From ScienceNews:

Consumers who switched from polycarbonate-plastic water bottles to metal ones in hopes of avoiding the risk that bisphenol A will leach into their beverages aren’t necessarily any better off, a new study finds. Some metal water bottles leach even more BPA — an estrogen-mimicking pollutant — than do ones made from the now-pariah plastic.

That BPA doesn’t come from the metal, by the way, but from an epoxy-resin lining that is based on BPA’s recipe.

That’s the bad news.

If you’re willing to spring for name-brand bottles, however, several included in the new study either did not contain a resin liner or did not contain one that leached BPA. These data suggest such products would be a better bet for individuals who are especially risk averse. But BPA leaching by even the worst performing water bottles was low, observes toxicologist Scott Belcher of the University of Cincinnati College of Medicine, an author of the new study.

“Low is a fair characterization,” he says. “Infinitesimally low and irrelevant is not fair,” he adds, because there are so many potential sources of the pollutant in the human environment “and this is just one.” Moreover, his team confirmed, temperature abuse could — and did — exaggerate BPA releases by otherwise low-emitting bottles.

Belcher’s group has for years been testing the effects of BPA on heart-muscle cells. This work has shown that in rodent hearts, BPA exposures foster potentially life-threatening arrhythmias. And the risk intensifies in the presence of estrogen. (The team’s published data suggest that owing to the levels of estrogen present in women, the addition of substantial BPA via the diet might be capable of provoking such arrhythmias.)

After having a number of individuals plead with his team to test whether ostensibly BPA-free water bottles really were devoid of the pollutant, Belcher and his colleagues agreed to perform a series of tests. The researchers used old (but unused) polycarbonate and resin-lined aluminum bottles that they had closeted away several years earlier, along with new BPA-free “Tritan” plastic bottles (by Nalgene), stainless steel bottles (by Sigg) and new “EcoCare” resin-lined aluminum bottles (by Sigg). They also purchased some new aluminum water bottles from a major discount retailer.

After cleaning each unit, the scientists stored room-temperature water in three bottles of each type for five days. In an additional set of experiments, Belcher’s team filled the bottles with boiling water (which tests by others had shown could boost BPA leaching) and then let the water cool to room temperature over the next day.

Levels of BPA were below the limit of detection for the new Sigg and Nalgene bottles, the scientists reported early online July 8 in Chemosphere.

By contrast, the old polycarbonate bottles leached 0.17 to 0.3 nanograms of BPA per milliliter of water during the room temperature tests. The old aluminum bottles with an epoxy-resin liner (which looked golden orange) leached 0.59 to 0.14 nanograms per milliliter. Brand-new epoxy-resin-lined aluminum water bottles leached substantially more — up to six times more BPA than the worst-leaching polycarbonate bottle and more than 10 times as much BPA as the polycarbonate-plastic bottle that had leached the least.

Oh, and the hot-water test: It quadrupled BPA leaching over what occurred when water had been kept at or below room temperature.