Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/6/2010
Publication Date: 8/11/2010
Citation: Hakk, H., Huwe, J.K., Murphy, K., Rutherford, D. 2010. Metabolism of 2,2',4,4' Tetrabromodiphenyl (BDE 47) in Chickens. Journal of Agricultural and Food Chemistry. 58:8757-8762. DOI:10.1021/jf1012924. Interpretive Summary: Polybrominated diphenyl ethers (PBDEs) belong to the larger class of polybrominated flame retardants, which are required in many consumer products for fire safety. PBDEs are not incorporated into the consumer product, rather are added loosely. As a result, PBDEs can diffuse into the environment, which is troublesome since they are persistent, bioaccumulate in fatty tissue, and are neurotoxic. The most important PBDE in environmental samples is 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). This study was initiated to determine the metabolic behavior of BDE-47 in broiler chickens, since humans typically consume the fat and (fatty) skin of chicken. A single, oral dose of BDE-47 was administered to four male broilers, and it was found that 73% of the BDE-47 dose was absorbed from the gut. BDE-47 was deposited preferentially in lipophilic tissues, and when normalizing for lipid content the principle edible tissues in chicken, i.e. adipose tissue, skin, liver, and white and dark meat, were very similar to each another. Metabolites in the excreta amounted to less than 1% of the administered dose, although bound material in excreta suggested a greater degree of metabolism might have occurred. The metabolic pathway of BDE-47 in chickens was similar to what had previously been observed in rats and mice, and some metabolites may have the potential to interfere with thyroid hormone transport in blood. The present results suggest that trimming the fat and skin from chicken would substantially reduce human exposure to PBDEs during the consumption of chicken.
Technical Abstract: Polybrominated diphenyl ethers (PBDEs) are a relatively new class of persistent, organic pollutant that, based on previous studies in rodents, are poorly metabolized and bioaccumulate in lipophilic stores of the body. Since humans typically consume the fat and skin of chicken, we administered a single, [14C]radiolabeled dose (2.7 mg/kg; 5.64 µmole/kg) of the most common PBDE in the environment, i.e. 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 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, GI tract, lung, carcass, muscle, liver, and kidney. When concentrations were adjusted for lipid content, the level of BDE-47 in the principle edible tissues in chicken, i.e. adipose tissue, skin, liver, and white and dark meat, were very similar to each another. Excretion of unbound metabolites in excreta was less than 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.