For more information, visit Ziploc's website, and go to the FAQ page. As you can see, all Ziploc® brand items are Dioxin free. Ziploc® freezer bags state on their box that they are microwavable safe. Microwave temperatures can easily exceed the heat of the water you will use for your dinner on the trail. 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.