Leftovers, meal prep, or an office lunch: plastic tupperware makes them all easy and convenient to pack in single portion sizes.
But is it safe to microwave last night’s pot roast directly in a tupperware container, or should you scoop it onto a plate?
Let’s find out exactly how to know if a plastic storage container is microwave-safe or not.
What are the Dangers of Microwaving Plastics?
Some plastic contains a chemical, bisphenol A (BPA), used to make it more resilient.
BPA can cause hormonal imbalances that make diseases like cancer and obesity more likely or affect estrogen and testosterone levels.
Evidence is mounting that BPA may be linked to adverse health outcomes, but so far the FDA has not banned it.
Instead, they recommend that people limit their exposure.
Increasingly, companies are moving away from BPA use due to consumer pressure.
Some BPA-containing plastics become unstable when they are heated, causing BPA to bleed into any nearby food.
To check this, a manufacturer can submit their product to a series of extensive FDA-governed tests to demonstrate that the plastic does not melt or contaminate food when put in the microwave.
If it passes the test, the product can display a “Microwave Safe” icon, which looks like three wavy lines.
Is it Safe to Put Tupperware in the Microwave?
The word “tupperware” (lowercase “t”!) applies to many brands of food storage containers.
Not all brands meet the same standards as brand-name Tupperware ®, which continues to be an industry leader.
Founded in the mid-20th century, the Tupperware ® Corporation holds 8,500 design and utility patents for kitchen devices and home products.
Since 2010, they have only sold BPA-free products.
However, like most brands, Tupperware ® makes multiple product lines, and not all of them are designed for use in the microwave.
So, it's important to check each food storage product on a case-by-case basis.
Whether you are buying brand-name Tupperware ® or one of the many other available brands of plastic storage containers on the market, to be sure the container can be used in the microwave, it must have the microwave-safe symbol.
There are storage alternatives to plastic tupperware, such as Ziploc bags, glass tupperware or Pyrex, glass containers like Mason jars, or even a metal Yeti or thermos.
Some, but not all of these other options, are microwave-safe.
Always consult the packaging and look for the microwave-safe symbol to be sure, and check out our linked articles for more detailed info.
Can I Put Tupperware Lids in the Microwave?
Using a lid when you reheat food reduces splatter, heats food more evenly, and prevents food from drying out during the reheating process.
Many tupperware lids are manufactured with the microwave in mind, boasting features such as vent caps.
Still, even microwave-safe tupperware isn’t always intended to be microwaved with the lid on.
Read the manufacturer’s safety claims about lid use; for example, text may appear that says something like, “microwave-safe without lid” or “remove seal before microwaving” indicating that the container is safe to microwave, but the lid is not.
How Long Should I Microwave My Tupperware For?
The FDA has refused to issue general guidelines about microwave time-limits for all tupperware products.
Instead, the agency recommends that product manufacturers consult with FDA on a case-by-case basis, since the chemical composition of each product is distinct.
As an example, the Tupperware ® brand manufacturer instructions clearly state that their microwave-safe products should be heated on medium power for no more than three minutes at a time.
Recommendations vary by brand and product, but guidance for other microwave-safe plastic storage products appear similar to Tupperware Brand.
Common Brands that are Microwave Safe
Name brands like Tupperware ®, Rubbermaid ®, and Snapware ® offer multiple microwave-safe options.
They all clearly mark both their packaging and the items themselves if they are intended to be put in the microwave.
With many other brands, it can be more difficult to discern.
Look for explicit microwave-safe claims in the product description, and confirm by locating the microwave-safe symbol (three wavy lines) on the container.
A Guide to Microwaving Food Safely
Microwaves are safe and well-tested appliances, but radiation injuries, burns, and chemical contamination can happen due to improper use.
The “Do’s” of Microwaving Food:
- Always follow the manufacturer’s recommended heating instructions.
- Only microwave food in microwave-safe containers.
- Make sure your container is vented in order to avoid dangerous steam build-up, and avoid vacuum seals that cause some lids to adhere dangerously.
- Remove hot food or liquids from the microwave very carefully.
The “Don’ts” of Microwaving Food
- Never use a microwave that appears to be damaged or has a broken seal.
- Never use a microwave that operates when the door is open.
- Don’t overfill your containers! Make it easy to avoid spilling hot food or liquid as you remove a container from the microwave.
- Be very careful not to superheat your water! Microwaves can heat water beyond the boiling point without causing any bubbles. Then, a slight disturbance may cause the water to suddenly explode into a violent boil, resulting in serious burns. To avoid this, add solutes such as sweetener or instant coffee before you heat the water, and always follow the manufacturer’s recommended heating instructions.
What to Do if Plastic Melts in the Microwave
If you follow guidelines for time and heat settings and use only microwave-safe plastic, your container should remain intact and safe.
However, if you reach in to grab your food and see that the container has melted or distorted in shape, here are some points to consider.
- First, stay calm and ensure the plastic is cool enough to touch.
- Once the plastic has cooled, throw away both the melted container and the food. Do not eat food from a container that has even partially melted or distorted. This is a good sign that 1) the container was not made of microwave-safe plastic or 2) the microwave settings were beyond the manufacturer’s recommended limits. In either case, the food could be contaminated.
- If necessary, use a flat, dull edge such as a dough scraper to gently peel melted plastic from microwave surfaces.
- To remove residue and any lingering smell, microwave a few tablespoons of water and white vinegar (in a microwave-safe container, of course!) then gently wipe down surfaces.
FAQs
Is BPA-Free the same as Microwave-Safe?
No; even if plastic is free of BPA, it can still be unsafe to microwave because it can melt or distort due to low temperature tolerance.
Are there Phthalates in tupperware?
Phthalates are used in some types of plastic, but they are not generally used for tupperware-style plastic food storage containers.
Conclusion
Plastic to-go containers let you preserve food and take meals on the go, but not all of them are safe to put in the microwave.
Do a little diligence to make sure you are using those containers safely before you pack up your next round of meal prep or leftovers!
Caitlin
References
American Chemistry Council. (2022, August 17). Is It Safe to Microwave Plastic? Answering Common Safety Questions About Plastics Food Packaging. Chemical Safety Facts. https://www.chemicalsafetyfacts.org/health-and-safety/is-it-safe-to-microwave-plastic-answering-common-safety-questions-about-plastics-food-packaging/
Center for Food Safety and Applied Nutrition. (2022, September 28). Guidance for Industry: Preparation of Premarket Submissions for Food Contact Substances (Chemistry Recommendations). U.S. Food and Drug Administration; FDA. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-preparation-premarket-submissions-food-contact-substances-chemistry
FDA. (2020). 5 Tips for Using Your Microwave Oven Safely. FDA. https://www.fda.gov/consumers/consumer-updates/5-tips-using-your-microwave-oven-safely
Moreira MA, André LC, Cardeal ZL. Analysis of phthalate migration to food simulants in plastic containers during microwave operations. Int J Environ Res Public Health. 2013 Dec 30;11(1):507-26. doi: 10.3390/ijerph110100507. PMID: 24380980; PMCID: PMC3924457.
Rochester JR. Bisphenol A and human health: a review of the literature. Reprod Toxicol. 2013 Dec;42:132-55. doi: 10.1016/j.reprotox.2013.08.008. Epub 2013 Aug 30. PMID: 23994667.
Wang Y, Qian H. Phthalates and Their Impacts on Human Health. Healthcare (Basel). 2021 May 18;9(5):603. doi: 10.3390/healthcare9050603. PMID: 34069956; PMCID: PMC8157593.
