TDCPP is a chlorinated analog of tris(2,3-dibromopropyl)phosphate (Tris) which is one of the most detected organophosphorus flame retardants (OPFRs) in the environment. In Vitro: Exposure to TDCPP does not significantly affect cell viability until at concentration >68 μg/mL. HCECs show a 16% cell viability loss after exposing to 136 μg/mL TDCPP. Moreover, TDCPP induces a sharp decrease in viable cells (87%) after exposing to ≥272 μg/mL TDCPP. Based on cell viability, the LC₅₀ value for TDCPP is 202 μg/mL using a nonlinear regression. Compare to controls, TDCPP-exposed cells exhibit a concentration-dependent increase in apoptosis. Anti-apoptotic Bcl-2 protein expression is increased to 1.4 fold after exposing to 2 μg/mL TDCPP, 1.2-folds at 20 μg/mL but dynamically decreased to 0.4 fold at 200 μg/mL compare to control. The caspase-3 activity is increased to 2.1 folds of the control at 200 μg/mL TDCPP^[1]. TDCPP inhibits cell growth at lower concentrations (IC₅₀ of 27 μM), while cell viability and toxicity are affected at higher concentrations (IC₅₀ of 171 μM and 168 μM, respectively)^[2].