Fact check: Plastic water bottles left in hot cars don't release dioxins, do leach other chemicals

The claim is that heat reacts with plastic water bottles chemicals and releases dioxin.
Are water bottles able to leach cancer-causing chemicals when they are exposed to extreme heat?

On Oct. 3, 2019, a Facebook user shared an image that showed a warning sign with the words "Bottled Water in Your Car is Very Dangerous!"

Nearly 160,000 people shared the two-year-old post, many of which were shared in October when the post was revived online.

The post states that Sheryl Crow, a singer, said that she was diagnosed with breast cancer after drinking dioxin from a water bottle left in a hot car.

"Dioxin, a toxin that is increasingly being found in breast cancer tissue, is becoming more common." "Please be cautious and don't drink any bottled water left in your car," the post states.

USA TODAY was told by a Facebook user that he posted the message two years ago. It had been sent to him from a family member, so he decided to post it. "I didn't double-check the information, but it had thousands upon thousands of likes, comments, and shares up to 3 days ago."

An Instagram user posted the same warning on Oct. 7. It generated over 15,000 likes in just one day. The post was apparently removed.

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However, this claim is not true. The heat reacts with the plastic bottle to release chemicals, a process called "leaching". Experts say dioxin is not among those chemicals.

USA TODAY reached out via social media to those who shared the post and left comments.

Water bottles are free from dioxins

Experts say that dioxins aren't found in plastic.

According to the Environmental Protection Agency, dioxins are toxic chemicals that have certain biological characteristics and chemical structures.

According to the EPA, they are formed by industrial activity and combustion processes like burning fuel or trash. They then move from the air into soil and lakes.

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"People shouldn't be worried about carcinogenic dioxins found in drinking containers. Rolf Halden from Arizona State University, who is the director of Center for Environmental Health Engineering, said that there are other chemicals which could cause harm. "It is therefore better to store inert materials, such as glass, than plastic.

Halden disproved a similar urban myth with the Johns Hopkins Bloomberg School of Public Health, which claimed that freezing water bottles released dioxins.

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Our food system is the main source of dioxin exposure. According to USA TODAY, dioxins are industrial pollutants which persist in the environment. They tend to build up in animal fatty tissue." Nicole Deziel, an associate professor of epidemiology at Yale School of Public Health told USA TODAY. Consuming animal products such as meat, dairy and fish is one way people are exposed to these chemicals.

She stated that dioxins can cause cancer throughout the body. Breast cancer is a particular concern.

Plastic water bottles that have been exposed to heat are subject to 'leaching.

According to Halden, plastic water bottles can leach chemicals into water. The process is made easier by heat.

USA TODAY was told by he that the higher the temperature, the easier it is for things to transfer from the plastic polymer to the water in the plastic container.

According to Halden, the type of water bottle will determine what chemicals are released. The reusable polycarbonate plastic water bottles contain bisphenol A. This chemical has been shown to have adverse health effects in animals and can be used as a hormone mimic or as a fattening agent.

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The common use of polyethylene terephthalate for single-use disposable plastic bottles is well known. It is known that it can leach antimony, a dangerous metal, into the plastic, which can lead to heart, stomach, and lung problems.

Comments of Nature of Crows unclear

USA TODAY could not find any evidence that Crow spoke about plastic bottles, dioxin, and breast cancer on the Ellen Degeneres Show.

Crow conducted a 2008 interview with DeGeneres, which was posted to YouTube. However, it does not show Crow discussing plastic water bottles and dioxin. Crow was also a guest host on the show in 2006. USA TODAY couldn't find a recording of her interview to confirm what she said.

USA TODAY reached out to Crow for comment but she did not respond.

Crow wrote a 2006 post on bottled water that she posted to her website. She stated, "Don’t drink water from a bottle left in your car." Heated plastic can bleed toxic substances which could be carcinogenic.

Our rating: Partly False

Our research shows that the claim that heat reacts to plastic water bottles can be rated PARTLY FALSE. This is because it releases dangerous dioxin. Experts have found that plastic water bottles left in hot cars don't release dioxin. However, they are more likely to leak other chemicals.

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This article first appeared on USA TODAY. Fact Check: Plastic water bottles leach chemicals but not dioxins