Chemical analysis of estragole in fennel based teas and associated safety assessment using the Margin of Exposure (MOE) approach

This study describes the analysis of estragole in dry fennel preparations and in infusions prepared from them and an associated safety assessment. A wide range of estragole levels of 0.15-13.3mg/g dry fennel preparation was found. The estragole content in infusions was considerably lower ranging between 0.4 and 133.4μg/25mL infusion prepared from 1g dry material. Infusions prepared from whole fennel fruits contained about 3-fold less estragole compared to infusions prepared from fine cut fennel material. Safety assessment was performed using the Margin of Exposure (MOE) approach comparing available tumour data to the estimated daily estragole intakes from the consumption of 1-3 cups fennel tea. MOEs obtained for adults generally point at a low priority for risk management, especially when one cup of fennel tea is used daily during lifetime. MOEs for use of fennel teas by children were generally <10,000 indicating a priority for risk management. However, limiting such uses to 1-2weeks, MOEs might be 3 orders of a magnitude higher and there would be no priority for risk management. These results indicate a low priority for risk management actions for use of fennel teas especially for short-term uses proposed for the symptomatic treatment of digestive disorders.