Here is the short answer: Yes and No.
The problem is that not all plastics heat the same nor are they made to be heated in the microwave. Before you go to warm up last night’s dinner in the microwave, be sure its in microwavable container. But why? Why can’t I microwave food in any plastic container?
The Problem with Heating Plastic In The Microwave
There is a valid concern to make sure the foods you consumed that were cooked in a microwave using a plastic container are safe. If the plastic was not built to handle microwave radiation then the food you are cooking can absorb chemicals from the plastic. This more common with more fatty foods, but who wants to take that chance? This is one reason why you never want to buy plastics with BPA which has been shown to cause cancer. As a former stage-4 cancer survivor this is a big no no for me.
Tupperware was founded in 1948 by Earl Silas, in 1949 they introduced the Wonderlier Bowl. This was way before the microwave as we know it was first available to the public. It’s doubtful that your grandmas old Tupperware can safely be used in the microwave.
I remember growing up watching my mom go to Tupperware parties, coming home with arm full of new containers and having nowhere to put them. Needless to say, I did get a few hand me downs when I left the house that are now sitting in my covered. They are not as old as grandmas plastic containers, most of them are within 20 years old. Are they microwave safe?
Is My Ziploc or Tupperware Container Microwave Safe?
The simplest way to find out if your container is microwave safe is by looking at the package the container came in. But if you are like me and have older “hand me down” plastic containers, its best to try the next option.
Your Best Bet
If you have an old Ziploc or Tupperware container and no longer have the original packaging, or if you are not sure, look on the bottom of the container. Along with the ‘dishwasher safe” information, it should also specify if your container can be used in a microwave. You will either see something like “Microwave Oven Safe” or the microwave symbol of 3 wavy lines. If you do not see this, then do not use this container in a microwave. Consider it unsafe and I would even go as far to throw it away to make sure an ‘accidental’ nuking never occurs.
If you’re using a one-time container, you’re better off tossing it to be safe.
What happens when you try to microwave something that is not designed to be microwaved? Besides the fireworks show or melting plastic, chemicals that are meant to stay in the plastic can sometime seep into the food which has harmful effects on your health. It is not that difficult to tell which Ziploc Tupperware microwave safe once you know what to look for.