Threshold of toxicological concern approach for the risk assessment of substances used for the manufacture of plastic food contact materials

The objective of this work was to investigate whether the Threshold of Toxicological Concern (TTC) approach could be applied to the evaluation of substances used to manufacture plastic food contact materials (FCM). For this purpose, a new dataset of 232 substances used in FCM, fully evaluated on the basis of oral animal studies, was compared with the original Munro dataset. The extended dataset supports the differentiation between Cramer classes I and III, as the substances with the lowest no-observed-effect-levels are in class III both for the Munro et al. and the FCM datasets. The applicability of the TTC approach was also verified substance by substance, by comparing their TTC value with their tolerable intakes calculated from their no-observed-effect-level. The TTC approach, as proposed by Munro et al. in 1996, appears to be more conservative (more protective for consumers) than the complete individual risk assessment for 96% of the 845 compounds included in the investigation. For most of the substances, functional groups known to represent causes of non-applicability of the TTC approach have been identified. These figures suggest that the TTC approach can be a useful tool for prioritization of evaluations of lists of substances for which no toxicity data are available.