Ross J. Norstrom

Organochlorine contaminants in arctic marine food chains: accumulation of specific polychlorinated biphenyls and chlordane-related compounds

Polychlorinated biphenyl congeners (S-PCB) and chlordane-related compounds (S-CHLOR) as well as DDT, hexachlorocyclohexane, toxaphene, and chlorobenzenes were determined in pooled arctic cod (Boreogadus saida) muscle and polar bear (Ursus maritimus) fat and in the blubber and liver of 59 ringed seals (Phoca hispida) from the east-central Canadian Arctic. S-PCB concentrations ranged from 0.0037 mg/kg (wet wt) in cod muscle to 0.68 mg/kg in male seal blubber and 4.50 mg/kg in bear fat. Tri- and tetrachloro PCB homologues were the dominant PCBs in fish, while pentachloro/hexachloro and hexachloro/heptachloro congeners predominated in ringed seal blubber and polar bear fat, respectively. Chlordane compounds detected in seal blubber were oxychlordane, cis- and trans-nonachlor, and cis-chlordane as well as nine minor components of technical chlordane, including nonachlor-III (a nonachlor isomer). Toxaphene and HCH isomers were the major organochlorines in cod muscle with mean concentrations of 0.018 and 0.010 mg/kg, respectively. S-CHLOR/S-PCB ratios ranged from 0.6 in fish muscle and bear fat to 0.7-0.9 in seal blubber, much higher than observed in more southerly marine environments, suggesting a proportionally greater input of chlordane into the Arctic.

Arctic marine ecosystem contamination

The current state of knowledge of levels, spatial and temporal trends of contaminants in the Arctic marine ecosystem varies greatly among pollutants and among environmental compartments. Levels of polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and some heavy metals such as mercury and lead, in Arctic marine mammals and fish are relatively well documented because of the need for comparisons with biota in more polluted environments and interest in the contamination of native diets. Levels of heavy metals, alkanes, polyaromatic hydrocarbons (PAH) and OCs in the Arctic Ocean are comparable to uncontaminated ocean waters in the mid-latitudes. But concentrations of alpha- and gamma-hexachlorocyclohexane (HCHs) are higher in northern waters far removed from local sources, possibly because lower water temperature reduces transfer to the atmosphere. Bioaccumulation of OCs and heavy metals in Arctic marine food chains begins with epontic ice algae or phytoplankton in surface waters. Polychlorinated camphenes (PCC), PCBs, DDT- and chlordane-related compounds are the major OCs in marine fish, mammals and seabirds. Mean concentrations of most PCBs and OC pesticides in ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic are quite similar indicating a uniform geographic distribution of contamination, although alpha-HCH showed a distinct latitudinal gradient in bears due to higher levels in zones influenced by continental runoff. Ringed seals from Spitzbergen have higher levels of PCBs, total DDT and polychlorinated dioxins/furans (PCDD/PCDFs). In contrast to other OCs, PCDD/PCDFs in Canadian Arctic ringed seals and polar bears were higher in the east/central Arctic than at more southerly locations. Remarkably high cadmium levels are found in kidney and liver of narwhal (Monodons monoceros) from western Baffin Bay (mean of 63.5 micrograms g-1) and western Greenland waters (median of 39.5 micrograms g-1). Mercury concentrations in muscle of ringed seal and cetaceans frequently exceed 0.5 microgram g-1 especially in older animals. Cadmium concentrations in polar bear liver increased from west to east, while mercury levels were higher in ringed seals from the western Canadian Arctic, which suggests that natural sources of these metals predominate. Studies of temporal trends in OCs in ringed seals and seabirds in the Canadian Arctic indicate PCB and DDT levels declined significantly from the early 1970s to the 1980s. There is a lack of temporal trend data for other OC pesticides as well as for heavy metals and hydrocarbons.(ABSTRACT TRUNCATED AT 400 WORDS)

Organochlorine contaminants in arctic marine food chains: identification, geographical distribution and temporal trends in polar bears.

Contamination of Canadian arctic and subarctic marine ecosystems by organochlorine (OC) compounds was measured by analysis of polar bear (Ursus maritimus) tissues collected from 12 zones between 1982 and 1984. PCB congeners (S-PCB), chlordanes, DDT and metabolites, chlorobenzenes (S-CBz), hexachlorocyclohexane isomers (S-HC-H), and dieldrin were identified by high-resolution gas chromatography-mass spectrometry. Nonachlor-III, a nonachlor isomer in technical chlordane, was positively identified for the first time as an environmental contaminant. S-PCB and S-CHLOR accounted for >80% of the total organochlorines in adipose tissue. Six PCB congeners constituted approximately 93% of S-PCB in polar bears. Levels of most OCs were lowest in the high Arctic, intermediate in Baffin Bay, and highest in Hudson Bay. Levels of ..cap alpha..-HCH were evaluated in zones influenced by surface runoff. Levels of S-CHLOR were four times higher and levels of the other OCs were two times higher in adipose tissue of bears from Hudson Bay and Baffin Bay in 1984 than in adipose tissue archived since 1969 from these areas; levels of S-DDT did not change.

Spatial and temporal trends and effects of contaminants in the Canadian Arctic marine ecosystem: a review

Recent studies have added substantially to our knowledge of spatial and temporal trends of persistent organic pollutants and heavy metals in the Canadian Arctic marine ecosystem. This paper reviews the current state of knowledge of contaminants in marine biota in the Canadian Arctic and where possible, discusses biological effects. The geographic coverage of information on contaminants such as persistent organochlorines (OCs) (PCBs, DDT- and chlordane-related compounds, hexachlorocyclohexanes, toxaphene) and heavy metals (mercury, selenium, cadmium, lead) in tissues of marine mammal and sea birds is relatively complete. All major beluga, ringed seal and polar bear stocks along with several major sea bird colonies have been sampled and analysed for OC and heavy metal contaminants. Studies on contaminants in walrus are limited to Foxe Basin and northern Québec stocks, while migratory harp seals have only been studied recently at one location. Contaminant measurements in bearded seal, harbour seal, bowhead whale and killer whale tissues from the Canadian Arctic are very limited or non-existent. Many of the temporal trend data for contaminants in Canadian Arctic biota are confounded by changes in analytical methodology, as well as by variability due to age/size, or to dietary and population shifts. Despite this, studies of OCs in ringed seal blubber at Holman Island and in sea birds at Prince Leopold Island in Lancaster Sound show declining concentrations of PCBs and DDT-related compounds from the 1970s to 1980s then a levelling off during the 1980s and early 1990s. For other OCs, such as chlordane, HCH and toxaphene, limited data for the 1980s to early 1990s suggests few significant declines in concentrations in marine mammals or sea birds. Temporal trend studies of heavy metals in ringed seals and beluga found higher mean concentrations of mercury in more recent (1993/1994) samples than in earlier collections (1981-1984 in eastern Arctic, 1972-1973 in western Arctic) for both species. Rates of accumulation of mercury are also higher in present day animals than 10-20 years ago. Cadmium concentrations in the same animals (eastern Arctic only) showed no change over a 10-year period. No temporal trend data are available for metals in sea birds or polar bears. There have been major advances in knowledge of specific biomarkers in Canadian Arctic biota over the past few years. The species with the most significant risk of exposure to PCBs and OC pesticides may be the polar bear which, based on comparison with EROD activity in other marine mammals (beluga, ringed seal), appears to have elevated CYP1A-mediated activity. The MFO enzyme data for polar bear, beluga and seals suggest that even the relatively low levels of contaminants present in Arctic animals may not be without biological effects, especially during years of poor feeding.

USING ANTHROPOGENIC CONTAMINANTS AND STABLE ISOTOPES TO ASSESS THE FEEDING ECOLOGY OF GREENLAND SHARKS

Organochlorine contaminants (OCs) are a large group of ubiquitous pollutants that have potential as tracers of ecological processes. To examine this utility, we measured OCs, stable isotopes of nitrogen (δ15N) and carbon (δ15C), and stomach contents in a large Arctic marine fish, the Greenland shark (Somniosus microcephalus), collected in the Davis Strait region to examine the feeding ecology of this little studied elasmobranch. Stable isotopes and OCs were also measured in the turbot (Reinhardtius hippoglossoides) and stable isotopes in the ringed seal (Phoca hispida) and harp seal (Pagophilus groenlandicus) to put the shark results in context. Values of δ15N suggest that the Greenland shark feeds at a similar trophic level as the turbot and ringed seal (about the fourth trophic level) and at a higher trophic level than harp seals, despite the presence of many turbot and a single ringed seal in the stomach contents of 14 sharks. Values of δ13C indicate that source of carbon in turbot and Greenland shark ...

Chlorinated hydrocarbon contaminants in arctic marine mammals

By 1976, the presence of chlorinated hydrocarbon contaminants (CHCs) had been demonstrated in fur seal (Callorhinus ursinus), ringed seal (Phoca hispida), hooded seal (Cystophora cristata), bearded seal (Erignathus barbatus), walrus (Obdobenus rosmarus divergens), beluga (Delphinapterus leucas), porpoise (Phocoena phocoena) and polar bear (Ursus maritimus) in various parts of the Arctic. In spite of this early interest, very little subsequent research on contaminants in Arctic marine mammals was undertaken until the mid-1980s. Since that time, there has been an explosion of interest, resulting in a much expanded data base on contaminants in Arctic marine mammals. Except in the Russian Arctic, data have now been obtained on the temporospatial distribution of PCBs and other contaminants in ringed seal, beluga and polar bear. Contaminants in narwhal (Monodon monoceros) have also now been measured. On a fat weight basis, the sum of DDT-related compounds (S-DDT) and PCB levels are lowest in walrus (< 0.1 microgram/g), followed by ringed seal, (0.1-1 microgram/g range). Levels are an order of magnitude higher in beluga and narwhal (1-10 micrograms/g range). It appears that metabolism and excretion of S-DDT and PCBs may be less efficient in cetaceans, leading to greater biomagnification. Polar bears have similar levels of PCBs as cetaceans (1-10 micrograms/g), but with a much simpler congener pattern. DDE levels are lowest in polar bear, indicating rapid metabolism. Effects of age and sex on residue levels are found for all species where this was measured. Among cetaceans and ringed seal, sexually mature females have lower levels than males due to lactation. Although PCB levels in adult male polar bears are about twice as high as females, there is only a trivial age effect in either sex apart from an initial decrease from birth to sexual maturity (age 0-5). Comparison of levels of S-DDT and PCBs in Arctic beluga and ringed seal with those in beluga in the Gulf of St. Lawrence and ringed seal in the Baltic Sea, indicate that overall contamination of the Arctic marine ecosystem is 10-50 times less than the most highly contaminated areas in the northern hemisphere temperate latitude marine environment. Geographic distribution of residue levels in polar bears indicates a gradual increase from Alaska east to Svalbard, except PCB levels are significantly higher in eastern Greenland and Svalbard. Information on temporal trends is somewhat contradictory.(ABSTRACT TRUNCATED AT 400 WORDS)

Toxic Compounds and Health and Reproductive Effects in St. Lawrence Beluga Whales

An epidemiologic study was carried out over a period of 9 years on an isolated population of beluga whales (Delphinapterus leucas) residing in the St. Lawrence estuary (Quebec, Canada). More than 100 individual deaths were aged, and/or autopsied and analyzed for toxic compounds, and the population was surveyed for size and structure. Arctic belugas and other species of whales and seals from the St. Lawrence were used for comparison. Population dynamics: Population size appeared to be stable and modeling showed this stable pattern to result from low calf production and/or low survival to adulthood. Toxicology: St. Lawrence belugas had higher or much higher levels of mercury, lead, PCBs, DDT, Mirex, benzo[a]pyrene metabolites, equivalent levels of dioxins, furans, and PAH metabolites, and much lower levels of cadmium than Arctic belugas. In other St. Lawrence cetaceans, levels of PCBs and DDT were inversely related to body size, as resulting from differences in metabolic rate, diet, and trophic position, compounded by length of residence in the St. Lawrence basin. St. Lawrence belugas had much higher levels than predicted from body size alone; levels increased with age in both sexes, although unloading by females through the placenta and/or lactation was evidenced by overall lower levels in females and very high burdens in some calves. No PCDDs and only low levels of some PCDFs were detected in St. Lawrence belugas, while proportions of toxic non-ortho (coplanar) PCBs were low relative to proportions seen in other species. At least ten different PCB methylsulphone metabolites were detected in St. Lawrence belugas. Levels of B[a]P adducts to DNA in St. Lawrence beluga brain and liver approached those associated with carcinogenis in small laboratory animals. Pathology: St. Lawrence belugas were not emaciated, and major findings were: a high prevalence of tumors (40% of animals) including eight malignant neoplasms; a high incidence of lesions to the digestive system (53%), to the mammary glands (45% of adult females), and to other glandular structures (11%); some evidence of immuno-suppression; frequent tooth loss and periodontitis. Two animals had severe ankylosing spondylosis and another was a true bilateral hermaphrodite. No such lesions were observed in 36 necropsies of Arctic belugas and of seals and cetaceans from the St. Lawrence.

Organochlorine chemical and heavy metal contaminants in white-beaked dolphins (Lagenorhynchus albirostris) and pilot whales (Globicephala melaena) from the coast of Newfoundland, Canada

Polychlorinated biphenyls (∑PCB), DDT isomers (∑DDT), chlordanes (∑CHLOR), toxaphene, chlorobenzenes and hexachlorocyclohexane isomers and seven elements (As, Cd, Cu, Hg, Pb, Se, Zn) were determined in tissues of 41 stranded pilot whales (Globicephala melaena) and 27 ice-entrapped white-beaked dolphins (Lagenorhynchus albirostris) from Newfoundland, Canada. Cadmium, Hg, As and Se were significantly higher in pilot whale kidney and liver than in dolphin tissues. Mercury in liver and blubber, and Cd in kidney, of pilot whales were positively correlated with age. Cadmium levels in both species were much higher than reported for other cetaceans from Canadian east coast waters. Lead concentrations in dolphin kidney and mucles were 5 times higher than in pilot whales. Levels of ∑PCB (sum of 49 congeners) in blubber samples ranged from 31 to 61 mg/kg (lipid wt) in female and male dolphins, respectively, and from 5.6 to 12 mg/kg in female and male pilot whales. ∑DDT and toxaphene were present at similar levels to ∑PCB while mean ∑CHLOR (sum of seven components) ranged from 1.6 to 17 mg/kg in blubber of pilot whales and dolphins, respectively. The presence of high levels of toxaphene in the blubber of both species was unexpected and may be due to increased use of this pesticide during the 1970s. Higher levels of all organochlorine chemicals in blubber, as well as Pb in kidney and muscle, of dolphins than in pilot whales may reflect greater exposure to contaminants because of overwintering and feeding in Gulf of St. Lawrence waters.

The case for a cause‐effect linkage between environmental contamination and development in eggs of the common snapping turtle (Chelydra s.serpentina) from Ontario, Canada

Concentrations of polychlorinated biphenyls (PCBs), dibenzo-p-dioxins, and dibenzofurans, organochlorine pesticides, and their metabolites were measured in eggs of the common snapping turtle (Chelydra s.serpentina) collected from four wetlands on the shorelines of Lakes Ontario, and Erie, and one control location in central Ontario, Canada. Snapping turtle eggs from these sites were also artificially incubated to determine hatching success, and incidence of deformities in embryo and hatchling turtles. The hypothesis that elevated incidences of egg death and/or deformities of hatchling turtles would occur in populations with high concentrations of organochlorine contaminants in eggs was tested. The results were elevated using epidemiological criteria. Unhatched eggs and deformities occurred at significantly higher rates in eggs from Lake Ontario wetlands. Two of three sites from Lake Ontario had substantially higher levels of PCBs, dioxins, and furans compared to eggs from Lake Erie and the control site. It could not be shown that contamination of eggs preceded the occurrence of poor development of eggs, although excellent hatching success and low numbers of deformities in eggs from the control site were considered representative of development in healthy eggs. The statistical association between contaminant levels in eggs and poor development of these eggs supported the hypothesis that eggs from sites with the greatest contamination had the highest rates of abnormalities. PCBs were the most strongly associated chemicals, although possible effects due to the presence of other chemicals in eggs was a confounding factor. The deformities and rates of unhatched eggs were similar to those occurring in other vertebrates collected from highly contaminated areas of the Great Lakes. There were several chemicals present in the eggs that can cause similar reproductive effects in other species; therefore a specific chemical effect was not identified. Results were coherent with known statistical and biological information. Theoretical and factual evidence of PCB contamination in wild-caught snapping turtles supported and hypothesis. However, lack of controlled studies of reproductive effects of polychlorinated hydrocarbons upon this species hindered the agreement of all factual and theoretical evidence with the hypothesis.

Body burdens and tissue concentrations of organochlorines in polar bears (Ursus maritimus) vary during seasonal fasts.

Lipophilic organochlorines (OCs) are ingested by mammals through their foods and are generally stored in adipose tissue depots. For some species, such as polar bears, the size of these depots can fluctuate seasonally by several-fold. However, the effect of these fluctuations on the fate of stored OCs in an animal with such labile lipid depots is unknown. We determined the whole body burden and tissue concentrations of OCs in free-ranging polar bears categorized by age (cubs-of-the-year, yearlings and adults) and sex before and after a fast averaging 56 days. Adipose tissue, plasma, and milk samples were analysed for sum of chlorobenzenes (sigma-ClBzs), hexachlorocyclohexanes (sigma-HCHs), chlordanes (sigma-CHLORs), dichlorodiphenyltrichloroethane compounds (sigma-DDTs) and polychlorinated biphenyls (sigma-PCBs). Decline in body mass during fasting ranged from 0.2 kg/day for cubs-of-the-year to 0.9 kg/day for sub-adult and adult males. Although all bears showed a decline in both lipid and lean mass during fasting, patterns of OC whole body burden changes were not consistent among compounds and bear classes. The burdens of sigma-DDTs declined by 11-50% for most bears during fasting, those of sigma-CHLORs declined by 67% during fasting in sub-adult and adult males but remained constant for all females, indicating male-specific metabolism of sigma-CHLORs. As fat depots became depleted, OC concentrations in the remaining adipose tissue varied; sigma-DDTs and sigma-HCHs declined while those of sigma-CHLORs and sigma-PCBs generally increased. Thus. within a 3-4 month fast, most polar bears were able to significantly rid their adipose tissue of sigma-DDTs and sigma-HCHs. Burdens of sigma-CHLORs (except males), sigma-ClBzs and sigma-PCBs remained constant for all classes of bears, therefore there was no significant excretion or metabolism during the fast of the specific congeners in these compound classes typically found in polar bears. The ratio of plasma/adipose tissue and milk/adipose tissue OC concentrations was the same for before and after the fast indicating that OC concentrations in polar bears are probably at a steady state among various body compartments. Concentrations of sigma-CHLORs and sigma-PCBs in milk almost doubled during the fast. As a consequence of this rise in milk OC concentrations, the whole body concentrations of these compounds increased in nursing cubs. Since developing young may be susceptible to the effects of environmental contaminants, the increased exposure of nursing cubs to OCs during a fast by their mothers is noteworthy.