On December 2, 2014 almost 100 participants got together at a stakeholder meeting on the Threshold of Toxicological Concern (TTC) approach. This event was followed by an expert meeting on December 3-5, 2014 that aimed to review the science underlying the TTC concept. Both events were jointly organized by the European Food Safety Authority (EFSA) and the World Health Organization (WHO) and took place in Brussels, Belgium. According to Angelika Tritscher from the WHO, the overall goal was to develop a globally harmonized decision tree. The outcome of the TTC stakeholder meeting was to be considered during the TTC expert meeting.

At the stakeholder meeting, two presentations specifically covered the optimization of the decision tree: Jie Shen from the Research Institute of Fragrance Materials (RIFM), U.S. compared the results of expert judgments using the Cramer decision tree with two software-aided evaluations (Toxtree and the OECD QSAR-toolbox). Based on these comparisons he identified weaknesses in the decision tree that could be optimized in the future. Thierry Cachet, who was speaking on behalf of the International Organization of the Flavor Industry (IOFI), also presented a project aiming at the revision of the Cramer decision tree. Stephanie Melching-Kollmuss of BASF introduced a project currently conducted by ILSI Europe on the reevaluation of the TTC cancer potency dataset. During further presentations and discussions it was pointed out that the threshold values, as they were determined by Munro and colleagues in 1996, can still be judged conservative on the basis of new data. However, the quality and the underlying assumptions of the Munro database were challenged by Hans Muilerman from the Pesticide Action Network (PAN) Europe. In the final discussion it was clearly stated by representatives of the U.S. Food and Drug Administration (FDA) and EFSA that the TTC is not adopted for risk assessment of food contact materials under both legislations. However, it is stated in a scientific opinion on the TTC published by EFSA in 2012 that “the TTC approach could be useful for substances with low-level migration from food contact materials”.

Read more:

EFSA (December 2, 2014). “Threshold of Toxicological Concern – EFSA meets stakeholders