An email has been going around about the danger of freezing plastic bottles of water. It goes something like this:

Johns Hopkins has recently sent this out in their newsletters...worth noting...
Dioxin Carcinogens cause cancer. Especially breast cancer. Don't freeze your plastic water bottles with water as this also releases dioxin in the plastic. Dr. Edward Fujimoto from Castle hospital was on a TV program explaining this health hazard. He is the manager of the Wellness Program at the hospital.

But Johns Hopkins never sent out a newsletter suggesting any such thing. And Dr. Rolf Halden, of the Johns Hopkins Bloomberg School of Public Health, has now gone on record to debunk this hoax, noting that if freezing the plastic bottle were to do anything, it would probably make the water inside safer to drink because "freezing actually works against the release of chemicals."

But heating plastic water bottles is another matter. "Halden does warn that another group of chemicals that are used to make plastic less brittle can be released if you place them in hot water or heat them in the microwave." But considering all the junk that we Americans willingly shove into our mouths, the "miniscule amounts of chemical contaminants present in your water supply" probably shouldn't be high on anyone's list of worries.