New research is linking a growing number of health concerns to bisphenol A, or BPA, an estrogenlike chemical found in a variety of common plastic products. Familiar items containing BPA include water bottles and baby bottles, food storage containers, milk cartons and water pipes.
Although these products may seem sturdy and durable, scientists have known for years that the chemical structure of BPA is rather unstable, especially in the presence of heat. This chemical instability allows BPA to leach into foods and beverages that come into contact with plastic containers.
To date, BPA exposure has been tied to an elevated risk of hormonal imbalances, diabetes, liver disease, breast and prostate cancers and brain disorders. Researchers at the University of Cincinnati recently announced their findings that the chemical compound may be harmful to cardiovascular health, especially in women.
The announcement followed a study in which the scientists isolated cells from the heart muscles of female rodents and briefly exposed them to BPA. In the presence of the chemical, the cardiac cells exhibited striking changes in activity.
Further analysis revealed that the changes in cardiac cell activity led to abnormal beating of the heart. Based on their findings, the scientists concluded that even at low doses, BPA exposure markedly increases the occurrence of cardiac rhythm disturbances in females.
The results of another recent animal study indicate that women who are exposed to BPA during pregnancy may give birth to offspring with permanent reproductive problems. Scientists at Yale University School of Medicine found that BPA exposure during pregnancy had lasting effects on one of the genes responsible for fertility and uterine development.
In spite of this mounting evidence, bisphenol A currently is deemed safe for humans by the U.S. Food and Drug Administration, based on estimates that Americans consume only small amounts of the chemical daily. New research suggests that the average American's exposure to BPA is far greater than previously estimated.
In a recent experiment, scientists at the University of Missouri fed BPA to five female adult monkeys. The amount fed to the animals was 400 times greater than the estimated human exposure and eight times greater than the estimated safe daily dose.
Even though the monkeys consumed exceptionally high doses of the chemical, their blood levels of BPA over the following 24 hours were significantly lower than the average BPA levels found in the blood of U.S. adults. The results suggest that most Americans likely are exposed to daily doses of BPA that far exceed the current estimated safe daily intake dose.
Unfortunately, BPA isn't metabolized rapidly or excreted from the human body. Researchers at the University of Rochester Medical Center found that high levels of BPA can remain in the bloodstream even after fasting for 24 hours.
Because of high levels of exposure and a slow rate of excretion, BPA may pose a serious health hazard to millions of Americans. According to data published by the Centers for Disease Control and Prevention, up to 93 percent of people in the United States have detectable levels of the chemical in their urine at any given time.
In response to growing public concern and controversy surrounding the safety of BPA, the FDA agreed to reconsider the health risks of the chemical in December 2008. It's likely that the use of BPA by manufacturers of plastic products will be regulated more tightly in the near future.
In the meantime, you can take steps to reduce exposure to BPA and the health risks it poses to you and your family. For starters, you should avoid leaving plastic water bottles or baby bottles in the car or outside in the summer heat, because high temperatures are known to increase the release of BPA from plastic.
It's also a good idea to avoid microwaving food or beverages in polycarbonate plastic containers. Polycarbonate containers with BPA are usually stamped with "No. 7" on the bottom.
It's wise to use containers made of glass, porcelain or stainless steel, especially when you're preparing or serving hot foods or liquids. Only BPA-free baby bottles should be used to feed infants.
Much remains unknown about the effects BPA, but it's becoming increasingly clear that even at very low levels, long-term exposure to this chemical is potentially unsafe. If you're determined to protect your health, your best bet might be to avoid using BPA-containing products whenever you can.
Rallie McAllister is a board-certified family physician, speaker and the author of several books, including "Healthy Lunchbox: The Working Mom's Guide to Keeping You and Your Kids Trim." Her Web site is http://www.RallieOnHealth.com.