Establishing the Allergen Threshold

Unfortunately, science does not allow us to know with certainty that a particular allergenic protein will not cause a single reaction in the entire population of sensitive individuals at a given level of exposure.

By David Joy, Contributing Editor

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The Food and Drug Administration (FDA) and the food industry recently have been grappling with the issue of allergen thresholds, de minimis levels at which an allergen can be present in food without triggering a reaction in a sensitive individual. This is an important issue connected with implementation of the Food Allergen Labeling and Consumer Protection Act (FALCPA).

A draft report recently prepared by FDA's Threshold Working Group provides some insight into FDA's thinking in this area. It also reveals a gap between the legal and regulatory need for well-defined allergen thresholds and the state of scientific knowledge in this area.

By way of review, FALCPA identifies eight major food allergens: milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat and soybeans. If a food contains one of these things or contains an ingredient or additive that contains protein derived from one of them, the food must be labeled with the name of the allergen. This labeling requirement extends to processing aids and other substances that might otherwise not be included in the ingredient declaration.

Highly refined oils derived from any of the eight major allergens are not treated as allergenic ingredients under FALCPA. Two mechanisms (petition or notification) are available to establish that other food ingredients or additives derived from the eight major allergens do not need to be treated as allergens under the law.

The question of allergen thresholds is important in several different areas under FALCPA. First, a petition seeking to establish an exemption for a particular ingredient must demonstrate that the ingredient "does not cause an allergic response that poses a risk to human health." One way of establishing this would be to identify the protein or proteins responsible for allergic reactions and show they are not present above a threshold level of concern with respect to serious allergic reactions.

Likewise, a notification seeking an exemption for a particular ingredient may include scientific evidence demonstrating that the food ingredient "does not contain allergenic protein." Unless there exists a high degree of certainty that the manufacturing process destroys all proteins present, this showing might include some idea about the threshold level of concern along with analytical data showing the protein(s) cannot be detected at this level.

Thresholds also are important in the context of developing future guidance on good manufacturing practices (GMPs) aimed at preventing cross-contamination and in the context of gluten-free claims. FALCPA directs FDA to establish criteria for the use of the term "gluten-free" on food labels.

Unfortunately, science does not allow us to know with certainty that a particular allergenic protein will not cause a single reaction in the entire population of sensitive individuals at a given level of exposure. It would not be practical or ethical to test all sensitive individuals to determine a threshold. What we can reasonably aim for is the extrapolation of thresholds that are reasonably expected to exclude serious reactions in the vast majority of sensitive individuals. And this will certainly represent a higher level of protection for these individuals than has existed prior to FALCPA.

FDA's draft report reviews four approaches that might be used to establish thresholds:
  1. Analytical methods-based, whereby the threshold would be determined by the sensitivity of the analytical method used to verify compliance;

  2. Safety assessment-based, whereby a safety factor is applied to the No Observed Adverse Effect Level (NOAEL) derived from existing human challenge studies;

  3. Risk assessment-based, whereby the level of risk associated with a particular exposure is determined, as is often done with carcinogenic risk; and

  4. Statutorily-derived, whereby a threshold is set by regulation or statute.
The report states tentatively that the quantitative risk assessment-based approach provides the strongest scientific basis for establishing thresholds. But the application of quantitative risk assessment to food allergens is relatively new, and not enough experience or data exist to use this approach exclusively.

Interestingly, thresholds based on analytical sensitivity are not favored. Thresholds established in this manner may not protect all sensitive individuals, but analytical test methods are an essential part of the equation. We have no choice but to accept their limitations for compliance verification and for determining whether a food ingredient should qualify for an exemption based on the absence of allergenic proteins.

With the Jan. 1, 2006, deadline for compliance with FALCPA rapidly approaching, many would prefer to have a better understanding of these issues. This is a case where science will be catching up with the law, and the science will evolve as the law is implemented.



David Joy is a partner at the Washington DC law firm of Keller and Heckman LLP. He specializes in food and drug law with emphasis on the domestic and international regulation of food, food additives, food labeling, antimicrobial pesticides, and medical devices. He is a member of the District of Columbia Bar and holds a bachelor's degree in chemistry. For more information about Keller and Heckman, visit the firm's web site at www.khlaw.com.

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