By Stephen Musson, University of Florida
Bisphenol A (BPA) is a chemical compound used to create polycarbonate plastic and epoxy resins. BPA-derived plastics, commercially produced since the 1950s, have become ubiquitous because of their shatter resistance, visual clarity, high heat resistance, and electrical resistance. Polycarbonate plastics are found in an enormous range of products, including eyeglass lenses, CDs and DVDs, personal computers, appliances, power tools, sports equipment, medical devices, and food and drink containers. Epoxy resins are easily formed and resist chemicals, which makes them useful in products such as printed circuit boards, paints and adhesives, dental sealants, and coatings for the inside of metal cans.
Over time, the chemical bond connecting the BPA building blocks deteriorates, releasing BPA molecules. The quantity released is typically very low, but the plastics are so widespread—they're in baby bottles, water bottles, metal food cans, food storage containers—that people are regularly exposed. In a 2003-2004 study by the U.S. Centers for Disease Control, nearly 93 percent of the people tested, age six and above, had detectable bisphenol A in their urine; females had slightly higher levels than males.
The health effects of bisphenol A are widely disputed. The amounts that leach into food are well below the safety thresholds set by the U.S. Environmental Protection Agency (EPA) and the European Commission Scientific Committee on Food. The EPA safety level is based on toxicity testing conducted in the 1980s that showed weight loss in rats given 50 milligrams of BPA per kilogram of body weight each day.
Traditional toxicity testing, including the EPA study, relied upon the idea that a chemical would have no detrimental effect below a certain dose. Tests were conducted by using relatively high doses and then either increasing the dose until an adverse effect was seen or decreasing it until the adverse effect was no longer observed. But subsequent research suggests that for some chemicals, including BPA, a second threshold exists below which similar or new adverse effects occur.
These low-dose effects are commonly associated with the endocrine system, the chemical communication system found in humans and most wildlife. While the nervous system is the rapid communication system controlling functions such as heartbeat, breathing, and movement, the endocrine system typically handles long-term functions and processes, including the development of the brain, nervous system, and other organs and tissues; growth and metabolism; and the functioning of the reproductive system. Hormones are the chemical messengers of the endocrine system, and chemical compounds that mimic hormones, affect their production, or prevent them from reaching their target are known as endocrine-disrupting compounds, or EDCs.
Critics of BPA cite the potential effects of low doses as a cause for concern. Research has shown that BPA mimics estrogen, a naturally occurring hormone, and therefore can affect the body's endocrine system. BPA's effects are often most pronounced when humans are in stages of rapid development, such as in the womb or during childhood. Laboratory studies conducted since the 1990s have noted that low-dose BPA exposure may be connected to abnormal penis development in males, early sexual maturation in females, an increase in neurobehavioral problems such as attention deficit hyperactivity disorder (ADHD) and autism, an increase in childhood and adult obesity and type 2 diabetes, and an increase in hormonally mediated cancers, such as prostate and breast cancers.
As concerns over the potential health effects of BPA exposure have become publicized, manufacturers, consumers, and governments have taken steps to reduce BPA use and exposure. In April 2008 Canadian regulators announced a ban on the use of BPA plastics in baby bottles. As a result, the European Food Safety Authority is now considering whether to take a similar step, and U.S. lawmakers have introduced a bill to ban its use in children's products. In the meantime, manufacturers and consumers have already begun taking steps to reduce BPA use. Many people are now exchanging BPA-containing plastics—including hard-plastic water bottles and baby bottles—for other plastics, glass, or stainless steel containers. Additionally, retailers such as Wal-Mart and Toys "R" Us have announced that they'll remove BPA-containing baby bottles from their stores. Still, the U.S. Food and Drug Administration released a statement in April 2008 that it isn't recommending that anyone discontinue using products with BPA while it continues to assess the risk.
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Latest news about bisphenol A. Our Stolen Future.
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By Stephen Musson, University of Florida
1. Stop using hard, clear plastic containers marked with a recycle symbol and a "7" or "PC."
2. If you must use them, avoid microwaving them. High temperatures may help break down the plastic.
3. Choose glass, porcelain, or stainless steel containers when possible, especially if they're to be used with hot foods or liquids. This will reduce not only BPA exposure but also exposure to other plastic additives such as phthalates.
4. Use baby bottles that are made from BPA-free materials such as glass or polyethylene.
5. Reduce your use of canned foods or choose brands that don't use BPA liners—some brands now advertise liner-free cans. Other alternatives include fresh and frozen vegetables.
6. Reduce your consumption of wines—some are aged in BPA-epoxy-lined containers—or look for naturally aged ones.
Last updated: July 21, 2008