Environmental contaminants in tissues of a neonate St Lawrence Beluga Whale (Delphinapterus leucas)

Marine Pollution Bulletin, Vol. 36, No. 1, pp. I02-108, 1998

Pergamon PII: S0025-326X(98)00163-X

© 1998 Published by Elsevier Science Ltd All rights reserved. Printed in Great Britain 0025-326X/98 $19.00+0.00

Environmental Contaminants in Tissues of a Neonate St Lawrence Beluga Whale (Delphinapterus leucas) J. M. GAUTHIER*[I, 1~. PELLETIERt, C. BROCHU:~, S. MOORE~, C. D. METCALFE* and P. B]~LAND§

*Trent University, Environmental and Resources Studies Program, Peterborough, Ontario, K9J 7B8, Canada tlnstitut National de Recherche Scientifique (INRS-Ocdanologie), 310 avenue des Ursulines, Rimouski, QuObec, G5L 3A1, Canada ~Ministdre de l'Environement du Quebec, Direction des Laboratoires, 850 Boul. Vanier, St. Vincent-de-Paul, Laval, Qudbec, H7C 2M7, Canada §lnstitut National d'/?cotoxicologie du St-Laurent, 460 Champ-de-Mars, MontrOal, Qudbec, 1t2 Y 1B4, Canada

Tissue samples of brain, kidney, fiver, and blubber from a neonate St Lawrence beluga whale were analyzed for ortho and non-ortho polychlorinated (PCB) congeners, organochlorine (OC) compounds, polychlorinated dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs), and total mercury. As T-globulins, which indicate presence of colostrum, were not found in serum of the live neonate, it was unlikely that there had been lactational transfer of environmental contaminants to the neonate. No PCDFs were detected. Of the P C D D congeners, only O C D D was found in all tissues; ranging from 12 pg g - ~ lipid in brain to 1138 pg g - i in liver. Concentrations of EPCB (sum of 25 ortho and 4 non-ortho PCBs) and EDDT were lowest in brain (1.7 and 0.7 pg g - 1 lipid, respectively), intermediate in kidney (4.1 and 2.3 pg g - l ) and highest in liver (8.8 and 3.5 pg g - l ) and blubber 117.6 and 2.2 lag g - l ) . PCB 126 was the predominant non-ortho congener. Toxic equivalent 2,3,7,8-TCDD concentrations (TEQs) (pg g i lipid) were: mono-ortho PCBs > nonortho PCBs > P C D D s . Major individual OC compounds were DDE, HCB, oxychlordane and cisnonachior. Similar PCB and OC patterns were found for different tissues, with the exception of ~-HCH in brain. Total mercury was detected in liver, kidney and brain at concentrations of 49-145 ng g - ' (wet weight). Concentrations of PCBs, OCs, and mercury in the neonate were lower than or in the lower range of those found in published data on female adult beluga whales of the St Lawrence, and this is probably due to absence of lactational transfer of contaminants in the neonate. Proportions of lower chlorinated PCBs, HCB, and HCH compounds were greater in the neonate than in these female whales, which may indicate preferen-

JlTo whom correspondence should be addressed. Current address: D6partement des Sciences Biologiques, Universit6 du Qu6bec A Montreal, Montr6al, Qu6bec, H3C 3P8, Canada, e-mail: c2656@er. uqam.ca. 102

tial gestational transfer of these compounds. © 1958 Elsevier Science Ltd. All rights reserved Keywords: Polychlorinated biphenyls (PCBs); organochlorines (OCs); polychlorinated dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs); mercury; beluga; neonate; St Lawrence estuary; gestational transfer.

Beluga whales (Delphinapterus leucas) of the St Lawrence estuary form a small, stable, geographically isolated and endangered population of about 450-700 animals (Michaud, 1993; Kingsley, 1996). This population is highly contaminated with environmental contaminants, which include polychlorinated biphenyls (PCB), DDT, mirex, and mercury (Martineau et al., 1987; Muir et al., 1990, 1996; Wagemann et al., 1990; B~land et al., 1992). A neonate beluga whale found alone and weak in a bay of the St lawrence estuary on August 20, 1991 was brought to the Aquarium de Qu6bec in Qu6bec city for rehabilitation attempt. The animal was 1.55 m in length and weighed 60 kg, which corresponds to a newborn or a slightly premature beluga. Blood samples were taken regularly and the animal was necropsied at death, 10 days after it was brought to the aquarium. Necropsy revealed the cause of death to be neonatal pulmonary atelectasis (DeGuise et al., submitted). Because 7globulins, which indicate presence of colostrum, were not found in serum of the neonate (DeGuise et al., submitted), it is unlikely that there was lactational transfer of environmental contaminants to the neonate. Analysis of individual ortho and non-ortho PCB congeners, organochlorine compounds, polychlorinated-p-dioxin and -dibenzofuran (PCDD/F) congeners and total mercury are reported in this study. Tissue distribution and comparisons between this neonate and

Volume 36/Number 1/January 1998 published data on adult females of the St Lawrence population are given.

Materials and Methods Samples of brain, kidney, liver, and blubber were taken immediately after death, placed separately in solvent-washed glass jars and frozen at - 2 0 °C until analysis. Contaminant analysis PCB and PCDD/F congeners, OC compounds, and total mercury were analysed in all tissues, with the exception of non-ortho PCBs in liver. Procedures for preparation of samples for analysis of ortho and nonortho PCB and PCDD/F congeners were similar to those previously described by Brochu et al. (1995). Samples of 0.2 g of blubber and 10 g of each organ were spiked with a mixture of 13C12 labelled ortho-substituted PCB congeners and PCDD/F congeners and extracted with hexane:methylene chloride 50:50 in a glass column. Ortho-substituted PCBs were fractionated from nonortho PCBs and PCDD/Fs on a alumina column. Further clean-up of the non-ortho PCBs and PCDD/F fraction was done on a AX-21 carbon column. Seven PCDD congeners (2,3,7,8-T4CDD, 1,2,3,7,8PsCDD, 1,2,3,4,7,8-H6CDD, 1,2,3,6,7,8-H6CDD, 1,2,3,4,7,8,9-HTCDD, 1,2,3,4,6,7,8-HTCDD and OsCDD), ten PCDF congeners (2,3,7,8-TaCDF, 1,2,3,7,8-PsCDF, 2,3,4,7,8-PsCDF, 1,2,3,4,7,8-H6CDF, 1,2,3,6,7,8-H6CDF, 2,3,4,6,7,8-H6CDF, 1,2,3,7,8,9H6CDF, 1,2,3,4,6,7,8-H7CDF, 1,2,3,4,7,8,9-H7CDF and OsCDF), and non-ortho PCB congeners 77, 126 and 169 were analysed by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) as described previously (Brochu et al., 1995). Identification of PCDD/Fs and non-ortho PCBs was based on chlorine isotope ratio and retention time. Results were corrected for recovery rates of the 13C12surrogates (60-110%). Detection limits (LOD) for PCDD/Fs and non-ortho PCBs were 0.1~).7 pg g-1 for organs and 0.2-6 pg g-1 for blubber. Ortho substituted PCBs were analysed by HRGC/Iow resolution (LR) MS on a Varian 3400 interfaced to an ion trap detector Saturn II with a 3 0 m × 0 . 2 5 m m O.D. DB5-MS capillary column and a cool on-column injector. Twenty five ortho PCB congeners [52, 44, 101/(90), 87/ (115), 151/(82), 118/(123/149), 114/(131), 153, 105/(132), 141/(179), 138/(160/158), 156/202/171, 187/(182), 183, 128, 185, 201/(173/157), 180, 191, 170/(190), 199, 195/ (208), and 194] were quantified against the CLB-1 standard purchased from the National Research Council, Halifax, Canada. Co-eluting congeners in brackets were quantified but not used in the study. Congeners 82, 149, 131, 132, 179, 202 and 171, 173 and 157, and 208 were separated respectively from 151, 118, 114, 105, 141, 156, 201, and 195 due to differences in molecular weight. The amount of co-eluting conge-

ners 90, 115, 123, 132, 160 and 158, 182 and 190 were considered minor (8-25% of co-eluting congener cluster) in comparison to congeners 101, 87, 118, 153, 138, 187 and 170, respectively. Recovery rates of the 13C12 surrogates for ortho PCBs were between 89-120% and results were not corrected for recovery rates. LODs for ortho PCBs were 0.2-0.3 ng g-1 for organs and 5-8 ng g-1 for blubber. Procedures for preparation of blubber and organ samples for analysis of OCs were similar to those described by Janz et al. (1992). Briefly, samples of 0.5 g of blubber and 1 g of each organ were extracted with hexane in a Soxhlet apparatus and lipids were removed from the extracts by gel permeation chromatography (GPC) on Biobeads SX-3. Lipid content of the sample was estimated by gravimetric analysis of the hexane extractable lipid fraction from the GPC column. OC pesticides were fractionated from PCBs by silica-gel column chromatography. OC compounds were analysed by HRGC equipped with an electron capture detector (ECD) using a Varian model 3500 GC with a 30 mx0.25 mm fused-silica DB-5 column and splitless injection, as described previously (Janz et al., 1992). Quantification of other OC compounds was done by comparison with standards obtained from the Canadian Wildlife Service, Hull, Qu6bec. LODs for OC compounds were between 0.3-1.2 ng g - l . Extraction efficiencies for all analytes were determined to be > 85% by analysis of spiked samples. Total mercury was determined as described by Hodson et al. (1992). Briefly, tissues were digested in nitric and sulphuric acid and total mercury determined using a Fisher HG-3 flameless atomic absorption spectrophotometer (AAS). LOD was 5 ng g - l . Data manipulation Concentrations of chlorinated organic compounds were lipid-normalized (ng g - t lipid) and concentrations of total mercury are reported on a wet weight basis. EPCB was calculated as the sum of analysed congeners. Relative proportions (%) of each PCB congener was calculated as the concentration of the congener to the sum of analysed PCB congeners. IEPCDD and EPCDF were calculated as the sum of analysed PCDD and PCDF congeners, respectively. EDDT was calculated as the sum of the concentrations of DDT, DDD, and DDE. Ychlordane was calculated as the sum of transchlordane, cis-chlordane, trans-nonachlor, cis-nonachlor and oxychlordane, and YHCH as the sum of the four HCH isomers. Relative proportions (%) of the individual compounds within each of these pesticide classes were also determined. Concentrations of HCB, mirex, and total mercury are presented individually.

Results and Discussion Total lipid contents in blubber and organs of the neonate beluga whale were within the range of those 103

Marine Pollution Bulletin TABLE 1

Concentrations of ~PCB and OC compounds (ng g- l lipid) in body tissues of a St Lawrence neonate beluga whale. Data from Muir (pers. comm.) for the mean concentrations (ng g-1 lipid) and concentration range (in parentheses) of EPCB and OC compounds in blubber of adult female St Lawrence beluga whales of reproductive age (6-20 yr) (n = 8) are included for comparison. Neonate OC compound

brain

kidney

liver

blubber

Adult females blubber

lipid (%) EPCB HCB ct-HCH 13-HCH "/-HCH 6-HCH EHCH oxychlordane trans-chlordane cis-chlordane trans-nonachlor cis-nonachlor E chlordane DDE DDD DDT EDDT mirex

6.0 1679 156 195 ND 16 ND 211 91 ND 24 20 64 200 689 ND 13 702 31

1.6 4134 438 37 74 70 ND 182 377 ND 58 148 229 812 2289 ND 43 2332 63

2.4 8779 672 66 74 73 24 237 546 ND 123 340 499 1507 3370 15 82 3467 104

79.2 17 563 279 72 51 34 2 159 365 ND 116 390 492 1362 2106 17 108 2230 57

93.6 (83-100) 23 913 (7689-49051)* 471 (106-1516) 126 (91-167) 111 (33-350) 50 (33-79) NA 287 (176--475) 899 (189-2584) 82 (39-137) 193 (119-275) 2894 (1129-8051) 532 (90-1223) 4600 (1988-12270) 15082 (3288-37 523) 4609 (894--13625) 6666 (1651-20292) 26358 (5254-67405) 990 (185-2419)

ND: not detected, NA: not available. *calculated using 24 PCB congeners analysed in femalesthat were also analysed in the neonate (congener 202 was not analysed in females, but contributed to only 0.09% of EPCB in the neonate).

reported for belugas (Martineau et al., 1987; Muir et al., 1996; Paterson et aL, in preparation), and for other odontocete species (Duinker et al., 1989). Concentrations o f YPCB (sum of 25 ortho- and 4 non-ortho substituted congeners) and other OC compounds in tissues of the neonate beluga are presented in Table 1. Concentrations of EPCB were lowest in brain (1.7 lag g - l lipid), intermediate in kidney (4.1 lag g - l ) , and highest in the liver (8.8 lag g - t ) and blubber (17.6 lag g - t ) . Concentrations of ~ D D T in kidney, liver, and blubber tissue of the neonate ranged between 2.3-3.5 lag g - ~ lipid, which was a b o u t 3-5 times greater than concentrations in the brain (0.7 lag g - l lipid) (Table 1). Other major OC compounds included HCB, oxychlordane, cis-nonachlor and trans-nonachlor (Table 1). With the exception of ~ - H C H , lipid-normalized concentrations of OCs were lowest in brain tissue. Inter-tissue differences in OC concentrations in this neonate were similar to those reported in adult beluga whales and other odontocete species (Tanabe et al., 1981; Mass6 et al., 1986; Duinker et al., 1989; Paterson et al., in preparation). Pharmacokinetic studies have shown that the distribution o f lipophilic contaminants in different tissues reaches equilibrium rapidly and that concentration in each tissue at equilibrium is principally determined by lipid content (Matthews, 1983; Clark et al., 1987). Remaining variations between tissues have been attributed to differential lipid composition, blood flow rate, and metabolic capacities between tissues (Mass~ et al., 1986; Jenssen et al., 1996; Paterson et al., in preparation). 104

Major PCBs in all tissues were congeners 52, I01, 151, 118, 153, 138, 187 and 180; comprising about 85% of EPCB. These PCB patterns were similar in all tissues (Fig. 1), which is consistent with results reported for beluga whales and other marine m a m m a l s (Mass6 et al., 1986; Duinker et al., 1989; Boon et al., 1994; Paterson et al., in preparation). Proportions of D D T compounds were very similar between tissues. D D E comprised over 90% of E D D T in all tissues, which is similar to results reported by Mass~ et al. (1986) and Paterson et al. (in preparation), but higher than reported by Martineau et al. (1987) and Muir et al. (1990, 1996) (mean = 5 2 % for organs, = 60% for blubber, and range = 17-80% for all tissues). Oxychlordane, cis- and trans-nonachlor were the predominant chlordane compounds in all tissues. Contrary to the organs, blubber had the greatest p~oportion-s of trans-nonachlor and the lowest proportions of oxychlordane. Greater proportions of trans-nonachlor (50-60%) and lower proportions of oxychlordane (18-20%) and cis-nonachlor (10-15%) were found in blubber of adult St Lawrence beluga whales (Muir et al., 1996). The a - H C H and I3-HCH were present in similar proportions in all tissues, with the exception of the brain where ~ - H C H comprised over 90% of the H C H compounds. This value is within the range reported for adult beluga whales, other species of odontocetes, and seals (73-91%) (Tanabe et al., 1981; Duinker et al., 1989; M6ssner et al., 1992; Paterson et al., in preparation). Variations in proportions of ¢~-HCH in brain between these studies m a y be due to differences

V o l u m e 3 6 / N u m b e r 1/January 1998 30

25 ¢¢1

20

..

10

~

5

52

101

151

llS

153

lSS

187

lSO

PCB congener • brain • kidney • liver !~blubber [ Fig. 1 Relative proportion of major analysed PCB congeners to ~-PCB in brain kidney, liver, and blubber of a St Lawrence beluga whale neonate.

between species or lipid extraction methods. Higher concentrations of the more hydrophilic ot-HCH and lower concentrations of the more hydrophobic PCB and OC compounds in the brain may be due to the high proportion of polar lipids in brain tissue (Kawai et al., 1988). Non-ortho PCB congeners were analysed in brain, kidney, and blubber. PCB 77 was not detected in any of the tissues. PCB 126 was detected in kidney and blubber at 505 and 166 pg g-1 lipid, respectively, and PCB 169 was detected in brain only at 12 pg g-1 lipid. Contrary to these data, non-ortho PCBs 77 and 169 have been detected in the blubber of female beluga whales (Muir et al., 1996). PCB 126 was the most prominent non-ortho congener in these adult female beluga whales at concentrations between 682-4952 pg g-1 lipid (Muir et al., 1996); 1.4-10 times higher than in this beluga neonate. No PCDFs and only 1,2,3,4,6,7,8-HTCDD and OCDD congeners were detected in tissues of the neonate beluga whale. 1,2,3,4,6,7,8-HTCDD was found at low concentrations (29-31 pg g-1 lipid) in kidney and liver only, and OCDD was found in all tissues. Highest concentrations of OCDD were found in liver (1138 pg g - t lipid) and kidney (227 pg g-l), the lowest were detected in blubber ( 1 8 p g g - l ) and brain (12 pg g-l). Concentrations of OCDD in blubber of adult female beluga whales of the St Lawrence (< 314 pg g - i lipid) were simlar to or lower than in tissues from this neonate (Norstrom and Simon, 1990). In contrast to the neonate, no PCDDs were detected in the liver of these female whales and concentrations of

1,2,3,4,6,7,8-H7CDD and PCDF congeners in blubber were between 1 and 7 pg g-1 lipid (Norstrom and Simon, 1990; Muir et al., 1996). Toxic equivalent 2,3,7,8-TCDD concentrations (TEQs) in the neonate beluga tissues were calculated on a pg g - 1 lipid basis using the toxic equivalent factors (TEFs) published by NATO (1988) for PCDDs and by Ahlborg et al. (1994) for non- and mono-ortho PCB congeners (Table 2). PCDDs, non-ortho PCBs, and mono-ortho PCB congeners contributed between 0.0081.1%, 0.5-32% and 67-99%, respectively, to the ETEQ in tissues of the neonate. Lipid normalized Y.TEQs varied 2- to 10-fold between tissues and were greatest in blubber and liver. The contribution to the ETEQ by non-ortho PCB congeners was greatest in blubber, intermediate in kidney, and lowest in brain. Differences in TEQ values between tissues may have implications on potential for toxic effects of these compounds. The ratio between the ETEQ contributed by mono-ortho PCBs and non-ortho PCBs in blubber was greater in the neonate (5) than the ratio calculated for female adult whales (0.8) from data published by Muir et al. (1996) (see Table 2). Total mercury was detected in brain (49 ng g-1 wet weight), kidney (83 ng g - l ) and liver (145 ng g-l), but not blubber of the neonate. Concentrations in the liver were in a similar range to those found in the liver of three other St Lawrence beluga whale neonates (38, 70 and 310 ng g - t wet weight) (B61and et al., 1992; Wagemann, pers. comm.). Concentrations of EPCB and EDDT in blubber of the neonate were similar or higher than those found in 105

Marine Pollution Bulletin TABLE 2 Toxi~ equivalent 2,3,7,8-TCDD concentrations (TEQs) (lag g - l lipid) of PCDDs, non- and mono-ortho PCB congeners in tissues of a newborn beluga whale. TEQs in blubber of adult (16--31 yr old) female beluga whales (n = 5) were calculated using data published by Norstrom and Simon (1990) and Muir et al. (1996) and are included for comparison.

TEQ (pg g-~ lipid) Neonate

Adult females blubber

Compound

TEF*

brain

kidney

liver

blubber

1,2,3,4,6,7,8-HpCDD OCDD ZPCDD 77 126

0.01 0.001 0.0005 0.1

ND 0.012 0.012 ND ND

169 Y, non-ortho

0.01

0.12

0.31 0.23 0.54 ND 16.6 ND

0.29 !.14 1.43 NA NA NA

ND 0.018 0.018 ND 50.5 ND

0.12 15

16.6 27

NA 74

2.5

6.4 1.5

23

40

6.8

30

34

113 25 1.3

24 24.1

35 52.1

130 131.4

200 240.0

139 317.5

PCBs 118 105 156 Zmono-ortho

PCBs ETEQs

0.0001 0.0001

0.001

40 130

0.038 0.0076 0.046 0.29 176.4 1.75

178.4

TEQ (pg g-1 lipid)= concentration (lag g - l lipid)xtoxic equivalence factor (TEF)* *: Source: NATO (1988) for PCDD/F congeners and WHO/IPCS (Ahlborg et al., 1994) for PCB congeners. ND: not detected, NA: not analysed.

two other St Lawrence beluga whale neonates (PCBs = 5.7 and 6.2 and ZDDT = 1.2 and 2.5 lag g I wet weight) (Martineau et al., 1987; Muir et al., 1996). These differences could be due to different ages and reproductive histories of the respective mothers. No data are available on contaminant concentrations in the mother of the neonate of this study. However, some inferences can be made from published data on adult female St Lawrence beluga whales of reproductive age, that is 6-20 yr (Burns and Seamans, 1985). Concentrations of total mercury measured in the liver of 21 female whales of reproductive age (2.7-207 p.g g - l wet weight) are several folds higher than in liver of the neonate (B61and et al., 1992; Wagemann, pers. comm.). Concentrations of ZPCB and ZDDT in liver of the neonate were in the lower range of concentrations found in liver (PCBs = 6505 and YDDT=2.2-9.8 pg g - l lipid) and kidney (PCBs=5-22 and EDDT=2-4.3 p g g - i lipid) of 3 females of reproductive age (Martineau et al., 1987). Concentrations of EPCB, DDT, chlordane, and HCH compounds and mirex in the blubber of the neonate were lower or in the lower range of concentrations found in the blubber of adult female St Lawrence beluga whales of reproductive age (6-20 yr) (Table 1) (Martineau et al., 1987; Muir, pers. comm.). Relatively low concentrations in the neonate whale may be explained by the lack of lactational transfer. Since no ?-globulins were found in serum of the neonate when first found alive, it was unlikely that it had received colostrum, and therefore milk, through nursing (DeGuise et aL, submitted). The condition of the animal when found, alone and weak and probably slightly premature, suggests that the mother may have died 106

while giving birth, or shortly thereafter, as has been previously observed (B61and et al., 1992). Thus, OCs were only transferred via the placenta during gestation. Striped female dolphins (Stenella doeruleoalba) transfer 79 to 91% of their OC load through lactation, but only 4 to 9% during gestation '(Tanabe et al., 1982). Ratios of HCB, ZHCH, Z~hlordane, ZDDT, and mirex concentrations in the neonate to mean concentrations in female adult beluga whales of reproductive age were 0.59, 0.55, 0.30, 0.08 and 0.06 (see Table 1), perhaps indicating a higher transplacental transfer of HCB, and HCH compounds. The lower and moderately chlorinated tetra- and penta-CB congeners were found in higher proportions and the higher chlorinated hepta- and octa-CBs in lower proportions in "the neonate compared to adult females (Fig. 2). Although differences between the neonate and female whales are small for the lower chlorinated PCBs, this reflects the absence of tri-CBs and the small number of tetra- and penta-CBs analysed in the neonate. Preliminary analysis show that when three tri-CBs, four tetra-CBs and sex penta-CBs were analysed in the neonate, proportions of these homologue groups were 2-3 times greater than in the female whales (data not shown). Studies on the transfer of PCB congeners and OC compounds between pregnant female odontocetes and their foetus have shown that tri-, tetra- and penta-CBs, HCB and HCH compounds are more readily transferred from female blubber to the placenta than the higher molecular weight and more lipophilic hexa-, hepta- and octa-CBs, DDT, and mirex (Tanabe et al., 1982; Subramanian et al., 1988). Transfer OC compounds from maternal blubber to the placenta via the

Volume 36/Number 1/January 1998 60

50 40 o o

30

L~ O

20

o

0 tetra-CB

penta-CB

hexa-CB

hepta-CB

octa=CB

PCB homologue group

[Q neonate [] adult females ] Fig. 2 Relative proportions of PCB homologue groups in the neonate and in adult females St Lawrence beluga whales of reproductive age ( n = 8 ) (Muir, pers. comm.). Female beluga data was calculated using 24 PCB congeners analysed in females that were also analysed in the neonate (congener 202 was not analysed in females, but contributed to only 0.09°/. of ZPCB in the neonate).

blood depend on equilibrium partitioning between these tissues. Blubber is rich in non-polar triglyceride lipids, while polar phospholipids are important constituents of the lipids in blood and placenta (Kawai et al., 1988). Thus, contaminants with high molecular weights and high lipid solubility may be tranferred less readily to the more polar lipids of the blood serum, and thus to the foetus via the placenta (Tanabe et al., 1982; Addison and Brodie, 1987). In conclusion, lipid-normalized concentrations of ZPCB and most OC compounds were highest in liver and blubber, intermediate in kidney, and lowest in brain and patterns were similar between tissues. However, brain had the greatest concentrations of a-HCH, probably due to the differential lipid composition of this tissue. Differential lipid composition, along with differences in blood flow rate and metabolic capacities between tissues, may explain differences in concentrations of analysed compounds between tissues. Presence of PCBs, OCs, PCDD, and mercury in tissues of the neonate, the lower concentrations of most analysed contaminants and the higher proportions of low to moderately chlorinated PCBs, HCH, and HCB compounds in the neonate versus adult female whales seem to demonstrate selective transplacental transfer of environmental contaminants in beluga whales. We thank the Canadian Department of Fisheries and Oceans and the Aquarium de Qurbec for contributing equipment, time, and personnel or funds for the rescue and rehabilitation attempt of the neonate. We are grateful to S. Deguise, J. Giard, R. Michaud, D. Lefebvre, and others who cared for and took blood samples of the neonate. We are especially indebted to D. Muir and R. Wagemann for kindly providing

female beluga data. Special thanks to D. Muir and B. Hickie for helpful review of the manuscript. This work was supported by an Operating Grant to E. Pelletier from the National Science and Engineering Research Council (NSERC) of Canada, by a research grant to C. D. Metcalfe from the Science Subvention fund of the Canadian Department of Fisheries and Oceans, and from an Operating Grant to CDM from the NSERC of Canada. Graduate support for J. M. Gauthier was supplied by Fonds pour la Formation de Chercheuses et Chercheurs et rAide ~t la Recherche (FCAR), Qurbec.

Addison, R. F. and Brodie, P. F. (1987) Transfer of organochlorine residues from blubber through the circulatory system to milk in the lactating grey seal Halichoerus grypus. Canadian Journal of Fisheries and Aquatic Sciences 44, 782-786. Ahlborg, U. G., Beking, G. C., Birnbaum, L. S., Brouwer, A., Derks, H. J. G. M., Feeley, M., Golor, G., Handberg, A., Larsen, J. C., Liem, A. K. D., Safe, S. H., Schlatter, C., Waern, F., Younes, M. and Yrj~inheikki, E. (1994) Toxic equivalent factors for dioxin-like PCBs. Report on a WHO-ECEH and IPCS consultation, December 1993. Chemosphere 28, 1049-1067. Brland, P., Deguise, S. and Plante, R. (1992) Toxicology and pathology of St Lawrence marine mammals. Final report for the World Wildlife Fund's Wildlife Toxicology Fund, 95 pp. Boon, J. P., Oostingh, I., van der Meer, J., Theo, M. and Hillebrand, J. (1994) A model for the bioaccumulation of chlorobiphenyl congeners in marine mammals. Environmental Journal of Pharmacology 270, 237-251. Brochu, C., Hamelin, G., Moore, S., Lalibertr, D. and de la Fontaine, Y. (1995) Contribution of PCDD/PCDFs, planar and ortho substituted PCB congeners to the total TCDD-equivalent concentration in fish fillet from the St Lawrence river. Organohalogen Compounds 26, 293-298. Burns, J. J. and Seaman, G. A. (1985) Investigations of Belukha whales in coastal waters of western and northern Alaska. II.Biology and ecology. Report to the Alaska Dept. of Fish and Game, Fairbanks, Alaska, NA 81 RAC 00049. Clark, T. P., Norstrom, R. J., Fox, G. A. and Won, H. T. (1987) Dynamics of organochlorine compounds in herring gulls (Larus

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