Caution When Hot

An e-mail spread rumors that heating plastics leaks toxins but some scientists say it’s a hoax. Who’s right?

Story by Agatha Lutoborski

A trip to Wegmans ends with a cart full of goodies, but notice how everything is packaged. The bread loaf stays fresh in a plastic bag, a frozen dinner remains sealed in a plastic tray, and yogurt comes in plastic cups. Plastic is everywhere. It is the easiest and most common way to store food, but it might not be the safest.

An e-mail hoax from an unknown source has been circulating since 2004 stating that a Johns Hopkins University study showed that when plastics used for food storage were heated or frozen, they released harmful chemicals into the food. If eaten, these chemicals were said to cause harmful effects on humans, such as cancer and interrupted hormone circulation through the body. JHU denied the rumors, but consumers still question whether their Gladware is hurting them. Senior Jack Verhoeven heard of the e-mail and believed it. “I’m not surprised,” he says.

“Plastic is made out of gas.” As a result of this news, Verhoeven changed his habits and now moves food from plastic containers to glass and ceramic plates for microwaving.

Verhoeven’s reaction was prudent because although these e-mails are vastly exaggerated, they are not completely without scientific basis. Because of pollution, production, and incorrect product use, exposure to toxins from plastics is possible, but the chances are small. So don’t worry — cancer is not a direct result of heating up last night’s mac and cheese. It’s all in the production

“Synthetic plastics are made from very small molecules called monomers,” says Israel Cabasso, professor of chemistry and director of the Polymer Research Institute at the State University of New York College of Environmental Science and Forestry. “In a chemical reaction, the monomers are chained together, like a necklace.”

Many of these chains are plastics. In order to form the chains, however, very active catalysts are added in small quantities to spur the chemical reaction. These catalysts are additive, such as plasticizers. Plasticizers alter plastic’s performance to be, for example, softer and more pliable, says George Martin, a professor in Syracuse University’s department of biomedical and chemical engineering.

Cabasso says the danger in plastics occurs when additives like plasticizers and other chemicals, as well as toxic residue, are not properly cleaned off the new plastic during the manufacturing process.

Therefore, after the plastic is manufactured, minor amounts of the harmful substances used in production might still be present on it. These harmful chemicals are ingested if they are still on the plastic after manufacturing and the food comes into contact with it, Cabasso says. The Food and Drug Administration monitors what types of chemicals are left on plastics after the manufacturing process and how toxic they are before approving certain plastics for commercial use, according to a 2002 article from the FDA consumer magazine. This keeps occurrences of contamination low.

Myth Debunking
There is a chance that chemicals will get into food from plastics because of imperfect production and those pesky monomers and additives that react with heat. “It’s better not to use plastic in the microwave, unless it’s written that they are safe to use in the microwave,” Cabasso says. Look for the phrase “microwave safe” or a symbol of heat waves. This means the FDA has approved the plastic’s potential levels of chemical transfer for human use. Always follow directions on the packaging and only microwave what is explicitly noted to be microwave safe.
But plastic containers aren’t the only kind of plastic used in the microwave. Microwave-safe plastic wrap is another popular product t used in microwave cooking and reheating. On its Web site, the FDA advises consumers to avoid letting the plastic wrap directly touch the food while heating.
Though there is the possibility of chemicals getting into food from heated plastics, there is little danger of food getting contaminated from colder temperatures because plastic is a low-temperature material, Cabasso says. This means that the chemical structure of plastic, though it can withstand heat, is more stable and unchangeable in cooler temperatures. “Better to put [plastic] in the refrigerator than put it in the microwave,” he says.

Know Your Plastics
Some plastics are better for certain uses, and some plastics are just generally safer than others since they do not contain certain harmful additives. Start looking at the recycling symbols on the bottom of plastic containers in the refrigerator and learn which types are better. According to The Green Guide, a magazine about green living published by National Geographic, Numbers 1, 2, 4, and 5 plastics have no known hazards, so they are the best for food storage. For example, Ziploc bags are number 4 plastics, so feel free to use them. However, numbers 3, 6, and 7 plastics are more problematic. Number 3 is made from polyvinylchloride (PVC) — think white pipes used for construction — with some plasticizers added. Most cling wraps are made from this as well. To avoid the suspected transfer of DEHA, a chemical that can interrupt hormone activity in the body, take out wrapped cheeses and meats and instead store them in a glass or ceramic container as The Green Guide suggests.
Number 6 plastics contain styrene, which has not been proven good or bad, but don’t eat fatty foods that were stored in this variety because fat is more likely to soak up any stray chemicals. Some plastic knives, forks, and spoons are made from this, as well as Styrofoam containers according to The Green Guide. Number 7 plastics might be familiar to Nalgene water bottle users, but it is also the material of baby bottles and larger plastic containers like two-gallon Rubbermaids. This plastic is made from polycarbonates, which makes it heat and shatter resistant, according to the American Chemistry Council. Number 7 plastics are designated for infant use due to this heat resistant nature since baby bottles need to be reheated all the time. Bisphenol A (BPA), another hormone disruptor, is found in this type of plastic, but a 2006 study done by the Japan National Institute of Advanced Industrial Science and Technology shows moderate levels of BPA in daily life are not enough to pose severe health risks.

Have No Fear
At this point though, there is no reason for plastic-induced consumer panic. The chances of chemicals leaking into food really depend on how the plastic is manufactured, which is regulated by government agencies like the FDA. If you are not convinced, reheat and store food in ceramic or glass containers, like Verhoeven, and place paper towels without dyed patterns over it to prevent splattering when microwaving. “You don’t have to make people scared,” Cabasso says. “Everything around is plastic. It really is a very safe material.