14 DAY TRIAL // Bisphenol A (BPA) was investigated in the 1930s during the search for synthetic estrogens. Diethylstilbestrol proved more powerful than estrogen, so bisphenol A was not used as a synthetic estrogen. Currently, it is a primary monomer in polycarbonate plastic and epoxy resins. Bisphenol A is also employed as an antioxidant in plasticizers and as an inhibitor for polymerization in PVC. These plastics are a common constituent of many products, from sunglasses and CDs to water and food containers and shatter-resistant baby bottles.
Some polymers employed in dental fillings also contain bisphenol A, while epoxy is a common coating for the inside of cans in food industry. BPA leaks from plastics get cleaned with harsh detergents containing acidic components or at high temperatures, and now most people in developed countries present this chemical at very low concentrations. The chemical has been linked by some researches to sterility in women.
A new research made at the University of Cincinnati (UC) and published in the journal Toxicology Letters has come with worrying news: old plastic bottles leak as much BPA as the new ones, and hot temperature boosts the BPA amounts released into the liquid by 55 times.
"Previous studies have shown that if you repeatedly scrub, dish-wash and boil polycarbonate baby bottles, they release BPA. That tells us that BPA can migrate from various polycarbonate plastics. But we wanted to know if 'normal' use caused increased release from something that we all use, and to identify what was the most important factor that impacts release," said lead researcher Dr. Scott Belcher, UC associate professor of pharmacology and cell biophysics.
"Inspired by questions from the climbing community, we went directly to tests based on how consumers use these plastic water bottles and showed that the only big difference in exposure levels revolved around liquid temperature: Bottles used for up to nine years released the same amount of BPA as new bottles."
The team analyzed BPA release in water bottles from a local climbing gym and new bottles of the same brand. For seven days, the bottles were tested in conditions of normal usage during backpacking, mountaineering and other outdoor actions. The BPA released levels were the same for new and used polycarbonate drinking bottles. The difference was the BPA levels boosted when bottles were put in brief contact to boiling water.
"Compared to the rate of release from the same bottle, the speed of release was 15 to 55 times faster," said Belcher. This translated from 0.2 to 0.8 nanograms per hour to 8 to 32 nanograms per hour.