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Journal of Hazardous Materials 277 (2014) 127–133

Contents lists available at ScienceDirect

Journal of Hazardous Materials

j o ur nal ho me pa ge: www.elsev ier .com/ locate / jhazmat

ioaccumulation of persistent organic pollutants in strandedetaceans from Taiwan coastal waters

ung Chi Koa,b,∗, Nien-Ying Wea, Lien-Siang Chouc

Institute of Marine Biodiversity and Evolutionary Biology, National Dong-Hwa University, Checheng, Pingtung, TaiwanNational Museum of Marine Biology and Aquarium, Checheng, Pingtung, TaiwanInstitute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan

i g h l i g h t s

PBDEs were first measured in stranded dolphin in Taiwan.PBDE levels and congener profile correlated to dolphin gender, tissue type and body length.Predominant compound BDE-154 and BDE47 suggested the metabolic capability of cetacean for PBDEs.

r t i c l e i n f o

rticle history:eceived 2 September 2013eceived in revised form4 November 2013ccepted 29 December 2013vailable online 4 January 2014

eywords:olphins

a b s t r a c t

This study focuses on analyzing PBDEs in the liver, muscle, and blubber tissues of stranded dolphins(Stenella attenuate) on the Taiwan coast to determine and compare the PBDE levels and distributionsamong tissue types. Total concentrations of 19 PBDEs (�PBDE) in male dolphins (9.97 to 436 ng/g fat)were significantly higher than in female animals (2.73 to 89.5 ng/g fat), implying gender variation inbioaccumulation and the possibility of generation transfer from mother to fetus during pregnancy. Thelevels of contamination varied among tissue type; contamination was higher in blubber than that inmuscle or liver, suggesting a possible transformation and redistribution of these compounds in bodyburden. Aside from gender and tissue type, �PBDE concentrations also significantly correlated with

BDEsioaccumulationissue typelubber

body length, an indicator of dolphin age. PCA analysis results showed no significant difference in PBDEcongener pattern distributions in blubber tissues, indicating that blubber may be the final storage ofcontaminants in cetaceans, and that bioaccumulation of PBDEs may be dependent on chemical properties.BDE-154 and BDE-47 were the predominant PBDE congeners in stranded dolphins, and their correlationwith body length suggests the significant metabolic depletion of BDE-154 in this species and possibleexposure to both penta-BDE and octa-BDE mixtures.

. Introduction

Cetaceans are the top predators in marine ecosystems, and arerone to accumulating high concentrations of persistent organicollutants (POPs) [1–3], especially in contaminated coastal waters4]. Thus, POP levels and distribution in cetaceans are impor-ant indicators of the contamination status and its environmental

mpact in coastal waters. Furthermore, prior investigation indi-ated that even relatively low concentrations of POPs can causeegative effects on dolphins, including immune system impairment

∗ Corresponding author at: National Museum of Marine Biology and Aquarium National Dong-Hwa University, Institute of Marine Biodiversity and Evolutionaryiology, 2, Houwan Road, Checheng, Pingtung 944, Taiwan. Tel.: +886 88825039;

ax: +886 88825066.E-mail addresses: ko@nmmba.gov.tw, ko@mail.ndhu.edu.tw (F.C. Ko).

304-3894/$ – see front matter © 2014 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.jhazmat.2013.12.057

© 2014 Elsevier B.V. All rights reserved.

[5], anemia, and problems with thyroid hormone homeostasis [6].However, little is known about the impact of these POPs in termsof bioaccumulation, and whether they cause of cetacean stranding.

Polybrominated dipheyl ethers (PBDEs), recognized as emerg-ing contaminants, are a group of POPs used as flame-retardantsin textiles, paints, furniture, electronic circuit boards, and plasticswhich have been heavily developed and produced in Taiwan forthe last few decades. Several investigations in Taiwan coast sed-iments [7,8] and estuarine fishes [9] have found detectable PBDElevels. Although PBDEs are listed in Stockholm Convention and useof PBDEs has already been terminated in many countries, largeamounts of PBDEs have already been released into the global envi-ronment. As a result of their environmental persistence and high

production volume, PBDEs have become ubiquitous global contam-inants [1,10–13].

Recent attention has been focused on the potential bioaccu-mulation of PBDEs in marine ecosystems, especially the highly

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28 F.C. Ko et al. / Journal of Hazar

rominated PBDEs (high molecular weight) and the persistentubstituted chemicals. While direct exposure to commercialDE mixtures is assumed to be the main source of PBDEptake/accumulation in biota, it is plausible that debrominationf parent congeners in various tissue of marine organisms mayontribute to the loading of persistent BDEs in marine food webs14–16]. Many studies have reported on the occurrence and dis-ribution of PBDEs in marine ecosystems and concluded that theeographical and temporal variations of PBDEs in marine mammalsre affected by many factors, including exposure to contaminantource, species, gender, and age, but little information is avail-ble on the variation of fate and distribution of these persistentompounds in different tissues of top predators. Isobe et al. [17]eported that PBDE concentrations in striped dolphins collectedrom 1978 to 2003 in Japan showed no significant differencesetween blubber, liver and muscle. In contrast, other studiesemonstrated varying PBDE concentrations (lipid based) amonghe different tissues in the same individual [18,19]. Thus, tissue-pecific distribution of PBDEs in cetaceans remains an unresolvedssue.

Monitoring the PBDE levels in tissues of dolphins is necessaryo understand the exposure and the risks posed by toxic con-aminants. As PBDE values have not been investigated for marine

ammals from the Taiwan coast, 19 PBDE congeners were inves-igated in greater detail in the mass-stranded species (Stenellattenuate), a common species in Taiwan waters. Blubber, musclend liver tissues of stranded dolphins were analyzed in this study.he primary objectives of this study were to report the levels ofBDEs in dolphin blubber, muscle and liver, to assess factors affect-ng these concentrations, to compare PBDE levels to concentrationsreviously reported in the other areas, and to evaluate the PBDEongener distributions in different tissue types to gain insight intoetabolic and accumulation pathways for PBDEs in these stranded

olphins.

. Materials and methods

.1. Sample collection and preparation

Eight pantropical spotted dolphin (S. attenuate) were collectedn the northern Taiwan coast from stranding incidents (n = 8)ccurring in September, 2007. Samples were collected from dol-hins stranded in good condition. All 8 stranded dolphins wereead when they were discovered. Within 12 h post-mortem, wholenimal samples were placed on ice and transported to the labora-ory where standard length, weight and sex were recorded. Afteriometric measurements, the animals were dissected; the bubblernd spinalis (muscle) samples were taken from the left side in frontf the dorsal fin. All the samples were stored in baked glass jars androzen at −20 ◦C until analysis.

.2. Extraction and chemical analysis

Freeze-dried tissue samples were extracted withichloromethane at 100 ◦C and 2000 psi in a pressurized fluidxtractor (ASE-300, Dionex, USA). The programmed extractioneating and static times were both 5 min and three extractionycles were used for each sample. Lipids and other matrix inter-erences were removed from each extract by acetonitrile. Prior toipid removal, a subsample of each extract was used for gravimetricipid content determination [20]. The resulting organic phase was

educed to approximately 5 mL using a rotary evaporator (Buchi-3000), and passed through a glass column packed with 8 g of 2.5%w/v) deactivated florisil and baked anhydrous sodium sulfate. Therganic portion was eluted twice with 35 mL of petroleum ether.

aterials 277 (2014) 127–133

The first 35 mL of eluent was discarded, while the second 35 mL ofeluent was collected and concentrated to approximately 5 mL byrotary evaporation. The volume of extract was further reduced toless than 1 mL under a gentle stream of nitrogen (99.99%; purifiedby passage through an activated carbon column).

The sample analysis was performed using a Varian CP-3800gas chromatograph coupled with a Model 320 mass spectrome-ter using negative chemical ionization (NCI) in the selected ionmonitoring (SIM) mode. A VF-5MS (10 m, id = 0.53 mm, 0.25 �mfilm thickness) rapid capillary column was used for the determi-nation of PBDE congeners. The initial column oven temperature(80 ◦C; held for 0.5 min) was increased to 210 ◦C at 30 ◦C/min (heldat 210 ◦C for 2 min), then increased to 310 ◦C at 25 ◦C/min (heldat 310 ◦C for 3.17 min). Automatic injection of sample (1 �L) wasconducted in the split mode. The temperature of both the injec-tor and detector was 300 ◦C. Quantification of PBDEs was carriedout with the internal standard calibration procedure. The con-geners in the sample extracts were determined based on theirchromatographic retention times relative to the internal standard,PCB-204; 2,2′,3,4,4′,5,6,6′-octachlorobiphenyl (AccuStandard, NewHaven, CT, USA).

2.3. QC/QA

During each analysis series (8 samples), quality assurancepooled samples were examined. Within the scope of the analysis,duplicated Na2SO4 spiked PBDEs and method blanks were exam-ined parallel to the tissue samples in order to detect potentialcontamination during sample processing. Method detection limits(MDL) were calculated by the average blanks of each congener plusthree times the standard deviation (Table 1). Analytical accuracywas guaranteed through regular analysis of NIST Standard Refer-ence Materials (SRM1945) of organics in whale blubber. Replicatealiquots of dolphin blubber, muscle, and liver samples were ana-lyzed for quality control. All data met the QA/QC specifications.Recoveries measured for the spiked standards ranged between 70%and 101% (Table 1). Total PBDE (�PBDE) represents the sum of 17BDE congeners. Data are presented on a fat-weight basis.

2.4. Statistics

Statistical analyses were performed using Minitab 11.0. Concen-trations below the level of detection (Table 1) were treated as zerofor further statistical analysis. To compare concentrations amongtissues from female and male dolphins, multivariate analysis ofvariance (MANOVA) was used to compare mean contaminant con-centrations between the eight individual samples, including fivemales and three females. Using contrasts (Turkey-Kramer), indi-vidual analyses of variance (Welch’s ANOVA for unequal variances)were conducted to determine which compound concentrationswere significantly different among tissues. MANOVA was also usedto compare concentrations of 13 dominant PBDE congeners amongthe tissue classes. Relative proportions of individual PBDE con-geners to the total PBDEs (pattern of congener) among the tissuetypes were examined using principal component analysis (PCA).

3. Results and discussion

3.1. PBDE concentrations in pantropical spotted dolphins

Total PBDE (�PBDE) concentrations in the stranded pantropi-cal spotted dolphin ranged from 1.74 (female muscle) to 436 ng/g

fat (male blubber), with an overall mean of 86.5 ± 125 ng/g fat(Table 2). In general, the variation in the mean concentration ofcontaminants in marine mammals may be due to the fluctuation inlipid contents and compositions in organisms of different species,

F.C. Ko et al. / Journal of Hazardous Materials 277 (2014) 127–133 129

Table 1The method detection limits (MDL) and spiked recovery (%) of the analyzed PBDE congeners.

PBDEs CAS no. MDL (ng) Recovery (%)

BDE002 3-Bromodiphenyl ether 0.04 86 ± 12BDE015 4,4′-Dibromodiphenyl ether 2050-47-7 0.10 89 ± 15BDE017 2,2′ ,4-Tribromodiphenyl ether 0.03 85 ± 14BDE028 2,4,4′-Tribromodiphenyl ether 41318-75-6 0.04 95 ± 13BDE71 2,3′ ,4′ ,6-Tetrabromodiphenyl ether 0.06 90 ± 13BDE47 2,2′ ,4,4′-Tetrabromodiphenyl ether 5436-43-1 0.07 95 ± 14BDE66 2,3′ ,4,4′-Tetrabromodiphenyl ether 189084-61-5 0.10 94 ± 16BDE100 2,2′ ,4,4′ ,6-Pentabromodiphenyl ether 189084-64-8 0.04 97 ± 14BDE99 2,2′ ,4,4′ ,5-Pentabromodiphenyl ether 60348-60-9 0.02 97 ± 13BDE85 2,2′ ,3,4,4′-Pentabromodiphenyl ether 182346-21-0 0.04 86 ± 12BDE154 2,2′ ,4,4′ ,5,6′-Hexabromodiphenyl ether 207122-15-4 0.46 93 ± 13BDE153 2,2′ ,4,4′ ,5,5′-Hexabromodiphenyl ether 68631-49-2 0.11 92 ± 13BDE138 2,2′ ,3,4,4′ ,5-Hexabromodiphenyl ether 182677-30-1 0.08 81 ± 11BDE183 2,2′ ,3,4,4′ ,5,6′-Heptabromodiphenyl ether 207122-16-5 0.07 101 ± 19BDE190 2,3,3′ ,4,4′ ,5,6′-Heptabromodiphenyl ether 0.09 89 ± 13BDE203 2,2′ ,3,4,4′ ,5,5′ ,6-Octabromodiphenyl ether 0.23 97 ± 17BDE205 2,3,3′ ,4,4′ ,5,5′ ,6-Octabromodiphenyl ether 0.04 70 ± 12BDE206 2,2′ ,3,3′ ,4,4′ ,5,5′ ,6-Nonabromodiphenyl ether 0.36 77 ± 3BDE209 Decabromodiphenyl ether 1163-19-5 0.42 83 ± 12

Table 2Comparison of total PBDE levels in blubber of different species dolphin from different areas.

Locations (country) Dolphin species Sampling year(s) Tissues Gender Total PBDE (ng/g fat) References

Taiwan Pantropical spotted dolphin(Stenella attenuate)

2007 Muscle Female 4–9 This studyLiver Female 3–7Blubber Female 15–89Muscle Male 15–69Liver Male 10–229Blubber Male 31–436

Korea Long-beaked common dolphina 2006 Blubber Female 140–2300 [21]Korea Long-beaked common dolphina 2006 Blubber Male 200–3100 [21]Japan Pacific white-sided dolphinb 1999 Blubber 100–1200 [22]Japan Striped dolphinc 1978–1992 Blubber Male 13–660 [17]Japan Striped dolphinc 2003 Blubber Male 520–850 [17]Japan Striped dolphinc 2003 Blubber Female 84 [17]Hong Kong Indo-pacific humpback dolphind 1997–2001 Blubber Male 280–6000 [22]Hong Kong Indo-pacific humpback dolphind 2000–2001 Blubber Female 670–1600 [23]Philippines Spinner dolphine 1996 Blubber 20–64 [22]India Indo-pacific humpback dolphind 1992 Blubber 10–12 [22]India Spinner dolphine 1990–1992 Blubber 6–8 [22]India Irrawaddy dolphinf 2000–2001 Blubber Female 2.5 [18]India Irrawaddy dolphinf 2000–2001 Blubber Male 18 [18]European seas Common dolphing 2001–2003 Blubber Female 442–758 [24]UK Bottlenose dolphinh 1995–2001 Blubber Male 850–9680 [25]UK Bottlenose dolphinh 1995–2001 Blubber Female 4210–11,560 [25]US Bottlenose dolphinh 2002–2005 Blubber Male 1290–2740 [26]US Bottlenose dolphinh 2002–2005 Blubber Female 82.9–195 [26]US Bottlenose dolphinh 2000–2002 Blubber Male 1497–2710 [19]US Bottlenose dolphinh 2002–2007 Blubber Female 217–2557 [19]US Bottlenose dolphinh 2009 Blubber Male 1390–1750 [27]US Bottlenose dolphinh 2009 Blubber Female 151–1500 [27]

“This study” means the data are from the present study, which is not listed in the references.a Long-beaked common dolphins (Delphinus capensis).b Pacific white-sided dolphin (Lagenorhynchus obliquidens).c Striped dolphin (Stenella coeruleoalba).d Indo-Pacific humpback dolphin (Sousa chinensis).e Spinner dolphin (Stenella longirostris).f

gaamfcdir

Irrawaddy dolphin (Orcaella brevirostris).g Common dolphin (Delphinus delphis).h Bottlenose dolphin (Tursiops truncates).

enders, stages of growth, and health conditions. The sourcesnd distribution of the contaminants may also be a critical factorffecting the concentration levels accumulated in the marine mam-als. Blubber, a modified form of adipose tissue in cetaceans, is

requently used as an indicator to estimate the contaminant bioac-

umulation status. The total PBDE levels in blubbers of the strandedolphins from different regions were summarized and compared

n Table 2. The PBDE levels in the stranded S. attenuate in this study,anging from 15.4 to 89.5 ng/g fat in female and 30.9 to 436 in male,

were one to two orders of magnitude lower than those detected inthe other species of dolphins from European seas [24], UK east-ern coast [25] and the US coast including VA, NC and FL [19,26,27].This comparison implies that relative to Europe and the US, thelevel of PBDE contamination in Taiwan is lower. The investiga-

tion results coincide with the previous study from the sedimentsamples [8].

The PBDE levels in the dolphin blubber in this study were com-parable to those reported from some areas in Southeast Asia, such as

130 F.C. Ko et al. / Journal of Hazardous Materials 277 (2014) 127–133

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ig. 1. Mean (·), median (—), interquartile distance (box) and extreme values (ver-ical lines; |) for the total PBDE concentrations in each tissue of dolphins.

ndia and the Philippines (Table 2), but still relatively low comparedo Japan, Hong Kong and Korea, indicating that the market demandor PBDE compounds might be higher in developed countries.urther investigation in this region is necessary to assess the PBDEources, distribution, transport, and its impact to the ecosystem.

Fig. 1 demonstrates that �PBDE concentrations in male dolphinsranging from 9.97 ng/g fat in liver to 436 ng/g fat in blubber) wereignificantly (p < 0.001) higher than in female dolphins (rangingrom 2.73 ng/g fat in liver to 89.5 ng/g fat in blubber). The loweroncentrations of PBDEs in female dolphins might be caused byhe transfer and elimination of PBDEs through pregnancy and lac-ation. For both male and female dolphins, �PBDEs were mainlyccumulated in the blubber due to the dominant levels of tallow inlubber, which may act as the final storage location of contaminants

n cetaceans. Although the PBDE concentrations have been normal-zed by lipid contents, the higher levels of �PBDE still present in

lubber than the other tissues and the �PBDE levels, both lipidormalized and wet weight based, linearly correlate to the lipidontent (Fig. 2). The result might be due to differing lipid dynamics

ig. 2. Correlation of �PBDE concentrations ((A) wet-weight based; (B) lipid nor-alized) and the lipid contents (%).

Fig. 3. Correlation of �PBDE concentrations and the dolphin body lengths. (A) maledolphins, (B) female dolphins.

with varying compositions and characteristics for bioaccumula-tion of organic contaminants [28]. The results showed that PBDEsmay have different partition behaviors during lipid metabolismin each type of tissue. It is an important issue to investigate thetissue-specific distribution of PBDE in stranded dolphins to furtherevaluate the toxic effect of POPs on cetaceans.

Fig. 3 illustrates the correlation between �PBDE levels and thebody length, which represents the growth stage/age of the dol-phins. It is clear that the bioaccumulation of �PBDEs in maledolphin increased with the body length, especially in male blub-ber (R2 = 0.85; Fig. 3). However, the linear relationship betweenthe �PBDE levels (in muscle and liver) and body lengths was notclear for female dolphins, which may be due to limited data or con-founded by the exclusion of PBDEs through pregnancy or lactation.

3.2. PBDE congener profiles in dolphin

Of the 19 BDE congeners detected in pantropical spotted dol-phins of this study, 13 di- through hexa-BDEs (BDEs-15, -17, -28,-71, -47, -66, -100, -99, -85, -54, -153, -138, and -183) accounted for92–98% of the PBDE content. Therefore, these 13 congener patternsamong tissues were analyzed using principal component analysis(PCA). PCA of the PBDE congener patterns produced two compo-nents (27.0% and 23.5%) that describe 50.5% of the variance in eachtissue (Fig. 4). The PBDE compound patterns in the dolphin sam-ples of this study can be placed in two gender-related groups. Bothfemale and male samples were dominated by BDE-47 and BDE-154(Fig. 5). In one male liver sample, there was an unusual distributionof BDE-66 that paralleled a deficiency in BDE47 (Fig. 5B). The causefor this exception was unclear.

BDEs-47, -99, -100, -153 and -154, are generally dominant inbiota worldwide and appear to have a high potential for bioac-cumulation. However, congener profiles among the gender and

tissue types were variable (Fig. 5), reflecting tissue- and gender-specific differences in uptake and metabolism/excretion of theindividual BDE congeners [26,27]. BDE-47 was the dominant con-gener in many biota samples, accounting for more than half of

F.C. Ko et al. / Journal of Hazardous M

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ig. 4. Comparison of PBDE congener patterns analyzed by PCA. (Solid makers: maleolphins, blank makers: female dolphins).

he total PBDE content. In comparison, BDE-99 constituted 50% ofhe technical penta-BDE mixture, yet contributed much less to theotal in the dolphin (<10%). Metabolic debromination of BDE-209as been demonstrated in freshwater fish, resulting in the forma-ion of less-substituted BDEs (hexa- through nona-BDEs) that havehe potential to be more persistent and bioaccumulative than thearent compound [14,16,29]. In laboratory exposure studies, sig-ificant debromination of BDE-99 was observed in the intestinalract of common carp (Cyprinus carpio), resulting in the conversionf BDE-99 to BDE-47 [14]. In addition to debromination, prefer-

ntial excretion of BDE-99 was suggested as a reason for lowerccumulation of BDE-99 relative to BDE-47. In this study, no dif-erences in BDE-99 abundance relative to BDE-47 were apparentetween analyzed samples, implying the significant and constant

ig. 5. Congener patterns of PBDEs in muscle (A), liver (B), and blubber (C) of male dolphi

aterials 277 (2014) 127–133 131

debromination of BDE-99 to BDE-47. Penta-BDE-85 and BDE-100were relatively abundant, accounting for 20–34% and 10–15%,respectively, of the total PBDE mass. In the male dolphins, BDE-154 contributed 23–31% of the total PBDE content in blubber,tetra-BDE-47 contributed 16–24%, and the penta-BDEs-100 and-85 contributed 10–15% and 8–14%, respectively (Table 3). Inter-estingly, BDE-154 was more abundant in dolphin tissues than theother BDE congeners in this study. This congener is present at only2.7–4.5% in technical mixtures of penta-BDE (Table 3) [30] and wasidentified as a specific debromination product of BDE-209, implyinga possible source of deca-PBDE on Taiwan coast. Previous researchproposed that BDE47 in most of biota samples may be dechromi-nated from BDE99 along with BDE154 [16]. Fig. 5 indicated thatBDE47 was more dominant in male dolphins (up to 20%) than infemale dolphins (10%). In contrast, BDE 154 was more dominant infemale dolphins (40%) than in male dolphins (20%), implying thatthe dechromination process of BDE154 might be elevated in maledolphins, causing the increased bioaccumulation of BDE47.

Overall, the dolphins contained a greater proportion of tetra-and penta-BDEs in their tissues than were present in technicalpenta-BDE mixtures or in fish tissues. In studies involving the trans-fer of PBDEs from fish to marine mammals, BDE-85 has rarely beenreported [31–34]. This congener is reportedly one of the breakdownproducts from anaerobic transformation of an octa-BDE technicalmixture [35], and may be indicative of reductive debrominationof higher brominated BDEs in marine biota. Many PBDEs are ableto bioaccumulate and biomagnify in marine food web, resulting inmarine cetacean blubber with higher concentrations of contami-nants than those found in the cetacean’s prey. The high proportionof hexa-BDEs-153 and -154 in dolphin blubber reflect the lackof or weak metabolic capacity for these congeners, due to theirmeta–para-substituted structures.

A recent study [36] reported a lack of biomagnification of PBDEs

from fish to harbor seals, suggesting that marine mammals canmetabolize several PBDE congeners. In view of the increasing globaluse of this brominated flame retardant compound, more studieson the loading, kinetics, and biomagnification potential of PBDEs in

ns and in female dolphins (D). Error bars are standard deviations of each congener.

132 F.C. Ko et al. / Journal of Hazardous Materials 277 (2014) 127–133

Table 3Each BDE proportion (%) of the total PBDE in technical mixtures and dolphin tissues.

Commercial mixtures Male dolphin Female dolphin

PentaBDE OctaBDE Muscle Liver Blubber Muscle Liver Blubber

BDE02 nd.a nd. nd. nd. nd. nd.BDE15 nd.–7.5 1.1–16.3 0.4–1 nd. nd. 0.1–3.3BDE17 3.4–6.7 1.3–6.2 4.8–5.8 3.2–5.6 3.3–4.2 3.4–4.5BDE28 0.5–2 0.4–2.2 1.5–4.7 1.5–3.7 2.6–3.6 2.3–2.9BDE71 0.8–12.5 0.9–4.8 1.5–10.9 1.9–3.5 4.5–6.2 4.8–7.3BDE47 38–42 12–28.3 6.6–23.3 16.3–23.9 6.9–16.1 11.2–13.3 11.9–13.2BDE66 0.7–2.3 1.2–56 1.3–3.6 nd. 3–3.6 3.1–4BDE85 2.2–3 9.9–14.4 5.8–13 8.2–14 20.3–33.8 19.8–20.7 17–18.2BDE99 45–49 2.2–6.8 1–4.4 3.4–7.6 1.9–3.9 2.5–3.3 2.7–2.8BDE100 7.8–13 7.5–12.4 4.2–13.1 10–14.7 5.2–8.4 7.1–7.6 6.8–7.4BDE138 nd. 0.1–0.7 0.1–0.2 nd. nd. 0.5–0.7BDE153 5.3–5.4 0.15–8.7 4.1–8.1 1.6–10.4 4.3–9.6 3.8–6.8 4.9–5.9 6.3–7.2BDE154 2.7–4.5 0.04–1.1 21.5–27.5 7.3–34.3 22.5–31.1 25.1–44.8 35.1–36.9 32.3–34.1BDE171 0.17–1.8BDE180 nd–1.7BDE183 13–42 nd.–16.7 0.4–8.3 0.1–3.2 nd. nd 1.4–2.1BDE190 nd. nd. nd. nd. nd. nd.BDE196 3.1–10.5BDE197 11–22BDE203 4.4–8.1 nd. nd. nd. nd. nd. nd.–0.3BDE205 nd. nd. nd. nd. nd. nd.BDE206 1.4–7.7BDE207 11–22 nd. nd. nd. nd. nd. nd.

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BDE209 1.3–50 nd. nd.

a nd = non-detectable (below MDL).

arine ecosystems are necessary. HeptaBDE-183, and hexaBDEs-53 and -154, considered the marker compound for the octa-BDEixture, were detected in the stranded dolphins (S. attenuate) in

his study. This finding indicates that components of the octa-BDEixture, which was principally used in molded parts of computers,

elevisions, car parts and other products, have contaminated thearine food web. Thus, while the presence of tetra- to penta-BDEs

n dolphin tissue probably represents direct exposure to compo-ents of the penta-BDE mixture, because of the short half-life ofigher molecular BDE congeners, occurrence of hepta- throughona-BDEs suggests the contribution of metabolic processes andecent exposure to octa- and deca-BDE mixtures to BDE levels37].

Although BDE-209 is usually the dominant BDE detected inarine sediments [38], it is often detected only at trace levels or

one at all in marine mammals, and there are relatively few reportsf BDE-209 in marine biota [15]. Experimental results indicate evi-ence of limited BDE-209 bioavailability in fishes (common carp;. carpio and rainbow trout; Oncorhynchus mykiss) from food in theorm of lower brominated metabolites [14,16]. Prey consumption

ay be the primary source of exposure for dolphins. Whether theack of biomagnification of BDE-209 is a result of a low assimilationate into blubber or metabolic depletion in the prey is unclear.

PBDEs have been shown to exert neurodevelopmental andndocrine-disrupting effects in animals [39,40]. In view of the his-orical and ongoing dispersal of PBDEs, there is a clear need for

ore information on the bioaccumulation and biomagnificationf PBDEs in marine food webs. BDEs-154 and -47 were the pre-ominant congeners in all the stranded dolphins analyzed in thistudy (Fig. 5), though commercial PBDE mixtures contain BDEs-154nd -47 in comparatively smaller amounts. Although about 80%f the PBDEs produced consist of deca-BDE, predominantly less-rominated congeners accumulate in cetaceans, possibly due toelective uptake into food chains or debromination of deca-BDE14,41]. These results are consistent with the known metabolic

apabilities of marine mammals concerning BDE-47 [42]. This is onef the paradoxes of PBDE accumulation that has not yet been clearlyxplained in mammals. Relative PBDE congener patterns in ani-als from different geographical locations may differ, mainly due

nd. nd. nd. nd.

to the differences in contaminant sources, contaminant transportpathways, diets, and species.

Similar patterns were found in the Taiwan coast and Japan. Thecongener profiles observed in finless porpoises, Dall’s porpoisesand melon-headed whales around Japan having proportionatelyless BDE-47 and more hexa-BDEs, were clearly different from thosein marine mammals reported from Europe and USA [43,44]. Thesestudies reported PBDE accumulation patterns with BDE-47 com-prising more than 60% of the total, whereas in the present study,the contribution by higher brominated congeners (BDE-154) washigher than BDE-47. The type of commercial PBDE mixture usedin these regions might elicit these differences in the accumulationprofiles. In the specimens from Taiwan, the percentage of hexa-BDEs was higher than in the same species collected near Hong Kong.This may be due to the different commercial mixtures of PBDEs usedin these two countries. This result might also suggest that PBDE pro-files in cetaceans are species-specific and independent of exposureamount and body burdens. Further studies on specific accumula-tion of PBDEs in high trophic animals through food chains shouldbe studied in detail.

4. Conclusions

Distribution of PBDE profile in stranded dolphins illustrated thecombination of bioaccumulation and metabolic transformation ofeach congener. PBDEs should be considered an increasing pollutionproblem in the Asia-Pacific region, which may be of great con-cern in the future. It is also imperative to identify potential sourcesof PBDEs and the toxicological risk for marine mammals, the toppredators of the marine ecosystem. Considering the widespreadand increasing concentrations of PBDEs in wildlife coupled withtheir persistency and global transport, there is a clear need for moreinformation on the bioaccumulation of PBDEs in marine food webs.

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