Nanjing University in China and the University of Florida have recently completed a study on the effects of storing bottled water at 3 different temperatures: 39°F, 77°F, and 158°F to mimic the temperatures of a refrigerator, a standard room, and the inside of a car on a hot summer day.

The researchers then checked the levels of two substances, antimony and bisphenol-A (BPA) after 1, 2, and 4 weeks at the respective temperatures. According to a 2009 study from Birmingham City University in the UK, antimony, a heavy metal, may play a role in lung, heart, and gastrointestinal diseases. BPA can mimic estrogen in the body and may have a correlation with liver and prostate cancer as well as migraines and miscarriages.

Researchers found that as the temperature rose and time passed, increasingly high levels of antimony were detectable in the bottles of water. Seventy-seven degrees in particular saw the release of antimony increased by almost twice than that at the cooler temperatures. However at 158°F – the inside of a car on a typical summer day – antimony concentrations increased by 319-fold compared to the levels of the bottled water at the refrigerator temperature. The BPA levels also rose at this temperature but not to high concentrations.

Though the concentrations of antimony rose significantly, the highest level measured was still lower than EPA’s legal limit. However, the lead researcher, Lena Ma, recommends discarding any bottled water that has been stored in hot conditions.

Our recommendation? Don’t take a chance – skip bottled water entirely and switch to a bottleless water cooler for cold, filtered water on demand!