The perils of plastic: your cling wrap could be leaching chemicals.

Open the refrigerator in a typical American home and you'll find milk, orange juice and plenty of plastic. Every day, we reach for individually wrapped cheese slices, dip spoons into plastic yogurt cups and offer babies sips of milk from plastic bottles.

If used with common sense, plastics and food can be a safe combination, experts say. But certain types of plastic are made with chemicals that may cause health problems if they leach into food. For example, meat defrosting in the microwave could pick up chemicals from a styrofoam tray that starts to melt from the high heat.

Beware of Plasticizers 

In general, the more flexible the plastic, the more likely it is to contain plasticizers called phthalates, which make it more pliable. While some phthalates are harmless, others may cause cancer. Clear rigid plastic made of polycarbonate (used to make baby bottles) also may leak the hormone-disrupting chemical bisphenol A.

So think twice before heating that takeout container in the microwave, says Suzanne Snedeker, associate director of the Breast Cancer and Environmental Risk Factors (BCERF) Program at Cornell University. Plasticizers can leach into food at high temperatures, Snedeker explains. "Some plasticizers can mimic the effects of certain hormones--they're chemical messengers in the body," she says.

Bisphenol A, used in rigid polycarbonate plastics, mimics estrogen, which is known to affect breast cancer risk. Bisphenol A is also found in plastic cutlery, water bottles, tooth fillings and the plastic coating inside canned fruits and vegetables. Animal experiments have linked bishphenol A to an increased risk for breast and prostate cancer, low sperm counts and female infertility at very low levels of exposure.

Environmental health advocates from Greenpeace, Friends of the Earth and the National Environmental Trust are calling on the U.S. Food and Drug Administration (FDA) to keep chemicals like bisphenol A out of food containers, particularly baby bottles. Environmental groups also want the FDA to require companies to disclose the use of phthalates and compounds that mimic hormones on plastic container labels.

"We should be attempting to minimize our exposure to these things," says Tom Natan, a toxicologist and research director of the National Environmental Trust. "In order to do that, we have to know they are there."

Industry Assurance

So far, the FDA and representatives from the plastics industry have resisted these requests, arguing compounds like bisphenol A do not leach out of plastic containers at high-enough levels to pose any health threat. We did a ton of testing and supplied our results to the FDA, says Jerome Heckman, general counsel for the Society of the Plastics Industry (SPI). "They are satisfied it is not a problem." But other scientists and environmental groups say the FDA needs to take a closer look at bisphenol A. For example, Frederick vomSaal, a University of Missouri biologist, says the FDA should use independent studies instead of industry data for its analysis of the health risks associated with bisphenol A.

Data from bisphenol A animal studies are significant, vomSaal says. So far, about 50 research papers have shown harmful effects--everything from an increased risk for diabetes to deformed genitals ha males. "It has been shown in birds, mammals, frogs, fish, flies and snails," vomSaal says. "The reproductive system of every type of animal is damaged by this chemical in incredibly similar ways."

The FDA has not yet required labels on plastic containers, but some companies are taking steps to reassure customers their products are safe. For example, the Clorox Company, which makes Glad cling wrap and plastic containers, says none of its products contain harmful phthalates. Instead, the company uses a safer type of plastic--polyethylene--that does not require additives for flexibility.

Clorox spokesperson Jennifer Barn hart says consumers are too quick to assume all plastic wrap brands are identical. And contrary to an incorrect e-mail that has been circulating, she says, cling wraps do not leach dioxin. "The bottom line is not all plastics are the same," she says.

Another popular brand, Saran Original, contains chlorine and plasticizers, but not phthalates, according to manufacturer S.C. Johnson & Sons. The company points to a Harvard research study that shows the plasticizer used--acetyl tributyl citrate (ATBC)--does not cause any health problems.

Gerber executives did not respond to questions about the contents of their plastic baby bottles. A call to its consumer hotline reveals that its clear plastic bottles are made of polycarbonate. A customer service employee said the company will not take them off the market or mention polycarbonate on the label until the FDA requires it.

Due to negative publicity about phthalates, plastic wrap manufacturers are now using a new class of plasticizers called adipates, says Ted Schettler, science director of the Science and Environmental Health Network. "We don't know as much about adipates as we do about phthalates because they haven't been studied as carefully yet," Schettler says.

Recommendations

Until scientists, industry and government regulators settle their debates over the issue, and until manufacturers start including ingredients on their labels, shoppers will be left in the dark about plastic food products, Schettler says. To help consumers make safe decisions, Schettler and other environmental health experts shared these common-sense tips:

* Only buy plastic wrap labeled "microwave safe" and keep it an inch or two above food when heating. In general, wraps made of polyethylene are safer than polyvinyl chloride (PVC) film.

* Use non-plastic coverings to prevent splattering, such as a glass or ceramic lid, wax paper or a cloth napkin.

* Flexible margarine tubs or whipped topping containers will warp or melt and leach chemicals in the microwave. Only use plastic containers labeled "microwave safe." Avoid PVC containers marked with the #3. Polycarbonate containers are marked with #7. Polyethylene terephthalate (PET) #1, polypropylene #5 and high density polyethylene (HPDE) #2 are less likely to have harmful additives.

* Opt for glass or ceramic bowls and plates designed for microwave use instead of plastic containers.

* Call the manufacturer to find out if your dear, hard plastic baby bottles are made of polycarbonate. If they have been repeatedly boiled or washed in the dishwasher more than 20 times, or are badly scratched, throw them out.

* Do not put polycarbonate bottles in the microwave to warm milk or formula, as this could cause bisphenol A to leak into the liquid.

* To be safe, trade polycarbonate bottles for colored or opaque bottles made of safer plastics such as polyethylene. Evenflo also makes shatter-resistant glass baby bottles.

With all of the uncertainty surrounding the safety of plastic containers, some consumers feel they are better off avoiding them. "Most people feel if a product is on the shelf it has been thoroughly tested--but that simply is not the case," Schettler says. "Given that political reality, why not try to find safer alternatives?" CONTACT: Science and Environmental Health Network, [phone], www.sehn.org; USDA Food Safety and Inspection Service, [phone], www.fsis.usda.gov.

MELISSA KNOPPER is a Colorado-based freelance writer.