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assumptions about the biological response thresholds. In that case, the thresholds are actually based on using one of the other three approaches and should not be considered an analytical methods-based threshold.

Advantages. A threshold established using the analytical methods-based approach can easily be incorporated into any applicable FDA compliance programs that combine a specific standard method with a standardized sampling scheme.

Limitations. Several factors limit the applicability of the analytical methods-based approach to establish a threshold for gluten. At this time, only one commercially available analytical method has been AOAC validated, and that method was validated for detection at a relatively high concentration of gluten. In addition, there are limited data on the performance of the available methods in the wide variety of food matrices that could potentially contain gluten. Therefore, further characterization of available methods would be necessary before an analytical methods-based threshold could be established. Appropriate methods would need to be developed for the detection of oat gluten.

Finding 7. The analytical methods-based approach could be used to establish a threshold for gluten. However, if this approach is used, the threshold should be replaced by a threshold established using another approach as quickly as possible.

b. Safety Assessment-Based Approach. The safety assessment-based approach could be used to establish a threshold for gluten based on NOAELs or LOAELs reported in the literature in combination with appropriate uncertainty factors. Clinical data in the literature are limited, but a few studies are available that meet the Threshold Working Group's data quality criteria. The currently available clinical studies do not report NOAELs. However, studies are available that could be used to establish a LOAEL from which a threshold could be derived.

Advantages. Establishing a threshold based on NOAELs or LOAELs and the application of appropriate uncertainty factors to estimated exposure levels is fairly straightforward. When there are limited data in the literature, the application of appropriate uncertainty factors can provide confidence that the majority of the sensitive populations will be protected. Establishing thresholds using the safety assessment-based approach and currently available clinical data has the advantage of being directly linked to biological effects.

Limitations. The primary limitation of this approach is the dearth of available prospective clinical data and the general lack of information about the impact of chronic low-level consumption of gluten on the emergence of symptomatic disease in individuals with latent or silent celiac disease. At the current time, the size of the combined uncertainty factors needed would be substantial due to the general lack of data; applying large uncertainty factors to the available data could lead to a gluten threshold that is not achievable, as a practical matter, in foods.

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