Coming on the heels of the National Toxicology Program's (NTP) recent report on the safety of bispheonl A (BPA), a type of polycarbonate plastic that is commonly used in food and drink packaging, a new study points to additional, previously unrecognized health concerns. Together, these reports create a body of information, while not proving causality, certainly raises the level of concern regarding human exposure to this ubiquitous plastic.

What are the health concerns related to BPA? Recently, the National Toxicology Program (NTP) released a report summarizing the potential health risks associated with BPA. There are at least two ways of interpreting this report. On one hand, the report reaffirmed concerns reported this spring that that BPA may have an effect on mammary glands and maturation of females during early puberty, as well as indicating several newer, potential health risks. On the other hand, the level of concern was relatively low, with none of the issues reaching a level higher than "some concern" on a 5-point scale with "some concern" representing the mid-point. The program concluded that more research is needed to understand exactly how these findings relate to human health and development. Specifically, the NTP reported:

• Some concern for the effect of BPA on the brain, behavior, and prostate gland in fetuses, infants, and children.
• Minimal concern for effects of BPA on the mammary gland and an earlier age for puberty for females in fetuses, infants, and children.
• Negligible concern for fetal or neonatal death, birth defects, or reduced birth weight and growth in babies born to women exposed to bisphenol A during pregnancy.
• Negligible concern that exposure to bisphenol A will cause reproductive effects in non-occupationally exposed adults and minimal concern for workers exposed to higher levels in occupational settings.

Perhaps even more bothersome, however, is a study published this week in the Journal of the American Medical Association that raised new concerns about the health effects of BPA. This study found that those with the highest levels of BPA in their urine had nearly three times the risk of heart disease and more than twice the risk of diabetes as those who had the lowest levels.

Where is BPA found? BPA is used in a number of consumer goods, including the lining of metal cans and plastic beverage containers. It is also used to make infant bottles, compact discs, impact-resistant safety equipment, and medical devices. Epoxy resins are used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes. Some dental sealants and composites may also contain BPA.

How does BPA get into the body? The primary way that most people are exposed to BPA is through the diet. BPA can leach into food from the protective internal epoxy resin coatings of canned foods and from consumer products such as polycarbonate tableware, food storage containers, water bottles, and baby bottles. A study conducted by the Centers for Disease Control in 2003-2004 found detectable levels of BPA in 93% of people six years and older that they studied. In spite of this widespread exposure, no one has confirmed its safety in humans.

Does this mean that BPA will be banned from use? Not yet. At this time, the U.S. Food and Drug Administration (FDA) continues to consider the level of exposure to BPA in humans too low to pose a health risk. Even the AMA study, while noting that those with elevated BPA levels were more likely to have heart disease or diabetes, did not prove that BPA caused those diseases. It is conceivable that the individuals with heart disease or diabetes had a generally unhealthy lifestyle that included eating high fat foods contained in cans and drinking sugared soft drinks in polycarbonate containers. In other words, their exposure to BPA was higher than average, but they may have developed the illnesses anyway.

What can I do to limit my exposure to BPA? If you are convinced that BPA poses a significant health risk, there are ways that you can reduce your or your family's exposure:

• Avoid products in polycarbonate containers that contain BPA. These usually have a recycling symbol with the number 7 on them (the #7 category also includes and other types of plastic that do not necessarily contain BPA).
• Instead, opt for containers made of glass, carboard, or stainless steel.
• Don't micowave or heat food containers containing polycarbonate.
• Use baby bottles that do not contain BPA (Born Free, Green to Grow, and ThinkBaby make BPA-free plastic baby bottles).

Clearly, more study is needed to help resolve the issue. In the meantime, some states are considering restricting the use of BPA and certain retailers including Wal-Mart and Babies "R" Us are voluntarily backing away from selling baby bottles containing BPA. Even the company that manufactures the popular Nalgene brand of water containers have decided to phase out the use of BPA in their products. An advisory panel to the FDA is reviewing existing information regarding the health effects of BPA and will be reporting to the FDA in the near future. Perhaps new guidelines regarding human exposure to BPA or the use of BPA in food or beverage containers will be forthcoming. I'll stay tuned to this issue and report new developments in future Health Tips.