Biomedical subjects
Publications and source records attributed to R J Norstrom.
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Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were determined in pooled samples of ringed seal (Phoca hispida) blubber, beluga (Delphinapterus leucas) blubber and polar bear (Ursus maritimus) liver and fat from several areas throughout the Canadian north and compared to mean PCB and HCB levels in the same samples. All seal samples, and all but one polar bear sample, had detectable 2,3,7,8-TCDD at concentrations ranging from 2 to 37 ng/kg, but TCDD was not found in beluga blubber (< 2 ng/kg). All seal samples and one of three beluga samples contained 2,3,7,8-TCDF at levels of 2 to 7 ng/kg, but TCDF was not found in any bear sample. TCDF must therefore be cleared rapidly by polar bears. No other PCDF congeners were found at detection limits of 4 to 8 ng/kg. OCDD concentrations in seal blubber and polar bear samples ranged from not detected (< 8 ng/kg) to 43 ng/kg. No apparent biomagnification of TCDD, OCDD or TCDF occurred from seal to bear fat, similar to previous findings for DDT, and unlike SigmaPCBs and HCB which biomagnified 6- to 17-fold. Highest concentrations of 2,3,7,8-TCDD and OCDD in seals and bears were found in the central Canadian Arctic Archipelago, and lowest were found in Hudson Bay, the reverse of PCB concentration distribution. The reason for higher levels of TCDD and OCDD in the Arctic than in the sub-Arctic is suggested to be trans-polar movement of aerosols with combustion-related origins in Eurasia. Levels of 2,3,7,8-TCDF were more evenly distributed throughout the North, and were positively correlated with PCB, but not with HCB or 2,3,7,8-TCDD levels in seals.
As part of the Canadian Wildlife Service monitoring of great blue herons in British Columbia, eggs were collected from three colonies with low, intermediate, and high levels of PCDD and PCDF contamination: Nicomekl, Vancouver, and Crofton, respectively. One egg from each nest was used for chemical analysis by GC-MS; the others were hatched. Liver microsomes were prepared from the heron chicks and used for determination of cytochrome P-450-dependent activities. No erythromycin N-demethylase activity was found in any sample. Ethoxyresorufin O-dealkylase activity in the Nicomekl group was similar to that in pigeons, a control altricial species. The ethoxyresorufin activity in the herons from the Crofton colony was 2.6-fold higher than in the Nicomekl group. The Vancouver colony was intermediate. No difference among the three heron colonies was found in pentoxyresorufin O-dealkylase activity, although levels were 20-33 times that in the pigeon. Chemical analysis was carried out on paired heron eggs. Vancouver and Crofton eggs contained 13.5 and 21 times the levels of 2,3,7,8-TCDD compared to the Nicomekl group. The Crofton eggs contained higher levels of several other contaminants also. A highly significant correlation (p less than .001) was found between ethoxyresorufin O-dealkylase and 2,3,7,8-TCDD concentrations. The correlation coefficient did not change when ethoxyresorufin O-dealkylase was compared to total chemical contamination using several toxic equivalency factors. Multiple regression analysis resulted in only one predictor variable for ethoxyresorufin O-dealkylase: 2,3,7,8-TCDD.
Eggs of three seabird species, double-crested cormorant (Phalacrocorax auritus). Leach's storm-petrel (Oceanodroma leucorhoa), and Atlantic puffin (Fratercula arctica) were collected at four-year intervals from 1968 to 1984, from colonies in eastern Canada and analyzed for organochlorines. This monitoring study was established to provide data on contamination of the marine environment and possible implications for seabird health. Long-term trend data are presented for PCBs, DDE, dieldrin, HCB, oxychlordane, heptachlor epoxide, HCH and mirex. DDE and PCBs declined significantly in all species from the Bay of Fundy. DDE declined significantly in puffins and petrels while PCBs declined only in petrels from the Atlantic coast of Newfoundland. Generally DDE declined more than PCBs. Dieldrin, oxychlordane, HCH and mirex levels decreased at some locations but were stable at others. Hexachlorobenzene and heptachlor epoxide levels remained steady or increased significantly, depending on the species and location. Organochlorine levels in cormorants from the St. Lawrence River estuary showed no significant trends.
In 1986, eggs were collected and productivity estimated at four great blue heron (Ardea herodias) colonies on the coast of British Columbia. Polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were present in all eggs in a qualitatively similar pattern among colonies. PCDD levels were significantly elevated at a colony near a kraft pulp mill at Crofton on Vancouver Island, although there was no correlation between the number of young raised in a nest and levels of either PCDDs, PCDFs, PCBs, organochlorine pesticides or mercury. In 1987, heron productivity was normal at three colonies, while the colony at Crofton failed to raise any young. A normal complement of eggs were apparently laid in about 57 nests, but during incubation they were destroyed and the broken eggshells were found in and beneath the nests. Analysis of eggs salvaged from nests showed that 2378-TCDD levels were about three times higher in 1987 than in 1986. At a colony in Vancouver, 2378-TCDF levels were significantly higher in 1987 than 1986 eggs. Levels of organochlorine pesticides and total mercury in eggs were generally low; highest residue levels were found in two mainland colonies, particularly at one adjacent to an agricultural area. Total PCB levels were low and did not differ significantly among locations. Analysis of PCB congener ratios indicated different sources of PCBs. Regurgitated prey samples collected in 1986 from four locations had generally low levels of PCDD, PCDF, mercury, lead and cadmium contamination.
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The northern gannets (Sula bassanus) nesting on Bonaventure Island, Quebec, were studied from 1968 to 1984 in order to measure environmental contaminant levels and their relationship to productivity. Fresh eggs in 1969 contained a mean DDE level of 18.5 mg kg(-1) and had shells which were 17% thinner than pre-1947 samples. Unhatched eggs in 1969 had no outer calcified layer, a mean thickness 20% less than the pre-1947 mean, and mean DDE concentration of 30.6 mg kg(-1). Significantly higher levels of eight contaminants were measured in unhatched than in fresh eggs collected in 1969. DDE and shell thinning were also intercorrelated with nine other contaminants; these data strongly implicate toxic chemicals, particularly DDE, as the main cause for the low breeding success of Bonaventure gannets from 1966 to 1974. Extensive use of DDT to control forest insects around the Gulf of St Lawrence ceased in 1969. Use of DDT, dieldrin and PCBs was restricted in North America during the early 1970s. Residues of DDT, DDD, DDE, PCBs, dieldrin, HCB and chlordane-related compounds in gannet eggs decreased significantly during this study. Heptachlor epoxide remained constant while alpha-HCH appeared to increase. Estimated half-lives ranged from 3.1 years for DDD to 35.4 years for oxychlordane. The breeding success and population of the colony have coincidentally increased.
Polar bear (Ursus maritimus) livers (67) from six Management Zones in the western and central Canadian Arctic were analysed for 22 elements. Several, Ba, Be, Co, Mo, Ti, V and Zr, were near the detection limit in all cases. Baseline data were obtained for the remaining elements, Ag, As, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, P, Se, Sr and Zn. No statistically significant effect of age, sex or geographical location was found for any of the elements, except Cd, Hg and Se, for which age and geographical location effects were found. The frequency distribution of Zn levels was bimodal. The second peak in the distribution appeared to be related to elevated levels of Cu. The average level of Cu was 104 mg kg-1 (dry wt.), higher than other marine mammals. Average levels of Cd were significantly higher in the eastern zones, but were always less than 1.0 mg kg-1 (dry wt.), significantly lower than their prey species. This may be due to the preference of polar bears for eating seal skin and fat which is low in Cd. Mercury levels tended to be higher in the western zones bordering the Beaufort Sea, which may be related to a higher proportion of bearded seal in their diet. Mean Hg levels ranged from 20 mg kg-1 in the eastern zones were related to age by the expression: Hg (mg kg-1 dry wt.) = 15.7 + 8.0 Age (years). Mercury levels in the most northerly zone near Melville Island were very high: Hg (mg kg-1 dry wt.) = 18.4 + 27.5 Age (years). Levels of Hg and Se were very highly correlated, with a molar ratio of 1.27:1, Hg/Se.
Oral administration of Prudhoe Bay crude or Hibernia crude to nestling herring gulls increased the hepatic cytochrome P-450 content 4-fold. Concomitantly, there was an increase in various mixed-function oxidase and phase II enzyme activities. 7-Ethoxyresorufin O-deethylase was elevated 19-fold, benzo(a)pyrene 3-hydroxylase 6-fold, aniline hydroxylase 3-fold, and aminopyrine N-demethylase and uridine diphosphate glucuronyl transferase 2-fold. There was no change in reduced glutathione S-transferase activity. Renal mixed-function oxidase activities were also elevated. Herring gull livers contained very low levels of DT-diaphorase activity which was inducible 3- to 5-fold by oil administration.
In order to determine the extent to which organically-bound chlorine in Herring Gull eggs from Lake Ontario can be accounted for by gas chromatographic analysis, comparison was made with values obtained for total chlorine using instrumental neutron activation analysis (INAA). Total chlorine and bromine (mg/kg fresh weight of egg) was determined by INAA on crude extract (Cl, 65 +/- 35; Br, 1.03 +/- 1.00), Florisil-chromatography treated extracts (Cl, 46 +/- 10; Br, 0.93 +/- 0.82) and H2SO4-treated extracts (Cl, 43 +/- 11; Br, 0.44 +/- 0.22) of eggs collected from seven colonies around Lake Ontario in 1977. Levels of chlorine were also determined by gas chromatography using the Hall electrolytic conductivity detector (51 +/- 11 mg/kg) and estimated by conversion of levels of individual residues determined by electron-capture gas chromatography (61 +/- 12 mg/kg). The agreement between the various determinations indicated that PCBs, DDE, mirex and photomirex accounted for most of the organically-bound chlorine. Two colonies had total chlorine levels in crude extracts 2--4 times higher than could be accounted for by know compounds. The "excess" chlorine was removed by H2SO4-treatment or Florisil clean-up. The same two samples had abnormally high bromine levels, possibly indicating the presence of compounds formed during aqueous chlorination processes.
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Adult New Zealand white does were intubated orally with single daily doses of 0, 5, or 10 mg of photomirex (8-monohydromirex) per kg body weight from the 6th through to the 18th day of gestation. Pregnancies were interrupted at term by cesarian section and fetuses removed and evaluated by following routine teratologic methods. Both maternal and fetal tissues were analyzed for residues of photomirex. None of the treated does showed any sign of toxicity. Except for a significant reduction in the mean fetal weight of the 10 mg/kg group all other parameters which evaluated fetal survival and fetal development were within the control range. Photomirex was found in all tissues examined. In the doe, the highest levels were found in fat followed by liver, kidney, spleen, heart, brain and blood. Photomirex was readily transferred across the placenta and accumulated in the fetus. However, in the fetus the highest levels were found in the heart, followed by liver, brain and blood. There were no teratogenic effects at the doses used in this study.
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The metabolic behavior of pure mono-, di-, tetra-, and hexachlorobiphenyl isomers in pigeons, rats, and brook trout was investigated. Excreta from these animals were extracted and examined by chromatographic and mass spectrometric techniques. The results showed conversion of the 4-chloro-, 4,4'-dichloro-, and 2,2',5,5'-tetrachlorobiphenyl isomers into monohydroxylated derivatives by the rat and pigeon whereas no hydroxymetabolites were detected in the excreta of the brook trout. No hydroxylated products of 2,2',4,4',5,5'-hexachlorobiphenyl were detected in the excreta of pigeons, rats, or brook trout.
Samples of Calanus hyperboreus, a herbivorous copepod, were collected (n = 20) between April and July 1998, and water samples (n = 6) were collected in May 1998, in the Northwater Polynya (NOW) to examine persistent organic pollutants (POPs) in a high Arctic marine zooplankton. Lipid content (dry weight) doubled, water content (r2 = 0.88) and delta15N (r2 = 0.54) significantly decreased, and delta13C significantly increased (r2 = 0.30) in the C. hyperboreus over the collection period allowing an examination of the role of these variables in POP dynamics in this small pelagic zooplankton. The rank and concentrations of POP groups in C. hyperboreus over the entire sampling was sum of PCB (30.1 +/- 4.03 ng/g, dry weight) > sum of HCH (11.8 +/- 3.23) > sum of DDT (4.74 +/- 0.74), sum of CHLOR (4.44 +/- 1.0) > sum of CIBz (2.42 +/- 0.18), although these rankings varied considerably over the summer. The alpha- and gamma-HCH and lower chlorinated PCB congeners were the most common POPs in C. hyperboreus. The relationship between bioconcentration factor (BCF) and octanol-water partition coefficient (Kow) observed for the C. hyperboreus was linear and near 1:1 (slope = 0.72) for POPs with a log Kow between 3 and 6 but curvilinear when hydrophobic POPs (log Kow > 6) were included. Concentrations of sum of HCH. Sum of CHLOR and sum of CIBz increased over the sampling period, but no change in sum of PCB or sum of DDT was observed. After removing the effects of time, the variables lipid content, water content, delta15N and delta13C did not describe POP concentrations in C. hyperboreus. These results suggest that hydrophobic POP (log Kow = 3.86.0) concentrations in zooplankton are likely to reflect water concentrations and that POPs do not biomagnify in C. hyperboreus or likely in other small, herbivorous zooplankton.