One of the food and petrochemical (including pesticides, pharmaceuticals and personal care) industries’ major efforts to protect their money-earning molecules from health & safety regulation, since 1967 has been the Threshold of Toxicologic Concern, the TTC. The TTC wears an aura of complex science, but its purpose is simply to eliminate the critical live mammal, chronic exposure toxicity test that is the heart of a risk assessment (RA) of chemicals.
A TTC achieves this desirable elimination by claiming to be a “threshold” (“safe”) dose, below which it is claimed there will be no significant toxicity. A TTC is the 5th percentile (close to the most potent) chronic toxicity test result among hundreds of tested chemicals. A regulator using a TTC says that exposure below this dose will not cause a risk, despite that its toxicity is never tested (as in all RA, it is first divided by a factor meant to account for susceptibility differences—usually 100-fold).