"I don't use plastic wrap in the microwave because i worry about the petroleum that they use in the manufacturing and because of the fumes that could get into the food."

Many people are concerned and confused about using plastic containers and wraps in the microwave, thanks largely to widely-circulated warnings on the Internet. As with many e-mail rumors, these have generated lots of heat without shedding much light.

One of the scariest warnings is that zapping plastic containers releases cancer-causing chemicals called dioxins.

In fact this is false.

There are no dioxins in plastic containers, nor does microwaving cause the chemicals to form.

Another claim is that substances called plasticizers, which are in wraps and containers to help make the plastic flexible, leach into food during cooking and cause harm.

It's true that small amounts can make their way into fatty foods during heating or even at cooler temperatures.

While some of these chemicals cause harm to lab animals, there's little evidence that the amounts to which we're exposed pose a risk to humans.

To be on the safe side, though, keep wrap from touching your food during microwaving. If nothing else, this will prevent plastic from melting into your meal.

Also, look for plastic containers that are labeled "microwave safe." This means they've been tested according to FDA rules and won't melt. What's more, the levels of any chemicals they release must be 100 times or more below the amount known to harm animals.

Styrofoam is fine to use as long as it's labeled microwave safe.

But be careful about takeout containers from restaurants. Most are not designed for the microwave and can melt when heated.

Ditto for plastic tubs that margarine and other foods are sold in.

Bottom line: as long as it's made for the microwave, plastic is perfectly safe to use. What we should really worry about is those misleading Internet rumors.