Chemosphere 77 (2009) 621–627

Contents lists available at ScienceDirect

Chemosphere

journal homepage: www.elsevier .com/locate /chemosphere

Persistent organochlorine pollutants and heavy metals in tissues of commonbottlenose dolphin (Tursiops truncatus) from the Levantine Basin of theEastern Mediterranean

Efrat Shoham-Frider a,*, Nurit Kress a, David Wynne b, Aviad Scheinin c, Mia Roditi-Elsar c, Dan Kerem c

a Israel Oceanography and Limnological Research, National Institute of Oceanography, Tel-Shikmona, P.O. Box 8030, Haifa 31080, Israelb Israel Oceanography and Limnological Research, The Yigal Allon Kinneret Limnological Laboratory, Israelc Israel Marine Mammal Research and Assistance Center, The Leon Recanati Institute for Maritime Studies and Department for Maritime Civilizations,The University of Haifa, Mt. Carmel, Haifa 31905, Israel

a r t i c l e i n f o a b s t r a c t

Article history:Received 26 May 2009Received in revised form 12 August 2009Accepted 27 August 2009Available online 20 September 2009

Keywords:CetaceansDDTPCBsMediterranean SeaTime trends

0045-6535/$ - see front matter � 2009 Elsevier Ltd. Adoi:10.1016/j.chemosphere.2009.08.048

* Corresponding author. Tel.: +972 48515202; fax:E-mail address: efrat@ocean.org.il (E. Shoham-Frid

DDT’s, PCBs and heavy metals (HM) were measured in tissues of common bottlenose dolphins, collectedalong the Israeli Mediterranean coast during 2004–2006. RDDT and PCBs concentrations were highest inthe blubber, with a wide concentration range of 0.92–142 and 0.05–7.9 mg kg�1 wet weight, respectively.Blubber PCBs values were an order of magnitude lower than in tissues of this and other delphinid speciesin the Western Mediterranea. We found relatively high DDE/RDDT percentage (85–96%); a common indi-cator of DDT degradation, which fitted the general trend of increase in the last 20 years in the Mediter-ranean Sea, indicating the progressive degradation of the remnant DDT and the absence of new inputs.Concentrations of HM ranged as follows: 0.01–123 mg kg�1 wet weight for Hg, <0.04–1.3 for Cd, 1–30for Cu, 0.3–4 for Mn, 19–517 for Fe, 4.3–68 for Zn and 2.4–48 for Ni. These concentrations were similarto those found in specimens collected during previous years in the region, suggesting stability over timein the HM levels of the basin’s food-web.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Cetaceans, top predators in the marine environment, have a re-duced capacity to metabolize hydrophobic persistent chemicalscompared to birds and land mammals. They accumulate high levelsof these compounds up the food web and are most exposed to theirtoxic effects (Marsili and Focardi, 1997; Tanabe, 2002; Wafo et al.,2005; Borrell and Aguilar, 2007 and references therein). Therefore,cetaceans were suggested as potential bio-indicators for organo-chlorine contamination of the marine environment (Aguilar andBorrell, 2005). Cetaceans also accumulate heavy metals which en-ter the food web naturally, or as a result of marine pollution. Accu-mulation may be correlated with age and sex, and depends on foodsources, the physiological state of the individual and the toxicolog-ical dynamics of the specific metal, consequently, a high variabilityin trace metal concentration exists among cetacea species andmarine habitats (Viale, 1978; Martoja and Berry, 1980; Hondaet al., 1983; Law et al., 1992; Law, 1996; Monaci et al., 1998;Shoham-Frider et al., 2003).

Organochlorine compounds such as polychlorinated biphenyls(PCBs) and DDT are synthetic chemicals which are ubiquitous

ll rights reserved.

+972 48511911.er).

contaminants in the marine environment, since they have beenused extensively in agriculture and industry. Even though DDThas been banned for agricultural use for some time, DDT andDDE, the principal breakdown product of DDT in the aquatic envi-ronment, are still found in fish and water from many water bodies.They are chemically stable, biodegrade slowly and are among themost dangerous pollutants because of their toxicity, stability, longbiological half life and high liposolubility. They biomagnify up thefood web and bioaccumulate over the lifetime of their ingestor(Aguilar, 1984; Marsili and Focardi, 1997; Hernandez et al., 2000;Storelli and Marcotrigiano, 2003; Aguilar and Borrell, 2005; Wafoet al., 2005; Borrell and Aguilar, 2007).

There were increasing reports on diseases and epizootics inmarine mammals globally during the 1980s and the 1990s. Thecausative factors are still unclear, but many researchers believethat toxic contaminants played a role in these events (Simmonds,1991; O’Shea and Aguilar, 2001; Tanabe, 2002). Among them, orga-nochlorine pollutants have been implicated in reproductiveimpairment and suppression of the immune system in marinemammals, both strongly detrimental for the long term sustainabil-ity of populations (Borrell and Aguilar, 2005). Several studies triedto link marine mammal pathology to high tissue levels of heavymetals (Law et al., 1992; Siebert et al., 1999). Although a directinfluence of the latter on health status or on the recent mass

Tabl

e1

Iden

tity

and

deta

ilsof

the

com

mon

bott

leno

sedo

lphi

nsfo

und

alon

gth

eIs

rael

iM

edit

erra

nean

coas

tan

dco

ncen

trat

ions

ofpe

rsis

tent

orga

nic

pollu

tant

s(m

gkg�

1w

etw

eigh

t)in

thei

rva

riou

sti

ssue

s.

D-1

D-2

D-4

D-5

D-6

D-1

0

Sam

plin

gda

te28

.1.0

610

.2.0

627

.3.0

627

.4.0

615

.9.0

52.

10.0

4Se

xU

nkn

own

Fem

ale

Fem

ale

Mal

eFe

mal

eM

ale

Age

(yea

r)0.

10.

52

45

1.5

Len

gth

(cm

)16

519

623

224

027

019

4Lo

cati

onA

shdo

dA

shqe

lon

Nah

ariy

aM

ich

mor

etA

shdo

dJa

ser-

Al-

Zark

aPe

stic

ide

Mu

scle

Live

rB

lubb

erLi

ver

Blu

bber

Kid

ney

Live

rB

lubb

erK

idn

eyM

usc

leLi

ver

Blu

bber

Kid

ney

Mu

scle

Live

rB

lubb

erK

idn

eyp,

p-D

DD

0.00

30.

004

0.12

10.

028

2.05

0.08

10.

019

0.77

4–

0.01

40.

030

0.00

5–

–0.

104

0.50

6–

p,p-

DD

E0.

024

0.04

10.

715

2.35

135

6.99

9.78

11.5

–0.

512

1.10

9.77

––

0.42

87.

63–

p,p-

DD

Tn

dn

d0.

083

nd

4.20

0.05

9n

d1.

07–

nd

nd

0.01

––

?0.

848

–R

DD

T0.

026

0.04

50.

919

2.38

141

7.13

9.80

13.4

–0.

526

1.13

9.79

––

0.53

28.

98–

DD

E/R

DD

T(%

)90

9078

9996

9810

086

–97

9710

0–

–80

85–

PCB

28–

––

––

––

0.00

40.

001

––

–n

d0.

001

nd

0.00

6n

dPC

B52

––

––

––

–0.

163

0.01

2–

––

nd

0.00

13n

d0.

106

0.00

9PC

B10

1–

––

––

––

0.44

10.

033

––

–0.

002

0.00

30.

002

0.27

0.04

9PC

B11

8–

––

––

––

0.20

80.

032

––

–0.

002

0.00

50.

002

0.30

30.

023

PCB

138

––

––

––

–2.

561

0.40

9–

––

0.02

30.

025

0.02

11.

640.

196

PCB

153

––

––

––

–2.

180.

319

––

–0.

018

0.02

10.

017

1.60

0.15

5PC

B18

0–

––

––

––

2.34

0.14

2–

––

0.01

10.

023

0.01

00.

779

0.20

5R

PCB

s–

––

––

––

7.90

0.94

7–

––

0.05

60.

079

0.05

34.

700.

637

622 E. Shoham-Frider et al. / Chemosphere 77 (2009) 621–627

mortality events has not been proven, such contribution shouldnot be dismissed. Generally, the question of whether humanstressors affect the state of health of marine mammals is stilldebated (Ciesielski et al., 2006).

The common bottlenose dolphin Tursiops truncatus, (hence-forth CBD) is primarily a coastal species, but can also be foundin pelagic waters and exploit a wide variety of habitats. Its world-wide distribution and great adaptability to diverse habitats makethis species a good indicator of the quality of inshore marine eco-systems (Culik, 2004). CBD, which is the most abundant cetaceanspecies off the Israeli Mediterranean coast (IMC) (Goffman et al.,2006), is listed under Annex II of the European Habitats Directive,which requires member states to designate special areas of con-servation (SAC) to protect their habitat (Berrow et al., 2002). Morerecently, continuing trends of fragmentation and populationabundance decline moved the IUCN (International Union for theConservation of Nature) to downgrade the status of the Mediter-ranean subpopulation to ‘Vulnerable’ (Bearzi and Fortuna 2006).In Israel, 115 specimens of CBD were stranded and/or caughtalong the IMC, since 1993 with an average (1995–2007) of 6.5specimens per year (unpublished records of Israel Marine Mam-mal Research and Assistance Center; IMMRAC).

Data on tissue pollutant levels in cetaceans from the Levantinebasin of the Mediterranean are rare. Our group reported on heavymetals (HM) concentrations in key-tissues of 17 CBD and 6striped dolphins (Stenella coeruleoalba) (Roditi-Elasar et al.,2003) as well as in two Risso’s dolphins (Grampus griseus) (Sho-ham-Frider et al., 2002), collected along the IMC during 1993–1999. As far as we are aware, no data on persistent organic pollu-tants in cetaceans from this region have ever been published. Inthis paper we report on the concentrations of HM, pesticide resi-dues including DDT and its derivatives, and PCBs in various tis-sues of seven CBD stranded on or caught off the IMC during2004–2007.

2. Materials and methods

2.1. Specimen and tissue collection

The dolphins were found along the IMC from Nahariya in thenorth to Ashqelon in the south (Table 1, Fig. 1). Dolphin D-1was found in an advanced state of decomposition and damageto genital area by shark scavenging precluded sex determination.Although all relevant authorities as well as the public (by beachsign-posts) are alerted to notify IMMRAC’s stranding networkimmediately on encountering a beached animal, weather condi-tions throughout most of the year promote decomposition withina matter of days and excluding decomposed animals from theanalysis would have severely narrowed the database.

Dolphin D-2 was also found beached in an advanced state ofdecomposition, with blood issued from the blow-hole and blub-ber thickness was 18 mm. Dolphin D-3, a mature female(14.5 years, 250 cm length), was found beached in Ashqelon inan early state of decomposition. Blubber thickness was 18 mm,the stomach was empty and it was pregnant with a 12 cm fetus.Dolphin D-4 was found floating in the shallows in a fresh state.Blubber thickness was 14 mm. The very fresh body of dolphinD-5 was handed over by the crew of a trawler. It was caught dur-ing the course of a 3 h drag at a bottom depth of �50 m. No dis-tinct gross or microscopic pathology was revealed on autopsy.The stomach was empty except for four otoliths and a few smallfish bones. Dolphin D-6 was found floating 7 km offshore, over abottom depth of 48 m. It was inflated with gas and showing earlysigns of decay. No external signs of entanglement could be ob-served. Blubber thickness was 10 mm. Autopsy did not reveal

34.6 34.8 35 35.2 35.4

31.6

31.8

32

32.2

32.4

32.6

32.8

33

33.2

MediterraneanSea Nahariya

Jaser-Al-Zarka

Michmoret

Ashdod

Ashqelon

Fig. 1. The locations of the common bottlenose dolphins found along the IsraeliMediterranean coast during this study.

Table 2Comparison of heavy metals (HM) concentrations (mg kg�1 wet weight) in commonbottlenose dolphins found along the Israeli Mediterranean coast during this study andduring the period of 1994–2001 (taken from Roditi-Elasar et al. (2003)).

HM Tissue 1994–2001 This study (N = 7)

N Mean ± SD Mean ± SD

Hg Muscle 17 8.9 ± 12 1.12 ± 1.19Liver 14 97 ± 149 35.6 ± 51.5Kidney 14 8.8 ± 9.3 6.7 ± 7.1

Cd Muscle 17 0.1 ± 0.05 <0.04Liver 14 0.49 ± 0.33 <0.04Kidney 14 0.88 ± 1.7 0.57 ± 0.47

Cu Muscle 17 1.2 ± 0.3 1.1 ± 0.6Liver 14 8.9 ± 5.6 11.4 ± 10.7Kidney 14 3.2 ± 0.93 3.0 ± 0.93

Mn Muscle 16 0.38 ± 0.20 0.29 ± 0.31Liver 14 3.5 ± 1.6 2.3 ± 0.85Kidney 14 0.89 ± 0.62 0.52 ± 0.42

Fe Muscle 17 179 ± 78 139 ± 28Liver 14 352 ± 203 386 ± 89Kidney 14 164 ± 49 139 ± 41

Zn Muscle 17 21 ± 13 20.8 ± 7.1Liver 14 44 ± 30 49.5 ± 15.3Kidney 14 18 ± 4.6 24.9 ± 3.9

Ni Muscle Not determined 8.95 ± 6.87Liver 18.2 ± 17.2Kidney 8.46 ± 4.74

E. Shoham-Frider et al. / Chemosphere 77 (2009) 621–627 623

any gross pathology. Dolphin D-10 was found in fresh state floatingover a bottom depth of 9 m. On autopsy, there were no externalsigns of entanglement, but a stomach full of rather fresh fish(Siganus rivulatus) and bloody froth and liquid in the airways pointto post-entanglement drowning as the cause of death. The rest ofthe autopsy, including histology, seemed normal.

Tissues were either collected on site, in the case of advanceddecomposition, or else, during post mortem examination of ani-mals with a body condition code of 1–2, roughly consistent witha period of no longer than 48 h since death (Kuiken and Garcia-Hartman, 1991).

Blubber from the lateral midsection (below the dorsal fin),epaxial muscle, kidney and liver were sampled and stored wrappedin aluminum foil in glass containers for pesticides analysis and un-wrapped in plastic containers for HM analysis.

Age determination by counting teeth growth layer groups(GLGs) was performed by Pavel E. Gol’din (Department of Zoology,V.I. Vernadsky Taurida National University, Simferopol, Ukraine),following standard methodology of decalcification, microtomyand light microscopy of stained sections (Hohn et al., 1989; Hohn,1990). Sub-annual estimates were ascribed for the following agecategories within the first two GLGs, based on a descriptive scale:(1) Age 0 – No neonatal line in dentine. (2) Age 0.1 – Neonatal linepresent, post-natal dentine poorly formed. (3) Age 0.5(1.5) – Post-natal (second GLG) dentine is well-formed, accessory lines or zones

with different dentine structure are discerned. (4) Age 0.75 – FirstGLG thicker than 0.5, neonatal line clearly missing from apical partof root, due to tooth lengthening by addition of post-natal dentine.

2.2. HM Analysis

Tissue samples (muscle, liver and kidney) for trace metal deter-minations (Hg, Cd, Cu, Zn, Fe, Mn and Ni) were kept frozen at�20 �C until analysis. Wet samples were digested with concen-trated nitric acid in Teflon lined, high pressure decomposition ves-sels as described by Hornung et al. (1989). The solutions wereanalyzed specifically for Cd, Cu, Zn, Mn, Fe and Ni by flame atomicabsorption spectrophotometry on a Varian 220 spectrophotometerequipped with a deuterium-arc background corrector. Hg analyseswere performed by cold vapor atomic fluorescence spectrometry(CVAFS) with a Merlin Millenium system (PS Analytical, UK), afterSnCl2 reduction and purging with high purity argon. Detection lim-its for Cd, Cu, Zn, Fe, Mn, Ni and Hg were 0.04, 0.08, 0.03, 0.2, 0.04,0.13 and 10�6 mg kg�1 wet weight, respectively. Chemical blanksthat were run during the analysis presented no evidence of con-tamination. Quality control and quality assurance of trace metaldeterminations were performed on certified standard referencematerials from the National Institute of Standards and Technology(NIST – Oyster tissue 1566b) and from the National Research Coun-cil of Canada (NRCC- DORM 2 and DOLT 3 – Dogfish muscle and li-ver). The standards were digested and analyzed in the samemanner as the samples, with each analytical run. All standard ref-erence materials gave results within 5% of the certified values.

2.3. Persistent organochlorine pollutants analysis

Persistent organochlorine pollutants analysis included pesticideresidues and PCBs. For pesticide residues, wet samples (about 10 g)were ground with anhydrous sodium sulfate to form a dry powder.The powder was shaken on a Gyro-Rotor rotary shaker for about1 h with 100 ml hexane. The hexane was decanted off and the res-idue re-extracted with a second aliquot of hexane. Both organic

624 E. Shoham-Frider et al. / Chemosphere 77 (2009) 621–627

phases were combined, dried over anhydrous sodium sulfate andreduced in volume on a rotary evaporator. The concentrated ex-tract was then cleaned up from interfering substances by chroma-tography on a short column of Florisil, capped with a small amountof anhydrous sodium sulfate. Pesticide residues were eluted with100 ml of 6% (v/v) and 15% (v/v) of diethyl ether in petroleumether, and both fractions dried over anhydrous sodium sulfateand reduced in volume on a rotary evaporator. Finally, the sampleswere dissolved in two portions (1 ml) of hexane, made up to 2 mlwith hexane and transferred to screw capped vial. These sampleswere stored at �20 �C until analyzed. Detection and quantificationof pesticide residues in the extracts were determined by GC–MS(Wynne, 1986, 1991) against the mass spectra and retention timesof a standard mixture containing 44 pesticide residues and break-down products. PCBs were analyzed by a commercial laboratorywith in-house method based on the Pesticide Analytical Manual(FDA, 1994). Shortly, after drying with anhydrous sodium sulfate,the weighed tissue samples were blended with a mixture of1.4:1 ratio of acetonitrile (ACN) and petroleum ether (PE), respec-tively. The ACN phase was separated, cleaned-up and re-extractedwith ACN. Finally, the PCBs were analyzed by GC–MS. Statisticalanalyses were performed under the assumption of 95% confidencelevel.

All results will be given in mg kg�1 wet weight (wwt.). For thesake of convenience, the concentrations will be given without not-ing (wwt.) in the text.

Liver

0

50100

150200

250300

350

0 5 10 15 20 25Age (Y)

Hg

(mg

kg-1

)

1994-2001 This study

Kidney

0

10

20

30

40

0 5 10 15 20 25Age (Y)

Hg

(mg

kg-1

)

1994-2001 This study

Muscle

0

10

20

30

40

0 5 10 15 20 25Age (Y)

Hg

(mg

kg-1

)

1994-2001 This study

Fig. 2. Relations between concentrations of selected heavy metals and age (year) in varcoast during the years 1994–2001 (from Roditi-Elasar et al. (2003) – blue diamonds) anfigure legend, the reader is referred to the web version of this article.)

3. Results and discussion

3.1. Heavy metals

Concentrations of HM in the muscle, liver and kidney of the dol-phins from this study and previous results of the same species andtissues from the IMC are presented in Table 2. Concentrations ofmercury were in the range of 0.009–123 mg kg�1, with a clear pat-tern of organ accumulation: lowest Hg concentrations in the mus-cle, followed by kidney, and highest concentrations in the liver,which is known to be the most important accumulator of mercuryin dolphins (Wagemann and Muir, 1984; Andre et al., 1990; Marco-vecchio et al., 1990; Thompson, 1990; Augier et al., 1993).

Discussion of Hg concentrations must take into account the ageof the specimen, since it accumulates during its life. Comparing themean age-normalized Hg concentrations in the muscle, liver andkidney of dolphins from this study and from the period 1994–2001 (Roditi-Elasar et al., 2003) reveals no differences (Fig. 2).The threshold of tolerance for Hg in mammalian hepatic tissue,above which hepatic damage can occur, seems to be within therange of 100–400 mg kg�1 wet weight. (Wageman and Muir,1984). Hg concentrations measured in this study were much lowerthan this range, except specimen #D-6, which had a concentrationof 123 mg kg�1 in its liver. However, this specimen did not demon-strate any gross pathology in the autopsy, in line with the knownability of marine mammals to immobilize Hg as the selenide and

Liver

0

2

4

6

8

10

0 5 10 15 20 25Age (Y)

Mn

(mg

kg-1

)

1994-2001 This study

Kidney

0

0.5

1

1.5

2

0 5 10 15 20 25Age (Y)

Cd

(mg

kg-1

)

1994-2001 This study

Liver

0

5

10

15

20

25

30

0 5 10 15 20 25Age (Y)

Cu

(mg

kg-1

)

1994-2001 This study

ious tissues of common bottlenose dolphins found along the Israeli Mediterraneand this study (white squares). (For interpretation of the references to colour in this

E. Shoham-Frider et al. / Chemosphere 77 (2009) 621–627 625

accumulate it without apparent harm (Martoja and Berry, 1980;Law, 1996).

Cadmium was detected in the kidney samples, where it was inthe range of 0.5–1.11 mg kg�1. The kidney is considered the mainorgan accumulating Cd (Thompson, 1990). In the other tissues,Cd concentrations were usually lower than 0.04 mg kg�1. It seemsthat the essential elements; Zn, Cu, Fe and Mn also accumulate inthe liver, but their absolute concentrations in all samples werefound to be on the lower side of the concentration ranges of adultmarine mammals (Law, 1996).

Comparison of Cd, Cu, Mn, Fe and Zn concentrations show thatthe recent results are within the range of two standard deviationsof the previous results, i.e. there is no change in the HM concentra-tions over the last few years, regarding this species. Differences ofage-normalized HM concentrations between the period of 1994–2001 and this study were not significant as well (Fig. 2).

Nickel was not measured in the past in tissues of dolphins col-lected in Israel, and only few studies of marine mammals report Niconcentrations (Law, 1996). In this study no clear pattern of accu-mulation in relation to tissue was observed. In mammals generally,dietary nickel is poorly absorbed and relatively nontoxic (Law,1996), but we found an order of magnitude higher range of Ni con-centrations (2.36–47.8 mg kg�1) than the reported range of 0.05–0.49 mg kg�1 in striped dolphins sampled between 1977 and1980 in Japan (Law, 1996).

3.2. Persistent organochlorine pollutants

Unfortunately we could only analyze a few representative sam-ples for PCBs (Table 1). Concentrations of RPCBs in the blubber, thetissue showing the highest values are an order of magnitude lowerthan those found in CBD and other species in the more westernbasins of the Mediterranean Sea (Table 3), possibly attesting to a

Table 3DDT and PCBs (mg kg�1 wet weight) in blubber of different species of dolphins from thetruncatus, S.c = Stenella coeruleoalba, D.d = Delphinus delphis). The reported values were con

Area Species Period N R

Cardigan Bay-West Wales T.t 1988 1 11 11 1

S.c 1 41 5

South China Sea T.t 1994 1 31994 1 71995 1 1

Southeast India T.t 1997–1999 4 1Italy T.t 1987–1992 8 6Italy T.t 1999–2000 9Ireland, Shannon estuary T.t 2000 8 2Greece S.c 1991–1992 1 1Southwestern Mediterranean (Alboran sea) D.d 1992–1994 26 2

S.c 27 5Western Mediterranean (between Spain

and Balearic Islands)S.c 1987 31 1

1988 46 81989 10 61991 17 81992 6 21993 34 42000 6 12001 31 22002 5 3

France S.c 2000–2003 3 3Israel T.t 2004 1 8

2005 1 92006 1 1

1 11 0

a A factor of 30% dry matter content was used according to Law (1996), when such d

lower rate of industrial waste input. In contrast to France and Italywhere PCBs were higher than RDDT concentrations, in our studyconcentrations of RDDT were twice the RPCBs concentrations.

Fifteen different pesticides other than DDT’s were detected inthe various tissues with concentrations between 0.02 and0.67 mg kg�1. No clear pattern of occurrence could be detected,neither in respect to tissue nor with age. Pesticides found in thedolphin’s tissues included insecticides and their metabolites (amit-raz, diazinon, dibrom, dichlorvos, a- and b-endosulfan, endrin,monocrotophos, permethrin, methoxychlor, diphenylamine, hep-tachlor epoxide); fungicides (dinocap), isomeric compounds (b-BHC, an isomer of lindane, c-BHC) and herbicides (prometryn,simazine, simetryn, trifluralin). Most of the insecticides are organo-chlorine compounds and could be considered ‘‘persistant organicpollutants (POPs)”, i.e. they remain in the environment for a longtime, which probably explains why they were detected in thisstudy.

As expected, RDDT concentrations were highest in the blubber(followed by the kidney and liver) with a wide concentration rangeof 0.027–141 mg kg�1. Organochlorines are highly lipophilic andtherefore concentrate in fatty tissues (O’shea and Aguilar, 2001),mainly the blubber tissue, which has a lipid content of 60–90%(Colborn and Smolen, 1996).

General biological traits of the individual, particularly age,nutritive condition and sex are known factors affecting the blubbertissue levels of organochlorine compounds (Aguilar and Borrell,2005). It is known that organochlorine levels increase in males dur-ing their life and concentrations are higher in mature males than infemales, since females lose up to 90% of their total body burden ofthese substances during each pregnancy and lactation (Tanabeet al., 1994; Borrel et al., 1995; Marsili and Focardi, 1997). In thisstudy, in spite of the wide range of concentrations no correlationwas found between RDDT concentrations and age, neither in the

Mediterranean Sea and other regions of the world. (nd-not detected, T.t = Tursiopsverted to wet weight basis, based on data appearing in the cited references.

DDT DDE/RDDT RPCBs References

45 0.41 310 Morris et al. (1989)34 0.32 24071 0.36 3207 0.23 201 0.25 23.87 0.87 1.76 Parsons and Chan (2001)5.6 0.77 24.69.2 0.67 6.092.93 0.72 0.58 Karuppiah et al. (2005).03 0.67 21.7 Marsili and Focardi (1997)

32.71 Storelli and Marcotrigiano (2003).45 3.9 Berrow et al. (2002)5.4 0.77 Georgakopoulou-Gregoriadou et al. (1995)0.5 0.75 19.8 Borrell and Aguilar (2005)2.1 0.74 44.911 0.65 191 Aguilar and Borrell (2005)8.8 0.61 1887.5 0.67 1391.8 0.69 1036.6 0.62 58.56.1 0.74 60.75.5 0.83 25.02.2 0.8 29.91.4 0.83 43.3.52 0.72 61.0 Wafo et al. (2005)a

.98 0.85 4.7 This study

.78 1 –41.4 0.96 –3.4 0.86 7.9.92 0.78 –

ata was unavailable).

626 E. Shoham-Frider et al. / Chemosphere 77 (2009) 621–627

liver nor in the blubber. Among the females in this study, the high-est concentrations were observed in the blubber of dolphin #D-4, a2-years old immature female, which was found in a fresh state. Hgconcentration in the liver of this female was exceptionally high aswell (42.8 mg kg�1). The two other females that underwent org-ano-chlorine analysis were found in a decomposed state and anyattempt at connecting their concentrations to age or reproductivestatus could be confounded by this fact (see below). The twomales; #D-5, 4-years old and #D-10, 1.5 years old, both found ina fresh state had RDDT blubber concentrations of 13.4 and0.9 mg kg�1, respectively, as expected according to increasing con-centrations with age. The bodies of some of the animals assayed inthis study were found in various stages of decomposition, a factthat could bias the results of the organic pollutants, mainly inthe blubber. Serial sampling of blubber (and muscle) from a bea-ched carcass over a period of 65 days, revealed a progressive de-cline in blubber concentrations of RDDT and RPCB, to roughly40% of initial values (Borrell and Aguilar, 1990). When expressedon an extractable lipid basis, the reason is believed to be lossthrough volatilization of the pollutants. When expressed on awet weight basis, tissue loss of fat content due to leaching maybe added (ibid.). We took some measures to reduce environmentaleffects, such as sampling blubber from the unexposed flank of thecarcass, but must acknowledge the probability that some of our re-ported POP values, particularly in the blubber, underestimate thevalues at the time of death. However, the animal with the excep-tionally high RDDT (#D-4) was found in a fresh state, as werethe two animals (#D-5 and #D-10) for which we reported blubberconcentrations. Moreover, the DDE/RDDT ratios were the same inthose animals although it is known that the ratio increases moder-ately as decomposition progresses (Borrell and Aguilar (1990).

RDDT concentrations in the blubber of specimens from thisstudy were generally lower than those from this and other speciesin other areas of the Mediterranean and the world at large (Table3), excluding dolphin #D-4 which had very high RDDT concentra-tions. Actually, this and only three more CBD from Wales hadRDDT higher than 100 mg kg�1 in their blubber in published stud-ies that we were able to collate. Such values were also found in apopulation of striped dolphins off the Spanish Mediterranean coastin 1987, but that population has shown a steady decline in tissueburden, down to a fifth of that value in 2000–2002 (Aguilar andBorrell, 2005).

DDE was the dominant derivative of DDT in all samples ana-lyzed in this study: DDE/RDDT ratios of 0.78–1 (median 0.90, Table2). DDE is the abundant chemical species in biological samples,since it is the product of the chief metabolic pathway of the bio-

y = 0.0124x - 23.986

R2 = 0.6539

0

0.2

0.4

0.6

0.8

1

1.2

1975 1980 1985 1990 1995 2000 2005 2010

Year

DD

E/D

DT

Fig. 3. Time trend of the ratio DDE/RDDT in the blubber of different species ofdolphins from the Mediterranean Sea, sampled between the years 1978–2006(based on data presented in Table 3 and in Borrell and Aguilar (2007) – blackdiamonds) and in common bottlenose dolphins (this study – white squares).

degradation of DDT (Aguilar, 1984) and has a low water solubilityfactor and high persistence in the lipid phase of tissues. Since it isdifficult to degrade or excrete, it is considered to be accumulative.It is known that most biotransformation processes of DDT in verte-brates end up as DDE. Thus, the progressive degradation of theremnant organochlorine load and the absence of new inputs inthe Western Mediterranean since the use of DDT was banned,are further demonstrated by the increase in the relative abundanceof DDE within the DDT mixture. Thus, the DDE percentage, a com-mon indicator of DDT degradation, and therefore of the ‘‘age” of thecontaminant input, increased significantly from about 65% in 1987to 82% in 2002 (Aguilar and Borrell, 2005). We found in this studyrelatively high percentage (78–100%) in 2004–2006, which fits thegeneral trend of increase in the last 20 years in the MediterraneanSea. Plotting DDE/RDDT ratios in the blubber of dolphins from theMediterranean Sea, vs. time (Fig. 3) the increasing trend is clearlyshown. That raises the possibility that the process of DDT agingalong the food web is getting near its end and that no significantnew DDT is reaching the Mediterranean Sea, at least in its easternpart. More data is needed to support this hypothesis.

Acknowledgements

Thanks to all IMMRAC volunteers who helped with the collec-tion of samples. The thorough comments of two anonymousreviewers helped improve the manuscript and are greatlyappreciated.

References

Aguilar, A., 1984. Relationship of DDE/RDDT in marine mammals to the chronologyof DDT input into the ecosystem. Can. J. Fish. Aquat. Sci. 41, 840–844.

Aguilar, A., Borrell, A., 2005. DDT and PCB reduction in the western Mediterraneanfrom 1987 to 2002, as shown by levels in striped dolphins (Stenellacoeruleoalba). Mar. Environ. Res. 59, 391–404.

Andre, J.M., Ribeyre, F., Boudou, A., 1990. Mercury contamination levels anddistribution in tissues and organs of delphinids (Stenella attenuata) from theEastern Tropical Pacific, in relation to biological and ecological factors. Mar.Environ. Res. 30, 43–72.

Augier, H., Park, W.K., Ronneau, C., 1993. Mercury contamination of the stripeddolphin Stenella coeruleoalba Meyen from the French Mediterranean coasts.Mar. Pollut. Bull. 26, 306–311.

Bearzi, G., Fortuna, C.M., 2006. Common bottlenose dolphin Tursiops truncatus(Mediterranean subpopulation). In: Reeves, R.R., Notarbartolo di Sciara, G.(Eds.), The Status and Distribution of Cetaceans in the Black Sea andMediterranean Sea. IUCN Centre for Mediterranean Cooperation, Malaga,Spain, pp. 64–73.

Berrow, S.D., McHugh, B., Glynn, D., McGovern, E., Parsons, K.M., Baird, R.W.,Hooker, S.K., 2002. Organochlorine concentrations in resident bottlenosedolphins (Tursiops truncatus) in the Shannon estuary, Ireland. Mar. Pollut.Bull. 44, 1296–1313.

Borrell, A., Aguilar, A., 1990. Loss of organochlorine compounds in the tissues of adecomposing stranded dolphin. Bull. Environ. Contam. Toxicol. 45, 46–53.

Borrell, A., Aguilar, A., 2005. Differences in DDT and PCB residues between commonand striped dolphins from the southwestern Mediterranean. Arch. Environ.Contam. Toxicol. 48, 501–508.

Borrell, A., Aguilar, A., 2007. Organochlorine concentrations declined during 1987–2002 in western Mediterranean bottlenose dolphins, a coastal top predator.Chemosphere 66, 347–352.

Borrell, A., Bloch, D., Desportes, G., 1995. Age trends and reproductive transfer oforganochlorine compounds in long-finned pilot whales from the Faroe Islands.Environ. Pollut. 88, 283–292.

Ciesielski, T., Szefer, P., Bertenyi, Zs., Kuklik, I., Skora, K., Namiesnik, J., Fodor, P.,2006. Interspecific distribution and co-associations of chemical elements in theliver tissue of marine mammals from the Polish economical exclusive zone,Baltic Sea. Environ. Int. 32, 524–532.

Colborn, T., Smolen, M.J., 1996. Epidemiological analysis of persistentorganochlorine contaminants in cetaceans. Rev. Environ. Contam. T. 146, 92–157.

Culik, M.B., 2004. Review of small cetaceans. Distribution, behavior, migration andthreats. Marine Mammal Action Plan/Regional Seas Reports and Studies no. 177.UNEP/CMS Secretariat, Bonn, Germany. pp. 343.

FDA, Pesticide Analytical Manual, vol. I, third ed., 1994.Georgakopoulou-Gregoriadou, E., Psyllidou-Giouranovits, R., Voutsinou-Taliadouri,

F., Catsiki, V.A., 1995. Organochlorine residues in marine mammals from theGreek waters. Fresenius Environ. Bull. 4, 375–380.

E. Shoham-Frider et al. / Chemosphere 77 (2009) 621–627 627

Goffman, O., Granit, S.L., Hadar, N., Kerem, D., Podiadis, V., Kent, R., Ratner, E., Roditi-Elasar, M., Scheinin, A., Spanier, E., 2006. Cetacean species in IsraeliMediterranean waters: update 2000–2006. In: 3rd Annual Meeting of theIsraeli Association for Aquatic Sciences, May 2006, Haifa, Israel.

Hernández, F., Serrano, R., Roig-Navarro, A.F., Martinez-Bravo, Y., López, F.J., 2000.Persistent organochlorines and organophosphorus compounds and heavyelements in common whale (Balaenoptera physalus) from the westernMediterranean Sea. Mar. Pollut. Bull. 40, 426–433.

Hohn, A.A., 1990. Reading between the lines: analysis of age estimation in dolphins.In: Leatherwood, S., Reeves, R.R. (Eds.), The Bottlenose Dolphin. Academic Press,New York, pp. 75–586.

Hohn, A.A., Scott, M.D., Wells, R.S., Sweeney, J.S., Irvine, A.B., 1989. Growth layers inteeth from known-age free-ranging bottlenose dolphins. Mar. Mamm. Sci. 5,315–342.

Honda, K., Tatsukava, R., Itano, K., Miyazaki, N., Fujiyama, T., 1983. Heavy metalsconcentration in muscle, liver and kidney tissue of stripped dolphin Stenellacoeruleoalba and their variation with body length, weight, age and sex. Agric.Biol. Chem. 47, 1219–1228.

Hornung, H., Krom, M.D., Cohen, Y., 1989. Trace metal distribution in sediments andbenthic fauna of Haifa Bay, Israel. Estuar. Cost. Shelf S. 29, 43–56.

Karuppiah, S., Subramanian, A., Obbard, J.P., 2005. Organochlorine residues inodontocete species from the southeast coast of India. Chemosphere 60, 891–897.

Kuiken, T., García-Hartmann, M., 1991. Proceedings of the first ECS workshop oncetacean pathology: dissection techniques and tissue sampling. ECS (Ecol CompSer) Newsl 17 (spec issue), 1–35.

Law, R.J., 1996. Metals in marine mammals. In: Beyer, N., Heinz, G., Redmon-Norwood, A.W. (Eds.), Environmental Contaminants in Wildlife: InterpretingTissue Concentrations. Lewis Publishers, Inc., Chelsea, Michigan, pp. 357–376.

Law, R.J., Jones, B.R., Baker, J.R., Kennedy, S., Milne, R., Morris, R.J., 1992. Trace metalsin the livers of marine mammals from the Welsh coast and the Irish Sea. Mar.Pollut. Bull. 24, 296–304.

Marcovecchio, J.E., Moreno, V.J., Bastida, R.O., Gerpe, M.S., Rodriguez, D.H., 1990.Tissue distribution of heavy metals in small cetaceans from the southwesternAtlantic Ocean. Mar. Pollut. Bull. 21, 299–304.

Marsili, L., Focardi, S., 1997. Chlorinated hydrocarbon (HCB, DDTs, and PCBs) levelsin cetaceans stranded along the Italian coasts: an overview. Environ. Monit.Assess. 45, 129–180.

Martoja, R., Berry, J.P., 1980. Identification of tiemannite as a probable product ofdemethylation of mercury by selenium in cetaceans. A complement to thescheme of the biological cycle of mercury. Vie et Milieu 30, 7–10.

Monaci, F., Borrell, A., Leonzio, C., Marsili, L., Calzada, N., 1998. Trace elements instripped dolphins (Stenella coeruleoalba) from the Western Mediterranean.Environ. Pollut. 99, 61–68.

Morris, R.J., Law, R.J., Allchin, C.R., Kelly, C.A., Fileman, C.F., 1989. Metals andorganochlorines in dolphins and porpoises of Cardigan Bay, West Wales. Mar.Pollut. Bull. 20, 512–523.

O’Shea, T.J., Aguilar, A., 2001. Cetacea and Sirenia. In: Shore, R.F., Rattner, B.A. (Eds.),Ecotoxicology of Wild Mammals. John Wiley & Sons Ltd., Chichester, UK, pp.427–496.

Parsons, E.C.M., Chan, H.M., 2001. Organochlorine and trace element contaminationin Bottlenose dolphins (Tursiops truncatus) from the South China Sea. Mar.Pollut. Bull. 42, 9, 780–786.

Roditi-Elasar, M., Kerem, D., Hornung, H., Kress, N., Shoham-Frider, E., Goffman, O.,Spanier, E., 2003. Heavy metal levels in bottlenose and striped dolphins off theMediterranean coast of Israel. Mar. Poll. Bull. 46, 491–521.

Shoham-Frider, E., Amiel, S., Roditi-Elasar, M., Kress, N., 2002. Risso’s dolphin(Grampus griseus) stranding on the coast of Israel (eastern Mediterranean).Autopsy results and trace metal concentrations. Sci. Total Environ. 295, 157–166.

Siebert, U., Joiris, C., Hoolsbeek, L., Benke, H., Failing, K., Frese, K., Petzinger, E., 1999.Potential relation between mercury concentrations and necropsy findings incetaceans from German waters of the North and Baltic Seas. Mar. Pollut. Bull.38, 4, 285–295.

Simmonds, M.P., 1991. Cetacean mass mortalities and their potential relationshipwith pollution. In: Symposium Whales: Biology-Threats-Conservation. Brussels,5–7 June.

Storelli, M.M., Marcotrigiano, G.O., 2003. Levels and congener pattern ofpolychlorinated biphenyls in the blubber of the Mediterranean bottlenosedolphins Tursiops truncatus. Environ. Int. 28, 559–565.

Tanabe, S., 2002. Contamination and toxic effects of persistent endocrine disruptersin marine mammals and birds. Mar. Pollut. Bull. 45, 69–77.

Tanabe, S., Iwata, H., Tatsukawa, R., 1994. Global contamination by persistentorganochlorines and their ecotoxicological impact on marine mammals. Sci.Total Environ. 154, 163–177.

Thompson, D.R., 1990. Metal levels in marine vertebrates. In: Heavy Metals in theMarine Environment. CRC Press, Inc., Florida, USA, pp. 43–182.

Viale, D., 1978. Evidence of metal pollution in cetacea of the WesternMediterranean. Ann. Inst. Oceanogr. Paris 54, 5–16.

Wafo, E., Sarazin, L., Diana, C., Dhermain, F., Schembri, T., Lagadec, V., Pecchia, M.,Rebouillon, P., 2005. Accumulation and distribution of organochlorines (PCBsand DDTs) in various organs of Stenella coeruleoalba and a Tursiops truncatus fromMediterranean littoral environment (France). Sci. Total Environ. 348, 115–127.

Wageman, R., Muir, D.C.G., 1984. Concentrations of heavy metals andorganochlorines in marine mammals of northern waters: overview andevaluation. In: Canadian Technical Report on Fisheries and Aquatic Science,1279, 97pp.

Wynne, D., 1986. The potential impact of pesticides on the Kinneret and itswatershed, over the period 1980–1984. Env. Poll. Ser. A. 42, 373–386.

Wynne, D., 1991. Pesticides in the Lake Kinneret (Israel) ecosystem: presentfindings and future prospects. Pesticides in the next decade: the challengesahead. In: Weigmann, D.A. (Ed.), Proceedings of 3rd International PesticideResearch Conference. Virginia Water Resources Research Center, VirginiaPolytechnic Institute & State University, Blacksburg, Virginia, pp. 416–428.