Here's what we do know: Dozens of published lab studies, along with research looking at potential BPA-related health patterns in the general population, raise red flags. Some epidemiological studies, the ones looking across the population as a whole, suggest that people with higher blood levels of BPA face a greater risk of type 2 diabetes, heart disease, and obesity. In fact, BPA has been dubbed an obesogen by some scientists.
But BPA news may seem confusing—especially with recent headlines suggesting that most exposures may be too small to negatively affect humans. Those stories have arisen out of a presentation at the annual meeting of the American Association for Advancement of Science in Boston in February 2013. Unlike the data mentioned earlier, this new information suggesting BPA isn't harming humans was not published in a journal that other scientists fact-check and approve for release.
The government researchers presenting the new BPA data at the AAAS meeting say they created mathematical models using data from about 100 studies. The presented results from the calculations suggest the doses Americans face aren't damaging human health. One of the researchers involved with the study did reportedly receive funding from the chemical industry in the past but did not for this particular study.
Sharply disagreeing with the mathematical modeling results are many of the biologists whose work has shown evidence of BPA's estrogenic tendencies, its ability to disrupt delicate hormonal systems in lab animals, causing brain and reproductive damage and increasing breast and prostate cancer risk. In fact, one study found BPA's side effects may affect not just the health of the animal exposed, but also that of animals three generations down the line. Currently, there are about 50 published human studies looking at everyday people and linking BPA exposure to a greater risk of thyroid function, abnormal circulating hormone concentrations, sunken sperm counts, and polycystic ovarian syndrome.
"Should we ignore the 60 epidemiology studies and the 24-plus blood biomonitoring studies? Should we ignore the hundreds of animal studies that have shown effects of BPA within the range of suspected human exposures?" asks Laura Vandenberg, PhD, a postdoctoral fellow of biology at the Center for Developmental and Regenerative Biology at Tufts University in Massachusetts. "I would definitely say no."
Vandenberg points out some issues with the modeling of BPA as an estrogen. For example, if BPA is really found in the tiny part-per-trillion range in human blood, that may not rule out biological effects because our natural hormones are known to operate at those levels. Another issue? Scientists don't fully know exactly how BPA acts, or how it interacts with the dozens of other industrial chemicals routinely found in the human body. A recent study by the National Toxicology Program examined 309 environmental chemicals and assigned BPA the third-highest toxicological priority score. Why? It interacts with a number of other receptors in the body, not just ones dealing with estrogen.
Other major organizations around the world seem to agree. A new report from the World Health Organization and the United Nations Environment Programme recently dubbed endocrine disruptors like BPA a "global threat."
Whether you agree with that or not, here are some BPA facts no one can argue: It's found inside of the bodies of the vast majority of us, and though we may be able to clear it from our bodies pretty quickly, constant exposures mean BPA is likely constantly running through our veins. While different governments around the world take different approaches to dealing with the chemical, more and more scientists are publishing data suggesting it poses threats at very, very minute doses.
In fact, in a recent Environmental Health News article, National Institute of Environmental Health Sciences director Linda Birnbaum said, "We're seeing effects in animals at very, very low concentrations and also seeing associations in a large number of epidemiological studies. We know we're seeing activity at the picogram [one trillionth of a gram] level."
Want to practice the precautionary principal and avoid BPA now? Use these tactics to cut down your exposure:
Can canned food. Reducing the amount of foods and drinks from a can you consume may help lower your BPA exposure. Opt for fresh or frozen instead, or foods packaged in aseptic "brick" cartons.
Say "no" to pointless receipts. When making trivial purchases, say you don't need a receipt. While we don't currently know exactly how absorbing the chemical through skin harms humans, we do know that BPA readily slides off of thermal receipts and can be absorbed into your body. Be wary of some "BPA-free" receipts and products, too. A 2013 University of Texas study looking at BPA replacements found one popular alternative chemical also shows estrogenic activity.
Go plastic-free. Avoid #7 polycarbonate plastics, especially if you're storing food or drinks in them. Instead, opt for glass, food-grade stainless steel, or ceramic containers.
Grill your dentist. If you need resin fillings, ask your dentist if the filling material or sealant contain bisphenol A diglycidyl ether, or BADGE. This chemical breaks down into BPA and was linked to obesity in a 2012 study appearing in the journal Environmental Health Perspectives. Since much exposure is believed to happen at the time of the filling, ask to rinse promptly after the dentist seals your filling.