p,p -DDE in Bluefin Tuna, Swordfish,

Transcription

1 Report Kurunthachalam Kannan, Simonetta Corsolini, Takashi Imagawa, Silvano Focardi and John P. Giesy Polychlorinated -Naphthalenes, -Biphenyls, -Dibenzo-p-dioxins, -Dibenzofurans and p,p -DDE in Bluefin Tuna, Swordfish, Cormorants and Barn Swallows from Italy Concentrations of p,p -DDE, polychlorinated biphenyl congeners (PCBs), polychlorinated-dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs) and -naphthalenes (PCNs) were measured in bluefin tuna, swordfish, common cormorants, and barn swallows collected from Italy. Average concentrations of PCBs in livers of tuna, swordfish, cormorant, and swallows were 930, 745, 1420 and 1230 ng PCBs g 1, w.w. respectively. p,p -DDE was found in tuna, swordfish, cormorant, and swallow livers at mean concentrations of 82, 135, 166 and 95 ng DDE g 1, w.w. respectively. PCNs were found in all the samples analyzed, although at concentrations less than those reported for biota from the Baltic Sea. PCBs, particularly, non-ortho coplanar PCBs accounted for 80 90% of the total TEQs in tuna and swordfish. Relative contribution of PCDDs/DFs to TEQs was greater in cormorants and swallows compared to that in fishes. PCDD/DF congeners accounted for up to 80 and 45% of the total TEQs in cormorants and swallows, respectively. INTRODUCTION Notable concentrations of polychlorinated biphenyls (PCBs) and DDT have been reported in tissues of dolphins found stranded along the Italian coast of the Mediterranean Sea (1-3). Concentrations of PCBs reported in the blubber of cetaceans from the Italian coast of the Mediterranean Sea were greater than a threshold value, to elicit physiological effects in aquatic mammals of 11 µg g 1, w.w. (4). While studies have measured concentrations of PCBs and DDTs in cetaceans, exposure to these compounds in other coastal species, particularly tuna, swordfish, and cormorants is less known. Monitoring of contaminants is essential in view of the fact that the tuna fishery is a major commercial industry in coastal Italy. Consumption of tuna or swordfish containing high concentrations of PCBs or other toxic compounds may have implications for human health. Apart from PCBs and DDTs, no studies have reported concentrations of polychlorinated-dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs) or - naphthalenes (PCNs) in fishes from the Italian coast. Furthermore, bird species such as cormorants and swallows have been used as indicators to monitor aquatic pollution by chlorinated organics (5, 6). The objectives of this study were to determine concentrations and congener profiles of organochlorines that elicit dioxin-like toxicity, and their corresponding toxic equivalents in fishes and birds from the Italian coast of the Mediterranean Sea using high resolution gas chromatography high resolution mass spectrometry. Tissues of bluefin tuna (Thunnus thynnus thynnus), swordfish (Xiphias gladius), and common cormorants (Phalacrocorax carbo) collected from the Italian coasts were analyzed for the presence of p,p -DDE, PCBs, PCDDs, PCDFs and PCNs. Barn swallows (Hirundo rustica) collected from agricultural areas in Pianura Padana near Milan, northern Italy, were analyzed for the presence of the target organochlorines. 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) were calculated by multiplying the concentrations of toxic congeners with their corresponding toxic equivalency factors (TEFs) derived from H4IIE in vitro bioassays (7 9). MATERIALS AND METHODS Samples of liver, muscle and fat from sexually mature (fork length > 110 cm) bluefin tuna were collected in Palizzi, southern coast of Italy, during October November Total length and weight of tuna ranged from 149 to 171 cm and 46 to 61 kg, respectively. Liver and muscle were taken from mature swordfish, which were harpooned in Stretto di Messina in the Ionian Tyrrhenian Seas during July Heavy ship traffic is a major source of pollution in the Stretto di Messina. Total length and weight of swordfish ranged from 107 to 190 cm and 15 to 83 kg, respectively. Tissues from several individuals were pooled to obtain representative samples. Livers of cormorants were collected from the birds that were originally sacrificed in 1997 by the Department of Sanitation, Division of Rearing and Zootechnical Resources. Cormorants were collected near Oristano (West coasts of Sardinia Island) in the vicinity of Cabras lagoon in the Sardinian Sea. It is a protected area and is less polluted. Barn swallows were collected during July September 1995 at farms located in Pianura Padana near Milan. Pianura Padana is a large area in northern Italy characterized by intensive farming. The barn swallows collected at the nests were 1 2-years old and were between 165 and 118 g total weight. Tissues were wrapped in clean aluminum foil or whirlpac bags and stored frozen at 20 C until analysis. Sampling locations of fishes and birds are shown in Figure 1. The sampling locations, in general, are background sites with no known point sources of pollution. CHEMICAL ANALYSIS Chloronaphthalene (CN), chlorobiphenyl (CB) and 2,3,7,8-substituted congeners of PCDDs and PCDFs were analyzed follow- Figure 1. Map of Italy showing sampling locations of fishes and birds. 207

2 ing the method described elsewhere (10) with some modifications. Samples were homogenized with sodium sulfate and Soxhlet extracted with methylene chloride and hexane (3:1, 400 ml) for 16 hrs. The extract was rotary evaporated at 40 C and an aliquot was used for the determination of fat content by gravimetry. The remaining extract was spiked with 13 C-TCDD, 13 C-TCDF, 13 C-OCDD and 13 C-OCDF as internal standards and interferences removed by fractionation with multilayer silica gel column. The multilayer silica gel column was prepared by packing a glass column (20 mm i.d.) with a series of layers of silica gel in the following order: 2 g silica, 6 g 40% acidic-silica, 2 g silica and a thin layer of sodium sulfate at the top. The column was cleaned with 150 ml of hexane prior to the transfer of sample extracts. Samples were then eluted with 200 ml of hexane and rotary evaporated to 5 ml. A portion of the aliquot was taken for the analysis of PCB congeners other than non-ortho coplanar PCBs. The remaining samples were passed through a glass column (10 mm i.d.) packed with 1 g silica gel impregnated carbon (Wako Pure Chemical Industries, Tokyo, Japan) for the separation of ortho-substituted PCBs from PCNs and PCDDs/DFs. The first fraction, which was eluted with 150 ml of hexane contained major PCB congeners, which interfere with the analysis of PCNs and PCDDs/DFs. The second fraction, which was eluted with 200 ml of toluene contained non-ortho substituted PCB congeners 77, 126 and 169, PCNs and PCDDs and PCDFs. PCB congeners were identified and quantified using a gas chromatograph (Perkin Elmer series 600) equipped with 63 Ni electron capture detector (GC-ECD). A fused silica capillary column coated with DB-5MS ((5%-phenyl)-methylpolysiloxane, 30 m x 0.25 mm i.d.; J&W Scientific, Folsom, CA, USA) having a film thickness of 0.25 µm was used. PCB congeners were identified against a standard mixture containing 100 congeners of known composition and content. Further details of PCB analysis are reported elsewhere (10, 11). Identification and quantification of individual PCN and PCDD/DF congeners were accomplished with a Hewlett Packard 6890 series high resolution gas chromatograph (HRGC) coupled to a JEOL JMS-700 high resolution mass spectrometer (HRMS). PCN congeners, hepta- and octa-chlorodibenzo-p-dioxins and furans and non-ortho coplanar PCBs were separated using a DB-1701 column. Tetra- through hexa-chlorodibenzo-p-dioxins and furans were separated by a capillary column coated with SP The column oven temperature was programmed from 80 to 160 C at a rate of 40 C min 1 and then to 170 C at 10 C min 1, to 250 C at 4 C min 1 and then to 296 C at 8 C min 1 with a final hold time of 10 min. Injector and transfer line temperatures were held at 260 and 250 C, respectively. Helium was used as the carrier gas. The mass spectrometer was operated at an electron impact (EI) en- ergy of 70 ev. CN and dioxin congeners were determined by selected ion monitoring (SIM) at the 2 most intensive ions of the molecular ion cluster. A mixture of Halowaxes 1001, 1014, and 1051 containing all the tri- through octa-chloronaphthalenes was used as a standard for the quantification of PCNs. PCDD and PCDF congeners were quantified by comparing individually resolved peak areas to the corresponding peak areas of the standards. Recoveries of 13 C-labelled PCDDs/DFs, which elute in the second fraction containing PCNs and non-ortho coplanar PCBs, were 77 95%. Reported concentrations were not corrected for the recoveries of the internal standard. Recoveries of PCB, PCN, PCDD and PCDF congeners through the analytical procedure were between 90 and 100%. Procedural blanks were analyzed throughout the whole analytical procedure to check for interferences. The detection limits of individual PCN and PCB congeners varied depending on the sample masses, response factors and interferences. Generally, detection limits for individual congeners were 1 to 75 pg g 1, on a wet weight basis. Quality control criteria for positive identification of target compounds included signal to noise ratio above 3, isotope ratios of the 2 monitored ions for each compound within 15% of the theoretical chlorine values, and that the compound should elute at the same GC retention time as the standards. CN and CB congeners are represented by using their IUPAC numbers throughout this report (12, 13). RESULTS AND DISCUSSION Bluefin Tuna Concentrations of total PCBs in livers of bluefin tuna ranged from 224 to 1660 ng g 1 (mean: 934; n = 3) on a wet weight basis (w.w.) (Table 1). The 6-fold variation in the concentrations of total PCBs in tuna livers was related to lipid content. Lipidnormalized concentrations of total PCBs in tuna livers were between 5670 and ng g 1. Mean concentrations of total PCBs in tuna muscle and fat were 280 (n = 2) and 817 ng g 1, w.w., respectively. Concentrations of total PCBs in bluefin tuna collected from the Ionian and Tyrrhenian Seas in the late 1970s ranged from 4.7 to 5000 ng g 1, w.w. (14). Similarly, muscle of bluefin tuna collected in 1993 contained total PCB concentrations in the range of 170 to 2200 ng g 1, w.w. (1). Concentrations of total PCBs in tuna muscle analyzed in this study were less than those reported earlier. However, it should be noted that tuna analyzed in this study were smaller (46 to 61 kg) than those analyzed in earlier studies (70 to 400 kg) (1), which could have contributed to the observed temporal differences in total PCB concentrations. Hexachlorobiphenyl no. 153 (2,2',4,4',5,5'-HxCB) was the most predominant congener found in tuna tissues (Table 2). This congener accounted for, on average, 20% of the total PCB concentrations in tuna tissues. In a sample of tuna liver, heptachlorobiphenyl no. 180 (2,2',3,4,4',5,5'-HpCB) accounted for the greatest proportion of total PCB concentrations (Table 2). A few earlier studies have reported the occurrence of elevated proportions of congener 180 in livers and blubbers of striped dolphins from the Italian coast of the Tyrrhenian Sea (2, 3). CB congener 180 accounts for approximately 10% of the total PCBs by weight in Aroclor 1260 (15). This congener accounted for, on average, 10% of the total PCBs in the tissues of tuna. This Table 1. Concentrations (wet weight) of p,p -DDE (ng g 1 ), total PCBs (ng g 1 ) and total PCNs (pg g 1 ) in fishes and birds from Italy. Species Tissue Fat (%) Collection date Location N p,p -DDE PCBs PCNs Tunafish Liver 11.5 Oct Nov 1999 Palizzi NA Tunafish Liver 3.95 Oct Nov 1999 Palizzi Tunafish Liver 10 Oct Nov 1999 Palizzi NA Tunafish Muscle 5.3 Oct Nov 1999 Palizzi Tunafish Muscle 2.92 Oct Nov 1999 Palizzi Tunafish Fat 85 Oct Nov 1999 Palizzi Swordfish Liver 16.2 July 1999 Stretto Messina Swordfish Muscle 8.78 July 1999 Stretto Messina Swordfish Muscle 9.5 July 1999 Stretto Messina Cormorant Liver Cabras lagoon Cormorant Liver Cabras lagoon Cormorant Liver Cabras lagoon Swallow Liver Milan Swallow Liver Milan Swallow Muscle Milan Swallow Muscle Milan N= number of samples pooled. NA= not analyzed. 208 Royal Swedish Academy of Sciences 2002 Ambio Vol. 31 No. 3, May 2002

3 suggests exposure of tuna to highly chlorinated PCB mixtures and/or selective retention of congener 180 in fish tissues. Congener 180 has been shown to be resistant to metabolism by marine animals (16). Overall, hexa- and hepta-chlorobiphenyl congeners 153, 138, 180, and 170, collectively accounted for 35 to 47% of the total PCB concentrations in tuna tissues. Mean concentrations of p,p -DDE in liver, muscle and fat of tuna were 82, 49 and 135 ng g 1, w.w., respectively (Table 1). The observed concentrations of p,p -DDE in the muscle of tuna were less than those reported for relatively larger size tuna collected in 1993 ( ng g 1, w.w.) (1). Polychlorinated naphthalenes were found in all the analyzed tissues of bluefin tuna at concentrations ranging from 7 (muscle) to 550 pg g 1, w.w. (fat) (Table 1). The observed concentrations of PCNs were 3 to 5 orders of magnitude less than total PCB concentrations. Tuna fat contained the highest concentration of PCNs. In this tissue, 17 of the 75 PCN congeners were found. CN congeners 54 (1,2,3,6,7-PeCN), 56 (1,2,3,7,8-PeCN), 66/67 (1,2,3,4,6,7-/1,2,3,5,6,7-HxCNs), 61 (1,2,4,6,8-PeCN) and 52/60 (1,2,3,5,7-/1,2,4,6,7-PeCNs) were the predominant congeners collectively accounting for 84% of the total PCN concentrations in tuna fat. Concentrations of PCNs (1360 pg g 1, lipid weight (l.w.) in tuna livers were greater than those reported for cod livers (388 pg g 1, l.w.) collected in 1998 from the Arctic Ocean (17). However, the observed concentrations of PCNs in livers of tuna from Italy were less (1360 pg g 1, l.w.) than those found in the livers of cod from the Baltic Sea (9800 pg g 1, l.w.) (18). Concentrations of 2,3,7,8-substituted congeners of PCDDs/ DFs were generally less than the limits of detection, which varied from 1 to 75 pg g 1, w.w., depending on the congeners and tissue (Table 3). PCDD/DF congeners that were detected in tuna tissues include, 2,3,4,7,8-PeCDF and 1,2,3,4,7,8-HxCDF, which were found in a sample of tuna fat at concentrations of pg g 1, w.w. Previous studies have not reported concentrations of PCDDs/DFs in tuna from the Italian coast of the Mediterranean Sea. Nevertheless, concentrations of PCDDs/DFs in livers of dolphins from the Mediterranean Sea have been reported to range from 13 to 107 pg g 1, w.w. (19). Swordfish Concentrations of total PCBs in pooled samples of liver and muscle of swordfish were 745 and 329 ng g 1, w.w., respectively (Table 1). Similarly, concentrations of p,p -DDE in swordfish liver and muscle were 135 and 57 ng g 1, w.w., respectively. The observed concentrations of PCBs and p,p -DDE in swordfish tissues were similar to those found in bluefin tuna. Similarly, profiles of PCB congeners in swordfish were similar to those observed for bluefin tuna. Hexachlorobiphenyl congener 153 accounted for the greatest proportion of total PCBs (20%) followed in order by 180 (12%) and 138 (7%) (Table 2). PCNs were also found in swordfish tissues at concentrations of 15 pg g 1, w.w., in muscle and 63 pg g 1, w.w., in liver. Tri-CN congeners 14/16 (1,2,4-/1,4,6-TrCNs) were the most abundant in swordfish. These congeners collectively accounted for 50% of the total PCN concentrations. PCDD/DF congeners were not found in swordfish Table 2. Concentrations of PCB congeners (w.w.) including non- (pg g 1 ), mono- (ng g 1 ) and di-ortho PCBs (ng g 1 ) in tuna, swordfish, cormorant and swallow tissues from Italy. Sample Tissue N Fat (%) Non-ortho PCBs Mono-ortho PCBs Di-ortho PCBs (ng g-1) Total (pool) (pg g 1 ) (ng g 1 ) PCBs * Tunafish Liver < Tunafish Liver < < Tunafish Liver 5 10 NA 293 NA < Tunafish Muscle Tunafish Muscle < Tunafish Fat Swordfish Liver < Swordfish Muscle < Swordfish Muscle < Cormorant Liver < Cormorant Liver Cormorant Liver NA NA NA < Swallow Liver Swallow Liver Swallow Muscle Swallow Muscle N= number of samples pooled. NA= not analyzed. *138 plus 158. Table 3. Concentrations of 2,3,7,8-substituted PCDDs/DFs (pg g 1, w.w.) in fishes and birds from Italy. PCDD congeners PCDF congeners Species Tissue OCDD OCDF Tuna Liver < 2 < 2 < 10 < 10 < 10 < 5 < 50 < 6 NA NA NA NA NA NA < 6 < 6 < 10 Tuna Muscle < 1 < 1 < 2 < 3 < 2 < 3 < 2 < 2 < 2 < < 1.5 < 2 < 3 < 4 < 3 < 2 Tuna Muscle < 3 < 1 < 3 < 4 < 3 < 3 < 2 < 3 < 5 < 6 < 2 < 2 < 10 < 2 < 4 < 4 < 3 Tuna Fat < 40 < 20 < 15 < 25 < 25 < 10 < 7 < 18 < < 5 < 5 < 10 < 12 < 25 < 5 Swordfish Muscle < 1 < 4 < 6 < 6 < 2 < 10 < 4 < 5 < 4 < 4 < 5 < 4 < 4 < 4 < 12 < 14 < 3 Swordfish Muscle < 3 < 2 < 10 < 10 < 10 < 10 < 4 < 6 < 6 < 6 < 5 < 5 < 5 < 5 < 10 < 8 < 6 Swordfish Liver < 10 < 10 < 20 < 20 < 20 < 30 < 30 < 20 < 20 < 20 < 10 < 60 < 10 < 10 < 25 < 25 < 20 Cormorant Liver < 15 < 75 < 10 < 10 < 10 < 5 < 2 < 4 < 2 < 10 < < 4 < 4 < 6 < 8 < 4 Cormorant Liver < 3 < 5 < 8 < 8 < 8 < 30 < 10 < 8 < 3 < 3 < 10 < 10 < 10 < 10 < 30 < 30 < 16 Cormorant Liver < < < 3 < 10 < 6 < 3 < < 5 < 5 < 5 < 6 < 14 < 12 < 8 Swallow Liver < < < 13 < 50 < 25 < < 12 < 15 < 15 < 15 < 15 < 40 < 40 < 25 Swallow Liver < 10 < 10 < < 15 < 6 < 3 < 2 < 1 < 2 < 6 < 6 < 6 < 6 < 20 < 15 < 3 Swallow Muscle < 3 < 3 < 3 < 8 < < 4 < 3 < 4 < 4 < 4 < 4 < 6 Swallow Muscle < < 3 < 10 < 5 < 3 < 5 15 < 4 < 4 < 3 < 3 < 10 < 20 < 6 NA = not analyzed. 209

4 above the limits of detection (Table 3). To our knowledge, reports of organochlorine concentrations in swordfish are not available for comparison. This study provides baseline measurements of organochlorines in swordfish for the first time. Cormorants Concentrations of total PCBs in livers of cormorants ranged between 722 and 2300 ng g 1, w.w. (Table 1). The measured concentrations of PCBs in cormorant livers were comparable to those reported in Germany (2400 ng g 1, w.w.) during 1985/86 (6). However, concentrations of total PCBs in cormorant livers from Italy were less than those reported from Lake Biwa, Japan (6800 ng g 1, w.w.) (20). Hexa-CB congener 153 accounted for 20% of the total PCB concentrations followed by congeners 138 (16%) and 180 (7%). Concentrations of p,p -DDE in cormorant livers ranged from 144 to 190 ng g 1, w.w. (mean: 166 ng g 1, w.w.). Concentrations of PCNs in cormorant livers ranged from 130 to 795 pg g 1, w.w. (mean: 424 pg g 1, w.w.). Mean PCN concentrations in cormorant livers were 7-times greater than those found in the livers of tuna and swordfish. Estimated concentration of total PCNs in livers of cormorants collected from the Baltic Sea was pg g 1, w.w. (21). Concentrations of total PCNs measured in cormorant livers from Cabras lagoon in the Sardinian Sea were approximately 30-fold less than those reported in Baltic Sea cormorants. CN congeners 66/67, 42 (1,3,5,7-TeCN), 61 and 52/60 accounted for 90% of the total PCN concentrations in cormorant livers. As mentioned earlier, CN congeners 66/67, 61 and 52/60 were also abundant in bluefin tuna livers. These congeners have been shown to be strongly bioaccumulative in wildlife (21). PCDD congeners, 1,2,3,7,8- PeCDD and 1,2,3,6,7,8-HxCDD and PCDF congeners 2,3,4,7,8- PeCDF and 1,2,3,6,7,8-HxCDF were detected in livers of certain individual cormorants. Barn Swallows Swallows, particularly, tree swallows, are being widely used as indicators of local contamination because they feed near their nest of emergent aquatic insects (5, 22, 23). Barn swallows are similar to tree swallows in their feeding habits and migratory behavior. Barn swallows collected from agricultural areas near Milan contained remarkable concentrations of PCBs. Mean concentrations of PCBs in liver and muscle of barn swallows were 1230 and 716 ng g 1, w.w., respectively (n = 2). Profiles of relative concentrations of PCB congeners in swallows were similar to those observed for cormorants with PCB congener 153 accounting for the greatest proportion of total PCB concentrations followed in decreasing order by CB congener 138 congener 180. Concentrations of p,p -DDE in the liver and muscle of swallows were 95 and 75 ng g 1, w.w., respectively (Table 1). PCNs were also found in swallows at concentrations ranging from 116 to 215 pg g 1, w.w.. PCN congeners 52/60 and 66/67 were the major congeners in swallow tissues. Among PCDDs/DFs, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 2,3,7,8- TeCDF, 1,2,3,7,8-PeCDF and 2,3,4,7,8-PeCDF were detected in barn swallows (Table 3). Toxic Equivalents To our knowledge, no previous studies have reported on the occurrence of PCNs in biota from the Mediterranean Sea. The results of this study permitted the analysis of the relative contribution of PCNs to total TEQs (sum of TEQs of coplanar PCBs, PCDDs/DFs and PCNs). All PCN congeners are planar and several of them exhibit AhR mediated cytochrome P450 induction, analogous to TCDD (8, 9). Toxic equivalency factors (TEFs) or relative potencies reported for several PCN congeners based on in vitro bioassays using H4IIE rat hepatoma cells were used for calculating TEQs (8, 9, 24). For comparison of TEQs contributed by PCNs, PCBs, PCDDs, and PCDFs, it would be appropriate to use TEFs derived using similar bioassays. For comparison of TEQs contributed by PCNs (PCN-TEQs) with those contributed by PCBs (PCB-TEQs), PCDDs (PCDD-TEQs) and PCDFs (PCDF-TEQs), concentrations of 2,3,7,8-substituted congeners of PCDD and PCDF and non- and mono-ortho-substituted PCBs were multiplied by their corresponding TEFs derived from H4IIE bioassays (7). Di-ortho PCBs were not included in PCB-TEQ estimation. It should be emphasized that the estimation of TEQs is for the examination of relative contribution of PCNs, PCBs and PCDDs/DFs to total TEQ concentrations and not for risk assessment, which would require species-specific TEFs. Calculated concentrations of total TEQs (sum of TEQs of PCBs, PCNs and PCDDs/DFs) in the tissues of tuna ranged from 0.99 to 28 pg g 1, w.w. (Table 4). Total TEQs in swordfish tissues were in the range of 1.47 to 3.55 pg g 1, w.w.. Total TEQs in swallow tissues were greater ( pg g 1, w.w.) than those estimated for cormorant livers ( pg g 1, w.w.). Non- and monoortho PCBs were the major contributors to total TEQ concentrations in fishes (Fig. 2). In particular, non-ortho coplanar PCB Table 4. Estimated concentrations (pg g 1, w.w.) of total TEQs* in fishes and birds from Italy. Species Tissue Total TEQs Tunafish Liver 6.65 Tunafish Liver 10.1 Tunafish Liver 6.76 Tunafish Muscle 2.07 Tunafish Muscle 0.99 Tunafish Fat 28.5 Swordfish Liver 3.55 Swordfish Muscle 1.47 Swordfish Muscle 1.66 Cormorant Liver 9.54 Cormorant Liver 11.9 Cormorant Liver 5.75 Swallow Liver 18.7 Swallow Liver 14.1 Swallow Muscle 19.7 Swallow Muscle 18.8 * Sum of TEQs of PCBs, PCNs and PCDDs/DFs. * For those congeners below the limits of detection, detection limits were used to calculate the TEQs. Figure 2. Relative contribution (%) of PCBs, PCNs and PCDDs/DFs to total TEQ concentrations in tissues of tuna, swordfish, cormorants and swallows. Tuna liver Tuna muscle Tuna fat Swordfish liver Swordfish muscle Cormorant liver Swallow liver Swallow muscle PCBs PCNs Contribution (%) PCDDs/DFs 210 Royal Swedish Academy of Sciences 2002 Ambio Vol. 31 No. 3, May 2002

5 congener 126 accounted for 80 to 90% of the total TEQs in fishes. The contribution of this congener to total TEQs was relatively less in birds accounting for 52 to 76% of the total TEQs. In the livers of cormorants and muscle tissues of swallows, PCDDs/DFs contributed up to 80 and 45%, respectively, of the total TEQs. PCDF congeners 2,3,7,8-TeCDF and 2,3,4,7,8- PeCDF accounted for 60% of the PCDD/DF-TEQs in swallow muscle. In cormorant livers, 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and 1,2,3,6,7,8-HxCDF accounted for 95% of the PCDD/DF- TEQs. The contribution of PCNs to total TEQs in fishes and birds from the Mediterranean Sea was less than 2%. The greatest PCN-TEQ concentration of 0.15 pg g 1 was 1.3% of the total TEQs calculated in the liver of a cormorant. In fishes, PCNs accounted for up to 0.3% of the total TEQs. This is less than what has been reported to occur in earlier studies in which PCNs contributed up to 50% of the total TEQs in fishes from the Detroit River (25). PCN congeners 66/67 accounted for 0.3 to 13% of the total TEQs in fishes from the Baltic Sea (26). Relatively less contribution of PCNs to TEQs in Mediterranean fishes and cormorants suggests less exposure in off-shore species analyzed in this study. Although this calculation gives the relative importance of each organochlorine group to the total contribution of dioxin-like effects, caution should be exercised in assessing the risks since non-detects were assigned a concentration of zero for estimating the TEQs. The limits of detection of certain PCDD/ DF congeners were high. References and Notes 1. Corsolini, S., Focardi, S., Kannan, K., Borrell, A., Tanabe, S. and Tatsukawa, R Congener profile and toxicity assessment of polychlorinated biphenyls in dolphins, shark and tuna collected from Italian coastal waters. Mar. Environ. Res. 40, Marsili, L. and Focardi, S Chlorinated hydrocarbon (HCB, DDTs and PCBs) levels in cetaceans stranded along the Italian coasts: An overview. Environ. Monit. Assess. 45, Reich, S., Jimenez, B., Marsili, L., Hernández, L.M., Schurig, V. and González, M.J Congener specific determination and enantiomeric ratios of chiral polychlorinated biphenyls in striped dolphins (Stenella coeruleoalba) from the Mediterranean Sea. Environ. Sci. Technol. 33, Kannan, K., Blankenship, A.L., Jones, P.D. and Giesy, J.P Toxicity reference values for the toxic effects of polychlorinated biphenyls to aquatic mammals. Hum. Ecol. Risk Assess. 6, Ankley, G.T., Niemi, G.J., Lodge, K.B., Harris, H.J., Beaver, D.L., Tillitt, D.E., Schwartz, T.R., Giesy, J.P., Jones, P.D. and Hagley, C Uptake of planar polychlorinated biphenyls and 2,3,7,8-substituted polychlorinated dibenzofurans and dibenzo-p-dioxins by birds nesting in the lower Fox River and Green Bay, Wisconsin, USA. Arch. Environ. Contam. Toxicol. 24, Scharenberg, W Cormorants (Phalacrocorax carbo sinensis) as bioindicators of polychlorinated biphenyls. Arch. Environ. Contam. 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Technol. 34, Järnberg, U., Asplund, L., de Wit, C., Grafström, A-K., Haglund, P., Jansson, B., Lexén, K., Strandell, M., Olsson, M. and Jonsson, B Polychlorinated biphenyls and polychlorinated naphthalenes in Swedish sediment and biota: Levels, patterns and time trends. Environ. Sci. Technol. 27, We thank Istituto Centrale per la Ricerca Scientifica e Tecnologica Applicata al Mare (ICRAM) for providing samples of tuna fish and sword fish; Prof. Claudio Leonzio (University of Siena) and Istituto Zooprofilattico Sperimentale per la Sardegna, Dipartimento Igiene degli Allevamenti e delle Produzioni Zootecniche for providing tissues of cormorants. We thank Prof. Nicola Saino, University of Milano for providing tissues of barn swallows. 28. First submitted 19 March Accepted for publication after revision August Kurunthachalam Kannan, PhD, is a Visiting Associate Professor at National Food Safety and Toxicology Center in Michigan State University, East Lansing, Michigan, USA. His address: National Food Safety and Toxicology Center, Department of Zoology, Institute for Environmental Toxicology, Michigan State University, East Lansing, MI 48824, USA. kuruntha@msu.edu Simonetta Corsolini, PhD, is a research scientist at Department of Environmental Biology, University of Siena, Italy. Her address: Dipartimento di Scienze Ambientali, Università di Siena, I Siena, Italy. corsolini@unisi.it Takashi Imagawa, PhD, is a senior research scientist at National Institute for Resources and Environment, Tsukuba, Japan. His address: National Institute for Resources and Environment, 16-3 Onogawa, Tsukuba, Ibaraki 305, Japan. Silvano Focardi, PhD, is a professor at Department of Environmental Biology, University of Siena, Italy. His address: Dipartimento di Scienze Ambientali, Università di Siena, I Siena, Italy. John P. Giesy, PhD, is a distinguished professor of Department of Zoology, National Food Safety and Toxicology Center and Institute for Environmental Toxicology at Michigan State University. His address: National Food Safety and Toxicology Center, Department of Zoology, Institute for Environmental Toxicology, Michigan State University, East Lansing, MI 48824, USA. jgiesy@aol.com The research interests of the authors include understanding of environmental distribution, dynamics, fate and effects of trace organic pollutants. 211