Storage of bottled water has become common place in many vehicles, especially during the summer months. While there are few problems arising from this practice while using glass or stainless steel, there are many concerns relating to plastic water bottles, which is still the majority and number choice made by consumers.
Drivers can certainly relate to finding a lost water bottle on the floor of the car and quenching their thirst, no matter how long the bottle has lived there.
According to the Centers of Disease Control and Prevention, when temperatures outside range from 80 degrees to 100 degrees, the temperature inside a car parked in direct sunlight can quickly climb to between 130 to 172. The upper scale on this range is higher than the "low" temperature setting on most conventional ovens.
In terms of heat-rise over time, it makes very little difference whether a car's windows are closed or partially open. In both cases, a car's interior temperature can rise approximately 40 degrees within one hour, even when the exterior temperature is only 72F according to a study from the American Academy of Pediatrics.
While there haven't been widespread outbreaks of illness linked to consumption of contaminated bottled water, bottled water can indeed contain microbes at levels capable of making a person with a weak immune system sick. Bacteria may come from the water source, or can be introduced during the bottling process and multiplied with modest heat. But microbes are just one problem, plastic is another.
Plastic Still A Serious Problem In Bottled Water
A University of Florida study looked at 16 brands of bottled water, and the findings might throw a wrench in current FDA recommendations surrounding bisphenol A (or BPA) levels in plastic water bottles.
BPA is a dangerous chemical linked to health concerns from digestive problems to issues with brain development. It's was found present in around two billion products in the U.S. that are used on a daily basis. Because it's the most harmful on developing brains and bodies, children and pregnant women especially need to avoid contact with BPA.
Although there are simple ways to avoid BPA governments are not proactive about releasing that information to the public. The fact that exposure to BPA as a fetus is carried throughout adulthood is a cause for great concern.
While the current low levels in the plastic have been deemed safe, the researchers for this latest study watched these supposedly harmless levels grow over a four-week period when left in 158-degree heat. Even the FDA has warned to keep hot or boiling liquids out of packaging containing traces of BPA, due to its reactivity with heat.
Plastic water bottles are made from polyethylene terephthalate, a material that's used for a lot of food and beverage packaging since it's lightweight, durable, and shatterproof. However, when heated, it is known to release the chemical BPA, which can affect hormone levels by mimicking estrogen, and may trigger health risks if exposed at high levels. While the initial levels of BPA found in the 16 brands--save for one--did not exceed EPA standards for these chemicals, scientists are more concerned about how the chemicals increased over time.
Some manfacturers have made sensational claims that BPA has been substituted for other safer plastics. "Companies that said they had eliminated BPA or were in the process of doing so did not disclose the substitutes they were using," so it's unclear if the BPA-free products were using compounds similar to BPA, such as bisphenol-S, which has been shown to exhibit similar health impacts to BPA.
“If you store water long enough, there may be a concern,” study leader Lena Ma said in a press release.
The public should also be aware that re-using disposable plastic water bottles at any temperature can be harmful if they are not cleaned and dried properly. Accumulating pathogens can make people sick if ingested, causing vomiting or diarrhea. This is true with other types of containers, not just disposable water bottles.
So if you've store a water bottle in your vehicle for an undetermined period of time, throw it out and switch to glass or stainless steel.