Metabolism, excretion and distribution of the flame retardant tetrabromobisphenol-A in conventional and bile-duct cannulated rats

Abstract

1. ¹⁴C-TBBP-A (2,2-bis(4-hydroxy-3,5-dibromophenyl)propane) was administered orally to the conventional and bile-duct cannulated male Sprague-Dawley rat (2.0 mg/kg body weight). Urine, bile and faeces were collected daily for 72 h, and selected tissues were removed for distribution studies. 2. Faeces was the major route of elimination of TBBP-A in the conventional rat (9.7% of dose), and urine was a minor elimination route (0.3%). Enterohepatic circulation was suggested by biliary excretion of 71.3% and faecal excretion of 26.7% of the administered radioactivity in the bile-duct cannulated rat. 3. ¹⁴C-labelled residues in tissues were 2% in the conventional rat, and <1% in the bile-duct cannulated rat. The large and small intestines contained the majority of the tissue ¹⁴C activity for both groups of rat. Levels of TBBP-A in liver were < 0.1%, and in fat were below the level of quantification. 4. Three metabolites were characterized in 0-24 h bile samples. Glucuronic acid and sulphate ester conjugates were characterized by mass spectrometry. More than 95% of the extractable faecal ¹⁴C was identified as parent TBBP-A. 5. Negligible amounts of TBBP-A-derived ¹⁴C were associated with carrier proteins he urine and bile.