Threshold of Toxicological Concern (TTC)

Literature review and applicability

image of Threshold of Toxicological Concern (TTC)

In the regulation of food contact articles and flavouring substances, the TTC concept (Threshold of Toxicological Concern) has been developed as a substitute for substance-specific information. The TTC concept is based on the analysis of the toxicological and/or structural data of a broad range of different chemicals, with the aim to set an exposure-value below which no toxicity testing is necessary. Recently, application of the TTC concept has been proposed as a tool in risk assessment of industrial chemicals within REACH, both for defining when no testing is needed based on exposure information and as a substitute for effect values. The proposal concerns both human health and the environment. The present report does not advocate the use of TTC instead of substance specific toxicity data for risk assessment of industrial chemicals within REACH at time being. This conclusion is based on current knowledge and understanding of the concept, and on limitations and uncertainties in the derivation of TTCs. Furthermore, the suitability of the TTC concept so far has not been evaluated for the diverse group of industrial chemicals. In addition, the possible consequences for the level of protection of human health and the environment resulting from applying the TTC concept in the risk assessment should be examined.




The establishment of TTC is based on the analysis of the toxicological and/or structural data of a broad range of different chemicals. The TTCs might be used as substitute for substance specific information in situations where there are limited or no information on toxicity of the compound and where the human exposure is so low that undertaking toxicity studies is considered not warranted, due to animal welfare considerations and of the costs incurred in manpower and laboratory resources.


This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error