Last updated on May 7th, 2024
Microwaving food in plastic containers offers convenience, but it’s essential to be able to identify safe plastic for microwave use. Heating unsafe plastics can lead not only to the container melting but also to the leaching of harmful chemicals such as BPA, phthalates, and styrene into your food. These substances are known to pose health risks, including hormonal disruptions and increased cancer risks. To safeguard your health and ensure safe food preparation, it’s important to understand the types of plastic and identify those that are microwave-safe.
The Golden Rule to Identify Safe Plastic for the Microwave
The safety of microwaving plastics largely depends on the resin identification code marked on them. These are the numbered symbols found on plastic items, usually on the bottom. Here’s what you generally need to know:
- Plastic 5 (Polypropylene, PP): The only generally safe microwave safe plastic number, you will usually be ok to microwave plastic number 5 even if it does not have a microwave safe symbol.
- Plastic 1 (PETE or PET): Avoid microwaving clear PET; however, opaque PET – known as CPET – is typically microwave safe.
Plastic Microwave Safe Symbol: A container with this symbol is designed to be used in the microwave. There is a lot of variation in its design but the common element is horizontal wavy lines one over the other. Often there will be no symbol only the words Microwave Safe. - Food Safe: It’s also worthwhile checking that the container is food safe by looking for a cup and fork symbol, indicating it is certified for food use. Alternatively, it may be explicitly labeled as “food safe,” with no symbol.
Most other plastics fall into a risky category when it comes to microwaving and are best avoided.
Is Plastic 1 Microwave Safe?
Plastic 1, or PETE (Polyethylene Terephthalate), is commonly used in the manufacturing of soft drink bottles and cooking oil containers. It is important to differentiate between CPET and APET:
- APET (Amorphous PET): Transparent and used for cold food and drink. APET is not microwave safe as it may leach chemicals or melt.
- CPET (Crystalline PET): Opaque and engineered for higher heat tolerance, making it suitable for microwave and oven use. This type is often used in ready-to-cook meal trays that are designed to withstand cooking temperatures.
Examples: Clear PET bottles are typically APET, while some frozen dinner trays and take-out containers are made of CPET.
Is Plastic 2 Microwave Safe?
Number 2 plastic is not microwave safe. Plastic 2, HDPE (High-Density Polyethylene), is used for its strength and resistance to moisture. HDPE is not typically recommended for microwave use as it can melt or deform.
Examples: Milk jugs, laundry detergent bottles.
Is Plastic 3 Microwave Safe?
Plastic 3, PVC (Polyvinyl Chloride), contains phthalates which can leach into food upon heating. It is perhaps the least safe plastic to microwave easily leaching BPA and phthalates. Beware of commercial cling film which is often still made with PVC.
Examples: Food wrap, cooking oil bottles, and plumbing materials.
Is Plastic 4 Microwave Safe?
Number 4 plastic is sort of, not really, microwave safe. Plastic 4, LDPE (Low-Density Polyethylene), is often used in grocery bags and most cling film you would find available at your supermarket and PVC alternatives. While it is safer than some other plastics, it is not typically recommended for microwave use as it can melt at higher temperatures. It could better be described as microwave resistant rather than microwave safe.
Examples: Bread bags, freezer bags, PVC free cling wrap.
Is Plastic 5 Microwave Safe?
Number 5 plastic is microwave safe. Polypropylene, marked as Plastic 5, is the only inherently microwave safe plastic. It has a high heat tolerance and does not melt or leach chemicals easily under microwave conditions.
Examples: Yogurt containers, microwaveable meal trays, reusable microwave containers, single use takeaway containers.
Is Plastic 6 Microwave Safe?
Number 6 plastic is not microwave safe. Plastic 6, PS (Polystyrene), is commonly used in disposable coffee cups and take-out food containers. It can leach styrene’s when heated, a possible carcinogen. However, it is important to note that there are specially formulated types of polystyrene that are engineered to withstand higher temperatures and can be labelled microwave safe. Typical polystyrene containers, like those used for take-out food or coffee cups, are generally not recommended for microwave use unless explicitly labelled as microwave safe.
Examples: Disposable coffee cups, take-out food containers.
Is Plastic 7 Microwave Safe?
Number 7 plastic is not microwave safe. Plastic 7 is a catch all category for various types of plastics including bioplastics which do not fit into the other six categories, including bioplastics and polycarbonate. Many of these, especially polycarbonate, can leach BPA when heated and are not recommended for microwave use.
Examples: Some reusable water bottles, certain food containers.
Conclusion
Choosing the right type of plastic for microwave use can prevent health risks and maintain food safety. When in doubt, look for the microwave-safe symbol or opt for glass or ceramic containers, which are safer and do not pose the risks associated with microwaving plastics.