Hi Gale, you are not supposed to eat food grade plastic containers. I got the following from internet search:
Imagine if you bought a cup of yoghurt, ate its contents and then ate the cup. That's the new innovation frontier in the trend towards healthier alternatives that are good for the environment. An organic food company in California is researching this product. Another example is edible films. Researchers at the University of Arkansas, Division of Agriculture have invented and patented several protein based films that can serve as carriers for certain organic acids which inhibit the growth of the three major foodborne bacteria: Listeria moncytogense, Salmonella, and E. coli. In addition, the film can be a vehicle for antioxidants, nutraceuticals, flavors, colors and other functional ingredients. Anticipated applications include fruits and vegetables, meats, seafood, frozen snacks and pizza, cereals, nuts and more. The category may be at the cutting edge of innovative trends today.
What Is Food Grade Plastic? The U.S. Food & Drug Administration (FDA) requires that plastics used in food packaging be of greater purity than plastics used for non-food packaging. This is commonly referred to as food grade plastic. Plastics used to package pharmaceuticals are held to an even higher standard than food grade.
Food grade plastic does not contain dyes or recycled plastic deemed harmful to humans. However, this does not mean that food grade plastic cannot contain recycled plastic. The FDA has detailed regulations concerning recycled plastics in food packaging.
Another aspect of food grade plastic is matching the appropriate type of plastic to the food in question. Foods that are highly acidic or that contain alcohol or fats can leach plastic additives from the packaging or container into the food. As a result, you should only use plastic containers that are FDA approved for the particular type of food the plastic will come into contact with.
Finally, it should be noted that a plastic container can no longer be considered food grade if it has been used to store non-food items like chemicals, paint, or detergent.
Types Of Plastic
In the United States, the following codes represent the seven categories of plastic used in nearly all plastic containers and product packaging:
<1>PET or PETE (polyethylene terephthalate) is a clear, tough polymer with exceptional gas and moisture barrier properties. PET's ability to contain carbon dioxide (carbonation) makes it ideal for use in soft drink bottles. Examples: Soft drink bottles, detergent bottles
<2>HDPE (high density polyethylene) is used in milk, juice and water containers in order to take advantage of its excellent protective barrier properties. Its chemical resistance properties also make it well suited for items such as containers for household chemicals and detergents. Most five gallon food buckets are made from HDPE. Examples: Milk bottles, shopping bags
<3>Vinyl (polyvinyl chloride, or PVC) provides excellent clarity, puncture resistance and cling. As a film, vinyl can breathe just the right amount, making it ideal for packaging fresh meats that require oxygen to ensure a bright red surface while maintaining an acceptable shelf life. Examples: Plastic food wrap, shrink wrap, garden hoses, shoe soles
<4>LDPE (low density polyethylene) offers clarity and flexibility. It is used to make bottles that require flexibility. To take advantage of its strength and toughness in film form, it is used to produce grocery bags and garbage bags, shrink and stretch film, and coating for milk cartons. Examples: Squeeze bottles, dry cleaning bags
<5>PP (polypropylene) has high tensile strength, making it ideal for use in caps and lids that have to hold tightly on to threaded openings. Because of its high melting point, polypropylene can be hot-filled with products designed to cool in bottles, including ketchup and syrup. It is also used for products that need to be incubated, such as yogurt. Many Cambo, Tupperware and Rubbermaid food storage containers are made from PP. Examples: Bottle caps, take-out food containers, drinking straws
<6>PS (polystyrene), in its crystalline form, is a colorless plastic that can be clear and hard. It can also be foamed to provide exceptional insulation properties. Foamed or expanded polystyrene (EPS) is used for products such as meat trays, egg cartons and coffee cups. It is also used for packaging and protecting appliances, electronics and other sensitive products. Examples: Plastic foam, packing peanuts, coat hangers
<7> Other denotes plastics made from other types of resin or from several resins mixed together. These usually cannot be recycled.
Another important type of plastic is polycarbonate, a clear shatter-resistant material used in restaurant food storage containers and recently in the Rubbermaid Stain Shield line of home food storage containers.
Hope above helps!