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John E Elliott - One of the best experts on this subject based on the ideXlab platform.
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Chlorinated Hydrocarbon contaminants in feces of river otters from the southern pacific coast of canada 1998 2004
Science of The Total Environment, 2008Co-Authors: John E Elliott, Daniel A Guertin, Jennifer M E BalkeAbstract:Abstract Chlorinated Hydrocarbon contaminants in coastal river otters ( Lontra canadensis ) were evaluated by sampling feces (scats) collected on the south coast of British Columbia, Canada. A broad survey of industrialized areas of the Strait of Georgia region was conducted in 1998, and a subsequent survey of working harbours in 2004. Samples from 1998 were analyzed for polyChlorinated biphenyls (PCBs), organochlorine (OC) pesticides, and polyChlorinated dioxins (PCDDs) and furans (PCDFs), while in 2004, chemistry was confined to ∑PCBs and OC pesticides. Concentrations of OC pesticides were low in both years, with only dichlorodiphenyldichloroethylene (DDE; range: 0.01–2.12 mg/kg lw) and hexachlorocyclobenzene (HCB; range: 0.003–0.25 mg/kg lw) detected in all samples. In 1998, octachlorodibenzo- p -dioxin (OCDD) and other higher Chlorinated PCDD/Fs were found in most samples, with OCDD ranging from 120 ng/kg lw in Clayoquot Sound to 19,100 ng/kg lw in a pooled sample from two latrines in Nanaimo. PCBs were present in all samples. In 1998 geometric mean concentrations of the sum of 59 PCB congeners ranged from 0.49 mg/kg lw in Nanaimo to 12.3 mg/kg lw in Victoria Harbour. Six years later, mean ∑PCBs remained elevated (geometric mean 9.5 mg/kg lw) in Victoria Harbour. Geometric mean concentrations of ∑PCBs from Victoria Harbour in 1998 and 2004 were > 9 mg/kg lw, a published adverse effect level for reproduction. At some latrines in both Victoria and Esquimalt Harbours, concentrations of TCDD-toxic equivalents exceeded 1500 ng/kg lw, a value for health effects in otters that we derived using published information. As shown in previous studies, analysis of scats provides an efficient and non-intrusive approach to assessing contaminant threats to otter populations, and to documenting spatial trends in residues.
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Chlorinated Hydrocarbon contaminants and stable isotope ratios in pelagic seabirds from the north pacific ocean
Archives of Environmental Contamination and Toxicology, 2005Co-Authors: John E ElliottAbstract:Organochlorine pesticides, polyChlorinated biphenyls (PCBs), and stable isotopes of nitrogen (δ15N) and carbon (δ13C) were determined in livers of eight seabird species (Diomedea immutabilis, D. nigripes, Fulmarus glacialis, Puffinus bulleri, P. carneipes, P. griseus, P. tenuirostris, and Fratercula corniculata) collected opportunistically from an experimental fishery in the North Pacific Ocean. Concentrations of P, P′-DDE were found in all samples but were highly variable among species, ranging over >2 orders of magnitude from 1.23 mg/kg (wet weight) in D. nigripes to 0.008 mg/kg in P. tenuirostris, whereas total PCBs ranged from 1.14 to 0.020 mg/kg in those same two species. Residues of hexachlorobenzene, trans-nonachlor, photo-mirex, mirex, β-hexachlorocyclohexane, oxychlordane, and heptachlor expoxide were quantified at lower concentrations in all samples. There were significant positive regressions of lipid-normalized concentrations of DDE (r2 = 0.526), total PCBs (r2 = 0.566), CB-153 (r2 = 0.565), and mirex (r2 = 0.586) on the hepatic δ15N signature, indicating that trophic level accounted for approximately 50% of the variability in those contaminants among species. In some species, e.g., P. bulleri, concentrations were lower than expected based on δ15N, which was attributed to a dietary switch before sampling and therefore lack of concordance in the time scales integrated by hepatic Chlorinated Hydrocarbon concentrations compared with δ15N.
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assessing breeding potential of peregrine falcons based on Chlorinated Hydrocarbon concentrations in prey
Environmental Pollution, 2005Co-Authors: John E Elliott, M J R Miller, Laurie K WilsonAbstract:Peregrine falcons (Falco peregrinus) now breed successfully in most areas of North America from which they were previously extirpated. The loss during the mid-part of the last century of many of the world's peregrine populations was largely a consequence of impaired reproduction caused by the effects of DDE on eggshell quality and embryo hatchability. Population recovery has been attributed to re-introduction efforts, coupled with regulatory restrictions on the use of organochlorine pesticides. Peregrines have not returned to breed in some areas, such as the Okanagan Valley of British Columbia. That region has been extensively planted in fruit orchards which were treated annually with DDT during the early 1950s to the 1970s. Ongoing contamination of avian species, including potential peregrine prey, inhabiting orchards has been documented. In response to an initiative to release peregrines around the city of Kelowna in the Okanagan Valley, we collected potential peregrine prey species and analyzed whole bodies for Chlorinated Hydrocarbon residues. We used a simple bioaccumulation model to predict concentrations of DDE in peregrine eggs using concentrations in prey and estimates of dietary makeup as input. Peregrines would be expected to breed successfully only if they fed on a diet primarily of doves. Feeding on as little as 10% of other species such as starlings, robins, gulls and magpies would produce DDE concentrations in peregrine eggs greater than the threshold of 15 mg/kg. We also estimated the critical concentration of DDE in total prey to be about 0.5 mg/kg, one half of the previous most conservative criterion for peregrine prey. Concentrations of dieldrin and PCBs in peregrine prey are less than suggested critical levels.
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influence of food supply and Chlorinated Hydrocarbon contaminants on breeding success of bald eagles
Ecotoxicology, 2003Co-Authors: Christopher E Gill, John E ElliottAbstract:Food supply and contaminants were investigated as possible causes of low bald eagle productivity near a bleached kraft pulp and paper mill at Crofton on Vancouver Island, British Columbia. Over a seven year period, 1992–1998, average productivity of five eagle territories situated south of the pulp mill at Crofton was significantly lower (0.43 young/occupied territory) than six territories north of the mill (1.04 young/occupied territory). A reference population of 32 territories located in Barkley Sound on the west coast of Vancouver Island demonstrated intermediary mean productivity (0.75 young/occupied territory). Measures of prey biomass delivered to nests were lowest south of the mill, and correlated significantly with nesting success. On average, measures of energy delivered to nests and a parameter determined to be related to prey availability, adult nest attendance time, accounted for about 70% of variability in nest success. Contaminant concentrations, including pulp mill derived polyChlorinated dibenzo-p-dioxins (PCDDs) and polyChlorinated dibenzofurans (PCDFs), as well as dichlorodiphenyldichloroethane (DDE), polyChlorinated biphenyls (PCBs), and calculated tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) were significantly greater in plasma samples of nestlings from south of the mill compared to the other two sites, but did not correlate significantly with individual nest success data. Nests south of the mill concentrate around Maple Bay, which appears to be a deposition area for contaminants transported by tides and currents from sources such as the pulp mill. Concentrations of DDE and PCBs in plasma of nestling eagles from south of the mill were less than the critical values estimated to affect production of young. For TEQs, there are no published critical values for plasma by which to compare our results. We conclude that less than adequate energy provisioning to nests, presumably related to low prey availability, was likely the main cause of poor nest success south of the mill site at Crofton. However, higher concentrations of both DDE and PCDD/F derived TEQs may have acted in concert with food stress to further reduce bald eagle productivity.
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reproductive success and Chlorinated Hydrocarbon contamination in tree swallows tachycineta bicolor nesting along rivers receiving pulp and paper mill effluent discharges
Environmental Pollution, 2000Co-Authors: M L Harris, John E ElliottAbstract:The insectivorous tree swallow was chosen as an indicator species to investigate the uptake of pulp mill-related Chlorinated Hydrocarbons from emergent aquatic insects. Nest box populations were monitored for reproductive success at locations upstream and downstream of pulp mills on two river systems in British Columbia, Canada. Also, 16-day-old nestlings were collected and analysed for polyChlorinated biphenyls (PCBs), polyChlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), pesticides, chlorophenols and chloroguaiacols. Most reproductive parameters were not different between populations at upstream and downstream locations, and were equivalent to or greater than those recorded for other tree swallow populations. Chlorinated Hydrocarbon contamination of nestlings was low at all sites. The highest tissue concentrations were detected downstream of pulp mills on the Fraser River, where PCDD and PCDF patterns along with the presence of pentachlorophenol (PCP) suggested that the primary source of contaminants was past use of PCP for timber preservation. Although the absolute tissue concentration of contaminants was less, the toxic concentration (as estimated with I-TEQs) was greatest in nestlings downstream of a pulp mill on the Thompson River. The proportionately larger contributions from 2,3,7,8-TCDF and PCB-77 elevated these TEQs in comparison to other populations. Nest success was the one reproductive measure that showed substantial reductions in downstream populations on both rivers; however, there was little indication that nest failures were the direct result of contamination. Failures were largely due to parental abandonment, and, while poor parental attentiveness and nest abandonment have been associated with Chlorinated Hydrocarbon tissue concentrations in other studies, our 1-year assessment was insufficient to establish any link with pulp mill effluent exposure. Nestling growth models showed some subtle differences in growth patterns between nest box populations on the two rivers, but an association with pulp mill effects on aquatic insect prey availability was not established.
Ross J Norstrom - One of the best experts on this subject based on the ideXlab platform.
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composition of Chlorinated Hydrocarbon contaminants among major adipose tissue depots of polar bears ursus maritimus from the canadian high arctic
Science of The Total Environment, 2006Co-Authors: Jonathan Verreault, Ross J Norstrom, Malcolm A Ramsay, Michael Mulvihill, Robert J LetcherAbstract:Monitoring of environmental contaminants in Canadian Arctic polar bears (Ursus maritimus) typically has used superficial adipose tissue samples collected as part of controlled native subsistence hunts. However, little attention has been paid to the compositional difference in contaminants that may exist among the major adipose depots that are routinely collected. To address this knowledge gap, we investigated the profiles and concentrations of Chlorinated Hydrocarbon contaminants (CHCs), including major polyChlorinated biphenyl (PCB) congeners and organochlorine (OC) pesticides and metabolites, in six major adipose depots (i.e. superficial, inter-muscular and intra-abdominal regions) obtained from adult male polar bears in the vicinity of Resolute Bay, Canadian high Arctic. Concentrations and congener patterns of PCBs (20 congeners) and OCs (14 compounds; chlordanes and dichlorodiphenyltrichloroethanes and metabolites, Chlorinated benzenes, hexachlorocyclohexane isomers, octachlorostyrene and dieldrin) were found to be relatively uniform throughout the adipose tissue of male polar bears. The only exception was the inter-muscular adipose depot from the cervical region, which was characterized, compared to other major depots routinely sampled, by lower proportions of higher-Chlorinated and recalcitrant congeners such as CB170/190, 180, 194 and 206, and higher contribution of the lower-Chlorinated PCBs, CB47, 74 and 99. No difference in the OC makeup and concentrations was found among the adipose depots investigated. In view of this, we conclude that the determination of CHCs in adipose tissue of polar bears from any major depots, with the potential exception of the fat under the neck muscles, would give a representative picture of the overall CHC composition and concentrations in polar bear fat for purpose of trend monitoring.
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comprehensive re analysis of archived herring gull eggs reconstructs historical temporal trends in Chlorinated Hydrocarbon contamination in lake ontario and green bay lake michigan 1971 1982
Journal of Environmental Monitoring, 2006Co-Authors: Ross J Norstrom, Craig E HebertAbstract:Herring gull egg homogenates collected between 1971 and 1982 from a colony in central Lake Ontario (Scotch Bonnet Island) and from a colony in central Green Bay, Lake Michigan (Big Sister Island) were archived in the Canadian Wildlife Service Specimen Bank. Pooled samples (N = 10) were exhaustively analyzed in 1993 for a wide range of individual Chlorinated Hydrocarbon contaminant (CHC) compounds: DDT, mirex and chlordane compounds and metabolites, chlorobenzenes (CBzs), dieldrin, chlorostyrenes (CSs), hexachlorocyclohexanes (HCHs), polyChlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), and 87 PCB congeners, including the TCDD-like non-ortho and mono-ortho congeners. PCBs and DDTs were the dominant residues in eggs from both Lake Ontario (31–242 mg kg−1 and 9–64 mg kg−1) and Green Bay (34–133 mg kg−1 and 14–91 mg kg−1). ΣPCBs declined by a factor of 4–5 and DDTs a factor of 4–7 at both colonies between 1971 and 1982. Lake Ontario eggs had significantly higher residues of 2,3,7,8-TCDD (0.2–2.0 μg kg−1), HCBz (0.1–4.7 mg kg−1), OCS (0.03–0.45 mg kg−1), three HpCSs (0.13–0.97 mg kg−1), mirex and mirex photodegradation products (2.1–9.2 mg kg−1) than Green Bay eggs. HCBz levels in Lake Ontario eggs declined a factor of 40, TCDD and chlorostyrenes a factor of 8–10, and mirex a factor of 4 between 1971–1978. Green Bay eggs had slightly higher levels of chlordane-related compounds, dieldrin and β-HCH than Lake Ontario eggs. There were no consistent or strong trends in residue levels of these pesticides, PCDDs (except TCDD) and PCDFs in either lake, indicating that rates of input and removal of these CHCs in the lakes were much closer in the early 1970s than was the case for the other compounds.
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Chlorinated Hydrocarbon contaminants and metabolites in polar bears ursus maritimus from alaska canada east greenland and svalbard 1996 2002
Science of The Total Environment, 2005Co-Authors: Ross J Norstrom, Derek C G Muir, Jonathan Verreault, Ian Stirling, Aaron T Fisk, Geir W Gabrielsen, Andrew E Derocher, Thomas J Evans, Rune DietzAbstract:A suite of Chlorinated Hydrocarbon contaminants (CHCs) including organochlorine pesticides (OCPs) and by-products, polyChlorinated biphenyls (PCBs), and methyl sulfone (MeSO2) PCB and p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) metabolites were determined in adipose tissue of 107 adult and sub-adult polar bears, almost exclusively females, sampled between 1996 and 2002 from populations spanning Arctic and Subarctic regions of Alaska, Canada, East Greenland, and Svalbard. The East Greenland and Svalbard populations of polar bears were distinguished by higher proportions of dichlorodiphenyldichloroethane (DDT)-related compounds, nonachlors, oxychlordane, and higher-Chlorinated and persistent PCB congeners (hepta- to nona-Chlorinated). Conversely, Alaska, the westernmost population of the North American Arctic, was characterized by higher proportions of relatively volatile compounds such as hexachlorocyclohexanes (HCHs) and pentachlorobenzene (PnCBz), lower-Chlorinated PCB congeners (tri- to penta-Chlorinated), and lower proportions of oxychlordane. Geometric mean (GM) with 95% confidence limits (CL) ΣHCH concentrations were highest in Alaska male polar bear fat samples (GM 593; CL 363−909 ng g− 1 lipid weight), ΣDDT concentration were highest in East Greenland female samples (GM 309; CL 249−490 ng g− 1 l.w.), and Σ42PCB (GM 5972; CL 4637−9129 ng g− 1 l.w.) and ΣMeSO2-PCB (GM 198; CL 162−279 ng g− 1 l.w.) concentrations were highest in female samples collected from Svalbard. The distribution of Σ-chlordane-related compounds (ΣCHL), ΣCBz, mirex, and dieldrin was relatively uniform among the populations of polar bears investigated. The present 1996−2002 data of female polar bear fat samples was compared to spatial assessments of female polar bear fat samples collected between 1989 and 1993 from comparable populations. The two-point temporal comparisons showed a general decrease for age-adjusted mean concentrations of ΣCHL, p,p′-DDE, Σ42PCB, ΣMeSO2-PCB and 3-MeSO2-p,p′-DDE over a period of approximately 10 years. However, concentrations of dieldrin were comparatively unchanged. Comparisons of present 2001−2002 concentrations in fat of female polar bears from Western Hudson Bay showed great consistency with temporal trends (1991−1999) previously reported for the same region, i.e. the apparent non-decreasing trend of ΣCHL, β-HCH, ΣHCH and dieldrin, and the apparent declining trend for ΣPCB. However, present concentrations of α-HCH and ΣCBz were elevated, and ΣDDT was notably lower in Western Hudson Bay samples compared to the last measurements in fat samples collected in 1999, which was not in accord with reported temporal trends for this region. As a result of their relatively high degree of contamination, East Greenland and Svalbard polar bears are at higher health risk of contaminant exposure among Arctic and Subarctic populations. In addition to continued biomonitoring, further research on health and population status is needed to evaluate the impact from chronic exposure of polar bear populations to CHCs and their metabolites.
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Chlorinated Hydrocarbon contaminants and productivity of bald eagle populations on the pacific coast of canada
Environmental Toxicology and Chemistry, 1998Co-Authors: John E Elliott, Ross J NorstromAbstract:From 1991 to 1995, we studied bald eagle populations breeding near three pulp mills in the Strait of Georgia, in the Fraser River estuary, and at remote reference sites on the west coast of Vancouver Island, northern Johnstone Strait, and the Queen Charlotte Islands (Haida Gwaii). Our objective was to determine occupancy of breeding territories, measure nest success, and compare the results to Chlorinated Hydrocarbon levels in eggs and in nestling plasma samples. Blood samples were collected in 1993 and 1994 from 52 nestlings in 38 nests and plasma analyzed for polyChlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), organochlorine (OC), pesticides, and lipid content. Most measured compounds partitioned with plasma lipids, with the exception of hepta- and octaChlorinated dioxins and furans. Because of significant variation in plasma lipid content among sites, contaminant concentrations were adjusted using analysis of covariance (ANCOVA). Mean concentrations of 2,3,7,8-substituted PCDDs, PCDFs, and calculated international toxic equivalents (I-TEQs) in nestling plasma were highest in samples from near pulp mills on southeast Vancouver Island (Nanaimo and Crofton) and Powell River. Mean total PCB concentrations were also highest in the industrialized Strait of Georgia region, such as at Powell River (56 μg/kg), while OC pesticide concentrations, including 1,1-dichloroethylene bis(p-chlorophenyl) (DDE), did not vary significantly among sites. Nest success was followed for 5 years at 250 breeding territories in the nine study areas. Average productivity was higher at most study sites around the Strait of Georgia compared to the reference areas. There were no significant relationships between productivity and I-TEQs or any tetrachlorodibenzo-p-dioxin-like compounds for the whole data set; only DDE in plasma was weakly related to productivity. Likewise, there were no significant relationships between individual nest productivity and contaminant levels in eggs, based on previously published data. We also tested for variability within study areas by comparing productivity at nests adjacent to dioxin fishery closure areas at three pulp mills compared to nearby nests outside the closure areas. At two pulp mill sites, Powell River and Nanaimo, there were no differences in productivity; however, at Crofton, average productivity, 0.26 young/occupied territory, was significantly lower at nine bald eagle territories adjacent to a dioxin—fishery closure zone compared to eight territories outside of the closure area, 1.0 young/occupied territory. The cause of the low reproductive rate at Crofton has not been determined, although a toxicological explanation has not been ruled out.
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immunoquantitation and microsomal monooxygenase activities of hepatic cytochromes p4501a and p4502b and Chlorinated Hydrocarbon contaminant levels in polar bear ursus maritimus
Toxicology and Applied Pharmacology, 1996Co-Authors: Robert J Letcher, Ross J Norstrom, Malcolm A Ramsay, Stelvio M BandieraAbstract:Contamination of the Arctic ecosystem by anthropogenic compounds has resulted in exposure of polar bear (Ursus maritimus) to lipophilic Chlorinated Hydrocarbon contaminants (CHCs) accumulated through the marine food web. Liver samples were collected from 16 adult male polar bears in the Canadian arctic and subjected to chemical analysis for CHCs and metabolites, determination of alkoxyresorufinO-dealkylase activities, and immunoquantitation of cytochrome P450 (CYP) protein levels. We report on the relationships between the hepatic microsomal levels of immunoreactive CYP1A and CYP2B isozymes, catalytic activities, and hepatic CHC and metabolite concentrations in polar bear. We specifically explored the influence of several CHCs on the induction of hepatic CYP in polar bear and the potential use of immunoassay quantitation as a bioindicator of CHC exposure. PolyChlorinated biphenyls (PCBs) classed as CYP1A and mixed CYP1A/CYP2B inducers accounted for about 25% of the total PCB residues present (18,680 ± 5053 ng/g lipid). CYP1A protein content correlated strongly with hepatic levels of PCBs, PCDDs (0.032 ± 0.018 ng/g lipid), and PCDFs (0.011 ± 0.007 ng/g lipid) and their corresponding toxic equivalents (TEQ, 0.377 ± 0.182 ng/g lipid). Mono-ortho-CB-156, CB-157, and CB-105 were the predominant TEQ contributors. Correlations between CYP2B protein content and CHC residue levels in polar bear liver suggested thatortho-chlorine-substituted PCBs and chlordanes were the major contributors to CYP2B induction. CYP1A and CYP2B contents were therefore good indicators of CHC exposure in polar bear liver. Ethoxyresorufin, pentoxyresorufin, and benzyloxyresorufinO-dealkylase activities increased with increasing CYP1A protein content up to protein levels of approximately 5 pmol/mg, suggesting that all three activities were primarily CYP1A-mediated. These results were substantiated by antibody inhibition experiments. In summary, immunoquantitated CYP1A and CYP2B isozymes are a more reliable measure of exposure to CHC inducers than alkoxyresorufinO-dealkylase activities in polar bear.
Robert J Letcher - One of the best experts on this subject based on the ideXlab platform.
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composition of Chlorinated Hydrocarbon contaminants among major adipose tissue depots of polar bears ursus maritimus from the canadian high arctic
Science of The Total Environment, 2006Co-Authors: Jonathan Verreault, Ross J Norstrom, Malcolm A Ramsay, Michael Mulvihill, Robert J LetcherAbstract:Monitoring of environmental contaminants in Canadian Arctic polar bears (Ursus maritimus) typically has used superficial adipose tissue samples collected as part of controlled native subsistence hunts. However, little attention has been paid to the compositional difference in contaminants that may exist among the major adipose depots that are routinely collected. To address this knowledge gap, we investigated the profiles and concentrations of Chlorinated Hydrocarbon contaminants (CHCs), including major polyChlorinated biphenyl (PCB) congeners and organochlorine (OC) pesticides and metabolites, in six major adipose depots (i.e. superficial, inter-muscular and intra-abdominal regions) obtained from adult male polar bears in the vicinity of Resolute Bay, Canadian high Arctic. Concentrations and congener patterns of PCBs (20 congeners) and OCs (14 compounds; chlordanes and dichlorodiphenyltrichloroethanes and metabolites, Chlorinated benzenes, hexachlorocyclohexane isomers, octachlorostyrene and dieldrin) were found to be relatively uniform throughout the adipose tissue of male polar bears. The only exception was the inter-muscular adipose depot from the cervical region, which was characterized, compared to other major depots routinely sampled, by lower proportions of higher-Chlorinated and recalcitrant congeners such as CB170/190, 180, 194 and 206, and higher contribution of the lower-Chlorinated PCBs, CB47, 74 and 99. No difference in the OC makeup and concentrations was found among the adipose depots investigated. In view of this, we conclude that the determination of CHCs in adipose tissue of polar bears from any major depots, with the potential exception of the fat under the neck muscles, would give a representative picture of the overall CHC composition and concentrations in polar bear fat for purpose of trend monitoring.
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immunoquantitation and microsomal monooxygenase activities of hepatic cytochromes p4501a and p4502b and Chlorinated Hydrocarbon contaminant levels in polar bear ursus maritimus
Toxicology and Applied Pharmacology, 1996Co-Authors: Robert J Letcher, Ross J Norstrom, Malcolm A Ramsay, Stelvio M BandieraAbstract:Contamination of the Arctic ecosystem by anthropogenic compounds has resulted in exposure of polar bear (Ursus maritimus) to lipophilic Chlorinated Hydrocarbon contaminants (CHCs) accumulated through the marine food web. Liver samples were collected from 16 adult male polar bears in the Canadian arctic and subjected to chemical analysis for CHCs and metabolites, determination of alkoxyresorufinO-dealkylase activities, and immunoquantitation of cytochrome P450 (CYP) protein levels. We report on the relationships between the hepatic microsomal levels of immunoreactive CYP1A and CYP2B isozymes, catalytic activities, and hepatic CHC and metabolite concentrations in polar bear. We specifically explored the influence of several CHCs on the induction of hepatic CYP in polar bear and the potential use of immunoassay quantitation as a bioindicator of CHC exposure. PolyChlorinated biphenyls (PCBs) classed as CYP1A and mixed CYP1A/CYP2B inducers accounted for about 25% of the total PCB residues present (18,680 ± 5053 ng/g lipid). CYP1A protein content correlated strongly with hepatic levels of PCBs, PCDDs (0.032 ± 0.018 ng/g lipid), and PCDFs (0.011 ± 0.007 ng/g lipid) and their corresponding toxic equivalents (TEQ, 0.377 ± 0.182 ng/g lipid). Mono-ortho-CB-156, CB-157, and CB-105 were the predominant TEQ contributors. Correlations between CYP2B protein content and CHC residue levels in polar bear liver suggested thatortho-chlorine-substituted PCBs and chlordanes were the major contributors to CYP2B induction. CYP1A and CYP2B contents were therefore good indicators of CHC exposure in polar bear liver. Ethoxyresorufin, pentoxyresorufin, and benzyloxyresorufinO-dealkylase activities increased with increasing CYP1A protein content up to protein levels of approximately 5 pmol/mg, suggesting that all three activities were primarily CYP1A-mediated. These results were substantiated by antibody inhibition experiments. In summary, immunoquantitated CYP1A and CYP2B isozymes are a more reliable measure of exposure to CHC inducers than alkoxyresorufinO-dealkylase activities in polar bear.
Jonathan Verreault - One of the best experts on this subject based on the ideXlab platform.
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composition of Chlorinated Hydrocarbon contaminants among major adipose tissue depots of polar bears ursus maritimus from the canadian high arctic
Science of The Total Environment, 2006Co-Authors: Jonathan Verreault, Ross J Norstrom, Malcolm A Ramsay, Michael Mulvihill, Robert J LetcherAbstract:Monitoring of environmental contaminants in Canadian Arctic polar bears (Ursus maritimus) typically has used superficial adipose tissue samples collected as part of controlled native subsistence hunts. However, little attention has been paid to the compositional difference in contaminants that may exist among the major adipose depots that are routinely collected. To address this knowledge gap, we investigated the profiles and concentrations of Chlorinated Hydrocarbon contaminants (CHCs), including major polyChlorinated biphenyl (PCB) congeners and organochlorine (OC) pesticides and metabolites, in six major adipose depots (i.e. superficial, inter-muscular and intra-abdominal regions) obtained from adult male polar bears in the vicinity of Resolute Bay, Canadian high Arctic. Concentrations and congener patterns of PCBs (20 congeners) and OCs (14 compounds; chlordanes and dichlorodiphenyltrichloroethanes and metabolites, Chlorinated benzenes, hexachlorocyclohexane isomers, octachlorostyrene and dieldrin) were found to be relatively uniform throughout the adipose tissue of male polar bears. The only exception was the inter-muscular adipose depot from the cervical region, which was characterized, compared to other major depots routinely sampled, by lower proportions of higher-Chlorinated and recalcitrant congeners such as CB170/190, 180, 194 and 206, and higher contribution of the lower-Chlorinated PCBs, CB47, 74 and 99. No difference in the OC makeup and concentrations was found among the adipose depots investigated. In view of this, we conclude that the determination of CHCs in adipose tissue of polar bears from any major depots, with the potential exception of the fat under the neck muscles, would give a representative picture of the overall CHC composition and concentrations in polar bear fat for purpose of trend monitoring.
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Chlorinated Hydrocarbon contaminants and metabolites in polar bears ursus maritimus from alaska canada east greenland and svalbard 1996 2002
Science of The Total Environment, 2005Co-Authors: Ross J Norstrom, Derek C G Muir, Jonathan Verreault, Ian Stirling, Aaron T Fisk, Geir W Gabrielsen, Andrew E Derocher, Thomas J Evans, Rune DietzAbstract:A suite of Chlorinated Hydrocarbon contaminants (CHCs) including organochlorine pesticides (OCPs) and by-products, polyChlorinated biphenyls (PCBs), and methyl sulfone (MeSO2) PCB and p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) metabolites were determined in adipose tissue of 107 adult and sub-adult polar bears, almost exclusively females, sampled between 1996 and 2002 from populations spanning Arctic and Subarctic regions of Alaska, Canada, East Greenland, and Svalbard. The East Greenland and Svalbard populations of polar bears were distinguished by higher proportions of dichlorodiphenyldichloroethane (DDT)-related compounds, nonachlors, oxychlordane, and higher-Chlorinated and persistent PCB congeners (hepta- to nona-Chlorinated). Conversely, Alaska, the westernmost population of the North American Arctic, was characterized by higher proportions of relatively volatile compounds such as hexachlorocyclohexanes (HCHs) and pentachlorobenzene (PnCBz), lower-Chlorinated PCB congeners (tri- to penta-Chlorinated), and lower proportions of oxychlordane. Geometric mean (GM) with 95% confidence limits (CL) ΣHCH concentrations were highest in Alaska male polar bear fat samples (GM 593; CL 363−909 ng g− 1 lipid weight), ΣDDT concentration were highest in East Greenland female samples (GM 309; CL 249−490 ng g− 1 l.w.), and Σ42PCB (GM 5972; CL 4637−9129 ng g− 1 l.w.) and ΣMeSO2-PCB (GM 198; CL 162−279 ng g− 1 l.w.) concentrations were highest in female samples collected from Svalbard. The distribution of Σ-chlordane-related compounds (ΣCHL), ΣCBz, mirex, and dieldrin was relatively uniform among the populations of polar bears investigated. The present 1996−2002 data of female polar bear fat samples was compared to spatial assessments of female polar bear fat samples collected between 1989 and 1993 from comparable populations. The two-point temporal comparisons showed a general decrease for age-adjusted mean concentrations of ΣCHL, p,p′-DDE, Σ42PCB, ΣMeSO2-PCB and 3-MeSO2-p,p′-DDE over a period of approximately 10 years. However, concentrations of dieldrin were comparatively unchanged. Comparisons of present 2001−2002 concentrations in fat of female polar bears from Western Hudson Bay showed great consistency with temporal trends (1991−1999) previously reported for the same region, i.e. the apparent non-decreasing trend of ΣCHL, β-HCH, ΣHCH and dieldrin, and the apparent declining trend for ΣPCB. However, present concentrations of α-HCH and ΣCBz were elevated, and ΣDDT was notably lower in Western Hudson Bay samples compared to the last measurements in fat samples collected in 1999, which was not in accord with reported temporal trends for this region. As a result of their relatively high degree of contamination, East Greenland and Svalbard polar bears are at higher health risk of contaminant exposure among Arctic and Subarctic populations. In addition to continued biomonitoring, further research on health and population status is needed to evaluate the impact from chronic exposure of polar bear populations to CHCs and their metabolites.
S E Kahn - One of the best experts on this subject based on the ideXlab platform.
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adipose tissue serum partitioning of Chlorinated Hydrocarbon pesticides in humans
Chemosphere, 1990Co-Authors: Larry L Needham, Virlyn W Burse, Susan L Head, Margaret P Korver, Patricia C Mcclure, John Andrews, Diane L Rowley, J Sung, S E KahnAbstract:Abstract As more measurements of Chlorinated Hydrocarbons pesticides are being performed in serum as opposed to adipose tissue, it is important to know how these compounds partition between these two compartments. We have determined concentration ratios for seven of these compounds in humans; these ratios were calculated on an adipose lipid weight vs. serum whole weight, lipid weight and albumin content.