Probabilistic quantitative risk assessment of unintended egg, milk and wheat allergen exposure under Japan's threshold-based food labelling system.

Japan's Food Labelling Act forbids precautionary allergen labelling and mandates declaration of specified allergens above 10 μg/g. To evaluate whether this threshold sufficiently protects food-allergic consumers, we analysed 979 egg, 696 milk and 380 wheat oral food challenges. Eliciting doses (ED01/ED05) were estimated using Bayesian benchmark-dose modelling with model averaging across five parametric distributions. Model-averaged ED05 values were 12.94 mg for egg, 2.05 mg for milk, and 6.71 mg for wheat. Previously published Bayesian exposure assessments of hidden egg, milk, and wheat proteins in processed foods were combined with portion-size distributions and dose-response curves to estimate reaction risks under high- and low-intake scenarios via Monte-Carlo. Under the high-intake scenario, estimated risks were 3.7×10-5 for egg, 2.0×10-3 for milk, and 2.6×10-3 for wheat; under the low-intake scenario, risks were 1.8×10-6, 2.6×10-4, and 5.5×10-4, respectively. By integrating Bayesian benchmark-dose modelling with exposure assessment, this study provides the first comprehensive evaluation of Japan's allergen labelling thresholds. Our results indicate that unintended exposure to egg, milk, and wheat in Japanese processed foods is minimal and that the 10 μg/g labelling threshold affords a sufficient safety margin relative to ED05 in Japanese individuals, although food-specific mitigation may be needed, particularly for wheat.