The unknown compound UBC-1 previously described as the major organobromine contamination in the blubber extract of a hooded seal (Cystophora cristata) from the Barents Sea was identified as 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE). DPTE, which is the main component of the brominated flame retardant (BFR) Bromkal 73-5 PE, was synthesized by electrophilic addition of bromine to allyl-2,4,6-tribromophenyl ether (ATE). The chirality of DPTE was proven by gas chromatographic enantioseparation of the synthesized racemate. On the basis of GC/ECNI-MS ion chromatograms (m/z79 and 81), DPTE was the dominating organobromine compound in blubber and brain samples of hooded seals and harp seals (Phoca groenlandica) from the Barents and Greenland Seas. The concentrations of DPTE in blubber and brain were up to 470 and 340 microg/kg wet weight. Next to DPTE, the natural dibromo-trichloromonoterpene (MHC-1), the anthropogenic BDE 47 and BDE 99, as well as ATE, 3,5-dibromo-2-(2',4'-dibromo)-phenoxyanisole (6-MeO-BDE 47), 2-bromoallyl-2,4,6-tribromophenyl ether (BATE), and 4,6-dibromo-2-(2',4'-dibromo)-phenoxyanisole (2'-MeO-BDE 68) were present with decreasing relevance. BATE, which was detected for the first time in environmental samples, was synthesized from DPTE by E2 elimination. In brain samples of the harp seals, DPTE, ATE, and BATE were the most abundant organobromine compounds, whereas polybrominated diphenyl ethers (PBDEs) and MHC-1 were virtually absent. This indicated that DPTE, ATE, and BATE were able to penetrate the blood-brain barrier. The general co-occurrence of ATE and BATE in samples contaminated with DPTE support the hypothesis that these compounds are biotransformation products of DPTE. Anaerobic transformation studies of DPTE with super-reduced corrinoids resulted in the formation of ATE. Furthermore, 2,4,6-tribromophenol (TBP) and two other unknown minor transformation products were detected.

No abstract

An as yet unidentified origin of elevated concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) in soil and sediment has repeatedly been described from different locations around the world, including Australia. Natural sources have been hypothesized to account for such contamination, which is characterized by a distinctive dioxin profile, in particular, elevated levels of octachlorodibenzo-p-dioxins (OCDD) as well as relatively low contributions of polychlorinated dibenzofurans (PCDFs). The present study investigated whether OCDD formation via anthropogenically derived precursors represents a possible source in such samples. Soil and sediment from Australia and Hawaii were screened for known pesticide derived dioxin precursors. Two pesticide formulations containing pentachlorophenol (PCP), which are well-known to contain predominantly OCDD impurities, were also analyzed. Polychlorinated phenoxyphenols (PCPPs), common byproducts of pesticide production, were detected at parts-per-billion (ppb) levels in two PCP formulations and in five environmental samples. Of particular interestwasthe presence of the PCPP isomer 3,4,5,6-tetrachloro-2-(2,3,4,5,6-pentachlorophenoxy)phenol (nonaC2PP), often also termed predioxin, in these samples. This compound readily undergoes ring closure to form OCDD under a range of conditions and environments. In addition, the pesticide PCP itself, which also represents a potent precursor to OCDD formation and is known to contain OCDD impurities, was detected in some environmental samples. The evidence from this study indicates that pesticides and their impurities play an important role in the dioxin contamination of Australian soils and sediments, as well as other locations with similar PCDD/F patterns. The results further suggest that formation of OCDD from pesticide derived precursors may be a possible past, present, and future pathway for contamination of environmental samples.

No abstract

No abstract

The anaerobic transformation of the technical octabromo diphenyl ether mixture, DE-79, was investigated by incubation with two super-reduced corrinoids, dicyanocobinamide and cyanocobalamin (vitamin B12). The transformation produced 33 brominated diphenyl ethers (BDEs), 23 of which could be assigned to known structures. Within 1 d, the hepta- to nona-BDEs in DE-79 were almost quantitatively transformed with dicyanocobinamide to lower-brominated homologs. Along with the decrease of high-brominated congeners, concentrations of some tetra- to hexabromo congeners initially increased, followed by a decreasing or constant concentration during longer incubations. Super-reduced cyanocobalamin also was able to transform BDE congeners of DE-79. Whereas the transformation rates of hepta- to nona-BDEs of DE-79 by both corrinoids were comparable, tri- to hexa-BDEs were susceptible to further transformation by super-reduced cyanocobalamin. Incubation of DE-79 with either corrinoid produced significant amounts of BDE 49. Because this congener is found in small quantities in both penta- and octabromo technical BDE mixtures, it may be a suitable indicator for reductive debromination of higher-brominated BDEs. Isolated BDE 196 was incubated as well with super-reduced dicyanocobalamine. After 1 d, 13 BDEs could be detected, with BDE 153, BDE 100, and BDE 99 dominating. After 7 d, only tetra-BDEs or lower-brominated BDEs were detectable. It could be shown that reductive debromination by super-reduced corrinoids is a possible source for lower-brominated BDEs (i.e., BDE 47, BDE 99, BDE 153, and BDE 154). The patterns observed with our bench-scale study design demonstrate that anaerobic transformation in the presence of reducing agents can help to explain the occurrence of environmentally relevant BDE congeners (e.g., BDE 47, BDE 99, and BDE 153).

No abstract

Two gas chromatography/mass spectrometry (GC/MS) methods for the determination of polybrominated biphenyls (PBBs) by isotope dilution analysis (IDA) using 13 C 12 -PBB 153 in the presence of polybrominated diphenyl ethers (PBDEs) were compared. Recovery of 13 C 12 -PBB 153 which was added to the extracted lipids before sample purification was commenced ranged from 88-117% (mean value 98.2 W 8.9%). Nevertheless, IDA analysis of PBBs using 13 C 12 -labelled congeners is limited by the potential co-elution of PBBs with polybrominated diphenyl ethers (PBDEs). The pair PBB 153 and BDE 154 was inspected since M R and [M-2Br] R ions of 13 C 12 -PBB 153 and BDE 154 were only separated by 4 u. Gas chromatography/electron ionization high-resolution mass spectrometry with selected ion monitoring (GC/EI-HRMS-SIM) was suitable when m/z 475.7449 and m/z 477.7429 were used for 13 C 12 -PBB 153 because they are below the monoisotopic peak of the [M-2Br] R fragment ion of hexaBDEs at m/z 479.7. Gas chromatography/electron capture negative ion tandem mass spectrometry selected reaction monitoring (GC/ECNI-MS/MS-SRM) measurements could be applied because 13 C 12 -PBB 153 and BDE 154 were separated by GC on a 25-m Factor Four CP-Sil 8MS column. Comparative measurements with GC/EI-HRMS-SIM and GC/ECNI-MSMS-SRM were carried out with samples of Tasmanian devils from Tasmania (Australia), an endangered species due to a virus epidemy which has already proved fatal for half of the population. Both techniques verified concentrations of PBB 153 in the range 0.3-11 ng/g lipids with excellent agreement of the levels in all but two samples. The PBB residue pattern demonstrated that PBB pollution originated from the previous discharge with technical hexabromobiphenyl which is dominated by PBB 153. Other congeners such as PBB 132 and PBB 138 were detected in the Tasmanian devils but the proportions relative to PBB 153 were lower than in the technical product. Samples of healthy and affected Tasmanian devils showed no significant difference in the PBB pollution level. The PBB concentrations in the Tasmanian devils were significantly below those causing toxic effects. On the other hand, PBB concentrations were one level or even higher than PBDEs.