Mixing Plastic and Food: An Urban Legend?

Word about the dangers of microwaving your food in plastic containers is everywhere, but it may be time for a reality check.

Medically Reviewed by Brunilda Nazario, MD
From the WebMD Archives

Is heating food in plastic really harmful to your health?

You've probably seen or heard of the email string that's been forwarded around the Internet, warning of the dangers of throwing your food in a plastic container and popping it in the microwave. The unknown author of the foreboding email hints that a component of plastic, called dioxin, can be some pretty scary stuff. When heated, it leaches into your food and, according to the email, can cause all sorts of health problems.

Is there any merit to these claims, or is it an urban legend?


"Dioxins are unwanted byproducts of a number of processes, primarily incineration," says Rolf Halden, PhD, assistant professor in the Center for Water and Health at Johns Hopkins Bloomberg School of Public Health. "So when we burn trash, we involuntarily produce dioxins."

Resulting from the burning of things like backyard trash, waste incineration, and forest fires, dioxins can pretty much be found anywhere in the environment. Dioxins are formed as a result of combustion processes such as commercial or municipal waste incineration and from burning fuels (like wood, coal, or oil).

"Dioxins are an environmental contaminant, which means they are ubiquitous," says Halden.

And it's a vicious cycle, too: When dioxins are produced through the burning process, they are caught in the atmosphere. They come back down with rain, settle on earth, and are consumed by animals. Then, as the highest predator on the food chain, man consumes the animals, dioxins and all.

"Once dioxins enter our bodies, they like to stay in the fat tissue," says Halden. "It's a one-way route -- very little is excreted" and it breaks down very slowly.

Dioxins can cause a long list of health problems, depending on the level of exposure, when a person was exposed, and for how long and how often. According to the National Institute of Environmental Health Sciences, "Dioxin exposure at high levels in exposed chemical workers leads to an increase in cancer." The environmental agency says that based on animal studies dioxin exposure over a long period of time can lead to reproductive and developmental problems.

But the question at hand is, can the dioxins in plastic put a person at risk when heated? The answer will surprise you.

Dioxins and Plastics

The dioxins in the plastics we microwave are pretty harmless, because quite simply, they don't exist in plastic.

"There is essentially no evidence that there are dioxins in these plastic materials," says Halden.

That's right - nada -- which means when heated in the microwave, it's next to impossible for them to be released.

"You can feel perfectly confident using any plastic that is marked microwaveable in the microwave, and you and your family can use it with health and happiness," says Rob Krebs, director of communications at the American Plastics Council. "The vast majority of plastics used in food wraps and packaging containers do not contain the chemical constitutes that can form dioxins, which are a family of compounds produced by combustion at temperatures greater than 700 degrees Fahrenheit."

And if by chance you do cook your dinner to 700 degrees Fahrenheit and dioxins are leached into the food, chances are it'd be burned to a crisp and you wouldn't eat it anyway.

So now that we can cross dioxins off the list of things that keep us up at night, what else is in the plastic we heat up and eat out of that might put us at risk?

Phthalates & Bisphenol A

"If you are concerned about what happens in the microwave, you shouldn't be concerned about dioxins," says Halden. "Instead, you should consider the chemicals that actually make up plastic, which is a completely different topic."

Phthalates are chemicals that are added to many products, including plastic, that raise some questions. People are exposed to these chemicals through direct contact with products that use phthalates or food in contact with packaging that contains phthalates, says the CDC.

"Phthalates have been in plastics and have been used safely for over 40 years," says Krebs. "We believe that the amounts you would be exposed to on a normal basis have been proven safe for a number of years, and these plastics have been used by everyone from hospitals to mothers."

But while there is safety in numbers like 40 years, it's no guarantee as research continues.

"We are concerned about susceptible populations when it comes to phthalates, such as children and babies," says Halden. "A recent study suggested that there are developmental effects from boys stemming from exposure to phthalates, but this is an area that is evolving; we don't have the body of knowledge for phthalates that we have for dioxins, so we are a little bit behind on understanding the risk they pose."

Bisphenol A (BPA) is another industrial chemical that is used in plastics. It too has been around for years. According to the American Plastics Council web site, "Bisphenol A is one of the most extensively tested materials in use today. The weight of scientific evidence clearly supports the safety of BPA and provides strong reassurance that there is no basis for human health concerns from exposure to BPA."

But like most things, there is no definitive answer.

In an animal study published in the journal Endocrinology in 2004, the conclusion was, "Although there is no evidence of adverse effects in humans who consume bisphenol A orally from plastic food packaging, this exposure and the extensive use of bisphenol A in consumer products warrants more investigation of this compound at low doses for the purposes of risk assessment."

What the FDA Says

With all of these strange words being thrown around, we need the Food and Drug Administration to play big brother to food packaging companies and keep a watchful eye on their practices, and their plastic. How do they weigh in on the subject?

"Generally speaking, any food that you buy in a plastic container with directions to put it in the microwave has been tested and approved for safe use," says George Pauli, associate director of Science and Policy at the FDA's Center for Food and Safety and Applied Nutrition.

Any food packaging company that wants to put their food in plastic must pass muster with the FDA first.

"What the industry does and runs by us for approval is simulated testing to determine what could come out of the container," says Pauli. "We assume there will always be something that will leach out of the container into the food, so we look at how much someone could consume over a lifetime and compare that with what we know about the toxicity of the substance."

Basically, the FDA determines how much of a certain substance can you consume during your lifetime with little to no risk. So whether it's phthalates or bisphenol A or another chemical, the FDA's job is to make sure that the amount you're ingesting is within safe limits.

Urban Legend Debunked

The dioxin urban legend is debunked, and while the experts have slightly different opinions on phthalates and bisphenol A, they do agree on one thing: You don't need to throw out your frozen dinners or your plastic storage containers, and you should use your plastics as they're intended.

"You want to use containers for the purpose for which they were designed," says Pauli. "All testing in food safety containers is tested to be safe under the intended conditions of use. If it says suitable for microwaving, it is."

And if you slip up once in a while and throw your dinner into the microwave on a cheap plastic plate that says "Do Not Microwave," do not panic.

"Our safety evaluations are based on lifetime use, so an occasional mistake now and then doesn't need to cause panic," says Pauli. "The amounts of leaching are very small. I'm not saying it's not unhealthy, you're just going into the unknown."

As for the mass email and its unknown author, "This one was put on the Internet and the facts got mixed up," says Halden. And he agrees, "If you do use the plastics in the microwave, make sure you use materials that are approved for that purpose."

Show Sources

SOURCES: Akingbemi, B. Endocrinology, 2004; vol 145: pp 592-603. Environmental Protection Agency. Centers for Disease Control. FDA. Rolf Halden, PhD, assistant professor, Center for Water and Health, Johns Hopkins Bloomberg School of Public Health. National Institute of Environmental Health Sciences. Rob Krebs, director of communications, American Plastics Council. George Pauli, associate director of science and policy, Center for Food and Safety and Applied Nutrition.

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