By Melvin Magadia (Published April 22, 2011)
With all the talks about unsafe drinking waters circulating worldwide, the use of polycarbonate drinking bottles rose to prominence. For years, polycarbonate plastic has been used in manufacturing baby bottles, reusable water bottles, and sippy cups. Several studies have shown that these products are safe for use. However, recently issues about bisphenol-A (BPA) finding its way into food and beverages have put into question the safety of BPA-free water bottles.
Bisphenol-A is used in manufacturing products for children, such as clear plastic bottles and canned infant formula. It is also used in manufacturing food-storage containers, clear plastic pitchers for filtered water, refillable water bottles, and the lining of soft drinks and food cans. Claims that trace amounts of the chemical has made its way from the container to food and liquids have resulted to widespread scrutiny in Canada and the United States. These issues have also caused retailers such as Wal-Mart, Nalgene, and Playtex to withdraw products made from BPA and stopped using it.
While there have been evidence proving that polycarbonate bottles are indeed safe, myths as well as scare stories have clouded the results of these studies. For instance, during the mid-1990s, there were claims that low doses of bisphenol-A resulted to adverse health effects by disrupting the normal hormonal functions. The most common claim centers on reproduction and development. The so-called “low dose hypothesis” fueled claims that non-monotonic dose-response causes effects in low doses but not in higher doses, a contradiction to the basic toxicological principle “the dose makes the poison.”
One such myth claims that BPA levels released from polycarbonate plastic bottles increased when filled with boiling water and remained at that level when filled with water at room temperature. However, a comprehensive study conducted by researchers from the University of Athens found that the increase in BPA levels is a transient effect that returns to baseline level with continuous use. Likewise, the extreme level of BPA in the new studies was well below science-based safety standards of government bodies. Aside from that, it is normal for migration levels to increase with elevated temperature.
In 2008, the Dutch research organization TNO subjected the claim that heating baby bottles in a microwave oven would elevate BPA migration to unsafe level to a series of studies. The researchers used polycarbonate bottles from eighteen European brands in determining BPA migration level in actual microwave heating or sterilizing temperatures. They were filled with water, subjected to boiling temperature under microwave heating, boiled for a minute before it was cooled down. After rinsing, the procedure was repeated a couple of times more.
After a series of tests, the TNO study concluded that heating the bottles in the microwave oven would have no effect on the level of migration of BPA from polycarbonate bottles. Thus, warming the contents or sterilizing the bottles in the microwave oven is a safe practice. Again, the migration level in the studies was well within science-based safety standards.
On the claim that the polycarbonate bottles will degrade under dishwashing conditions as well as emit unsafe BPA levels, the combined team of the Norwegian Food Safety Authority and the Official Food Control Authority of the Canton based in Zurich, Switzerland conducted extensive studies to assess the claims. Based on the findings, the researchers reached the conclusion that even under the most extreme condition, the amount of BPA levels did not surpass the Tolerable Daily Intake (TDI). The study confirms the safety of using dishwashing solutions in cleaning polycarbonate bottles.
On the earlier claim that migration levels of BPA can have an effect on human reproduction and development, a draft report coming from the National Toxicology Program revealed that there is no direct evidence on the effects of exposure to BPA on reproduction and development. According to Dr. Michael Shelby, Director of the Center for the Evaluation of Risks to Human Reproduction, there is nothing to worry about when it comes to the potential risks of BPA migration level to reproduction and development.
New evidence shows that low doses of bisphenol A do not have an impact on the reproductive and developmental health of humans. The conclusions, published on the peer-reviewed journal Critical Reviews in Toxicology, demonstrated consistency with the assessments of government and scientific bodies worldwide. The studies, however, does not support the assumption that low doses of BPA can have adverse effects on reproduction and human development.
According to the NSF International, a non-profit public health organization, even if humans were exposed to the highest transient level of BPA on a daily basis, it would still be below the Reference Dose and Total Allowable Concentration level. The former measures the safe exposure level while the latter is a measurement of safe concentration.
A similar study conducted by the European Food Safety Authority (EFSA) came up with a Tolerable Daily Intake (TDI) for BPA at 50 micrograms/kilogram bodyweight per day, which is a safe level for daily exposure throughout a lifetime. It said that even if an individual is exposed to the maximum level of BPA, which is unlikely to happen everyday throughout the life span of an individual, it would only yield an exposure of less than 1% of the TDI.
Finally, a thorough investigation of the scientific data undertaken by government and scientific bodies worldwide shows that polycarbonate water bottles are safe to use and if there would be any exposure, it would be well within the science-based safety limits.