This August has seen the release of two new studies involving bisphenol A (BPA) and potential health effects. Since both deal with different subjects, I'll address them separately, but each contribute to a growing body of work that focuses on BPA (commonly found in plastics and the lining used with canned foods). Previous studies have found that BPA has estrogenic properties and may lead to long term negative health consequences. While the FDA has set acceptable limits on the amount of BPA that can be used in products, they have also taken the more recent steps of recognizing BPA as an endocrine disruptor and banning the use of BPA in plastic baby bottles.

_The first study comes from California National Primate Research Center (CNPRC) and focuses on fetal BPA exposure to rhesus macaque monkeys. This primate was chosen since fetal lung development more closely resembles that of humans than previously studied animals (namely rodents). During this study, pregnant rhesus macaques received BPA via a subcutaneous implant during one of two time periods, comparable to the second and third trimester in humans). Since the study was originally meant to focus on BPA's effect on female reproductive development, only female fetuses were examined, and at the end of each group's exposure period, fetal airway tissue samples were collected and analyzed.

_With the samples, researchers looked for variations in lung and airway development. For the first group, those exposed during the ‘second trimester’, there was no significant difference in the mucous cell abundance or the secretory protein expression when compared to the control. However, those exposed during the equivalent of the last trimester not only showed a greater abundance of mucous cells, but the expression of MuC5B gene was nearly 6x higher than the samples that received no BPA exposure. The differences in samples was most pronounced in the bronchi. An increase in mucous cells is one early indicator of asthma or bronchitis, and when taken with previous research, this study seems to point towards a link between fetal exposure to BPA and respiratory development.

_It should be cautioned that this study was small, and only highlights a potential link. It is also not known whether BPA directly caused this difference between test samples or if it altered some other function during development that caused the difference. Interestingly though, another article, published in Pediatrics calls into question the use of urine concentrations of BPA as indicators of exposure. The author highlights some instances where testing has shown that the concentrations of BPA in serum (a blood fluid) was actually lower than what was recorded in urine samples and that because of the way the body metabolizes BPA, urinary concentrations might not be the best indicator. The ironic part is that while this article calls several things into question, it does note that many of the studies have not been performed on primates. The subjects of both the first and next study I'm going to mention were performed on primates, and only one used urinary BPA levels.

_The second study, published today in Pediatrics, focused on BPA and its potential link to chronic disease risk factors in children. When accounting for things like soda consumption, tobacco exposure, demographics, etc., University of Michigan researchers showed that higher levels of urinary BPA were linked to higher odds of obesity. While no connection between BPA and any other chronic disease risk factor was found, it is worth noting that BPA is a highly fat soluble substance. Though not tested, theoretically, someone who is overweight could possibly retain more BPA than someone thinner.

_All three of these articles further the debate surrounding the use of BPA, and each adds another wrinkle to the debate over the long term consequences of BPA exposure. This is important if for no other reason than this. A 2007 study, funded by the National Institute of Health (NiH), found that over 90% of urine samples collected in children and adults over the age of six has detectable levels of BPA.

_Author: K. Gilmore