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What is Microwave Safe Plastic?

Kris Roudebush
Kris Roudebush

Microwave safe plastic is plastic that has been designed for use in microwaves. All of these plastics undergo testing by the Food and Drug Administration (FDA) to ensure that the plastic will retain its shape under high temperatures and have the least amount of leaching possible. Leaching is considered to be safe provided that the amount of leaching is within certain parameters for the type of plastic used.

There are many different types of microwave safe plastic. Single use containers should be thrown away after they’ve been heated up once. They are designed and approved for one use only and further usage may cause unsafe leaching into food. Single use containers are generally thought of as safe if you follow the heating instructions found on the package.

Plastics that aren't labeled as being microwave-safe should never be used in a microwave.
Plastics that aren't labeled as being microwave-safe should never be used in a microwave.

Plastic wrap that's designed for microwaving should be loosely placed over food. Be sure to follow manufacturer’s instructions as some manufacturers recommend at least an inch between the food and the plastic wrap. There is some controversy about the safety of this type of plastic wrap. The FDA indicates that as long as you follow manufacturer’s instructions you will be safe. The FDA also acknowledges that you should not use plastic wrap to heat high fat foods as this will cause a greater amount of di(ethyhexyl)adepate (DEHA) to leach into food.

Microwave safe plastic wrap should loosely cover the food being heated to minimize leaching.
Microwave safe plastic wrap should loosely cover the food being heated to minimize leaching.

DEHA is a known cancer causing chemical and is used in microwave safe plastic wrap. DEHA has also been linked to breast cancer in women and low sperm counts in men. The FDA has not yet created regulations for this chemical; however they recommend no more than 0.05 parts per billion. When using plastic wrap to heat high fat foods, as much as 500 parts per billion of DEHA can migrate into foods, according to private testing.

Plastic containers must be stamped with the microwave safe seal before they can be used in microwave.
Plastic containers must be stamped with the microwave safe seal before they can be used in microwave.

Never use plastic containers that do not indicate they are safe for the microwave. There is an international seal for microwave safe plastics. It is square with a small dish at the bottom and 5 rows of waves, above the dish, stretching across the square. If your plastic container doesn’t have this seal or have instructions for microwave use you should consider the plastic unsafe for the microwave. Not only are these containers not microwave safe and have the potential to leach plastics into your food, they may melt or warp causing spills or burns.

Plastic compresses intended for heat therapy are microwave safe.
Plastic compresses intended for heat therapy are microwave safe.

To ensure your plastics are safe in the microwave consider these tips. When choosing a plastic, to use in the microwave, be sure to read any manufacturer’s instructions carefully. If your microwave safe plastic is showing wear, consider replacing it. Toss out any single use containers once they have been used.

Discussion Comments

czechmate

How do you find out about previously manufactured plastic microwave cookware like Littonware or Anchor Hocking? I can't find any info on the web about whether these old items are safe now that we know more.

FlyFly

@bluekitchen, Only plastics that are labeled as microwave safe should be used in the microwave. When microwaving with plastic wrap, the wrap probably shouldn't come into contact with the plastic.

There is evidence that chemical components can leech into the food while being microwaved. However, it is controversial whether or not there is enough to do any damage.

If you want to cook your own potatoes at home in the microwave you could try makings some small holes with a fork to vent it. Then wrap it in damp paper towel and microwave for 3- 8 minuets (depending on size). After it sits in the microwave for a few minutes it should be ready to eat.

bluekitchen

What do you know about the plastic wrap used for Express Bake PotatOH! products? They make microwaveable russet and sweet potatoes that are tightly sealed in plastic. After microwaving the potatoes you remove the wrap. Just wondering if this kind of plastic might be available for home cooks?

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    • Plastics that aren't labeled as being microwave-safe should never be used in a microwave.
      By: trekandphoto
      Plastics that aren't labeled as being microwave-safe should never be used in a microwave.
    • Microwave safe plastic wrap should loosely cover the food being heated to minimize leaching.
      By: Coprid
      Microwave safe plastic wrap should loosely cover the food being heated to minimize leaching.
    • Plastic containers must be stamped with the microwave safe seal before they can be used in microwave.
      By: krasyuk
      Plastic containers must be stamped with the microwave safe seal before they can be used in microwave.
    • Plastic compresses intended for heat therapy are microwave safe.
      By: nito
      Plastic compresses intended for heat therapy are microwave safe.