Folks, feralcooks.com take its photography seriously. This week, I have elected to go without images. The science tells the story and I would not know how to illustrate it. So, cast your mind back to a time when anything worth reading came without images. Next week I will double your ration of food porn!
Most, if not all, of the people who read this blog do do because they care about food. One of the clearest movements in food recently has been the application of science to the field. Yes, the corporations who developed post-war convenience foods had food science engineers. There is nothing new under the sun. However, the focus of the science has shifted away from construction of processed foods towards the molecular level reaction of the foods we ingest. Tony, Karl and I are, by no means, egg-headed intellectuals, but we each read Kenji Lopez-Alt (seriouseats.com) and David Chang (luckypeach.com & momofuku.com). It is fascinating stuff.
I recently blogged about preparing casseroles with the specific purpose of freezing them in containers for freezing and microwaving for convenience. In truth, this was the basis for my food business and I spent a fair bit of time researching the packaging that I used in order to reduce the possibility of contaminants leaching into the food once the container was heated as part of the reheating of the packaged food in a microwave.
I did my best at the time (2003), but there was very little known about the subject at that time and very few vendors who would be willing to inform the public of the possible hazards of using their products. Today there is a little more information out there. Not only are people wanting to know what is in the storage containers, but their water bottles and, more recently, the bags that they are using to prepare food for sous-vide cooking. In fact, I was prompted to do the research for this blog when reading a sous-vide recipe which called to “put ingredients into a Ziplock bag and place in your water-bath.”
This struck me as a potentially dangerous thing to do. I buy storage bags (sometimes this brand) for holding/refrigerating food, but would be very nervous that there woud be leaching of chemicals once heated with food. As far as I am aware, Ziplock have never suggested that their bags are good for reheating and would be unlikely to acknowledge any liability if they were used in this way. I should probably contact them and find out.
So what king of chemical leaching are we talking about and in what kind of plastic does it occur?
The most common internet rumor campaign surrounds the dangers of dioxins. Dioxins are carcinogenic and not naturally occurring and are a product of incineration. The most common way for them to find their way into the body is via water as a consequence of release into the atmosphere during incineration and reintroduction into the water system via rainfall. Nothing in this description mentions plastics and that is because, according to Rolf Halden, PhD, assistant professor in the Center for Water and Health at Johns Hopkins Bloomberg School of Public Health they do not occur in the plastics from which reusable containers are manufactured.
The chemical that is found in plastics is Bisphenol A (BPA). In fact, I would hazard to guess that most of the readers here scour the labeling of plastic goods to ensure that they are buying BPA FREE plastics. According to the American Plastics Council web site, “Bisphenol A is one of the most extensively tested materials in use today. The weight of scientific evidence clearly supports the safety of BPA and provides strong reassurance that there is no basis for human health concerns from exposure to BPA.”
So, if not dioxins nor Bisphenol A, then what do we have to worry about?
While discussing food safety as part of the sous-vide techniques, ChefSteps notes:
“Here’s what we know now: According to the latest research that we’re aware of, the safest plastics are food-grade high-density polyethylene, low-density polyethylene, and polypropylene. Virtually all sous vide bags are made from these plastics. (The inner layer of nearly all sous vide bags is polyethylene.) And most name-brand food-storage bags and plastic wraps are also made from polyethylene. This is a very active area of research, and reputable plastics manufacturers have demonstrated the increasing safety of their products.
Now, other plastics that may be in your kitchen, such as inexpensive, bulk plastic wraps (still commonly made from polyvinyl chloride or polyvinylidene chloride), can contain harmful plasticizers that have been shown to leach into fatty foods such as cheese and meat. We do not recommend using these, ever. Legitimate concerns exist about food exposed to these plastics at higher temperatures—when you microwave food wrapped in plastic, for instance. We believe it’s worth it to spend a little extra on one of the trusted, known, brand-name options.
And the chemicals likely to leach when working at high temperatures? Chris Kresser, paleo enthusiast and science-based nutritionist has done extensive research on out behalf. In a web-posting entitled How plastic food containers could be making you fat, infertile and sick, gets to the heart of the matter.
“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.
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.”
It is the increase in estrogen activity that increases the risk of cancer. If transfer of BPA via water bottles may be an issue, you may well imaging that heating up the plastic and ingesting the contents needs to be taken into consideration before choosing containers. In further studies it was found that 90% of BPA FREE plastic containers still produces Estrogenic Activity (EA) and, once stressed, that figure became 100%.
Kresser goes on to suggest:
– 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;
– recent epidemiological studies strongly suggest that chemicals with EA produce measurable changes in the health of various human populations.
I am not a scientist and so I will copy and paste Kresser’s Conclusion. I have linked to his article above and will do so again after.
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.
Chris Kresser article.
There is hope!
Paloe enthusiast Michelle Tam (nomnompaleo.com) is both thoughtful and eloquent. She has done a great deal of research on this matter as a sous-vide fan who did not want to give up this useful cooking method. In her post, Cooking Sous-Vide: Plastic Safety, Tam laments the dangers of plastics, especially those that have been used for sous-vide (but, you can ratchet-up the possibilities when you introduce a microwave). Do not let her casual writing style fool you, Michelle is right on the mark.
“I did some serious digging, y’all. And luckily, I learned that there are some bags on the market that are indeed safe for sous vide purposes, and pose no problems from a BPA or EA perspective. The key is to stick with vacuum bags that are free of BPA, phthalates, and other plasticizers. It’s the plasticizers – chemical additives like phthalates that increase the pliability and fluidity of the plastic – that contain EA.
I was able to confirm, for example, that Jarden’s FoodSaver bags are made from polyethylene glycol and nylon, and don’t contain BPA, phthalates, or other plasticizers with EA-leaching additives.”
I have taken this to heart and now only use FoodSaver bags. Tam, however, is correct to call out sou-viders like me, who use the bags once before pitching them into the recycle bin. She is an advocate of reusable silicone food pouches. At $20.00 a piece they are not cheap. However, their reusability, added to the reduced likelihood of chemical leaching, might just make them one helluva bargain.
As for me, I still have many yards of FoodSaver bags before I have to make a decision. That is my story and I am sticking to it.