ToxStrategies’ scientists have proposed potential expansions of the use cases for the threshold of toxicological concern (TTC) in human health risk assessment applications. Analyses indicate that conservative TTC values for chemicals are, on average, approximately six-fold lower than IRIS derived reference dose (RfD) values for noncancer effects. The findings have three potential applications: (1) serve as provisional toxicity values estimated from TTC Cramer Classifications in data-poor or emergency situations, (2) serve as a comparator for toxicity criteria derived by multiple agencies or stakeholders, and (3) identify RfD values that might warrant reanalysis when they are substantially lower than their corresponding TTC value. Importantly, the findings reaffirm the health protective nature of TTC values, with the majority of TTC values being lower than their corresponding RfD values.
The open-access article was published in Regulatory Toxicology and Pharmacology.