Toxaphene in minke whales (Balaenoptera acutorostrata) from the North Atlantic

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Environmental Pollution 153 (2008) 71e83 www.elsevier.com/locate/envpol

Toxaphene in minke whales (Balaenoptera acutorostrata) from the North Atlantic B. Gouteux a, D.C.G. Muir a,*, S. Backus a, E.W. Born b, R. Dietz c, T. Haug d, T. Metcalfe e, C. Metcalfe e, N. Øien f a

Aquatic Ecosystem Protection Research Division, Environment Canada, Burlington, ON, Canada L7R 4A6 b Greenland Institute of Natural Resources, P.O. Box 570, DK-3900 Nuuk, Greenland c National Environmental Research Institute, Department of Arctic Environment, Frederiksborgvej 399, P.O. Box 358, DK-4000 Roskilde, Denmark d Institute of Marine Research, P.O. Box 6404, N-9294 Tromsø, Norway e Worsfold Water Quality Centre, Trent University, Peterborough, ON, Canada K9J 7B8 f Institute of Marine Research, P.O. Box 1870, N-5817 Bergen, Norway Received 31 July 2006; received in revised form 28 July 2007; accepted 31 July 2007

High levels of toxaphene were found in different sub-populations of minke whales from North Atlantic waters. Abstract Toxaphene contamination of minke whales (Balaenoptera acutorostrata) from North Atlantic waters was examined for the first time. Total toxaphene and SCHB (sum of 11 chlorobornanes) concentrations in blubber samples ranged from 170  110 and 41  39 ng/g lipid weight (l.w.) for female minke whales from southeastern Greenland to 5800  4100 and 1100  780 ng/g l.w. for males from the North Sea, respectively. Very large variations in toxaphene concentrations among sampling areas were observed suggesting a spatial segregation of minke whales. However, much of the apparent geographical discrimination was explained by the seasonal fluctuation of animal fat mass. Patterns of CHBs in males revealed that recalcitrant CHBs were in higher proportions in animals from the more easterly areas than in animals from the more westerly areas. This trend may be influenced by the predominance of the US, over the European, input of toxaphene to North Atlantic waters. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Marine mammals; Organochlorine pesticides; Chlorobornanes; Levels; Patterns

1. Introduction Toxaphene is a complex mixture composed of at least more than 1000 of chlorinated organic compounds (Koryta´r et al., 2003), that was widely used as an insecticide until the mid-1980s in the United States and until the early 1990s in the former Soviet Union and eastern European countries (Saleh, 1991; Voldner and Li, 1993; Li, 2001). It is now banned globally under the Stockholm POPs convention (UNEP, 2001). Because of its considerable use in the past and its intrinsic characteristics of persistence, * Corresponding author. Tel.: þ1 905 319 6921; fax: þ1 905 336 6430. E-mail address: [email protected] (D.C.G. Muir). 0269-7491/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2007.07.031

bioaccumulation potential, and susceptibility to long-range transport, toxaphene is now a global contaminant found worldwide in biota, and particularly in marine mammals such as whales. Baleen whales are relatively long-lived animals, with a large sub-cutaneous fat layer, which have been shown to bioaccumulate large amounts of fat-soluble organochlorine (OC) contaminants. Several studies have described the contamination of North Atlantic minke whales (Balaenoptera acutorostrata) by polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT)-related compounds, and most of the major OC pesticides (Gauthier et al., 1997; Kleivane and Skaare, 1998; Hobbs et al., 2003a). However, none of these studies have reported toxaphene levels, although this pesticide is usually a predominant OC

B. Gouteux et al. / Environmental Pollution 153 (2008) 71e83

72

contaminant in marine mammals (Muir et al., 2000; Wolkers et al., 2000; Braune et al., 2005; Andersen et al., 2006). Minke whales in North Atlantic waters feed almost exclusively during the summer in a wide range of feeding grounds, extending from the east coast of Canada to the east part of the Barents Sea (Horwood, 1990). The International Whaling Commission (IWC) subdivided this summer range of North Atlantic minke whales into 10 management areas referred to as ‘‘IWC small areas’’ (Donovan, 1991). In 1998, blubber samples were obtained from about 150 minke whales from seven of these ‘‘IWC small areas’’ (Fig. 1) as part of studies examining stock differences in minke whale using a large range of tissues signatures including genetic profiles (Andersen et al., 2003), fatty acid composition (Møller et al., 2003), OCs (Hobbs et al., 2003a), heavy metal and radioactive cesium burdens (Born et al., 2002, 2003), and a combination of some of these parameters (Born et al., 2003, 2007). The objective of this study was to assess, for the first time, the toxaphene contamination in blubber of minke whales from the North Atlantic waters. In addition, these levels were compared with other major OC levels reported in the same samples and with toxaphene levels reported in other marine mammals inhabiting the same areas. Finally, toxaphene concentrations and patterns were studied in order to determine if regional variations exist in the contamination by toxaphene of North Atlantic minke whales. Most of the previous work on contamination of marine mammals by toxaphene has been reported in terms of ‘‘total’’ toxaphene using a technical toxaphene standard as a reference. In the last decade, some individual chlorobornane (CHB) congeners have been produced and are now available commercially, enabling the quantification of specific toxaphene components. In this study, both quantitative approaches were used to assess the contamination of minke whales from North Atlantic by toxaphene. 2. Material and methods 2.1. Samples Blubber samples from 149 minke whales were collected from whales harvested in the North Atlantic from 7 IWC management units in the North 70°N

Atlantic: west Greenland (WG), southeast Greenland (SEG), Jan Mayen (JM), North Sea (NS), Vestfjorden/Lofoten (V/L), West Svalbard (WS), and Barent Sea (BS) (Fig. 1, Table 1). Blubber samples were taken during Greenland and Norwegian whaling operations, in 1998, by licensed local hunters and trained scientific staff, respectively. Animals were measured for standard body length on board. The sex of animals was also determined in the field and was subsequently confirmed genetically from skin samples (Andersen et al., 2003). Blubber samples were stored at 20  C until their analysis.

2.2. Chemical analysis Blubber samples were extracted and prepared for analysis in the Worsfold Water Quality Centre, at Trent University, as described in Metcalfe and Metcalfe (1997) and outlined in Hobbs et al. (2003a). Briefly, samples were extracted into hexane by Soxhlet extraction and lipids were removed from the extracts by gel permeation chromatography (GPC). The lipid fraction isolated by GPC was evaporated to dryness for gravimetric determination of lipid content. The contaminant fraction isolated by GPC was purified on an activated silica column by eluting with hexane (Fraction 1) and then eluting with 50:50 hexane:dichloromethane (Fraction 2). B8-1413 was collected in Fraction 1, along with PCBs and 4,4’-DDE, and other CHBs were collected in Fraction 2 with the rest of the OC compounds. Each fraction was transferred to iso-octane and concentrated to 1 mL prior to gas chromatographyemass spectrometry analysis. Toxaphene compounds were analyzed using a HewlettePackard Model 6890 gas chromatograph (GC) with an HP5-MS column (30 m  0.25 mm id  0.25 mm film thickness) coupled to a HewlettePackard Model 5973 mass spectrometric (MS) detector operated in electron capture negative ion (ECNI) mode. The GC temperature program was described in Muir et al. (2004). Selected ions m/z 309e311 (Cl-6), 343e345 (Cl-7), 377e379 (Cl-8), and 411e413 (Cl-9) were monitored to identify hexa-, hepta-, octa-, and nonachlorobornanes according to the methods described by Swackhamer et al. (1987) and Glassmeyer et al. (1999), to which slight modifications were made. The quantification of hexa- to nonachlorobornane homologue groups was carried out by comparing GC-ECNIMS chromatograms obtained with a sample to the technical toxaphene standard, using the single response factor procedure (Muir et al., 2004). The total toxaphene concentration was then estimated as the sum of homologue group concentrations. Twenty four individual congeners (e.g. Parlar-11, P-12, P-15, B6-923, B7-499 (P-21), B7-1001, P-25, B7-515 (P-32), B8-1413 (P-26), P-31, B8-789 (P-38), B8-531 (P-39), B8-1414 (P-40), B8-1945 (P-41), B8-809 (P-42), B8-2229 (P-44), B9-1679 (P-50), B8786 (P-51), B9-1046 (P-56), B9-715 (P-58), B9-1049 (P-59), B9-1025 (P-62), B9-2206, B10-1110 (P-69)) were quantified in the same way using authentic external standards of each compound obtained from Dr. Ehrenstorfer GmbH (Germany). P-11 and P-12 along with B8-1414 and B8-1945 were reported as P-11/12 and B8-1414/1945, respectively, since they were not

80°N

Novaya Zemlya Svalbard

50°E

BS

WS

Canada Greenland Jan Mayen

60°N

WG

30°E

VL

JM

Norway

SEG

Iceland

NS

50°W 0

1000 km

UK 30°W

10°E

10°W

Fig. 1. Location of sites of capture for minke whales sampled in the North Atlantic in 1998. Acronyms and boundaries of relevant IWC ‘‘small areas’’ are indicated (see text for details).

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Table 1 Sampling locations and periods, sex, length and number of minke whales sampled, and lipid content of blubber samples collected in 1998 in the North Atlantic Location

Abbreviation

Sampling period

Sex

na

Lipids (%)

Length (cm) b

West Greenland

WG

6 May to 31 October

F M

Mean  SD

Mean  SD

31 5

72  10 71  20

683  125 659  136

Southeast Greenland

SEG

12 July to 16 October

F

4

73  14

795  153

Jan Mayen

JM

7 June to 1 July

F M

19 5

74  8.9 74  6.2

775  55 671  75

North Sea

NS

15 May to 8 June

F M

14 9

66  13 67  14

786  98 755  69

Vestfjorden/Lofoten

V/L

28 May to 14 August

F M

7 7

81  8.1 71  11

719  138 624  163

West Svalbard

WS

15 May to 31 May

F M

15 1

57  12 79

768  43 700

Barents Sea

BS

23 May to 25 June

F M

29 3

67  16 68  4.2

756  60 764  53

a b

n ¼ number of samples. SD ¼ Standard deviation.

chromatographically separated. Toxaphene congeners were referred using either their AV-code ‘‘BX-YYYY’’ (Andrews and Vetter, 1995) or their Parlar number when no AV-code is available (Parlar et al., 1995).

2.3. QA/QC Quality assurance included analysis of procedural blanks, duplicate samples and cod liver oil standard reference material (NIST 1588a; National Institute of Standards and Technology, Gaithersburg, MD). Results for 5 samples analyzed in duplicate indicated that the relative percent differences for total toxaphene averaged 25%. Results for total toxaphene in NIST 1588a (n ¼ 8) averaged 3753  855 ng/g, which is within 6% of the value reported by Kucklick et al. (2004). Results for B8-1413, B9-1679, and B9-1025 deviated by 36%, 29% and 72% of values reported by Kucklick et al. (2004) for these congeners, but were within the range of concentrations reported by Vetter and Oehme (2000) for NIST 1588a. Blank values for all CHBs and total toxaphene were uniformly low indicating that procedural contamination was lower than the sample detection limits. For individual CHBs, sample detection limits varied between 0.003 and 3.3 ng/g wet weight depending on the sample size and the signal-to-noise ratio occurring at the retention time of the target CHB. For total toxaphene, sample detection limits varied between 0.1 and 5.5 ng/g wet weight. Thirteen individual toxaphene congeners, P-11/12, P-15, B6-923, B7-499, B7-1001, P-25, B7-515, B8-786, B9-1046, B9-715, B9-1049, and B10-1110 were only detected occasionally in minke whales (e.g. 20% or less of the samples) and were excluded from the subsequent analysis and discussion. For the other individual toxaphene congeners, concentrations below detection limits were substituted with random values between one-tenth and the detection limit of each compound prior to run any statistical tests. The sum of concentrations of widely detectable toxaphene congeners B8-1413, P-31, B8-789, B8-531, B8-1414, B8-1945, B8-809, B8-2229, B9-1679, B9-1025, and B9-2206 was reported as SCHBs.

2.4. Statistical analysis Toxaphene concentrations were lipid normalized and log10 transformed prior to statistical analyses, but the biological factor ‘‘length’’ was not transformed. All statistical analyses were performed using Systat 11 software (Systat Software Inc., Point Richmond, CA). Spatial trends of toxaphene concentrations in minke whales in North Atlantic were examined by analysis of covariance (ANCOVA) of the form: log10 concentration ¼ m þ sampling area þ length þ sampling area  length þ 3, where m is a constant and 3 is

an error term. ANCOVA was done separately for each sex because female minke whales grow to a longer body length than males. Therefore, the interaction between sex and length could hide the specific influence of these factors. Preliminary tests revealed that, for total toxaphene, SCHBs, and all individual CHBs tested, length and the sampling area  length interaction were not significant for describing trends of toxaphene concentration in minke whales of each sex. Thus, the ANCOVA was successively reduced to a simple analysis of variance (ANOVA) of the form: log10 concentration ¼ m þ sampling area þ 3. A multiple comparison procedure, using Tukey’s post hoc test, was applied to determine which specific ‘‘sampling area’’ differed from the others (Zar, 1984). Principal component analysis (PCA) was used to examine the detectable CHB congener pattern in the minke whales from the different sampling areas. To enhance the interpretation of variables, the factor matrix was rotated with the Varimax method. Prior to PCA analysis, CHB congeners were normalized by dividing concentrations of each analyte by SCHBs and, then, standardized. In all statistical tests, the significance level was set at a ¼ 0.05.

3. Results and discussion 3.1. Sex and age differences Whatever the sampling area, male minke whales were generally more contaminated than female animals. For example, SCHB concentrations ranged from 9 to 930 ng/g lipid weight (l.w.) for female minke whales and from 35 to 2600 ng/g l.w. for male minke whales. Both total toxaphene and SCHB levels were roughly 1.5e3 times higher in males than in females. This is comparable to previously reported results for toxaphene in long-finned pilot whales (Dam and Bloch, 2000) or belugas (Gouteux et al., 2003; Hobbs et al., 2003b). Females can transfer large quantities of lipophilic OCs to their fetus during gestation and to their calves through lactational transfer (Borrell et al., 1995; Debier et al., 2003a; Sørmo et al., 2003; Metcalfe et al., 2004). This reduces the burden of contaminants in females in contrast to that in males. No age determinations were made on the 149 minke whales (121 females, 28 males) but their sexual maturity was assessed

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based on measurements of standard body length. Eighteen males and 79 females with a length superior to 670 cm and 730 cm, respectively, were judged sexually mature, as described by Hobbs et al. (2003a). Thirty-nine females and 10 males likely had not yet reached sexual maturity. Finally, the length of three whales was not recorded. Owing to the fact that age is an important parameter that is often related to OC concentrations in marine mammals, the contamination of minke whales by toxaphene was studied as a function of the maturity of the animals. No distinct patterns of contamination were observed between immature and mature animals. Moreover, no correlations between total toxaphene or CHB levels and age, expressed using standard body length, were found. 3.2. Total toxaphene versus SCHBs As illustrated in Table 2, mean concentrations of SCHBs accounted on average for only 20  8% of total toxaphene in blubber of minke whales sampled. This is in the range of the contributions of specific CHBs to total toxaphene usually observed in biological samples. For example, in phytoplankton from the Lake Superior, available major CHBs (B8-1413, B8-189, B8-1414/1945, B8-809, B8-2229, B9-1679, and B9-1025) accounted for only 5% of total toxaphene, while, in belugas from the St. Lawrence, only two available CHBs (B8-1413 and B9-1679) accounted for about 50e65% of total toxaphene (Muir et al., 1996, 2004). This large difference reflects several aspects of the challenging analysis of toxaphene in environmental samples. On one hand, total toxaphene was quantified using a single factor procedure, where homologue group responses from a technical toxaphene calibrant are summed and a response factor is determined relative to an internal standard. This approach suffers from some drawbacks including, among others, potential interferences from co-eluting compounds and important differences between the altered toxaphene profile observed in environmental samples compared to the original pattern of the technical standard (Bidleman et al., 2004; Kucklick and Helm, 2006). These limitations may lead to a biased result such as an overestimation of the total toxaphene concentration in our samples. Nevertheless, this approach is still useful since much of the toxaphene residue data in the literature is for total toxaphene as noted in Table 3. On the other hand, specific CHBs were quantified using individual toxaphene congener standards allowing a much better reliability of the analysis. However, this approach also suffers from some limitations since far fewer CHBs are available as standards than the number likely to occur as environmental residues (de Geus et al., 1999; Vetter and Oehme, 2000; Kucklick and Helm, 2006). 3.3. Comparison with other OCs Concentrations of several OCs (PCBs, DDTs, CHLs, HCHs, HCB, dieldrin, endrin, mirex, a-endosulfan, and lindane) in the same minke whale samples were reported earlier

by Hobbs et al. (2003a). Comparisons to these OC levels revealed that total toxaphene was generally one of the three predominant OC classes with SPCB and SDDT in both male and female minke whales. For instance, mean concentrations of total toxaphene were similar to SPCB (sum of 102 congener peaks) concentrations and higher by a factor of about 2e3 than mean concentrations of SDDT (sum of o, p and p, p’-DDE, -DDD, -DDT) in whales sampled from JM, NS, and WS sampling areas. For whales from the WG and BS sampling areas, total toxaphene concentrations were about 2e3 times lower than SPCB concentrations and similar to SDDT concentrations. For whales from these sampling areas, the fourth most important OC class was SCHL (sum of cis- and trans-chlordane, oxychlordane, cis- and trans-nonachlor, heptachlor, heptachlor epoxide, and methoxychlor), which had concentrations that were up to about one order of magnitude lower than total toxaphene concentrations. This ranking of predominant OC compounds is consistent with the OC patterns observed in Arctic marine mammals such as belugas from Svalbard, Greenland, or from the Canadian Arctic (Braune et al., 2005; Andersen et al., 2006), harp seals from the Barents Sea (Wolkers et al., 2000), or Greenland walrus (Muir et al., 2000). This supports the fact that toxaphene, one of the less documented OC pesticides in marine mammals, is still a predominant pollutant that must be considered in the health assessment of marine mammal populations. 3.4. Comparison with other marine mammals This study represents the first attempt to assess the contamination of minke whales by toxaphene. Hence, toxaphene levels in minke whales were only comparable with those reported for other marine mammals inhabiting similar parts of the North Atlantic. This comparison is influenced by differences in several biological factors that affect the animals, such as sex, age, nutritive condition, metabolic capacity and diet (Aguilar et al., 1999; Krahn et al., 2003) and also from methodological factors related to the sampling and analytical methods, the choice of individual congeners reported, and the statistical treatment of the data (Andersen et al., 2001; Krahn et al., 2003). Considering these limitations, only general comparisons are possible. Minke whales from a specific North Atlantic region tended to be generally more contaminated than pinnipeds such as seals or walrus inhabiting the same area (Table 3). This difference may be partly attributed to a lower metabolic capacity for degradation of xenobiotics for cetaceans compared to pinnipeds (Tanabe et al., 1988; Boon et al., 1997; Houde et al., 2005). For toxaphene, in vitro studies have demonstrated that B9-1025 was partly metabolized by hepatic microsomes of harbor seals (Phoca vitulina) and gray seals (Halichoerus grypus), but not by hepatic microsomes of cetaceans such as harbor porpoise (Phocoena phocoena), whitebeaked dolphin (Lagenorhynchus albirostris), and sperm whale (Physeter macrocephalus) (Boon et al., 1998, 2001; van Hezik et al., 2001). Furthermore, Gouteux et al. (2005) have shown, by evaluating the accumulation of CHBs in seals relative to their diet, the

Table 2 Summary of toxaphene concentrations (ng/g l.w.) in the blubber of minke whales sampled in the North Atlantic in 1998 Area

Sex

n

B8-1413

P31

B8-789

B8-531

B8-1414/1945

B8-809

B8-2229

B9-1679

B9-1025

B9-2206

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

Mean  SD (Range)

780  1000 (12e3800) 1100  860 (250e2100)

150  210 (9e740) 220  200 (43e430)

6.0  8.8 (1.2e43) 7.1  6.8 (2.1e19)

1.9  2.8 (NDbe11) 3.1  2.6 (0.9e6.9)

22  30 (1.9e110) 35  36 (7.2e89)

0.8  1.3 (NDe5.0) 1.5  1.4 (0.3e3.2)

14  19 (0.7e67) 20  19 (3.6e47)

4.6  6.2 (0.3e21) 6.9  6.2 (1.5e16)

36  51 (1.4e200) 54  50 (11e120)

48  72 (1.6e320) 61  53 (8.7e130)

19  28 (1.0e120) 29  27 (6.5e64)

0.5  0.7 (NDe2.8) 0.7  0.6 (0.2e1.5)

a

WG

F

31

M

5

SEG

F

4

170  110 (64e320)

41  39 (13e98)

2.0  0.6 (1.3e2.7)

1.0  1.3 (NDe2.9)

12  14 (2.6e33)

0.4  0.5 (0.1e1.2)

4.0  4.0 (1.1e9.9)

2.5  3.2 (0.7e7.3)

9.5  8.5 (2.8e22)

6.4  4.6 (2.5e13)

3.4  1.7 (1.4e5.5)

0.2  0.3 (0.1e0.6)

JM

F

19

M

5

2200  1600 (180e4600) 5400  5300 (320e12 000)

420  340 (41e880) 990  950 (59e2200)

28  29 (1.1e79) 59  69 (1.9e160)

5.9  4.7 (0.5e13) 11  11 (NDe23)

56  45 (5.5e130) 100  92 (8.1e190)

2.2  1.7 (0.2e4.9) 3.5  3.2 (0.3e6.7)

31  24 (3.1e66) 75  71 (4.4e150)

19  16 (1.4e49) 24  21 (1.7e48)

84  67 (8.0e180) 200  190 (14e430)

130  100 (11e290) 360  350 (19e830)

66  53 (4.9e150) 150  150 (8.8e360)

1.5  1.2 (0.1e3.5) 3.8  3.6 (0.1e7.9)

F

14

M

9

1900  1400 (290e5300) 5800  4100 (1200e14 000)

350  260 (60e930) 1100  780 (120e2600)

21  17 (5.9e65) 120  150 (1.7e420)

3.3  2.2 (0.4e7.9) 6.1  3.6 (NDe9.7)

34  22 (4.9e79) 78  45 (9.6e150)

0.8  0.6 (NDe1.8) 1.8  1.0 (NDe2.9)

34  26 (5.3e100) 100  74 (14e240)

5.5  3.0 (1.0e12) 9.8  5.2 (1.1e19)

81  61 (11e200) 210  130 (28e430)

130  102 (21e340) 440  130 (28e430)

40  35 (5.0e140) 100  63 (11e210)

0.8  0.7 (0.1e2.3) 1.8  0.9 (0.2e2.9)

F

7

M

7

230  160 (70e530) 400  240 (160e700)

48  36 (16e120) 81  53 (35e150)

7.9  11 (1.1e31) 13  16 (2.0e40)

0.5  0.3 (0.2e0.9) 0.6  0.2 (0.3e0.8)

4.0  2.3 (1.8e8.5) 4.9  2.5 (0.4e8.2)

0.2  0.1 (0.1e0.3) 0.2  0.1 (NDe0.3)

3.7  2.1 (1.8e7.9) 6.2  3.0 (2.9e11)

1.1  0.5 (0.3e1.7) 1.1  0.5 (0.6e2.1)

8.8  5.8 (3.6e21) 13  4.9 (6.4e19)

17  13 (4.7e41) 35  27 (9.8e72)

4.9  2.5 (2.2e8.9) 6.8  3.7 (2.8e12)

0.1  0.1 (NDe0.2) 0.1  0.0 (0.1e0.1)

F

15

M

1

2000  1100 (510e4800) 2100 e

480  220 (190e930) 440

20  9.9 (5.5e35) 18 e

6.6  3.5 (2.2e13) 7 e

68  30 (25e120) 68 e

3.1  1.5 (0.9e5.8) 3 e

48  22 (25e100) 43 e

17  6.7 (6.8e29) 14 e

120  56 (58e260) 100 e

130  65 (32e240) 130 e

62  39 (13e140) 54 e

1.6  0.8 (0.6e3.7) 2 e

F

29

M

3

890  700 (190e2700) 2000  1100 (1100e3200)

210  230 (34e780) 500  480 (140e880)

10  11 (1.1e42) 26  19 (7.7e45)

2.6  2.8 (0.3e8.8) 4.7  3.5 (0.8e7.6)

26  25 (5.0e84) 59  50 (9.3e110)

1.2  1.4 (NDe4.6) 1.9  1.4 (0.3e3.1)

21  24 (3.8e84) 56  49 (12e110)

6.2  6.8 (0.9e23) 6.5  5.1 (1.1e11)

45  47 (7.4e160) 110  82 (22e190)

69  83 (7.3e300) 180  120 (70e310)

29  32 (3.7e110) 52  39 (13e90)

0.6  0.7 (0.1e2.3) 1.3  1.0 (0.2e2.1)

NS

V/L

WS

BS

a b

B. Gouteux et al. / Environmental Pollution 153 (2008) 71e83

SCHBs

Total

SD ¼ Standard deviation. ND ¼ Not detected.

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Table 3 Mean concentrations of SCHBs and total toxaphene (ng/g l.w.) in blubber of marine mammals inhabiting similar regions of the North Atlantic as the minke whales sampled in this study Marine mammal

Pinnipeds Ringed seal

Gray seal Harbor seal Harp seal Walrus

Cetaceans Harbor porpoise Pilot whale

Narwhal White whale

na

Region (corresponding IWC small area)

Sex

Greenland (WG, SEG) Svalbard (WS) Svalbard (WS) Svalbard (WS) Svalbard (WS) Svalbard (WS) Western Iceland (JM) Baltic Sea (NS) Svalbard (WS) North Sea (NS) Barents Sea (BS) Northwest Greenland (WG) Northwest Greenland (WG) East Greenland (SEG)

nab M F M F MþF na na M na MþF M F M

56 5 5 7 7 14 6 1 6 1 13 5 11 8

na 1e17 na Adult Adult Juvenile na na Adult na Juvenile 10 10 18

1994 1993 1992 1996 1996 1996 Before 2001 Before 2001 2000 Before 2001 1997 1988 1988 1989

Northeast Atlantic (JM, NS, V/L) Faroe Islands (NS) Faroe Islands (NS) Faroe Islands (NS) Northwest Greenland (WG) Southwest Greenland (WG) West Greenland (WG) West Greenland (WG) Svalbard (WS)

na M F MþF M M M F M

68 54 193 173 3 50 71 67 10

na 20 22 Juvenile 7 7 5 6 Adult

1997e2001 1997 1997 1997 1993 1993 1989e1990 1989e1990 1995e1997

Age (year)

Period

SCHBs

Total toxaphene

Mean  SD

Mean  SD 307  164c

d

z9 z7d

51  28e 42  28e 28  13e

48 c,f 733c,f 171g 1457c,f 496h 319  39c 314  41c 1610  305c 880i z4300j z2200j z6900j 2376  1497k 1554  1117k

11 447  4208l

5772  2458 4799  2313 3690  1460 3010  1620

Reference

Cleeman et al. (2000) Føreid et al. (2000) Føreid et al. (2000) Wolkers et al. (1998) Wolkers et al. (1998) Wolkers et al. (1998) Vetter et al. (2001) Vetter et al. (2001) Wolkers et al. (2004) Vetter et al. (2001) Wolkers et al. (2000) Muir et al. (2000) Muir et al. (2000) Muir et al. (2000) Thron et al. (2004) Dam and Bloch (2000) Dam and Bloch (2000) Dam and Bloch (2000) Dietz et al. (2004) Dietz et al. (2004) Stern et al. (1994) Stern et al. (1994) Andersen et al. (2006)

a

n ¼ number of samples. na ¼ not available. c Concentration in ng/g wet weight. d Mean SCHBs (B8-1414 þ B9-1679 þ B9-1025) concentrations were estimated based on the Fig. 5 in Foreid et al. (2000). e Total toxaphene was calculated by Wolkers et al. (1998) using a multiplication factor based on the total surface area from all toxaphene congeners relative to B8-1413 and B9-1679. f SCHBs ¼ B7-1453 þ B8-1412 þ B8-1413 þ B8-1414/1945 þ B8-2229 þ B9-1679 þ B9-1025. g Geometric mean, SCHBs ¼ B8-1413 þ B8-1414 þ B8-2229 þ B9-1679. h Total toxaphene was calculated by Wolkers et al. (2000) as 3  B8-1412 þ B9-1679. i Median, SCHBs ¼ B8-1413 þ B8-1414 þ B8-1945 þ B8-809 þ B8-2229 þ B9-1679. j Mean SCHB concentration were estimated as the sum of mean concentrations for B8-1414, B9-1679, and B9-1025 reported in Dam and Bloch (2000). k SCHBs ¼ B8-1413 þ B7-515 þ B9-1679 þ B9-1025. l Mean SCHBs concentration was estimated by Andersen et al. (2006) as the sum of mean concentrations of B8-1414, B9-1679, and B9-1025. b

potential biotransformation of B8-1414/1945 in hooded (Cystophora cristata), harbor, harp (Phoca groenlandica), and gray seals from the eastern Canada. The CHBs (B8-1414/1945, B9-1025) shown to be metabolized by pinnipeds are generally minor constituents compared to those that predominate (e.g. B8-1413, B8-2229, or B9-1679) in most marine mammals. However, for minke whales, the concentrations of known metabolizable CHBs represent a non-negligible part (20e25%) of the SCHB concentrations (Table 2). In general, minke whales were less contaminated than other cetaceans sampled in similar locations (Table 3). This difference may be partly explained by differences in the diet of minke whales and other cetaceans listed in Table 3. The diet may be a good predictor of the contamination of marine mammals by CHBs because some of these compounds persist in the environment and are highly lipophilic, leading to their biomagnification between increasing trophic levels within food

webs (Mackay and Fraser, 2000; Fisk et al., 2001; Hoekstra et al., 2003). Minke whales, which belong to the mysticete suborder (baleen whales), are known to feed on a relatively high proportion of plankton (Horwood, 1990; Haug et al., 2002), while the odontocetes (toothed whales) such as pilot whales, belugas, narwhals (Monodon monoceros), and harbor porpoises (Phocoena phocoena), consume mainly organisms of higher trophic levels such as fish or squid (Gannon et al., 1997; Lesage et al., 2001; Das et al., 2004; Laidre et al., 2004). Consequently, the trophic level of mysticetes should be lower than the odontocetes explaining part of the difference in toxaphene contamination of animals from these two distinct cetacean suborders. In fact, based on published accounts of stomach contents as well as morphological and behavioral information, Pauly et al. (1998) estimated that minke whales have a trophic level of 3.4, well below trophic levels of belugas (4.0), harbor porpoises (4.1), narwhals (4.2), and pilot

B. Gouteux et al. / Environmental Pollution 153 (2008) 71e83

3.5. Toxaphene levels among animals from the same location As shown in Table 2, toxaphene concentrations found among males or females from a specific location varied widely. For example, SCHBs for females from WG varied by about two orders of magnitude from 9 to 740 ng/g l.w. (Table 2). This large variation was also reported for other OCs in the same samples. Hence, SPCB varied from 89.1 to 10 200 ng/g l.w. in the blubber of male minke whales from the WG area (Hobbs et al., 2003a). This could be explained by a vast range in ages of the animals sampled since, in general, OC concentrations were positively related to age in several marine mammal studies (Aguilar et al., 1999; Muir et al., 2000). However, no correlations between contaminant levels and age, expressed using both standard body length and in terms of maturity, were found in the present study. This indicates that the large variations in OC levels are due to other factors, such as particular feeding behavior or body condition of specific animals. 3.6. Geographical variation of toxaphene levels Very large variations in toxaphene concentrations were observed among sampling locations. For example, SCHB concentrations in female minke whales varied by about one order of magnitude from 41  39 ng/g l.w. in the SEG area to 480  220 ng/g l.w. in the WS area (Table 2). For male minke whales, the same level of variation was observed between the lowest and the most contaminated animals, which were from the V/L area (SCHBs ¼ 81  53 ng/g l.w.) and the NS area (SCHBs ¼ 1100  700 ng/g l.w.), respectively (Table 2). Significant differences in toxaphene concentrations were detected between sampling areas (ANOVA; p < 0.0005) for both male and female minke whales. However, the segregation of sampling areas was difficult to assess because the multiple comparison test yielded numerous overlapping sets with similar SCHB concentrations (Fig. 2). For male animals, JM and NS areas could be differentiated from the V/L sampling area according to significantly higher levels of SCHBs in the former regions (Fig. 2). For females, animals at JM, NS, and WS were significantly more contaminated than at SEG, WG, and V/L (Fig. 2). Additionally, mean SCHB levels at WS were significantly higher than at BS. Similar results indicating a lower degree of contamination of minke whales from the WG, SEG, and V/L areas and greater contamination of animals from JM, NS, and WS areas were obtained by testing either data on total toxaphene or data on individual CHBs (data not shown). The International Whaling Commission (IWC) has divided North Atlantic minke whales into four major management

1500

β

Female Male

ΣCHBs (ng/g l.w.)

whales (4.4). This comparison, based on estimates, is partly supported by trophic levels, determined using d15N analyses for animals sampled in this study, which varied slightly from 2.9 for animals from the SEG sampling area to 3.4 for animals from the NS sampling area (Born et al., 2003).

77

β

1000 α,β

c

b,c

500

b,c α,β

a

a,b

α

a

a

SEG

V/L

0 WG

BS

JM

NS

WS

IWC "small areas" Fig. 2. Mean concentrations ( standard error) of SCHBs in minke whales from each IWC ‘‘small areas’’. Female and male minke whales from IWC ‘‘small areas’’ marked with different letters and symbols, respectively, have significantly different levels of SCHBs.

areas or ‘‘stocks’’: Canadian East Coast; West Greenland; Central Atlantic, which includes East Greenland, Iceland and Jan Mayen; and Northeastern Atlantic, which includes Svalbard, Norway, and British Isles (Anonymous, 1994). However, this identification of sub-populations was refined recently following the conclusions of a set of studies based on regional variations in minke whale genetic signatures (Andersen et al., 2003), fatty acid compositions (Møller et al., 2003), organochlorine (Hobbs et al., 2003a), heavy metal and radioactive cesium burdens (Born et al., 2002, 2003), and even the combination of certain of these parameters (Born et al., 2007). It should be mentioned that these studies were conducted using the same animals as in this study. One of the major findings of these studies was that minke whales from the NS area were distinctive from those in the other sub-areas, and in particular other Northeastern Atlantic areas (WS, BS, and V/L) (Andersen et al., 2003; Møller et al., 2003; Born et al., 2002, 2003, 2007). As a result, it was suggested that minke whales from the NS area should be considered as an additional distinctive stock. However, based on the regional variations of levels and relative proportions of the dominant OCs (PCBs, DDT, and chlordane related compounds), animals from the NS area appeared to be similarly contaminated than those in other Northeastern Atlantic areas, including animals from the JM area, which is representative of the Central Atlantic stock (Hobbs et al., 2003a). It was also suggested that, based on organochlorine burdens and fatty acid composition, animals from WG and SEG waters should be considered as one distinctive stock (Hobbs et al., 2003a; Møller et al., 2003). This was contradictory to the results from genetic signatures, which indicated that WG animals were genetically distinctive from the SEG animal stock (Andersen et al., 2003). Not surprisingly, since toxaphene congeners share similar physico-chemical properties with PCBs, DDT, and chlordane related compounds, our results confirmed the observations made by Hobbs et al. (2003a) for whales from the NS area

78

B. Gouteux et al. / Environmental Pollution 153 (2008) 71e83

and the Greenland areas. However, our results showed a feature that was not observed in the previous studies regarding minke whales from the V/L sampling area, as animals of both sexes from this sampling area were clearly less contaminated with toxaphene than those from adjacent Northeastern Atlantic sampling areas. Spatial variations of marine mammal contamination by OCs may reflect differences in the diet of these animals (Hobbs et al., 2002; Hobbs et al., 2003b; Gouteux et al., 2005). Preferential prey of minke whales are thought to be krill and small fish such as herring (Clupea harengus), capelin (Mallotus villosus), mackerel (Scomber scombrus), polar cod (Boreogadus saida), or sand eel (Ammodytes sp.) (Horwood, 1990; Neve, 2000; Sigurjo´nsson et al., 2000; Olsen and Holst, 2001; Haug et al., 2002). Unfortunately, some limitations restrain our ability to discuss adequately of the spatial variability of the toxaphene contamination of these prey species. First, toxaphene data for krill or small fish in North Atlantic waters are too scarce or non- available. Moreover, the highly variable diet regime of minke whales, characterized by opportunistic feeding habits and inter-annual variations of preferential preys, prevents any firm conclusions regarding the diet of animals from a specific area (Horwood, 1990; Haug et al., 2002). In fact, within the geographical range covered by this study, minke whales may be differentiated only by the relative proportions of krill and small fish that they consume. All fish species known as food items of minke whales are considered to be principally planktivores suggesting a relatively similar trophic level. Hence, the main trophic level differences between the prey items of minke whales should be between these fish species and krill; the latter group of crustaceans being about one trophic level lower than fish as supported by d15N measurements in krill (d15N ¼ 8.3  0.8&; Trophic Level ¼ 2.1), capelin (d15N ¼ 12.5  0.9&; TL ¼ 3.2), and remaining fish (d15N ¼ 12.3  1.5&; TL ¼ 3.2) sampled from the stomach contents of WG minke whales (Born et al., 2003). Based on TL values reported for the same animals that were analyzed in the present study and assuming that food webs were not isotopically distinct among the minke whale stocks, animals at SEG (TL ¼ 2.9), JM (TL ¼ 3.0), and WS (TL ¼ 3.1) were feeding at a significantly lower trophic level, i.e. primarily on krill, than at V/L (TL ¼ 3.4) and NS (TL ¼ 3.4) (Born et al., 2003). Therefore, the relatively low mean toxaphene values in female minke whales from SEG compared to animals from NS may to some extent be caused by the fact that they feed at a lower trophic level in that area. However, minke whales from the V/L area had the lowest toxaphene concentrations even though they have the highest TL value. This later observation suggests that trophic level values are not sufficient to explain adequately the spatial variations of the CHB contamination observed in minke whales. The seasonal fluctuation of body mass or, more specifically, of fat mass can result in the concentration or dilution of OCs in the body of marine mammals (Aguilar et al., 1999). Consequently, the sampling period needs to be considered, because some marine mammals are known to lose weight during the

breeding and molting periods, when the animals reduce their food intake (Kovacs et al., 1996; Reeves, 1998), or during the migration, when the animals have a high energetic demand (Beck et al., 1993). Minke whales in North Atlantic waters are known to migrate to northern feeding grounds in spring and early summer and to breeding areas in the south in autumn (Horwood, 1990). The information on the energetics of minke whales from North Atlantic waters is scarce, but significant seasonal increases in blubber thickness were observed in northeast Atlantic minke whales during the season of feeding (Næss et al., 1998). More exactly, the major part of fat deposition occurred between summer (15 June to 17 August) and autumn (25 August to 22 September), whereas lower seasonal changes were observed early in the season, that is between spring (15 April to 6 June) and summer (Næss et al., 1998). The study by Haug et al. (2002), supported this latter observation as no seasonal increase in blubber thickness was observed for animals from the Barents Sea and the Svalbard areas analyzed only for an early period (May 1st to June 30th) in the season. Similarly, for 237 stomachs of minke whales examined from Norwegian catches over 1943 to 1968 in North Atlantic waters, about 95% of empty stomachs were found from the Lofoten area and from animals sampled mainly in the early summer (Horwood, 1990). In this study, minke whales were sampled relatively early in the season (from May to June), at JM, WS, NS, and BS areas, whereas animals from SEG and WG (until October), and even V/L (until August) were sampled later in the season (Table 1). According to this information, the dilution of toxaphene in the body of minke whales from SEG, WG, and V/L areas should have been maximal, since these animals were supposed to be fattest during the sampling period. In contrast, the dilution of toxaphene in the body of minke whales from JM, WS, NS, and BS areas was minimal because these animals were supposed to be leanest during the sampling period. This suggests that the geographical distribution of toxaphene levels in minke whales examined in this study appears to be directly related to the sampling period of the animals within the year. To support this assumption, it would be interesting to study the variations of the toxaphene contamination in minke whales from a specific area collected over a wide time period. Unfortunately, the date of collection of each animal was not available. Nevertheless, another approach was used, which was to test the differences in toxaphene concentrations among areas assuming all animals had been collected late in the feeding season, i.e. in the fall. A significant seasonal increase of about 30e35% in blubber weight was reported for minke whales from Northeast Atlantic waters, including V/L, BS, and WS (Næss et al., 1998). Assuming that this increase is similar for minke whales from all parts of the North Atlantic waters, toxaphene concentrations in blubber of animals collected early in the feeding season, i.e. from JM, BS, WS, and NS areas, were divided by a factor of 1.5 to mimic the dilution due to the fattening of minke whales during the feeding season. Statistical analyses of the corrected sets of data indicate that significant differences in SCHB concentrations were still detected between sampling areas but only for female minke

B. Gouteux et al. / Environmental Pollution 153 (2008) 71e83

whales (ANOVA; p < 0.001). For males, the segregation of sampling areas was not statistically significant ( p ¼ 0.08). Furthermore, for females, the geographical trend was less clear since the mean toxaphene concentrations for animals from all areas, except WS, were statistically undistinguishable based on results from a Tukey’s post hoc test. These results tend to support the assumption that the sampling period of minke whales can be considered as a key factor accounting for the geographical distribution of toxaphene levels in minke whales examined in this study. Although the contamination of minke whales by other OCs than toxaphene should be similarly influenced by the sampling period of the animals, this link was not discussed by Hobbs et al. (2003a). It should be noted that this could modify notably the interpretation provided by these authors. For example, the general increase of concentrations of PCBs, DDT-, and chlordane related compounds in animals from west to east reported by the authors should be reconsidered. In contrast, the opposite trend observed for HCH concentrations would be amplified by considering the impact of the sampling period.

3.7. Geographical variation of toxaphene patterns PCA multivariate analysis of patterns of specific CHBs also showed groupings of sampling areas either for male or female minke whales (Fig. 3). The first two and three principal components explained more than 70% of the total variance for male and female animals, respectively. Male minke whales at WG and JM could be distinguished from animals at V/L, NS, and BS based on their higher proportions of P-31, B8-789, B8-531, B8-809, B9-1025, and B9-2206 (Fig. 3A). For females, a weak geographical segregation, mainly between the SEG area and the other areas, was shown based on relatively high loadings on principal components PC2 and PC3 due to higher proportions of P-31, B8-789, B8-531, B8-809, and B9-2206 (Fig. 3B). The interpretation of results for female animals should be done with caution since the partitioning of CHBs from the blubber may reflect their reproductive and lactation history. In fact, several studies have demonstrated that mothere offspring OC transfer was partly dependant on the physicochemical properties of the contaminants; more water-soluble contaminants being more efficiently transferred than less water-soluble contaminants (Espeland et al., 1997; Bernt et al., 1999; Debier et al., 2003b; Sørmo et al., 2003). Nevertheless, PCA plots for male animals provided a different perspective on geographical trends than those based on univariate analyses of toxaphene levels. Contrary to what the comparison of toxaphene levels revealed, the observed CHB patterns suggest there is a longitudinal gradient across the North Atlantic. The animals from the more westerly areas (WG and JM) have positive score for PC1, indicating that these animals have a higher proportion of CHBs with positive PC1 loadings (P-31, B8-531, B8-789, B8-809, B8-2229, B9-1025, and B92206) (Fig. 3A). In contrast, minke whales from the more easterly areas (NS, V/L, and BS) have negative scores for PC1. This

79

indicates that these animals have higher proportions of CHBs with negative PC1 scores (B8-1413 and B9-1679) (Fig. 3A). One of the reasons for such a longitudinal gradient could be the use of different commercial toxaphene mixtures in North America and Europe. There were a huge variety of technical products of toxaphene used in countries from both sides of the North Atlantic (Vetter and Oehme, 2000). Two of the most widely used mixtures were the Hercules 3956Ò formulation, mainly used in southeastern parts of the US (Li, 2001), and the MelipaxÒ formulation, mainly used in the former East Germany and the former Soviet Union (Li and Macdonald, 2005; Vetter et al., 2005). A recent paper has demonstrated that the relative proportions of some of the CHBs responsible for the longitudinal gradient shown in this study were remarkably similar in both formulations (Vetter et al., 2005). For instance, the contributions of B8-1413, a recalcitrant CHB, and B8-531, a degradable CHB, to both products were 0.44% and 0.44%, and 0.89% and 0.85%, respectively (Vetter et al., 2005). This suggests that differences in European versus North American technical products of toxaphene probably cannot explain the variation in CHB patterns observed in this study. Interestingly, several CHBs (P-31, B8-789, B8-531, B91025, and B9-2206) present in higher proportions in animals from WG and JM are known to be relatively unstable, while the two CHBs present in higher proportions in animals from NS, V/L, and BS are among the most recalcitrant toxaphene congeners. In fact, several studies have demonstrated that the degradation of CHBs is dependent on the chlorine substitution pattern of the six-member ring of CHB structure (Parlar et al., 2001). For instance, B8-1413 and B9-1679 which have only one chlorine atom in an alternating 2,3,5,6-endoeexo position at each carbon atom of the structure ring were found to be extremely stable in anaerobic soils or sewage sludge and to UV-radiation or biotransformation (Fingerling et al., 1996; Buser et al., 2000; Parlar et al., 2001). In contrast, B8-789 and B9-1025, which are characterized by two geminal dichloro groups on their structure, one being in position 10, are considered as susceptible to photodegradation. They can be degraded to chlorocamphene via a WagnereMeerwein rearrangement (Parlar et al., 2001). P-31 and B8-531 are also considered as very labile since they have a geminal dichloro group at the ring and one chlorine atom in the adjacent position (aposition) (Parlar et al., 2001). Finally, steric hindrance was shown to support the low persistency of CHBs having two exo-chlorine atoms vicinal to position 1 on the ring (i.e. 2-exo and 6-exo) such as B9-2206 (Vetter and Scherer, 1998). The higher proportion of degradable CHBs in minke whales from the most westerly sampling areas compared to the more easterly areas may also reflect the predominance of the US source for toxaphene inputs in the North Atlantic waters. Once released into the environment of the US or Europe, toxaphene is likely to be transported by major atmospheric pathways and/or ocean currents towards higher latitudes. The longer this transport is, the more the relatively labile CHBs are susceptible to be degraded. Hence, proportions of labile CHBs, for example P-31, B8-789, B8-531, B9-1025, and

B. Gouteux et al. / Environmental Pollution 153 (2008) 71e83

80

A

Factor scores

Factor loadings 1

PC 2 (17.1 %)

(Male)

2 B8-1413

JM

B9-1025

V/L

0

B8-809 B9-2206 B8-789 P-31 B8-531

0

NS

B9-1679

WG BS

B8-2229

-2

B8-1414/1945

-1 -2

0

2

-1

0

B

1

PC 1 (59.7 %)

PC 1 (59.7 %)

Factor loadings

Factor scores 1

2 B8-1413

PC 2 (21.8 %)

WS B9-1025 SEG

BS

0

B9-1679

P-31

0

WG

B8-809

B8-531 B9-2206 B8-789

NS JM

V/L

B8-1414/1945 B8-2229

-2

(Female)

-1

-2

0

2

-1

1

0

PC 1 (36.5 %)

PC 1 (36.5 %) 3

1 B9-1025

PC 3 (14.0 %)

P-31 JM B8-809

B9-1679

BS

B8-531

WS

0

B9-2206 B8-789

0 NS

B8-2229 B8-1414/1945

WG V/L

SEG B8-1413

-3

-1

-2

0

PC 1 (36.5 %)

2

-1

0

1

PC 1 (36.5 %)

Fig. 3. Results of principal component analysis showing mean scores ( standard deviation) and loadings of individual CHBs on Principal Components (PC) for (A) male and (B) female minke whales from each IWC ‘‘small areas’’. Values in brackets represent the percent variance explained by each PC.

B9-2206, should be lower in animals far away from sources, such as those from the most easterly sampling areas for the US source or those from the most westerly sampling areas for the European source. This should result in similar CHB patterns for animals from the whole North Atlantic if US and European sources of toxaphene were of equal importance. However, our results indicate that relatively labile CHBs were present in lower proportions in animals from V/L, NS, and BS

than in animals from the most westerly areas. This suggests that the US source of toxaphene to North Atlantic waters is quantitatively predominant. The history of the usage of toxaphene in the US and Europe tends to support this hypothesis. In fact, of the top 10 countries contributing to toxaphene usage on a global basis between 1947 and 2000, the US consumed the largest amounts (about 500 kt), mainly in southeastern states (Li, 2001; Li and Macdonald, 2005). In comparison,

B. Gouteux et al. / Environmental Pollution 153 (2008) 71e83

81

France and the former East Germany, which belong also to the top 10 countries, consumed only 26 and 22 kt of toxaphene, respectively (Li and Macdonald, 2005).

(The Danish Environmental Research Institute, Roskilde) for various help during the sampling and preparation of the samples.

4. Conclusion

References

This study showed that toxaphene, on a total toxaphene basis, is one of the predominant OCs in minke whales from the North Atlantic waters, reinforcing the need to consider this pesticide in the health assessment of marine mammal populations. In general, the contamination by toxaphene of minke whales from a specific North Atlantic area was in the midrange when compared to the contamination of other marine mammals inhabiting the same area. Minke whales appeared to be less contaminated than other cetacean species but more contaminated than seals. Even if very large variations in mean toxaphene concentrations were observed among sampling locations, only few significant differences in toxaphene concentrations were statistically significant among sampling areas for both male and female minke whales. Female animals from WG, SEG, and V/L areas were less contaminated than females from other areas, while only males from the V/L area could be differentiated from males from JM and NS. However, this apparent geographical discrimination in the toxaphene contamination of minke whales from North Atlantic waters may be considered as an artificial feature. In fact, much of this spatial variation can probably be explained by the seasonal fluctuation of minke whale fat mass due to seasonal differences in the sampling period of the animals. Patterns of CHBs in male minke whales revealed that animals from the more westerly areas (WG and JM) were distinct from minke whales from the more easterly areas (NS, V/L, and BS). Recalcitrant CHBs (B8-1413 and B9-1679) were present in higher proportions in male animals from NS, V/L, and BS and, inversely, relatively unstable CHBs (P-31, B8789, B8-531, B9-1025, and B9-2206) were in higher proportions in animals from WG and JM. This longitudinal trend may reflect differences between the US and European inputs of toxaphene into North Atlantic waters, the US input being quantitatively predominant. Acknowledgments This study was funded by the Danish Ministry of the Environment (Program: DANCEA ‘‘Danish Co-operation for Environment in the Arctic’’), the Greenland Institute of Natural Resources, and the Danish National Environmental Research Institute. We wish to thank the Greenland and Norwegian fishermen and hunters and others who helped to collect the samples. The co-operation during the sampling phase with the Directorate of Fisheries (Nuuk) and KNAPK (the Association of Greenland Hunters and Fishermen) is greatly acknowledged. Thanks to Karen Hobbs for organizing the data and to Sofie Jeremiassen and Kirsten Rydahl (The Greenland Institute of Natural Resources, Nuuk) and to Sigga Joensen, Else Marie Nielsen and Maja Kirkegaard

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