Ecosystems of the Gut
The chemical bisphenol A (BPA) is commonly used in much of the plastic manufactured for food containers and in the lining of food cans…despite the fact that it has been shown to leach into the foods that come in contact with it. Now, a study has "surprisingly" found that after we have eaten foods containing BPA, it is undetectable in blood samples even when it is present in large amounts in urine samples.1
The research, which took place at Pacific Northwest National Laboratory in Richland, Washington and was funded by the Environmental Protection Agency, compared levels of bioactive BPA in the blood with those in the urine over the course of 24 hours. The scientists took blood and urine samples from 20 adult participants every hour during the day and several times during the night for a full day's worth of testing. The subjects all ate three meals that day of foods that came from BPA-lined cans.
Clearly, the BPA was getting into the volunteers' bodies since their urine levels of the chemical were consistently high. But the fact that even when urine levels were at their peak, BPA was barely registering in the blood samples is interesting to say the least. The question is: does that mean that BPA is less of a concern than we thought? A food packaging trade group immediately hailed the results, offering them as proof that there shouldn't be any negative health effects due to exposure to BPA. Even the lead researcher on the study seems to think that this means BPA's public health risk is very low.
In fact, these results do nothing to prove that BPA doesn't harm us regardless of whether it's measurable in the bloodstream or not. It simply reminds us that we get a good deal of exposure to it from many of our food sources. One would hope that most of us don't eat canned foods three times a day as the volunteers in the study did, but take a good look at the foods in your kitchen, the meats and cheese wrapped in plastic in your refrigerators, and the water and beverages packaged in disposable bottles you drink, and you will realize just how many items come packaged in plastic or plastic-lined cans.
Previous research has already found that BPA is an endocrine disruptor that mimics estrogen. And it is a particularly worrisome matter when it comes to exposure in fetuses and young children. A 2007 study found that exposure to either natural or synthetic estrogen, such as BPA, before birth increases the sensitivity of the fetus's prostate gland to both estrogens and androgens because it boosts genetic production of androgen and estrogen receptors.2 These sex hormones guide the prostate's growth, increasing the chances that there will be long-lasting -- possibly even life-long -- effects of this exposure.
And keep in mind, it does this without ever being detectable in the mother's bloodstream.
And those "experts" who call BPA safe because it is only measurable in the urine of adults clearly haven't been following the research on the chemical. For instance, a 2010 study at the University of Exeter in Great Britain found that BPA appears strongly linked to coronary heart disease.3 The scientists reviewed data revealing BPA concentrations in the urine samples of 1,493 adult subjects. They found that those with the highest concentrations of BPA were twice as likely to have coronary heart disease compared to those with the lowest levels. And this was the second study to find just those results. Once again, being measurable in the bloodstream was irrelevant to the results.
The risks of BPA exposure, unfortunately, extend far beyond heart disease. Over 150 peer-reviewed studies have liked BPA exposure to issues including cancer, Alzheimer's, Down syndrome, obesity, and developmental and reproductive abnormalities. Yet BPA remains pervasive in products and the environment at large. The U.S. government does nothing to protect us either. The FDA still refuses to impose limitations on this chemical.
So it's up to us as consumers to do our best to avoid BPA as much as possible. Choose glass over plastic and plastic-lined cans whenever you can. When you do use plastic, make sure it's BPA -free, or at the very least, don't heat it or leave it in a place like a car where it may get hot. Avoid canned goods unless they state on the label that the container is BPA-free. Whether it's making it to your bloodstream or not, the BPA is definitely in your body and affecting it for the worse.
1 Teeguarden, Justin G.; Calafat, Antoinia M.; Ye, Xiaoyum; et al. "24-Hour Human Urine and Serum Profiles of Bisphenol A During High Dietary Exposure." Toxicological Sciences. 24 June 2011. Society of Toxicology. 27 October 2011. <http://toxsci.oxfordjournals.org/content/early/2011/06/24/toxsci.kfr160>.
2 Stahlhut, Richard; Nagel, Susan; and Hessler, Wendy. "Estradiol and bisphenol a stimulate androgen receptor and estrogen receptor gene expression in fetal mouse prostate mesenchyme cells." Environmental Health News. 8 June 2007. Environmental Health Sciences. 27 October 2011. <http://www.environmentalhealthnews.org/newscience/2007/2007-0601richteretal.html>.
3 Melzer, D.; Rice, N.E., Lewis, C.; et al. "Association of urinary bisphenol a concentration with heart disease: evidence from NHANES 2003/06." U.S. National Library of Medicine. 13 January 2010. National Center for Biotechnology Information. 27 October 2011. <http://www.ncbi.nlm.nih.gov/pubmed/20084273>.