Health risk assessments should, where possible, be based on substance-specific toxicity data. Often, no such data are available, and appropriate read-across information cannot be identified. In such cases, default tolerable exposure values based on chemical structure can be assigned by applying a threshold of toxicological concern (TTC) approach, which can also prove useful in screening and prioritising chemicals for further assessment. This is confirmed by EFSA in its new draft guidance report, which focuses on the use of TTC in food safety assessment. This new guidance complements existing comprehensive reviews of the TTC methodology from EFSA and the World Health Organization, providing practical advice on its application. The applicability of the TTC approach is defined, as are substance inclusion/‌exclusion criteria, and the TTC decision tree is fully explained. Guidance is also provided on the application of the approach to chemical mixtures and to risk assessments for infants and children. Notably, EFSA supports the existing TTC thresholds (in µg/kg bw/day) of 30 (Cramer I substances), 9 (Cramer II substances), 1.5 (Cramer III substances), 0.3 (organophosphates and carbamates) and 0.0025 (potential non-threshold genotoxins).

European Food Safety Authority (2018). Guidance on the use of the Threshold of Toxicological Concern approach in food safety assessment.


The above items were taken from the December 2018 issue of Toxicology and Regulatory News which is sent automatically to members of bibra.

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