Organochlorine pesticides and polychlorinated biphenyls in California ...

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biphenyls in California sea lions. K. Kannan a,*, N. Kajiwara b. , B.J. Le Boeuf c. , S. Tanabe b. aWadsworth Center, New York State Department of Health and ...
Environmental Pollution 131 (2004) 425e434 www.elsevier.com/locate/envpol

Organochlorine pesticides and polychlorinated biphenyls in California sea lions K. Kannana,*, N. Kajiwarab, B.J. Le Boeufc, S. Tanabeb a

Wadsworth Center, New York State Department of Health and Department of Environmental Health and Toxicology, State University of New York at Albany, Empire State Plaza, PO Box 509, Albany, NY 12201-0509, USA b Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan c Department of Biology and Institute of Marine Sciences, University of California, Santa Cruz, CA 95064, USA Received 28 November 2003; accepted 5 March 2004

‘‘Capsule’’: PCB and DDT concentrations in California sea lions continue to be of concern. Abstract Concentrations of polychlorinated biphenyls (PCBs), DDTs, chlordanes, HCHs, hexachlorobenzene (HCB), dieldrin, heptachlor epoxide, tris(4-chlorophenyl)methane (TCPMe), and tris(4-chlorophenyl)methanol (TCPMOH) were measured in the blubber of California sea lions (Zalophus californianus) collected in 2000. DDTs were the most predominant contaminants, followed by PCBs, chlordanes, TCPMe, HCHs, TCPMOH, dieldrin, and heptachlor epoxide. Concentrations of PCBs and DDTs varied from a few mg/g to several hundreds of mg/g on a lipid weight basis. Concentrations of DDTs have declined by an order of magnitude over the last three decades in California sea lions; nevertheless, the measured concentrations of PCBs and DDTs in California sea lions are still some of the highest values reported for marine mammals in recent years. Concentrations of organochlorines were highly correlated with one another. Concentrations of PCBs and DDTs in the blubber of gray whale, humpback whale, northern elephant seal, and harbor seal, and in the adipose fat of sea otter, were lower than the levels found in California sea lions, and were in the range of a few to several mg/g on a lipid weight basis. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Organochlorines; PCBs; DDT; Sea lions; Marine mammal; California

1. Introduction Organochlorine pesticides and polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants that have been banned from production and use in most countries; however, considerable amounts continue to cycle in the ecosphere (Loganathan and Kannan, 1994; Ockenden et al., 2003). Since the ban in the 1970s, concentrations of organochlorine pesticides have declined in various ecosystems. Nevertheless, the rates of decline for organochlorines are relatively slow in marine ecosystems, which serve as a sink for organochlorine contaminants (Ballschmiter, 1992; Tanabe

* Corresponding author. Tel.: C1-518-474-0015; fax: C1-518-4732895. E-mail address: [email protected] (K. Kannan). 0269-7491/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2004.03.004

et al., 1994; Meijer et al., 2003). Therefore, marine animals, particularly those positioned at the top of the food web, accumulate great concentrations of these compounds and become vulnerable to the toxic effects (Loganathan and Kannan, 1991; Tanabe et al., 1994). Marine mammals have a number of biological traits that make them prone to accumulate great concentrations of PCBs and DDT: they feed at a high trophic level in the food web; they are warm-blooded, requiring high foodintake rates; they have lipid-rich blubber that efficiently retains and accumulates lipophilic contaminants; and they transfer much of the contaminant loads to offspring during nursing, resulting in trans-generational transfer of contaminants (Tanabe et al., 1988; Aguilar et al., 1999). Mass mortalities and declining stocks among several marine mammal populations from highly polluted areas have been attributed, in part, to contamination by organochlorine contaminants (Helle et al., 1976;

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Kannan et al., 1993; Corsolini et al., 1995; Ross et al., 1996; Jepson et al., 1999). California sea lions, Zalophus californianus californianus, are sentinels for monitoring levels of fat-soluble contaminants in the coastal waters of the western United States (Le Boeuf et al., 2002). Extraordinarily high concentrations of DDT were reported in California sea lions in the 1970s (Le Boeuf and Bonnell, 1971; DeLong et al., 1973; Gilmartin et al., 1976). From 1948 to 1970, the world’s largest DDT manufacturer discharged up to 20 tons of DDT wastes annually into the Los Angeles outfall on the Palos Verdes continental shelf along southern California. Since the ban on the manufacture of DDT in the United States, few studies have reported on the status of contamination in California sea lions (Lieberg-Clark et al., 1995). California sea lion blubber collected in the 1990s from the central California coast contained several tens to hundreds of mg/g of PCBs and DDTs (Kajiwara et al., 2001). This is despite the fact that the samples were collected from the central coast, rather than from more highly contaminated locations in southern California. The spatial variations and contemporary levels of organochlorines in California sea lions have not been studied in detail. In this study, we address this omission by evaluating current levels of organochlorine pesticides and PCBs in the blubber of 36 stranded California sea lions, collected between April and November 2000, from the northern, central and southern California coasts. In addition, effects of age, sex, and carcass condition on contaminant levels were examined. Temporal trends in PCB and DDT concentrations have been reported for these samples (Le Boeuf et al., 2002). Furthermore, samples of blubber of gray whale (Eschrichtius robustus), humpback whale (Megaptera nodosa), northern elephant seal (Mirounga augustirostris), and harbor seal (Phoca vitulina), and of adipose fat of sea otter (Enhydra lutris) were analyzed, to provide information on the current concentrations of organochlorines in these marine mammal species.

five animals were from the northern California counties of Marin, Mendocino, and Humboldt (Fig. 1). Sample composition by age and sex was: 17 adult males, five subadult males, six adult females, two juvenile females, four adults of unknown sex, and two animals of unknown sex and/or age. Adult males predominated in samples from all three regions in California. A tissue sample weighing approximately 150 g was excised from the medial ventrum region at the level of the axilla, from outer skin to muscle. Samples were deposited in clean jars and refrigerated until organochlorine analysis was conducted. Blubber of gray whale, humpback whale, northern elephant seal, and harbor seal, and adipose fat of sea otter, were collected from animals found stranded along the central coast of California in 2000. 2.2. Analysis Organochlorine analysis followed the established methods (Kajiwara et al., 2001). Blubber was extracted in a Soxhlet apparatus for 7 h with diethyl ether (300 mL) and hexane (100 mL). Fat content was determined from an aliquot of these extracts. The remaining extract was transferred to a gel permeation chromatography column (GPC; Bio-Beads S-X3, BioRad Laboratories, CA, 2 cm i.d. and 50 cm length) for lipid removal (Kajiwara et al., 2003). An equivalent mixture of dichloromethane and hexane (1:1 v/v) was used as a mobile phase at a flow rate of 5 mL/min. The first 120 mL was discarded. The second 100 mL fraction containing organochlorine compounds was collected, concentrated and passed through a 8-g activated Florisil packed glass column for fractionation. The first fraction

Shelter cove Mendocino

2. Materials and methods 2.1. Sample collection Blubber samples were collected from 36 dead California sea lions stranded on islands and along the coast of California between April and November 2000. The location, sex, estimated age category, and condition of each stranded animal was recorded. The condition of carcasses was characterized as fresh (n ¼ 17), moderately decomposed or less than two weeks dead (n ¼ 13), or highly (advanced) decomposed or more than two weeks dead (n ¼ 6). Seven animals were found on the Channel Islands in southern California, 24 animals were from An˜o Nuevo Island in central California, and

Marin

San Francisco Ano Nuevo Rio Del Mar La Selva Beach

Ancapa Is.

Santa Barbara Los Angeles

Santa Rosa Is. Santa Barbara Is. Santa Catalina Is. San Clemente Is. Fig. 1. Map of California, showing sampling locations of California sea lions.

K. Kannan et al. / Environmental Pollution 131 (2004) 425e434

eluted with hexane contained HCB, PCBs, p,p#DDE, and trans-nonachlor, while the second fraction eluted with 20% dichloromethane in hexane contained chlordane compounds (oxychlordane, cis-chlordane, cis-nonachlor), p,p#-DDD, p,p#-DDT, HCHs (a-, b-, gisomers), and TCPMe. The third fraction was collected with 50% dichloromethane in hexane for TCPMOH, dieldrin, and heptachlor epoxide. Each fraction was concentrated and injected into a gas chromatograph with electron capture detector (GC-ECD) or a gas chromatograph with a mass selective detector (GC-MSD) for quantification. Organochlorines in the first and second fractions (except TCPMe) were quantified by a GC-ECD (HewlettePackard 6890 Series) equipped with an auto injection system. The GC column employed was a DB-1 (J&W Scientific, Folsom, CA, USA) fused silica capillary (0:25 mm ! 30 m) coated with 100% dimethylpolysiloxane at 0.25 mm film thickness. The column oven temperature was programmed from 60 (C (1 min hold) to 160 (C, held for 10 min, and then increased to 260 (C at a rate of 2 (C/min, and held for 20 min. Injector and detector temperatures were set at 260 and 280 (C, respectively. Helium and nitrogen were used as the carrier and makeup gases, respectively. Organochlorine concentrations were calculated from the peak area of the sample to the corresponding external standard. The PCB standard used for quantification was an equivalent mixture of Kanechlor preparations (KC-300, KC-400, KC-500, KC-600) with known PCB composition and content. Concentrations of individually resolved peaks of PCBs isomers and congeners were summed to obtain total PCB concentrations. For the quantification of TCPMe and TCPMOH, a GC-MSD (HewlettePackard 6890 series GC coupled to 5973 MSD) was employed. Data were acquired by a HewlettePackard 5973C data system, in which the cluster ions were monitored at m/z 139, 251, 253, 362, 364 for TCPMOH and 311, 313, 346, 348 for TCPMe. Procedural blanks were analyzed simultaneously with samples, as a check for interferences or contamination from solvents and glassware. Recoveries of organochlorines through the analytical procedure ranged from 97 to 110% for pesticides, from 104 to 105% for TCPMe and TCPMOH, and from 92 to 109% for PCBs. A Standard Reference Material (SRM 1945; Gaithersburg, MD) was analyzed simultaneously for selected PCB congeners and organochlorine pesticides; the results were in agreement with the certified values. Detection limits for organochlorines analyzed in this study were in the range of 1e3 ng/g on a lipid weight basis. DDTs refers to sum of p,p#-DDE, p,p#DDT and p,p#-DDD; CHLs to sum of cis-chlordane, cis-nonachlor, trans-nonachlor, and oxychlordane; HCHs to sum of a-,b-, and g-isomers. Concentrations of organochlorines are presented on a lipid weight basis, unless specified otherwise.

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3. Results 3.1. California sea lions Concentrations of organochlorine pesticides and PCBs in the blubber of California sea lions are shown in Table 1. DDTs were the predominant contaminants in the blubber followed in decreasing order by PCBs, chlordanes (CHLs), TCPMe, HCHs, TCPMOH, dieldrin, and heptachlor epoxide. HCB was not found in any of the sea lion blubber at a detection limit of 1 ng/g, lipid wt. Lipid content in the blubber was 50 G 24% (mean G SD) and varied widely, from 2 to 88%. There was no significant difference in blubber lipid content among fresh (55 G 26%), moderately decomposed (50 G 20%), and highly decomposed (36 G 17%) carcasses (pO0:05). In fact, some of the extremely low lipid contents were found in fresh carcasses. Two individual California sea lions with the lowest levels of lipid in the blubber contained the highest concentrations of organochlorines analyzed. An inverse relationship was found between concentrations of DDTs and PCBs and lipid content of the blubber (Fig. 2). A similar trend was observed even when the samples containing !10% lipid or statistical outliers were omitted from the analysis. Concentrations of DDTs ranged from 4.1 to 1400 mg/g, lipid wt. The mean DDT concentration for the entire California sea lion sample was 143 mg/g, lipid wt (Table 1). The lowest concentration was found in an adult female sea lion collected from Anacapa Island in southern California, whereas the highest concentration was found in an adult female from An˜o Nuevo on the central California coast. The highest DDT concentration of 1400 mg/g, lipid wt, found in an adult female sea lion appears to qualify statistically as an outlier, as the concentration was approximately 5.5 standard deviations from the mean. However, as mentioned above, the lipid content in the blubber of this individual dolphin was 5.5-times less than the standard deviation of the mean lipid content of the population. Furthermore, such observations of high concentrations in a few individuals are common, as reported in earlier studies from California coast (Nakata et al., 1998; Kajiwara et al., 2001; Le Boeuf et al., 2002). Therefore, this individual was not removed from further analysis of data. There were no significant differences in mean DDT concentrations among animals collected from southern, central and northern California (two-tailed t test; p > 0:05). Similarly, no significant difference in DDT concentration was observed between carcasses that were fresh and moderately decomposed, or between fresh and highly decomposed (two-tailed t test; p > 0:05). DDT concentrations did not significantly differ among adult males, subadult males, and adult females (p > 0:05). A similar pattern of no significant differences among

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Table 1 Mean (G one standard deviation) organochlorine concentrations (mg/g, lipid wt) in the blubber of California sea lions collected from the California coasta n

% Lipid

PCBs

DDTs

CHLs

Heptachlor epoxide

TCPMe

TCPMOH

HCHs

Dieldrin

Overall

36

50 G 24 39a

44.1 G 76.7 23.1

143 G 253 69

3.42 G 6.68 1.72

0.18 G 0.28 0.10

2.73 G 6.14 0.95

0.55 G 0.79 0.28

0.78 G 1.46 0.40

0.19 G 0.22 0.11

North

5

Central

24

55 G 17 52 49 G 25 38 52 G 22 36

35.7 G 20.3 30.7 53.4 G 91.5 26.3 17.9 G 15 12.0

127 G 92.4 99.2 170 G 301 80 60.7 G 57 33.0

3.3 G 2 2.8 4.1 G 8 2.0 1.11 G 0.79 0.68

0.19 G 0.07 0.18 0.22 G 0.34 0.13 0.06 G 0.04 0.03

2.8 G 2.7 1.5 3.4 G 7.3 1.1 0.56 G 0.37 0.40

0.54 G 0.31 0.46 0.61 G 0.93 0.31 0.33 G 0.33 0.13

0.83 G 0.48 0.72 0.94 G 1.74 0.49 0.19 G 0.14 0.12

0.20 G 0.13 0.17 0.20 G 0.25 0.12 0.14 G 0.15 0.07

43 G 93 19 30 G 28

143 G 317 57 88 G 77

3.83 G 9.33 1.41 2.22 G 2

0.19 G 0.38 0.08 0.15 G 0.16

3.14 G 8.28 0.80 1.27 G 1.41

0.59 G 1.06 0.25 0.43 G 0.39

0.84 G 2.01 0.31 0.63 G 0.71

0.18 G 0.28 0.09 0.18 G 0.14

Location

Condition

Sex/age group

a

South

7

Fresh

17

Moderate decomposition

13

55 G 26 40 50 G 20

Advanced decomposition

6

45 36 G 17

21 79 G 87

60 262 G 256

1.53 4.82 G 2.51

0.10 0.24 G 0.12

0.72 4.71 G 4.33

0.26 0.68 G 0.43

0.41 0.93 G 0.47

0.11 0.25 G 0.18

26

50

162

3.88

0.20

2.87

0.46

0.76

0.20

51 G 23 40 54 G 25 40 44 G 17 41

45 G 66 24 83 G 147 23 20 G 6.25 19.1

140 G 194 72 283 G 501 70 63.40 G 24.1 57.5

2.77 G 2.26 1.79 8.20 G 14.7 1.89 1.48 G 0.55 1.33

0.16 G 0.11 0.11 0.36 G 0.6 0.10 0.12 G 0.04 0.11

2.29 G 3.25 1.00 6.81 G 13.1 1.15 1.15 G 1.21 0.67

0.44 G 0.37 0.25 1.11 G 1.64 0.31 0.31 G 0.21 0.24

0.58 G 0.35 0.43 1.80 G 3.14 0.44 0.40 G 0.21 0.36

0.17 G 0.15 0.12 0.28 G 0.42 0.09 0.10 G 0.08 0.07

Adult male

17

Adult female

6

Subadult male

5

Geometric mean is in bold.

K. Kannan et al. / Environmental Pollution 131 (2004) 425e434

Category

DDT or PCB concentration (µg/g lipid wt.)

K. Kannan et al. / Environmental Pollution 131 (2004) 425e434

PCB y = 139 - 1.89x DDT y = 442 - 5.9x

1200

800

400

0 10

30

50

70

90

Lipid content (%) Fig. 2. Relationship between DDT and PCB concentrations and lipid content in the blubber of California sea lions. (Note: A negative correlation was also found when the two outliers were removed from the analysis).

collection locations, gender, age, or carcass condition was observed for wet weight-based concentrations. p,p#DDE accounted for a major proportion of the total DDT concentrations in the blubber (Fig. 3). PCBs were the second most abundant contaminants in California sea lion blubber. Overall, the total PCB concentration (44:1 G 76:7 mg=g, lipid wt) was 3-fold lower than the DDT concentrations (143 G 253 mg=g, lipid wt). An adult female California sea lion that contained the highest DDT concentration, also contained the greatest PCB concentration of 410 mg/g, lipid wt, in its blubber. The mean PCB concentration was higher in animals collected in central California (53:4 G 91:5 mg=g, lipid wt) than in those from northern (35:7 G 20:3 mg=g) or southern California (17:9 G 15 mg=g). PCB concentrations by age/gender groups were as follows: adult females (83 G 147 mg=g) O adult males (45 G 66 mg=g)

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O subadult males (20 G 6:25 mg=g). However, the differences were not statistically significant (p > 0:05). Mean PCB concentration did not vary significantly according to carcass condition: highly decomposed (79 G 87 mg=g) O freshly dead (43 G 93 mg=g) > moderately decomposed (30 G 28 mg=g). Chlordanes (CHLs) were the third most abundant contaminants in California sea lion blubber. On a wetweight basis, total CHL concentrations varied from 0.05 to 2.2 mg/g, comparable to those values reported for marine mammals from other parts of the world. Transnonachlor accounted for, on average, 86% of the total CHL concentrations. This was followed by oxychlordane (7%), cis-nonachlor (4.6%), and cis-chlordane (2.3%) (Fig. 3). TCPMe concentrations of up to 36 mg/g, lipid wt, were measured in California sea lion blubber. A significant positive correlation between total DDT and TCPMe C TCPMOH concentrations was found (Fig. 4). The correlation was significant when the TCPMe (r2 ¼ 0:71) and TCPMOH (r2 ¼ 0:69) concentrations were plotted against DDT concentrations individually. Concentrations of HCHs, dieldrin, and heptachlor epoxide in California sea lions were relatively lower than the levels of other organochlorines. A significant correlation was observed among the concentrations of various organochlorines in the blubber of California sea lions (Table 2).

3.2. Other marine mammals DDT was the major contaminant in sea otter, elephant seal, humpback whale, and harbor seal (Table 3). However, gray whale contained 3-fold higher concentration of PCBs than DDTs. Concentrations of most organochlorines were much greater in gray whales than in sea otters, elephant seals, harbor seals, or humpback whales. Relatively high concentrations, coupled with a

Fig. 3. Composition (%) of DDTs, chlordanes, and HCHs and in the blubber/fat tissue of various marine mammal species collected along the California coast.

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0.46 0.53 0.66 0.56 0.6 0.64 1

0.046 0.003 0.028 0.007 0.090 0.020 0.007 0.042 0.006 0.13 0.011 0.005 0.12 0.22 2.1 17 1.4 9.4 29 87 Fresh stranded Fresh stranded

0.043 0.037 0.20 0.068 0.041 0.032 1.9 19 9.4 84 Fresh stranded Yearling

Adult/154 F

M

F

7.6 0.022 1.3 0.019 3.3 0.044 0.038 0.004 0.009 0.003 0.25 0.012 6.9 0.29 14 3.0 36 1.8 0.83 86

0.014 0.11 0.24 0.048 0.037 0.060

Weanling/162

CHLs DDTs PCBs

Central coast La Selva Beach

0.77 0.81 0.96 0.88 0.91 1

May 2000 Apr. 2000

0.8 0.87 0.92 0.88 1

An˜o Nuevo, CA

0.92 0.95 0.95 1

May 2000

0.84 0.89 1

Scott Creek Rio del Mar

0.99 1

Apr. 2000 Apr. 2000

PCBs DDTs CHLs TCPMe TCPMOH HCHs Dieldrin PCBs 1 DDTs CHLs TCPMe TCPMOH HCHs Dieldrin

Gray whale Northern elephant seal (1) Northern elephant seal (2) Humpback whale Harbor seal

Table 2 Correlation (r2 value) matrix of organochlorine concentrations in California sea lion blubber

Nov. 2000

Concentrations of organochlorines in the blubber of marine mammals have been associated with lipid content (Aguilar et al., 1999). In stranded and diseased marine mammals, lipid content in the blubber is often lower than that found in healthy animals. Several individuals of adult California sea lions analyzed in this study had a blubber lipid content of !20%. Relatively low lipid levels, and wide variation in lipid content, in the blubber of California sea lions have been reported

Sea otter

4. Discussion

Table 3 Concentrations (mg/g, lipid weight) of organochlorines in marine mammals from coastal California

high PCB/DDT ratio, suggest that gray whale had exposures from other locations. The composition of DDTs, chlordanes and HCHs in gray and humpback whales and harbor seals were different from those determined for California sea lions (Fig. 3). The compositions of p,p#-DDT and a-HCH were much greater in harbor seals than in other marine mammals analyzed in this study. Humpback whales contained a greater proportion of p,p#-DDD and a-HCH. The composition of oxychlordane was greater in seals and whales than in California sea lions.

Heptachlor epoxide

Fig. 4. Relationship between DDT and (TCPMe C TCPMOH) concentrations (mg/g, lipid weight) in the blubber of California sea lions.

0.63

300

Lipid (%)

250

Condition

200

Age/ length (cm)

150

Sex

100

DDT Concentration

Location

50

Date of collection

0

TCPMe

0

An˜o Nuevo, CA

2

17

TCPM OH

4

3.7

HCHs

6

4.6

Dieldrin

y = 0.022x - 0.08 R2 = 0.79

8

Species

Concentration of TCPMe + TCPMOH

10

Moderate decomposition Fresh stranded Fresh stranded

HCB

K. Kannan et al. / Environmental Pollution 131 (2004) 425e434

K. Kannan et al. / Environmental Pollution 131 (2004) 425e434

earlier (Kajiwara et al., 2001). We found no relationship between lipid content and carcass condition ( fresh or decomposed). Thus, the low lipid content in several individuals may have resulted from the mobilization of fat reserves from the blubber, prior to the death due to starvation or disease. Those individuals that contained the lowest lipid content had very high concentrations of organochlorines, as has been reported in earlier studies (Corsolini et al., 1995; Kajiwara et al., 2001). It is expected that lipophilic contaminants will be mobilized along with lipids during starvation or disease (Aguilar and Borrell, 1994). However, the presence of high concentrations of organochlorines in individuals with low lipid content does not support this hypothesis. Borrell and Aguilar (1990) found a trend of increasing blubber organochlorine concentration with progression of carcass decomposition, for striped dolphins. Similarly, a negative correlation between organochlorine levels and blubber thickness has been reported in Caspian and harbor seals (Hall et al., 1999). The decrease in blubber lipid content, with concomitant increase in organochlorine residues, suggests a lack of equilibrium in the distribution of organochlorines in diseased marine mammals. Several hypotheses have been suggested for this cause/effect (Aguilar and Borrell, 1994). In addition, it is possible that the rates of mobilization of polar and non-polar lipids may be different in starved individuals. Organochlorines preferentially bind to non-polar lipids (e.g., triacylglycerols); thus, characterization of the composition of lipids in diseased individuals may provide some explanation. Further, it is possible that high PCB concentrations lead to peroxidation of lipids, resulting in lipid catabolism. Laboratory studies with mink and rat have shown peroxidation of lipids following exposure to PCBs (Kakela et al., 2001; Fadhel et al., 2002). Superoxide or hydrogen peroxide released as a by-product from cytochrome P450 enzyme activities contributes to lipid peroxidation. The mean concentration of DDT in California sea lions was approximately 10 times lower than the concentration (1450 mg/g, lipid wt) reported in 1970 by Le Boeuf and Bonnell (1971). The pattern of decrease in DDT levels in California sea lions over the last three decades is similar to the trend observed in other marine species from other parts of the world (Blomkvist et al., 1992; Kannan et al., 1992; Bignert et al., 1993; Muir et al., 1996). The decrease is not by as much as two orders of magnitude, as was claimed by Lieberg-Clark et al. (1995); that study was unrepresentative, based on only a small sample (O’Shea and Brownell, 1998). Despite the marked decline in DDT residues in California sea lions over the last three decades, concentrations remain higher in this species than in most other marine mammals (Prudente et al., 1997). No threshold concentration for DDT is available to evaluate potential effects of DDTs measured in California sea lions. DDTs have

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been reported to induce estrogenic as well as antiandrogenic effects in several species (Kelce et al., 1995). DDTs have been shown to elicit glucocorticolysis at w13 mg/g, wet wt, in adrenal gland of seals (Lund, 1994). Thirty of the 36 California sea lions analyzed in this study contained blubber DDT concentrations greater than 13 mg/g on a wet-weight basis. Similarly, in vitro proliferative response of beluga whale splenocytes cultured with phytohemagglutinin was significantly reduced, at 25 mg/g of DDT (De Guise et al., 1998). The measured concentrations of DDT in California sea lions are considerably higher than the minimum concentrations that have been reported to elicit adverse effects in laboratory exposure studies. Concentrations of total PCBs in the blubber of adult female sea lions collected from southern California in 1970 were as high as 133 mg/g, lipid wt (DeLong et al., 1973). The mean PCB concentration in the blubber of California sea lions collected from the central California coast during 1991e1997 was 360 mg/g, lipid wt (Kajiwara et al., 2001), a level 5-fold greater than that measured in the present study. The decline in PCB concentrations, relative to the trend for DDTs, in California sea lions appears to be slow, as has been observed for marine species from several locations (Loganathan et al., 1990; Loganathan and Kannan, 1991; Kannan et al., 1992; Muir et al., 1996; Addison and Stobo, 2001). The mean concentration of PCBs (44:1 G 76:7 mg=g, lipid wt) remains more than double the threshold concentration of 17 mg/g, lipid wt, that elicits physiological effects in marine mammals (Kannan et al., 2000). Elevated concentrations of TCPMe and TCPMOH in California sea lions are in accordance with high concentrations of DDT, a potential source for TCPMe in the environment (Buser, 1995). The mean TCPMe concentration of 2:73 G 6:14 mg=g, lipid wt, was one to two orders of magnitude greater than the levels found in various pinniped species from several other locations (Watanabe et al., 2000). The concentration of TCPMOH is approximately 5-fold lower than the TCPMe concentration in California sea lions. However, TCPMOH concentrations were greater than TCPMe concentrations in sea otters, gray whale, humpback whale, and elephant seals. The ratios of TCPMe to TCPMOH vary depending on the species, possibly due to differences in the metabolic potential or sources of exposure (Falandysz et al., 1999; Watanabe et al., 2000; Kajiwara et al., 2001). Potential sources of TCPMe and TCPMOH are considered to be DDT preparation, dicofol and related agrochemicals, and large synthetic polymers and lightfast dyes for acrylic fibers (Buser, 1995). A significant relationship between TCPMe/TCPMOH ratio and DDT concentration suggests that DDT is a source for these compounds in California sea lions. The concentration of TCPMe in a technical DDT preparation was less than 0.01% (Buser, 1995; Falandysz et al., 1999). Nevertheless,

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TCPMe accounted for 1.9% (0.53e4.9%) of the total DDT concentrations in the blubber of California sea lions. This indicates the presence of sources other than DDT mixtures, and/or preferential enrichment and biomagnification of TCPMe/TCPMOH, in pinnipeds. Differences in ratios of TCPMe/TCPMOH as well as TCPMe/DDT suggest the presence of multiple sources of these compounds in the environment. TCPMe and TCPMOH, due to their high concentrations and estrogenic effects, are major contaminants in California coastal waters, and merit further study, to elucidate their dynamics, fate, and effects along the California coast. Few studies have reported the occurrence of CHLs in marine mammals from the California coast. Concentrations of CHLs in sea lion blubber (0.084e41 mg/g, lipid wt) were within the range of values observed in an earlier study (0.51e86 mg/g, lipid wt) (Kajiwara et al., 2001), but were greater than levels measured in livers of California sea otters (0.05e21 mg/g, lipid wt) (Nakata et al., 1998). Overall, organochlorine concentrations varied widely in California sea lions; location, carcass condition, age, and gender were not major confounders, although the sample sizes were probably small for a significant relationship to be detectable. California sea lions collected in southern California, close to the Palos Verdes Shelf, had contaminant levels comparable to those of sea lions collected in central and northern California. This may be explained in part by the extensive annual movements of sea lions up and down the coast, and the widespread movements of their prey. Great individual variation in contaminant levels was observed in the current sample, as well as in samples obtained during the early 1970s. This variation is not explained by age and sex differences, whichdalthough predicteddwere not evident in this sample. Individual feeding preferences might explain part of this variation. The variability implies that sea lions get their contaminant loads from their prey that feed over a wide area, rather than directly from the point sources in southern California. The principal prey of California sea lions are northern anchovy, Pacific whiting, mackerel, rockfish, and market squid, which migrate both vertically and horizontally along the California coast (Lowry et al., 1991). As a consequence, the concentrations reported here may not necessarily reflect the contamination levels of prey in the area where the individual sea lions stranded. The large inter-individual variability in the data may indicate variation in foraging area, or prey species, or temporal differences in exposure. A significant correlation among the various organochlorines analyzed in this study suggests co-exposure of California sea lions to a wide variety of persistent compounds, a pattern which may be due to co-occurrence of contaminants in certain locations. Preference of individual sea lions for diet from certain locations may result in exposure to a myriad of contaminants

simultaneously. In addition to the high levels of PCBs and DDTs found in sea lions, exposure to a myriad of other toxic contaminants may affect the health and survival of individuals. Therefore, evaluation of health effects in sea lions should consider effects associated with exposure to complex mixtures. Concentrations of organochlorine pesticides and PCBs were relatively low in elephant seals and humpback whale, among the other marine mammals that were analyzed. On a wet-weight basis, concentrations of PCBs and DDT in gray whale blubber were 0.3 and 0.12 mg/g, respectively. These values are within the range of values reported in the blubber of gray whale collected along the west coast of the United States during 1988e1991 (0.12e10 mg/g for PCBs and 0.009 to 2.1 mg/g for DDTs) (Varanasi et al., 1994). The PCB/DDT ratio in gray whale was O1, whereas that in other marine mammals was !1. Higher concentrations of PCBs than DDTs in gray whales suggest exposures in northern locations. In addition, concentrations of HCHs, dieldrin, and heptachlor epoxide were considerably higher in gray whales than in other marine mammals analyzed. Gray whales migrate to the California coast from northern locations such as the Bering and Chuckchi Seas during December to April. Bowhead whales and Beluga whales collected from the Beaufort and Chuckchi Seas contained higher concentrations of PCBs than DDTs (Hoekstra et al., 2003). PCB and DDT concentrations in the blubber of an adult female harbor seal collected near La Selva Beach in central California were 9.4 and 17 mg/g, lipid wt, respectively. The compositions of p,p#-DDT and a-HCH were much greater in harbor seal than in other marine mammals analyzed in this study. These results suggest exposure to relatively new sources of DDTs and of HCHs, and that these exposures occurred in different locations. A similar trend was found in an earlier study (Kajiwara et al., 2001). Although the number of samples analyzed is small, the data presented here establish a baseline for future monitoring of these contaminants in whales and seals.

References Addison, R.F., Stobo, W.T., 2001. Trends in organochlorine residue concentrations and burdens in grey seals (Halichoerus grypus) from Sable Is., NS, Canada, between 1974 and 1994. Environ. Pollut. 112, 505e513. Aguilar, A., Borrell, A., 1994. Abnormally high polychlorinated biphenyl levels in striped dolphins (Stenella coeruleoalba) affected by the 1990e1992 Mediterranean epizootic. Sci. Total Environ. 154, 237e247. Aguilar, A., Borrell, A., Pastor, T., 1999. Biological factors affecting variability of persistent pollutant levels in cetaceans. J. Cetacean Res. Manage. 1, 83e116. Ballschmiter, K., 1992. Transport and fate of organic compounds in the global environment. Angew. Chem. Int. Ed. Engl. 31, 487e515.

K. Kannan et al. / Environmental Pollution 131 (2004) 425e434 Bignert, A., Go¨thberg, A., Jensen, S., Litze´n, K., Odsjo¨, T., Olsson, M., Reuterga˚rdh, L., 1993. The need for adequate biological sampling in ecotoxicological investigations: a retrospective study of twenty years pollution monitoring. Sci. Total Environ. 128, 121e139. Blomkvist, G., Roos, A., Jensen, S., Bignert, A., Olsson, M., 1992. P Concentrations of DDT and PCB in seals from Swedish and Scottish waters. Ambio 21, 539e545. Borrell, A., Aguilar, A., 1990. Loss of organochlorine compounds in the tissues of a decomposing stranded dolphin. Bull. Environ. Contam. Toxicol. 45, 46e53. Buser, H.R., 1995. DDT, a potential source of environmental tris (4-chlorophenyl) methane and tris (4-chlorophenyl) methanol. Environ. Sci. Technol. 29, 2133e2139. Corsolini, S., Focardi, S., Kannan, K., Borrell, A., Tanabe, S., Tatsukawa, R., 1995. Congener profile and toxicity assessment of polychlorinated biphenyls in dolphins, shark and tuna collected from Italian coastal waters. Mar. Environ. Res. 40, 33e53. De Guise, S., Martineau, D., Be´land, P., Fournier, M., 1998. Effects of in vitro exposure of beluga whale leukocytes to selected organochlorines. J. Toxicol. Environ. Health 55, 479e493. DeLong, R.L., Gilmartin, W.G., Simpson, J.G., 1973. Premature births in California sea lions: association with high organochlorine pollutant residue levels. Science 181, 1168e1170. Fadhel, Z., Lu, Z., Robertson, L.W., Glauert, H.P., 2002. Effect of 3,3#,4,4#-tetrachlorobiphenyl and 2,2#,4,4#,5,5#-hexachlorobiphenyl on the induction of hepatic lipid peroxidation and cytochrome P-450 associated enzyme activities in rats. Toxicology 175, 15e25. Falandysz, J., Strandberg, B., Strandberg, L., Rappe, C., 1999. Tris(4chlorophenyl)methane and tris(4-chlorophenyl)methanol in sediment and food webs from the Baltic south coast. Environ. Sci. Technol. 33, 517e521. Gilmartin, W.G., DeLong, R.L., Smith, A.W., Sweeney, J.C., De Lappe, B.W., Risebrough, R.W., Griner, L.A., Dailey, M.D., Peakall, D.B., 1976. Premature parturition in the California sea lion. J. Wildl. Dis. 12, 104e114. Hall, A.J., Duck, C.D., Law, R.J., Allchin, C.R., Wilson, S., Eybator, T., 1999. Organochlorine contaminants in Caspian and harbor seal blubber. Environ. Pollut. 106, 203e212. Helle, E., Olsson, M., Jensen, S., 1976. DDT and PCB levels and reproduction in ringed seals from the Bothnian Bay. Ambio 5, 188e189. Hoekstra, P.F., O’Hara, T.M., Fisk, A.T., Borga˚, K., Solomon, K.R., Muir, D.C.G., 2003. Trophic transfer of persistent organochlorine contaminants (OCs) within an Arctic marine food web from the southern BeauforteChukchi Seas. Environ. Pollut. 124, 509e522. Jepson, P.D., Bennett, P.M., Allchin, C.R., Law, R.J., Kuiken, T., Baker, J.R., Rogan, E., Kirkwood, J.K., 1999. Investigating potential associations between chronic exposure to polychlorinated biphenyls and infectious disease mortality in harbour porpoises from England and Wales. Sci. Total Environ. 244, 339e348. Kajiwara, N., Kannan, K., Muraoka, M., Watanabe, M., Takahasi, S., Gulland, F., Olsen, H., Blankenship, A.L., Jones, P.D., Tanabe, S., Giesy, J.P., 2001. Organochlorine pesticides, polychlorinated biphenyls, and butyltin compounds in blubber and livers of stranded California sea lions, elephant seals, and harbor seals from coastal California, USA. Arch. Environ. Contam. Toxicol. 41, 90e99. Kajiwara, N., Ueno, D., Monirith, I., Tanabe, S., Pourkazemi, M., Aubrey, D.G., 2003. Contamination by organochlorine compounds in sturgeons from Caspian Sea during 2001 and 2002. Mar. Pollut. Bull. 46, 741e747. Kakela, R., Kinnunen, S., Kakela, A., Hyvarinen, H., Asikainen, J., 2001. Fatty acids, lipids, and cytochrome P-450 monooxygenase in hepatic microsomes of minks fed fish-based diets and exposed to Aroclor 1242. J. Toxicol. Environ. Health A 64, 427e446.

433

Kannan, K., Tanabe, S., Borrell, A., Aguilar, A., Focardi, S., Tatsukawa, R., 1993. Isomer-specific analysis and toxic evaluation of polychlorinated biphenyls in striped dolphins affected by an epizootic in the western Mediterranean Sea. Arch. Environ. Contam. Toxicol. 25, 227e233. Kannan, K., Blankenship, A.L., Jones, P.D., Giesy, J.P., 2000. Toxicity reference values for the toxic effects of polychlorinated biphenyls to aquatic mammals. Human Ecol. Risk Assess. 6, 181e201. Kannan, K., Falandysz, J., Yamashita, N., Tanabe, S., Tatsukawa, R., 1992. Temporal trends of organochlorine concentrations in codliver oil from the southern Baltic Proper, 1971e1989. Mar. Pollut. Bull. 24, 358e363. Kelce, W.R., Christy, R.S., Laws, S.C., Gray, L.E., Kemppainen, J.A., Wilson, E.M., 1995. Persistent DDT metabolite p,p#-DDE is a potent androgen receptor. Nature 375, 581e585. Le Boeuf, B.J., Bonnell, M.L., 1971. DDT in California sea lions. Nature 234, 108e110. Le Boeuf, B.J., Giesy, J.P., Kannan, K., Kajiwara, N., Tanabe, S., Debier, C., 2002. PCB and DDT in California sea lions revisted. BMC Ecol. 2 (11), 1e8. Lieberg-Clark, P., Bacon, C.E., Burns, S.A., Jarman, W.M., LeBoeuf, B.J., 1995. DDT in California sea lions: A follow up study after twenty years. Mar. Pollut. Bull. 30, 744e745. Loganathan, B.G., Kannan, K., 1991. Time perspectives of organochlorin contamination in the global environment. Mar. Pollut. Bull. 22, 582e584. Loganathan, B.G., Kannan, K., 1994. Global organochlorine contamination trends: an overview. Ambio 23, 187e191. Loganathan, B.G., Tanabe, S., Tanaka, H., Watanabe, S., Miyazaki, N., Amano, M., Tatsukawa, R., 1990. Comparison of organochlorine residue levels in the striped dolphin from western North Pacific, 1978e79 and 1986. Mar. Pollut. Bull. 21, 435e439. Lowry, M.S., Stewart, B.S., Heath, C.B., Yochem, P.K., Francis, J.M., 1991. Seasonal and annual variability in the diet of California sea lions Zalophus californianus at San Nicolas Island, California, 1981e86. Fishery Bull. 89, 331e336. Lund, B.-O., 1994. In vitro adrenal bioactivation and effects on steroid metabolism of DDT, PCBs and their metabolites in the gray seal (Halichoerus grypus). Environ. Toxicol. Chem. 13, 911e917. Meijer, S.N., Ockenden, W.A., Sweetman, A., Breivik, K., Grimalt, J.O., Jones, K.C., 2003. Global distribution and budget of PCBs and HCB in background surface soils: implications or sources and environmental processes. Environ. Sci. Technol. 37, 667e672. Muir, D.C.G., Koczanski, K., Rosenberg, B., Be´land, P., 1996. Persistent organochlorines in beluga whales (Delphinapterus leucas) from the St. Lawrence River estuarydII. Temporal trends. Environ. Pollut. 93, 235e245. Nakata, H., Kannan, K., Jing, L., Thomas, N., Tanabe, S., Giesy, J.P., 1998. Accumulation pattern of organochlorine pesticides and polychlorinated biphenyls in southern sea otters (Enhydra lutris nereis) found stranded along coastal California, USA. Environ. Pollut. 103, 45e53. O’Shea, T.J., Brownell Jr., R.L., 1998. California sea lion (Zalophus californianus) populations and DDT contamination. Mar. Pollut. Bull. 36, 159e164. Ockenden, W.A., Breivik, K., Meijer, S.N., Steinnes, E., Sweetman, A.J., Jones, K.C., 2003. The global re-cycling of persistent organic pollutants is strongly retarded by soils. Environ. Pollut. 121, 75e80. Prudente, M., Tanabe, S., Watanabe, M., Subramanian, A., Miyazaki, N., Suarez, P., Tatsukawa, R., 1997. Organochlorine contamination in some odentoceti species from the North Pacific and Indian Ocean. Mar. Environ. Res. 44, 415e427. Ross, P.S., De Swart, R.L., Addison, R., Van Loveren, H., Vos, J., Osterhaus, A., 1996. Contaminant-induced immunotoxicity in harbor seals: wildlife at risk? Toxicology 112, 157e169.

434

K. Kannan et al. / Environmental Pollution 131 (2004) 425e434

Tanabe, S., Iwata, H., Tatsukawa, R., 1994. Global contamination by persistent organochlorines and their ecotoxicological impact on marine mammals. Sci. Total Environ. 154, 163e177. Tanabe, S., Watanabe, S., Tatsukawa, R., 1988. Capacity and mode of PCB metabolism in small cetaceans. Mar. Mamm. Sci. 4, 103e124. Varanasi, U., Stein, J.E., Tilbury, K.L., Meador, J.P., Sloan, C.A., Clark, R.C., Chan, S.-L., 1994. Chemical contaminants in gray

whales (Eschrichtius robustus) stranded along the west coast of North America. Sci. Total Environ. 145, 29e53. Watanabe, M., Kannan, K., Takahashi, A., Loganathan, B.G., Odell, D.K., Tanabe, S., Giesy, J.P., 2000. Polychlorinated biphenyls, organochlorine pesticides, tris(4-chlorophenyl)methane and tris(4chlorophenyl)methanol in livers of small cetaceans stranded along Florida coastal waters, USA. Environ. Toxicol. Chem. 19, 1566e1574.