mid-1980s, British epidemiologist David Barker proposed that the pattern of heart disease he was seeing in England actually had its roots in the womb. However, the problem was not simply bad genes; rather, it was the environment in which the fetus developed and the mother’s diet, in particular.
The “fetal origins of adult disease” hypothesis was initially dismissed as ridiculous, but there’s growing evidence to support it, says Soto, a Tufts University developmental biologist and one of the pioneers in studying the health effects of EDCs. “Many of the bad health trends we’re now seeing, from infertility to cancer, can be correlated with early exposure to BPA and other endocrine disruptors at levels that fetuses and infants experience every day,” says Soto.
Correlation, of course, does not imply causation—you learn that in statistics 101. But sometimes the public and their congressional representatives don’t make that distinction, especially when they see an increasing number of studies that seem to explain the pattern of many of the disturbing disease trends of the 21st century.
Calls For Regulatory Reform
The result is an odd kind of convergence, as ordinary citizens, watchdogs like the Environmental Working Group and the Environmental Defense Fund, members of Congress and even the American Chemistry Council itself are together calling for regulatory reform, particularly the Toxic Substances Control Act (TSCA). That landmark legislation, signed into law in 1976, was designed, said then-EPA administrator Russell Train, as “preventive medicine” that would “give public health far more of the weight that it deserves in the decisions by which chemicals are commercially made and marketed, by which they enter and spread throughout the human environment.”
The intent of Congress was “visionary,” says Michael Wilson, a research scientist at the University of California, Berkeley, Center for Occupational and Environmental Health. “But the law is widely thought to have failed.”
Of the 82,000 chemicals originally placed in the TSCA portfolio, 62,000—BPA included—were grandfathered, or “assumed to be safe until proven otherwise by the EPA,” says Wilson. But in a 1994 review of the law’s progress to date, the Government Accountability Office noted that although EPA scientists had identified 14,000 chemicals or chemical groups that they felt should be of concern to public and environmental health, the agency had taken action against only five: PCBs, asbestos, chlorofluorocarbons, dioxin and hexavalent chromium. According to Government Accountability Office reports in 2006 and earlier this year, the situation has not changed much. “We can certainly do better,” says Wilson.
Michael Walls, an American Chemistry Council vice president who has butted heads with Wilson in congressional and state hearings, actually has come to agree with him on the need for genuine regulatory reform. “There’s a clear lack of public confidence in the TSCA,” says Walls, adding that his industry is none too pleased with the law either.
On August 4, the American Chemistry Council issued a detailed manifesto that, in 10 steps, laid out a substantive agenda for TSCA reform. Among its planks is one calling for special consideration of the risks chemicals might pose to children and, in the words of the document, “whether an extra margin of safety is needed to protect” them. “We are committed to protecting children,” says Walls, pointing out the council’s sponsorship of the upcoming federally directed National Children’s Study, which will examine the effects of environmental influences, including manmade chemicals, on the health and development of 100,000 kids, from before birth until the age of 21, across the United States.
The manifesto appeared on the same day that a coalition of environmental groups called Safer Chemicals, Healthy Families published its own nine-point platform of TSCA reforms. And while there are points of disagreement between the two, even so harsh an industry critic as Richard Denison, a senior scientist at the Environmental Defense Fund, a coalition member, called the industry document “good and welcome news. The American Chemistry Council has come a long way, baby.”
A cynic might suggest that industry’s newfound approval of regulatory reform is simply a ploy to head off tougher measures, such as the Kid-Safe Chemicals Act, a proposal pending in Congress whose provisions Walls finds unacceptable. And there is nagging concern among some in industry that, unless something substantive is done on the regulatory front, legislators might even choose to adopt the tenets of the European Union’s wide-ranging Registration, Evaluation, Authorisation and Restriction of Chemical Substances law. REACH, adopted in 2007, embraces the “precautionary principle” and calls for each of the 30,000 chemicals in use in Europe to be evaluated for safety.
And then, of course, there is the burgeoning movement toward “green chemistry,” a term coined by Paul Anastas, Teresa and H. John Heinz III Professor in the Practice of Chemistry for the Environment at F&ES, when he headed the EPA’s Industrial Chemistry Branch. Anastas, who is awaiting confirmation as President Obama’s choice to lead the EPA’s Office of Research and Development, defined the field this way: “Green chemistry is the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture and application of chemical products.”
The definition appeared in Green Chemistry: Theory and Practice, the 1998 textbook co-written by Anastas and chemist John Warner, which set the ground rules for the field. Warner now heads the Warner Babcock Institute for Green Chemistry, which is in the business of finding environmentally friendlier alternatives to current chemicals and processes. So far, he and his team have come up with a more efficient way to deliver medications that ensures that less of them go into the environment, as well as a cleaner solvent for working with silicon wafers and a nontoxic hair coloring system.
“There are lots of alternatives for certain applications,” says Warner.
For example, in the late 1990s, can manufacturers in Japan responded to consumer concerns by coming up with both a BPA-free liner material and a process that prevents most of the BPA from leaching. Kaiser Permanente, the nonprofit health care system, pushed its suppliers to find a replacement for DEHP and other potential problematic plastics. And in a survey that Warner conducted with his students when he was teaching at the University of Massachusetts at Lowell, he discovered that about half the merchants in the area were no longer issuing cash register and credit card receipts made from a carbonless material that contained BPA. These receipts, he feels, can be a significant source of exposure to the chemical “and, clearly, one that’s absolutely unnecessary.”
What’s holding up progress on the green chemistry front, says Warner, is a combination of industrial inertia, regulatory uncertainty and, in many cases, the lack of a good alternative.
“There are many steps involved in the manufacturing process, and if you have to, say, come up with four or five replacements, not just one, then the economics stink,” he says. “And in a world where we’re focused only on the next quarter’s profits, who can afford to take the risk? This is where government has to step in.”
Federal funding for basic research into greener alternatives is crucial, as is regulatory reform that provides the public with information about the chemical nature of plastics in our lives and rules tough enough to protect us from the new kinds of endocrinological harms that are of increasing concern. At the same time, he cautions, any new regulations should seek to “avoid stifling innovation by scaring away the very people who are trying to do the right thing.”
Warner is a member of this vanguard. “I’m convinced the future is green, and while I don’t know how long it’ll take to get there, I think we’re on the right trajectory,” he says.
To get there, says Wargo of F&ES, “We need a national plastics policy that makes sense. This will require regulatory institutions that are independent and transparent, as well as an increase in what I call ‘green intelligence.’ We live in a vacuum of information, and a product labeling system that is simply a list of 40-letter-long chemicals is not good enough. Most people don’t have a clue about their exposure levels, and the fault lies with government and industry. In my book, my objective is to make readers aware of where these generally invisible dangers are now—and how they can be avoided.”
Meanwhile, BPA and phthalates continue to circulate in the environment and in our bloodstreams, from the moment of conception to the end of our hopefully-not-endocrine-disrupted lives. “On the regulatory side, we’re in a hole, and it’ll take us a long time to dig ourselves out,” says Wargo. “Until that happens, it’s like the Wild West. The public bears the risks of exposure, and the public has to decide how to avoid them.”
At the end of his book, Green Intelligence, Wargo offers many ways to minimize exposure (see sidebar at right). But, in a lesson that shows just how hard this is to achieve in modern life, one day his well failed. In watching the repair, he noticed the metal tank in which the water was stored and pressurized before it went into the pipes and ultimately into his tap water. The tank, he discovered, was lined with BPA, which prevents corrosion. Finding a BPA-free replacement was difficult, so he left well enough, or what Wargo, like many of us, hoped was well enough, alone.