Can you drink from a bottle left in the sun?

“The hotter the temperature, the more plastic can end up in food or drinking water,” says Rolf Halden, director of the Center for Healthcare Environmental Engineering at the Biodesign Institute at Arizona State University.

Most plastic products release small amounts of chemicals into the drinks or foods they contain. As the temperature and exposure time increase, the chemical bonds in the plastic are more and more broken, and the chemicals are more likely to end up in food or water. According to the US Food and Drug Administration (FDA), the amount of chemicals released is too small to cause health problems, but in the long run, small doses can lead to big problems.

Disposable bottle on a hot summer day

Most water bottles you find on supermarket shelves are made from a plastic called polyethylene terephthalate (PET). A 2008 study by Arizona State University researchers showed how heat accelerates the release of antimony from PET plastic. Antimony is used to make plastics and can be toxic in high doses.

In laboratory experiments, it took 38 days for bottles of water heated to 65 degrees to detect levels of antimony that exceeded safety guidelines. “Heat helps break chemical bonds in plastics, such as plastic bottles, and these chemicals can migrate into the drinks they contain,” writes Julia Taylor, a plastics research scientist at the University of Missouri.

In 2014, scientists found high traces of antimony and a toxic compound called BPA in water sold in Chinese water bottles. In 2016, scientists found high levels of antimony in bottled water sold in Mexico. Both studies tested water at conditions in excess of 65°, which is the worst-case scenario.

According to the International Bottled Water Association industry group, bottled water should be stored under the same conditions as other food products. “Bottled water plays an important role in emergencies. If you’re on the verge of dehydration, it doesn’t matter what the water is in. But for the average consumer, using plastic bottles will not bring any benefit,” Halden said.

Thus, plastic bottles should not be exposed to bright sunlight for a long time, and also should not be left in the car in summer.

How about reusable containers?

Recyclable water bottles are most commonly made from high-density polyethylene (HDPE) or polycarbonate. HDPE is mostly accepted by recycling programs, unlike polycarbonate.

To make these bottles hard and shiny, manufacturers often use Bisphenol-A or BPA. BPA is an endocrine disruptor. This means that it can disrupt normal hormonal function and lead to a host of dangerous health problems. Research links BPA to breast cancer. The US Food and Drug Administration (FDA) bans the use of BPA in baby bottles and non-spill bottles. Many manufacturers have responded to consumer concerns by phasing out BPA.

“BPA-free doesn’t necessarily mean safe,” Taylor says. She noted that bisphenol-S, which is often used as an alternative, is “structurally similar to BPA and has very similar properties.”

How high are the risks?

“If you drink one PET bottle of water a day, will it harm your health? Probably not,” says Halden. “But if you drink 20 bottles a day, then the question of safety is completely different.” He notes that the cumulative effect has the greatest potential impact on health.

Personally, Halden prefers a metal water bottle over a reusable plastic one when he hits the road. “If you don’t want plastic in your body, don’t increase it in society,” he says.

Leave a Reply