 
Left-over food is often kept in the fridge in containers covered with plastic food wrap, and then reheated in the microwave. You may heard that this is dangerous ... that the plastic wrap or the plastic containers themselves harbour cancer-causing toxic substances such as dioxins and plasticizers, which can escape as they are being heated and get into your food. Is there any truth in this? Of course, you want to make sure that plastic wrap doesn't touch the food as it is being heated, especially if the food is high in fat. The food can get hot enough to melt the plastic, and melted plastic in your food won't taste very good. As for dangerous chemicals in the plastic, that's a little more complicated. But the simple answer is ... there aren't any ... as far as we know! Some plastic wraps made from polyvinyl chloride (PVC) do contain di[ethylhexyl]adipate [DEHA] as a plasticizer, which makes them soft and pliable. However, DEHA is not a known carcinogen ... and it's only used in commercial food wraps. The plastic films you buy in the store to cover food (such as Glad or Saran Wraps) don't even contain DEHA. Glad Wrap is made from polyethylene, and doesn't contain a plasticizer. Saran Wrap is made from acetyltributyl citrate, which is derived from citric acid. For plastics to release dioxins, the plastic must contain chlorine, and it must be heated to incineration temperatures. Not only do microwaves not heat things to that temperature, but the plastics used in kitchenware, including such things as margarine tubs, do not contain chlorine. They're generally made from polyethylene or polypropylene. Plastic containers from fast food restaurants are also made from polypropylene. Neither of these substances contain chlorine. Containers made from PVC do contain chlorine, but microwave-safe vessels aren't made from this, and a microwave couldn't get them hot enough to release chlorine anyway. As far as safety is concerned, all you need to watch out for is whether or not the container will melt in a microwave. (The melted plastic may burn you, and will not be pleasant to eat!) Margarine tubs may melt, and shouldn't be used. Any product marked 'microwave-safe' won't be made from PVC, won't melt ... and won't release any known carcinogens ... as far as we know. Having said all that, those of you who are natural pessimists may realize that just because a product has been deemed safe by government regulatory agencies, and its chemical composition determined to be non-carcinogenic, does not necessarily mean that it is safe. Our food is full of chemicals that don't appear harmful in the short term. In other words, eating them appears to pose no risk to our health. But what we don't know are the long-term risks of ingesting these chemicals. Long-term exposure to a chemical (say over 30 years) may in fact have health consequences of which we are unaware. The problem is that it is very difficult to discover the long-term effects of any chemical that is ingested regularly, let alone occasionally. Moreover, our environment, including the food we eat, is so full of chemicals, the long-term effects about which we know very little, that there isn't much we can do about it. |