Is plastic ever safe to use in the microwave? I asked a few experts to weigh in


Microplastics It may seem like a health buzzword, but… Studies are accumulating About how much we consume daily, and the long-term health risks are still unknown.

While the microwave alone is said to be safe, placing plastic containers, plastic wrap, silicone and other polymer compounds under its hot rays can cause bigger problems.

Place a plastic-wrapped bowl in the microwave

Microwaves and plastic can be a dangerous combination. Here’s what experts tell me about the risks involved and how to avoid them.

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“Microwave-safe use not only means that the container won’t melt or warp, it also means that it won’t release or leach harmful chemicals into our food when heated,” says Li Li, an assistant professor at UCLA. University of Nevada, Reno School of Public HealthHis specialty is environmental health and exposure science.

I spoke with Lee and other materials and health experts about the dangers of exposing kitchen containers and various packaging materials to electromagnetic radiation from microwaves.

Here’s what they said.

Best practices for using containers in the microwave

A person places a plastic container in the microwave

Microwaves can leach chemicals into food from food storage containers. An expert explains how to avoid the problem altogether.

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Before we delve into the specific materials and their many variables regarding their suitability for microwave use, consider the following.

Look for microwave-safe labels just as a starting point

Microwave foam container

Styrofoam and a microwave are a dangerous combination.

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While some materials are generally safe to use in the microwave, it is still a good habit to look for a “microwave safe” label of some sort. However, keep in mind that this classification does not tell the whole story.

Similar to Expiry dates on food itemsThe microwave-safe label is not based on a federal certification program. “Manufacturers can use it if their own tests show that it meets the microwave-safe standards they have in mind. It’s a helpful guideline, but it’s not a guarantee,” Lee says.

In addition, this label does not necessarily indicate any risks to human health.

Toss out all damaged containers

Food leftovers in plastic food containers

Damaged food containers may leach chemicals into the food.

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Damaged containers can leak chemicals or toxins into your food. They may also malfunction due to the vibration of electromagnetic waves on which the microwave function depends.

Regardless of whether the container is labeled microwave safe and regardless of the material used in it, throw it away if it is not in good condition.

“If it’s scratched, punctured, cracked, or damaged in any way, you can no longer assume it’s safe to use in the microwave,” says Kelly Johnson Arbor, a toxicologist at Harvard University. MedStar Health.

Do not move from freezer to microwave

Someone takes food out of the freezer

Frozen containers, especially plastic ones, should not be placed in the microwave.

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Although transitioning from the refrigerator to the microwave is generally fine for most items, you should avoid sudden temperature changes, Lee says. Allowing a moment to place a glass or ceramic bowl on the countertop can help reduce shock once it goes into the microwave.

“Never go from the refrigerator directly to the microwave,” Lee says. “Such large temperature changes can cause cracking,” which immediately puts the food inside the container at risk.

Be careful with decorative items

Treasures Antique Store, Williamsburg, Virginia, racks of antique dishes

Old plates, bowls, and serving dishes often have decorations that are not microwave safe.

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Even if you use a microwave-safe material, be wary of overly decorated bowls or bowls.

Traditional decorative ceramics are usually fine, but “be careful with decorative coatings or metal embellishments, as they can ignite or degrade when overheated,” Lee says.

Best microwave safe options: glass and ceramic

Glass and ceramic bowls are generally safe for use in the microwave oven, according to Johnson Arbor.

“They both act as insulators, which means they are resistant to heat transfer,” she says, so the bowls themselves do not heat up, while the electromagnetic waves heat the food inside.

In addition to withstanding high heat, “glass and ceramic vessels typically do not contain organic chemical additives,” Lee says.

glass

A person opens a glass bowl with food inside

Glass containers are safe as long as the rubber or plastic lids do not come into direct contact with the food.

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While many glass storage containers have lids with a rubber or plastic element, they are generally fine as long as these elements do not come into contact with food. (But be sure to clean them well so the rubber seals don’t develop mold.)

If you’re looking for the best possible option, casseroles with glass tops and no seals are ideal containers for cooking and reheating in the microwave.

Libyan

To safely destroy food, glass is your friend.

Ceramic

Ceramic plate in the microwave

Ceramic bowls are one of the safest options for heating food in the microwave.

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Commercial ceramics are usually microwave safe and should be labeled as such, but be sure to double-check those that are more decorative or artisanal.

“The glazes found in some ceramic products can contain heavy metals, including lead,” says Johnson Arbor. “When these glass materials are heated, lead can leach out and contaminate the food or liquids in the ceramic container.”


Many ceramic food storage options also feature plastic or rubber lids, but here’s a ceramic/glass set we like, complete with silicone lids that can be used in the refrigerator or for transport, and can be replaced with glass in the microwave.

Corning ware

Ceramic food containers are usually microwave safe.

Is it safe to put plastic in the microwave?

Someone puts a takeaway container in the microwave

Because the overall impact of microplastics on our health is still unknown, some people choose to avoid using plastic food containers in microwaves altogether.

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Of course, it’s complicated.

“Many plastic food storage containers have ‘microwave safe’ labels or graphics to indicate that these products can withstand the high temperatures produced by microwaves,” says Johnson Arbor. “But in recent years, scientists have discovered that small plastic particles, called microplastics, can leach out of food storage containers when heated.”

since Microplastics In the conversation, many brands claimed to be “BPA-free” to ease consumers’ minds.

“Polycarbonate food containers are made from a group of chemicals called bisphenols,” Lee says. Bisphenol A is commonly referred to as BPA.

“BPA is known to interfere with hormones and has been linked to some endocrine disrupting effects,” he says. “Although polycarbonate can withstand virtually high temperatures, meeting manufacturers’ ‘microwave safe’ requirements, microwave heating accelerates the release of BPA, especially when the container is scratched, reused multiple times, or contains fatty or acidic foods.”

Read more: Microplastics can leach into your food if you make this simple mistake

Microwave

Experts recommend that you be careful and read product materials carefully when using plastic in the microwave.

Panasonic

According to experts, BPA-free containers are slightly better.

“Polypropylene, often called ‘PP plastic’ or labeled ‘No. 5 plastic,’ is generally a better choice,” Lee says. “It has good heat resistance and tends to contain fewer additives than other plastics. However, less does not mean none, and it still uses some chemicals such as antioxidants or stabilizers during manufacturing.”

The safest position possible? “Because the overall impact of microplastics on our health is still unknown, some people are choosing to avoid using plastic food containers altogether in microwaves,” which is the safest position, regardless of whether something is BPA-free, Johnson-Arbor says.

Plastic wrap, generally approved for use in the microwave due to its heat tolerance, It should never come into direct contact with food.


If you don’t want to give up the convenience and budget-friendly nature of BPA-free plastic storage containers (and you’re committed to taking responsible care of them and throwing them away if they get scratched), here’s the set we recommended previously.

Bentgo

Paper comes with a catch

Decorative paper plate next to plain white paper plate

Decorative and colorful paper plates should be kept out of the microwave.

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You may have several types of paper in your kitchen, including paper towels, wax paper, parchment paper, butcher paper, and even a variety of paper plates for festive occasions. Do you have to put any of it in the microwave?

“For most everyday uses, white paper towels or paper plates are generally safe to use in the microwave,” Lee says. A paper towel is a useful cover for reheating food on ceramic dishes, helping to avoid food splatters without resorting to plastic wrap.

But there is also a problem.

“You should avoid using colored or patterned paper plates in the microwave, brown grocery bags or fast food bags, and any paper plates that have a water- or oil-resistant coating,” he says. “This is because we cannot rule out the possibility that they could smoke, melt or release unwanted chemicals when heated.”

The same goes for wax paper, which can melt or decompose at high temperatures or in contact with certain types of food. If the paper product has a shiny or smooth side, it is best to avoid it as a general rule.

Metals are never microwave safe

A person dressed in black unwraps a roll of aluminum foil.

Keep all metal, including aluminum foil, out of the microwave.

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When it comes to microwave cooking, metals are unsafe for neither health nor heat tolerance reasons. Stainless steel and cast iron are excellent materials for stovetop cooking, but they cannot be microwaved due to the way microwaves work. Putting them in the microwave is counterproductive and dangerous.

“The metal reflects electromagnetic waves,” explains Johnson-Arbor, which prevents it from actually heating your food. “This may cause heat to transfer to other surfaces in the microwave, which may result in overheating or a fire.”



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