Allergenic source material may inadvertently be present in processed foods due to crosscontact in the processing environment. A key area with potential for cross-contact is in the changeover from production of a product containing allergenic material to a product not containing that material.

Food processing operations within one site are often carried out on the same processing line using the same equipment. This creates potential for ingredients from one product or process to be unintentionally carried over into the next product. This is called cross-contact or crosscontamination and is a particular safety issue for consumers with a known food allergy. These unintentionally carried over ingredients are not required to be on the food label which poses a risk to food allergic consumers.