The endocrine disrupting chemical bisphenol-A, or BPA, is released when polycarbonate plastic is exposed to boiling water, according to University of Cincinnati scientists, whether the bottle is new or old.
The chemical, which is widely used in products such as reusable water bottles, food can linings, water pipes and dental sealants, has been shown to affect reproduction and brain development in animal studies.
Scott Belcher, PhD, and his team found when the same new and used polycarbonate drinking bottles were briefly exposed to boiling hot water, BPA was released up to 55 times more rapidly.
Polycarbonate plastic bottles like these release bisphenol A when exposed to boiling liquid. (Photo courtesy Scott Belcher)
"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," explains Belcher, UC associate professor of pharmacology and cell biophysics. "But we wanted to know if ‘normal' use caused increased release."
"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," Belcher said. "Bottles used for up to nine years released the same amount of BPA as new bottles."
Belcher's team analyzed used polycarbonate water bottles from a local climbing gym and purchased new bottles of the same brand from an outdoor retail supplier.
All bottles were subjected to seven days of testing designed to simulate normal usage during backpacking, mountaineering and other outdoor adventure activities.
The researchers found that the amount of BPA released from new and used polycarbonate drinking bottles was the same, both in quantity and speed of release, into cool or temperate water.
But once the bottles were exposed to boiling water the speed of BPA release was 15 to 55 times faster, explains Belcher.
BPA is one of many manufactured chemicals classified as endocrine disruptors, which alter the function of the endocrine system by mimicking the role of the body's natural hormones.
"There is a large body of scientific evidence demonstrating the harmful effects of very small amounts of BPA in laboratory and animal studies, but little clinical evidence related to humans," explains Belcher. "There is a very strong suspicion in the scientific community, however, that this chemical has harmful effects on humans."
Belcher stresses that it is still unclear what level of BPA is harmful to humans, but he urges consumers to think about how cumulative environmental exposures might harm their health.
"BPA is just one of many estrogen-like chemicals people are exposed to, and scientists are still trying to figure out how these endocrine disruptors - including natural phyto-estrogens from soy which are often considered healthy - collectively impact human health," he says. "But a growing body of scientific evidence suggests it might be at the cost of your health."
The study was funded by a National Institute of Environmental Health Sciences grant. It is published in today's issue of the journal "Toxicology Letters."
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