Are There Any Microwave-Safe Plastics? An Essential Guide

Plastic is widely used in the kitchen for common items such as food storage containers, bottles, or cutlery due to its light weight and durability. Yet, consumers are often concerned about what can go in the microwave.

Microwave safe plastics must handle high temperatures without breaking down or releasing harmful chemicals. Plastic types #2, #4, #5, and BPA-free #7 are generally safe. In contrast, types #6 and certain cases of #7 may release harmful chemicals when heated, making them unsafe for microwave use. 

Understanding what plastics are microwave safe involves more than recognizing the types. Let’s look at what makes these plastics safe for microwave use, as well as how to visually identify which plastics are microwave safe.

Not all plastics are microwave safe, so it is important to know how to identify which ones are. Each type of plastic has a different chemical makeup, which affects how much heat it can handle. Plastic types #2, #4, and #5 are generally microwave safe, while plastic types #6 and #7 are not. As a general guideline, it is always best to look for the “microwave safe” label on containers before use. This label signifies that the container has been tested by the manufacturer per FDA standards to be safe for microwave use.

Even though microwave safe plastics are tested for safety, heat can still cause small amounts of chemicals to be released from the plastic. Being considered microwave safe simply means these amounts are low enough to meet FDA standards.

Plastic is made up of a mixture of complex chemical chains called polymers. Other chemicals are added to this mixture to help the plastic hold its shape and resist damage from everyday use. When unsafe plastic is heated in the microwave, the polymer chains can break down faster, causing the material to weaken and leach chemicals into the microwaved contents. Microwave safe plastic should be able to withstand the high temperatures within a microwave without deforming or leaching potentially dangerous chemicals. In order to be considered microwave safe, containers must go through strict testing to meet FDA guidelines. 

There are five types of plastic considered to be microwave safe. While these plastics are generally deemed safe, it is always best to follow recommended guidelines for each container.

HDPE has a high heat tolerance, making it a safe choice for microwave use. It is often used for items such as food storage containers and plastic bottles.

LDPE has a moderate heat tolerance, meaning it can only tolerate microwave heat for a short period of time. LDPE can be found in frozen food bags or cling wrap.

PP has a high melting point, making it safe for microwave use. Its durability and versatility make it a popular choice for items such as meal prep containers or reusable storage containers.

PC requires caution when determining if it is microwave safe. It has a high heat tolerance, meaning it will not deform. However, PC plastics can be made with bisphenol A, or BPA. This chemical poses health risks, and should be avoided in the microwave. To ensure safety, only use PC containers labeled as BPA-free and microwave safe.

In recent years, there have been many eco-friendly products created within the food industry. Sugarcane bagasse is a popular choice for disposable tableware, and can be capable of withstanding microwave heat. Bamboo fiber can also withstand heat, but requires some caution with manufacturer recommendations. Molded fiber products have become increasingly popular for disposable food services, and are often intentionally engineered to be microwave-safe.

Some plastics should not be used in the microwave due to the possibility of releasing harmful chemicals when heated. Polystyrene and polycarbonate containing BPA fall into this category.

Polystyrene can take multiple forms, from rigid plastic to polystyrene foam, also known as Styrofoam. Because this plastic has a low melting point, it can easily warp at moderate temperatures and may release harmful chemicals, making it unsafe for microwave use.

Polycarbonate is traditionally made with BPA. PC made with BPA risks chemical leaching, making it potentially unsafe for products such as utensils and baby bottles. Because of this, only PC plastics marked as BPA-free are microwave safe.

If a container does not have a “microwave safe” label, that means it has not been tested for microwave use. This means it could melt, warp, or release harmful chemicals when heated. It is always best to choose containers with this label to ensure safety. Additionally, it is important to know where to look for a microwave safe label. 

While there is no universal symbol to identify what plastic is microwave safe, the most common symbol is three wavy lines. Some variations will also include these lines paired with an outline of a dish or microwave. In other instances, the phrase “microwave safe” may be embossed on the underside of the container. When in doubt, contact the manufacturer.

No, BPA-free is not the same as microwave-safe. The term “BPA-free” means that the plastic was made without bisphenol A, or BPA. Microwave safe plastics are very likely made without BPA, since food packing industries understand the dangers of BPA, especially when heated. However, a BPA-free plastic container is not inherently microwave safe. 

All plastic types outside of plastic type #3 and #7 are generally BPA-free. But polystyrene, for example, is made without BPA yet cannot handle high temperatures, making it unsafe for microwave use.

At The Cary Company, we understand the importance of choosing the right kind of packaging for your product. With a wide selection of containers made from microwave safe plastics such as PP, HDPE, and LDPE, Cary's experts can help find the perfect container for your product’s needs. 

Still uncertain on how to know if plastic is microwave safe? Contact one of our product specialists at 630-629-6600, or email us at sales@thecarycompany.com.