Does Plastic in Microwave Pose Health Problems?

By Marilyn Chase
Copyright 1998 Wall Street Journal
October 12, 1998

Microwave ovens periodically ignite fears about unwanted chemicals emanating from plastic cookware or food packages.

Are they safe or not? It's not such a simple question. The explosion in food-packaging technology -- yielding a plethora of new plastics -- makes microwave safety a moving target for the U.S. Food and Drug Administration to monitor. Likewise, for health-conscious consumers.

Connoisseurs of microwave-ready popcorn and pizza got a scare several years ago when it was discovered that browning and crisping units in the packages leached low levels of benzene. The culprits were heat-concentrating elements in the packages called "susceptors," made of PET plastic bonded to aluminum with adhesive that emitted traces of the carcinogen. Manufacturers reformulated the packages, and FDA officials say it's now "a nonissue."

But consumers should stay tuned. Other modern plastics are under scrutiny, including polyvinyl chloride, polycarbonate and plasticizers --chemicals that make plastics pliable and soft. In the microwave, some chemicals may migrate into food, especially fatty food cooked at high temperatures.

Some plasticizers emit hormone-mimicking substances called endocrine disrupters, which are now being examined for potential links to birth defects, cancer or fertility problems. Though animal and population studies haven't proved causation, "they're on the radar screen," says John Brock of the Centers for Disease Control in Atlanta. And, he notes, "These compounds are ubiquitous." Plasticizers are used in everything from medical supplies and cosmetics, to toys and teething rings.

Consumer Reports recently tested plastic cookware and food wraps for endocrine disrupters. The good news was that no plasticizers were found in the Rubbermaid and Tupperware microwavable bowls tested. Plastic wraps sold for home use released only tiny traces of a plasticizer that isn't known to be an endocrine disrupter. The study did find potentially hazardous plasticizers in deli cheeses in commercial cling wrap. That leakage occurred even at cold temperatures, not just in the microwave.

IT ISN'T KNOWN how much risk resides in low-level exposure to plasticizes or chemicals in plastic ware. Still, FDA science policy analyst Catherine Bailey says "When you microwave, it's a good idea not to have the plastic touch the food." Alternatively, cook in microwaveable glass or ceramic dishes with lids, suggests Joel Tickner, a researcher and doctoral candidate studying environmental hazards at the University of Massachusetts. "I won't microwave plastic," he says.

Plastic industry groups contend plastic is safe and consumers should use common sense. "Somebody that's going to cook a steak in plastic film, they're only going to do it once," says Jerome Heckman, a lawyer for the Society of the Plastics Industry. "Not because it's unhealthy -- because it's going to be a mess."

The FDA's Ms. Bailey says the agency does what it can to monitor new plastics, but if a product is marketed as microwavable, it's up to the manufacturer to demonstrate its safety. While declaring there's no cause for alarm, she says the FDA continues to monitor microwave cookware: "If we see a material that causes concern, we'll take action on it."

The bottom line for consumers is: Not all plastic is alike, and not all name-brand plastic products are microwave-safe. Tupperware Corp. of Orlando, Fla., says that its microwaveable products are identified on the label. Those that aren't so marked could warp or melt.

Many consumers don't bother to read such labels, however. Indeed, takeout cartons, children's tableware with cartoon characters, butcher's wrap and Styrofoam meat trays are all finding their way into the microwave. "In addition to plastic migration, there's also the physical hazard of burning and scalding," says food science specialist Donald Schaffner at Rutgers University in New Brunswick, N.J.

"I know lots of people who microwave in pouches and bags that were never intended to microwave in," adds Clair Hicks, professor of food science and packaging at the University of Kentucky at Lexington.

WHILE concerned about endocrine disrupters, Prof. Hicks says he believes consumers can be reasonably confident if they cook in containers marked microwave-safe. However, he cautions, "Trust your nose, and trust your taste." If a microwaved food picks up flavor from its container, "throw it out," he says. "If you get things tasting like plastic, you're getting breakdown products."

A dash of forethought and label-reading will make microwaving safer. At a minimum, consumers should:

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