12 Things You Should Really Never Microwave

Popping the wrong foods, containers, or mugs in the microwave could make you sick, expose you to harmful chemicals, or even (yikes!) start a fire. Follow these tips to avoid dangerous microwave mistakes.

by Katie Askew

Hard boiled eggs

 

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Don't let Pinterest fool you: If you try to hard boil eggs in your microwave you're likely to either end up with a big mess or burned fingers! The rapid heat from the microwaves creates a lot of steam in the egg, which has nowhere to escape. Exploded egg is hard to clean up—trust us.

Meat

 

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Frozen cuts of meat are tricky to defrost in a microwave: Thinner edges start cooking while the thicker middle remains frozen. And if your microwave doesn't rotate food while cooking it, this too can lead to uneven distribution of heat, which can can allow bacteria to grow. The safest way to thaw meat is to defrost it overnight in your refrigerator, according to food safety experts at Pennsylvania State University's department of food science.

Breast milk

 

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Not only does microwaving frozen breast milk warm it unevenly, which can create scalding hot spots for sensitive little mouths, other research has found that this heating method may destroy some of breast milk's immune-boosting proteins, particularly on high power. A better bet: Nuke a mug of water, then place a bottle of breast milk in the mug to come to room temperature.

Chinese takeout containers

 

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Metal (even small amounts of metal, like the handles on those white containers) and microwaves don't mix. Or, more accurately, when they mix, they can start fires. Put the rice in a bowl to warm it up.

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Plastic containers

 

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You know you shouldn't pop plastic leftover containers in there, but you still do. Here's why that's bad: Many plastics contain estrogen-like chemicals (BPA is a well-known one) that can leach into your food when the plastic is heated. In a study published in Environmental Health Perspectives, 95 percent of 450 plastic products (such as baby bottles, zipper-top bags and containers) tested released chemicals that acted like estrogen after they were microwaved, washed in a dishwasher, or soaked in water. Even products labeled "BPA-free" released estrogen-like chemicals. Better to be safe and warm up your dinner directly on a plate.

Styrofoam containers

 

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As a type of plastic, styrofoam can release harmful chemicals into your food when heated. Dump the leftovers onto a glass dish covered with a paper towel instead.

Certain plates

 

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Do you have a lot of fancy China or metallic-trimmed bowls? Keep them far from the microwave. Even if the metallic trimming is miniscule, it may still react in the microwave, according to the USDA. If you use the microwave a lot, it’s best to invest in a plain colored glass plate for microwave use only.

Travel mugs

 

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Stainless steel mugs block the heat from warming your coffee or tea and can damage your microwave instead. If it's plastic, check the bottom of the mug to see if it's marked as microwave safe—but even if it is, you may want to reconsider.

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Nothing

 

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With no food or liquid to absorb the microwaves, the magnetron (which is what makes the microwave function) ends up absorbing the microwaves instead, which can damage your microwave and even start a fire, according to the USDA. Make sure you don't accidentally press "start" without food or drink inside.

Cups of water

 

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When plain water is heated in a microwave in a ceramic or glass container for too long, it can prevent bubbles from forming, which usually help cool the liquid down. The water becomes superheated; when you move the cup, the heat releases violently and erupts boiling water. To avoid this scalding risk, heat water only the minimum amount of time needed or heat it for longer in small cycles.

That mug you’ve had for years and years

 

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Certain mugs made before the 1960s, like old versions of Fiestaware, were glazed with materials that could give off radiation and may contain lead and other harmful heavy metals, according to Smithsonian.com. That mug you found at your neighbor's garage sale may look cute, but consider adding it to your shelf collection instead of drinking from it.

Beware of “Microwave Safe” labels

 

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The only thing a “microwave safe” label tells you is that you can microwave the container without damaging it or damaging the microwave. In fact, manufacturers aren’t even required to test their ceramics to ensure safety after heating, according to the FDA (that’s probably why you’ve burned yourself on too-hot ceramic mugs). Even though something may say it’s safe to nuke, if you've never used it before, consider heating your liquid or food on the stove and then transfer it to a bowl, plate, or mug.