K. Kannan, 1 M. Ueda, 2 J. A. Shelby, 3 M. T. Mendonca, 3 M. Kawano, 2 M. Matsuda, 2 T. Wakimoto, 2 J. P. Giesy 1. Materials and Methods

Transcription

1 Arch. Environ. Contam. Toxicol. 38, (2000) DOI: /s ARCHIVES OF Environmental Contamination and Toxicology 2000 Springer-Verlag New York Inc. Polychlorinated Dibenzo-p-Dioxins (PCDDs), Dibenzofurans (PCDFs), Biphenyls (PCBs), and Organochlorine Pesticides in Yellow-Blotched Map Turtle from the Pascagoula River Basin, Mississippi, USA K. Kannan, 1 M. Ueda, 2 J. A. Shelby, 3 M. T. Mendonca, 3 M. Kawano, 2 M. Matsuda, 2 T. Wakimoto, 2 J. P. Giesy National Food Safety and Toxicology Center, Department of Zoology, Institute for Environmental Toxicology, Michigan State University, East Lansing, Michigan 48824, USA 2 Department of Environment Conservation, Ehime University, Tarumi 3-5-7, Matsuyama , Japan 3 Department of Zoology and Wildlife, Auburn University, Auburn, Alabama 36849, USA Received: 4 May 1999/Accepted: 20 September 1999 Abstract. Concentrations of polychlorinated-dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs), -biphenyls (PCBs), and organochlorine pesticides were measured in tissues of map turtles collected from two locations in the Pascagoula River drainage of Mississippi, USA. PCBs were most predominant among the organochlorines with a concentration of up to 99 ng/g, wet weight (580 ng/g, lipid weight) in livers. The greatest concentration of PCDDs/DFs of 1.1 pg/g, wet weight (15.76 pg/g, lipid weight) was found in the liver of a male turtle. The measured concentrations of organochlorines were less than those reported for turtles from the Great Lakes Basin and upper St. Lawrence River. PCBs contributed 90 99% of the total estimated 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs). Particularly, PCB congeners 105, 118, and 156 accounted for 68 80% of the estimated toxic potency of PCBs in turtles. The yellow-blotched map turtle (sawback), Graptemys flavimaculata Cagle, is found only in the Pascagoula River system of southern Mississippi, USA. It is known from the Pascagoula River and its major tributaries, Leaf, Chickasawhay, and Escatawpa Rivers. Due to the rapid decline in the populations, this species is classified as threatened under the Endangered Species Act by the U.S. Fish and Wildlife Service (Seigel and Brauman 1995). The reason for this decline is not known, but high rates of mortality in nests from river flooding, nest predation, and water quality degradation have been suggested as possible causes (Jones 1992; Seigel and Brauman 1995). Reproductive frequency, clutch size, and hatching success of yellow-blotched map turtles were less than those of the other related turtles in Mississippi (Seigel and Brauman 1995). Persistent, bioaccumulative, and toxic contaminants, such as DDTs and polychlorinated biphenyls (PCBs), have been suspected to cause reproductive impairment in certain reptilians, including some turtle species, because of vulnerability of early Correspondence to: K. Kannan life stages (Bergeron et al. 1994; Guillette et al. 1995; Bishop et al. 1998). Red-eared slider turtle eggs (Tachyemys scripta) exposed to certain PCB congeners and their hydroxylated metabolites produced females at male-producing temperatures (Bergeron et al. 1994). Snapping turtles (Chelydra serpentina serpentina) that contained greater concentrations of DDTs and PCBs in eggs had higher rates of abnormalities (poor development and hatching success) than those that contained relatively less concentrations (Bishop et al. 1991). Adult snapping turtles from the Hudson River, New York, have been reported to accumulate several parts per million (ppm) concentrations of PCBs in tissues (Olafsson et al. 1983; Bryan et al. 1987a, 1987b; de Solla et al. 1998). Reports of organochlorine accumulation in yellow-blotched map turtles were not available. In this study, concentrations of PCB congeners, organochlorine (OC) pesticides, polychlorinated dibenzo-p-dioxins (PC- DDs), and polychlorinated dibenzofurans (PCDFs) were measured in liver, muscle, and fat of yellow-blotched map turtles collected from two locations in the Pascagoula River drainage in Mississippi. 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents (TEQs) of PCBs, PCDDs, and PCDFs were estimated to evaluate their relative contribution to toxicity. Materials and Methods Yellow-blotched map turtles were collected under letters of permission from Mississippi State Department of Wildlife, Fisheries and Parks in Hattiesburg and Vancleave, Mississippi (Figure 1), areas that still support relatively large populations (e.g., 2,000 individuals). Turtles were caught in the Pascagoula River basin near Hattiesburg and Vancleave. Turtles were trapped in baskets attached to logs where they were frequently seen basking. Upon capture, turtles were sexed, transferred to the laboratory, and euthanized with Nembutal (45 mg/kg). Animals were frozen at 0 C after sacrifice. Animals were partially thawed and dissected at a later date to collect liver, muscle, and fat tissues. Samples were stored in chemically cleaned jars at 20 C until analysis. Muscle from five animals, liver from six animals, and fat from three animals were taken. Due to the availability of a relatively small mass of fat, samples were pooled for analysis. OC pesticides and PCBs were analyzed in livers of four animals and

2 PCDDs, PCDFs, PCBs, and OC Pesticides in Map Turtles 363 Fig. 1. Map of Mississippi, USA, showing Pascagoula River basin and the sampling locations of yellow-blotched map turtles muscle from a single animal, whereas PCDDs/DFs were analyzed in five livers, four muscle, and one fat samples. Chemical Analysis OC pesticides, PCBs, PCDDs, and PCDFs were analyzed following methods described in detail elsewhere (Nakamura et al. 1993; Kannan et al. 1995; Khim et al. 1999), with some modifications. Sample tissues ( 30 g for muscle and liver, 3 6 g for fat) were homogenized with anhydrous sodium sulfate and Soxhlet extracted with methylene chloride (DCM) and hexane (3:1; 400 ml) for 20 h. Extracts were concentrated using a rotary evaporator at 40 C, and lipid content was measured from an aliquot of the extract by gravimetry. Sample extracts were split to determine PCDDs/PCDFs and the remaining OCs separately. For PCB and OC pesticides analyses, sample extracts were treated with sulfuric acid, passed through activated florisil (10 g; mesh size; Sigma, St. Louis, MO) packed in a glass column (10 mm ID) for cleanup and fractionation. The first fraction eluted with 100 ml of high purity hexane (Burdick and Jackson, Muskegon, MI) contained PCBs, HCB and p,p -DDE. Remaining OC pesticides were eluted in the second fraction using 100 ml 20% DCM in hexane. OC pesticides such as DDTs ( p,p -DDE, p,p -DDD, p,p -DDT), HCHs ( -, -, -isomers), CHLs ( -chlordane, -chlordane, heptachlor epoxide), and HCB and PCBs were 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 0.25 mm ID; J&W Scientific, Folsom, CA] having a film thickness of 0.25 µm was used. The column oven temperature was programmed from 120 C (1 min hold) to 180 C at a rate of 10 C/min (1 min hold) and then to 260 C at a rate of 2 C/min with a final holding time of 12 min. Injector and detector temperatures were kept at 250 C and 300 C, respectively. Helium was used as the carrier gas and nitrogen was the make-up gas. An equivalent mixture of Aroclors 1016, 1242, 1254, and 1260 with known composition and content was used as a standard. Individual PCB congeners were identified using a standard mixture containing 100 PCBs. Concentrations of individually resolved peaks were summed to obtain total PCB concentrations. PCB congeners are referred by Ballschmiter and Zell numbers throughout the manuscript. OC pesticides were quantified from individually resolved peak areas based on the peak areas of standards. Recoveries of PCB congeners and OC pesticides spiked into samples and passed through the analytical procedure were between 85 and 105%. Detection limit for OC pesticides was 0.01 ng/g and for all PCBs was 1.0 ng/g, wet weight.

3 364 K. Kannan et al. Table 1. Concentrations of organochlorine pesticides and polychlorinated biphenyls (ng/g, wet weight) in tissues of female yellow-blotched map turtles Sample No Location Hattiesburg Vancleave Vancleave Vancleave Vancleave Tissue Liver Liver Liver Liver Muscle Fat (%) Total PCBs 99 (580) 32 (130) 33 (130) 15 (310) 7.1 (320) DDTs a 50 (290) 7.7 (31) 11 (42) 4.0 (83) 0.1 ( 4.5) HCHs b 1.0 (5.9) 0.17 (0.68) 0.71 (2.7) 0.49 (10) 0.1 ( 4.5) CHLs c 43 (250) 3.1 (12) 3.2 (12) 3.7 (77) 0.1 ( 4.5) HCB 14 (82) 1.5 (6) 1.8 (6.9) ND d 0.1 ( 4.5) a DDTs p,p -DDE p,p -DDD p,p -DDT b HCHs isomers c CHLs -chlordane -chlordane heptachlor epoxide d ND Not determined Seventeen 13 C-labeled tetra-, penta-, hexa-, hepta-, and octa-cdd and CDF congeners substituted at the 2,3,7,8-positions (Cambridge Isotope Laboratories Inc., MA), were spiked at 500 pg each into hexane extracts prior to sulfuric acid treatment. Extracts were passed through a silica gel packed glass column (Merck, silicagel 60; 3 g) and eluted with 120 ml hexane. The hexane extract was K-D (Kuderna-Danish) concentrated and passed through alumina column (Merck-Alumia oxide, activity grade 1) and eluted with 200 ml hexane as the first fraction, which was discarded. The second fraction eluted with 80 ml of 50% DCM in hexane was K-D concentrated and passed through silica gel impregnated activated carbon column (1 g) (Tsuda et al. 1993). The first fraction eluted with 60 ml 25% DCM in hexane was discarded, and the second fraction eluted with 200 ml toluene was concentrated and analyzed by a high-resolution gas chromatograph interfaced with a high-resolution mass spectrometer (HRGC-HRMS). A Hewlett Packard 5890 series II HRGC connected to a JEOL JMS SX102A HRMS was used for the identification and quantification of individual congeners. Separation of tetra-, penta-, and hexa-chlorinated dibenzo-p-dioxin (CDD) and chlorinated dibenzofuran (CDF) was achieved by a CP-Sil 88 column (Chrompack; 60 m 0.25 mm ID) coated at 0.25 µm film thickness, whereas those of hepta- and octa-cdd and CDF was achieved by a DB-5 column (J&W Scientific; 30 m 0.25 mm ID) coated at 0.2 µm film thickness. The column oven temperature for both CP-Sil and DB-5 columns were held at 100 C for 1 min, and then increased at a rate of 20 C/min to 180 C, held for 1 min, and then increased at a rate of 4 C/min to 240 C. The injection was made splitless. Both injector and transfer line temperatures were held at 250 C. Helium was used as a carrier gas at a flow rate of 1 ml/min. The mass spectrometer conditions were as follows: Ionization mode, EI; electron energy, 70eV. PCDD and PCDF congeners were determined by selected ion monitoring (SIM) at the two most intensive ions of molecular ion cluster. Recoveries of individual PCDD and PCDF congeners varied from 33 to 114%, depending on the sample and congeners. The detection limits of tetra-, penta-, hexa-, hepta-, and octa-cdds and CDFs were 0.008, 0.01, 0.01, 0.02, 0.02 pg/g, lipid weight, respectively. Recovery of internal standards ( 13 C-labeled PCDDs/DFs), on average was, 56%. Reported concentrations were not corrected for the recoveries of internal standard. Procedural blanks were analyzed through the whole procedure to check for interferences and contamination arising from glassware and solvents. Results and Discussion PCBs and OC Pesticides PCBs were the predominant group of OC compounds found in turtle tissues (Table 1). Concentrations of OC pesticides were less than those of PCBs and were found in the order DDTs CHLs HCB HCHs. p,p -DDE and -HCH accounted for greater than 70% of the corresponding total concentrations of DDTs and HCHs. This suggested that these compounds were derived from historical inputs rather than recent inputs. On a wet weight basis, OC concentrations in livers were greater than that in muscle, which could be explained by the differences in the lipid content between liver and muscle. The lipid-normalized concentrations of PCBs in livers varied from 130 to 580 ng/g. Variations in the concentrations of PCBs among individuals may have been related to their age and size. Although age and size of the turtles were not measured in this study, an earlier study showed that the concentrations of OCs in livers of snapping turtles varied with age and size (Hebert et al. 1993). Hepatic concentration of PCBs in turtle from Hattiesburg was two to five times greater than that from Vancleave. However, the number of samples analyzed is small to provide conclusive evidence on the spatial differences in concentrations. No earlier studies have reported the concentrations of PCBs and OC pesticides in yellow-blotched map turtles. Therefore, concentrations measured in map turtle tissues were compared with those reported for snapping turtles, for which considerable information is available (Meyers-Schöne and Walton 1994). Concentrations of PCBs in livers of map turtles were approximately 1,000 times less than those reported for snapping turtle livers from a contaminated site in the Upper Hudson River, New York (Bryan et al. 1987a), and 10 to 100 times less than those of diamondback terrapins (Malaclemys terrapin) from a PCB-contaminated Superfund site in Georgia (Kannan et al. 1998). Nevertheless, total PCB concentrations in map turtle livers were similar to those reported in the flesh of snapping turtles from lakes and rivers in Minnesota (Helwig and Hora 1983). Relatively less accumulation of organochlorines in yellow-blotched map turtles than in snapping turtles may be explained by their food habits. While the diet of snapping turtles consists of fish (33%), amphibians, crustaceans, birds and bird eggs (33%), and plant materials (33%) (Bishop et al. 1994), map turtles feed on insects (50 60%), sponges (35 50%), algae (0 30%), and mollusks (Seigel and Brauman 1994). The pattern of relative concentrations of PCB congeners in turtle tissues was dominated by relatively few higherchlorinated congeners (Figure 2). Hexa- and hepta-chlorobiphe-

4 PCDDs, PCDFs, PCBs, and OC Pesticides in Map Turtles 365 Fig. 2. Relative abundance of PCB isomers and congeners in livers of female turtles collected from Hattiesburg and Vancleave in Pascagoula River Basin. Abundances of individual PCB congener is normalized to the PCB congener 153 (2,2,4,4,5,5 -), which is treated as 100. Abundances are in weight % nyls accounted for 60 71% of the total PCB concentrations (Figure 3). Turtles from Vancleave contained a greater proportion of higher-chlorinated PCB congeners than the one from Hattiesburg. This suggests differences in the sources of PCB exposure to turtles between the two sampling locations. Hexachlorobiphenyl 153 (2,2, 4,4,5,5 ) was the predominant congener in turtle liver, accounting for 14 (Hattiesburg) to 21% (Vancleave) of the total PCB concentrations (Figure 2). PCB congeners 153, 180 (2,2,3,4,4,5,5 ), 118 (2,3,4,4,5), and 138 (2,2,3,4,4,5 ) collectively accounted for 45 50% of the total PCB concentrations in turtle livers. Muscle tissue of a turtle from Vancleave also contained a similar congener distribution to that in liver except for the presence of a greater proportion of congeners 180 (14%) and 170 (13%) than that of 153 (12%) in the total PCB concentrations. These results suggest that turtles were exposed to highly chlorinated PCB mixtures, such as Aroclors 1254 and 1260, or that they metabolize lesschlorinated PCB congeners efficiently (Yawetz et al. 1997). The chlorobiphenyl congeners exhibiting the greatest toxicity toward mammals are isostereomers of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and include non-ortho coplanar PCB congeners 77, 126, and 169 (Tanabe 1988). Mono-orthosubstituted PCB congeners, such as PCB 118, 105, 156, also exhibit similar but weaker toxic responses (Van den Berg et al. 1998). Since these congeners elicit common toxic responses through a common mode of action (Giesy and Kannan 1998), their concentrations are expressed as toxic equivalents to identify those congeners that may pose greater health risks. Toxic equivalents (TEQs) were calculated by multiplying the concentration of each of the toxic congeners by its toxicity equivalency factor (TEF). TEFs for PCB congeners have been derived based on their toxicity relative to TCDD, which is considered the most potent congener. The non-ortho PCB congeners 77, 126, and 169 were not found in turtle livers from Vancleave (Table 2). However, livers of turtles collected from Hattiesburg contained PCB congener 77 at a mean concentration of 100 pg/g, wet weight. Mono- and di-ortho congeners were found in all samples from both Vancleave and Hattiesburg. The estimated TEQs of PCBs in turtle livers from Hattiesburg and Vancleave were 4.4 and 0.71 (range: ) pg/g, wet weight, respectively. When TEQs for congeners 126 and 169 were considered at the limits of Fig. 3. Homolog composition of PCBs in the livers of map turtles from Hattiesburg and Vancleave detection, the upper limits for TEQs in turtles from Hattiesburg and Vancleave were 9.8 and 6 pg/g, wet weight, respectively. PCB congeners 156, 118, and 105 contributed 68 80% of the total TEQs. Similarly, greater contributions of mono-ortho PCB congeners 156, 118, and 105 to the TEQs have been reported in marine mammals (Kannan et al. 1993; Corsolini et al. 1995). These results indicate that congeners 156, 118, and 105 would potentially account for most toxicity to the health of these turtles. PCDDs and PCDFs Concentrations of 17 2,3,7,8-substituted PCDD and PCDF congeners in fat, muscle, and liver of turtles are shown (Table 3). Concentrations of PCDD/DFs in the liver of one female turtle from Vancleave ( pg/g, lipid weight) were three times higher than those found in Hattiesburg (2.0 pg/g, lipid weight). The greatest concentration of PCDDs was found in the liver of a male turtle (15.8 pg/g, lipid weight), which was eight times greater than that found in the livers of female turtles from Hattiesburg. The concentrations of PCDDs and PCDFs were less than those reported for the eggs of snapping turtles from the Great Lakes basin (Bishop et al. 1996) and the upper St. Lawrence River (Ryan et al. 1986).

5 366 K. Kannan et al. Table 2. Concentrations of non-, mono-, and di-ortho coplanar PCBs (pg/g wet weight) and their 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) in livers of female yellow-blotched map turtles Congener Structure TEF b Conc TEQ Conc TEQ PCB Hattiesburg (n 1) Vancleave (n 3) Non-ortho 77 3,3,4, ,3,4,4, ,3,4,4,5, Mono-ortho 105 2,3,3,4, , ( ) c ( ) 118 2,3,4,4, , , (810 2,600) ( ) 156 2,3,3,4,4, , ( ) ( ) 157 2,3,3,4,4, (20 210) ( ) 167 a 2,3,4,4,5, , (360 1,000) ( ) Di-ortho 170 2,2,3,3,4,4, , , (690 1,600) ( ) 180 2,2,3,4,4,5, , , (1,700 4,300) ( ) Total TEQs ( ) a Coelutes with congener 185 b From Van den Berg et al. (1998) c Values in parentheses indicate range Concentrations of PCDDs were greater than that of PCDFs in the liver (Table 3). Concentrations of PCDDs in turtle livers were 7 to 75 times greater than those of PCDFs. Concentrations of PCDFs in turtle muscle were below the limit of detection in all the samples except one, which contained 2,3,7,8-TCDF at 0.40 pg/g, lipid weight. Among various PCDD congeners, OCDD accounted for the greatest proportion of total PCDD concentrations (Figure 4). The compositions of individual PCDD congener to the concentrations of total PCDDs in livers of female turtles from Hattiesburg and Vancleave were different (Figure 4). A higher proportion of OCDD to the total PCDD concentration was found in turtles from Vancleave (68%) than those from Hattiesburg (43%). Nevertheless, the composition of PCDF congeners in the livers of turtles from Vancleave and Hattiesburg was similar. Estimated concentrations of TEQs contributed by PCDD/DF congeners in the livers of turtles from Vancleave and Hattiesburg were and pg/g, lipid weight, respectively (Table 4). PCDDs contributed greater than 90% of the PCDD/DF TEQs in turtle livers. 2,3,7,8-TCDD accounted for 51% of the total TEQs contributed by PCDDs in turtles from Vancleave. The contribution by 2,3,7,8-TCDD to the total TEQs in turtles from Hattiesburg was 29%, which was less than that found in Vancleave. Among PCDF congeners, 1,2,3,7,8-PeCDF contributed to 50% of the TEQs. Despite the presence of great concentrations of OCDD in turtle livers, its contribution to TEQs was insignificant (Figure 4). The lipid-normalized concentrations of TEQs estimated for PCBs in turtle liver from Vancleave and Hattiesburg were 3.8 and 26 pg/g, lipid weight, respectively. Generally, TEQs contributed by PCBs in turtles from Hattiesburg and Vancleave were approximately 10 and 100 times greater than those contributed by PCDDs and PCDFs. Overall, PCBs contributed to 90 99% of the total TEQ concentrations in female turtle livers (Figure 5). The contribution by PCDDs to the total TEQs in turtles was 9.5% in Vancleave samples and 0.8% in Hattiesburg samples. These results suggest greater exposure of turtles collected in Vancleave to PCDD sources than those from Hattiesburg. Health Implications of Turtles The toxicological significance of OC concentrations measured in turtle tissues is difficult to assess because of the lack of toxicity reference doses. Earlier studies have measured OC concentrations in the eggs of turtles, since the early life stages are more susceptible to the toxic effects (Hebert et al. 1993; Bishop et al. 1994, 1996). Studies have suggested a significant correlation between the concentrations of OCs in turtle livers and eggs, indicating that an examination of contaminant levels in liver tissues might also provide information regarding the contaminants in egg (Hebert et al. 1993). Exposure of green sea turtle (Chelonia mydas) eggs to p,p -DDE at concentrations of up to 543 ng/g wet weight, did not alter sex ratio and hatching success (Podreka et al. 1998). Based on the assumption that lipid-normalized concentrations of OCs in turtle eggs would be similar to that found in the liver (Meyers-Schöne and Walton 1994), the measured concentrations of p,p -DDE in map turtles were less than that would affect hatching success and survival rate. Female turtles fast during the nesting season, which may

6 PCDDs, PCDFs, PCBs, and OC Pesticides in Map Turtles 367 Table 3. Concentrations of PCDD/PCDF congeners (pg/g, lipid weight) in tissues of yellow-blotched map turtles Sample 106 & & & , , Location Hattiesburg Hattiesburg Hattiesburg Vancleave Vancleave Vancleave Vancleave Vancleave Vancleave Vancleave Sex Female Female Male Female Female Female Female Female Female Female Tissue Muscle Liver Liver Fat Muscle Liver Muscle Liver Muscle Liver Fat (%) PCDDs 2,3,7,8-TCDD ,2,3,7,8-PeCDD ,2,3,4,7,8-HxCDD ,2,3,6,7,8-HxCDD ,2,3,7,8,9-HxCDD ,2,3,4,6,7,8-HpCDD OCDD Total PCDD Surrogate 1 recovery (%) a PCDFs 2,3,7,8-TCDF ,2,3,7,8-PeCDF ,3,4,7,8-PeCDF ,2,3,4,7,8-HxCDF ,2,3,6,7,8-HxCDF ,2,3,7,8,9-HxCDF ,3,4,6,7,8-HxCDF ,2,3,4,6,7,8-HpCDF ,2,3,4,7,8,9-HpCDF OCDF Total PCDF Surrogate 2 recovery (%) b Total PCDD/PCDF a Surrogate 1 13 C TCDD and 13 C OCDD, respectively b Surrogate 2 13 C TCDF and 13 C OCDF, respectively Fig. 4. Composition of individual PCDD and PCDF congeners to the corresponding total PCDD and PCDF concentrations (top) and TEQs (bottom) in the livers of female map turtles from Vancleave and Hattiesburg in the Pascagoula River basin result in the mobilization of stored lipids and consequently OCs to eggs (Meyers-Schöne and Walton 1994). PCB concentrations in eggs were 10 to 64 times greater than those in the muscle of snapping turtles (Bryan et al. 1987b). The use of fat reserves results in the mobilization and preferential deposition of PCBs into the lipid-rich egg yolks. A few field studies from the Great Lakes St. Lawrence River Basin have correlated greater concentrations of PCBs and other OCs in turtle eggs to poor hatching success and deformities (Bishop et al. 1991, 1996; de Solla et al. 1998). Therefore, measurement of OC concentrations in

7 368 K. Kannan et al. Table 4. 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents (TEQs) of PCDDs and PCDFs (pg/g, lipid weight) in yellow-blotched map turtle tissues Sample TEF a 106 & & & , , Location Hattiesburg Hattiesburg Hattiesburg Vancleave Vancleave Vancleave Vancleave Vancleave Vancleave Vancleave Sex Female Female Male Female Female Female Female Female Female Female Tissue Muscle Liver Liver Fat Muscle Liver Muscle Liver Muscle Liver Fat (%) PCDDs 2,3,7,8-TCDD ,2,3,7,8-PeCDD ,2,3,4,7,8-HxCDD ,2,3,6,7,8-HxCDD ,2,3,7,8,9-HxCDD ,2,3,4,6,7,8-HpCDD OCDD Total PCDD TEQs PCDFs 2,3,7,8-TCDF ,2,3,7,8-PeCDF ,3,4,7,8-PeCDF ,2,3,4,7,8-HxCDF ,2,3,4,6,7,8-HpCDF Total PCDF TEQs Total PCDD/PCDF TEQs a From Van den Berg et al. (1998)

8 PCDDs, PCDFs, PCBs, and OC Pesticides in Map Turtles 369 Fig. 5. Contribution (%) by PCBs, PCDDs, and PCDFs to the total TEQs in livers of map turtles from Vancleave and Hattiesburg in the Pascagoula River basin (contribution by PCDFs to the TEQs was insignificant) eggs of yellow-blotched map turtles is needed. The concentrations of OCs measured in tissues of map turtles were lower than those found in field studies that reported poor hatching success and survival rates in snapping turtles. However, a recent study has suggested that the exposure of eggs of red-eared slider turtle (Trachemys scripta elegans) to OC pesticides and PCBs in concert with one another produced significant sex reversal compared to those that were incubated with a single OC compound, suggesting the potential for interactive effects of several OCs (Willingham and Crews 1999). Acknowledgments. 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