Switching from reusable polycarbonate plastic water bottles to aluminum ones doesn't necessarily prevent exposure to the hormone-disrupting chemical bisphenol-A (BPA). That’s according to a recent study examining whether materials used for “BPA-free” reusable bottles lived up to their claims.
The study, in the journal Chemosphere, found that some types of aluminum bottles are lined with an epoxy resin that leached even more BPA into water than did the plastic bottles that they were meant to replace. Epoxy resins also are commonly used to line food and beverage cans, and a Consumer Reports investigation found that almost all of the 19 name-brand canned foods we tested contained BPA, which some studies have linked to health effects including reproductive abnormalities and an increased risk of breast and prostate cancers, diabetes, and heart disease.
The water-bottle study, however, did have some good news. It found that some newer reusable water bottles did keep beverages free of BPA when used according to manufacturers’ recommendations. They were:
• Uncoated stainless steel bottles (brands tested were Sigg and Steel Works).
• Plastic bottles made of Tritan copolyester (brand tested was Nalgene)
• Aluminum bottles lined with EcoCare copolyester (brand tested was Sigg)
To assess manufacturers’ BPA-free claims, the researchers stored room-temperature BPA-free purified water in each type of bottle for five days and then tested that water. They found the highest BPA levels in water stored in epoxy-lined aluminum bottles branded New Balance that they purchased at Target, the national discount retail chain.
The concentration of BPA in those bottles was more than five times the concentration in polycarbonate plastic water bottles they tested under the same conditions. It also was 12 times higher than the amount of BPA they detected in water stored in unused older models of epoxy-lined aluminum bottles manufactured by Sigg before August 2008, when the company began making all of its aluminum bottles with a proprietary EcoCare lining, which the study found did live up to its BPA-free claim.
A separate set of tests conducted as part of the study also found that exposing polycarbonate or epoxy-lined bottles to heat significantly increases BPA leaching. When the scientists filled the epoxy-lined aluminum bottles with boiling water and then let that water cool and sit at room temperature, the migration of BPA into the water quadrupled.
While a copper or gold color in the lining of bottles can indicate an epoxy-resin coating, color alone isn’t definitive, says Scott M. Belcher, Ph.D., an author of the study and professor of pharmacology and cell biophysics at the University of Cincinnati. For instance, epoxy linings in canned foods can be white or nearly transparent.
Bottom line: Consumers interested in decreasing their BPA exposure should use labels on reusable bottles as a guide and find out the material used to make the product, Belcher advises. “I feel that products constructed from stainless steel, Eastman’s Tritan (e.g. the plastic bottles manufactured by Nalgene) or copolyester linings can be considered not to be a source of BPA for the consumer,” he says.
Assessment of bisphenol A released from reusable plastic, aluminium and stainless steel water bottles Chemosphere