Freezing plastic bottles: Does it release dioxins?

No. This has been the subject of an e-mail hoax. An e-mail that has been circulating claims that freezing water in plastic bottles releases cancer-causing substances (carcinogens) called dioxins. Dioxins are typically formed when certain materials are burned, and there is no evidence that plastic bottles contain dioxins. So you should not worry that freezing plastic water bottles will expose you to these toxic chemicals.

If you reuse the same water bottle, be sure to wash it on a regular basis with warm, soapy water to inhibit the growth of bacteria. It's also a good idea to replace the bottle from time to time.