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25 July 2019 - Millions of people along the East Coast and in the Midwestern United States are under a heat watch this weekend as a massive heat wave bears down. This scorching July weekend follows what NOAA recently reported was the hottest June on record.

But before you reach for a plastic water bottle to keep hydrated, you might think twice about whether it too has been wilting under a hot sun.

“The hotter it gets, the more the stuff in plastic can move into food or drinking water,” says Rolf Halden, director of the Center for Environmental Health Engineering at Arizona State University’s Biodesign Institute.

Most plastic items release a tiny amount of chemicals into the beverages or food they contain. As temperature and time increase, the chemical bonds in the plastic increasingly break down and chemicals are more likely to leach. According to the FDA, the amounts of the chemicals are too minuscule to cause health problems, but scientists looking at the long-term effects of filling our lives with plastic say all those small doses could add up in a big way.

A single-use bottle on a hot summer day

Most of the water bottles you find on supermarket shelves are made of a plastic called polyethylene terephthalate, or PET. It’s recognizable by the recycling number one and accepted by most curbside recycling programs.

A study conducted by scientists at Arizona State University in 2008 looked at how heat sped up the release of antimony in PET bottles. Antimony is used to manufacture the plastic and can be toxic in high doses, the NIH reports. In mild, 70-degree weather, the researchers measured safe levels of the chemicalin the bottled water. But the hotter the day, the less time it took for water to become contaminated.

A hot car can reach temperatures over 150 degrees Fahrenheit in the summer. In experiments, it took 38 days for water bottles heated to that temperature in a lab to show levels of antimony that exceeded safety recommendations.

“As a general rule, yes, heat helps break down chemical bonds in plastics like plastic bottles, and those chemicals can migrate into beverages they contain,” emails Julia Taylor, a scientist who researched plastic 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 antimony levels in bottled water sold in Mexico. Both studies tested water under conditions that exceeded 150 degrees Fahrenheit, representing worst-case scenarios.

According to industry group the International Bottled Water Association, bottled water should be kept in the same conditions that consumers keep other groceries.

“Bottled water has an important role in emergency situations. If you’re at risk of dehydration, it doesn’t matter what container that comes in. But for the average consumer,” says Halden, “there is really no benefit for using all these bottles.”

What about reusable containers?

Water bottles that can be used repeatedly are most often made from high-density polyethylene (HDPE) or polycarbonate. HDPE is largely accepted by recycling programs (recycling code number two), but polycarbonate is more difficult to recycle (recycling code number seven).

To make those bottles hard and shiny, manufacturers often use bisphenol-A or BPA, a compound that has come under fire for its toxicity. BPA is an endocrine disrupter, which means it can disrupt normal hormone function and lead to a slew of dangerous health issues. Studies have linked the compound to breast cancer.

The FDA bans BPA from baby bottles and sippy cups, but has found no evidence to support additional restrictions.

CONTINUE READING: https://www.nationalgeographic.com/environment/2019/07/exposed-to-extreme-heat-plastic-bottles-may-become-unsafe-over-time/?cmpid=org=ngp::mc=crm-email::src=ngp::cmp=editorial::add=Science_20190724::rid=00000000021890014955

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Publication date: 
25/07/2019
Publication Organisation: 
National Geographic
Publication Author: 
Sarah Gibbens
Keyword/s: 
No Plastic
Thematic Area: 
Marine pollution
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