The Mechanics of the Sesame Loophole: How Cross-Contact Rules Led Bakers to Intentionally Add Allergens, and How the FDA is Responding

To comply with a federal law designed to protect people with sesame allergies, America's largest commercial bakeries are intentionally adding sesame flour to the plain white bread, hamburger buns, and snacks you pack for lunch. It is a regulatory paradox that has left allergic consumers scanning grocery aisles with fewer safe options than before, prompting the U.S. Food and Drug Administration to rethink how it regulates food allergens from the ground up.[7]

The situation stems from the Food Allergy Safety, Treatment, Education, and Research (FASTER) Act, which officially designated sesame as the ninth major food allergen in the United States. When the law took effect on January 1, 2023, it required manufacturers to clearly declare sesame on product labels and, crucially, to implement stringent controls to prevent cross-contact in their facilities.[1]

For the baking industry, preventing cross-contact is a monumental physical challenge. Sesame seeds are tiny, static-prone, and notoriously difficult to scrub out of the crevices of industrial dough mixers, wire conveyor belts, and massive commercial ovens. Sesame flour dust can drift through the warm air of a bakery and settle onto adjacent production lines, making a truly sesame-free environment incredibly expensive to maintain.[3]

Faced with the choice of either building entirely separate, dedicated sesame-free facilities or risking costly recalls and liability from trace contamination, several major producers found a third option. They began intentionally adding small amounts of sesame flour or seeds to their standard recipes.[3]

By making sesame an intentional ingredient, bakeries can simply print "Contains: Sesame" on the back of the bag. This practice technically complies with the letter of the FASTER Act, as the allergen is fully disclosed to the shopper. However, it completely subverts the spirit of the law, abruptly transforming previously safe staples—like the plain buns served at major fast-food drive-thrus—into off-limits hazards for the 1.6 million Americans allergic to the seed.[3][6]

The FDA has been highly critical of the practice. In public statements, the agency acknowledged that while adding sesame and labeling it does not violate the law, it creates an outcome the FDA strongly opposes. The agency has repeatedly urged manufacturers to follow its draft guidance on minimizing cross-contact rather than taking the easy way out.[1][3]

The tension eventually escalated into direct enforcement action. In June 2024, the FDA sent a formal warning letter to Bimbo Bakeries USA—one of the largest bakery companies in the country—for intentionally adding sesame to its products and for listing sesame on labels of products that did not actually contain it, simply to cover potential cross-contact risks.[2]

In a response letter later revealed by watchdog groups, Bimbo Bakeries defended its approach. The company argued that it could not reliably control trace amounts of sesame across its manufacturing network, determining that adding it as an ingredient was the "most protective approach" to ensure allergic consumers were warned.[2][6]

The standoff highlights a fundamental flaw in the current U.S. allergen regulatory framework: it is entirely binary. Under current rules, an allergen is either intentionally present and declared, or it must be completely absent. There is no legally defined safe harbor for trace amounts of cross-contact.[5][7]

This zero-tolerance approach forces companies into a corner. If a bakery tests a batch of plain sourdough and finds a microscopic trace of sesame dust from a previous run, that entire batch is considered adulterated and subject to a costly public recall. Without a defined threshold of what constitutes a dangerous amount, companies over-label or intentionally bake the allergen right into the dough to shield themselves from liability.[4][7]

To solve this, the FDA is now exploring a systemic overhaul. In February 2026, the agency convened a major Virtual Public Meeting and Listening Session on Food Allergen Thresholds. The goal is to move away from the binary system and toward a risk-based threshold model.[1][5]

A threshold model relies on clinical data to determine the minimum amount of an allergen protein required to trigger a physical reaction. For example, international health organizations have established a reference dose of just 2 milligrams of total protein for sesame—a speck so small it is barely visible to the naked eye, but a concrete number that quality-control managers can actually test for.[4]

If the FDA adopts similar risk-based thresholds, it would give food manufacturers a practical, quantitative target. If a bakery can prove through rigorous testing that any potential sesame cross-contact falls well below the 2-milligram threshold, they would not be required to declare it as an ingredient or use a precautionary "may contain" label.[4][5]

This shift would align the United States with emerging global standards, such as those being adopted by the Codex Alimentarius Commission. More importantly, it would remove the legal incentive for companies to intentionally add allergens to safe foods, finally delivering on the FASTER Act's promise of expanding, rather than restricting, safe choices for allergic consumers.[4][7]