Debromination of Polybrominated Diphenyl Ether Congeners BDE 99 and BDE 183 in the Intestinal Tract of the Common Carp (Cyprinus carpio)

Abstract

Polybrominated diphenyl ether (PBDE) congener patterns in biota are often enriched in tetra-, penta-, and hexabrominated diphenyl ethers, which is believed to result from the use of the commercial “pentaBDE” formulation. However, our evidence suggests that debromination of PBDEs occurs within fish tissues leading to appreciable ac cumulation of less brominated congeners. This suggests that PBDE body burdens can reflect both direct uptake from exposure and debromination of more highly brominated congeners. We conducted two independent dietary exposure studies using the common carp (Cyprinus carpio) to trace the fate of 2,2‘,4,4‘,5-pentabromodiphenyl ether (BDE 99) and 2,2‘,3,4,4‘,5‘,6-heptabromodiphenyl ether (BDE 183) in fish tissues. Carp were fed food spiked with individual BDE congeners for 62 d, and depuration was monitored during the following 37 d. Significant debromination was observed, converting BDE 99 to 2,2‘,4,4‘-tetrabromodiphenyl ether (BDE 47) and BDE 183 to 2,2‘,4,4‘,5,6-hexabromodiphenyl ether (BDE 154) and another as yet unidentified hexa-BDE congener. The BDE 99 concentration rapidly declined from 400 ± 40 ng/g ww in the food to 53 ± 12 ng/g ww in the gut content material sampled 2.5 ± 1 h following feeding. At least 9.5 ± 0.8% of the BDE 99 mass in the gut was debrominated to BDE 47 and assimilated in carp tissues. In the BDE 183 exposure, approximately 17% of the BDE 183 mass was debrominated and accumulated in carp tissues in the form of two hexa-BDE congeners. In both exposure studies, the concentration of the exposure compound decreased significantly in the gut within 2.5 ± 1 h following ingestion. This rapid decrease in the concentration of the BDE congeners could not be explained entirely by debromination to quantified products or fecal egestion. Reactions occurring within the gut transform BDE congeners to other products that may accumulate or be excreted. Further studies are needed to identify and determine the effects of these BDE metabolites.

Separation of polybrominated diphenyl ethers in fish for compound-specific stable carbon isotope analysis

“…The abundance of BDE-47 compared to total PBDEs increased from 30% in the Penta-BDE mixture to 85% in fish, whereas the contribution of BDE-99 to total PBDE decreased from 47% in the Penta-BDE mixture to 0.47% in fish (Zeng et al, 2012). A previous study conducted by Stapleton et al (2004) demonstrated that common carp can transform BDE-99 to BDE-47. The δ 13 C of BDE-99 was − 28.5‰, which is lower than that of BDE-47 (− 25.7‰) by approximately 2.8‰.…”

Sorption of PBDE in low‐density polyethylene film: Implications for bioavailability of BDE‐209

“…This relative difference ranges from 0 to 70% at 60 d with an average of 30 AE 24%, falls below 20% for all but one congener (BDE-181, with a relative difference of 37%) at 240 d, and diminishes at 365 d (the relative difference for BDE-181 stands at 22%) (Table S4). Clearly, a calibration time of 60 d, a time duration often used in fish exposure experiments [5][6][7], can yield reasonable accuracy when C w is determined with the laboratory-calibrated C pe /C w . We previously obtained a curvilinear relationship between the logarithm of PDMS-water partition coefficient (log K f ) and log K OW for PCBs with the turning point at log K OW approximately equal to 7 to 7.5 [17,18], which is similar to the fieldobserved correlations between log-based bioconcentration factor and log K OW [19][20][21].…”

“…Limited data on dietary uptake of PBDEs have been acquired through laboratory studies [5][6][7][8][9]23] and are summarized in Table S4. For northern pike (Esox lucius), dietary uptake efficiency decreases singly from BDE-47 (92 AE 20%) to BDE-99 (62 AE 10%) and to BDE-153 (40 AE 10%) [23] with increasing log K OW (Table 1).…”

“…Previous studies have demonstrated that the net dietary uptake efficiency (parallel to bioavailability) of BDE-209 in common carp (Cyprinus carpio) was much lower than those for BDE-28, -47, -99, -153, and -183 [5][6][7]. Two independent studies [8,9] also reported low dietary uptake of BDE-209 in rainbow trout (Oncorhynchus mykiss).…”

Identification of highly brominated analogues of Q1 in marine mammals

“…Marine halogen exchange reactions occur primarily by light-activated radical reactions or nucleophilic exchange (Ballschmiter, 2003 has been observed in carp (Stapleton et al, 2004) and rats (Yamaguchi et al, 1988), respectively. Various microbial dehalogenation reactions are known (Janssen et al, 2001).…”