Bioaccumulation, distribution and metabolism of BDE-153 in the freshwater fish Carassius auratus after dietary exposure

• We investigated the distribution and bioaccumulation of BDE-153 and metabolites.
• Eight debrominated and four oxidative metabolites were identified and quantified.
• Three possible metabolic pathways of BDE-153 were established in crucian carp.

Polybrominated diphenyl ethers (PBDEs) are of great environmental concern due to bioaccumulation and biomagnification in different food chains. However, significant biotransformation of some congeners via reductive debromination has been observed during in vivo and in vitro laboratory exposures. Little is known about the fate of 2,2′,4,4′,5,5′-hexabromodiphenyl ether (BDE-153) in fish. In the present study, crucian carp (Carassius auratus) were exposed to BDE-153 at a concentration of 10 μg/g in food for 28 days. BDE-153 and its metabolites in different tissues were identified and quantified using gas chromatography coupled with tandem mass spectrometry and ultra-high performance liquid chromatography coupled with tandem mass spectrometry. In addition to eight debrominated metabolites, four oxidative metabolites were detected 4′-hydroxy-2,2′,4,5′-tetra-BDE, 6-hydroxy-2,2′,4,4′-tetra-BDE, 2,4-dibromophenol and 2,4,6-tribromophenol. With regard to the concentrations of BDE-153 and the major metabolites, the contribution order of different tissues was bile>brain>liver>gill>muscle. The highest concentrations of BDE-153 and metabolite 2,2′,4,4′-tetrabromodiphenyl ether were detected in bile at 808 ng/g and 157 ng/g, respectively. Our results suggested that three possible metabolic pathways of BDE-153 occurred in crucian carp via dietary exposure: debromination, hydroxylation and cleavage of the diphenyl ether bond. These findings indicated evidence of the bioavailability of BDE-153 from food in the form of debrominated metabolites and oxidative metabolites in freshwater fish, which is critical to understanding the complete risks associated with PBDE bioaccumulation and metabolism in humans and wildlife.