Contribution of Synthetic and Naturally Occurring Organobromine Compounds to Bromine Mass in Marine Organisms

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Contribution of Synthetic and Naturally Occurring Organobromine Compounds to Bromine Mass in Marine Organisms
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  Contribution of Synthetic andNaturally Occurring OrganobromineCompounds to Bromine Mass inMarine Organisms  Y I W A N ,  † P A U L D . J O N E S ,  ‡ S T E V E W I S E M A N ,  † H O N G C H A N G ,  † D A V E C H O R N E Y ,  § K U R U N T H A C H A L A M K A N N A N ,  | K U N Z H A N G ,  ⊥ J I A N - Y I N G H U ,J O N G S E O N G K H I M ,  # S H I N S U K E T A N A B E ,  ∇ M I C H A E L H . W . L A M ,  O  A N DJ O H N P . G I E S Y *  , † , O , [ , ¶ , + Toxicology Centre, University of Saskatchewan, Saskatoon,Saskatchewan S7N 5B3, Canada, School of Environment and Sustainability and Toxicology Centre, University of  Saskatchewan, Saskatoon, Saskatchewan, S7N 5C8B3, Canada,Radiochemistry & SLOWPOKE Reactor, SRC Analytical Laboratories, Saskatoon, Saskatchewan, Canada, Wadsworth Center, New York State Department of Health and Department of Environmental Health Sciences, School of Public Health,State University of New York, Empire State Plaza, Albany,New York 12201-0509, Laboratory for Earth Surface Processes,College of Urban and Environmental Sciences, Peking University,Beijing 100871, China, Division of Environmental Science and Ecological Engineering, Korea University, Seoul 136-713, Korea,Center for Marine Environmental Studies, Ehime University,Matsuyama, Japan, Department of Biomedical Veterinary Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada, Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong, SAR China,School of Biological Sciences, University of Hong Kong, Hong Kong, SAR, PR China, and Department of Zoology and Center  for Integrative Toxicology, Michigan State University,East Lansing, Michigan  Received March 22, 2010. Revised manuscript received  June 17, 2010. Accepted July 8, 2010. An extraction, separation, and purification method wasdeveloped for the identification and quantification of totalbromine (TBr), extractable organobromine (EOBr), and fiveclasses of identified EOBrs. Instrumental neutron activationanalysis (INAA) was utilized to quantify EOBr and TBr. Themethodwasthenappliedtoliversamplesoftuna,albatross,andpolar bear collected from remote marine locations. Polybro-minated biphenyls (PBBs), polybrominated diphenyl ethers(PBDEs), bromophenols (BRPs), hydroxylated (OH-) andmethoxylated (MeO-) PBDEs were analyzed as identifiedEOBr. The majority of the bromine in these marine organismswas nonextractable or inorganic, with EOBr accounting for10 - 28%oftheTBr.OftheidentifiedEOBr,intunaandalbatross,naturally occurring compounds, including MeO-PBDEs, OH-PBDEs, and BPRs, were prevalent. However, the identifiableEOBrinpolarbearsconsistedprimarilyofsyntheticcompounds,including PBDEs and PBBs. Overall, 0.08 - 0.11% and0.008 - 0.012% of EOBr and TBr, respectively, were identified.The proportion of EOBr that was identified in marine organismswas relatively small compared to the proportions fororganofluorine and organochlorine compounds. This could berelated to the great diversity of naturally occurring organo-bromine compounds in the environment. Naturally occurringbrominated fatty acids were estimated to be the predominantcompounds in the EOBr fraction. Introduction Due to their persistence, bioaccumulation, and toxicity,organohalogencompoundsareofconcernascontaminantsin aquatic and terrestrial ecosystems. Some well-knownsyntheticorganohalogenssuchasperfluorooctanesulfonate(PFOS), polychlorinated biphenyls (PCBs), and polybromi-nated diphenyl ethers (PBDEs) have become ubiquitousenvironmental pollutants ( 1 - 3  ). In addition to the knownsyntheticorganohalogensthereareanumberofunidentifiedorganohalogensintheenvironment( 4,5  ).Identificationandquantification of these novel organohalogen compounds isessential for the assessment of potential risks to exposedorganisms.Synoptic quantification of individual organohalogencompoundsalongwithquantificationoftotalhalogensisaneffective method to estimate the mass balance of identifiedand unidentified organohalogen compounds in the environ-ment. Several studies have examined the contributions of known organohalogens to extractable organohalogens andtotalorganohalogensinabioticandbiologicalmatrices( 4  - 8  ).Mass balance studies of chlorine in samples collected neara former chloralkali facility indicated that the identifiedorganochlorines accounted for 48% and 1 - 35% of theextractable organic chlorine (EOCl) in sediment and biota,respectively ( 4  ). Methods for the mass balance analysis of fluorinehavebeendevelopedandappliedtoenvironmentalsamples ( 5, 8  ). In these studies, most of the fluorine ( > 50%) was in the nonextractable fraction and the identified per-fluorinated compounds (PFCs) contributed 30 - 85% of extractable organic fluorine (EOF) in human blood and wildlife tissues ( 5, 8  ).Brominated flame retardants (BFRs) have recently emerged as contaminants of concern. Among BFRs, PBDEsandpolybrominatedbiphenyls(PBBs)areofprimaryinterestdue to their high production volume, widespread use, andubiquitous occurrence in the environment ( 9, 10  ). Theoccurrenceofhydroxylated(OH-)andmethoxylated(MeO-)PBDEshasbeeninvestigatedinaquaticecosystems( 11 ),andconcentrations of MeO-PBDEs were greater than those of  * Corresponding author address: Department of Veterinary Biomed-icalSciences,UniversityofSaskatchewan,Saskatoon,SaskatchewanS7N5B3, Canada; tel (direct): 306-966-2096; tel (secretary): 306-966-4680; fax:306-966-4796; mobile: 517-614-6123; e-mail: jgiesy@aol.com. † Toxicology Centre, University of Saskatchewan. ‡ SchoolofEnvironmentandSustainabilityandToxicologyCentre,University of Saskatchewan. § Radiochemistry & SLOWPOKE Reactor, SRC AnalyticalLaboratories. |  Wadsworth Center, New York State Department of Health andDepartment of Environmental Health Sciences. ⊥ Laboratory for Earth Surface Processes, College of Urban andEnvironmental Sciences, Peking University. # Division of Environmental Science and Ecological Engineering,Korea University. ∇ Center for Marine Environmental Studies, Ehime University. O Department of Biomedical Veterinary Sciences University of Saskatchewan. [ Department of Biology and Chemistry, City University of Hong Kong. ¶ School of Biological Sciences, University of Hong Kong. + Department of Zoology and Center for Integrative Toxicology,Michigan State University. Environ. Sci. Technol.  2010,  44,  6068–6073 6068  9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 44, NO. 16, 2010 10.1021/es100914r  ©  2010 American Chemical Society Published on Web 07/22/2010  PBDEs in some samples ( 12  ). Bromophenols (BRPs), whichare structurally similar to PBDEs, are key natural flavorcomponents of some marine fish. However, synthetic BRPshavealsobeenproducedandwidelyusedasflameretardants(2,4,6-triBRP)withaworldwideproductionof9500tin2001( 13  ).Extractableorganicbromine(EOBr)hasbeeninvestigatedinavarietyofenvironmentalsamples( 4,6,14  - 16  ).However,few studies have determined the proportion of EOBr thatcould be identified, and the contribution of natural andsynthetic compounds to EOBr concentrations in environ-mental samples is unknown. In this study, the relativecontribution of natural and synthetic organobrominatedcompoundstoEOBrandtotalbromine(TBr)wasdetermined.BothEOBrandTBrweredeterminedbyinstrumentalneutronactivationanalysis(INAA)ofeithercrudesamplesororganicsolvent extracts of samples. PBBs, PBDEs, and relatedbrominated compounds were analyzed as identified EOBr( 9, 11, 17, 18  ). An extraction and cleanup method for TBr,EOBr,andfiveclassesofidentifiedEOBrwasdeveloped.Themethod was applied to determine concentrations of EOBrandTBraswellastheconcentrationsofindividualcongenersofPBBs,PBDEs,OH-PBDEs,MeO-PBDEs,andBRPsinliversof tuna ( Katsuwonus pelamis  ), five species of albatrosses( Thalassarche chlororhynchos  ,  Phoebetria palpebrata  ,  Thalas-sarche chrysostoma  ,  Thalassarche cauta  , and  Thalassarche melanophrys  ) and polar bear ( Ursus maritimus  ) collectedfrom remote marine locations. Absolute and relative con-tributions of identified EOBr to EOBr and TBr were deter-mined, and the predominant forms of brominated com-pounds in the marine organisms are suggested. Materials and Methods Tissue Collection.  Livers from fifteen albatross, ten tuna,and ten polar bear were used for quantification of TBr, totalEOBr, and identified EOBr. Albatross were collected fromthe Indian and South Atlantic Oceans, polar bear werecollectedfromNorthernandWesternAlaska,andtunawerecollectedfromtheNorthPacificOceanin1992 - 2002(Table1) ( 11 ). All samples were stored at - 20  ° C from the time of collection until analysis. Sample Preparation.  An efficient fractionation method,requiring a single extraction of 5 g ww of liver tissue thatallows for the simultaneous analysis of TBr, EOBr, and fivegroups of identified EOBr was developed (Figure 1). TheidentifiedEOBrincluded10PBBs,21PBDEs,12MeO-PBDEs,10 OH-PBDEs, and 16 BRPs. Details of chemicals andstandards are provided in Supporting Information. Toestimate the concentrations of organobromines in theenvironment,EOBrhasbeenquantifiedinvariousmatrixes,such as sediment, atmosphere, and aquatic biota ( 4, 6, 15  ).The current study is the first to compare TBr, EOBr, andidentified EOBr in tissues (Figure 1) ( 4  ). Due to the limitedsample mass available for the analysis of multiple targetcompounds,directquantificationsofTBrintissueswerenotattempted. In contrast to the method used to quantify totalchlorine (TCl) and total fluorine (TF), TBr was quantified by summingEOBrandnonextractablebromine(NEBr),andtheconcentrations of NEBr were determined by analyzing theresidues from solvent extracted samples and normalized tolipid and water contents. The calculation is based on anassumption that negligible amounts of bromine (Br) werelost during extraction.Samples (approximately 5 g wet weight (ww)) werehomogenizedandfreeze-dried.Watercontentwasmeasuredgravimetrically. Sample extraction was conducted using anaccelerated solvent extractor (Dionex ASE-200, Sunnyvale,CA). Two kinds of solvents were used for the extraction: (1) n  -hexane/dichloromethane (DCM) (1:1) at 100  ° C and 1500psi, and (2)  n  -hexane/methyl  tert  -butyl ether (MTBE) (1:1)at 60  ° C and 1000 psi. Two extraction cycles (10 min each) were performed for each solvent per sample (about 50 mLfor each solvent), and both extraction fractions were com-bined. The residual materials after solvent extraction wereair-dried and used for quantification of NEBr. The solventextract was reduced to 10 mL by rotary evaporation and 2mL was used for the determination of EOBr.Lipid content of each extract was determined gravimetri-callybyevaporatingtheremainingextracttoconstantweight.Extractswerethenspikedwithamixtureof  13 C-labeledPBB,PBDE,andBRPsurrogatesforanalysisofPBBs,PBDEs,MeO-PBDEs, OH-PBDEs, and BRPs. Thus, the spiking solutionsdid not influence quantification of Br EOBr, and the detailsoftheanalysisofPBDEs,MeO-PBDEs,OH-PBDEs,andBRPshavebeenreportedpreviously( 11 ).Themethodwasmodifiedto accommodate simultaneous identification and quantifi-cationofPBBs(Figure1).Theneutralandphenolicfractionsin extracts were separated with 0.5 M potassium hydroxide(KOH)in50%ethanol.ThemethodsforpurificationofPBDEs, TABLE 1 .  Concentrations of Bromine in Five Groups of Identified Organic Brominated Compounds, Identified EOBr, EOBr, and TBrExtracted from Liver Samples Collected from Species Inhabiting Remote Marine Locations  a speciesname water (%) lipid (%) MeO-PBDEs OH-PBDEs BRPs PBDEs PBBsidentifiedEOBr EOBr TBr tuna 67 ( 3.7 5.0 ( 2.7 0.31 ( 0.10 0.014 ( 0.005 0.45 ( 0.21 0.13 ( 0.05 0.003 ( 0.006 0.9 ( 0.3 1100 ( 540 10700 ( 3400(58 - 72) (1.9 - 9.0) (0.17 - 0.47) (0.008 - 0.03) (0.14 - 0.67) (0.063 - 0.22) (N.D. - 0.014) (0.5 - 1.3) (600 - 2000) (8300 - 17200)albatross 60 ( 2.2 10 ( 3.5 0.65 ( 0.85 0.34 ( 0.24 0.021 ( 0.033 0.19 ( 0.21 0.049 ( 0.057 1.3 ( 1.1 1700 ( 950 11300 ( 2600(55 - 64) (4.3 - 15) (0.08 - 2.8) (0.11 - 0.90) (N.D. - 0.10) (0.05 - 0.85) (N.D. - 0.21) (0.2 - 3.8) (810 - 3500) (7000 - 14400)polar bear 60 ( 5.2 7.1 ( 2.2 0.014 ( 0.01 0.004 ( 0.005 0.11 ( 0.12 0.49 ( 0.16 0.34 ( 0.29 1.0 ( 0.5 2800 ( 2300 12400 ( 6100(54 - 71) (4.7 - 12) (0.003 - 0.03) (0.001 - 0.02) (N.D. - 0.39) (0.19 - 0.68) (0.064 - 1.0) (0.5 - 1.9) (310 - 6100) (6200 - 21800) a  ng/g ww, mean  (  SD (range in parentheses). N.D. Not detected. FIGURE 1. Flow diagram for the procedure used to fractionate total bromine, extractable organic bromine, and known ex- tractable organic bromines in liver tissue samples. VOL. 44, NO. 16, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY   9  6069  MeO-PBDE, BRPs, and OH-PBDEs have been reportedpreviously( 11 ).ForanalysisofPBBs,theextractwastreated with sulfuric acid because PBBs, unlike MeO-PBDEs andPBDEs, are not degraded by concentrated sulfuric acid.Extracts were passed through a column packed with 2 g of sodium sulfate and 8 g of acidified silica (50 g of silica gelmixed with 27 mL of concentrated sulfuric acid). Afterapplication of the sample, the column was eluted with 15mL of   n  -hexane and 10 mL of DCM. Eluates were concen-tratedto40  µ LforquantificationofPBBs.Instrumentanalysesof identified EOBr are in Supporting Information. Calculations of Bromine Concentrations.  Concentra-tions of EOBr (ng Br/g ww) were determined (eq 1) where C  Brinextract istheconcentrationofbromineintheextract(  µ g/mL), 10 is the final volume of extract (mL), and  W    wet  isthe wet weight of sample (g). The residual materials aftersolvent extraction were used for quantification of Br todetermine the nonextractable Br content (NEBr). Concen-trations of NEBr (ng Br/g ww) were calculated (eq 2) where C  Br in RSP istheconcentrationofbromineintheresidualsamplepowders(RSP)(  µ g/g),Wat%isthewatercontentofthesamples(%),andLipid%isthelipidcontentofthesamples(%).Thus,theconcentrationofTBr,expressedasngBr/gww,wasthe sum of concentrations of EOBr and NEBr (eq 3).Identifiable EOBr, including PBBs, PBDEs, MeO-PBDEs,OH-PBDEs, and BRPs, were quantified in liver samples.MassesofBrcontributingtototalEOBrweredeterminedby multiplyingtheconcentrationofeachcompoundidentifiedbyitsmolefractionofBr.ConcentrationsofidentifiedEOBr were the sum Br concentrations of all detected compounds(eq 4). where  C  i   is the concentration of organic brominated com-pound  i   (ng/g ww),  N  i   is the number of Br atoms containedinthecompound i  ,MW  i isthemolecularweightofcompound i  , 80 is the molecular weight of Br, and  m   is the number of detected organobromine compounds. Bromine Analysis.  Concentrations of Br were deter-minedbyINAA.Sampleswereactivatedfor15minin1.5mLNAA-gradepolyvialsataneutronfluxof5.0 × 10 11 (n/cm 2 )/sintheSLOWPOKE2nuclearreactor(SaskatchewanResearchCouncilAnalyticalLaboratories,Saskatoon,SK,Canada).Afteractivation,  γ -rays from  80 Br were measured by   γ -ray spec-trometry by use of an Ortec model GMX20P4 HPGe solid-state detector and Ortec DSPEC Pro 8192 channel digitalgamma ray spectrometer for peak area calculations. Quan-tification was based on  γ -peaks from  80 Br ( t  1/2  )  17.6 min, E  γ  )  616 keV). The count time was 15 min. Knownconcentrations of bromoform (CHBr 3 ) dissolved in toluene were used as standards for the quantification of EOBr andTBr using INAA. Quality Assurance and Quality Control (QA/QC).  Count-ing efficiency of INAA was determined for EOBr and TBr foreach type of sample geometry. This was done by analyzing asetoffourstandardsandcalculatingcountspersecondpermicrogramofbromine(cps/  µ g).Theaverageefficiencyfactor was used to calculate the EOBr and TBr concentrations. Tosmooth out minor fluctuations that occur in individualstandards or batches, each time a new set of calibrationstandardswasquantified,anewaveragewascalculatedfromall standards run and maintained as a running average.The QA/QC for the analysis of PBDEs, MeO-PBDEs, OH-PBDEs, and BRPs has been reported previously ( 11 ). A laboratory blank and a matrix spike were analyzed for every batch of 15 samples. Beef liver was used for matrix spikesamples, and the spiking solutions were added beforeacceleratedsolventextraction.Recoveriesofspikedmaterialsfromsampleswere80 - 127%,81 - 126%,87 - 128%,81 - 123%,and 65 - 126% for PBBs, MeO-PBDEs, PBDEs, OH-PBDEs,and BRPs, respectively, in the entire analytical procedure.Concentrations quantified in spiked samples were within20% of the spiked concentrations. Thus, both accuracy andprecision of the analysis were deemed to be acceptable.Quantification of PBBs, PBDEs, and BRPs was performed with  13 C-PBBs,  13 C-PBDEs, and  13 C-BRPs as surrogates.Concentrations of OH-PBDEs were quantified relative to2,3,4,6- 13 C-TeBRPs,andMeO-PBDEswerequantifiedrelativeto  13 C-PBDEs with the same number of Br atoms.The instrumental limits of quantification for Br analysis were 2  µ g Br/g dw for solid samples and 0.08 - 0.5  µ g Br/mLfor liquid samples. Method detection limits (MDL) weredefined to be mean plus three times the standard deviationof concentrations in the blank. MDLs for compounds that werenotdetectedintheblankweresettobetheinstrumentalminimumdetectableamounts.TheMDLswere0.4pg/gww forMeO-PBDEs,0.2 - 10.1pg/gwwforPBDEs,2 - 4pg/gww for OH-PBDEs, 2.0 - 10 pg/g ww for BRPs, and 2 - 50 pg/g  ww for PBBs. For those results that were less than the MDL,a sensitivity analysis was conducted and no statistically significant differences could be found by using differentvalues ranging from 0 to the MDL. Thus, a value of 0 wasassigned to avoid missing values in statistical analyses. Results and Discussion Bromine Fractions.  Concentrations of TBr, EOBr, andidentifiedEOBrinliveroftuna,albatross,andpolarbeararepresented(Table1).Mean( ( SD)concentrationsofTBrwere10 700 ( 3400, 11 200 ( 2600, and 12 400 ( 6100 ng/g ww in tuna, albatross, and polar bear, respectively. Concentra-tionsofEOBrwereapproximately3-to9-foldlessthanthoseof NEBr, which ranged from 1100  (  540 (tuna) to 2800  ( 2300ng/gww(polarbear).Amongthespeciesanalyzed,polarbearlivercontainedthegreatestconcentrationsofbothTBrandEOBr.However,concentrationsofidentifiedEOBrwererelatively small, ranging from 0.9  (  0.3 (tuna) to 1.3  (  1.1ng/gww(albatross)andaccountedforonlyasmallproportionof the TBr.Few studies have investigated concentrations of EOBr inmarine biota. The mean concentration of EOBr in harborporpoise (1700 ng/g ww) from the Baltic Sea ( 16  ) wascomparabletoconcentrationsintunaandalbatrossobservedin this study. However, concentrations of EOBr in marineorganisms in the present study were greater than those in Atlantic herring from the Baltic Sea (120 - 240 ng/g ww) ( 16  )and northern pink shrimp from the North Atlantic Ocean(60 - 1030ng/gww)( 19  ).Overall,thereportedconcentrationsofEOBrintheorganismsanalyzedinthisstudyrangedfromof 60 to 6100 ng/g ww. Similar variation in EOBr concentra-tions has been reported for tissues of terrapins, birds, andfish collected from coastal waters of Georgia, U.S., whichranged from 110 to 3700 ng/g ww. Although the underlying reasonsforthisvariationareunknown,ithasbeensuggestedthat concentrations of EOBr are species- and location-spe-cific ( 4  ).Concentrations of bromine associated with identifiedEOBr compounds are presented (Figure 2 and Table 1). The C  EOBr  ) C  Br in extract  ×  10 W    wet ×  1000 (1) C  NEBr  )  C  Br in RSP  ×  (1  -  Wat %  )  ×  (1  -  Lipid %  )  ×  1000(2) C  TBr  )  C  EOBr  +  C  NEBr  (3) C  known EOBr  ) ∑ i  ) 1 m  ( 80  ×  N  i  MW  i  ×  C  i  )  (4) 6070  9  ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 44, NO. 16, 2010  proportion of Br contributed by MeO-PBDEs was relatively largeintuna(0.31 ( 0.10ng/gww)andalbatross(0.65 ( 0.85ng/g ww). The greatest contributions of OH-PBDEs toidentified EOBr were found in albatross (0.34  (  0.24 ng/g  ww),andthegreatestbrominecontributionsfromBRPswereobservedintuna(0.48 ( 0.21ng/gww).Inthesetwospecies,thepredominantcongenersofMeO-PBDEs,OH-PBDEs,andBRPs were 6-MeO-BDE-47, 6-OH-BDE-47, and BRP-24,respectively. Previous studies have demonstrated that thesecompounds srcinate primarily from natural synthesis by marine algae ( 11, 12, 20, 21 ). Thus, most of the identifiedcompoundscontributingtoconcentrationsofidentifiedEOBrin tuna and albatross are from naturally occurring com-pounds. Contributions of Br from the naturally occurring MeO-PBDEs (0.014 ( 0.01 ng/g ww) and OH-PBDEs (0.004 ( 0.005 ng/g ww) were small in polar bear, relative to thosein tuna and albatross. The relative contributions of orga-nobromine compounds of human srcin in polar bear liver(PBDEs:0.49 ( 0.16ng/gwwandPBBs:0.34 ( 0.29ng/gww) weregreaterthanthoseintunaoralbatross.Profilesofrelativeproportions of identified compounds including PBDEs andPBBs in polar bears were dominated by BDE-47 and PBB-153, respectively. Similar profiles of PBDEs and PBBs havebeen reported for other marine organisms ( 17, 22  ). Becausepoint sources play only a minor role in regional contamina-tion of the Arctic marine ecosystem ( 23  ), the relatively greatconcentrations of PBDEs and PBBs in polar bear are likely due to atmospheric transport and deposition of theseanthropogenic compounds ( 24  ). Proportions of Identified Compounds in EOBr andTBr.  AmassbalanceanalysisofBrcompositionshowedthatNEBr accounted for a major proportion of TBr (72 ( 24% to90  (  4%) in all samples (Figure 3). Similar to the resultsreported here, the major proportions of total fluorine (TF)foundinhumanbloodanddolphinliverswerenonextractableorganic fluorine (NEOF) and inorganic fluoride (IF) ( 5, 8  ).The EOBr accounted for a relatively small fraction of TBr ineach species, ranging from 10 ( 4% in tuna to 28 ( 24% inpolar bear. Although the contributions of EOBr to TBr inpolarbearliverwerevariable(2 - 53%),thelargepercentagesare comparable to the contributions of extractable organicfluorine (EOF) to TF measured in livers of marine mammalsin Hong Kong such as the Indo-pacific humpback dolphin:58%, and finless porpoise: 27% ( 8  ).Identified EOBr accounted for only 0.08 - 0.11% and0.008 - 0.012%ofEOBrandTBr,respectively(Figure3)inthethree species, all of which are at the top of the food chain.ContributionsofidentifiedEOBrtothetotalconcentrationsofEOBrweresmallcomparedtotheratiosofidentifiedEOFto total EOF (Indo-pacific humpback dolphin: 30%, finlessporpoise: 30%, and human blood: higher than 60%; refs  5,8)   and identified EOCl to total EOCl (fish: 5 - 25%; blue crab:35%, birds: 1 - 14%, and terrapin: 4.2%; refs  4, 14)  . The smallproportion of identified EOBr contributing to total EOBrconcentration is probably due to the diversity of naturally occurringorganobrominecompounds.Previousstudieshaveshowntheexistenceofnearly3200knownnaturallyoccurring organohalogen compounds in the environment, with morethan 1600 containing bromine ( 25  ). The predominance of naturally occurring organobrominated compounds is likely a result of the relatively low energy requirement for theformation of the C - Br bond. The stronger halogen - carbonbonds are less likely to be derived from naturally biologicalprocesses. The relationship between identifiable syntheticand unidentified organohalognes is given in Figure 4. Sincethe C - F bond is relatively strong, it is much less likely to beformed naturally and there are likely to be fewer F atoms innaturally occurring organic molecules. Therefore, most of theorganicallyboundfluorineisattributabletoidentifiable,synthetic, per- and polyfluorinated compounds. FIGURE 3. Relative contribution (%) of identified EOBr, EOBr,and NEBr to TBr concentration in livers of polar bear, alba- tross, and tuna from remote marine locations.FIGURE 4. Relationship between carbon - halogen bond ener-gies and contributions of identified anthropogenic organohal-ogens to extractable organic halogens. Bond energies werereferenced from  26  .FIGURE 2. Concentrations of major organic brominated com-pounds detected in liver samples collected from species in-habiting remote marine locations. VOL. 44, NO. 16, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY   9  6071  Estimating the Major Organobromine Compounds inEOBr.  There is a variety of synthetic and natural organo-brominatedcompoundsthatwerenotquantifiedinthisstudy that could have contributed to the EOBr of these samples(Table2).Sincethemassesofsamplesavailableforthisstudy  werelimitedandstandardsarenotavailableformanyoftheclasses of brominated compounds that could have contrib-uted to the EOBr, an assessment of the potential for thoseunquantifiedcompoundstocontributetotheEOBrwasmadefrominformationavailableintheliterature(Table2).PBDEs were generally the predominant compounds among bro-minated flame retardants, which is also consistent with thefact that they are used in the greatest quantities globally. Among naturally occurring brominated compounds, con-centrations of MeO-PBDEs, BRPs, and polybrominatedhexahydroxanthene derivatives (PBHDs) were generally greaterthanotherbrominatedcompoundsofnaturalsrcin( 28  - 30  ).Inthecurrentstudy,PBHDswerenotanalyzed,butconcentrations of PBHDs have been reported to be as greatas 5000 ng/g lipid weight (lw) in some deep-ocean fishes( 28  ).SinceauthenticPBHDstandardswerenotcommercially available, PBHDs were identified and quantified based onpreviouslyreportedmethods( 28  ).WhileMeO-PBDEsinthesample extracts can be detected by GC-EI-MS, no obviouspeaks that would have corresponded to masses of PBHDs wereobserved(SupportingInformationFigureS1).ThisresultsuggeststhatconcentrationsofPBHDsinthesamplesstudied were not significant contributors to TBr. The presence of PBHDs and other organobromine compounds were furtherstudied by GC-ECNI-MS, and no brominated compounds with concentrations greater than approximately 1 ng/g ww could be detected (Supporting Information Figure S2). Inaddition, concentrations of the detected organobrominecompounds reported previously were very small compared with those of EOBr (Table 2). Including the estimatedconcentrationsoftheseadditionalbrominatedcompounds,the identified proportion of the EOBr would not exceed 1%.Brominatedfattyacids(BFAs)couldbethepredominantcompoundsinEOBr,sinceBFAshavebeenreportedtooccurat concentrations ranging from 2.2 to 82  µ g/g ww in marinefishes and invertebrates ( 34  ). These concentrations arecomparable to those of EOBr determined in this study (1.1 - 2.8  µ g/gww).However,reportedconcentrationsofBFAs werebasedontheanalysisofbrominecontent.Asoneofthemost interesting groups among the naturally occurring halogen compounds, BFAs comprise a relatively large anddiverse class of compounds ( 35, 36  ). BFAs with differentstructures have been identified in marine algae and inver-tebrates,andsomecompoundscontainasmanyas28carbonatoms ( 35, 36  ). However, none of the studies has attemptedto quantify BFAs. In the current study concentrations of saturated BFAs (C2 - C21) were estimated by use of GC-EI-MSafterderivatizationoftheextractswith N  -methyl- N  -(tert-butyldimethylsilyl) trifluoroacetamide with 1%  t  -BDMS-chloride (MTBSTFA) (FigureS3 in Supporting Information).However, the chain lengths of BFAs in marine organisms were generally greater than 16 ( 35, 36  ), and standards forBFAs of this chain length are not commercially available. A numberofpossiblepeakswithrelativelygreatconcentrations were observed (Figure S4 in Supporting Information), but without authentic standards, it was difficult to accurately identify or quantify the individual BFAs. Further studiesshould focus on the analysis and potential effects of thesecompounds. Acknowledgments The research was supported by a Discovery Grant from theNational Science and Engineering Research Council of Canada (Project 326415-07) and a grant from WesternEconomic Diversification Canada (Projects 6971 and 6807).J.G. was supported by the Canada Research Chair programand an at large Chair Professorship at the Department of Biology and Chemistry and State Key Laboratory in MarinePollution, City University of Hong Kong. We acknowledgethe support of an instrumentation grant from the CanadaFoundationforInfrastructure.WethankThomasEvans,U.S.Fish and Wildlife Service, Anchorage, Alaska, for providing polar bear livers. Supporting Information Available Detailed information on chemicals, standards, instrumentanalysis, and analysis of saturated brominated fatty acids;GC-EI-MS and GC-NCI-MS chromatography of sampleextracts. This material is available free of charge via theInternet at http://pubs.acs.org. TABLE 2 .  Concentrations of Organobromine Compounds Reported in Previous Studies  a brominated flame retardants originated from both sources naturally occurring brominated compoundsample ref PBDEs PBBs TBBPA HBCD PBDD/Fs BRPs OH-PBDEs MeO-PBDEs PBHDs TBA MHC-1 BRI glaucous gull  18   1325 21.9 26.5 54.3polar bear  18   533 N.D. N.D. N.D.eel  27   24.6 0.1 N.D. 57.5cormorant  9   1419 14.4 0.1predatory birds  17   1753 63.0 N.D. - 0.26deep sea fish  28   16.9  < 1.5 28.9 530 0.3 9.7deep sea fish  28   5.1  < 1.5 6.5 7040  < 0.2 0.6food web  29   6.4 - 115.4 1.0 - 3.0 0.7 - 110.1 4.7 - 146 11.7 - 30.1 0.1 - 1.6wild tuna  30   58 - 74 134 - 167 3580 - 5241 3.1 - 4.2 26 - 30whale oil  31  0.1 0.008sediment  32   13.3 - 360.8 0.4 - 118fish andmussels  33   < 5 - 1140  < 1 - 3tuna  b   5.7 0.2 18.8 0.6 13.4albatross  b   2.6 0.6 0.4 6.7 12.3polar bear  b   11.0 0.8 2.1 0.6 0.4 a  (ng/g lw (lipid weight). Number underlined indicates the predominant brominated compounds detected. Theconcentrations of EOBr in tuna, albatross, and polar bear in current study were 23 000, 17 000, and 40 000 ng/g lw,respectively. TBBPA: tetrabromobisphenol A; HBCD: hexabromocyclododecane; PBDD/Fs: polybrominated dibenzo-p-dioxins and dibenzofurans; PBHDs: polybrominated hexahydroxanthene derivatives; TBA: tribrominated anisole; BRI:brominated indole. Locations of references: ( 18  ), Norwegian Arctic; ( 27  ), Irish waters; ( 9  ), Japan; ( 17  ), Norway; ( 28, 30  ), and( 33  ), Mediterranean Sea; ( 29  ), Sydney Harbour; ( 31 ), historical sample; ( 32  ), North and Baltic Sea.  b  Current study. 6072  9  ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 44, NO. 16, 2010
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