Bisphenol-A (BPA)

Human exposure to Bisphenol-A (BPA) has caused a great deal of alarm in the popular media as well as the scientific community.  Surveys have shown that >93% of the US population has measurable levels of BPA metabolites in their urine—likely due to exposure from food (canned goods), water (PVC pipes), copy paper (cash register receipts), and dental materials.  It was previously thought that BPA is rapidly metabolized and excreted from the body, but the pharmacokinetics are not entirely clear—and now it is thought that low levels of BPA may be stored in and released from our adipose tissue (fat cells).

Why the concern about BPA?

Numerous animal studies have demonstrated effects of BPA on different tissues—breast tissue growth, neuroblastoma development, neurobehavioral changes,  dopaminergic system changes, thyroid dysfunction, testicular cancer, prostate cancer, reproductive disorders, and many others.  In vitro studies have also shown similar estrogenic effects to cell lines exposed to BPA and its derivatives.   Epidemiologic studies indicate a causative link between occupational BPA exposure and polycystic ovary syndrome (PCOS) in women, low follicle- stimulating hormone (FSH) levels in men, high testosterone levels in men and women as well as chromosomal defects and low birth weights due to prenatal exposure to BPA.  One large study revealed that  BPA may be associated with increased risk for cardiovascular disease, elevated liver enzymes and diabetes.  Considering the widespread exposure of the US population to BPA and BPA derivatives, these findings are greatly concerning.

Why the controversy?

Thus far, the study of BPA and human health has been limited—though several in vitro and animal studies have shown a clear correlation between BPA and hormonal disruption, demonstrating its estrogenic effects.  Several scientific panels (EU and US) have evaluated the current data and have come to a consensus that there is “some” concern for neural, behavioral and hormonal effects on humans at current levels of exposure, particularly for fetuses, infants and small children.  This unfortunately has been insufficient to sway large corporations to alter their use of BPA in food manufacturing or the FDA to approve a ban on the use of BPA in food packaging (rejected 3/30/12).  Several states in the US (as well as Canada, EU, China, United Arab Emirates) have banned the use of BPA in baby bottles.  BPA has been used since the 1940s to harden plastics and to manufacture the epoxy resin that lines food and beverage containers, and in countless other products.  An  estimated six billion pounds of BPA are produced globally each year, and can enter the environment by leaching from plastic and metal waste in landfills as well as ocean-borne plastic trash.  Some industry groups argue that the low level of BPA exposure is below a threshold, and is not necessarily a cause for alarm.  Current research does show, however, that even low doses of this estrogenic compound can have adverse effects on human health—and some scientists recommend lowering the EPA’s reference range for “acceptable exposure” to <10 micrograms/kg body weight (currently 50 micrograms/kg).

BOTTOM LINE:  I personally limit BPA exposure by avoiding canned food (or using BPA free cans such as Eden Foods), using BPA free water bottles (such as Kleen Kanteen or Nalgene BPA free) and crossing my fingers with regard to my dental sealants and fillings.  We also filter our drinking water with a reverse osmosis water filtration system.

To read more, please see BISPHENOL-A (BPA) dental sealants


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