Johns Hopkins professor Rolf Halden talks about the myth of dioxins and plastic water bottles.
The Internet has been flooded with email warnings to avoid freezing water in plastic bottles so as not to get exposed to carcinogenic dioxins. One hoax email has been erroneously attributed to Johns Hopkins University since the spring of 2004. The Office of Communications and Public Affairs discussed the issue with Rolf Halden, PhD, PE, assistant professor in the Department of Environmental Health Sciences and the Center for Water and Health at the Johns Hopkins Bloomberg School of Public Health. We sat down with Dr. Halden to set the record straight on dioxins in the food supply and the risks associated with drinking water from plastic bottles and cooking with plastics.
Question: What do you make of this recent email warning that claims dioxins can be released by freezing water in plastic bottles?
Answer: No. This is an urban legend. There are no dioxins in plastics. In addition, freezing actually works against the release of chemicals. Chemicals do not diffuse as readily in cold temperatures, which would limit chemical release if there were dioxins in plastic, and we don’t think there are.
Question: So it’s okay for people to drink out of plastic water bottles?
Answer: First, people should be more concerned about the quality of the water they are drinking rather than the container it’s coming from. Many people do not feel comfortable drinking tap water, so they buy water in plastic bottles instead. The truth is that city water is much more highly regulated and monitored for quality. Bottled water is not. It can legally contain many things we would not tolerate in municipal drinking water.
Having said this, there is another group of chemicals, called phthalates that are sometimes added to plastics to make them flexible and less brittle. Phthalates are environmental contaminants that can exhibit hormone-like behavior by acting as endocrine disruptors in humans and animals. If you heat up plastics, you could increase the leaching of phthalates from the containers into water and food.
Question: What about cooking with plastics?
Answer: In general, whenever you heat something you increase the likelihood of pulling chemicals out. Chemicals can be released from plastic packaging materials like the kinds used in some microwave meals. Some plastic drinking straws say on the label “not for hot beverages.” Most people think the warning is because someone might be burned. If you put that plastic straw into a boiling cup of hot coffee, you basically have a hot water extraction going on, where the chemicals in the plastic straw are being extracted into your nice cup of coffee. We use the same process in the lab to extract chemicals from materials we want to analyze.
If you are cooking with plastics or using plastic utensils, the best thing to do is to follow the directions and only use plastics that are specifically meant for cooking. Inert containers are best, for example heat-resistant glass, ceramics and good old stainless steel.
This interview with Dr. Halden is an excerpt from a Johns Hopkins Medicine press release. To read the entire interview, go to http://www.jhsph.edu/publichealthnews/articles/halden_dioxins.html
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