USGS



BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES

Polar Bear

 

Photo of Polar Bear

 



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Biological Characteristics

Species

Ursus maritimus is a one of three North American species in the Family Ursidae. Compared to the black bear (U. americanus) and the brown bear (U. arctos), the polar bear has an elongated neck and comparatively smaller head, with a stocky body that lacks a shoulder hump. Polar bears are completely furred except for the tip of the nose, which is black along with the skin and the lips (Manning, 1971). Polar bear fur appears white when it is clean and in even sunlight, although it is without pigment (DeMaster and Stirling, 1981). At birth, polar bears weigh approximately 600 grams (Blix and Lentfer, 1979), but continue to grow rapidly, with adult males weighing from 300 to 800 kilograms and reaching 2.5 meters in length from the tip of the nose to the tail. Adult female polar bears are comparably smaller, weighing 150 to 300 kg and measuring 1.8 to 2 meters in length (DeMaster and Stirling, 1981).

Status in Estuarine and Coastal Areas

The polar bear is the apical predator of the Arctic marine ecosystem, and their preferred habitat is the pack ice of the Arctic Ocean, where the ice edge and pressure ridges provide the best hunting grounds. As the ice melts and refreezes, polar bears will travel as much as 1,000 km north and south. In the summer, bears will be found on islands or coastlines that have landfast ice, or they will drift on ice flows (DeMaster and Stirling, 1981). Pregnant female polar bears make their dens in snow and ice in early winter usually within 8 km of the coast. Polar bears are sequentially polygynous, with the male and female only remaining a pair for about three days while the female is in estrus. Mating occurs from March to June, and an average of two young (range from 1 to 4) is born between November and January. Cubs stay in the dens until April when they can survive the outside climate. Female polar bears may produce up to five litters in their lifetime. Cubs are altricial and will stay with their mothers until the spring of their second year of life, reaching sexual maturity at 5-6 years; the average life expectancy of a polar bear in the wild is estimated to be 25-30 years (DeMaster and Stirling, 1981).

Abundance and Range

Polar bears are circumpolar, occurring only in the Northern Hemisphere. Their range is determined by the Arctic ice pack and the landfast ice of the surrounding coastal areas. They will range during the winter along the southern edge of the ice pack or northern edge of ice formed off the coasts of the continents, while in the summer they will remain at the edge of the receding ice pack or in areas with landfast ice. Six populations of polar bears include Wrangel Island and western Alaska, northern Alaska, the Canadian Arctic archipelago, Greenland, Svalbard-Franz Josef Land, and Central Siberia (DeMaster and Stirling, 1981). The worldwide combined population estimate of polar bears is 21,500 to 25,000 in 20 populations (IUCN/SSC Polar Bear Specialist Group, 2002). Polar bears are protected by the International Agreement on Conservation of Polar Bears, ratified in 1976 (Prestrud and Stirling, 1994) and the U.S. Marine Mammal Protection Act of 1972.

Site Fidelity

It has been assumed that concentrated denning areas are maintained by fidelity of individual females to those sites. Pregnant females return to areas where they have successfully denned in the past (Uspenski and Kistchinski, 1972).

Ease of Census

Moderate

Feeding Habits

Polar bears are carnivorous, preying mainly on ringed seals, but they also hunt bearded seals, harp seals, hooded seals, walruses, sea birds, small mammals, and fish. They also may scavenge carrion of seals, walruses, or whales. They often eat only the high calorie blubber, which leads to the development of an insulating layer of fat, allowing the bears to store energy for times when food is scarce. If trapped on land for too long in the summer, polar bears will resort to eating vegetation (DeMaster and Stirling, 1981).

 

Polar Bear Contaminant Exposure Data

I.

Organochlorine Contamination

1.

Blood plasma samples taken from 32 polar bears collected in 1967 from eastern Svalbard were analyzed for organochlorines and were then compared with values from 1993-1994 (Derocher et al., 2003). The following are the geometric means of PCB concentrations (ng/g wet wt) in blood plasma listed as (adult males, 1967, N=24/adult males, 1993-1994, N=24/adult females, 1967, N=9/adult females, 1993-1994, N=21/subadults, 1967, N=9): PCB-28(0.8/-/0.6/-/0.7); PCB-33(0.8/-/0.6/-/0.6), PCB-52(0.4/-/0.3/-/0.3,) PCB-74(0.2/-/0.2/-/0.2), PCB-99(1.9/2.5/1.5/5.0/3.9), PCB-101(0.2/-/0.2/-/0.1), PCB-105(0.2/0.1/0.2/0.1/0.2), PCB-118(0.5/0.3/0.5/0.3/0.5), PCB-128(0.1/0.1/0.1/0.2/0.1), PCB-138(1.8/4.7/1.7/6.6/3.2), PCB-141(0.0/-/0.0/-/0.0), PCB-149(0.0/-/0.0/-/0.0), PCB-153(8.2/23.3/5.9/30.5/15.4) PCB-156(0.5/0.8/0.3/1.0/0.6), PCB-157(0.2/0.9/0.1/0.9/0.3), PCB-167(0.0/0/0.0/0/0.0), PCB-170(2.1/8.7/1.2/7.8/3.4), PCB-180(5.1/13.4/3.4/13.5/7.6), PCB-183(0.2/-/0.2/-/0.3) PCB-187(0.1/0.0/0.1/0.1/0.1), PCB-189(0.1/-/0.0/-/0.1), PCB-194(1.0/4.8/0.5/4.1/0.8), PCB-206(0.5/0.7/0.4/0.7/0.4), PCB-209(0.3/0.3/0.3/0.4/0.3).  The following are the geometric mean concentrations of pesticides found in the blood plasma from polar bears captured in 1967 listed as (adult males, N=24/adult females, N=9/subadults, N=9): o,p-DDT (0.0/0.0/0.0), p,p-DDT (0.6/0.2/0.1), o,p-DDE (0.0/0.0/0.0), p,p-DDE (1.7/1.4/1.6), o,p-DDD (0.0/0.0/0.0), p,p-DDD (0.4/0.5/0.3), ∑DDT (2.8/2.2/2.3), cis-CHL(0.0/0.0/0.0),  trans-CHL (0.0/0.0/0.0), cis-nonachlor (0.0/0.0/0.0), trans-nonachlor (0.3/0.2/0.4), oxychlordane (1.3/1.5/4.6), heptachlor (0.1/0.1/0.1), ∑CHL (1.8/2.0/5.2), α-HCH (0.8/0.5/0.8), β-HCH (1.4/0.6/2.0), γ-HCH (0.1/0.1/0.1), ∑HCH (2.5/1.3/2.9).  Differences in the organochlorine levels measured between 1967 and 1993-1994 are as follows: decreased in both sexes for PCB187 and p,p-DDE, unchanged in both sexes for PCBs 105, 118, 209, and HCH, increased in females for PCBs 99, 128, and CHL, and increased in both sexes for PCBs 138, 153, 156, 157, 170, 180, 194, and 206.

2.

Organochlorine residue levels were determined in muscle, brain, and adipose tissues of polar bears inhabiting waters of the Canadian Arctic and subarctic during 1968-1972 (Bowes and Jonkel, 1975). The following are the concentrations (µg/g wet wt) listed by age/sex (PCB/DDE/DDT): 8/m (7.37/0.350/0.162); 7/m (3.89/0.268/-); 7/m (0.194/0.019/0.015); cub/f (0.203/0.005/0.005); cub/m (0.090/0.009/0.003); 2.5/m (0.140/0.008/0.014); 6-7/m (0.713/0.005/0.002); -/f (0.089/0.0060.006); -/f (0.057/0.005/0.006); -/f (0.061/0.004/-); 10/f (4.12/0.432/0.214); a/f (0.190/0.009/0.010); 10-15/m (11.8/0.848/0.504); 17m (1.47/0.046/-); 17/m (0.124/0.007/-); 12/f (0.043/0.008/0.003); 4.5/m (0.039/0.006/0.004); 4.5/m (3.80/0.634/0.414); 10/f (0.026/0.004/0.006); 4/m (0.102/0.011/0.006); 3/m (0.202/0.003/-); 5/f (0.012/0.001/-); 22/m (0.130/0.023/0.004); -/f (1.42/0.105/-); 15/m (0.023/0.001/0.001); 6-7/f (0.038/0.001/-); cub/m (1.13/0.032/-); 17/m (0.025/0.003/0.005); 4/m (0.018/0.002/0.003); 5.5/m (2.12/0.183/0.122); 2-3/- (3.87/0.080/-); 4/m (0.030/0.005/-); 6/f (0.030/0.004/-); 6/f (0.010/0.001/-); 15/f (2.89/0.108/-); 18/f (2.84/0.107/0.055); 17/f (3.10/0.121/0.062); 5/f (1.62/0.146/0.055); 19/m (0.003/-/-); -/- (0.016/-/-); 12/f (0.009/-/-); 4/m (0.032/0.005/0.004); 3/m (0.033/0.003/0.001); -/f (0.017/0.001/-). PCB content in tissue generally increased from adult polar bears to polar bear cubs and young, and polar bear milk contained high concentrations of PCB.

3.

Samples of liver, kidney, and subcutaneous fat from 24 polar bears from Svalbard area during 1978-1989 were analyzed for chlorinated hydrocarbons (Norheim et al., 1992). The following are the mean concentrations (µg/g wet wt) of some of the pollutants listed as (adult liver, N=16/juvenile (<2 yrs), N=5/adult fat, N=7/juvenile fat, N=3): HCB 0.02/0.02/0.12/0.54; DDE 0.18/0.12/0.75/1.30; PCB 13/12/31/15. The mean concentrations for liver samples of 7 polar bears that were analyzed for β-HCH, oxychlordane, heptachlor, heptachlor epoxide, and dieldrin are 1.4, 8.5, 1.2, 0.8, and 0.8, respectively.

4.

Liver samples from 44 female and male polar bears, aged 3 to 29 years, from the Canadian arctic archipelago were obtained during 1982-1984 to be analyzed for organochlorines (Bandiera et al., 1997). The following are the mean concentrations (ng/g lipid wt) in the liver samples: PCB 17459; PCB-138 3579; CB-153 7460; PCB-170 2279; PCB-180 4219; total chlorinated benzenes 344; DDT 5078; chlordane 60031; dieldrin 6027. A positive correlation between cytochrome P450 1A and PCB levels in the liver samples suggests that cytochrome P450 1A was induced in polar bears by environmental exposure to PCBs.

5.

Polar bear liver and adipose tissue specimens from 121 bears collected in the Canadian Arctic and subarctic between 1982 and 1984 were analyzed for organochlorine compounds (Norstrom et al., 1988). The following are the average % of group in fat for identified organochlorines: total-PCB 0.5; PCB-47 0.5; PCB-99 8; PCB-118 0.5; PCB-146 1; PCB-153 42; PCB-137 1; PCB-138 11; PCB-187/182 0.5; PCB-183 1; PCB-156 1; PCB-157 0.5; PCB-180 17; PCB-170 11; PCB-194 4; PCB-206 1; technical chlordane (18,23) 3; U-1 4; nonachlor-III 16; trans-nonachlor 5; C-4 2; oxychlordane 63; heptachlor epoxide 7; pentachlorobenzene 25; hexachlorobenzene 75; DDT 19; DDE 81; α-HCH 71; β-HCH 29. The following are the mean concentrations (mg/kg lipid wt) of organochlorines in pooled adipose tissue lipid in polar bears listed by zone as (total-PCB/total-CHLOR/total-CBz/total-DDT/total-HCH/dieldrin):

H1: 6/4.25/2.31/0.19/0.14/0.52/0.19; H2: 8/3.95/1.81/0.21/0.18/0.32/0.17;

G: 8/8.25/3.42/0.26/0.28/0.30/0.21; E1: 6/6.63/3.81/0.27/0.12/0.31/0.30;

E2: 16/4.43/3.68/0.23/0.22/0.79/0.50; F1: 18/5.94/3.72/0.25/0.30/0.62/0.53;

F2:10/4.22/2.86/0.40/0.21/0.33/0.38; D1: 10/3.24/2.75/0.26/0.39/0.37/0.37;

D2+D3: 20/4.25/2.73/0.25/0.41/0.36/0.34; C: 10/8.11/6.89/0.33/0.94/0.59/0.85;

A1: 9/8.02/7.09/0.30/1.19/0.87/0.96. The correlation between organochlorine levels in pooled adipose tissue and mean levels in liver was highly significant for all organochlorines.

6.

Organochlorine concentrations were determined in the adipose tissue of 10 polar bears collected in Barrow Strait in 1982 and in 10 polar bears collected in Pond Inlet/north Baffin Island in 1984 (Muir et al., 1988). The following are the arithmetic mean concentrations (ng/kg wet wt) listed as (Admirality Inlet/Barrow Strait): total HCH 330/443; total Chlorobenzenes 446/337; total Chlordane 2971/2670; total DDT 210/213; dieldrin 375/381; total PCB 4572/4420; total Chlordane/PCB 0.66/0.61; total DDT/PCB 0.05/0.05; DDE/total DDT 0.78/0.70.

7.

Concentrations of tris(4-chlorophenyl)-methanol (TCP methanol) and other organochlorines were determined in blubber, liver, and kidney samples from polar bears collected from Saint Lawrence River between 1983-1985 (Jarman et al., 1992). The following are the mean concentrations (ng/g lipid wt) listed by location as (tissue/N/TCPM/∑DDT/∑PCB/dieldrin): Churchill: (kidney/8/110/530000/18000/600), (liver/1/6800/32000/94000/6700); Rankin Island: (liver/1/4000/10000/62000/26000); Pound Inlet: (fat/1/35/290/6300/370).

8.

Levels of PCB methyl sulfones (MeSO2-CBs) and DDE methyl sulfones (MeSO2-DDEs) were determined in blubber and liver tissues from two polar bears from western Hudson Bay in 1985 (Bergman et al., 1994). The following are the concentrations (µg/kg, extracted lipids) listed as (blubber (polar bear 1/polar bear 2), liver (polar bear 1/polar bear 2): 3-MeSO2-2,5,2’,4’-tetra-CB (0.05/0.06, 0.3/0.3); 4-MeSO2-2,5,2’,4’-tetra-CB (0.06/0.05, 0.4/0.3); 2-MeSO2-DDE (ND/ND, 0.9/0.6); 3-MeSO2-2,5,2’,4’,5’-penta-CB (0.09/0.1, 0.3/0.3); 4-MeSO2-2,5,2’,4’,5’-penta-CB (0.1/0.1, 0.2/0.2); 3-MeSO2-DDE (ND/ND, 0.4/0.4); 3-MeSO2-2,5,2’,3’,4’-penta-CB (0.04/0.04, 0.6/0.5); 4-MeSO2-2,5,2’,3’,4’-penta-CB (0.1/0.1, 0.3/0.2); 3-MeSO2-2,5,2’,3’,4’,5’-hexa-CB (0.02/0.01, 0.1/0.1); 4-MeSO2-2,5,2’,3’,4’,5’-hexa-CB (0.02/0.02, 0.03/0.02); Total MeSO2-CB (0.6/0.8, 3.0/2.7); Total MeSO2-DDE (ND/ND, 1.3/1.0); Total PCB (15.0/16.7, 21.7/29.5); Total DDT (0.79/0.79, 2.26/2.33).

9.

Blood samples from 90 adult female polar bears were collected from the Svalbard area eastward to the Chukchi Sea during 1987-1995 to be analyzed for PCBs (Andersen et al., 2001). The following are the mean concentrations (ng/g lipid wt) listed as (Svalbard/Franz Josef Land/Kara Sea/East-Siberian Sea/Chukchi Sea): PCB-99 (443/1427/1371/577/435); PCB-118 (31/44/39/45/43); PCB-153 (2658/5071/4692/2043/1246); PCB-156 (65/220/167/61/54); PCB-180 (1411/3570/2637/708/586); PCB-194 (365/730/408/84/76); ∑PCB (5043/11194/9412/3564/2465). The lower chlorinated PCBs are increasing, and the high chlorinated PCBs are decreasing from Svalbard eastward to the Chukchi Sea.

10.

Blood samples from 90 adult female polar bears (age ≥5) were collected from the Svalbard area eastward to the Chukchi Sea during 1987-1995 and analyzed for organochlorines (Lie et al., 2003). The following are the mean concentrations (ng/g lipid wt) listed as (Svalbard/Franz Josef Land/Kara Sea/East-Siberian Sea/Chukchi Sea): HCB 125/224/261/188/237; Oxychlordane 1234/2966/2536/2739/2112; Trans-nonachlor 97/200/204/137/109; α-HCH 52/58/35/109/186; β-HCH 142/158/260/297/393; DDE 58/84/94/38/19.

11.

The adipose tissue of a three-year-old female polar bear was collected at Repulse Bay in 1989 and analyzed for polychlorocamphenes (PCCs) (Zhu and Norstrom, 1993). The following are the concentrations (ng/g lipid wt) of PCCs and other major chlorinated xenobiotics. PCB-153 5500; s-CBz 480; s-HCH 690; s-CHLOR 11500; s-DDT 940; s-PCB 11600; s-PCC 1060.

12.

Polar bear fat samples from 52 polar bears collected from Sanikiluaq, Sleeper Island, Iqaluit, Lake Harbour, and Pangnirtung in 1989-1990 were analyzed for organochlorines (Zhu et al., 1995). The following are the mean concentrations (ng/g lipid wt): photoheptachlor 145; heptachlor epoxide 475; oxychlordane 2652; nonachlor III 545; trans-nonachlor 470; cis-nonachlor ND; trans-chlordane ND; cis-chlordane ND; total Chlordane 4287; total PCB 10293.

13.

Male polar bear adipose samples from 12 arctic and subarctic regions from the Bering Sea to the Greenland Sea during 1989-1991 were analyzed for organochlorines (Letcher et al., 1995). The following are the mean concentrations (ng/g lipid wt) listed by parent PCB/MeSO2-PCB as (Bering Sea, N=3/Beaufort Sea, N=3, V. Melville Sound, N=4/ Queen Maud Gulf, N=5/Barrow Strait, N=10/ Boothia Gulf, N=5/ North Baffin Bay, N=10/South Baffin Bay, N=5/ Davis Strait, N=3/ North Hudson Bay, N=27/Southeast Hudson Bay, N=9/Scoresby Sound, N=10):

PCB-49/3M-CB49 6.9/11.5/25.2/15.2/11.8/5.6/17.3/19.8/14.6/13.1/19.2/36.7;

PCB-49/4M-CB49 6.6/12.9/26.8/16.9/12.5/6.8/15.2/20.2/13.8/12.5/18.3/34.8;

PCB-64/4M-CB64 4.2/9.8/17.3/13.4/10.1/4.6/10.0/10.2/7.3/5.8/11.9/15.8;

PCB-101/3M-CB101 21.3/23.1/42.3/29.4/22.4/19.6/39.5/67.8/47.2/35.6/35.7/81.9;

PCB-101/4M-CB101 27.1/30.2/59.8/40.9/28.9/23.5/38.2/65.3/39.0/37.0/44.0/78.1;

PCB-70/3M-CB70 3.2/6.8/10.6/6.7/5.0/1.9/6.5/11.5/6.7/5.3/7.8/15.8;

PCB-70/4M-CB70 4.9/8.4/14.7/11.5/8.0/2.5/7.4/10.1/7.7/6.0/9.8/15.8;

PCB-87/3M-CB87 10.3/17.7/40.1/24.8/19.4/11.0/27.9/51.6/23.1/18.8/28.9/61.3;

PCB-87/4M-CB87 23.2/54.0/89.2/58.8/41.8/29.7/47.9/86.1/47.2/37.8/60.9/115.9;

PCB-149/3M-CB149 1.9/4.9/7.5/4.1/3.7/1.5/4.5/11.7/6.0/3.9/7.6/18.8;

PCB-149/4M-CB149 11.1/34.0/56.4/34.7/26.3/12.0/29.6/47.4/34.6/20.2/41.9/69.4;

PCB-132/3M-CB132 1.2/6.6/4.5/2.4/1.6/1.3/2.8/5.8/3.0/2.5/4.1/12.7;

PCB-132/4M-CB132 7.2/12.1/23.0/12.8/10.5/11.3/17.9/20.3/16.8/6.8/14.3/33.0;

PCB-141/3M-CB141 4.4/5.2/8.9/4.0/5.3/5.5/11.0/20.0/8.2/5.3/8.4/16.8;

PCB-141/4M-CB141 3.6/6.8/13.3/6.0/5.8/5.9/7.4/14.4/6.9/5.3/9.1/17.4;

PCB-174/3M-CB174 0.8/0.9/1.5/0.9/0.7/1.2/1.4/4.0/2.5/1.3/1.3/3.6;

PCB-174/4M-CB174 0.4/2.0/3.8/1.6/1.5/0.6/2.4/4.1/1.9/1.1/2.7/5.1;

PCB-99 108.6/393.1/553.4/396.0/263.1/142.0/329.2/368.5/521.4/170.4/613.3/753.5;

PCB-180 292.7/1126.8/1540.0/790.3/683.7/513.1/1011.0/2185.4/1667.1/869.1/1176.3/3411.8;

PCB-149 0.0/1.6/3.3/1.9/0.0/2.0/2.2/3.3/2.1/3.5/3.1;

S-MeSO2-PCBs 138.2/246.8/444.8/283.7/215.1/144.7/287.1/470.2/286.3/218.3/326.0/632.7;

S-PCBs 1737/5396/6181/4595/3361/2529/4720/8863/7637/4280/6690/13730;

3-MeSO2-DDE 0.8/1.8/2.7/1.1/1.9/0.6/3.6/4.4/3.2/2.1/2.8/11.0;

DDE 24.3/50.5/55.1/20.1/74.6/32.6/88.3/82.5/170.1/185.2/314.3/209.0.

14.

Adipose tissue samples from polar bears were obtained between 1989-1993 from Wrangel Island in Russia, most of the bear’s range in North America, eastern Greenland, and Svalbard and analyzed for organochlorines (Norstrom et al., 1998). The following are the mean concentrations (µg/kg lipid wt) listed by region as (sex/N/∑Chlordanes/DDE/∑PCB/dieldrin): R1: f/16/1016/298/5535/31, m/1/923/120/2849/36; R2: f/6/1396/91/2058/42, m/3/1053/90/2380/51; R3: f/13/4709/266/13818/157, m/11/2689/435/22391/130; R4: f/9/2146/93/3772/80, m/3/1364/71/4732/103; R5: f/13/2613/116/5193/105, m/9/2245/166/11357/19(N=6); R6: f/9/2981/71/3372/67(N=9), m/4/2293/38/3853/not measured; R7: f/2/2753/197/3087/122, m/8/1734/106/4266/167; R8: f/5/2679/97/2245/216, m/5/1211/67/2919/93; R9: f/9/2339/278/3244/138, m/9/2428/147/7633/249; R10: f/1/3492/349/6836/not measured, m/4/4618/432/6258/17(N=3); R11: f/11/2942/246/3774/73(N=9), m/18/2093/224/5648/191(N=17); R12: f/62/2738/302/3965/107(N=57), m/36/1765/253/6022/108(N=33); R13: f/3/7937/867/10939/400, m/9/4380/528/9685/316; R14: f/6/2825/268/4564/174, m/3/2315/213/8037/227; R15: f/9/5044/278/22419/384, m/9/2729/305/18232/122(N=8); R16: f/8/3162/253/12775/189, m/6/5616/413/29409/344. Differences in concentrations of the organochlorines among three sex categories are as follows, listed as (female with cubs, N=56/solitary female, N=110/male, N=137): ∑CHL 2756/2793/2126; DDE 258/191/210; ∑PCB 4557/4812/7246; dieldrin 101(N=52)/118(N=105)/104(N=124). Concentrations of ∑PCB were 46% higher in adult males than females, and there was no significant trend with age. Concentrations of ∑CHL were 30% lower in adult males than females. ∑PCB concentrations in bears from Svalbard, East Greenland, and the Arctic Ocean near Prince Patrick Island were similar and significantly higher than most other areas.

15.

Organochlorine concentrations were determined in 6 polar bear milk samples from Svalbard (Norway), 1990-1991 (Oehme et al., 1995). The following are the average concentrations (pg/ml whole milk): 2,3,7,8-TCDD 0.20; 1,2,3,7,8-PeCDD 0.45; 1,2,3,4,7,8-HxCDD 0.10; 1,2,3,6,7,8-HxCDD 0.33; 1,2,3,7,8,9-HxCDD 0.028; 1,2,3,4,6,7,8-HpCDD 1.4; OCDD 14; 2,3,7,8-TCDF 0.14; 1,2,3,7,8-PeCDF 0.042; 2,3,4,7,8-PeCDF 0.33 1,2,3,4,7,8-HxCDF 0.050; 1,2,3,6,7,8-HxCDF 0.036; 1,2,3,7,8,9-HxCDF --; 2,3,4,6,7,8-HxCDF 0.050; 1,2,3,4,6,7,8-HpCDF 0.19; 1,2,3,4,7,8,9-HpCDF 0.030; OCDF 0.52; TEQs (PCDD/D) 0.69; 3,3’4,4’-TeCB 35; 3,3’4,4’,5-PeCB 15; 3,3’4,4’,5,5’-HxCB 32; TEQs (PCB) 3.5.

16.

Subcutaneous tissue, blood, and milk were collected from polar bears from Svalbard during 1990-1994 and analyzed for organochlorine contaminants (Bernhoft et al., 1997). The following are the mean concentrations (ng/g lipid wt) in subcutaneous lipid listed as (young, N=8/subadults, N=25/adult females, N=23/adult males, N=20/old males, N=9): chlordanes 3380/3440/3150/1250/613; DDE 567/305/372/340/342; HCB 200/191/192/215/238; HCHs 233/197/163/385/318; PCB-99 1270/1190/1200/1300/706; PCB-105 33/23/31/40/47; PCB-118 49/39/76/98/108; PCB-128 44/30/43/63/45; PCB-138 1250/1140/1330/1620/922; PCB-153 5020/7080/5930/10800/4680; PCB-156 132/189/166/271/193; PCB-157 133/198/125/320/254; PCB-170 1110/1820/1490/3830/2560; PCB-1801980/3720/3470/7530/4220; PCB-187 14/21/29/31/25; PCB-194 373/828/1030/1900/2360; PCB-206 31/100/173/236/289; PCB-209 11/35/114/121/187; ∑PCB 11400/16400/15700/28100/16600. The following are the median concentrations in blood cells of adult females listed as (with cubs of the year, N=11/with yearlings, N=8/with 2-yr-olds or without young, N=16): Chlordanes 2500/1330/2840; DDE 48/68/102; HCB 227/84/171; HCHs 374/129/310; PCBs 6460/4520/8640. The following are the concentrations in blood cells of individual female polar bears sampled two or more years listed as (chlordane/DDE/HCB/HCHs/PCBs): Bear 7768: 1990 (2520/64/165/225/7490), 1991 (4060/<40/222/263/20900), 1993 (2240/61/154/327/5870); Bear 7771: 1990 (1890/56/86/113/7150), 1991 (4270/42/504/116/1300); Bear 7773: 1990 (1310/150/76/168/3950), 1991 (3650/81/186/264/17900), 1993 (1970/110/141/299/6650); Bear 7802: 1991 (3890/110/234/338/9970), 1992 (2290/<40/100/687/11200); Bear 7803: 1991 (4870/<40/188/247/9570), 1992 (722/<40/42/<90/2710); Bear 7817: 1992 (920/130/80/<90/2220), 1993 (3210/93/338/416/8070); Bear 7822: 1992 (811/71/81/103/2590), 1993 (2810/61/160/374/6840); Bear 7781(male): 1992 (342/<40/138/279/7730), 1993 (374/<40/73/402/4230). The following are the median concentrations in blood cells of young polar bears (3-6 yrs) for 5 different sampling years listed as (1990, N=5/1991, N=8/1992, N=12/1993, N=10/ 1994, N=4): chlordanes 1940/1410/1720/3430/1830; DDE 120/69/100/115/114; HCB 294/187/189/190/254; HCHs 522/256/180/503/183; PCBs 10400/6010/6040/11400/5980. The following are median concentrations in blood cells of mating available female polar bear listed as (bears that denned the next winter, N=13/bears that did not den, N=3): chlordanes 3080/2600; DDE 110/<40; HCB 195/138; HCHs 299/408; PCBs 8070/8890.

17.

Plasma, blood cells, milk and subcutaneous fat samples were collected from polar bears captured in the Svalbard area from 1990-1998 and analyzed for PCBs (Henriksen et al., 2001). The mean concentrations (ng/g wet wt) of PCB-153 for 10 polar bears found in the plasma, blood cells, milk, and subcutaneous fat are 23, 4, 370, and 2259, respectively. The mean concentrations of PCB-153 in 64 bears found in the plasma, subcutaneous fat and blood cells are 27, 2372, and 5, respectively. Plasma samples were examined in 323 bears with an overall mean PCB-153 concentration of 33. PCB-153 decreased significantly in the plasma.

18.

Blood plasma samples from 56 polar bears captured in eastern Svalbard during 1991-1994 were analyzed for organochlorines (Bernhoft et al., 2000). The following are the median concentrations (ng/g wet wt): chlordanes 13.1; DDE 0.41; HCB 1.09; HCHs 2.08; PCB-99 3.54; PCB-105 0.14; PCB-118 0.32; PCB-128 0.16; PCB-138 5.76; PCB-153 26.9; PCB-156 0.93; PCB-157 0.97; PCB-170 8.16; PCB-180 15.0; PCB-187 0.06; PCB-194 4.00; PCB-206 0.67; PCB-209 0.40; ∑PCBs 66.7. Immunoglobulin G levels were negatively correlated with ∑PCB, three individual PCB congeners (99, 194, and 206), and HCB.

19.

Blood plasma samples from 79 polar bears captured in eastern Svalbard between 1991 and 1994 were analyzed for organochlorines (Skaare et al., 2001). The following are the median concentrations (ng/g wet wt): chlordanes 14.1; DDE 0.53; HCB 1.25; HCHs 2.09; PCB-99 4.07; PCB-105 0.17; PCB-118 0.38; PCB-128 0.18; PCB-138 5.99; PCB-153 27.4; PCB-156 0.89; PCB-157 0.97; PCB-170 7.70; PCB-180 15.0; PCB-187 0.06; PCB-194 3.77; PCB-206 0.59; PCB-209 0.39; ∑PCBs 72.0. The retinol concentration and the ratio of total T4 (thyroid hormones) to free T4 decreased linearly with increasing concentrations of PCBs and HCB. Retinol was also negatively associated with HCHs, while the ratio of total T4 to free T4 was positively associated with DDE.

20.

Blood samples for PCB analyses were collected from 54 adult female polar bears that were caught in the Barents Sea between Svalbard and Franz Josef Land during the period 1991-1998 (Olsen et al., 2003). The following are the mean concentrations (ng/g wet wt): PCB-99, 568; PCB-118, 35; PCB-153, 2881; PCB 156, 88; PCB-180, 1672; PCB194, 387; ∑PCB, 5595. Concentrations grouped according to reproductive status are as follows, listed as (∑PCB/PCB-118): females with cubs of the year (N=19), 5538/27; females with yearlings (N=9), 4950/40; single females (N=26), 5872/39.

21.

Organochlorine concentrations were determined in tissue samples from polar bears collected in the vicinity of Churchill, Manitoba between 1992-1993, before and after a lengthy period of fasting (Polischuk et al., 1995). The following are the mean concentrations (µg/g lipid wt) found in polar bear adipose tissue after a period of fasting listed as (DDT, first sample/DDT second sample/HCH first sample/HCH second sample): solitary/pregnant, N=3 (0.27/0.19/0.31/0.33); female with cub of the year, N=1 (0.51/0.50/0.37/0.54); female with yearling, N=1 (0.48/0.25/0.38/0.34); cub of the year, N=1 (0.85/0.79/0.77/0.75); yearling, N=1 (0.40/0.70/0.46/0.50). The following are the mean concentrations found in polar bear milk after a period of fasting listed as (DDT, first sample/DDT second sample/HCH first sample/HCH second sample): solitary/pregnant, N=3 (-/0.13/-/0.88); female with cub of the year, N=1 (0.16/0.26/0.48/0.90); female with yearling, N=1 (0.56/0.23/0.78/0.70); cub of the year, N=1 (0.85/0.79/0.77/0.75); yearling, N=1 (0.40/0.70/0.46/0.50). Concentrations of PCBs, CHLORs, and CBzs in adipose tissue tended to increase as the fasting period progressed, while concentrations of DDTs and HCHs did not show any relationship. The sums of PCBs, CHLORs, and CBzs in milk consistently increased in concentration during the fasting period, while the sums of DDTs and HCHs were more erratic.

22.

Polar bear fat (N=7) and liver samples (N=13) were collected from male polar bears (3-22 years of age) in the Resolute Bay area of the Canadian Arctic during 1992-1993 to be analyzed for organochlorines (Wiberg et al., 2000). The following are the mean concentrations (ng/g lipid wt) listed as (fat/liver): (+)-trans-chlordane 0.20/7.3; (-)-trans-chlordane 0.02/2.3; (+)-cis-chlordane 0.07/2.5; (-)-cis-chlordane 0.02/2.0; octachlordanes ranged 3.6/18 to 29-190; nonachlordanes ranged 130/320 to 370/2000; trans-nonachlor 300/250; cis-nonachlor n.a./n.a.; MC2 53/120; technical chlordane (33) 43/950; C-5 33/230; Unidentified clordane-2 40/245; Unidentified chlordane -3 100/28; Unidentified chlordane -4 7/500; heptachor-epoxide 300/2200; oxychlordane 1500/11000; (+)-α-HCH400/440; (-)-α-HCH 190/130; β-HCH 130/69; γ-HCH n.a./n.a.; PCB-153 2700/7700.

23.

Liver samples were collected from 16 adult male polar bears in the Canadian arctic between 1992 and 1994 and analyzed for chlorinated hydrocarbon contaminants and metabolites, determination of alkoxyresorufin O-dealkylase activities and immunoquantitation of cytochrome P450 (CYP) protein levels (Letcher et al., 1996). The following are the mean concentrations (ng/g lipid wt): PCB-77 0.025; PCB -126 0.244; PCB -69 0.404; 2378-TnCDD 0.019; 12378-PnCDD 0.005; 123478-Hx CDD 0.002; 123678-HxCDD 0.002; 12346789-OCDD 0.004; 12478-PnCDF 0.002; 23478-PnCDF0.010; PCB -37 0.097; PCB -81 n.a.; PCB -105 52;  CB-118 139; PCB -138 2331; PCB -170 1993; PCB -156 130; PCB -157 113; PCB -189 0.110; PCB -99 1660; PCB -153 7469; PCB -154 7; PCB -180 3340; PCB -183 159; PCB -194 559; S-MeSO2-PCB 1851; S-3-MeSO2-PCB 1071; S-4-MeSO2-PCB 780; chlordane 30770; DDT 951; Zolazepam 11; ∑PCB 18680. Total CYP content was variable among bears and ranged between 1 and 2 nmol/mg microsomal protein. The following activities are the mean concentrations (pmol/min/mg): EROD 1165±454, PROD 21±7, BROD 185±59. BROD activities did not exactly parallel PROD or EROD activities. CYP2B content averaged 21.1±11.2 pmol/mg protein and was significantly greater than the mean CYP1A content 4.9±3.4pmol/mg protein. CYP1A and CYP2B were a more reliable measure of exposure to CHC inducers than alkoxyresorufin O-dealkylase activities in polar bear.

24.

Organochlorine concentrations were determined in free-ranging polar bears, categorized by age and sex before and after a fast averaging 56 days, from Churchill, Manitoba between 1992 and 1995 (Polischuk et al., 2002). The following are the mean organochlorine concentrations (µg/kg, lipid wt) in adipose tissue listed as (females with cubs-of-the-year (N=9) before fast, after fast/females with yearling cubs (N=7) before fast, after fast/cubs-of-the-year (N=12) before fast, after fast/yearling cubs (N=9) before fast, after fast/subadult and adult males (N=10) before fast, after fast):

∑-Chlorobenzenes (105,143/116,149/239,261/177,224/149,186),

∑-HCHs (171,183/177,182/249,201/197,229/240,146),

∑-CHLORs (1835,2820/2406,2723/4717,6123/3506,4798/4145,2155),

∑-DDTs (196,149/244,189/196,128/223,221/238,149),

∑-PCBs (2063,3163/2601,3476/4261,5508/3876,5158/3409,3975).

The following are the means for the total body burden (mg) of organochlorines listed the same as above:

∑- Chlorobenzenes (7,6/7,7/4,4/7,7/15,13), ∑-HCHs (12,9/10,8/4,3/8,8/25,10),

∑-CHLORs (127,126/137,112/70,80/137,151/371,124),

∑-DDTs (14,7/15,8/3,2/9,8/26,12),

∑-PCBs (142,140/150,152/62,71/150,160/277,247).

The following are the mean animal concentrations (µg/kg, whole body wt) of organochlorines listed the same as above:

∑- Chlorobenzenes (32,35/33,36/57,62/53,62/43,46),

∑-HCHs (52,46/49,43/59,48/60,65/65,36),

∑-CHLORs (551,684/672,635/1074,1430/1024,1299/1048,501),

∑-DDTs (60,38/69,45/48,31/67,62/70,37),

∑-PCBs (618,758/724,829/958,1276/1125,1389/847,911).

25.

Fat samples were collected from 6 adult male polar bears from the Canadian high Arctic during 1993 to be analyzed for organochlorines (Letcher et al., 1998). The resulting mean concentrations (ng/g lipid wt) for ∑DDT, DDE, ∑PCB, ∑MeSO2-PCB, and 3-MeSO2-DDE are 301, 268, 6207, 432, and 2.0, respectively. Concluded that MeSO2-PCBs have high biomagnification potential in food chains.

26.

Organochlorine residues were analyzed in the liver and adipose tissue of one mature polar bear that was accidentally killed in Iceland in 1993 (Klobes et al., 1998). The organochlorine concentrations (µg/kg, wet wt) found in the polar bear are as follows, listed as (liver / adipose tissue): α-HCH 12 / 98; (+)-α-HCH 9 / 59; (-)-α-HCH 4 / 52; α-HCH ER(+/-) 2.2 / 1.1; β-HCH 16 / 84; γ-HCH 8 / 8; HCB 15 / 102; PCB-118 14 / 93; PCB-153 702 / 3861; PCB-138 168 / 667; PCB-163 99 / 223; PCB-180 458 / 1739; PCB-170 168 / 890; PCB-194 55 / 390; DDD 161 / n.d.; DDE 109 / 678; trans-nonachlor 74 / 673; cis-nonachlor n.d. / 77; oxychlordane 1685 / 816; (+)-oxychlordane 1000 / 520; (-)-oxychlordane 750 / 390; oxychlordane ER(+/-) 1.3 / 1.3; B8-1413 (Parlar #26) n.d / 53; B8-1413 ER(1/2) - / 1.7; B9-1679 (Parlar #50) n.d / 76; B9-1679 ER(1/2) - / 1.4.

27.

Polar bear livers collected from northern and western Alaska during 1993-2000 were analyzed for organochlorines (Kumar et al., 2002). The mean concentrations of PCDD/DFs and 14 dioxin-like PCBs were 26 pg/g (lipid wt) and 2230 ng/g. TEQs of PCDDs, PCDFs and dioxin-like PCBs ranged from 69-192 pg/g.

28.

Between 1995-1998, samples were collected from 121 male polar bears from the Svalbard area to be analyzed for organochlorines (Oskam et al., 2003). Polar bears were divided into four quartiles based on the mean plasma testosterone concentrations (ng/ml) and are as follows: quartile 1 = 0.08; quartile 2 = 0.27; quartile 3 = 3.7; quartile 4 = 22.0. The following are the mean concentrations (ng/g wet wt) listed as ((quartile) 1/2/3/4): HCB 2.79/2.42/2.22/1.07; α-HCH 0.24/0.27/0.23/0.22; β-HCH 2.15/1.09/1.00/0.64; oxychlordane 35.3/19.4/6.4/3.5; trans-nonachlor 1.3/1.5/1.1/0.8; DDE 0.8/0.8/0.5/0.3; PCB-47 0.77/0.90/0.9/0.9; PCB-99 21.9/10.0/6.3/3.3; PCB-118 0.31/0.51/0.35/0.31; PCB-128 0.31/0.26/0.14/0.10; PCB-137 1.43/0.78/0.42/0.22; PCB-138 16.5/8.9/6.0/3.6; PCB-153 87.8/44.6/31.5/17.8; PCB-156 2.95/1.45/1.11/0.70; PCB-157 3.12/1.50/1.43/0.98; PCB-170 24.5/11.9/12.1/8.7; PCB-180 51.0/23.6/22.8/15.1; PCB-183 0.63/0.33/0.25/0.13; PCB-187 0.05/0.05/0.04/0.02; PCB-189 40.8/28.6/38.6/40.96; PCB-194 8.6/5.6/5.7/5.9; PCB-206 0.92/0.67/0.67/0.70; ∑PCBs (ng/ml) 221/111/90.2/58.9. There were significant reductions in ∑pesticides, β-HCH, and oxychlordane with increasing plasma testosterone concentrations. Of the 16 individual PCB congeners, PCBs 99, 128, 137, 138, 153, 156, 157, 180, and 183 showed significant reductions with increasing testosterone concentrations.

29.

Between 1995-1998, samples were collected from 121 male and 130 female polar bears from the Svalbard area to be analyzed for organochlorines (Oskam et al., 2004). Polar bears were divided into four quartiles based on the mean plasma cortisol concentrations (ng/ml) and are as follows: quartile 1 = 41.1; quartile 2 = 101.1; quartile 3 = 174.0; quartile 4 = 272.7. The following are the mean concentrations (ng/g wet wt) listed as ((quartile) 1/2/3/4): HCB 2.9/1.9/2.1/1.8; α-HCH 0.3/0.3/0.2/0.2; β-HCH 1.6/0.9/0.9/0.7; oxychlordane 34.1/15.6/14.7/14.4; trans-nonachlor 1.6/1.2/1.2/1.3; DDE 0.7/0.5/0.5/0.8; PCB-47 0.87/0.75/1.36/0.97; PCB-99 16.9/8.7/8.8/7.5; PCB-118 0.33/0.30/0.35/0.41; PCB-128 0.296/0.16/0.17/0.19; PCB-137 1.097/0.57/0.60/0.53; PCB-138 13.7/7.5/8.0/7.5; PCB-153 69.5/39.1/40.3/31.2; PCB-156 2.2/1.3/1.3/1.1; PCB-157 2.25/1.45/1.47/1.195; PCB-170 18.5/12.8/13.2/10.2; PCB-180 39.1/26.6/27.7/21.8; PCB-183 0.495/0.32/0.32/0.38; PCB-187 0.495/0.32/0.32/0.38; PCB-189 0.43/0.32/0.396/0.28; PCB-194 6.92/5.51/6.9/4.65; PCB-206 0.80/0.68/0.89/0.62; total mean ∑PCBs (for all quartiles) 120; total mean ∑pesticides (for all quartiles) 25.2. Both ∑pesticides and ∑PCBs showed negative trends for the plasma cortisol concentration. HCB, α-HCH, β-HCH, and oxychlordane showed a negative relationship with the plasma cortisol concentration. PCB 99, 153, 156, 157, 170, and 180 showed negative trends as well.

30.

Blood samples for organochlorine analysis were collected from 86 adult female polar bears from Svalbard, Hopen, Edgeoya, and the Barents Sea region during 1995-1998 (Haave et al., 2003). The following are the mean concentrations (ng/g lipid wt) listed as (single, N=32)/with cubs, N=36)/with yearlings, N=18): PCB-118 9740/8919/5895; PCB 25/21/25.

31.

Concentrations of PCBs were determined in two yearling sibling polar bears as well as their 11-yr-old mother that were captured at Svalbard in April 1996 (Wiig et al., 1998). The concentrations (ng/g fat wt) of PCBs in the mother and the twins were analyzed in blood plasma and were 1856, 6288, and 4707, respectively.

32.

Subcutaneous fat samples were taken from 5 polar bears collected near Barrow, Alaska in 1996 and analyzed for persistent organochlorine pollutants (Kucklick et al., 2002). The following are the concentrations (ng/g wet wt) for each of the 5 polar bears listed respectively: PCB-18 7.62/7.11/6.14/6.40/12.0; PCB-31 4.65/4.55/3.48/4.18/8.93; PCB-28 4.31/5.40/4.76/5.92/10.4; PCB-52 4.13/5.63/9.17/6.27/6.37; PCB-49 4.82/4.17/8.24/4.03/2.94; PCB-44 5.54/5.97/8.60/8.70/4.19; PCB-66 8.33/15.0/27.0/27.6/9.81; PCB-95 4.10/4.63/4.62/4.24/2.87; PCB-101+90 14.6/14.7/13.9/13.3/4.35; PCB-99 554/361/393/329/258; PCB-87 <1.3/<1.3/<1.3/<1.3/2.17; PCB-110 <3.1/<3.1/<3.1/<3.1/<3.1; PCB-151 <1.2/<1.2/<1.2/<1.2/<1.2; PCB-149 <1.4/2.53/2.81/<1.4/<1.4; PCB-118 30.6/43.4/59.1/80.3/26.7; PCB-153 2548/1614/1617/1310/1113; PCB-105 14.3/17.5/21.2/26.0/10.3; PCB-138+158+160 463/390/295/337/210; PCB-187 9.4/17.8/14.9/16.5/6.24; PCB-183 54.1/52.9/40.4/47.8/29.1; PCB-128 15.2/17.6/9.7/11.4/5.40; PCB-156 99.4/51.3/49.0/42.8/37.1; PCB-201 <1.9/<1.9/<1.9/<1.9/<1.9; PCB-180 1129/539/401/288/310; PCB-170 610/276/248/136/171; PCB-195 6.27/5.29/2.96/3.20/1.62; PCB-194 309/98.5/58.5/33.9/40.9; PCB-206 78.0/24.7/10.7/8.45/7.55; PCB-209 31.8/12.3/2.99/3.14/1.63; ∑PCB 6010/3590/3312/2754/2292; hexachlorobenzene 451/128/79.0/94.1/163; α-HCH 63.5/191/97.4/169/160; β-HCH -/-/-/-/355; γ-HCH10.2/8.96/8.90/6.39/<1.2; ∑HCH73.7/200/106/175/515; heptachlor <2.1/<2.1/<2.1/<2.1/3.57; trans-chlordane 3.62/3.27/4.77/5.15/3.28; cis-chlordane 4.87/3.71/3.69/<1.0/<1.0; trans-nonachlor 62.6/205/179/177/96.1; cis-nonachlor3.37/6.42/<1.0/4.34/2.12; heptachlor epoxide 61.30/113/140/164/114;  oxychlordane 196/351/513/495/983; ∑chlordane 332/682/840/846/1202; dieldrin 253/99.9/106/109/126; 2,4’-DDE <1.4/<1.4/<1.4/<1.4/<1.4; 4,4’-DDE 17.8/81.9/88.9/101/18.3; 2,4’-DDD <1.9/<1.9/<1.9/<1.9/<1.9; 4,4’-DDD <1.4/4.42/4.84/<1.4/<1.4; 2,4’-DDT 25.5/<2.2/<2.2/<2.2/6.98; 4,4’-DDT 14.4/14.3/24.4/23.5/9.44; ∑DDT 57.7/101/118/124/34.8.

33.

Polar bear plasma samples collected from 30 polar bears captured in 1997 around the Resolute Bay area (Canada) were analyzed for organochlorines (Sandau et al., 2000). The following are the mean concentrations (ng/g wet wt): 4-Hydroxyheptachlorostyrene 9.11; PCP 0.210; ∑OH-PCBs 92.6; ∑phenolics 103; OCS 0.348; CB-153 20.2; ∑PCBs 46.9. Mean concentrations (ng/g lipid wt) of CB-153 and OCS for adipose tissue samples (N=8) are 2670 and 14, respectively, and for liver tissue samples (N=8) are 6840 and 156, respectively.

34.

Concentrations of PCBs were determined in two groups of female polar bears, females with cubs of the year (FWCOY) and females without cubs of the year (FWOCOY), and within a group of male polar bears collected from Svalbard, Norway between 1997-1998 (Braathen et al., 2004). The following are the mean concentrations (ng/g wet wt) of PCB congeners in plasma listed as (FWCOY, N=17/FWOCOY, N=35/Males, N=29): PCB-99 9.01/8.50/7.41; PCB-118 0.23/0.31/0.33; PCB-153 41.1/37.8/34.6; PCB-156 1.22/1.05/1.10; PCB-180 27.6/24.8/23.0; PCB-194 4.91/5.42/6.19; ∑PCB5 83.9/77.6/72.3.

35.

During 1998-1999, blood samples from 26 polar bears (13 females and 13 males) from Svalbard, Norway and 30 male polar bears from Churchill, Canada were analyzed for organochlorines (Lie et al., 2004). The mean levels (ng/g wet wt) of ∑PCBs in female and male bears from Svalbard were 45.0 and 53.7, respectively, which did not differ significantly between genders. The mean level of ∑PCBs in the male bears from Canada was 42.5. The mean levels of ∑PCBs did not differ significantly between locations. In Svalbard bears, the mean level of ∑OCPs in female bears was 15.5, which was significantly higher the mean level of 6.8 in male bears. The mean level of ∑OCPs in the males from Canada was 16.1, which was significantly higher than the level in males from Svalbard. For all 56 bears, ∑PCBs and ∑OCPs were significantly positively correlated.

36.

Persistent organochlorine contaminants were determined in adipose tissue of 92 polar bears sampled between 1999-2001 in central East Greenland (Dietz et al., 2004). The following are the mean organochlorine concentrations (ng/g lipid wt) in the polar bears listed as (subadult N=50/adult females N=25/adult males N=16): ∑PCB 6470/8240/9100; ∑CBz 158/100/187; ∑HCH 198/263/218; ∑DDT 462/462/559; ∑Chlordanes 2010/2220/1710; mirex 4.08/2.79/6.59; dieldrin 218/208/245. When the present data was compared to concentrations reported in samples from 1990 from the same region, ∑CB, DDE, and ∑HCH concentrations in 1999-2001 were 22.1%,66.3% and 39.3% lower than the 1990 concentrations, respectively. In contrast, ∑ Chlordanes and dieldrin concentrations showed differences amongst sex and age groups where present concentrations are between 24.4% to 69.3% and 27.0% to 69% lower, respectively, relative to the 1990 levels.

37.

Organochlorine concentrations were determined in the whole blood and adipose tissue of male (n=7) and female (n=12) polar bears of random age (3-25 years) collected between 1999-2001 from central East Greenland (Sandala et al., 2004). The following are the arithmetic mean concentrations (N=19) listed as (adipose, ng/g lipid wt/whole blood, ng/g wet wt/whole blood, ng/g lipid wt): ∑-PCB 7020/46.1/6754; ∑-MeSO2-PCB 699/8.4/1230; ∑-CHL 1891/8.2/1192; ∑-DDT 496/3.0/375; ∑-CIBz 65/0.3/44; ∑-HCH 271/1.2/176; DDE 467/2.4/268; 3-MeSO2-DDE 16/0.2/26; ∑-Mirex 3/0.5/84; Dieldrin 233/<0.05/<0.1; OCS 24/0.1/18; ∑-HO-PCB not analyzed (n.a.)/182.3/25760; Pentachlorophenol n.a./0.3/51; 4-HO-heptachlorostyrene n.a./7.5/1151. There were no significant differences between males and females for the individual or sum concentrations of all the contaminant classes. 

38.

Adipose tissue from male (N=6) and female (N=3) polar bears (>5 years old) from the Svalbard area was used to analyze toxaphene concentrations (Føreid et al., 2000). The following are the average concentrations (ng/g fat wt) listed as (male/female): CHB-26 17/5.7; CHB-50 27/3.3; CHB-62 4.1/0.4.

39.

Samples of polar bear livers (N=5) were collected from the tissues archived by the U.S. Fish and Wildlife Service, Anchorage, AK, and analyzed for organochlorines (Corsolini et al., 2002). The mean concentrations (pg/g wet wt) for ∑PCNs, HCB, DDE, and ∑PCBs were 370, 16, 13, and 2110, respectively.

40.

PBDE concentrations were analyzed in polar bears captured in the Arctic (Wolkers et al., 2004). The following are the mean concentrations (ng/g lipid wt) listed as (male (N=10)/female (N=10): 4-BDE d (n.d./n.d.); 4-BDE 47 (27.4/45.6); 4-BDE 66 (n.d./n.d.); 5-BDE 85 (n.d./n.d.); 5-BDE 99 (n.d./n.d.); 5-BDE 100 (n.d./n.d.); 6-BDE 154 (n.d./n.d.); 4-BDE-O-ME a (n.d./n.d.); ∑PBDE (27.4/45.6).

II.

Cholinesterase-Inhibiting Pesticides

 

No data available

III.

Trace Elements, Metals, and Metalloids

1.

Fresh (1977-1980) and preserved (museum) (1910-1927) polar bear hair samples taken from polar bears across the Canadian Arctic were analyzed for Hg (Eaton and Farant, 1982). Mean total Hg (µg/g) from the fresh samples are as follows, listed by location: Amundsen Gulf (N=6), 18.54; Cornwallis Island (N=7), 7.85; North Baffin Island (N=27), 6.93; Clyde River (N=9), 4.92; South Baffin Island (N=13), 3.53; Southern shore of Hudson Bay, (N=41), 2.54. Hg concentrations from the museum specimens (N=18) are listed by location as (age/total Hg/inorganic Hg/organic Hg): Fort Churchill: (adult/2.8/0.7/2.1); Clinton Point: (adult/6.4/3.9/2.5); Cape Kellett, Banks I.: (<1 yr./5.1/2.2/2.9), (adult/4.0/2.4/1.6); Cape Bathurst: (adult/6.9/2.7/4.2), (juvenile/12.1/7.4/4.7), (juvenile/13.1/10.1/3.0), (adult/5.2/3.5/1.7), (adult/12.4/6.0/6.4), (adult/10.0/6.3/4.7), (adult/21.1/16.6/4.5), (adult/10.9/4.9/6.0), (juvenile/53.6/53.3/0.3), (juvenile/11.1/6.6/4.5); Smith Sound, Ellesmere I.: (adult/2.6/2.0/0.6); Cape Mercy, Baffin I.: (juvenile/2.0/1.4/0.6); Davis Strait: (cub-of-yr/1.5/0.9/0.6), (cub-of-yr/3.4/1.9/1.5). There was a geographic distribution showing higher levels in the western Arctic and lower levels in the eastern Arctic and in Hudson’s Bay for both fresh and museum specimens.

2.

Alaskan polar bear muscle and liver samples collected in 1972 were analyzed for total Hg (Lentfer and Galster, 1987). The following are the mean concentrations (µg/g wet wt) listed by tissue: Muscle (Western area, young, N=12 / Northern area, young, N=19 / Western area, adult, N=4 / Northern area, adult, N=11): 0.04 / 0.15 / 0.04 / 0.19; Liver (Western area, young, N=16 / Northern area, young, N=22 / Western area, adult, N=9 / Northern area, adult, N=15): 3.92 / 22.35 / 4.80 / 38.08. Bears north of Alaska had more Hg than bears west of Alaska, and the only difference between young and adult animals was in the northern area where adults had more Hg in liver tissue than young.

3.

A total of 141 polar bear hair samples, collected from five Arctic areas during 1976-1988, were analyzed for estimation of Hg content (Renzoni and Norstrom, 1990). The five localities are: A, western Hudson Bay, 1988, N=22; B, Beaufort Sea to Barrow Strait, 1982, N=55; C, Wrangel Island, 1984-1986, N=10; D, Svalbard archipelago, 1988, N=31; E, Lena river delta, 1984-1985, N=3. The material from the Beaufort Sea shows the greatest concentrations (µg/g) of Hg residues, while the material from the River Lena shows the lowest levels. Stations A and B were compared according to age and sex. The following is for station A: male adults, N=12, 3.12; male juveniles, N=6, 2.57; female adults, N=20, 2.97; female juveniles, N=4, 3.11. The following is for station B: male, N=35, 8.99; female, N=20, 10.22.

4.

Concentrations of total Hg were determined in hair of polar bears from captured from northwestern Greenland during 1978-1989, eastern Greenland during 1984-1989, and Svalbard during 1980 (Born et al., 1991). The following are the mean concentrations (µg/g dry wt) listed by location: Thule: (yearling, N=1 / 2 years and older, N=21) 9.51 / 8.38; Scoresby Sound (yearlings, N=3 / 2 years and older, N=37): 1.81/ 4.62; Ammassalik (2 years and older, N=4): 4.21; Svalbard (cub of the year, N=1 / yearling, N=1 / 2 years and older, N=29): 0.34 / 1.04 / 1.98. Concentrations of total Hg in hair were not found to be dependent on age or sex, however, there was a decreasing trend in Hg concentrations found from west to east.

5.

Samples of liver, kidney, and subcutaneous fat from 24 polar bears from Svalbard area during 1978-1989 were analyzed for some heavy metals and essential elements (Norheim et al., 1992). The following are the mean concentrations (µg/g wet wt) listed as (adult liver, N=16/juvenile(<2 yrs), N=6/adult kidney, N=7/juvenile kidney, N=3): Hg 2.6/1.9/4.9/1.9; Cd 0.6/0.3/8.1/3.8; Pb 0.5/<0.5/0.6/1.0; Cu 42/33/8.3/6.2; Zn 62/58/36/30; Se 2.4/2.0/4.6/2.5; As 0.06/0.04/0.04/0.03.

6.

Polar bear livers (N=67) from six zones in the western and central Canadian Arctic in 1982 were analyzed for 22 elements (Norstrom et al., 1986). The following are the mean concentrations (μg/g, wet wt): Ag 0.17; Al 0.23; As 0.07; Ba 0.02; Be 0.002; Ca 35.5; Cd 0.61; Co 0.3; Cr 0.10; Cu 38.6; Fe 168; Hg 30.1; K 2977; Mg 201; Mn 3.63; Mo 1; Na 844; Ni 0.3; P 3206; Se 10.0; Si 0.3-2.3; Sr 0.005-0.023; Th 0.05; Ti 0.02; V 0.07; Zn 62.4; Zr 0.3. Cd, Hg and Se had statistically significant effects for age and geographical location. Average levels of Cd were significantly higher in the eastern zones, while Hg levels tended to be higher in the western zones bordering the Beaufort Sea.

7.

Muscle, liver, and kidney tissues from 38 polar bears caught in the Scoresby Sound area, Central East Greenland, between 1983-1987 were analyzed for Zn, Cd, Hg, and Se (Dietz et al., 1995). Sample size (N) was divided by tissue and age: Muscle: 1 yr=1, 2-6 yrs=12, ≥7 yrs=5, all=18 (for Se, 1 yr=0 and all=17); Liver and Kidney: 1 yr=3, 2-6 yrs=20, ≥7 yrs=15, all=38. The following are the mean concentrations (µg/g, wet wt) listed by element and age as (muscle/liver/kidney): Zn: 1 yr (70.2/37.7/19.7), 2-6 yrs (59.3/56.5/33.8), ≥7 yrs (62.7/49.8/40.5), all (60.8/52.1/34.8); Cd:1 yr (0.019/0.233/2.17), 2-6 yrs (0.016/0.897/10.8), ≥7 yrs (0.048/0.998/24.4), all (0.022/0.841/13.1); Hg: 1 yr (0.101/1.81/2.87), 2-6 yrs (0.065/7.42/11.5), ≥7 yrs (0.082/11.4/30.8), all (0.071/7.87/15.2); Se: 1 yr (-/1.09/2.34), 2-6 yrs (0.313/3.26/6.25), ≥7 yrs (0.240/4.54/6.63), all (0.289/3.40/5.92). Hg and Cd were positively correlated with age in liver and kidney. Zn was positively correlated with age in kidney and Se was correlated with age in liver.

8.

Muscle, liver, and kidney tissues from 100 polar bears, caught during 1983-1990 in the Avanersuaq area, north-west Greenland, and Ittoqqortoormiit area, central-east Greenland, were analyzed for Zn, Cd, Hg, and Se (Dietz et al., 2000). The following are the mean concentrations (µg/g wet wt) listed by place as (muscle/liver/kidney): Zn: Avanersuaq, North: 2-6 yrs, N=14/12/13, (53.9/53.5/30.8); ≥7 yrs, N=3/3/3, (66.6/55.0/30.3); Avanersuaq, South: 1 yr, N=6/6/6, (49.9/53.1/31.1); 2-6 yrs, N=16/14/16, (52.6/64.8/35.9); ≥7 yrs, N=5/5/5, (58.6/55.2/34.3); Ittoqqortoormiit, North: 1 yr, N=1/1/1, (76.0/44.9/25.8); 2-6 yrs, N=7/8/9, (67.4/47.1/26.8); ≥7 yrs, N=5/8/8, (63.5/67.6/33.9); Ittoqqortoormiit, South: 1 yr, N=1/4/3, (70.2/42.9/19.7); 2-6 yrs, N=13/19/18, (58.6/58.0/35.0); ≥7 yrs, N=5/13/13, (62.7/48.1/41.0). Cd: Avanersuaq, North: 2-6 yrs, (<0.015/1.15/11.2); ≥7 yrs, (0.019/1.26/15.0); Avanersuaq, South: 1 yr, (<0.015/0.605/8.43); 2-6 yrs, (<0.015/1.68/17.0); ≥7 yrs, (0.027/1.98/23.3); Ittoqqortoormiit, North: 1 yr, (<0.015/0.120/2.43); 2-6 yrs, (<0.015/0.223/4.06); ≥7 yrs, (<0.015/0.442/9.07); Ittoqqortoormiit, South: 1 yr, (0.019/0.287/2.16); 2-6 yrs, (0.016/1.12/12.5); ≥7 yrs, (0.048/1.18/28.9). Hg: Avanersuaq, North: 2-6 yrs, (0.076/12.4/10.7); ≥7 yrs, (0.135/21.0/12.7); Avanersuaq, South: 1 yr, (0.082/4.25/4.22); 2-6 yrs, (0.034/12.9/12.6); ≥7 yrs, (0.034/22.0/28.1); Ittoqqortoormiit, North: 1 yr, (0.191/2.99/4.87); 2-6 yrs, (0.102/7.09/12.7); ≥7 yrs, (0.071/6.68/13.8); Ittoqqortoormiit, South: 1 yr, (0.101/2.13/2.87); 2-6 yrs, (0.064/7.52/11.2); ≥7 yrs, (0.082/13.4/32.0). Se: Avanersuaq, North: 2-6 yrs, (0.425/5.26/7.05); ≥7 yrs, (0.452/8.02/8.49); Avanersuaq, South: 1 yr, (0.341/2.16/4.49); 2-6 yrs, (0.426/6.42/7.70); ≥7 yrs, (0.399/9.80/13.9); Ittoqqortoormiit, North: 1 yr, (<0.2/1.64/3.25); 2-6 yrs, (0.244/2.98/4.98); ≥7 yrs, (<0.2/2.64/5.64); Ittoqqortoormiit, South: 1 yr, (-/1.20/2.34); 2-6 yrs, (0.319/3.27/6.78); ≥7 yrs, (0.240/5.16/6.53). Cd and Hg clearly accumulated with age, while Se had a weak increase with age. In central-east Greenland, Cd, Se, and some Hg concentrations in polar bears from the southern area were higher than from the northern area.

9.

Levels of metals were determined in livers of polar bears collected in 1984 in six zones in the Lancaster Sound, Baffin Bay and Hudson Bay areas of the Northwest Territories of Canada (Braune et al., 1991). The following are the mean concentrations (mg/kg dry wt) listed by zones as (western Arctic: H1, N=7/H2, N=8/G, N=8/E1, N=7; central Arctic: E2, N=14/F1, N=22; eastern Arctic, Baffin Bay and Hudson Bay: F2, N=8/D1, N=10/D2, N=9/D3, N=11/C, N=10/A1, N=10): Ag 0.43/0.40/0.26/0.36; 0.54/0.46; 0.51/0.48/0.38/0.49/0.21/0.21;

Ca 82/109/107/112; 98/101; 136/125/134/136/161/129;

Cd 1.22/1.03/0.60/0.58; 1.82/2.37; 3.96/3.13/4.57/3.85/2.70/3.33;             

Cu 102/120/85/81; 116/83; 114/109/126/146/94/121;

Fe 344/305/274/489; 404/319; 846/476/359/448/464/417;

Hg 122.5/99.8/200.3/58.9; 64.2/66.9; 84.2/43.4/21.9/53.2/18.5/20.0;

K 7124/8101/8349/8294; 8633/8789; 9263/8664/9765/9244/8587/8147;

Mg 481/555/579/599; 587/609; 671/676/711/666/599/595;

Mn 12.0/9.6/9.9/8.2; 10.0/10.4; 10.9/13.8/12.1/14.0/10.7/12.0;

Na 1535/2527/2379/3227; 2173/2373; 3155/3230/2720/2661/3330/2806;

P 8541/8848/9203/9749; 9354/9688; 10716/10532/11658/10873/10747/10120;

Se 54.1/32.7/63.4/23.6; 21.9/24.9; 26.6/14.5/9.7/19.4/3.9/4.7;

Zn 172/188/141/142; 176/176; 205/205/211/221/178/180.

Only levels of Cu, K, and Zn were found to have no statistically significant differences among zones. Levels of Cd, Hg, and Se were positively correlated with age, whereas K, Mn, Mg, and P were negatively correlated with age. Fe was significantly higher in females than in males.                                                                                 

10.

Concentrations of total and organic Hg were analyzed for polar bears collected from Greenland between 1984-1987 (Dietz et al., 1990). The following are the total and organic Hg concentrations (µg/g wet wt) found in 4 polar bears listed as (muscle, total/muscle, organic/liver, total/liver, organic/kidney, total/kidney, organic): M, subadult (101/66.3/2839/429/3754/217); M, adult (93/61.7/14572/418/12343/217); M, adult (-/-/4784/590/13823/206); F, old (89/48.2/23864/403/48606/136). Organic Hg mean concentrations in the muscle, liver, kidney of 3 polar bears are 58, 454 and 164, respectively.

11.

Polar bears from Greenland were captured between 1984-1990 and analyzed for metal concentrations (Dietz et al., 1996). The following are the mean concentrations (µg/g wet wt) listed as (tissue/N/Cd/Hg/Se): Northwest Greenland: (liver/28/1.46/12.6/5.87), (kidney/31/14.3/10.8/7.21), (muscle/33/<0.020/0.056/0.43), (liver/8/1.67/21.6/9.09), (kidney/8/19.7/20.9/11.6), (muscle/8/0.024/0.057/0.42); Central East Greenland: (liver/28/0.651/7.16/3.11), (kidney/28/8.22/11.3/5.98), (muscle/21/<0.020/0.080/0.29), (liver/21/0.812/10.3/4.00), (kidney/21/18.6/23.2/6.18), (muscle/10/0.023/0.078/<0.20).

12.

Bone tissue from 78 polar bears from the Canadian Northwest Territories was analyzed for various elements (Golovkin et al., 1991). The following are the mean concentrations (in conventional units) for 4 groups (grouped by location) listed as (group 1, N=6/ group 2, N=37/ group 3, N=23/ group 4, N=12): P 1.36/1.55/1.52/1.48; Ca 112/119/119/115; Fe 0.59/0.7/0.74/0.51; Zn 4.30/4.76/5.35/5.5; Sr 49/39/47/57.

13.

Tissue samples from polar bears captured from the region of Lancaster Sound between 1988-1990 were analyzed for total Hg (Atwell et al., 1998). The mean Hg concentration for 5 bears was 0.84 µg/g (dry wt).

14.

Concentrations of twelve essential and non-essential elements were evaluated in tissues of polar bears of arctic Alaska (USA) collected between 1995-1997 (Woshner et al., 2001). Concentrations (µg/g wet wt) in the liver (N=24) are as follows: As 0.09, Cd 0.47, Cu 30.0, Pb 0.08, Mg 371.0, Mn 5.13, Se 9.33, Ag 0.17, Zn 78.64, HgII 13.21, MHg 0.49, total Hg 14.22. Concentrations in the kidney (N=24) are as follows: As 0.02, Cd 8.69, Cu 3.39, Pb 0.29, Mg 247.0, Mn 1.80, Se 12.99, Ag 0.01, Zn 39.60, HgII not analyzed (n.a.), MHg n.a., ΣHg n.a.. Concentrations in the muscle (N=23) are as follows: As ND (N=18), Cd 0.01 (N=18), Cu 2.97, Pb 0.02, Mg 495.3, Mn 0.28, Se 0.54, Ag ND (N=18), Zn 64.08, HgII 0.03, MHg 0.07, SHg 0.09. Concentrations in the blubber (N=11) are as follows: As 0.07, Cd ND, Cu 0.27 (N=14), Pb ND (N=14), Mg 27.49 (N=14), Mn 0.05, Se 0.04, Ag 0.01, Zn 1.96 (N=14), HgII NA, MHg NA, SHg NA.

IV.

Petroleum

 

No data available

V.

Other

1.

Liver tissues of 17 polar bears from Alaska were collected during the 1990s to be analyzed for perfluorooctane sulfonate (PFOS) (Giesy and Kannan, 2001). The mean concentration of PFOS in the 17 polar bear liver tissues is 350 ng/g (wet wt).

 

 Polar Bear Contaminant Response Data

I.

Organochlorine Contaminants

 

Concentrations of PCBs, thyroid hormones (THs), and retinol were determined in two groups of female polar bears, females with cubs of the year (FWCOY) and females without cubs of the year (FWOCOY), and within a group of male polar bears collected from Svalbard, Norway between 1997-1998 (Braathen et al., 2004).  The following are the mean concentrations of THs (nmol/L) and retinol (µg/L) in the plasma of the polar bears listed as (FWCOY/FWOCOY/Males): Total T4 N=9, 15.3/N=30,18.5/N=22,13.5; Free T4 N=11, 4.38/N=28, 5.20/N=23, 3.46; Total T3 N=14, 1.26/N=28, 1.58/N=21, 1.23; Free T3 N=6, 1.26/N=16, 1.42/N=11, 0.95; Retinol N=17, 181/N=22, 201/N=15, 183.  PCBs did not affect the retinol status in any of the three groups. PCBs affected five TH variables in the female polar bears (Total T4, Free T4, Free T3,Total T3:FT3, Total T4:Total T3), while they affected only two TH variables in males (Free T3, Free T4:Free T3).

II.

Cholinesterase-Inhibiting Pesticides

 

No response data available

III.

Trace Elements, Metals, and Metalloids

 

No response data available

IV.

Petroleum

1.

Three sub-adult polar bears that were captured as nuisance bears in the area of Churchill, Manitoba in 1979 were immersed in a mixture of sea water and oil to determine body temperature, metabolism, and whole body thermal conductance before and after oil exposure (Hurst et al., 1991). Prior to oil exposure, grooming averaged 5% of the study animals’ time, but in the first 6 h following oil exposure increased to 42%. Within 8 h of exposure, violent shivering occurred in all 3 bears and continued for 36 more hours. Metabolism measured after oil exposure showed a significant average increase of 57% over pre-oil values. The following are the temperatures (°C) determined for the bears listed as (before oil contact/after oil contact): body temperature: bear 2 (36.9/36.9), bear 3 (36.8/35.8), bear 4 (36.6/36.7), mean (36.8/36.5); skin temperature: bear 2 (36.4/37.3), bear 3 (34.9/35.7), bear 4 (32.9/34.0), mean (34.7/35.7); whole body thermal conductance: bear 1 (1.55/1.86), bear 2 (2.22/3.08), bear 3 (1.56/2.50). There was a significant increase in skin temperature for all animals following oil exposure with an average increment of 0.96 °C.

2.

Three young polar bears that had been trapped as nuisance animals in the Churchill area in 1980 were immersed in a mixture of sea water and crude oil and subjected to a wind tunnel to simulate Arctic conditions, in order to test the physiological effects of a simulated oil slick on polar bears in view of the possibility of an oil spill due to explorations and drilling operations in the north (Crawshaw, 1980). The polar bears were washed 17 days later, but subsequently became anorectic and progressively more depressed. One male bear died 25 days after immersion. A second male bear, which exhibited severe depression and head tremors, had euthanasia performed on it. The third bear, a two-year-old female, was anesthetized to examine 33 days after immersion after she had not eaten for 20 days and was exceptionally docile. Examination revealed that the bear was extremely thin (180 lbs.), dehydrated, and anemic. The coat was in poor condition. There was no evidence of neurological disorder and temperature, pulse and respiration were normal. Urine was passes in small quantities and was dark and contained blood and a little protein. Blood samples confirmed the presence of anemia and gave evidence of renal failure with associated serum electrolyte abnormalities and some liver dysfunction. Symptoms gradually alleviated. After many more times of being anesthetized and worked on, she began to slowly start drinking again and eaten again. She had problems with abscesses opening and weakness in her legs, but eventually overcame this as well. About six months after the oil immersion, the bear was recovered and appeared to be in excellent condition, weighing 411 lbs.

3.

Fur samples from the mid-back region were obtained from 3 subadult polar bears taken during October in northern Canada to examine the effect of different oils on the insulation of polar bear fur in air (Hurst and Øritsland, 1982). Heat transfer regressions for seven polar bear pelt samples prior to oiling had an average of 1.67 heat transfer/meter2 (W.m-2.oC-1) for the calm air conductance. Values obtained the day of oiling were much higher. Under summer conditions, the heat transfer decreased as oil “melted” from the fur and physical matting of the pelt surface decreased. Under colder conditions, the physical coating changed very little with time. On the day of oiling, the calm air conductance averaged 3.67 times higher than controls. The mean calm air conductance following oil contact was 5.36 W.m-2.oC-1, representing an increase of 220% over control furs. Conductance was highest for furs treated with the viscous Base 2500 oil at 7.48 W.m-2.oC-1, followed by Midale and 10W oils at 4.61 and 4.01 W.m-2.oC-1, respectively. The wind coefficient averaged 0.13 prior to oiling, increasing substantially after exposure to an average of 0.51. The solar utilization factor averaged 0.11 prior to oiling, increasing in all cases after exposure to an average of 0.17.

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