Anything that comes in contact with food needs to be safe. Food grade plastic bags are designed to meet these standards. This includes plastic bags from those that are used in the grocery store to bags used in storage.
Just imagine the bread bag or vegetable packages, for example found in stores. These bags are often a clear plastic so customers can see the product. There are also words and logos printed on the packaging. A way to help ensure customer safety is to package these items and other food items in safe bags that have been designed for food. Such bags are available and are produced in many different colors as well as a variety of sizes to accommodate the smallest and largest foods.
Usually to be food grade, a plastic bag needs to meet FDA and USDA requirements. It needs to be deemed safe to come in contact with food and this must be safe on a continual basis. You will notice some food grade bags are heavy duty and are used in shipping. Items can go from the grower to the bag to the table and remain as safe as possible.
These bags are durable and designed to be used for dry as well as wet foods. The styles vary as well to help fit the food properly in the bag. Often these plastic bags are made of specialized polyethylene.
The consumer also uses food grade bags when picking their own fruits and vegetables. An example is the produce area of a grocery store has these bags available to place items for purchase. These storage bags are also purchased to help store food at home and to help prepare items for the lunch box.