The Problem with Plastics
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.