Do Microwaved Plastics Cause Cancer?

Last Modified: August 21, 2005

Dear OncoLink "Ask The Experts,"
I recently received an email claiming to have information written by Johns Hopkins University about the risk of cancer from plastic. The email claims that cooking in plastic containers in the microwave, putting water bottles in the freezer, or using plastic wrap in the microwave can all cause cancer. Is there any truth to this? I am having a hard time finding information about its validity.

Carolyn Vachani RN, MSN, AOCN, OncoLink's Medical Correspondent, responds:

Thanks for your question. I have also heard this over the years, and seen these emails, so I did some research.

It seems that food safety experts agree that you should only use plastics labeled "microwave safe" to cook in the microwave, and if you use plastic wrap (like saran wrap), it should not come into contact with the food. According to the U.S. Food and Drug Administration, chemical components can indeed "migrate" from plastics into the food at microwave-level temperatures. However, there is scant evidence to date, says the agency, that such contaminants actually pose a serious threat to human health.

Dioxins (discussed in the email mentioned in your question) are toxic substances, but are not contained in plastic wrap or microwaveable plastics. The email claims that dioxins are the potentially hazardous compounds in plastic.

Di-ethylhexyladipate (DEHA) is a compound that is added to plastics to make them more pliable. It has been thought that DEHA may be carcinogenic (cancer-causing). However, the U.S. Environmental Protection Agency (EPA) removed DEHA from its list of toxic chemicals in the late 1990s after concluding, based on a review of the scientific evidence, that "it cannot reasonably be anticipated to cause cancer, teratogenic (birth defect-causing) effects, immunotoxicity, neurotoxicity, gene mutations, liver, kidney, reproductive or developmental toxicity, or other serious or irreversible chronic health effects."

As for the email itself, it is a fake. The link below will take you to the Johns Hopkins School of Public Health, which put out a press release in response to this email, addressing some of the issues – (including freezing water bottles, which it is fine to do!).

Given all this information, I think I'll be extra cautious and take the few extra seconds to put my food in a glass container before I microwave it and avoid the need for plastic wrap with a lid!