The Medical Minute: Food safety -- what about all those chemicals?

February 02, 2005

By John Messmer
Penn State Family & Community Medicine
Penn State Milton S. Hershey Medical Center
Penn State College of Medicine

Glass or plastic? No, that's not the new question asked at the supermarket. Over the last two decades, there has been a large amount of negative information about toxic contamination of food with various chemicals and resulting concerns that these chemicals could induce cancer or other diseases in people.

There has been much written about the interaction of food with plastic containers and plastic food wraps. The Internet is filled with sites containing unsubstantiated concerns about the plastic molecules and additives used in the production of plastic.

Modern plastics are about a century old if counted from the development of Bakelite by Leo Baekeland. Although celluloid and casein plastic were developed earlier, most consumers' contact with plastics increased from the time of Bakelite. With the invention of polystyrene (Styrofoam), polyvinyl chloride (PVC) and polyethylene, plastics became ubiquitous. Tupperware, made of polyethylene, and Saran Wrap, composed of polyvinylidene, put plastics into our kitchens and into contact with our food.

The term "plastic" means "capable of being molded," but some plastics do not mold very well and tend to be stiff until various "plasticizers" are added. Between the plasticizers and the plastic compound itself, there has been some fear that we will be harmed by progress.

In fact, these chemicals do migrate from plastic containers and wraps when heated or when in contact with hot or acidic foods. Heating foods in soft plastic containers, such as, soft margarine tubs, may release chemicals into the food. Plastic coverings that come into contact with fatty or acidic foods also leach chemicals from the plastic. Some of the chemicals released have been shown in high concentration to cause cancer in some species of animals. Some of the plasticizers act like sex hormones in other animal species, also raising questions as to how they will affect humans. What is not clear is whether there is any harm to us from these chemicals.

The FDA has been monitoring levels of various chemicals in the general public for some time now. The levels found in humans are far below those that harm animals. To date, no evidence has been found of any harmful effect at the levels we are likely to experience. Often animals react differently than we do, so something harmful to rats may be harmless to us.

As with so much of life, this is a risk-versus-benefit question, weighing the convenience of plastic use versus the unknown, but possibly small risk from it. We are exposed to many potentially dangerous substances frequently without much concern. Consider acrylamide found in starchy foods heated above 250 degrees Fahrenheit such as, potato chips, rice and French fries. It comes from a reaction between glucose and the amino acid, asparagine in these foods. This is a carcinogen in animals and damages nerves and DNA in high concentrations. The levels in our foods appear to be low enough to be safe, but that is not known with complete certainty.

There had been some concern in the recent past about aluminum from cooking utensils and a possible association with Alzheimer's disease. At this time, it does not appear that ingested aluminum is a cause of Alzheimer's. There is no reason to throw away your aluminum cookware, anyway, since there is more aluminum ingested with some antacids than from cooking.

There are proven risks, however. Mercury is found in many fish, sometimes in toxic quantities. Some species have so much mercury, pregnant women should never eat them. One type of blowfish is considered a delicacy in Japan, but if not prepared properly is sufficiently toxic to kill the diner.

Infectious agents can be a problem is some foods. Raw and undercooked shellfish can spread cholera. E.coli can spread from improper handling and cooking of meat. Pesticide residues can remain on the outside of fruits and vegetables and in the fat of meat. An infected food-handler can spread Hepatitis A.

So, if the possibility that plastic could be a problem worries you, don't microwave in plastic containers unless they are labeled "microwave safe" or not at all if you want to avoid this potential risk entirely. Single-serve frozen dinners may be removed from the plastic dish and microwaved in a glass or ceramic dish. Store acidic foods such as orange juice in glass containers. But while trying to avoid potential dangers, individuals should be sure protect themselves and their families against known risks.

(Media Contacts)

Last Updated March 19, 2009