Disposition of decabromobiphenyl ether in rats dosed intravenously or by feeding

Abstract

The disposition of ¹⁴C‐labeled decabromobiphenyl ether (DBBE) in male Fischer rats dosed by feeding (0.025–5.0% of the diet) or intravenously (1 mg/kg) was determined. For rats dosed by feeding, intestinal absorption of DBBE was evident in that the intact compound was present in extracts of liver. For these rats, the size of the liver increased with increasing concentration of DBBE in the diet. Liver contained a maximum of 0.449% of the administered radioactivity at 24 h after feeding rats a diet containing 0.0277% [¹⁴C]DBBE; no other organ or tissue contained more than 0.26%. The total amount of radioactivity found in tissues was less than 7% of the dose. Of the radioactivity recovered in the feeding experiments, more than 99% was in the feces and gut contents at 72 h; a maximum of 0.012% of the dose was in the urine. In the feces of rats fed [¹⁴C]DBBE, there were three metabolites, which together comprised 1.5–27.9% of the radioactivity. Since absorption was minimal, most of the metabolism of [¹⁴C]DBBE apparently took place in the gastrointestinal tract. The metabolites increased in percent of total radioactivity with the content of DBBE in the diet, an indication that enzyme induction in intestinal bacteria may have occurred at the higher doses. More extensive metabolism of [¹⁴C]DBBE occurred after intravenous administration; only 37% of the radioactivity in the feces was unchanged DBBE. At 72 h after dosing, fecal excretion accounted for 70% of the dose; only 0.129% appeared in the urine. Muscle retained 12.9% and skin 7.25% of the radioactivity administered. In 4 h, rats with biliary cannulas excreted in the bile 7.17% of the intravenously administered radioactivity; less than 7% was excreted as intact DBBE. Biliary excretion was apparently the major route for elimination of the intravenously administered compound. The rapid excretion and extensive metabolism of DBBE, relative to other polyhalogenated compounds, are advantageous properties that may allow it to be used in place of structurally similar compounds presently employed in industrial applications.