Use only those containers and products that have been approved for microwave use. These items are designed to withstand the high temperatures possible when cooking foods that have a high fat or sugar content. Avoid the use of cold storage containers. Margarine tubs, whipped topping bowls and cottage cheese cartons, for example, have not been approved for microwaving. High heat could cause chemicals to transfer into the food.
Waxed paper is safe.
Other paper goods such as towels, plates and napkins have not been tested for use in cooking. If using these items, for optimal safety use only plain white paper goods. Never use brown grocery bags and newspapers. These contain recycled materials and metals which could start a fire. Avoid letting plastic wrap touch foods during microwaving.