Metabolism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in chickens

Polybrominated diphenyl ethers (PBDEs) are an important class of persistent, organic pollutant that, based on previous studies in rodents, are poorly metabolized and bioaccumulate in lipophilic stores of the body. Because humans typically consume the fat and skin of chicken, a single (14)C-radiolabeled dose (2.7 mg/kg; 5.64 mumol/kg) of the most common PBDE in the environment, that is, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), was administered to determine its metabolic disposition in male broiler chickens. Orally dosed BDE-47 was readily absorbed from the gut of chickens and was estimated to be 73% bioavailable. Cumulative tissue retention at 72 h was 60.2% of the dose. BDE-47 was deposited preferentially in lipophilic tissues, and the decreasing rank order of concentration on a wet weight basis was adipose tissue, skin, gastrointestinal tract, lung, carcass, muscle, liver, and kidney. When concentrations were adjusted for lipid content, the levels of BDE-47 in the principal edible tissues in chicken, that is, adipose tissue, skin, liver, and white and dark meat, were very similar to one another. Excretion of unbound metabolites in excreta was <1% of the dose, but bound radioactivity was a major component of excreta at >12% of the dose. Alkaline hydrolysis of bound material yielded a hydroxylated tetrabromo metabolite. The metabolic pathway of BDE-47 in chicken included mono-oxidation, mono-oxidation/debromination, and debromination. The present results suggest that trimming the fat and skin from chicken would substantially reduce human exposure to PBDEs during the consumption of chicken.