Legally speaking, food additive refers to any substance used in the production, processing, treatment, packaging, transportation or storage of food. A substance used for a specific purpose, such as a sweetener, is referred to as a "direct additive" and is typically listed on the food's ingredient label. Indirect food additives, on the other hand, are substances that find their way into foods in small amounts due to packaging, storage or other handling.http://www.gshflag.com/food-additive/