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Dietz R, Letcher RJ, Aars J, Andersen M, Boltunov A, Born EW, Ciesielski TM, Das K, Dastnai S, Derocher AE, Desforges JP, Eulaers I, Ferguson S, Hallanger IG, Heide-Jørgensen MP, Heimbürger-Boavida LE, Hoekstra PF, Jenssen BM, Kohler SG, Larsen MM, Lindstrøm U, Lippold A, Morris A, Nabe-Nielsen J, Nielsen NH, Peacock E, Pinzone M, Rigét FF, Rosing-Asvid A, Routti H, Siebert U, Stenson G, Stern G, Strand J, Søndergaard J, Treu G, Víkingsson GA, Wang F, Welker JM, Wiig Ø, Wilson SJ, Sonne C. A risk assessment review of mercury exposure in Arctic marine and terrestrial mammals. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 829:154445. [PMID: 35304145 DOI: 10.1016/j.scitotenv.2022.154445] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/25/2022] [Accepted: 03/06/2022] [Indexed: 06/14/2023]
Abstract
There has been a considerable number of reports on Hg concentrations in Arctic mammals since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of the exposure to mercury (Hg) in Arctic biota in 2010 and 2018. Here, we provide an update on the state of the knowledge of health risk associated with Hg concentrations in Arctic marine and terrestrial mammal species. Using available population-specific data post-2000, our ultimate goal is to provide an updated evidence-based estimate of the risk for adverse health effects from Hg exposure in Arctic mammal species at the individual and population level. Tissue residues of Hg in 13 species across the Arctic were classified into five risk categories (from No risk to Severe risk) based on critical tissue concentrations derived from experimental studies on harp seals and mink. Exposure to Hg lead to low or no risk for health effects in most populations of marine and terrestrial mammals, however, subpopulations of polar bears, pilot whales, narwhals, beluga and hooded seals are highly exposed in geographic hotspots raising concern for Hg-induced toxicological effects. About 6% of a total of 3500 individuals, across different marine mammal species, age groups and regions, are at high or severe risk of health effects from Hg exposure. The corresponding figure for the 12 terrestrial species, regions and age groups was as low as 0.3% of a total of 731 individuals analyzed for their Hg loads. Temporal analyses indicated that the proportion of polar bears at low or moderate risk has increased in East/West Greenland and Western Hudson Bay, respectively. However, there remain numerous knowledge gaps to improve risk assessments of Hg exposure in Arctic mammalian species, including the establishment of improved concentration thresholds and upscaling to the assessment of population-level effects.
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Affiliation(s)
- Rune Dietz
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark.
| | - Robert J Letcher
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON K1A 0H3, Canada.
| | - Jon Aars
- Norwegian Polar Institute, Tromsø NO-9296, Norway
| | | | - Andrei Boltunov
- Marine Mammal Research and Expedition Centre, 36 Nahimovskiy pr., Moscow 117997, Russia
| | - Erik W Born
- Greenland Institute of Natural Resources, P.O. Box 570, DK-3900 Nuuk, Greenland
| | - Tomasz M Ciesielski
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Krishna Das
- Freshwater and Oceanic sciences Unit of reSearch (FOCUS), University of Liege, 4000 Liege, Belgium
| | - Sam Dastnai
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Jean-Pierre Desforges
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark; Department of Environmental Studies and Science, University of Winnipeg, Winnipeg, MB, Canada
| | - Igor Eulaers
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark; Norwegian Polar Institute, Tromsø NO-9296, Norway
| | - Steve Ferguson
- Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, MB R3T 2N6, Canada; Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | | | | | - Lars-Eric Heimbürger-Boavida
- Géosciences Environnement Toulouse, CNRS/IRD/Université Paul Sabatier Toulouse III, Toulouse, France; Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, Marseille, France
| | | | - Bjørn M Jenssen
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark; Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Stephen Gustav Kohler
- Department of Chemistry, Norwegian University of Science and Technology, Realfagbygget, E2-128, Gløshaugen, NO-7491 Trondheim, Norway
| | - Martin M Larsen
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark
| | - Ulf Lindstrøm
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway; Department of Arctic Technology, Institute of Marine Research, FRAM Centre, NO-9007 Tromsø, Norway
| | - Anna Lippold
- Norwegian Polar Institute, Tromsø NO-9296, Norway
| | - Adam Morris
- Northern Contaminants Program, Crown-Indigenous Relations and Northern Affairs Canada, 15 Eddy Street, 14th floor, Gatineau, Quebec K1A 0H4, Canada
| | - Jacob Nabe-Nielsen
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark
| | - Nynne H Nielsen
- Greenland Institute of Natural Resources, P.O. Box 570, DK-3900 Nuuk, Greenland
| | - Elizabeth Peacock
- USGS Alaska Science Center, 4210 University Dr., Anchorage, AK 99508-4626, USA
| | - Marianna Pinzone
- Department of Environmental Studies and Science, University of Winnipeg, Winnipeg, MB, Canada
| | - Frank F Rigét
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark
| | - Aqqalu Rosing-Asvid
- Greenland Institute of Natural Resources, P.O. Box 570, DK-3900 Nuuk, Greenland
| | - Heli Routti
- Norwegian Polar Institute, Tromsø NO-9296, Norway
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstr. 6, DE-25761 Büsum, Germany
| | - Garry Stenson
- Northwest Atlantic Fisheries Centre, Department DFO-MPO, 80 EastWhite Hills vie, St John's A1C 5X1, Newfoundland and Labrador, Canada
| | - Gary Stern
- Centre for Earth Observation Sciences (CEOS), Clayton H. Riddell Faculty of Environment, Earth and Resources, University of Manitoba, 586Wallace Bld, 125 Dysart Rd., Winnipeg, Manitoba R3T, 2N2, Canada
| | - Jakob Strand
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark
| | - Jens Søndergaard
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark
| | - Gabriele Treu
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany
| | - Gisli A Víkingsson
- Marine and Freshwater Research Institute, Skúlagata 4, 101 Reykjavík, Iceland
| | - Feiyue Wang
- Centre for Earth Observation Sciences (CEOS), Clayton H. Riddell Faculty of Environment, Earth and Resources, University of Manitoba, 586Wallace Bld, 125 Dysart Rd., Winnipeg, Manitoba R3T, 2N2, Canada
| | - Jeffrey M Welker
- University of Alaska Anchorage, Anchorage 99508, United States; University of Oulu, Oulu 90014, Finland; University of the Arctic, Rovaniemi 96460, Finland
| | - Øystein Wiig
- Natural History Museum, University of Oslo, P.O. Box 1172, Blindern, N-0318 Oslo, Norway
| | - Simon J Wilson
- Arctic Monitoring and Assessment Programme (AMAP) Secretariat, Box 6606 Stakkevollan, N-9296 Tromsø, Norway
| | - Christian Sonne
- Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000 Roskilde, Denmark
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2
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Rogstad TW, Sonne C, Villanger GD, Ahlstøm Ø, Fuglei E, Muir DCG, Jørgensen E, Jenssen BM. Concentrations of vitamin A, E, thyroid and testosterone hormones in blood plasma and tissues from emaciated adult male Arctic foxes (Vulpes lagopus) dietary exposed to persistent organic pollutants (POPs). ENVIRONMENTAL RESEARCH 2017; 154:284-290. [PMID: 28119248 DOI: 10.1016/j.envres.2017.01.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 01/12/2017] [Accepted: 01/13/2017] [Indexed: 06/06/2023]
Abstract
The aim of the present study was to investigate the relationships and effects of oral POP exposure on retinol (vitamin A), α-tocopherol (vitamin E), thyroid hormones and testosterone in emaciated adult farmed Arctic foxes. Eight brother-pairs were exposed to either a diet containing naturally POP-contaminated minke whale blubber (Balaenoptera acutorostrata) (n=8), or a control diet containing pig (Sus scrofa) fat as the primary fat source (n=8) for 22 months. In the whale blubber containing feed the ∑POPs concentration was 802ng/g w.w. and it was 24ng/g w.w. in control feed. The liver mass was significantly higher and the ratio of FT4 (free thyroxine):FT3 (free triiodothyronine) was significantly lower in the POP exposed group as compared to the control group given feed with pig fat (both p<0.05). The exposed group revealed lower plasma and liver concentrations of α-tocopherol compared to the control group (both p<0.05). These results indicate that plasma FT4:FT3 ratio and plasma and liver α-tocopherol are valuable biomarker endpoints for chronic oral POP exposure in wild Arctic foxes. Based on this we suggest that plasma FT4:FT3 ratio and plasma and liver α-tocopherol are valuable biomarker endpoints for chronic POP exposure in wildlife Arctic foxes and that these perturbations may affect their health status.
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Affiliation(s)
- Tonje W Rogstad
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Christian Sonne
- Aarhus University, Faculty of Science and Technology, Department of Bioscience, Arctic Research Centre (ARC), Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark.
| | - Gro D Villanger
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway; Mental and Physical Health, Department of Child Health, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, 0473 Oslo, Norway
| | - Øystein Ahlstøm
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, N-1432 Ås, Norway
| | - Eva Fuglei
- Norwegian Polar Institute, FRAM Centre, NO-9296 Tromsø, Norway
| | - Derek C G Muir
- National Water Research Institute, Environment Canada, Burlington, Ontario, Canada L7R 4A6
| | - Even Jørgensen
- Department of Arctic and Marine Biology, UiT the Arctic University of Norway, N-9037 Tromsø, Norway
| | - Bjørn Munro Jenssen
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
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Kong D, Wang Y, Wang J, Teng Y, Li N, Li J. Evaluation and characterization of thyroid-disrupting activities in soil samples along the Second Songhua River, China. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2016; 133:475-480. [PMID: 27526021 DOI: 10.1016/j.ecoenv.2016.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 08/05/2016] [Accepted: 08/08/2016] [Indexed: 06/06/2023]
Abstract
In this study, a recombinant thyroid receptor (TR) gene yeast assay combined with Monte Carlo simulation were used to evaluate and characterize soil samples collected from Jilin (China) along the Second Songhua River, for their ant/agonist effect on TR. No TR agonistic activity was found in soils, but many soil samples exhibited TR antagonistic activities, and the bioassay-derived amiodarone hydrochloride equivalents, which was calculated based on Monte Carlo simulation, ranged from not detected (N.D.) to 35.5μg/g. Hydrophilic substance fractions were determined to be the contributors to TR antagonistic activity in these soil samples. Our results indicate that the novel calculation method is effective for the quantification and characterization of TR antagonists in soil samples, and these data could provide useful information for future management and remediation efforts for contaminated soils.
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Affiliation(s)
- Dongdong Kong
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China
| | - Yafei Wang
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China
| | - Jinsheng Wang
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China
| | - Yanguo Teng
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China
| | - Na Li
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China
| | - Jian Li
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China.
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Hoydal KS, Ciesielski TM, Borrell A, Wasik A, Letcher RJ, Dam M, Jenssen BM. Relationships between concentrations of selected organohalogen contaminants and thyroid hormones and vitamins A, E and D in Faroese pilot whales. ENVIRONMENTAL RESEARCH 2016; 148:386-400. [PMID: 27131793 DOI: 10.1016/j.envres.2016.04.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 04/02/2016] [Accepted: 04/08/2016] [Indexed: 06/05/2023]
Abstract
Pilot whales (Globicephala melas) from the Faroe Islands, North-East Atlantic, have high body concentrations of organohalogenated compounds (OHCs), such as polychlorinated biphenyls (PCBs), organochlorinated pesticides (OCPs) and brominated flame retardants (BFRs). The aim of the present study was to examine if and to what extent blood plasma and liver concentrations of several groups of these OHCs are related to concentrations of relevant nutritional and hormonal biomarkers in pilot whales. Thyroid hormones (THs: total and free thyroxine and total and free triiodothyronine) and vitamin A (retinol), D (25-hydroxyvitamin D3) and E (α-tocopherol) were analysed in plasma (n=27) and vitamin A (total vitamin A, retinol and retinyl palmitate) and E (α- and γ-tocopherol) were analysed in liver (n=37) of Faroe Island pilot whales. Correlative relationships between the biomarkers and OHC concentrations previously analysed in the same tissues in these individuals were studied. The TH concentrations in plasma were significantly higher in juveniles than in adults. Vitamin D concentrations in plasma and α- and γ-tocopherol in liver were higher in adults than in juveniles. Multivariate statistical modelling showed that the age and sex influenced the relationship between biomarkers and OHCs. Some significant positive relationships were found between OHCs and thyroid hormone concentrations in the youngest juveniles (p<0.05). In plasma of juvenile whales α-tocopherol was also positively correlated with all the OHCs (p<0.05). Only few significant correlations were found between single OHCs and retinol and vitamin D in plasma within the age groups. There were significant negative relationships between hepatic PBDE concentrations and retinol (BDE-47) and γ-tocopherol (BDE-49, -47, -100, -99, -153) in liver. The relationships between OHCs and THs or vitamins suggest that in pilot whales OHCs seem to have minor effects on TH and vitamin concentrations.
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Affiliation(s)
- Katrin S Hoydal
- Department of Biology, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Environment Agency, Traðagøta 38, FO-165 Argir, Faroe Islands.
| | - Tomasz M Ciesielski
- Department of Biology, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Asunción Borrell
- Department of Animal Biology and Biodiversity Research Institute (IRBio), University of Barcelona, Spain
| | - Andrzej Wasik
- Gdańsk University of Technology, Chemical Faculty, Department of Analytical Chemistry, G. Narutowicza 11/12 St., 80-233 Gdańsk, Poland
| | - Robert J Letcher
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, 1125 Colonel By Dr. (Raven Road), Ottawa K1A 0H3, Canada
| | - Maria Dam
- Environment Agency, Traðagøta 38, FO-165 Argir, Faroe Islands
| | - Bjørn M Jenssen
- Department of Biology, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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Harley JR, Bammler TK, Farin FM, Beyer RP, Kavanagh TJ, Dunlap KL, Knott KK, Ylitalo GM, O'Hara TM. Using Domestic and Free-Ranging Arctic Canid Models for Environmental Molecular Toxicology Research. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:1990-1999. [PMID: 26730740 PMCID: PMC5290708 DOI: 10.1021/acs.est.5b04396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The use of sentinel species for population and ecosystem health assessments has been advocated as part of a One Health perspective. The Arctic is experiencing rapid change, including climate and environmental shifts, as well as increased resource development, which will alter exposure of biota to environmental agents of disease. Arctic canid species have wide geographic ranges and feeding ecologies and are often exposed to high concentrations of both terrestrial and marine-based contaminants. The domestic dog (Canis lupus familiaris) has been used in biomedical research for a number of years and has been advocated as a sentinel for human health due to its proximity to humans and, in some instances, similar diet. Exploiting the potential of molecular tools for describing the toxicogenomics of Arctic canids is critical for their development as biomedical models as well as environmental sentinels. Here, we present three approaches analyzing toxicogenomics of Arctic contaminants in both domestic and free-ranging canids (Arctic fox, Vulpes lagopus). We describe a number of confounding variables that must be addressed when conducting toxicogenomics studies in canid and other mammalian models. The ability for canids to act as models for Arctic molecular toxicology research is unique and significant for advancing our understanding and expanding the tool box for assessing the changing landscape of environmental agents of disease in the Arctic.
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Affiliation(s)
- John R. Harley
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, 900 Yukon Drive Room 194, Fairbanks, Alaska 99775-6160, United States
| | - Theo K. Bammler
- Center for Ecogenetics and Environmental Health, Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE #100, Seattle, Washington 98105 United States
| | - Federico M. Farin
- Center for Ecogenetics and Environmental Health, Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE #100, Seattle, Washington 98105 United States
| | - Richard P. Beyer
- Center for Ecogenetics and Environmental Health, Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE #100, Seattle, Washington 98105 United States
| | - Terrance J. Kavanagh
- Center for Ecogenetics and Environmental Health, Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE #100, Seattle, Washington 98105 United States
| | - Kriya L. Dunlap
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, 900 Yukon Drive Room 194, Fairbanks, Alaska 99775-6160, United States
| | - Katrina K. Knott
- Memphis Zoo, 2000 Prentiss Place, Memphis, Tennessee 38112, United States
| | - Gina M. Ylitalo
- Environmental Fisheries and Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Boulevard E. Seattle, Washington 98112-2013, United States
| | - Todd M. O'Hara
- Department of Veterinary Medicine, University of Alaska, Fairbanks, 901 Koyukuk Dr, Fairbanks, Alaska 99775-7750, United States
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Atkinson S, Crocker D, Houser D, Mashburn K. Stress physiology in marine mammals: how well do they fit the terrestrial model? J Comp Physiol B 2015; 185:463-86. [PMID: 25913694 DOI: 10.1007/s00360-015-0901-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/23/2015] [Accepted: 04/09/2015] [Indexed: 12/28/2022]
Abstract
Stressors are commonly accepted as the causal factors, either internal or external, that evoke physiological responses to mediate the impact of the stressor. The majority of research on the physiological stress response, and costs incurred to an animal, has focused on terrestrial species. This review presents current knowledge on the physiology of the stress response in a lesser studied group of mammals, the marine mammals. Marine mammals are an artificial or pseudo grouping from a taxonomical perspective, as this group represents several distinct and diverse orders of mammals. However, they all are fully or semi-aquatic animals and have experienced selective pressures that have shaped their physiology in a manner that differs from terrestrial relatives. What these differences are and how they relate to the stress response is an efflorescent topic of study. The identification of the many facets of the stress response is critical to marine mammal management and conservation efforts. Anthropogenic stressors in marine ecosystems, including ocean noise, pollution, and fisheries interactions, are increasing and the dramatic responses of some marine mammals to these stressors have elevated concerns over the impact of human-related activities on a diverse group of animals that are difficult to monitor. This review covers the physiology of the stress response in marine mammals and places it in context of what is known from research on terrestrial mammals, particularly with respect to mediator activity that diverges from generalized terrestrial models. Challenges in conducting research on stress physiology in marine mammals are discussed and ways to overcome these challenges in the future are suggested.
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Affiliation(s)
- Shannon Atkinson
- School of Fisheries and Ocean Sciences, Juneau Center, University of Alaska Fairbanks, 17101 Pt. Lena Loop Road, Juneau, AK, 99801, USA,
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Gabrielsen KM, Krokstad JS, Villanger GD, Blair DAD, Obregon MJ, Sonne C, Dietz R, Letcher RJ, Jenssen BM. Thyroid hormones and deiodinase activity in plasma and tissues in relation to high levels of organohalogen contaminants in East Greenland polar bears (Ursus maritimus). ENVIRONMENTAL RESEARCH 2015; 136:413-23. [PMID: 25460663 DOI: 10.1016/j.envres.2014.09.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 09/22/2014] [Accepted: 09/24/2014] [Indexed: 05/03/2023]
Abstract
Previous studies have shown relationships between organohalogen contaminants (OHCs) and circulating levels of thyroid hormones (THs) in arctic wildlife. However, there is a lack of knowledge concerning the possible functional effects of OHCs on TH status in target tissues for TH-dependent activity. The relationships between circulating (plasma) levels of OHCs and various TH variables in plasma as well as in liver, muscle and kidney tissues from East Greenland sub-adult polar bears (Ursus maritimus) sampled in 2011 (n=7) were therefore investigated. The TH variables included 3.3',5.5'-tetraiodothyronine or thyroxine (T4), 3.3',5-triiodothyronine (T3) and type 1 (D1) and type 2 (D2) deiodinase activities. Principal component analysis (PCA) combined with correlation analyses demonstrated negative relationships between individual polychlorinated biphenyls (PCBs) and their hydroxylated (OH-) metabolites and T4 in both plasma and muscle. There were both positive and negative relationships between individual OHCs and D1 and D2 activities in muscle, liver and kidney tissues. In general, PCBs, OH-PCBs and polybrominated dipehenyl ethers (PBDEs) were positively correlated to D1 and D2 activities, whereas organochlorine pesticides and byproducts (OCPs) were negatively associated with D1 and D2 activities. These results support the hypothesis that OHCs can affect TH status and action in the target tissues of polar bears. TH levels and deiodinase activities in target tissues can be sensitive endpoints for exposure of TH-disrupting compounds in arctic wildlife, and thus, tissue-specific responses in target organs should be further considered when assessing TH disruption in wildlife studies.
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Affiliation(s)
| | - Julie Stene Krokstad
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Gro Dehli Villanger
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway; Division of Mental Health, Department of Child Development and Mental Health, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, 0473 Oslo, Norway
| | - David A D Blair
- Ecotoxicology and Wildlife Health Division, Science and Technology Branch, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, Canada K1A 0H3; Department of Chemistry, Carleton University, Ottawa, Ontario, Canada K1S 5B6
| | - Maria-Jesus Obregon
- Instituto de Investigaciones Biomedicas, Centro Mixto from CSIC-UAM, 28029 Madrid, Spain
| | - Christian Sonne
- Department of Bioscience, Arctic Research Centre, Aarhus University, Roskilde, P.O. Box 358, DK-4000, Denmark
| | - Rune Dietz
- Department of Bioscience, Arctic Research Centre, Aarhus University, Roskilde, P.O. Box 358, DK-4000, Denmark
| | - Robert J Letcher
- Ecotoxicology and Wildlife Health Division, Science and Technology Branch, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, Canada K1A 0H3; Department of Chemistry, Carleton University, Ottawa, Ontario, Canada K1S 5B6
| | - Bjørn Munro Jenssen
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
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Daso AP, Okonkwo JO, Jansen R, Forbes PBC, Kotzé A, Rohwer ER. Polybrominated diphenyl ethers (PBDEs) in eggshells of the Southern Ground-Hornbill (Bucorvus leadbeateri) and Wattled Crane (Bugeranus carunculatus) in South Africa. CHEMOSPHERE 2015; 118:284-292. [PMID: 25463252 DOI: 10.1016/j.chemosphere.2014.09.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 07/27/2014] [Accepted: 09/11/2014] [Indexed: 06/04/2023]
Abstract
This study was undertaken to assess the levels of eight PBDE congeners, namely: PBDE-17, 47, 100, 99, 154, 153, 183 and 209 in eggshells of Southern Ground-Hornbill (SGH) Bucorvus leadbeateri and Wattled Crane (WC) Bugeranus carunculatus obtained from different nesting sites within the eastern savanna of Limpopo Province and the midlands of KwaZulu-Natal, respectively. Analyses were performed using gas chromatography–mass spectrometry employing the electron impact ionization technique. The results obtained indicated that the lower brominated congeners were predominant in both species. The total PBDEs ranged between not detected (ND) to 264 μg g−1 lipid weight and 5.98–7146 μg g−1 lipid weight in the SGH and WC samples, respectively. More so, the mean recoveries of the 13C-labelled surrogate standards ranged between 40% (PBDE-100) and 136% (PBDE-99). The potential hazards to these birds via PBDEs exposure were evaluated by determining the hazard quotients (HQs) by employing the established Lowest Observed Effect Level (LOEL) values associated with impaired pipping and hatching success as well as that associated with impaired reproduction. HQs values varying from 0.58 to 0.94 and 27.71 to 45.27, respectively were obtained for SGH and WC species. This implies that the SGH populations are exposed to low to moderate hazards, while the WC populations are susceptible to high hazards. Considering the potential threats posed by PBDEs, particularly to the WC species, it is likely that exposure to the current environmental levels of PBDEs by these birds may contribute to their reduced breeding success and declining population trends.
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Braun JP, Bourgès-Abella N, Geffré A, Concordet D, Trumel C. The preanalytic phase in veterinary clinical pathology. Vet Clin Pathol 2014; 44:8-25. [PMID: 25438659 DOI: 10.1111/vcp.12206] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This article presents the general causes of preanalytic variability with a few examples showing specialists and practitioners that special and improved care should be given to this too often neglected phase. The preanalytic phase of clinical pathology includes all the steps from specimen collection to analysis. It is the phase where most laboratory errors occur in human, and probably also in veterinary clinical pathology. Numerous causes may affect the validity of the results, including technical factors, such as the choice of anticoagulant, the blood vessel sampled, and the duration and conditions of specimen handling. While the latter factors can be defined, influence of biologic and physiologic factors such as feeding and fasting, stress, and biologic and endocrine rhythms can often not be controlled. Nevertheless, as many factors as possible should at least be documented. The importance of the preanalytic phase is often not given the necessary attention, although the validity of the results and consequent clinical decision making and medical management of animal patients would likely be improved if the quality of specimens submitted to the laboratory was optimized.
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Affiliation(s)
- Jean-Pierre Braun
- Sciences cliniques, Université de Toulouse, UPS, INP, ENVT, UMS 0006, Toulouse, France
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10
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Abstract
Polychlorinated biphenyls (PCBs) are persistent environmental pollutants that can severely disrupt the endocrine system. In the present study, early-weaned male rats were administered a single dose of 2,3,6-2',5'-pentachlorinated biphenyl (PCB 95; 32 mg/kg per day, by i.p. injection) for two consecutive days (postnatal days (PNDs) 15 and 16) and killed 24 and 48 h after the administration of the last dose. Compared with the control group, administration of PCB 95 induced a reduction (P<0.01) in serum concentrations of thyroxine, triiodothyronine, and GH and an increase (P<0.01) in the serum concentration of TSH at PNDs 17 and 18. These conspicuous perturbations led to some histopathological deterioration in the thyroid gland characterized by follicular degeneration, edema, fibrosis, hemorrhage, luminal obliteration, and hypertrophy with reduced colloidal contents at PND 18. The dyshormonogenesis and thyroid dysgenesis may be attributed to the elevation of DNA fragmentation at PNDs 17 and 18. Furthermore, this hypothyroid state revealed higher (P<0.01) serum concentrations of leptin, adiponectin, and tumor necrosis factor and lower (P<0.01) serum concentrations of IGF1 and insulin at both PNDs compared with the control group. Interestingly, the body weight of the neonates in the PCB 95 group exhibited severe decreases throughout the experimental period in relation to that of the control group. These results imply that PCB 95 may act as a disruptor of the developmental hypothalamic-pituitary-thyroid axis. Hypothyroidism caused by PCB 95 may impair the adipokine axis, fat metabolism, and in general postnatal development. Thus, further studies need to be carried out to understand this concept.
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Affiliation(s)
- R G Ahmed
- Division of Anatomy and Embryology, Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, PO 62514, Egypt
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11
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Goldner WS, Sandler DP, Yu F, Shostrom V, Hoppin JA, Kamel F, LeVan TD. Hypothyroidism and pesticide use among male private pesticide applicators in the agricultural health study. J Occup Environ Med 2013; 55:1171-8. [PMID: 24064777 PMCID: PMC3795845 DOI: 10.1097/jom.0b013e31829b290b] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Evaluate the association between thyroid disease and use of insecticides, herbicides, and fumigants/fungicides in male applicators in the Agricultural Health Study. METHODS We examined the association between use of 50 specific pesticides and self-reported hypothyroidism, hyperthyroidism, and "other" thyroid disease among 22,246 male pesticide applicators. RESULTS There was increased odds of hypothyroidism with ever use of the herbicides 2,4-D (2,4-dichlorophenoxyacetic acid), 2,4,5-T (2,4,5-trichlorophenoxyacetic acid), 2,4,5-TP (2,4,5-trichlorophenoxy-propionic acid), alachlor, dicamba, and petroleum oil. Hypothyroidism was also associated with ever use of eight insecticides: organochlorines chlordane, dichlorodiphenyltrichloroethane (DDT), heptachlor, lindane, and toxaphene; organophosphates diazinon and malathion; and the carbamate carbofuran. Exposure-response analysis showed increasing odds with increasing level of exposure for the herbicides alachlor and 2,4-D and the insecticides aldrin, chlordane, DDT, lindane, and parathion. CONCLUSION There is an association between hypothyroidism and specific herbicides and insecticides in male applicators, similar to previous results for spouses.
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Affiliation(s)
- Whitney S. Goldner
- Diabetes, Endocrinology and Metabolism Division, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198
| | - Dale P. Sandler
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
| | - Fang Yu
- Department of Biostatistics, College of Public Health, University of Nebraska Medical Center, Omaha, NE, 68198
| | - Valerie Shostrom
- Department of Biostatistics, College of Public Health, University of Nebraska Medical Center, Omaha, NE, 68198
| | - Jane A. Hoppin
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
| | - Freya Kamel
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
| | - Tricia D. LeVan
- Pulmonary, Critical Care, Sleep, and Allergy Division, Department of Internal Medicine and Department of Epidemiology, University of Nebraska Medical Center, Omaha, NE, 68198
- VA Nebraska-Western Iowa Health Care System Research Service, Department of Veterans Affairs Medical Center, 4101 Woolworth Avenue, Omaha, NE 68105
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12
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Villanger GD, Gabrielsen KM, Kovacs KM, Lydersen C, Lie E, Karimi M, Sørmo EG, Jenssen BM. Effects of complex organohalogen contaminant mixtures on thyroid homeostasis in hooded seal (Cystophora cristata) mother-pup pairs. CHEMOSPHERE 2013; 92:828-842. [PMID: 23726007 DOI: 10.1016/j.chemosphere.2013.04.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 04/07/2013] [Accepted: 04/08/2013] [Indexed: 06/02/2023]
Abstract
Many lipid-soluble and phenolic compounds present in the complex mixture of orgaohalogen contaminants (OHCs) that arctic wildlife is exposed to have the ability to interfere with the thyroid hormone (TH) system. The aim of this study was to identify compounds that might interfere with thyroid homeostasis in 14 nursing hooded seal (Cystophora cristata) mothers and their pups (1-4d old) sampled in the West Ice in March 2008. Multivariate modelling was used to assess the potential effects of measured plasma levels of OHCs on circulating TH levels of the measured free (F) and total (T) levels of triidothyrine (T3) and thyroxine (T4). Biological factors were important in all models (e.g. age and sex). In both mothers and pups, TT3:FT3 ratios were associated with α- and β-hexachlorocyclohexane (HCH), ortho-PCBs, chlordanes and DDTs. The similarities between the modelled TT3:FT3 responses to OHC levels in hooded seal mothers and pups most probably reflects similar exposure patterns, but could also indicate interconnected TH responses. There were some differences in the modelled TH responses of mothers and pups. Most importantly, the negative relationships between many OH-PCBs (particularly 3'-OH-CB138) and TT3:FT3 ratio and the positive relationships between TT4:FT4 ratios and polybrominated diphenyl ether [PBDE]-99, -100 and 4-OH-CB107 in pups, which was not found in mothers. Although statistical associations are not evidence per se of biological cause-effect relationships, the results suggest that thyroid homeostasis is affected in hooded seals, and that the inclusion of the fullest possible OHC mixture is important when assessing TH related effects in wildlife.
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Affiliation(s)
- Gro D Villanger
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
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13
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Bellingham M, Fiandanese N, Byers A, Cotinot C, Evans NP, Pocar P, Amezaga MR, Lea RG, Sinclair KD, Rhind SM, Fowler PA. Effects of Exposure to Environmental Chemicals During Pregnancy on the Development of the Male and Female Reproductive Axes. Reprod Domest Anim 2012; 47 Suppl 4:15-22. [DOI: 10.1111/j.1439-0531.2012.02050.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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14
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Boas M, Feldt-Rasmussen U, Main KM. Thyroid effects of endocrine disrupting chemicals. Mol Cell Endocrinol 2012; 355:240-8. [PMID: 21939731 DOI: 10.1016/j.mce.2011.09.005] [Citation(s) in RCA: 421] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 05/29/2011] [Accepted: 09/02/2011] [Indexed: 11/17/2022]
Abstract
In recent years, many studies of thyroid-disrupting effects of environmental chemicals have been published. Of special concern is the exposure of pregnant women and infants, as thyroid disruption of the developing organism may have deleterious effects on neurological outcome. Chemicals may exert thyroid effects through a variety of mechanisms of action, and some animal experiments and in vitro studies have focused on elucidating the mode of action of specific chemical compounds. Long-term human studies on effects of environmental chemicals on thyroid related outcomes such as growth and development are still lacking. The human exposure scenario with life long exposure to a vast mixture of chemicals in low doses and the large physiological variation in thyroid hormone levels between individuals render human studies very difficult. However, there is now reasonably firm evidence that PCBs have thyroid-disrupting effects, and there is emerging evidence that also phthalates, bisphenol A, brominated flame retardants and perfluorinated chemicals may have thyroid disrupting properties.
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Affiliation(s)
- Malene Boas
- Department of Growth and Reproduction GR, Rigshospitalet, University of Copenhagen, Denmark.
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15
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Hallanger IG, Jørgensen EH, Fuglei E, Ahlstrøm Ø, Muir DCG, Jenssen BM. Dietary contaminant exposure affects plasma testosterone, but not thyroid hormones, vitamin A, and vitamin E, in male juvenile arctic foxes (Vulpes lagopus). JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2012; 75:1298-1313. [PMID: 23030655 DOI: 10.1080/15287394.2012.709445] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Levels of persistent organic pollutants (POP), such as polychlorinated biphenyls (PCB), are high in many Arctic top predators, including the Arctic fox (Vulpes lagopus). The aim of this study was to examine possible endocrine-disruptive effects of dietary POP exposure in male juvenile Arctic foxes in a controlled exposure experiment. The study was conducted using domesticated farmed blue foxes (Vulpes lagopus) as a model species. Two groups of newly weaned male foxes received a diet supplemented with either minke whale (Baleneoptera acutorostrata) blubber that was naturally contaminated with POP (exposed group, n = 5 or 21), or pork (Sus scrofa) fat (control group, n = 5 or 21). When the foxes were 6 mo old and had received the 2 diets for approximately 4 mo (147 d), effects of the dietary exposure to POP on plasma concentrations of testosterone (T), thyroid hormones (TH), thyroid-stimulating hormone (TSH), retinol (vitamin A), and tocopherol (viramin E) were examined. At sampling, the total body concentrations of 104 PCB congeners were 0.1 ± 0.03 μg/g lipid weight (l.w.; n = 5 [mean ± standard deviation]) and 1.5 ± 0.17 μg/g l.w. (n = 5) in the control and exposed groups, respectively. Plasma testosterone concentrations in the exposed male foxes were significantly lower than in the control males, being approximately 25% of that in the exposed foxes. There were no between-treatment differences for TH, TSH, retinol, or tocopherol. The results suggest that the high POP levels experienced by costal populations of Arctic foxes, such as in Svalbard and Iceland, may result in delayed masculine maturation during adolescence. Sex hormone disruption during puberty may thus have lifetime consequences on all aspects of reproductive function in adult male foxes.
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Julvez J, Debes F, Weihe P, Choi AL, Grandjean P. Thyroid dysfunction as a mediator of organochlorine neurotoxicity in preschool children. ENVIRONMENTAL HEALTH PERSPECTIVES 2011; 119:1429-35. [PMID: 21719373 PMCID: PMC3230434 DOI: 10.1289/ehp.1003172] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 06/30/2011] [Indexed: 05/23/2023]
Abstract
BACKGROUND Exposure to organochlorine compounds (OCs) can alter thyroid function in humans, and hypothyroidism during early life can adversely affect a child's neurodevelopment. OBJECTIVES In this study we aimed to assess the relationship between developmental organochlorine exposures and thyroid function and the relationship between thyroid function and subsequent neurodevelopment. METHODS A population-based birth cohort of 182 children was followed annually up to 5.5 years of age. The assessments included OC concentrations in maternal pregnancy serum and milk, clinical thyroid parameters in maternal and cord serum, and subsequent neuropsychological outcomes of the child, along with sociodemographic cofactors. Resin triiodothyronine uptake ratio (T3RU) was also assessed as an estimate of the amount of thyroxine-binding globulin (TBG) sites unsaturated by thyroxine. The T3RU is high in hyperthyroidism and low in hypothyroidism. RESULTS The findings showed consistent inverse and monotonic associations between organochlorine exposure and T3RU after covariate adjustments. We observed no associations with other thyroid parameters. T3RU was positively associated with improved performance on most of the neuropsychological tests. For other thyroid parameters, the findings were less consistent. CONCLUSIONS The results suggest that OC exposures may decrease the T3RU during early life, which is a proxy measure of the binding capacity of TBG. In addition, minor decreases of the thyroid function may be inversely associated with a child's neurodevelopment.
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Affiliation(s)
- Jordi Julvez
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA.
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17
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Villanger GD, Lydersen C, Kovacs KM, Lie E, Skaare JU, Jenssen BM. Disruptive effects of persistent organohalogen contaminants on thyroid function in white whales (Delphinapterus leucas) from Svalbard. THE SCIENCE OF THE TOTAL ENVIRONMENT 2011; 409:2511-2524. [PMID: 21497377 DOI: 10.1016/j.scitotenv.2011.03.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 03/13/2011] [Accepted: 03/15/2011] [Indexed: 05/30/2023]
Abstract
We analysed levels of 56 organohalogen contaminants (OHCs) including brominated flame retardants, polychlorinated biphenyls (PCBs), and organochlorine pesticides in the blubber of white (beluga) whales (Delphinapterus leucas) from Svalbard, Norway (N=12; 6 adults [5 males and 1 female] and 6 subadults [4 males and 2 females]) collected in 1996-2001. We also measured circulating levels of thyroid hormones (THs) and thyroid stimulating hormone (TSH) in the whales. The results confirm that OHC levels in these white whales are among the highest levels recorded in wildlife from Svalbard, and at the high end of the range when compared to white whales from the North American Arctic. A projection to latent structure (PLS) model (subadults and adult males grouped together) revealed that known or suspected thyroid disruptive contaminants (polybrominated diphenylether [PBDE]-28, -47, -99, -100, and -154, hexachlorobenzene [HCB], and PCB-105) were negatively correlated with circulating levels of total thyroxin (TT4), free T4 (FT4) and free triiodothyronine (FT3). Most of these negative relationships were also confirmed using partial correlations controlling for length (and thus age) of the whales. The positive correlations of TT4, FT4 and FT3 with hexabromocyclododecane (HBCD), α-hexachlorocyclohexane (α-HCH), chlorinated bornanes CHB-40 and CHB-62 revealed by the PLS model were not confirmed by partial correlations. TH levels in the present study appeared to be somewhat lower than levels measured in beluga whales from the Canadian Arctic. However, we were not able to determine if this was caused by different levels of OHCs, or differences in biological factors (e.g. age, sex, moulting status, and season) and analytical methods between the studies. Although the sample sizes were low and statistical models cannot depict the biological cause-effect relationships, this study suggests negative influences of specific OHCs, particularly PBDEs, on thyroid hormone levels in white whales. The impact this might have on individual and population health is unknown.
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Affiliation(s)
- G D Villanger
- Department of Biology, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway.
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18
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Villanger GD, Jenssen BM, Fjeldberg RR, Letcher RJ, Muir DCG, Kirkegaard M, Sonne C, Dietz R. Exposure to mixtures of organohalogen contaminants and associative interactions with thyroid hormones in East Greenland polar bears (Ursus maritimus). ENVIRONMENT INTERNATIONAL 2011; 37:694-708. [PMID: 21345491 DOI: 10.1016/j.envint.2011.01.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 12/02/2010] [Accepted: 01/20/2011] [Indexed: 05/05/2023]
Abstract
We investigated the multivariate relationships between adipose tissue residue levels of 48 individual organohalogen contaminants (OHCs) and circulating thyroid hormone (TH) levels in polar bears (Ursus maritimus) from East Greenland (1999-2001, n=62), using projection to latent structure (PLS) regression for four groupings of polar bears; subadults (SubA), adult females with cubs (AdF_N), adult females without cubs (AdF_S) and adult males (AdM). In the resulting significant PLS models for SubA, AdF_N and AdF_S, some OHCs were especially important in explaining variations in circulating TH levels: polybrominated diphenylether (PBDE)-99, PBDE-100, PBDE-153, polychlorinated biphenyl (PCB)-52, PCB-118, cis-nonachlor, trans-nonachlor, trichlorobenzene (TCB) and pentachlorobenzene (QCB), and both negative and positive relationships with THs were found. In addition, the models revealed that DDTs had a positive influence on total 3,5,3'-triiodothyronine (TT3) in AdF_S, and that a group of 17 higher chlorinated ortho-PCBs had a positive influence on total 3,5,3',5'-tetraiodothyronine (thyroxine, TT4) in AdF_N. TH levels in AdM seemed less influenced by OHCs because of non-significant PLS models. TH levels were also influenced by biological factors such as age, sex, body size, lipid content of adipose tissue and sampling date. When controlling for biological variables, the major relationships from the PLS models for SubA, AdF_N and AdF_S were found significant in partial correlations. The most important OHCs that influenced TH levels in the significant PLS models may potentially act through similar mechanisms on the hypothalamic-pituitary-thyroid (HPT) axis, suggesting that both combined effects by dose and response addition and perhaps synergistic potentiation may be a possibility in these polar bears. Statistical associations are not evidence per se of biological cause-effect relationships. Still, the results of the present study indicate that OHCs may affect circulating TH levels in East Greenland polar bears, adding to the "weight of evidence" suggesting that OHCs might interfere with thyroid homeostasis in polar bears.
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Affiliation(s)
- Gro D Villanger
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway.
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