Imagine that you are staring at last night’s leftovers that you stored in plastic containers and wondering, “Can you microwave plastic?” You just want to get dinner on the table, but you do not want to compromise your health or safety in the process. You know that plastic is common. Everything from cutlery to serving utensils to storage containers now come in a plastic version. However, you know that plastic easily melts or warps, so you are unsure what to do. In this article, we will discuss whether it is safe to microwave plastic when you need to heat food.


Can plastic be microwaved?

When it comes to microwaving plastic and whether that is safe to do, the answer is that it depends. Microwave safe plastic does exist. However, not all types of plastic can or should be microwaved. There are serious health hazards associated with microwaving the wrong type of plastic container.

Plastics are synthetic and made with a wide array of polymers. Plastic products can be made with nylon, polypropylene, PVC, and more. These variations make it impossible to give a definitive answer to whether it is safe or harmful to place the container in the microwave.

However, when plastics melt once they are heated past a certain point, they could potentially leach harmful chemicals into the food or liquid contained within the plastic container.


Concerns with microwaving plastics

The chemical composition of the plastic containers effects whether it should be microwaved or not, as not all plastic materials are the same.



Certain chemicals that can be found in some plastic containers can be harmful to the human body. Of particular concern are BPA and phthalates. These chemicals have been shown to disrupt hormones. They are also endocrine disruptors. Both of these chemicals have been found to impact a person’s estrogen or testosterone levels, which affects the individual’s metabolism and reproductive system.

BPA can cause hormonal imbalances and can even lead to cancer. It has also been shown to increase the amount of insulin produced in the body, which leads to a slower breakdown of sugar and fat which can cause obesity.


BPA leaks

One potential problem with microwaving plastic is having BPA leak into your food. This is why it is important to look for BPA free plastic food containers to safely store your food. As the BPA free name suggests, this type of plastic does not contain BPA and is generally considered to be more consumer friendly.

Heating up a plastic container that contains BPA increases the likelihood that the BPA seeps into the food, especially when exposed to high heat levels. The heat of the microwave breaks down the structure of the plastic. This can cause the chemicals in the plastic to seep into the foods. Heating up food in the microwave effects the durability of the container and can harm the safety of the food itself.


Microwaving plastic

Plastic is quite commonplace in this day and age. We have easy access to everything from plastic serving utensils to plastic cutlery. Given its prevalence and cheap cost, it is no surprise that plastic storage containers abound. Not only is plastic cheap and relatively durable, but it is also very convenient to use. Tossing leftovers in plastic containers is easy to do so that the food can be placed in the refrigerator and enjoyed later. However, not all containers are created equal. For example, when plastic is exposed to high levels of heat, it can melt and start to break down.

Plasticizers, or the substances that give the plastic containers their shape and flexibility, can leak into your food if you microwave plastic. The most commonly used plasticizers are phthalates and bisphenol. When a plastic container undergoes high levels of heat in the microwave oven, it begins to melt. Then, the softened plasticizers can come into contact with the food or liquid being warmed up in the plastic container.

This can cause health ramifications like those mentioned previously. This is why it is important to be cautious when microwaving plastic. You want to ensure that you are using food-grade plastic, which is subject to stricter regulations. Detailed guidelines have to be followed by the manufacturers in order for their plastic product to be deemed microwave safe.


Melting plastic

You may be wondering why plastic melts in the microwave. When the plastic comes into contact with intense heat, it begins to warp or melt. Some ingredients commonly found in food, such as sugar or fat, have a boiling point that is higher than water. For this reason, meats, cheeses, and candies can warm up to very high temperatures even in the microwave. Then, they cause to plastic to melt very quickly.

In addition to the type of food being warmed up, there are also differences based on the type of plastic used to make the container. Different plastics will react to various levels of heat differently. For this reason, different plastics have differing purposes and safe uses.

If you plan to place the container in the microwave, be sure to use food-grade plastic storage containers that are designated as microwave safe. These are designed to handle higher levels of heat without warping or melting.


Containers to avoid microwaving

You do not want to microwave any container that can easily melt. While some plastics are deemed microwave safe, others are not. You should also not microwave anything with aluminum as it could short circuit the microwave and cause a fire. Paper containers are also not microwave safe. The paper will burn, catch on fire, or break. Any of these options will cause a mess and could also potentially harm the user.


Environmental health

In addition to potentially harming your own health, there are also environmental health concerns associated with heating up food containers in microwaves. The bottom of the container should have a recycling number listed in the center of a triangle.


Types of plastic

There are multiple types of plastics. Each one has different chemical composition, properties, and temperature limits. For example, Plastic #3 is PVC or polyvinyl chloride. Food containers no longer use this type of plastic because it contains BPA, a harmful chemical.

If you are curious about whether a plastic container is made of microwave safe plastic, you can check on the bottom to see if it shows a microwave image or says it is microwave safe. The FDA approved symbol is a picture of a microwave with three to five wavy lines inside of it. This represents microwave energy being used. Alternatively, some products will have the words “microwave safe” on the bottom instead of the symbol. If no guidelines are given on the bottom of the product, the plastic numbers can help you determine whether you should put the item in the microwave.


Plastic #1

This type of plastic is not microwave safe. It is primarily used for single-use food containers and it typically used with food that does not need to be microwaved, such as fruit. The plastic in this type of product is Polyethylene Terephthalate, which has a melting point of 120 degrees Fahrenheit. This type of plastic is typically deemed to be safe for one time use only.


Plastic #2

Plastic #2, or high density polyethylene (HDPE), is considered by some to be microwave safe. This type of plastic is often used to transport liquids or drinks, such as a milk container or a jug of juice. The heat limit of high density polyethylene is 266 degrees Fahrenheit. This type of plastic is durable and can be reused since the plastic will not easily wear down. However, you should be aware that there are mixed opinions about whether Plastic #2 should be used in the microwave.


Plastic #5

Polypropylene, or Plastic #5, is another type of microwave safe plastic. This type is commonly used to store food or to produce plastic forks or spoons. The melting point of Plastic #5 is 250 degrees Fahrenheit, so it can withstand the microwave oven for a reasonable about of time in order to heat up food.


Plastic #6

Plastic #6 is also known as polystyrene. This is the basic component that makes up styrofoam. This type of plastic should not be microwaved. The melting point of styrofoam is very low. Even if you do not place a plastic container made of Plastic #6 in the microwave, if you put extremely hot food in it, the container can start to melt. While this may be a popular takeout container, you should not reheat food in a plastic container made of Plastic #6. Polystyrene plastic is also not recyclable, which has led some cities to outlaw its use.


Helpful tips for microwaving food

To avoid having harmful chemicals leach into your food or risk causing a fire in the microwave, be sure to follow these helpful tips.


Use BPA-free plastic

It is important that only BPA-free plastic is used to ensure the integrity of your food. The BPA-free designation means you do not have to worry about those chemicals seeping into your food.


When in doubt, use glass or other containers

If you are unsure about the safety of microwaving plastic, transfer the food to a glass or ceramic bowl or dish instead before placing the food in the microwave oven.

Related: Can You Microwave Glass? Read this first!


Do not microwave metal

Remember that metal, including aluminum, should not go in the microwave. Even a minor metal decoration on a bowl or plate can cause a fire.


Be careful with plastic wrap

For one, not all plastic wrap is deemed to be microwave safe. If you are using plastic wrap that is, ensure that it does not directly touch the food you are reheating.


Use a lid

There are a variety of reasons why you should heat food with a cover or lid over it. For one, doing so can reduce the heating time. It will also help the food cook evenly and even keeps the moisture within the food. You do not need to have the lid completely sealed on the container. Instead, you can just place it loosely on the top or at an angle so that steam can escape. If the steam were to stay trapped inside the plastic container, it could explode.


Can you microwave plastic FAQ

How do I know if plastic is microwave safe?

Flip it over and check the bottom. There should either be the words microwave safe or a symbol of a microwave with three to five wavy lines in it.


What type of plastic is microwave safe?

According to the FDA, you should only microwave containers that are clearly labeled as safe for use in the microwave. It is also important that the plastic food containers be BPA free so that they are safe to store food or liquids. Type 5 polypropylene plastic is generally considered to be the best option.


Can plastic takeout containers be microwaved?

Generally speaking, the plastic takeout containers are made with styrofoam and should not be microwaved.

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