How Plastic Food Containers Can Make You Sick | Chris Kresser

How Plastic Food Containers Could Be Making You Fat, Infertile and Sick

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In previous articles here, here and here, I wrote about the dangers of an environmental toxin called bisphenol-A (BPA). BPA is a chemical that is found in several plastics and plastic additives. It’s in the water bottles some folks carry to gyms, the canned tomatoes and coconut milk they cook with, and in the baby bottles moms use to feed their infants.

We’ve known for decades that BPA has estrogenic activity. In vivo animal studies and in vitro cell-culture research has linked low-level estrogenic activity associated with BPA exposure to all kinds of fun stuff, like diabetes, ADHD, heart disease, infertility and cancer.

There is now significant evidence suggesting that even low levels of BPA-exposure can cause harm, and this is particularly true in vulnerable populations like pregnant women, infants and the chronically ill. (1)

Because of this research, and the growing public awareness that BPA should be avoided, a new crop of “BPA-free” plastic food containers and baby bottles has been introduced. However, a recent study published in the journal Environmental Health Perspectives in July has shown that even BPA-free plastics have chemicals with estrogenic activity (EA), and can cause serious health problems as a result. (2)

What is “estrogenic activity” (EA)?

Chemicals with estrogenic activity (EA) are those that mimic or antagonize the actions of naturally occurring estrogens. These chemicals are capable of binding with one or more of the nuclear estrogen receptors in the body.

The best way to think of chemicals with EA is as a counterfeit key fitting into a loose lock.

When these chemicals activate the estrogen receptor, they produce an increase in circulating estrogen, which in turn can cause problems such as early puberty in females, reduced sperm counts, altered function of the reproductive organs, obesity, increased rates of certain cancers and problems with infant and childhood development. (3)

As I mentioned above, vulnerable populations such as pregnant women, developing fetuses, infants and children are especially sensitive to even very low doses of chemicals with EA. (4)

BPA-free is not EA-free

In the Environmental Health Perspectives study, Yaniger et al. set out to determine the estrogenic activity of commonly used plastic consumer products.

They bought more than 500 plastic products at places like Wal-Mart, Whole Foods, Trader Joe’s, Target, and other major retailers. They selected from all categories of plastic, including tupperware containers, bags and wraps.

Then they cut the containers into pieces, put them into liquids that contain similar chemicals found in food and drinks, and subjected them to stresses that mimic normal use, like UV light (sunlight), microwaving, or moist heat (like boiling or dishwashing).

Their results showed that over 90 percent of the products leached estrogenic chemicals before they were even stressed, and after being stressed essentially all of the products showed estrogenic activity.

According to Stuart Yaniger, one of the lead authors of the study:

Baby bottles, plastic bags, plastic wrap, clamshell food containers, stand-up pouches: Just about anything you can think of that’s made of plastic that food or beverages are wrapped up in, we found this activity. It was shocking to us.

What plastics do and don’t have EA? It’s impossible to tell.

Perhaps the most troubling outcome of this study is that it’s currently impossible to determine which consumer plastic products are likely to have chemicals with EA, and which are not.

The exact chemical composition of most plastic products is proprietary and thus not known, and a single plastic item containing many parts (e.g. a baby bottle) may consist of >100 chemicals, all of which can leach from the product.

In light of the researchers’ finding that nearly all of the 500 plastic products they tested leached when stressed, and 90 percent of them leached even without stress, I think it’s pretty safe to assume that most plastic products you can buy in the store have chemicals with EA.

It’s important to reiterate that this is true even with BPA-free plastics. In fact, the Environmental Health Perspectives study found that some BPA-free products had even more EA than BPA-containing products!

Should you be concerned about chemicals with EA?

There are still a lot of unknowns in the discussion of the EA of various chemicals in plastic products, such as the number of chemicals having EA, their relative EA, their release rate under different conditions, and their half-lives in human beings of different ages.

However, there are 3 strong arguments for being “better safe than sorry” when it comes to plastics and EA (5):

  • in vitro data overwhelmingly show that exposures to chemicals with EA (even in very low doses) change the structure and function of human cell types;
  • many studies present clear cellular, molecular and systemic mechanisms by which chemicals having EA produce changes in cells, organs and behaviors; and,
  • recent epidemiological studies strongly suggest that chemicals with EA produce measurable changes in the health of various human populations.

Perhaps the study authors summed it up best in their conclusion:

Many scientists believe that it is not appropriate to bet our health and that of future generations on an assumption that known cellular effects of chemicals having EA released from most plastics will have no severe adverse health effects.

I couldn’t agree more.

What you can do to reduce your exposure to chemicals with EA

Here’s a list of things you can do to reduce your exposure – and especially your baby’s and children’s exposure – to chemicals with EA.

  • Use glass containers and canning jars at home for food storage. Be aware that the lids of Mason and Kerr brand canning jars contain BPA and chemicals with EA. There are BPA-free lids, but they still may contain chemicals with EA, and I’ve been told they’re made with formaldehyde. Weck makes 100% glass jars that are a good alternative. Crate and Barrel sells them here.
  • Use stainless steel containers in the freezer instead of freezer bags.
  • Use a stainless steel water bottle (like the Klean Kanteen) instead of plastic bottles.
  • Don’t drink bottled water from plastic bottles, especially when they’ve been exposed to sunlight.
  • Parents: use glass baby bottles instead of plastic. Evenflo is a commonly available brand you can buy at Target, Wal-Mart, Walgreens, Rite-Aid, etc. and online at Amazon and other retailers.

Special note for Sous Vide users: After reading this study, I’m feeling very uncomfortable about the idea of eating anything that comes out of a plastic bag that has been sitting in a hot water bath for several hours. This is a crushing blow, as I love cooking with the Sous Vide. But in light of the evidence that even BPA-free plastics bags leach chemicals with EA even without added stress like a hot water bath, I think erring on the side of caution is probably wise.

UPDATE 10-28-11: make sure to read the comments section for some good recommendations.

UPDATE 11-7-11: check out this article on Nom Nom Paleo, one of my favorite Paleo food blogs. She did some homework and found some information claiming that re-usable silicon bags don’t have EA chemicals. However, Stuart Yaniger, one of the authors of the paper I referenced in this article, commented on her post (and below) that most silicon products do, in fact, leach EA chemicals. I’m also wary of the claim that FoodSaver bags don’t have any EA without 3rd party, independent testing. As Yaniger’s article demonstrated, we should assume all plastics have EA until proven otherwise.

Resources for those who want to avoid plastic entirely

188 Comments

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  1. Excellent article! I have Hashimoto’s, and strongly suspect that exposure to plastics plays a role in autoimmune illnesses & cancers. I am making a conscious effort to use non-plastic food & water containers as much as possible.

  2. Hi Chris,

    Most butchers I know wrap meat in plastic instead of paper. What would you do if you were in my situation?

  3. “Conclusions: Many plastic products are mischaracterized as being EA free if extracted with only one solvent and not exposed to common-use stresses. However, we can identify existing compounds, or have developed, monomers, additives, or processing agents that have no detectable EA and have similar costs. Hence, our data suggest that EA-free plastic products exposed to common-use stresses and extracted by saline and ethanol solvents could be cost-effectively made on a commercial scale and thereby eliminate a potential health risk posed by most currently available plastic products that leach chemicals having EA into food products.”

    The above is the conclusion to the abstract of the cited article. Since plastic is everywhere, and generally unavoidable, perhaps the best plan would be to start publicizing this news as widely as possible, and hope for a public outcry similar to the one that helped free us of BPA in food related plastics. But frankly, the greatest amount of exposure we all have to BPA is the coating on the receipts we get at every store. You can refuse them, but half the time I forget. Plastic, like junk food, seems to be everywhere.

  4. Hi Chris,
    What about the fact that new houses are plumbed with plastic PVC piping rather than copper? are there any studies showing whether anything leaks into your tap water?

  5. What about BPA free breast milk stuff – pump, tubes, freeze bags? What could those be replaced with – to use/freeze?
    And in general – would it be safer to use breast pump to provide your baby with breast milk, or better not, due to the danger of BPA/EA contamination?
    Which would be the healthier choice?

  6. Thanks for this article. Now this has me thinking. I was considering buying a FoodSaver system and a chest freezer so I would be able to buy meat in bulk and try to save money in the long run. Now I am not so sure what the best way to store large cuts of meat would be. Will need to research further.

  7. I have a favorite plastic cup I have been using for years. Does the EA activity or BPA content eventually dissipate from the plastic item if used/washed enough?

    • You probably aren’t watching this thread anymore, but maybe my answer will help someone else.

      My husband has a Ph.D. in chemical engineering and does research on the biological applications of various chemicals. This includes the rates of dissipation of chemicals from an underlying substrate in drug delivery systems.

      When I told him about the plastics issue, the first thing he said is that the chemicals with EA will eventually stop leaching out.

      The problem is that we don’t know when, because the plastics have not been thoroughly characterized. “Characterized” is a technical term for describing all of the relevant chemical properties of a material.

      In short, the answer is “yes,” but that does not give us any useful information about how long it takes or how much stress to the material it takes for the chemicals to completely dissipate.

  8. I butcher our own game meat and I also help out with butchering on a friend’s farm. I have always used paper to wrap our meat. I was dismayed to find out, a couple of years ago, that the butcher paper is lined with either soy oil (hello GMO) or a petrochemical wax derivative. There really just isn’t a great option. Even the wax paper that is sold as unbleached and a healthier alternative is lined with soy instead of a petroleum base (not much better).

    I use glass jars with glass lids. I was luck to inherit many, but they can still be found at vintage shops. Aren’t the ones you linked to still made with plastic? Our glass storage containers all have glass lids as well. Easily found at any thrift store and so well made compared to anything on the market now. You can see my glass jar and lid setup here: http://www.tribeoffive.com/2009/10/fermenting-veggies-for-happy-tummy.html

    • I agree, there isn’t a perfect option. I think I’d prefer the risk of soy oil leaching into my food than chemicals with more significant EA, though.

        • Chris, this is not correct. Silicones can be formulated to be free of EA, but most of them are not. We’ve seen even expensive, high-purity medical grade silicones leach easily detectable amounts of estrogenic chemicals. The low molecular weight silicones (e.g,, the ones used for parchment paper) can be highly estrogenic.

          • Thanks for clarifying, Stuart. It’s great to have your input here. Admittedly, this is somewhat confusing as there is a lot of conflicting information out there. I’ve seen claims elsewhere the Jarden’s Food Saver bags don’t have any EA, but I’m hesitant to trust them after reading your paper – especially without any independent verification. Did you happen to test the Food Saver bags in your study?

            • To be honest, I didn’t know about the silicone sous vide bags until today, though it’s a clever enough idea, functionally, that my first reaction was, “Of course!” So, no, we haven’t assayed them.. Haven’t tested Jarden, either, but one other popular brand (often seen advertised on TV) showed really high levels of EA. We tend not to publish brand names, but NGOs who have contracted us will be doing so more and more.

              I’m tempted to try to make my own sous vide bags- it’s a technique I’ve always found interesting (I love cooking!) and we have a little film extruder and a vacuum heat sealer…

              • My take after all of this discussion is that it’s safest to assume that all plastic has EA unless proven otherwise, by an independent lab. Is that how you approach it at this point?

                • Exactly. Recycle number (often touted as a guide) means nothing. To make things worse, you also have to consider the independent lab- are they using current methods (e.g., BG-1 or MCF-7 in vitro assays) or older, less reliable methods (e.g., uterotrophic assays). There’s at least one product we’re aware of that advertises itself as EA-free, but they don’t disclose any details about how the testing was done other than the name of the lab. When we looked at the product, the EA was anywhere from 60% to 120% of that of human estrogen. Not encouraging, to say the least.

      • Not all parchment paper is coated with silicone. Some are coated with “Quilon” which contains chrome and may leach heavy metals, according to this site: http://www.ifyoucare.com/Baking%20products.htm
        I like the If You Care baker’s parchment, but it’s not great for wrapping because the silicone makes it very slippery! It’s not too expensive either–even at Whole Foods a roll is cheaper than a roll of bleached, toxic Reynolds baking parchment you buy at the grocery store. And you can use the IYC parchment at higher temperatures than the Reynolds brand.

        I was thinking of perhaps using squares of this paper under the lids of my canning jars. Most of the time, the lids don’t physically contact the food anyway–I don’t use them for canning, only storage.

        • Re Stewart’s reply:

          Oh, oh, so that paper isn’t OK either??? Yikes!

          I have pretty severe asthma, and when I bake (I still bake breads for others even though I don’t eat it myself anymore) I used the baker’s parchment because the flours and meals used to help slide dough from the peel to the stone burn during baking and irritate my lungs.

          Nothing is safe (maybe the universe is trying to tell me to stop poisoning others with bread???).

  9. Thanks for this. I just started replacing plastic food containers for glass, but will now speed up the process. I almost always freeze meat in the wrapping from whole paycheck, and was congratulating myself for that until I remembered that the meat has a plastic film around it. Oh, well. Butcher’s paper and then a plastic bag sounds like the way to go. It is difficult to freeze things like chicken parts in a stainless container without getting freezer burn. Blech. Does waxed paper contain plastic? It occurres to me that I don’t know how they make that.
    As for the sous vide, I was eager to buy one, but was always put off by the continual need for and cost of the bags. I seems to me that anything you can do in a sous vide you can do in a slow cooker or even a decent cast iron pan in a low and slow oven.

    • “I seems to me that anything you can do in a sous vide you can do in a slow cooker or even a decent cast iron pan in a low and slow oven.”

      Oh, I don’t think that’s true! (I’ve had my Sous Vide Supreme since they came out two-plus years ago, and I use it all the time.) I’m going with Mark Sisson’s 80%. I do use glass in the fridge for everything — but give up my Sous Vide Supreme?! Not for love or money! (Or health!) If I’m saving it (I often cook several meals at a time), I do take the meat out of the sous vide bag (after icing it for a hour), and store it in glass in the fridge. But some things I will spend the time and energy to manage, and others? {shrug} There is no perfect life, only a better one.

  10. Does the plastic wrap or lid (BPA or no) need to be touching the food or liquid it is containing in order to allow leaching of chemicals? If so this seems impossible to get away from as very few containers on the market are made with glass lids! I already store everything in the fridge and out in glass containers (generally Pyrex and Mason jars) and use plastic lids which don’t rust and aren’t touching the food/liquid inside — is that good enough?

    Also, freezing broth and raw dairy for longer storage is extremely difficult in glass. Any suggestions for that?

    • I’d assume if the lid isn’t coming into contact with food, it’s not a problem. However, I think getting the BPA-free lids I linked to in the article is a safer choice. We have them at home.

      For the freezer, you can use stainless steel or maybe wrap food in freezer paper before you put it in a bag.

      • Dear Chris,

        Thank you for some valuable piece of information. what is your opinion about Composite CANs for packing of different products??? These CANS are basically a composition of Kraft Board, at the bottom and Top we have Tin and inside we have aluminium foil as protection against moisture. Do you recommend this packaging for food packing against plastic and Tin???

  11. If meat is thoroughtly wrapped in freezer paper and then put in a zip style plastic bag do you think that would avoid any problems?

    • I’m glad this topic came up just as I’ve been making plans to go deer hunting soon-maybe I’ll be able to figure out another way to process the meat; I think I’ll try your idea, Molly.

      For saving meat long-term, I always thought I had to get my packaging as airtight as possible to prevent freezer burn.(?) This seems especially important with fish-although now that I think of it, one year I froze all my salmon by putting the piece of salmon in a ziplock, and then filling the ziplock with water. It’s certainly more labor-intesive than a vacuum-sealer, you kinda have to prop it up in the freezer until it freezes, and it does take up more space, but the fish came out tasting just fine, with no change in texture.

  12. Hey, I solved that problem a couple of years ago–I purchase the wide-mouth Mason or Kerr bottling jars, both small and large, and use them for storage in the fridge, or elsewhere! I use the silver lids, so it gives a vintage look, but there are other advantages: better storage size in fridge, you can see what’s in the jar and the amounts you are saving are great for another meal (when I fill up the quart, I dispose of the rest, because my family will only eat it, maybe, one more time!).

    Question: what about those “seal-a-meals” and the plastic they use in sealing food inside–what are they made of and are they safe?

    • The tops for Mason and Kerr jars have BPA. So either you need to make sure the food in them is not coming into contact with the food inside, or use BPA-free lids. I don’t know about “seal-a-meals”, but as the article suggests, you pretty much need to consider all plastic food storage containers as having EA.

      • There is actually BPA in the aluminum rings? Gosh, I didn’t know that! I never fill to the top, so there is no contact, but maybe I better rethink this?

        • So, when you are “canning” your fruits, etc., you are actually using lids that contaminate your food? How do you “can” or “preserve” your food then?

            • Folks might want to know that the Tattler lids are made with formaldehyde. I’d recommend Weck jars. They have glass lids.

              Also- “Tupperware” is a brand name, and I don’t think they make glass containers. (?)

          • So using my old fashioned bailer lid canning jars with the ball rubber rings, are allot safer. These jars are not reccomended by the USDA. However they were my grandmothers then my mothers then passed down to me.Been using them for 50 years now.
            Will be looking for more at antique stores.

        • It’s not in the rings. It’s on the underside of the flat lid that faces the inside of the bottle.

            • How about using the rings + a small piece of rectangular aluminum foil. A bay-area yoghurt company currently packages their yoghurt using this method.

          • You can flip the flat lid over, so the plastic side faces up. That works for Kerr jars, although I don’t can for shelf storage, so I don’t know if it will work for that use. Thanks for sharing the Weck jars.

  13. Great summary, I’ve been researching the effects of BPA and the conundrum that arrives is the idea of a “dose-response” curve, meaning different things happen at very low and very high doses, and seemingly nothing happens in the middle where industry likes to point to for safety and recommended intakes. Nature does this naturally with how our food interacts with our gene expression, but when hijacked by man-made chemicals, the effects may not be so subtle and kind – especially when you’re dealing with a pregnant mother and growing child.

    Appreciate your work!

  14. What about wrapping foods for long term storage in the freezer? I wrap up game meat in saran wrap or ziplocs to get all the air out, then freezer paper. And I’ve also eaten lots of vacuum-sealed salmon…can you recommend any good alternatives?

    • I’m still researching this myself. But I know some people use stainless steel containers in the freezer.

  15. Good to know. I sometimes do get bottled water here at my office which is supposedly in a BPA free bottle, but I did wonder if it was still safe. Looks like I’m going to be donating my old plastic tupperware as well!

      • or, re use them in different ways, to store crayons, or playdough, or things that will not be ingested. Might be a better solution?

        • Agreed. Even if your local recycling program accepts (some) plastics, much of it doesn’t actually get recycled anyway, ending up in a landfill or incinerated, further poisoning the environment.