Threshold of Toxicological Concern (TTC)

Genotoxic impurity exposure level associated with theoretical risk

The threshold of Toxicological Concern (TTC) is defined by PIC/S PI 046-1 Guideline on Setting Health Based Exposure Limits for Use in Risk Identification in the Manufacture of Different Medicincal Products in Shared Facilities as, "The TTC represents the genotoxic impurity exposure level associated with a theoretical cancer risk of 1 additional cancer in 100,000 patients when exposed over a lifetime." A TTC should be used if there is limited toxicological data available for cleaning agent or process residue. Any use of a TTC in cleaning validation must be approved by a toxicologist.