Previous study has shown that BPA migrated into water from polycarbonate drinking bottles and that amounts of BPA were proportional to incubation time(Le et al., 2008
). The main goal of the study was to determine whether or not the commercially available materials used for reusable water bottles were indeed free of BPA that could migrate into water stored in these vessels. Because BPA is widely used in the manufacture of many consumer products, especially plastics where it is used as a plasticiser or a stabilizing coating for many forms of plastics and other materials, it is difficult to know based solely on the nature of the polymer whether the materials are truly free of BPA. Because of the proprietary nature of many of the alternative polymers or linings, and the lack of rigorous and independent confirmation of BPA-free claims, there is a level of scepticism surrounding manufacture’s marketing claims that their products are “safe” or “BPA-free”. Eastman’s polycarbonate alternative Tritan™ is a copolyester polymer that is being used to manufacture “BPA-free” water bottles. In agreement with manufactures statements, our analysis found that BPA was not detected in water incubated in Nalgen branded water bottles made of Tritan. As anticipated, the uncoated stainless steel bottles similarly did not leach BPA in to water.
During the 120 hour incubation period used in the current study the amounts of BPA (mean = 0.23 ng/ml; range 0.18 to 0.31 ng/ml; n=4) migrating into water from the positive control polycarbonate bottles was comparable, but lower (p=0.0444) than the levels reported previously by Le and co-workers(2008)
over the same incubation period (mean = 0.52 ng/ml; range 0.28 to 0.68 ng/ml; n=3). This finding may be due to a relative decrease in sensitivity of the assay. Quality control studies suggest that differences can result due to cumulative effects of small variations in experimental conditions or the ELISA assay itself (e.g. variations in goodness of standard curve fits orreagent/antibody characteristics). However the observed difference in migration could be related in unknown ways to the age of the bottles – the bottles used here were acquired at the same time as those used by Le et al (2008)
, and stored in the dark unused for more than 2 years under climate controlled laboratory conditions (22°C).
The Swiss supplier Sigg manufactures aluminium bottles that have a BPA-free liner (EcoCare™) with a proprietary formula. There was some concern in 2008 that water bottles manufactured by Sigg were made with an epoxy-based liner that theoretically could leach BPA; however, the manufacturer purportedly claimed that extensive testing had revealed that the lining did not leach BPA. Since August of 2008 all Sigg bottles were manufactured using the EcoCare™ liner, which is guaranteed to contain no BPA. Consistent with that claim, BPA was undetectable in water samples following incubation in EcoCare™ lined Sigg bottles. Testing of the BPA leaching properties of Sigg bottles that were manufactured prior to August 2008 revealed that low, but detectable levels of BPA were migrating into water incubated in these older epoxy resin lined bottles. Upon adding heated water to those bottles, the migration of BPA was increased. Clearly BPA migrates from these linings, and while not absent, the amounts of BPA migrating into the water is considered low and unlikely to constitute a major source of BPA for the consumer if the manufactures guidelines of consuming liquids relatively rapidly and not storing heated liquids in the bottles are followed.
One of the most interesting results was the comparison of the epoxy lined bottles from a discount retailer with those from Sigg. The discount epoxy lined bottles, released much higher levels of BPA even without first being exposed to high temperature liquid. The difference in the amount of BPA migrating from the discount aluminium epoxy lined bottles and those manufactured by Sigg was 12 fold. In fact, the concentrations of BPA in water exposed to those bottles was more than 5 times the concentration of water samples from polycarbonate bottles which have a significantly larger internal surface area.Along with higher temperatures increasing the BPA migration from polycarbonate, these studies indicate that elevated temperatures greatly increase the liberation of BPA from epoxy-based liners; these studies have confirmed that there areunknown variables related to the manufacture of the epoxy liners that determines how much BPA migration occurs. Those variables are unknown, however the observations reported in this study is that under normal, and especially after exposure to extreme condition (e.g. temperatures above manufacture recommendations) BPA can leach from epoxy resins regardless of perceived quality. However, commercially available “BPA free” alternatives in the form of plastic reusable drinking bottles and lined or unlined metallic drinking bottles were identified. No detectable BPA was observed to migrate from EcoCare™ lined aluminium, stainless steel, or Tritan™plastic water bottles. Therefore, based on the presented results it appears that reusable water bottles constructed of those alternative materials and when used according to manufacturer’s recommendations, can be considered suitable for storage and consumption of beverages free of container mediated BPA contamination.