Switch to stainless steel if you have an old bottle, and limit exposure to BPA in other aluminum products, such as food and soda cans.

BPA free? If it's an aluminum bottle, probably not, no matter what the label says.

RODALE NEWS, EMMAUS, PA—The next "BPA-free product" that still contains BPA? Your Sigg water bottles. The popular Swiss manufacturer of decorative water bottles sold at Whole Foods, Target, and outdoor retailers admitted last week that despite some previous, misleading statements, they had been using the hormone-disrupting chemical bisphenol A (BPA), which has been linked to a wide array of chronic illnesses including obesity and cancer.

THE DETAILS: Aluminum water bottles need to be lined to prevent juices or other acidic drinks from reacting with the metal, which will cause the contents to taste metallic. Nearly all canned foods, soda cans, and baby formula—anything packaged in metal—are lined with an epoxy resin, of which BPA is a building block.

For years, Sigg had told its customers that they used a "water-based epoxy resin" in their aluminum water bottles, and that the resin leached no BPA. But they wouldn't disclose the exact contents of the liner, claiming it was a proprietary formula. The company had the bottles independently tested for levels of BPA and published the results of those tests online, which intentionally or not lead its customers to believe that there was no BPA in its proprietary liners. Last week, however, the company published a somewhat confusing letter on its website, stating that all Sigg water bottles are "now BPA-free." According to the letter, the company had actually been using a liner "that contained trace amounts of BPA" until August 2008, when they switched to a new plastic resin—also proprietary in makeup—that contains absolutely no BPA. In the letter, the company's CEO Steve Wasik writes, "Last year, the primary concern was that of BPA leaching from bottles. Since that time the dialogue has evolved such that now some people are concerned about the mere presence of BPA, and some states are considering legislation."