Levels of Hexabromocyclododecane in harbor porpoises and common dolphins from Western European seas, with evidence for stereoisomer-specific biotransformation by cytochrome P450.

B. N. Zegers, A. Mets, R. Van Brommel, C. Minkenberg, T. Hamers, J. H. Kamstra, Graham John Pierce, J. P. Boon

Research output: Contribution to journalArticle

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Abstract

Commercial hexabromocyclododecane (HBCD) is a high-production-volume flame-retardant applied in polystyrene foams. It contains three stereoisomers, of which gamma-HBCD always dominates. Here we report on the levels of HBCD in blubber of harbor porpoise and common dolphin from different European seas. The highest total (1)HBCD levels were measured in harbor porpoises stranded on the Irish and Scottish coasts of the Irish Sea (median concentration 2.9 mu g (g of lipid)(-1)) and the northwest coast of Scotland (median concentration 5.1 mu g (g of lipid)(-1)). The median levels in other areas were, for the harbor porpoise south coast of Ireland, 1.2 mu g (g of lipid)(-1), for the coasts of The Netherlands, Belgium, and France north of Calais (southern North Sea), 1.1 mu g (g of lipid)(-1), for the east coast of Scotland (northern North Sea), 0.77 mu g (g of lipid)(-1), and, for Galicia (Spain), 0.1 mu g (g of lipid)(-1). The median levels for the common dolphin were, for west coast of Ireland, 0.9 mu g (g of lipid)(-1), for the French coast of the English Channel between Normandy and Brest, 0.4 mu g (g of lipid)(-1), and, for Galicia, 0.2 mu g (g of lipid)(-1). A subset of 10 harbor porpoise and 9 common dolphin blubber samples representing all areas were analyzed by LC/MS to determine the diastereomeric composition of their HBCD residues. All samples showed exclusively the peak of alpha-HBCD. To test if biotransformation by the cytochrome P450 system could explain the observed compositional difference with technical HBCD mixtures, a number of in vitro assays with microsomal preparations of liver were carried out. We had to revert to material stored at -80 degrees C from laboratory rats and a fresh harbor seal found dead in the Dutch Wadden Sea, since such liver samples of cetaceans were not in our possession. The in vitro assays showed that beta- and gamma-HBCDs were indeed significantly metabolized when incubated in the presence of NADPH as electron donor, compared to a set of reference samples which were identical except for the addition of NADPH. In contrast, the peak of alpha-HBCD did not decrease significantly in the presence of NADPH. In separate microsomal assays with beta- and gamma-HBCDs, new peaks of brominated compounds (signal at m/z = 79 or 81) with masses of [M + O] were formed only when NADPH was added. This confirms the process of cytochrome P450 mediated biotransformation. Although rat and harbor seal belong to different families of the mammalia than the cetaceans, we propose that biotransformation by the cytochrome P450 system is also the most likely process to explain the exclusive accumulation of alpha-HBCD in harbor porpoise and common dolphin.

Original languageEnglish
Pages (from-to)2095-2100
Number of pages5
JournalEnvironmental Science & Technology
Volume39
DOIs
Publication statusPublished - 2005

Keywords

  • BROMINATED FLAME RETARDANTS
  • POLYBROMINATED DIPHENYL ETHERS
  • IN-VITRO
  • FOOD-WEB
  • SEDIMENT
  • ATLANTIC
  • BLOOD
  • RAT

Cite this

Levels of Hexabromocyclododecane in harbor porpoises and common dolphins from Western European seas, with evidence for stereoisomer-specific biotransformation by cytochrome P450. / Zegers, B. N.; Mets, A.; Van Brommel, R.; Minkenberg, C.; Hamers, T.; Kamstra, J. H.; Pierce, Graham John; Boon, J. P.

In: Environmental Science & Technology, Vol. 39, 2005, p. 2095-2100.

Research output: Contribution to journalArticle

Zegers, B. N. ; Mets, A. ; Van Brommel, R. ; Minkenberg, C. ; Hamers, T. ; Kamstra, J. H. ; Pierce, Graham John ; Boon, J. P. / Levels of Hexabromocyclododecane in harbor porpoises and common dolphins from Western European seas, with evidence for stereoisomer-specific biotransformation by cytochrome P450. In: Environmental Science & Technology. 2005 ; Vol. 39. pp. 2095-2100.
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abstract = "Commercial hexabromocyclododecane (HBCD) is a high-production-volume flame-retardant applied in polystyrene foams. It contains three stereoisomers, of which gamma-HBCD always dominates. Here we report on the levels of HBCD in blubber of harbor porpoise and common dolphin from different European seas. The highest total (1)HBCD levels were measured in harbor porpoises stranded on the Irish and Scottish coasts of the Irish Sea (median concentration 2.9 mu g (g of lipid)(-1)) and the northwest coast of Scotland (median concentration 5.1 mu g (g of lipid)(-1)). The median levels in other areas were, for the harbor porpoise south coast of Ireland, 1.2 mu g (g of lipid)(-1), for the coasts of The Netherlands, Belgium, and France north of Calais (southern North Sea), 1.1 mu g (g of lipid)(-1), for the east coast of Scotland (northern North Sea), 0.77 mu g (g of lipid)(-1), and, for Galicia (Spain), 0.1 mu g (g of lipid)(-1). The median levels for the common dolphin were, for west coast of Ireland, 0.9 mu g (g of lipid)(-1), for the French coast of the English Channel between Normandy and Brest, 0.4 mu g (g of lipid)(-1), and, for Galicia, 0.2 mu g (g of lipid)(-1). A subset of 10 harbor porpoise and 9 common dolphin blubber samples representing all areas were analyzed by LC/MS to determine the diastereomeric composition of their HBCD residues. All samples showed exclusively the peak of alpha-HBCD. To test if biotransformation by the cytochrome P450 system could explain the observed compositional difference with technical HBCD mixtures, a number of in vitro assays with microsomal preparations of liver were carried out. We had to revert to material stored at -80 degrees C from laboratory rats and a fresh harbor seal found dead in the Dutch Wadden Sea, since such liver samples of cetaceans were not in our possession. The in vitro assays showed that beta- and gamma-HBCDs were indeed significantly metabolized when incubated in the presence of NADPH as electron donor, compared to a set of reference samples which were identical except for the addition of NADPH. In contrast, the peak of alpha-HBCD did not decrease significantly in the presence of NADPH. In separate microsomal assays with beta- and gamma-HBCDs, new peaks of brominated compounds (signal at m/z = 79 or 81) with masses of [M + O] were formed only when NADPH was added. This confirms the process of cytochrome P450 mediated biotransformation. Although rat and harbor seal belong to different families of the mammalia than the cetaceans, we propose that biotransformation by the cytochrome P450 system is also the most likely process to explain the exclusive accumulation of alpha-HBCD in harbor porpoise and common dolphin.",
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T1 - Levels of Hexabromocyclododecane in harbor porpoises and common dolphins from Western European seas, with evidence for stereoisomer-specific biotransformation by cytochrome P450.

AU - Zegers, B. N.

AU - Mets, A.

AU - Van Brommel, R.

AU - Minkenberg, C.

AU - Hamers, T.

AU - Kamstra, J. H.

AU - Pierce, Graham John

AU - Boon, J. P.

PY - 2005

Y1 - 2005

N2 - Commercial hexabromocyclododecane (HBCD) is a high-production-volume flame-retardant applied in polystyrene foams. It contains three stereoisomers, of which gamma-HBCD always dominates. Here we report on the levels of HBCD in blubber of harbor porpoise and common dolphin from different European seas. The highest total (1)HBCD levels were measured in harbor porpoises stranded on the Irish and Scottish coasts of the Irish Sea (median concentration 2.9 mu g (g of lipid)(-1)) and the northwest coast of Scotland (median concentration 5.1 mu g (g of lipid)(-1)). The median levels in other areas were, for the harbor porpoise south coast of Ireland, 1.2 mu g (g of lipid)(-1), for the coasts of The Netherlands, Belgium, and France north of Calais (southern North Sea), 1.1 mu g (g of lipid)(-1), for the east coast of Scotland (northern North Sea), 0.77 mu g (g of lipid)(-1), and, for Galicia (Spain), 0.1 mu g (g of lipid)(-1). The median levels for the common dolphin were, for west coast of Ireland, 0.9 mu g (g of lipid)(-1), for the French coast of the English Channel between Normandy and Brest, 0.4 mu g (g of lipid)(-1), and, for Galicia, 0.2 mu g (g of lipid)(-1). A subset of 10 harbor porpoise and 9 common dolphin blubber samples representing all areas were analyzed by LC/MS to determine the diastereomeric composition of their HBCD residues. All samples showed exclusively the peak of alpha-HBCD. To test if biotransformation by the cytochrome P450 system could explain the observed compositional difference with technical HBCD mixtures, a number of in vitro assays with microsomal preparations of liver were carried out. We had to revert to material stored at -80 degrees C from laboratory rats and a fresh harbor seal found dead in the Dutch Wadden Sea, since such liver samples of cetaceans were not in our possession. The in vitro assays showed that beta- and gamma-HBCDs were indeed significantly metabolized when incubated in the presence of NADPH as electron donor, compared to a set of reference samples which were identical except for the addition of NADPH. In contrast, the peak of alpha-HBCD did not decrease significantly in the presence of NADPH. In separate microsomal assays with beta- and gamma-HBCDs, new peaks of brominated compounds (signal at m/z = 79 or 81) with masses of [M + O] were formed only when NADPH was added. This confirms the process of cytochrome P450 mediated biotransformation. Although rat and harbor seal belong to different families of the mammalia than the cetaceans, we propose that biotransformation by the cytochrome P450 system is also the most likely process to explain the exclusive accumulation of alpha-HBCD in harbor porpoise and common dolphin.

AB - Commercial hexabromocyclododecane (HBCD) is a high-production-volume flame-retardant applied in polystyrene foams. It contains three stereoisomers, of which gamma-HBCD always dominates. Here we report on the levels of HBCD in blubber of harbor porpoise and common dolphin from different European seas. The highest total (1)HBCD levels were measured in harbor porpoises stranded on the Irish and Scottish coasts of the Irish Sea (median concentration 2.9 mu g (g of lipid)(-1)) and the northwest coast of Scotland (median concentration 5.1 mu g (g of lipid)(-1)). The median levels in other areas were, for the harbor porpoise south coast of Ireland, 1.2 mu g (g of lipid)(-1), for the coasts of The Netherlands, Belgium, and France north of Calais (southern North Sea), 1.1 mu g (g of lipid)(-1), for the east coast of Scotland (northern North Sea), 0.77 mu g (g of lipid)(-1), and, for Galicia (Spain), 0.1 mu g (g of lipid)(-1). The median levels for the common dolphin were, for west coast of Ireland, 0.9 mu g (g of lipid)(-1), for the French coast of the English Channel between Normandy and Brest, 0.4 mu g (g of lipid)(-1), and, for Galicia, 0.2 mu g (g of lipid)(-1). A subset of 10 harbor porpoise and 9 common dolphin blubber samples representing all areas were analyzed by LC/MS to determine the diastereomeric composition of their HBCD residues. All samples showed exclusively the peak of alpha-HBCD. To test if biotransformation by the cytochrome P450 system could explain the observed compositional difference with technical HBCD mixtures, a number of in vitro assays with microsomal preparations of liver were carried out. We had to revert to material stored at -80 degrees C from laboratory rats and a fresh harbor seal found dead in the Dutch Wadden Sea, since such liver samples of cetaceans were not in our possession. The in vitro assays showed that beta- and gamma-HBCDs were indeed significantly metabolized when incubated in the presence of NADPH as electron donor, compared to a set of reference samples which were identical except for the addition of NADPH. In contrast, the peak of alpha-HBCD did not decrease significantly in the presence of NADPH. In separate microsomal assays with beta- and gamma-HBCDs, new peaks of brominated compounds (signal at m/z = 79 or 81) with masses of [M + O] were formed only when NADPH was added. This confirms the process of cytochrome P450 mediated biotransformation. Although rat and harbor seal belong to different families of the mammalia than the cetaceans, we propose that biotransformation by the cytochrome P450 system is also the most likely process to explain the exclusive accumulation of alpha-HBCD in harbor porpoise and common dolphin.

KW - BROMINATED FLAME RETARDANTS

KW - POLYBROMINATED DIPHENYL ETHERS

KW - IN-VITRO

KW - FOOD-WEB

KW - SEDIMENT

KW - ATLANTIC

KW - BLOOD

KW - RAT

U2 - 10.1021/es049209t

DO - 10.1021/es049209t

M3 - Article

VL - 39

SP - 2095

EP - 2100

JO - Environmental Science & Technology

JF - Environmental Science & Technology

SN - 0013-936X

ER -