TTC Concept within EU REACH Dutch Document

Veenstra and Kroese (2005) have discussed the concept of TTC for use within REACH. 

It is mentioned that the TTC concept has been incorporated in the risk assessment processes in a number of regulatory schemes as a scientifically sound tool to justify waiving or generation of animal data. It is also stressed that, in contrast to approaches such as read-across or chemical categorization, the use of the TTC is not focused or limited to the identification of potential hazards but also provides a quantitative estimate of potency. 

It is furthermore noted that the TTC concepts, including the structure-based approaches, are derived from databases covering substances used as direct and indirect food additives, pesticides, and industrial chemicals, and cover toxic effects related to systemic exposure to these chemicals. In addition, it is underlined that TTC has not been developed for endpoints associated with direct contact such as irritation or sensitization. 

It is concluded that the TTC concept for systemic toxicity is suitable as a starting point for a tiered testing and risk assessment strategy within REACH. However, it is also underlined that the 

TTC concepts require a minimum set of information in order to be applied successfully. A draft generic TTC concept under REACH is proposed and it is stressed that the information requirements for the draft generic TTC concept under REACH are consistent with the tiered approach proposed by Kroes et al. (2004) (Section 4.13.3). 

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