Ok, what about cooking in plastic? Won’t it give me cancer?
There’s so much written about the chemicals in plastic bags and the dangers they can pose to public health. I’m deeply grateful to all of the folks who have come before me in this research, making it easier for me to consolidate the wealth of information available.
The major concern is around phthalates, and BPA which causes estrogenic activity (EA), and may be linked to certain cancers.
“Chemicals having estrogenic activity (EA) reportedly cause many adverse health effects, especially at low (picomolar to nanomolar) doses in fetal and juvenile mammals.” http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222987/
Most bags, including Ziploc and FoodSaver bags, contain layers of polyethylene which contain no BPA or phthalates. Polyethylene is inert and there has been no toxicity found with this plastic compound. The AMES test (which checks for damage to DNA) proves negative, and polyethylene has no estrogen-like compounds in it.
As Richard Nikoley quotes in a comment:
The temperatures of sous vide are also low (polyethylene doesn’t begin softening until 195F), although I would imagine that a very small amount of polyethylene would still make it onto the surface of your food through diffusion. Polyethylene, however, is considered biologically inert, and scientists have been unable to detect any toxicity in animal tests (unlike BPA). It passes the Ames test and other studies of damage to DNA, and doesn’t have a similarity to estrogen.
As always it’s up to you, but the taste and health benefits (less AGE production, nutrient loss, and protein degradation, and more retention of fatty acids) that sous vide provides far outweighs what seems to me to be an almost arbitrary possibility that it will harm me.”
In a 2012 article, Dr. Terry Simpson addresses the plastics used in sous vide cooking and states: “most plastic wraps, zip-lock bags, freezer bags, and Sous Vide bags are free of phthalates, and BPA. The change from polyvinylidene chloride to polyethylene was for safety, but it did make the “cling” wrap cling less. Polyethelene is stable at low temperature Sous Vide cooking.”
“Almost all commercially available plastic products we sampled—independent of the type of resin, product, or retail source—leached chemicals having reliably detectable EA, including those advertised as BPA free. In some cases, BPA-free products released chemicals having more EA than did BPA-containing products.”
How much of a health hazard is actually posed by the small amounts of estrogen that might leach from certain plastic additives? We all know that it’s virtually impossible in modern society to avoid having ANY plastic or silicone from touching our food — from meat and vegetables that come sealed in plastic wrap, to dishes we stir with silicone spatulas, to meals prepped in restaurants. We also know that our chances of being hurt by something cooked at low heat in a food-grade silicone bag are likely much lower than our chances of getting hurt (or killed) any time we choose to drive or ride in a moving vehicle — so what lengths should reasonable people take to avoid all plastics and silicone products?
For me, I’m going to do my best to avoid needlessly throwing food in plastic containers, thanks to the information you provided. But given what I’ve learned, I think I’m still going to be sous viding using the products above, just as I’m not giving up on bicycles, cars and trains! 🙂
Things to remember:
There are chemicals and toxins everywhere in our daily life, and we all take steps to limit our exposure to them.
You will always be cooking at a temperature well below the point at which the polyethylene in either Ziploc or FoodSaver bags begins to soften (195F). Even so, polyethylene is considered biologically inert and are not known to leach any chemicals that are suspected of causing cancer or disrupting hormones.
If you’re concerned about the dangers of plastic despite this, or feel it’s not appropriate for your household, there are alternatives. Many foods can be prepared in vacuum sealed glass jars (be sure to get lids that are BPA free), and silicone bags (though some studies also pose concerns about the safety of even food-grade silicone). And never take risks with someone with a compromised immune system.
Finally, io9 has a great write up to quickly answer all of your burning plastic questions (ok, don’t burn your plastics, obviously):
I hope that helps, and that you find the best way for you and your family to enjoy the wonders of sous vide cooking!