Dangers of Freezing Plastic Water Bottles

Fact Checked

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Rumors disguised as fact have been rampant in recent years that freezing water in plastic bottles poses a health danger. It turns out that freezing water in plastic bottles may be one of the safer things to do with plastic.


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In recent years there has been an email circulating throughout the Internet that claims freezing water in plastic bottles causes the release of dioxin into the water, dioxin being a toxic substance. To add credibility to this statement, it was said that the information came from research at Johns Hopkins University.

Johns Hopkins University has no research that resulted in such findings, nor did the university ever release such a statement.

A statement by Dr. Kellogg Schwab, associate professor and director of Johns Hopkins University's Center for Water and Health, says that the statement is totally untrue. Plastic does not contain dioxin. Dioxin is a chemical that, if present, is released during combustion. Dr. Schwab further explains that if anything, freezing would make any chemicals in the plastic more resistant to leaching into the water, as freezing slows the diffusion process of chemicals.


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While there is no truth to dioxin leaching into water frozen in plastic bottles, there is another area of concern with plastic, but it has nothing to do with the process of freezing. Researchers are studying the effects of another chemical in many plastics, called bisphenol A (BPA).

Dr. Lynn Goldman, a professor at Johns Hopkins University's Bloomberg School of Public Health's Department of Environmental Health Sciences, explains that bisphenol A is one of the most widely produced man-made substances globally, with more than six billion pounds produced annually.

The concern among scientists is whether BPA in plastics gets into the food and liquid it touches, particularly when heated, and if so, what are the ramifications to humans?


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Testing done in animals has shown that exposure to bisphenol A has resulted in some brain development and behavior problems, as well as early onset of puberty and altered development of the prostate gland and mammary glands. This exposure occurred early in the animals' lives.

The amount of BPA exposure to the animals in these studies was similar to that to which a human being is exposed.

In 2008, the National Toxicology Program (NTP) released a report of its studies on the risk of human exposure to bisphenol A. NTP Associate Director Dr. John Bucher stated, "There remains considerable uncertainty whether the changes seen in animal studies are directly applicable to humans, and whether they would result in clear adverse health effects." (Environmental Factor, October 2008)

Dr. Bucher also reported, "Unfortunately, it is very difficult to offer advice on how the public should respond to this information."


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Dr. Goldman recommended that anyone who has concerns about the dangers of plastics for eating/cooking/bottling should refrain from using such products and choose alternatives.

Expert Insight

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Dr. Lynn Goldman also offers advice about the use of both formula and plastic for infants, since in utero and infancy are the periods of greatest sensitivity to the effects of BPA.

Dr. Goldman reminds mothers that breast feeding is still the most highly recommended form of nutrition for infants six months and younger, and that breast milk contains the least amount of BPA of all the infant feeding methods.

Powdered formula is recommended by Dr. Goldman over liquid formula, using either glass bottles or bottles free of BPA.