BISPHENOL A INHIBITS BRAIN DEVELOPMENT–EVEN IN SMALL DOSES
It’s in plastic baby bottles, water jugs, dental sealants, food packaging, canned goods, cell phones, CDs and DVDs, and countless other household products. In 2005 alone, manufacturers worldwide produced approximately 3.5 million tons of the industrial chemical Bisphenol A—primarily for use in manufacturing polycarbonate (PC) plastic and epoxy resins. Although past studies have shown conflicting results, and some have deemed the chemical safe, new research adds to the evidence that Bisphenol A, or BPA, may pose a significant health threat.
Conducted at the University of Cincinnati, the research concluded that even low doses and short exposure to BPA can inhibit brain development. Published in Endocrinology, this latest study measured BPA’s effect on rats in stages of development equivalent to the third trimester through the first few years of human life (2005, vol. 146, no. 12). Experiments revealed that “surprisingly low” doses (0.23 parts per trillion) slowed neuron growth after only minutes of exposure. BPA acts as an artificial estrogen, potentially interfering with the hormone’s normal role in developing neurons.
Previous studies have linked BPA to reproductive problems, developmental disorders, and increased breast and prostate cancer cell growth. “The presence of large quantities of [BPA] in the environment may not only have long-lasting effects on human health but may also impact the well-being of a diverse array of ecosystems,” says Scott Belcher, PhD, an associate professor at UC College of Medicine and the study’s lead author. Given estrogen’s critical role in brain development, as well as in the normal functioning of adult brains, Belcher and his colleagues hope the findings will encourage regulatory agencies to reevaluate the chemical’s use more seriously, especially in materials that come into contact with foods.
By Julie Rothschild Levi
Food containers … water bottles … cling wrap … toys. We’re surrounded by plastics because they’re inexpensive and handy. But some scientists question their safety. Find out how plastics may affect you, the environment, and world communities. Peek inside any American household, and you’ll find it brimming with plastics. From food containers, cling wraps, and water jugs to baby bottles and toys, plastics are ubiquitous because they’re inexpensive, handy, and durable.
Yet many scientists and consumer advocates question the safety of plastics use. They argue that we’re trading health for convenience. Others say ignore the hype—plastics are perfectly safe. Although several types of plastics do appear to be safe, some have been shown to potentially affect health, such as PVC (or vinyl), found in some cling wraps and toys, and polycarbonate (PC), found in baby bottles and tin-can linings.
From an environmental perspective, noxious chemicals from plastics manufacturing contribute to water, air, and soil pollution, affecting not only ecosystems but human health as well, especially in China and Mexico. And Americans recycle just 5 percent of all plastics—leaving the rest to sit in landfills forever.
Although it may not be necessary (or realistic) to purge plastics from our lives, it may well be worthwhile to consider reducing their use, for the sake of our health and our world.
How Plastics Affect Your Health
“We’re reminded of the movie The Graduate, in which Dustin Hoffman was advised to go into plastics because it was the wave of the future,” says Walter Crinnion, ND, head of the Environmental Medicine Center of Excellence at the Southwest College of Naturopathic Medicine and Health Sciences in Tempe, Arizona. “But what’s happened is that plastics have gone into all of us.”
Sounds scary, but how concerned should you be? That depends on whom you trust.
Scientists don’t question the fact that chemicals migrate out of plastics. What they dispute is how it affects human health. “We’re regulating [plastics], so they’re safe,” says Edward Machuga, PhD, a consumer safety officer at the Food and Drug Administration (FDA) in Washington, D.C. Manufacturers of any new food-contact plastic must conduct extensive tests and submit data to the FDA. The FDA sets limits on the levels of chemicals that plastics can release into food for humans, based on “acceptable dietary intake” levels shown to be nontoxic in animal studies.
That’s not good enough anymore, says biologist Pete Myers, PhD, publisher of EnvironmentalHealthNews.org and coauthor of Our Stolen Future (Plume, 1997). “For decades the study of toxicology followed the paradigm that the dose makes the poison: High levels are bad, and low levels have no effect.” But, he says, traditional studies miss a whole class of very low-level effects that can upset the hormonal system’s natural balance.
The plastics to avoid, according to experts such as Myers, include PVC (recycle triangle number 3) and PC (recycle triangle number 7), which have been shown to leach out potentially hazardous chemicals. Of particular concern are phthalates, plasticizers added to many PVC products such as medical devices, toys, food wraps, cooking-oil bottles, and building products. A recent landmark study, conducted in part by the National Center for Environmental Health at the Centers for Disease Control and Prevention (CDC), detected seven common phthalates in the urine of all 289 subjects (Environmental Health Perspectives, 2000, vol. 108, no. 10). Such results support the contention that phthalate exposure is both higher and more common than previously thought, says Crinnion.
Fetuses, young children, and women of reproductive age seem to be most vulnerable to these chemicals’ effects. Phthalates have been found to be carcinogenic—and to cause fetal death, malformations, and reproductive toxicity—in laboratory animals (Pediatrics, 2003, vol. 111, no. 6). One recent study linked premature human births to maternal exposure to two phthalates, MEHP and DEHP, the most commonly used plasticizers (Environmental Health Perspectives, 2003, vol. 111, no. 14). Another showed that women with endometriosis had significantly higher-than-average DEHP concentrations in their blood (Human Reproduction, 2003, vol. 18, no. 7). And the CDC’s 2000 study found significantly higher levels of MBHP, a proven reproductive and developmental toxicant in rodents, in its female subjects of reproductive age (20 to 40 years old).
However, a conflicting recent study concluded that DEHP and DINP phthalates are “not likely” to cause cancer in humans (Critical Reviews in Toxicology, 2003, vol. 33, no. 6). Also in 2003, the CDC issued a report stating that “median phthalate exposures” remain far below levels that could adversely affect humans.
Still, controversy continues, especially about soft plastic toys and teethers, which usually are not labeled as containing PVC. Following a four-year scientific review, the U.S. Consumer Product Safety Commission recently declared PVC toys safe. The Toy Industry Association claims that generations of children have played with, and sucked on, toys made from pliable vinyl, with no evidence of adverse effects.
On the other hand, the environmental watchdog group Greenpeace has called on American toy manufacturers to phase out PVC plastic toys since 1996, and many companies have complied. (Their Toy Report Card, which grades major toy manufacturers on PVC use, can be found at www.greenpeaceusa.org.) In 1999, the European Union banned production of PVC teething toys for children 3 and younger, claiming they “present a serious and immediate risk to health.”
PC plastic—commonly found in food-can linings, baby bottles, 5-gallon water jugs, and Lexan (Nalgene) water bottles—may also be a health concern. Bisphenol-A (BPA), used in the production of PC plastics, is a known xenoestrogen (a compound that mimics estrogen in the body) and endocrine disrupter. BPA has been linked in mice with aneuploidy, a chromosomal abnormality causing spontaneous miscarriages, birth defects, and mental retardation (Current Biology, 2003, vol. 13, no. 7), as well as early puberty, prostate cancer, and reduced sperm count.
The American Plastics Council (APC) challenges such studies, on the basis that their relevance to human health has not been established. Claiming that BPA has been “safely used” for more than 40 years, the APC cites other research that has found no basis for health concerns from BPA exposure through PC products (Toxicological Sciences, 2002, vol. 68, nos. 121–146). (The cited study, however, used rodents and was largely sponsored by plastics manufacturers.)
As with PVC, several experts counsel avoiding PC altogether. To be safe, Myers advises using baby bottles made of glass or polyethylene and stainless-steel water bottles.
“The chemical industry is spending an incredible amount of money to convince us that their chemicals are totally safe and inert,” Crinnion says. “But we were told DDT, formaldehyde, and vinyl chloride were safe and nontoxic. [The manufacturers] have not been proved correct once.”
Before you start tossing out your plastic collection, it’s important to note that not all plastics have been proven problematic. Most water bottles, as well as soda, juice, and sports-drink bottles, yogurt cartons, bread bags, boil-in-bag pouches, cereal-box liners, and food-storage bags (such as Ziploc) are examples of food-grade plastics with no known health hazards. (See “A By-the-Numbers Guide to Safety,” below.)
Most important, food-grade plastics must be used properly. “You want to use plastics for what they were intended for and approved for,” says the FDA’s Machuga. Heat, fat, and wear and tear all speed up the leaching process. So don’t microwave plastic that’s not specified for such use (such as margarine tubs) or put top-shelf-only plastic, such as children’s sippy cups and baby bottles, on the bottom shelf of a dishwasher. Remove cling wrap from any store-bought meats, cheeses, and fish. And if a plastic container starts to look cloudy or gets scratched up, toss or recycle it.
How Plastics affect The Environment
It’s hard to miss the “Made in China” stamp on the countless plastics products sold in the United States. Most plastics are produced today in countries such as China and Mexico because of lower production costs and looser environmental restrictions. “Countries [like China] suffer the highest rate of environmental degradation on the planet,” says Gabriel Filippelli, PhD, professor and chair of the department of geology studies at Indiana University-Purdue University in Indianapolis.
The petroleum-based solvents used to make plastics don’t hurt just fish and plants—they affect humans as well. Tens of millions of Mexicans and Chinese ingest solvent-riddled waters, Filippelli notes, while workers in plastics factories breathe noxious fumes that hurt cells in the lung lining, increasing the risk of emphysema and cancer. A recent Israeli study linked occupational PVC exposure with headache, tingling of limbs, and sore eyes (American Journal of Industrial Medicine, 2001, vol. 40, no. 2).
In the United States, most workers are no longer exposed to toxic chemicals. However, says Filippelli, “many solvents in plastic-production facilities can easily leak from their source tanks into the subsurface, which can contaminate groundwater.”
Benzene, a common solvent and building block for plastics manufacture, can cause temporary nervous-system disorders, as well as long-term chromosomal aberrations and cancer, according to the Environmental Protection Agency. (In 1995, the EPA required all water suppliers to collect and analyze water samples regularly for benzene levels above the limit.)
Although gasoline and pesticides are major groundwater contaminators, Filippelli says that plastics are “equally problematic.” In 1992, the industry produced 567 million pounds of toxic waste, according to the EPA. That same year, companies put about 25 percent of their total waste back into the environment.
Most American cities have some groundwater contamination due to solvent leakages. The U.S. National Research Council estimates that costs of cleaning up the known 300,000 to 400,000 heavily contaminated groundwater sites could be as high as $1 trillion over the next 30 years.
Plastics and Your Landfill
Beyond the risks and costs associated with making and using plastics, there is another challenge: trying to dispose of mountains of nonbiodegradable material. Plastics take up 25 percent of landfill space in the United States. Although many are easily compacted, “plastics will persist in landfills for easily anywhere from 10,000 to 100,000 years,” says Filippelli.
Thankfully, biodegradable plastic alternatives are being developed around the world. Starch-based biodegradable plastics, for instance, take only a few weeks to a few months to dissolve in composting facilities. Santa Barbara, California-based EarthShell Corporation provides biodegradable packaging to McDonald’s restaurants and markets biodegradable sandwich wraps made from limestone and potato starch. Wild Oats natural foods stores are pioneering the use of Cargill Dow’s biodegradable, clear plastic deli containers, based mainly on corn-derived polylactic acid. (For optimal results, most customers return the containers to stores for composting.) And recently, Irish scientists discovered a bacterial strain that detoxifies styrene, a toxic by-product found in Styrofoam, and turns it into a safe, biodegradable product; they are conducting pilot-scale fermentations and exploring large-scale applications.
Recycling plastics can help cut down on waste, too. If every American household recycled just 1 of 10 HDPE (number 2) bottles used, it would keep 200 million pounds of plastics out of landfills annually. Recycled plastics are used for fleece clothing, luggage, garden hoses, egg cartons, and dozens of other products. Most major urban areas have programs for PETE and HDPE (numbers 1 and 2), the most commonly recycled plastics. Yet in 2002, Americans recycled just 21 percent of their plastic beverage bottles.
Many experts agree that the best way to diminish these unfavorable effects is simply to cut down on plastics’ use. Glass and ceramic make safe storage containers; waxed-paper sheets and bags, as well as parchment paper, are alternatives to plastic wraps and bags. “There are so many exposures to plastics that we can’t control,” says Crinnion, “but what’s in the air of your home and in the food you choose to buy and eat is in your control.”
Julie Rothschild Levi is a frequent contributor to Delicious Living (www.deliciousliving.com)