Which Plastics are Microwavable?

The question of which plastics are microwavable can be answered different ways, depending on what you mean by “microwavable.” If you just want to know whether a plastic container will withstand microwaving without becoming damaged or exposing you to on-the-spot injury (such as a burn), the answer is, follow the instructions on the container. However, if you want to know which plastics can be microwaved without risk of exposing you to BPA, the answer is none.

The Milwaukee Journal Sentinel, which has been investigating chemicals in consumer products in an award-winning series called “Chemical Fallout,” tested 10 food containers that are labeled “microwave safe” or are marketed for infants. All 10 products leached BPA after normal heating in the microwave or oven.

What I found especially interesting in these results is that some of the products were plastic containers with the plastic identification numbers 1, 2 and 5. Anyone who’s been following the news this past year knows that plastics with these numbers are supposed to be BPA-free. (Only #7 is said to contain BPA.)

So, how can that be?

The purpose of the plastic identification system is only to facilitate the sorting of discarded containers to aid in recycling should a recycling program be in place.

It is not intended to ensure consumers that a container actually is accepted for recycling — let alone that it is BPA-free, does not leach chemicals or is in any way safe. Indeed, the usage guidelines from The Society of the Plastics Industry (SPI), which developed the code in 1988, explicitly states that manufacturers should “[m]ake the code inconspicuous at the point of purchase so it does not influence the consumer’s buying decision.”

However, health and environmental advocates have seized on the numbers as the only way of advising the public on which plastics to avoid.

If the U.S. had adequate safety standards in place for food packaging — or even adequate labeling requirements — this wouldn’t be necessary. As it is, you really don’t know what’s in plastic containers and packages — or what might migrate from them into the food and beverages you consume.

This is why Frederick vom Saal, the University of Missouri researcher who has been studying BPA for more than a decade and oversaw the tests for the Journal Sentinel, said, “There is no such thing as safe microwaveable plastic.”

Similarly, the Environmental Working Group, which focuses on environmental health issues, especially for babies and children who are particularly vulnerable to endocrine disruptors like BPA, recommends that you never microwave plastic.


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9 Responses to Which Plastics are Microwavable?

  1. Anonymous February 19, 2009 at 11:28 am #

    Plastic containers are not dangerous to use in the microwave if they are used in accordance with the directions on their packaging or the container itself. Everybody needs to be sure to use plastics for their intended purpose and in accordance with directions. Many plastic containers are specially designed to withstand microwave temperatures. Be sure yours is one of them. The FDA does acknowledge that substances in plastics can leach into food when the plastic containers are used incorrectly. However, the FDA does not consider this to be a significant risk to humans. The FDA maintains that: “The agency has assessed migration levels of substances added to regulated plastics and has found the levels to be well within the margin of safety based on information available to the agency.”

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  2. Sheryl February 19, 2009 at 4:47 pm #

    It would have been nice if The Society for the Plastics Industry had signed the above comment so people would know that an interested party wrote it. A link to its blog is hardly sufficient identification.

    It would be great if we could put our faith in the FDA, but unfortunately, the FDA has not done its job when it comes to protecting the public from BPA. The agency has been roundly criticized by its own scientific advisory board, among others, for ignoring a mountain of evidence showing that BPA is harmful.

    In response, the FDA agreed in December to reconsider its earlier assessment that BPA in food packaging is safe. The new assessment is due out later this month. We can only hope the FDA does a better job this time.

    Journal Sentinel
    Plastics industry behind FDA research on bisphenol A, study finds

    New York Times
    F.D.A. to Reconsider Plastic Bottle Risk

    New York Times
    Well: Panel Rebukes F.D.A. on Plastic Safety

  3. Anonymous February 20, 2009 at 10:51 am #


  4. Anonymous February 20, 2009 at 3:41 pm #

    I try to avoid microwaving in plastic whenever possible. (In fact, I try to avoid my *microwave* whenever possible.) But in a family where both of us – Mom and Dad – work full-time jobs, sometimes we have to compromise. The plastics we use are from Tupperware only, and never #7 (though Tupperware does sell #7s). Our Tupperware consultant has told us, however, that plastics are NEVER meant to be microwaved on full power. They should be microwaved at 50% power only. Why is this point never made in articles?

  5. Sheryl March 12, 2009 at 5:03 am #

    I don’t believe that microwaving at 50% power will necessarily do anything to keep you safe from toxic chemicals.

    The recommendations that come from plastics companies have to do with such things as avoiding burns or warping of the cover. They have nothing to do with preventing chemicals in the container from migrating to your food.

    As to steering clear of #7 plastics, the point of my post is that some plastics OTHER THAN #7 have been shown to leach BPA.

    The safer way to microwave is in glass. Most supermarkets carry stackable glass bowls with covers that do the whole refrigerator to microwave thing — so they’re just as convenient as the Tupperware you’re using now.

  6. wakedaddy820 May 10, 2009 at 12:28 am #

    Personally, I never use a microwave oven (view link from 2nd “Anonymous” or GOOGLE “microwave destroys nutrients”) and, until I read this post and the February issue of “This Green Life” through NRDC (through which I found the link to this post), I never considered using food containers made of a material other than plastic (i.e. glass), even if it is #1, #2, or #5, which I aim to use whenever I “need” to use plastic. These articles have been an eye opener for me and I have recently purchased a stainless steel bottle after years of reusing Propel water bottles (due to the preference in the design). Old habits do in fact die hard but even more so when corporations try to cover their lies with half-truths (if that) and deceptions and people actually believe it. I believe that if five (5) minutes were spent on researching each product a person buys, at least half would be reconsidered. The convenience factor is becoming too much of an excuse anymore and I, for one, am tired of it.

  7. shasi June 19, 2009 at 3:19 am #

    Is it safe to use melamine ware which is quoted "Microwave safe" in microwave?

  8. ALAN October 25, 2011 at 8:36 am #

    Is there a easy way to tell which plastics are safe and which are not.
    It seems to take alot of time to find out. Then it is confusing for most people!!

    • Sheryl October 25, 2011 at 8:52 am #

      Yes, look for the symbol located on the container (often at the bottom) consisting of a number inside a triangle of chasing arrows. This number identifies the type of plastic for recycling purposes.

      #1, 2, 4 and 5 plastics are generally regarded as safe for use as food containers — but as this post explains, not necessarily for microwaving.

      #3, 6 and 7 are not safe.

      For a little more information, including the names of each of these plastics, see my column on plastic water bottles found here: