While individuals can be allergic to almost any protein, the FDA identifies a specific group of foods that account for the majority of severe allergic reactions in the United States. These are known as the "Big 9."Shrimp, which falls under the category ofCrustacean Shellfish, is one of these major allergens. The other eight are milk, eggs, fish (such as bass, flounder, or cod), tree nuts (such as walnuts or pecans), peanuts, wheat, soy, and the most recently added, sesame.

Identifying major allergens is a critical responsibility for a Food Protection Manager. When a guest reports an allergy to one of these items, the staff must take extraordinary care to preventcross-contact. This includes using separate, sanitized equipment and ensuring that no trace of the allergen (like shrimp juice or shells) touches the guest's meal. Mushrooms, celery, and apples (Options B, C, and D) are not currently classified as "major" allergens under U.S. law, though they can still cause reactions in sensitive individuals. Managers must ensure that all staff—from servers to line cooks—can identify the Big 9 and understand the establishment's procedures for handling allergen-sensitive orders. This includes checking labels on all processed foods, as allergens can often be "hidden" in ingredients like flavorings or thickeners.