Carcinogenic flame retardants were supposed to be gone by now, but, like endocrine-disrupting plasticizers, they persist
A dangerous flame retardant known as "Tris" has reappeared in products designed for babies and young children, among them car seats, changing table pads, portable crib mattresses, high chair seats, and nursing pillows. (Tris, once used in children's sleepwear, was removed from these products in the 1970s, after it was identified as a carcinogen and a mutagen, a compound that causes genetic mutation.) Also found in these products, according to the same recent study, which appeared in Environmental Science & Technology, is another flame retardant, pentaBDE. This compound was banned in Europe in 2004, when its U.S. manufacturers voluntarily discontinued it after it was found to be environmentally persistent, bioaccumulative, and to adversely affect thyroid function and neurological development.
The study also identified new compounds whose ingredients include some of the older toxic substances—and it found all of these and other flame retardants in 80 percent of the 101 infant and children's products tested. That these chemicals, associated with adverse health impacts including cancer and endocrine disruption, are so widespread raises serious questions about the U.S. system of chemicals management and how we evaluate product safety.
With the potential health hazards of widely used synthetic chemicals coming under increasing scrutiny, and with a growing call from medical and scientific professionals for policies that protect children from such hazards, the question of what takes the place of a threatening chemical has become increasingly important. It also prompts questions about whether it is better to substitute another chemical for the one posing problems or to redesign a product so it can achieve its desired performance, perhaps without such chemicals.
The brominated and chlorinated flame retardants (BFRs and CFRs) found in these children's products offer one cautionary example. Another group of chemicals known as phthalates, used to increase the flexibility of one of the world's most widely used plastics, polyvinyl chloride (PVC), offers another. Together, these compounds account for the vast majority of all plastics additives used worldwide.
In the case of the flame retardants used in upholstery foams, carpet backings, textiles, and hard plastic appliances and other products since the 1970s, new compounds introduced to replace the hazardous ones have in fact resembled their predecessors. The result, despite "early warnings and periodic reminders about the problematic properties of these chemicals" is a "continuing pattern of unfortunate substitution," wrote Linda Birnbaum, director of the National Institute of Environmental Health Sciences and National Toxicology Program, and Ake Bergman, professor of environmental chemistry at Stockholm University, in Environmental Health Perspectives in October. They were introducing a statement of concern about BFRs and CFRs signed by nearly 150 scientists from 22 countries.
While cushions and electronics can function without flame retardants, PVC cannot work without plasticizers. Phthalates—oily, colorless liquids based on benzene chemistry—have been the plasticizers of choice since PVC was commercialized in the early 20th century. Without phthalates, PVC would be brittle and of limited use. In some bendable PVC products, phthalates can make up as much as 40 to 50 percent of the finished plastic—and in 2008, nearly 540 billion pounds of PVC were produced worldwide.
Phthalates are also used in other vinyl-based products, to create thin and flexible films (they've been used in nail polish and other cosmetics), as lubricants (hence their use in lotions), as solvents, and to extend the life of fragrances, among many other applications. They are found in everything from food packaging to insect repellant to bath and teething toys. Some phthalates have been shown in animal studies to cause birth defects, and a number of popular phthalates have been identified as endocrine disrupters that interfere with male reproductive development. Concerned, Europe restricted use of about half a dozen phthalates in 2008, and the U.S. restricted them in products intended for use by children under age 12. Similar regulations exist elsewhere, including Canada, Japan, and Taiwan. On May 4, the French National assembly voted to ban phthalates altogether, based on concerns about endocrine disruption.
Like the BFR and CFR flame retardants, phthalates are released from the materials to which they're added. That phthalates could migrate from PVC has been known since the 1960s, when the Air Force found that this could cause problems on spacecraft and phthalates were detected leeching from plastic tubing used in blood transfusion and dairy equipment. We can take phthalates into our bodies by breathing them, ingesting them, and by absorbing them through our skin. A study published in March of this year found that when people eliminated certain packaged foods from their diets, levels of the corresponding phthalates in their urine dropped by more than 50 percent.
So with growing concerns about phthalates and increasing restrictions on their use, a search is on for alternatives—ideally non-toxic compounds that will not migrate out of the plastics. But PVC itself, even without the phthalates, raises questions about product safety. While it may be possible to find a non-toxic plasticizer, vinyl chloride, the main ingredient of PVC, is a human carcinogen that also causes liver and nerve damage. PVC also poses hazards when burned, as incomplete combustion can result in dioxins, also carcinogenic compounds. In April, the Environmental Protection Agency proposed increasing emissions standards for plants that produce PVC, citing inhalation risks to people who live in communities where these manufacturing facilities are located. There are currently 17 such plants in the U.S., mostly in Louisiana and Texas.
Together these flame retardants and plasticizers raise profound questions about how we think about designing new materials and the wisdom—from an environmental health perspective—of regulating chemicals one at a time rather than by examining their characteristics and behavior. They also point to the need to look at a product's entire lifecycle when considering its health impacts. There are many arguments to be made about the costs and benefits of using these materials, and moving away from such widely and long-used materials presents many challenges. Yet as Paul Anastas and John Warner, often considered to be the founders of green chemistry, point out, there is no reason a molecule must be hazardous to perform a particular task. To solve the kinds of problems posed by materials like PVC, we need, as Anastas has said, "to design into our technologies the consequences to human health and the environment."
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