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Plastic Bottles Left in Hot Cars Can Taint Your Water With Harmful Chemicals, Experts Warn

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After a long afternoon of running errands, finding a leftover water bottle in your car may seem like a godsend. But don't be too quick in chugging that H20, as leaving plastic water bottles in your car can actualy pose some major health risks.

Is it safe to drink water that has been in a hot car?

There are a few things you need to know about drinking bottled water that's been sitting somewhere warm. This is especially true for bottles left in your car as summer temperatures soar.

“When you heat things up, the molecules jiggle around faster and that makes them escape from one phase into another. So the plastic leaches its component chemicals out into the water much faster and more with heat applied to it,” Cheryl Watson, PhD, a biochemistry and molecular biology professor at the University of Texas Medical Branch at Galveston, told TODAY.com. If you take a swill from a warm, leftover bottle, you can even taste that the water is a bit off, Watson says.

In 2014, researchers at the University of Florida let water from 16 bottled water companies heat up to 158 degrees Fahrenheit for four weeks — “what researchers deemed a 'worst-case scenario' for human consumption.”

In the end, only one of the 16 waters showed levels of antimony and BPA that exceeded the EPA's standards. (Antimony is a chemical element that's considered a carcinogen by the International Agency for Research on Cancer, which is a part of the World Health Organization.)

“I don’t want to mislead people, saying bottled water is not safe. Bottled water is fine. You can drink it — just don’t leave it in a hot temperature for a long time. I think that’s the important message,” UF researcher Lena Ma told Yahoo Health.

A Water Bottle in a Hot Car Is a Fire Hazard

OK, so how can a liquid cause a fire? Sunlight can stream through the water bottle and the liquid inside, which together act as a magnifying glass. Remember when kids on the playground used to try to burn ants with a magnifying glass? The same thing happens with the water bottle. The sun's rays focus on one point, and if that spot gets hot enough, flames can occur. Scary stuff! Don't believe us? Watch it in action.

Idaho Power shared a video, narrated by stations battery technician Dioni Amuchastegui, that shows a part of Amuchastegui's car seat starting to smoke. If you look closely, you can see burn marks as well. Fortunately, he noticed before things got serious.

“I had to do a double take,” says Amuchastegui. “It was hot enough to start burning a hole through the seat.”

Surviving Summer: How to Stay Hydrated

What's a girl to do if she can't keep her water bottle in the car, but she wants to make sure she's hydrated during the warm summer months?

The best option is just to carry your water bottle with you. Some containers come with handy wrist straps, but if you'd rather not have such a bulky item on your person, there's one place in the car that you can stash your bottle if you really must. Put your bottle under the seat and out of the sun's rays if you are determined to not carry it.

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