“Bottled water in your car is very dangerous!” it warns.
“The heat reacts with the chemicals in the plastic of the bottle which releases dioxin into the water.
“Dioxin is a chemical found in plastic which causes cancer and are highly poisonous to our bodies.”
No dioxins in plastics
Rolf Halden of the Johns Hopkins Bloomberg School of Public Health in Baltimore, US, says dioxins are “organic environmental pollutants sometimes referred to as the most toxic compounds made by mankind”.
Exposure to these poisons can cause skin disease, liver damage and cancer. But there are no dioxins in plastics, Halden says, including the plastics used to make water bottles.
He adds that people should be “more concerned about the quality of the water they are drinking rather than the container it’s coming from”.
People might buy bottled water because they don’t feel comfortable drinking tap water, Halden says, but “city water” is more regulated and monitored for quality in the US than bottled water is.
“You are more likely to suffer from the adverse effects of dehydration than from the minuscule amounts of chemical contaminants present in your water supply.”
Water bottles made with PET
Fact-checking site Snopes says that water, carbonated soft drink and fruit juice are “typically sold in bottles made from polyethylene terephthalate, also known as PET or PETE”.
The containers are meant to be disposable, single-use bottles, “although many consumers wash them and re-use them to hold drinking water or other beverages”.
The South African National Bottled Water Association (SANBWA) says that PET, a plastic resin and form of polyester, is a common packaging for food products.
SANBWA adds that “if stored appropriately still natural mineral water will keep indefinitely” in PET. The appropriate conditions for bottled water storage is “in a dark, cool, dry area away from any solvents, chemicals or any substance which has strong odours”.
SANBWA adds that “this applies especially to water in plastic bottles”.
The US Food and Drug Administration has determined that PET meets standards for food contact materials and “thus permits the use of PET in food and beverage packaging for both single use and repeated use”.
PET, the type of plastic used to make disposable water bottles, is safe.
Bacterial growth more concerning than plastic
Colin Basch, MD of South African water treatment company Process Water Technologies, said the claim in the meme was vague and did not specify what would cause the release of the chemicals: temperature, time in heat or type of plastic bottle.
But he said that there was a risk of bacteria in the contents of a bottle.
“Organic matter”, such as bacteria, tended to grow when heated. This “would attract viruses: pathogens will attach to such organics and could evolve rapidly,” said Basch.
Once you’ve opened a bottle, there is the risk that “airborne pathogens and bacteria” might enter, which could cause harm.
“Therefore, an opened bottle left in the car would be subject to bacterial growth over time,” Basch said. – Taryn Willows
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