"Food grade plastics are made from a specific list of plastics approved by the FDA (which may include dyes and recycled plastic that have not been determined to be harmful to humans). Once a plastic container has been used to store non-food items (like detergent or paint), it can no longer be considered food grade. Plastics containers that are not food grade may leach plasticizers into food on contact. Due to the nature of plastics, they have a high affinity for fats. Plastics that come in contact with an oil-based substance will almost always be irrevocably altered and the plastic may never become truly clean once again. Contact to foods that are high in fat may cause leaching of the original oil-based substance into the food even if the plastic was originally food grade......................................Microwave safe plastics are food grade plastics (which do not leach plasticizers) that are known to be able to withstand higher than normal temperatures. Plastics that are not microwave safe may leach harmful substances when heated in a microwave oven. (There was an internet e-mail scare/hoax that was passed around claiming the USDA or FDA and independent researchers showed that dioxin (a plasticizer) leached out of plastic wrap onto food being microwaved. This is untrue since all microwave safe plastics are dioxin free. Saran and Ziploc both maintain that their product lines are completely plasticizer free..........................................The S.C. Johnson Company says that the larger Ziploc brand bags are microwave safe. All Ziploc bags are made of microwave safe materials, but bags smaller than 1 quart size may be too thin to withstand the temperature of the food being microwaved. Be sure to vent Ziploc bags to allow steam to escape during microwaving. Please note that not all resealable plastic bags are microwave safe, you'll want to check with the manufacturer". ~Cookingforengineers..................................................................."Microwave plastic wraps, wax paper, cooking bags, parchment paper, and white microwave-safe paper towels should be safe to use. Do not let plastic wrap touch foods during microwaving..................................Never use thin plastic storage bags, brown paper or plastic grocery bags, newspaper..." ~United States Dept of Agriculture Food Safety Inspection Service [FSIS]........................................................"If you heat up plastics, you could increase the leaching of phthalates from the containers into water and food. Containers labeled microwave safe should have less leaching than other plastic containers..................................Microwaving food in contact with plastic wrap is another potential source of exposure, but a few years ago manufacturers in the U.S. replaced PVC plastic wrap with low-density polyethylene (LDPE), which does not contain phthalates. Plastic wrap from other countries or marketed for commercial or non-food uses may still contain PVC.....................................The Food and Drug Administration has found that only small amounts of phthalates migrate from plastic containers and plastic wrap into food. However, you can reduce the potential for exposures by using glass containers or plastics that are known to be free of phthalates, as well as plastic wrap that are known to be phthalate-free. In any case, make sure that the plastic wrap is not in contact with the food (which can melt plastic onto the food)". ~Johns Hopkins Bloomberg School of Public Health. jhsph.edu......................................."One use though for the bags that is not recommended is boiling the bags. One of the more popular emails floating around concerns the "Zip loc Omelette" where you boil eggs in a bag for 12-15 minutes, in a pan of water. It works quite well, but the boiling water can weaken the bag, or if the bag touches the hot pan, it can melt. Some confusion can occur with this, until the person asking the question realizes that to do "FBC Method" cooking you are not boiling food in the bag, but rather, adding hot water to the bag! The water cools down below boiling pretty quick as the food absorbs that heat and is cooked. Most major name brand freezer bags are made of 100% polyethylene. Most bags are 3 mil thick. As with any question, it does come down to your own personal feelings. If you do not like plastics, then look above for ways to use our recipes and methods using the one pot method. Again we as authors and site owners, do not take any legal responsibility for the use of any materials or methods described on this website, or in our books, nor of any products mentioned in them. It is a personal choice of yours". ~trailcooking.com.......................................................My personal position I don't know and don't care...........................As a rule I don't tend to buy into any of the tinternet scare stories like this. I thought the whole BPA thing was hilarious. From over protective mothers and baby bottles snowballing to grown adults throwing away their water bottles in fear, just funny. I think there may be some merit to this simply because of how stuff gets named. I still use the generic Hoover to label my vacuum cleaner although it's been a bunch of Dysons and Bissells since I owned anything Hoover. I figure Ziploc could be exactly the same way with self-sealing bags for a lot of people, and that could easily trump any pedantry about what genuine Ziplocs may give off and under what conditions..................................Ultimately though I don't care. I don't concern myself with the plastics and rubber and whatnot that's in Moroccan hash 'cos Moroccan hash is nasty even without knowing that. That it's only £300 a lump is a clue too that it isn't going to be wonderful. Similarly, I don't eat eggs cooked in an orange not because of some scare story about pesticides and oranges, just that eggs cooked that way are unappealing. Same applies to a bunch of the aluminium scare story stuff too. It occurs to me that brewing up rhubarb to put on my couscous is going to make for a crap food long before I consider the properties of which metal pan. Same here; lazy Sous-vide cooking may well be all the rage in restaurants but it strikes me as a repellent way to cook a breakfast. This egg mangling technique just preserves my revulsion. To me, getting out in the sticks is a leisure activity not some deliberate survival training. On that, eggs cooked like this can stay right back on the shelf next to poached hedgehog unless there's an emergency, no matter what the cooking vessel.
