Submitted to: Xenobiotica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2020
Publication Date: 12/8/2020
Citation: Hakk, H., Pfaff, C.M., Lupton, S.J., Singh, A. 2020. Absorption, distribution, metabolism, and excretion of three [14C]PBDE congeners in laying hens and transfer to eggs. Xenobiotica. 51:335-344. https://doi.org/10.1080/00498254.2020.1860269.
Interpretive Summary: Polybrominated diphenyl ethers (PBDEs) were used as flame retardants in consumer products for decades. PBDE levels in environmental samples have generally been declining in recent years, however certain PBDEs remain at elevated levels. Food animal exposure to PBDEs is a concern because meat, milk, or eggs could serve as exposure sources to consumers. Experiments were conducted to determine the absorption, distribution, metabolism, and excretion of three major PBDEs in laying hens and to determine if PBDEs are transferred to eggs. PBDE absorption generally depended on the number of bromines on the specific PBDE; compounds having a high number of bromines were relatively poorly absorbed and PBDEs with moderate numbers of bromines were highly absorbed. Elimination of PBDEs in eggs was significant with yolks containing higher levels than egg white. Fatty tissues including meat and skin of chickens also contained relatively higher PBDE levels than other tissues. The study demonstrates that chickens readily absorb some major PBDE compounds and that poultry products could be a potential PBDE exposure source for consumers.
Technical Abstract: Polybrominated diphenyl ethers (PBDEs) levels in environmental matrices have generally declined following their phaseout as flame retardants. The objective of this study was to determine the absorption, distribution, metabolism, and excretion of three persistent PBDEs in laying hens and their transfer into eggs. Laying hens (n=4 per congener) received a single oral dose of BDE-99, -153, or -209 and eggs and excreta were collected daily for 7 days, then tissues were collected and analyzed. Cumulative BDE-209 excretion was 93% of dose, and bioavailability was approximately 17%. Lesser amounts of BDE-99 (41%) and -153 (26%) were excreted with bioavailabilities of 87% and 79%, respectively. Phenolic metabolites were observed in excreta extracts from BDE-99 dosed birds. Cumulative transfer of BDE-209 to eggs was 2.6%, while transfer to eggs was 15% and 27% for BDE-99 and -153, respectively. Egg residues were primarily present in yolk (12.3%, 23.5%, and 2.1% of the total dose for BDE-99, 153, and 209, respectively). Adipose, intestine, and thigh muscle contained the highest levels of radioactive tissue residues. These studies demonstrate movement of PBDE residues into edible tissues and eggs of laying hens.