The acute oral median lethal dose of 2,4,6 Trinitro-3-Bromoanisole (TNBA) in rats was determined to be 2,000 mg/kg. Subacute administration of TNBA result in mortality at doses of 250 mg/kg-d and above that was preceded by weight loss, decreased food consumption, and stomach lesions. TNBA was acutely caustic to the epithelial lining of the stomach, with dose-dependent increase in prevalence and severity. Amount rats that survived to their schedule necropsy at day 14, the most striking observation was dose-dependent splenomegaly, as we as dose-dependent macrocytic anemia and neutrophilia. The lowest observed adverse effect level (LOAEL) was 62.5 mg/kg-d (only tested in females). Benchmark dose (BMD) analysis was conducted using splenomegaly in females as the critical effect. Using a benchmark response of 10 , the BMD was 59 mg/kg-d and the 95 lower confidence level (BMDL10) was 41 mg/kg-d.